Post diploma,paper 2 1. resuscitation in pregnant women , surviving sepsis guidlines 2. ⁠lft and their significane, child pugh score 3. ⁠usg guided adductor canal block, renal replacement therapy 4. ⁠types of labour analgesia, pain pathway in labour pain 5. anaesthesia challenges and mgt of posterior fossa tumour 6. ⁠airway management of maxillofacial trauma plus manual inline stabilization 7. ⁠anaesthesia mgt of 2 year old paediatric who has foreign body insertion taken for emergency 8. ⁠biochemical changes of stored blood, indication and complication of blood transfusion 9. link 25, electrical safety of OT 10. ⁠post op analgesia for paediatric in lower abdominal surgery and thoracotomy Answer these question for dnb anaesthesia exam take from genuine source like miller morgon stoeiltinng etc

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general-purpose

You are a DNB Anaesthesia exam expert. Research the following 5 topics from the medical library database and provide comprehensive exam-ready answers. Use query_library_db to search, then read the relevant file sections. TOPICS TO RESEARCH: 1. **Resuscitation in pregnant women** - CPR modifications in pregnancy, left lateral tilt, perimortem caesarean section (within 5 minutes), ACLS in pregnancy, airway management, defibrillation in pregnancy 2. **Surviving Sepsis Guidelines** - Hour-1 bundle, fluid resuscitation (30ml/kg crystalloid), vasopressors (norepinephrine first line), antibiotics (within 1 hour), lactate measurement, source control, corticosteroids in refractory septic shock, ventilation targets 3. **Liver Function Tests and their significance** - ALT, AST, ALP, GGT, bilirubin (direct/indirect), albumin, PT/INR, total protein - normal values and clinical significance, pattern of liver disease (hepatocellular vs cholestatic) 4. **Child-Pugh score** - Parameters (bilirubin, albumin, PT, ascites, encephalopathy), scoring (1-3 for each), Class A/B/C, anaesthetic significance, surgical risk assessment 5. **Types of labour analgesia + Pain pathway in labour pain** - First stage pain (T10-L1, visceral), second stage pain (S2-S4, somatic), epidural analgesia technique, CSE, spinal, systemic opioids (entonox, remifentanil PCA), paracervical block, pudendal block. Include dermatomal levels. SEARCH INSTRUCTIONS: - Use headings_fts and paragraphs_fts to find relevant sections - Read the actual file content using read_file - Cite specific textbooks (Miller's Anaesthesia, Morgan & Mikhail, Stoelting, etc.) - Provide comprehensive exam-oriented answers with key points, tables where appropriate Return a detailed, structured answer for ALL 5 topics suitable for a DNB Post-Diploma Paper 2 exam.

general-purpose

You are a DNB Anaesthesia exam expert. Research the following 5 topics from the medical library database and provide comprehensive exam-ready answers. Use query_library_db to search, then read the relevant file sections. TOPICS TO RESEARCH: 1. **USG-guided adductor canal block** - Anatomy (subsartorial canal, saphenous nerve, VMCN, nerve to vastus medialis), probe position (mid-thigh), sonoanatomy, technique, volume/drug, indications (TKR), advantages over femoral nerve block (preserved quadriceps strength), complications 2. **Renal Replacement Therapy (RRT)** - Indications (AEIOU: acidosis, electrolytes, intoxication, overload, uremia), types (IHD, CRRT - CVVH/CVVHD/CVVHDF), anticoagulation (heparin, citrate), timing of initiation, KDIGO criteria, differences between modalities, dose recommendations 3. **Anaesthesia challenges and management of posterior fossa tumour** - Sitting vs prone positioning, venous air embolism (VAE) - detection (precordial doppler, TEE, ETCO2 drop), treatment of VAE, ICP management, brainstem monitoring, IONM, specific concerns (facial nerve, IX/X/XI/XII monitoring), emergence/extubation concerns, postoperative complications 4. **Airway management of maxillofacial trauma + Manual Inline Stabilisation (MILS)** - Assessment (airway obstruction risk, haemorrhage, trismus, C-spine precaution), RSI vs awake FOI, MILS technique (does not apply traction), worsening of laryngoscopy grade with MILS, alternatives (videolaryngoscopy, surgical airway), cricothyroidotomy, retrograde intubation, specific fractures (mandible, Le Fort I/II/III, panfacial) 5. **Biochemical changes of stored blood + Indications and complications of blood transfusion** - Storage lesion: pH decrease, K+ increase (up to 30 mEq/L), 2,3-DPG decrease (left shift oxyhb curve), decreased ATP, microaggregates, citrate toxicity. Indications: Hb trigger (7g/dL ICU, 8g/dL cardiac surgery), massive transfusion. Complications: TRALI, TACO, FNHTR, allergic reactions, transfusion-transmitted infections, hypocalcaemia, hypothermia, dilutional coagulopathy SEARCH INSTRUCTIONS: - Use headings_fts and paragraphs_fts to find relevant sections - Read the actual file content using read_file - Cite specific textbooks (Miller's Anaesthesia, Morgan & Mikhail, Stoelting, etc.) - Provide comprehensive exam-oriented answers with key points, tables where appropriate Return a detailed, structured answer for ALL 5 topics suitable for a DNB Post-Diploma Paper 2 exam.

general-purpose

You are a DNB Anaesthesia exam expert. Research the following 3 topics from the medical library database and provide comprehensive exam-ready answers. Use query_library_db to search, then read the relevant file sections. TOPICS TO RESEARCH: 1. **Anaesthesia management of 2-year-old with foreign body (emergency)** - Preoperative assessment (NPO status - full stomach in emergency, type of foreign body, location), induction technique (inhalational vs IV - debate), maintaining spontaneous ventilation vs controlled, rigid bronchoscopy technique (Venturi jet ventilation vs spontaneous), use of sevoflurane, dexmedetomidine, propofol TIVA, airway equipment (sizes for 2-year-old: ETT 4.5 uncuffed, LMA size 2, blade size 1), specific concerns (hypoxia, complete obstruction during manipulation), post-op laryngospasm, stridor, subglottic oedema treatment (nebulised adrenaline, dexamethasone) 2. **Link 25 (Lanz connection) + Electrical safety of operating theatre** - Lanz 25/Link 25: Anaesthetic gas machine safety - pin index system, pressure regulators, fail-safe mechanisms. Electrical safety: macroshock vs microshock, current thresholds (fibrillation at 100mA external, 180 microA internal), isolated power supply, line isolation monitor, equipotential earthing, Class I/II/III equipment, residual current device (RCD/GFCI), anti-static precautions, explosion-proof requirements 3. **Postoperative analgesia for paediatric patients - lower abdominal surgery and thoracotomy** - Lower abdominal: caudal epidural (0.25% bupivacaine 1ml/kg), TAP block (USG-guided, 0.25% bupivacaine 0.5ml/kg), ilioinguinal/iliohypogastric nerve block, wound infiltration. Thoracotomy: thoracic epidural (gold standard, T4-T6 level), paravertebral block (USG-guided PVB), intercostal nerve blocks, PECS block, serratus anterior block, cryoanalgesia. Include drug doses for paediatric patients and age-specific considerations. SEARCH INSTRUCTIONS: - Use headings_fts and paragraphs_fts to find relevant sections - SQL examples: SELECT title, book_title, '/textbooks/' || block_file_path AS file_path, line_number, para_line_ranges FROM headings_fts WHERE headings_fts MATCH 'foreign body bronchoscopy' ORDER BY rank LIMIT 5 SELECT book_title, section_heading, '/textbooks/' || block_file_path AS file_path, line_start, line_end, snippet(paragraphs_fts, 0, '>>>', '<<<', '...', 30) as snippet FROM paragraphs_fts WHERE paragraphs_fts MATCH 'electrical safety microshock' ORDER BY rank LIMIT 5 - Read the actual file content using read_file with appropriate offset and limit - Cite specific textbooks (Miller's Anaesthesia, Morgan & Mikhail, Stoelting, Paediatric Anaesthesia texts) - Provide comprehensive exam-oriented answers Return a detailed, structured answer for ALL 3 topics suitable for a DNB Post-Diploma Paper 2 exam.

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DNB Anaesthesia — Post Diploma Paper 2

Complete Exam-Ready Answers

Q1. Resuscitation in Pregnant Women + Surviving Sepsis Guidelines

Part A: Resuscitation in Pregnant Women

Physiological Changes Relevant to Resuscitation

System	Change	Relevance to CPR
Cardiac output	↑ 40–50%	Higher baseline demand
Blood volume	↑ 40–50%	More blood loss needed before haemodynamic compromise
Aortocaval compression	Uterus compresses IVC from 20 weeks	↓ venous return → ↓ CPR effectiveness in supine position
Airway	Oedema, friable mucosa, ↑ Mallampati	Difficult intubation; smaller ETT (6.5–7.0 mm)
FRC	↓ 20%	Rapid desaturation; pre-oxygenate aggressively
Gastric emptying	Delayed	Full stomach — RSI mandatory
O₂ consumption	↑ 20%	Faster desaturation during apnoea

Causes of Cardiac Arrest in Pregnancy — 4Hs, 4Ts + Obstetric Causes

Obstetric-specific: Haemorrhage (PPH), Eclampsia/pre-eclampsia, Amniotic fluid embolism (AFE), Pulmonary embolism, Magnesium toxicity, Local anaesthetic toxicity (Intralipid!), Peripartum cardiomyopathy, Sepsis

ACLS Modifications in Pregnancy (AHA Guidelines)

Standard ACLS	Modification in Pregnancy
Supine position	Left Uterine Displacement (LUD): 15–30° left tilt OR manual LUD by assistant pushing uterus leftward
IV access	Place above diaphragm (antecubital or above) — IVC compression may impair drug delivery from lower limb access
Defibrillation	Same energy as non-pregnant (200J biphasic); place pads in standard position; remove fetal monitors first
Compression depth	Same (5–6 cm) — may be harder due to breast tissue; use heel of hand
Airway	Early intubation (RSI); smaller ETT 6.5–7.0; video laryngoscope first line; Grade I–IV cricothyrotomy for CICO
Drugs	Standard ACLS drugs — epinephrine, amiodarone used as per standard protocol; do not withhold due to pregnancy
ROSC	Post-ROSC care: oxygen targets, targeted temperature management; fetal monitoring

Perimortem Caesarean Section (PMCS)

The 4-minute rule: If no ROSC within 4 minutes of cardiac arrest → initiate PMCS; aim for delivery by 5 minutes
Rationale: Relieves aortocaval compression → ↑ venous return → improves CPR efficacy for the mother (not just fetal survival)
Location: Do NOT transfer to OT — perform at bedside in resuscitation area
Technique: Midline vertical incision; classical uterine incision; no anaesthesia required (mother in arrest); continue CPR throughout
Gestational age: Beneficial from 20 weeks (uterus causes compression); fetal viability from 23–24 weeks
Do not stop resuscitation after PMCS; continue on the emptied uterus

"Successful resuscitation of the pregnant patient... requires performance of PMCS within 5 minutes of cardiac arrest onset... The primary indication for PMCS is to relieve aortocaval compression and improve CPR effectiveness for the mother." — Miller's Anesthesia 10e

Part B: Surviving Sepsis Guidelines (SSC 2021)

Definitions (Sepsis-3, 2016)

Sepsis: Life-threatening organ dysfunction caused by dysregulated host response to infection (SOFA score ≥2)
Septic shock: Sepsis + vasopressor requirement to maintain MAP ≥65 mmHg + serum lactate >2 mmol/L despite adequate fluid resuscitation
qSOFA (bedside screening): RR ≥22, altered mentation, SBP ≤100 — score ≥2 = high risk

The Hour-1 Bundle (SSC 2018/2021)

Step	Action
1. Measure lactate	If lactate >2 mmol/L → measure serial lactates; target normalisation
2. Blood cultures	Obtain before antibiotics (2 sets — aerobic + anaerobic)
3. Broad-spectrum antibiotics	Administer within 1 hour of recognition
4. IV fluids	30 mL/kg crystalloid (normal saline or Ringer's lactate) bolus for hypotension or lactate ≥4 mmol/L
5. Vasopressors	If MAP <65 mmHg during/after fluids → norepinephrine first line

Fluid Resuscitation

Initial: 30 mL/kg crystalloid within 3 hours
Reassess after each bolus: dynamic fluid responsiveness (PLR, PPV, SVV) preferred over static markers (CVP)
Balanced crystalloids (Ringer's lactate, Plasmalyte) preferred over normal saline (reduces hyperchloraemic acidosis and AKI risk — SMART trial)
Albumin: Consider as adjunct when large volumes of crystalloid needed; 4% or 5% albumin
Avoid starches (HES) — increased AKI and mortality

Vasopressors

Agent	Role	Dose
Norepinephrine	First line	0.01–3 mcg/kg/min
Vasopressin	Add second to ↓ norepinephrine dose	0.03 units/min fixed
Epinephrine	Third line OR when cardiac dysfunction present	0.01–0.3 mcg/kg/min
Dopamine	NOT recommended routinely	Only if bradycardia with low CO
Dobutamine	When myocardial dysfunction with low CO	2–20 mcg/kg/min

Antibiotics

Timing: Within 1 hour of sepsis recognition
Empirical: Broad-spectrum covering Gram-positive, Gram-negative, and anaerobes
De-escalation: As soon as culture results available (typically 48–72h)
Duration: 7–10 days; procalcitonin-guided de-escalation recommended

Source Control

Identify and drain/debride source within 6–12 hours of recognition (empyema, abdominal abscess, necrotising fasciitis)
Remove infected devices (lines, catheters)

Corticosteroids

Hydrocortisone 200 mg/day (50 mg IV q6h or 200 mg continuous infusion) if norepinephrine dose ≥0.25 mcg/kg/min for ≥4 hours without adequate MAP response
NOT for general sepsis without refractory shock
Taper when vasopressors no longer required

Mechanical Ventilation (ARDS in Sepsis)

Tidal volume: 6 mL/kg IBW
Plateau pressure: <30 cmH₂O
Prone positioning: if P:F ratio <150 for ≥12–16 hours/day
PEEP: Higher PEEP strategy for moderate-severe ARDS
Avoid routine early neuromuscular blockade

Glycaemic Control

Target blood glucose <10 mmol/L (180 mg/dL) — not tight control (<6.1 mmol/L = harm)

DVT Prophylaxis, Stress Ulcer Prophylaxis

UFH/LMWH for DVT; PPIs if risk factors for GI bleeding

Q2. Liver Function Tests and Significance + Child-Pugh Score

Part A: Liver Function Tests (LFTs)

The liver performs 3 main functions: synthesis, excretion (bile), and detoxification. LFTs reflect these:

Tests of Hepatocellular Damage (Enzymes Leaked)

Test	Normal Value	Significance
ALT (Alanine aminotransferase)	7–40 U/L	Most specific for hepatocellular damage; predominantly hepatic; markedly ↑ in viral hepatitis, drug toxicity
AST (Aspartate aminotransferase)	10–40 U/L	Less specific (also in muscle, heart, kidney); ↑ in hepatocellular damage, MI, muscle disease
AST:ALT ratio	<1 normally	>2:1 = alcoholic hepatitis (De Ritis ratio); >3:1 strongly suggests alcohol; <1 = viral/NAFLD
LDH	100–200 U/L	Non-specific; ↑ in haemolysis, liver disease, malignancy

Tests of Cholestasis (Biliary Obstruction)

Test	Normal Value	Significance
ALP (Alkaline phosphatase)	30–120 U/L	↑↑ in cholestasis, biliary obstruction, infiltrative liver disease; also ↑ in bone disease (Paget's, bone metastases), pregnancy
GGT (Gamma-glutamyltransferase)	5–55 U/L	Confirms hepatic origin of ↑ALP (bone disease does NOT ↑GGT); ↑ by alcohol, drugs (phenytoin, rifampicin); most sensitive indicator of alcohol use
Bilirubin (total)	<17 μmol/L	Jaundice apparent when >35 μmol/L
→ Direct (conjugated)	<4 μmol/L	↑ in cholestasis, hepatocellular disease; water-soluble, excreted in urine → dark urine
→ Indirect (unconjugated)	<12 μmol/L	↑ in haemolysis, Gilbert's syndrome, Crigler-Najjar; not water-soluble

Tests of Synthetic Function

Test	Normal Value	Significance
Albumin	35–50 g/L	Best marker of chronic liver synthetic function; t½ = 20 days; ↓ in cirrhosis, malnutrition, nephrotic syndrome; does NOT reflect acute liver failure
PT/INR	PT 11–14 sec; INR <1.2	Reflects acute synthetic function (factors II, VII, IX, X — Vit K dependent; factor V — not Vit K dependent); best marker in acute liver failure; ↑ INR in liver failure AND Vit K deficiency (differentiate: give Vit K — corrects if deficiency, not if liver failure)
Total protein	60–80 g/L	↓ in severe liver disease; includes albumin + globulins

Pattern Recognition Table

Pattern	ALT/AST	ALP/GGT	Bilirubin	Albumin	PT
Hepatocellular	↑↑↑	Normal or mild ↑	↑	↓ (chronic)	↑
Cholestatic	Mild ↑	↑↑↑	↑↑ (direct)	Normal	Normal
Cirrhosis	Mild ↑	↑	↑	↓↓	↑↑
Alcoholic hepatitis	↑ (AST>ALT, ratio >2)	↑ GGT	↑	↓	↑
Haemolysis	Normal	Normal	↑ (indirect)	Normal	Normal

Anaesthetic Significance of LFTs

Albumin <25 g/L: ↑ free drug fraction of protein-bound drugs (thiopentone, propofol, benzodiazepines, opioids) → exaggerated effect
↑ INR: Coagulopathy → epidural/spinal contraindicated if INR >1.5; FFP/Vit K before surgery
↑ Bilirubin: Hepatorenal syndrome risk postoperatively; bilirubin >170 μmol/L → poor prognosis
↑ AST/ALT >3× normal: Elective surgery should be postponed in acute hepatitis
Volatile agents: Halothane hepatotoxicity (immune-mediated); sevoflurane preferred (hepatic blood flow best preserved)

Part B: Child-Pugh Score

Developed by Child and Turcotte (1964), modified by Pugh (1972) — assesses severity of chronic liver disease and predicts surgical risk.

Scoring Table

Parameter	1 point	2 points	3 points
Bilirubin (μmol/L)	<34	34–50	>50
Albumin (g/L)	>35	28–35	<28
PT prolongation (seconds above normal)	<4	4–6	>6
Ascites	None	Mild (diuretic-controlled)	Moderate–severe (tense)
Hepatic encephalopathy	None	Grade I–II	Grade III–IV

Classification and Mortality

Class	Total Score	Surgical Mortality	1-year survival	2-year survival
A (compensated)	5–6	5–10%	100%	85%
B (significant compromise)	7–9	25–30%	80%	60%
C (decompensated)	10–15	70–80%	45%	35%

MELD Score (Model for End-stage Liver Disease) — Modern Alternative

Formula: 3.78 × ln[bilirubin mg/dL] + 11.2 × ln[INR] + 9.57 × ln[creatinine mg/dL] + 6.43
Score >15: Significant mortality risk with surgery
Score >20: Major surgery carries very high mortality; consider hepatic transplantation assessment
Advantages over Child-Pugh: Objective (no subjective ascites/encephalopathy grading), better predicts 90-day mortality

Anaesthetic Implications by Child-Pugh Class

Class	Key Concerns	Anaesthetic Approach
A	Minimal compromise	Standard anaesthesia; monitor LFTs post-op
B	Coagulopathy, ↓ albumin, mild portal hypertension	Avoid hepatotoxic drugs; minimise hepatic blood flow disruption; cautious fluid; check clotting pre-op
C	Severe: encephalopathy, ascites, varices, coagulopathy, hepatorenal syndrome risk	High-risk; multidisciplinary planning; regional preferred if coagulation allows; ICU post-op; avoid GA if possible

Drug considerations in liver disease:

Sevoflurane — preferred volatile (maintains hepatic blood flow; minimal biotransformation)
Avoid halothane (hepatotoxicity), NSAIDs (hepatorenal), benzodiazepines (accumulate)
Propofol — relatively safe; extra-hepatic metabolism
Atracurium/cisatracurium — preferred NMBDs (Hofmann elimination; independent of liver/kidney)
Morphine — ↑ bioavailability; ↑ half-life; use with caution; fentanyl safer for short procedures
Neostigmine — slightly prolonged effect; monitor NMT

Q3. USG-Guided Adductor Canal Block + Renal Replacement Therapy

Part A: USG-Guided Adductor Canal Block (ACB)

Anatomy of the Adductor Canal

The adductor canal (Hunter's canal / subsartorial canal) is a musculoaponeurotic tunnel in the middle third of the thigh.

Boundaries:

Wall	Structure
Roof (anteromedial)	Sartorius muscle + vastoadductor membrane
Lateral	Vastus medialis
Posteromedial floor	Adductor longus → adductor magnus

Contents:

Superficial femoral artery (SFA)
Superficial femoral vein (SFV)
Saphenous nerve — purely sensory terminal branch of femoral nerve; supplies medial knee, leg, ankle
Nerve to vastus medialis (VMCN) — mixed nerve; motor to VMO + sensory to knee joint; lies lateral to SFA
Posterior division of obturator nerve — variable; contributes to knee analgesia

Sonoanatomy (Transverse view, mid-thigh)

Sartorius — flat, triangular hypoechoic muscle = roof of canal
Vastoadductor membrane — echogenic double-contour line
SFA — round, pulsatile, non-compressible (confirm with colour Doppler)
SFV — compressible, medial to SFA
Saphenous nerve — small hyperechoic oval, anterolateral to SFA
VMCN — just lateral to SFA in own fascial plane

Technique

Step	Detail
Position	Supine, thigh externally rotated, leg extended
Probe	High-frequency linear (10–15 MHz), transverse orientation
Level	Mid-thigh (midpoint ASIS to superior patellar pole)
Approach	In-plane, lateral-to-medial
Target	Deep to sartorius, lateral to SFA, deep to vastoadductor membrane
Volume	15–20 mL
Drug	Ropivacaine 0.5% or Bupivacaine 0.5% ± dexamethasone
Aspiration	Mandatory before injection (SFA and SFV adjacent)

ACB vs Femoral Nerve Block (FNB)

Feature	ACB	FNB
Quadriceps strength	Preserved (motor-sparing)	Significantly reduced
Ambulation Day 1	Earlier, safer mobilisation	Limited by quad weakness
Fall risk	Lower	Higher
Analgesia for TKR	Non-inferior	Excellent but costly (motor block)

"Patients with continuous adductor canal catheters are able to ambulate further on the first day following total knee arthroplasty than patients with femoral block." — Morgan & Mikhail 7e

Why quadriceps spared: ACB is at mid-thigh where femoral nerve is purely sensory; motor branches to quadriceps arise proximally in the femoral triangle.

Complications

Intravascular injection (SFA/SFV proximity)
Vascular injury/pseudoaneurysm
Quadriceps weakness (volumes >15 mL or high block)
Block failure

Part B: Renal Replacement Therapy (RRT)

Indications — Mnemonic AEIOU

Letter	Indication	Threshold
A	Metabolic Acidosis	pH <7.1 refractory to medical therapy
E	Electrolytes	Hyperkalemia K⁺ >6.5 mEq/L refractory to medical Rx; severe hyponatremia
I	Intoxication	Dialyzable toxins: lithium, salicylates, methanol, ethylene glycol, theophylline
O	Fluid Overload	Pulmonary oedema refractory to diuretics; oliguria/anuria
U	Uraemia	BUN >100 mg/dL symptomatic (encephalopathy, pericarditis, platelet dysfunction)

Modalities of RRT

Modality	Mechanism	Duration	Haemodynamics	Best For
IHD (Intermittent Haemodialysis)	Diffusion	3–4 h, 3×/week	Needs stability (risk of intradialytic hypotension)	Stable outpatients
SLED/PIRRT	Slow diffusion	6–18 h/day	Better tolerated than IHD	Intermediate stability
CVVH	Convection only	24 h continuous	Excellent for instability	ICU, haemodynamic compromise
CVVHD	Diffusion only	24 h continuous	Excellent	ICU
CVVHDF	Diffusion + Convection	24 h continuous	Excellent	Optimal solute clearance in ICU
PD	Peritoneal diffusion	Continuous	Safe	Limited access settings, children

IHD vs CRRT Key Differences

	IHD	CRRT
Solute clearance	Rapid, fluctuating	Slow, steady
Volume removal	Rapid	Gradual, precise
Vasopressors	Contraindicated	Compatible
Drug clearance	Unpredictable	Predictable, continuous
Cost	Lower	Higher

Anticoagulation for CRRT

Regional Citrate Anticoagulation (RCA) — Preferred
- Citrate infused pre-filter → chelates Ca²⁺ → anticoagulation in circuit only
- Post-filter Ca²⁺ replacement given systemically
- No systemic bleeding risk
- Complication: Citrate toxicity in liver failure → ↑ total-to-ionized Ca²⁺ ratio, metabolic alkalosis, hypocalcaemia
Unfractionated Heparin (UFH)
- 100–500 units/h pre-filter
- Target aPTT 40–60 sec
- Contraindicated in HIT, active bleeding

CRRT Dose

Effluent rate: 20–25 mL/kg/h (prescribe 25–30 mL/kg/h to account for downtime)
IHD: Kt/V ≥1.2–1.4 per session

Timing of Initiation

No mortality benefit to early initiation (AKIKI, IDEAL-ICU, STARRT-AKI trials)
Initiate when AEIOU criteria met
Do NOT delay until BUN >140 mg/dL (AKIKI-2: HR 1.60 for mortality with ultra-late initiation)
29% of "watchful waiting" group in IDEAL-ICU never required RRT

Q4. Types of Labour Analgesia + Pain Pathway in Labour Pain

Part A: Pain Pathway in Labour

First Stage of Labour (Cervical Dilatation + Uterine Contractions)

Pain type: Visceral — poorly localised, cramping, referred
Afferents: Thin unmyelinated C fibres (and some Aδ)
Pathway: Uterine body/fundus/cervix → uterovaginal plexus (Frankenhäuser's plexus) → inferior hypogastric plexus → sympathetic chain at T10, T11, T12, L1
Referred pain: T10–L1 dermatomes → lower abdomen, back, groin
Character: Intermittent with contractions; perceived even between contractions in active labour

Second Stage of Labour (Descent + Perineal Distension)

Pain type: Somatic — sharp, well-localised
Afferents: Myelinated Aδ fibres
Pathway: Vagina, perineum, vulva → pudendal nerve → S2, S3, S4
Character: Constant burning/tearing; pressure; urge to push

Summary of Dermatomal Levels for Complete Labour Analgesia

Stage	Nerve Fibres	Dermatomes
1st stage	Visceral (C fibres)	T10 – L1
2nd stage	Somatic (Aδ via pudendal)	S2 – S4
Complete epidural analgesia	—	T10 – S4

Part B: Types of Labour Analgesia

1. Epidural Analgesia — Gold Standard

Technique:

Position: Sitting or left lateral decubitus; flex spine maximally
Level: L2–L3 or L3–L4 interspace
Identify epidural space: Loss of resistance (LOR) to saline or air; depth ~4–6 cm from skin
Thread epidural catheter 3–5 cm into space
Test dose: 3 mL lignocaine 2% + adrenaline 1:200,000 (tachycardia = intravascular; spinal block = intrathecal)
Maintenance: PIEB (Programmed Intermittent Epidural Bolus) ± PCEA (Patient-Controlled Epidural Analgesia) — PIEB superior to CEI (continuous infusion)

Drug regime:

Low-dose: 0.0625–0.1% bupivacaine + fentanyl 2 mcg/mL (motor-sparing, ambulation possible)
Bolus: 10–15 mL, then PIEB 10 mL every 40–60 min ± PCEA 5–10 mL lock-out 15–20 min

Advantages: Titratable, can be extended for CS, excellent analgesia, no fetal drug effect
Disadvantages: Motor block (dose-dependent), hypotension, pruritus (fentanyl), headache if dural puncture, backache, fever (epidural pyrexia)

2. Combined Spinal-Epidural (CSE)

Needle-through-needle technique: spinal needle through epidural needle into CSF
Intrathecal dose: Bupivacaine 1.25–2.5 mg + fentanyl 15–25 mcg ± morphine 0.1–0.2 mg
Onset: Rapid (2–5 minutes) — advantage for advanced labour
Duration: Spinal component lasts 60–90 min; epidural catheter used thereafter
Advantages: Rapid onset, lower local anaesthetic dose, better analgesia for 2nd stage (denser block possible)
Disadvantages: Cannot test epidural catheter until spinal wears off; fetal bradycardia reported (possibly from rapid analgesia → oxytocin surge → uterine hypertonus)

3. Dural Puncture Epidural (DPE)

Spinal needle punctures dura without intrathecal injection; epidural catheter placed
LA administered epidurally — enhanced spread through dural hole
Better sacral coverage than standard epidural; less risk than CSE

4. Spinal (Single-Shot)

Used for CS; not practical for labour (too short duration, cannot redose)
Saddle block: hyperbaric bupivacaine for perineal analgesia in 2nd stage

5. Systemic Opioids

Drug	Route	Notes
Entonox (50% N₂O + 50% O₂)	Inhalational self-administered	Fast onset/offset; reduces pain perception 30–40%; nausea, dizziness; bone marrow (chronic use); methionine synthetase inhibition
Remifentanil PCA	IV bolus (20–40 mcg, lock-out 2 min)	Ultra-short acting (t½ 3–4 min); effective; risk of apnoea → continuous SpO₂, 1:1 midwife monitoring mandatory
Pethidine (Meperidine)	IM 75–100 mg	Widely used; metabolite norpethidine — neonatal respiratory depression; nausea common; 4-hour window before delivery advised
Fentanyl	IV/IM	Rapid onset; minimal neonatal accumulation vs pethidine
Nalbuphine, Butorphanol	IV/IM	Mixed agonist-antagonist; ceiling effect; nausea

6. Regional Blocks

Paracervical Block:

Injection of LA at 3 o'clock and 9 o'clock at cervicouterine junction
Blocks visceral afferents (1st stage)
Complication: Fetal bradycardia (5–10%) — direct fetal injection or uterine artery spasm; now rarely used

Pudendal Block:

Landmark or USG-guided injection near ischial spine bilaterally
Blocks pudendal nerve (S2–S4)
Covers perineum, vulva, vagina — 2nd stage and episiotomy repair
10 mL lignocaine 1% each side
Complications: intravascular injection, haematoma

7. Contraindications to Neuraxial Analgesia

Absolute: Patient refusal, local infection at insertion site, uncorrected hypovolaemia, coagulopathy (INR >1.5, platelets <80,000, therapeutic anticoagulation), raised ICP with space-occupying lesion

Relative: Fixed cardiac output states (severe AS), back deformity, previous spinal surgery, thrombocytopenia (platelets 80,000–100,000 — clinical judgement)

Q5. Anaesthesia Challenges and Management of Posterior Fossa Tumour

Positioning

Sitting Position

Advantages: Best surgical exposure, optimal venous drainage, reduced brain retraction
Disadvantages/Complications:

Venous Air Embolism (VAE) — 20–40% by Doppler; highest risk of any surgical position
Paradoxical Air Embolism (PAE) via PFO (~25% prevalence)
Haemodynamic instability (venous pooling → ↓ preload)
Tension pneumocephalus
Macroglossia (neck flexion → venous obstruction)
Cervical spinal cord injury (excessive neck flexion)
Quadriplegia risk if pre-existing cervical spondylosis

Pre-requisites before sitting position:

Screen for PFO (bubble echocardiography / TCD)
Confirm neck flexion safe (2–3 finger-breadths chin-to-chest)
Multi-orifice right heart catheter for air aspiration
Precordial Doppler + ETCO₂

Prone Position: Lower VAE risk (12%), haemodynamically stable, but restricted access

Venous Air Embolism (VAE)

Detection — Sensitivity Order (Most to Least Sensitive)

Monitor	Sensitivity	Comment
TEE	Highest (0.02 mL/kg)	Detects PFO; PAE visible; cardiac function; expensive/invasive
Precordial Doppler	Very high (0.25 mL)	Standard of care; non-invasive; hissing → roaring sound
ETCO₂	Moderate	Sudden ↓ ETCO₂ = ↑ dead space (dilution by air)
Pulmonary artery pressure	Moderate	PAP rises with air embolism
CVP	Late	Rises late
BP/ECG/Mill-wheel murmur	Very late	Only massive embolism

Treatment of VAE — Stepwise

Notify surgeon immediately → flood/pack field with saline, bone wax to skull edges
Bilateral jugular vein compression → ↑ cerebral venous pressure → identifies entry site
Aspirate right heart catheter (multi-orificed CVP catheter)
Discontinue N₂O → FiO₂ 1.0 (N₂O diffuses into air bubbles, expands volume)
Lower head if possible
Vasopressors/inotropes for haemodynamic support
Volume loading to ↑ CVP
Chest compressions if cardiac arrest

⚠️ PEEP is CONTRAINDICATED — reverses RA–LA pressure gradient → increases PAE risk through PFO

ICP Management

Intervention	Effect
Head-up 15–30°	↓ ICP, ↑ venous drainage
PaCO₂ target 35 mmHg	Moderate hyperventilation for brain relaxation
Mannitol 0.5–1 g/kg	Osmotic agent; onset 30 min; duration 4–6 h
Hypertonic saline (3–23.4%)	Osmotic; maintain Na 145–155 mEq/L
Dexamethasone	Reduces peritumoral vasogenic oedema (not cytotoxic)
Avoid N₂O	Expands pneumocephalus; worsens VAE
Maintain CPP >60 mmHg	CPP = MAP − ICP
EVD	For obstructive hydrocephalus

Intraoperative Neurophysiological Monitoring (IONM)

Modality	What Monitored	Anaesthetic Constraint
SSEPs	Dorsal column / sensory pathway	Volatile agents ↓ amplitude dose-dependently
MEPs	Corticospinal tract	No NMB (or constant partial block <5% twitch); volatile ↑ latency
BAERs	Acoustic nerve, brainstem auditory pathway	Least affected by anaesthesia
CN VII EMG	Facial nerve	Critical for acoustic neuroma; absolutely no NMB
CN IX/X EMG	Glossopharyngeal/vagus	Swallowing/airway
CN XII EMG	Hypoglossal	Tongue/airway post-op

Preferred anaesthetic for IONM: TIVA (propofol + remifentanil) — minimal MEP/SSEP suppression; avoid volatile agents >0.5 MAC; avoid N₂O

Specific Concerns: Brainstem Stimulation

Manipulation near pons/medulla → autonomic surges: bradycardia + hypotension OR tachycardia + hypertension + dysrhythmias. Continuous arterial line + ECG essential. Communicate with surgeon if sustained changes occur.

Extubation Decision

Extubate if: Fully awake, following commands, intact CN IX/X/XII, haemodynamically stable, no airway oedema
Delay extubation (ICU intubated) if: CN IX/X/XII dysfunction (aspiration risk, airway loss), brainstem swelling, large tumour resection, prolonged surgery, pneumocephalus, haemodynamic instability

Post-op Complications

Haemorrhage/oedema → herniation
Tension pneumocephalus ("Mount Fuji sign" on CT — bilateral subdural air with frontal lobe compression)
CSF leak, meningitis
Hydrocephalus
Cranial nerve deficits (VII — facial palsy, VIII — hearing loss, IX/X — swallowing/aspiration, XII — tongue/airway)
Cerebellar mutism (children)

Q6. Airway Management of Maxillofacial Trauma + Manual Inline Stabilisation (MILS)

Initial Assessment

LEMON criteria + maxillofacial-specific:

Active haemorrhage, trismus (spasm vs mechanical), disrupted anatomy, blood/debris in airway, cervical spine injury (co-exists in 1.2–10.8% of maxillofacial trauma)

LeFort Fracture Classification and Airway Implications

Fracture	Description	Airway Implication
LeFort I	Horizontal fracture, maxilla above nasal floor	Oral intubation preferred
LeFort II	Pyramidal; may involve cribriform plate	⚠️ Nasal intubation contraindicated
LeFort III	Craniofacial dysjunction; "dish face"	⚠️ Nasal intubation absolutely contraindicated — ETT may enter cranium
Panfacial	Combined mandible + midface + frontal	Tracheostomy often required

Airway Decision Tree

MAXILLOFACIAL TRAUMA
    ↓
Can oxygenate/ventilate? → NO → EMERGENCY SURGICAL AIRWAY (cricothyroidotomy)
    ↓ YES
Anticipated difficult airway?
    ↓ YES → AWAKE technique (Awake FOI / Awake VL / Awake surgical airway)
    ↓ NO
RSI + MILS + Videolaryngoscope (preferred over DL)

Manual Inline Stabilisation (MILS)

Purpose: Minimise C-spine movement during laryngoscopy
Technique:

Assistant stands at patient's side, facing patient
Hands on mastoid processes and occiput
No traction — maintains neutral alignment
Remove cervical collar temporarily (collar restricts mouth opening)
Thumbs may brace lower jaw to prevent extension

Effect on laryngoscopy:

Worsens Cormack-Lehane grade (prevents atlanto-occipital extension)
↑ failed first-pass intubation with DL
Videolaryngoscopy (VL) preferred — does not require neck extension for view

"MILS does not apply traction — it provides neutral alignment. Traction would worsen an unstable injury."

Airway Techniques

Technique	Indication	Notes
Videolaryngoscopy	RSI + MILS	First choice post-RSI; GlideScope, C-MAC, McGrath
Awake fibreoptic (AFOI)	Predicted difficult, C-spine injury	Oral approach (LeFort II/III → no nasal FOI); topical LA + dexmedetomidine
Cricothyroidotomy	CICO (cannot intubate, cannot oxygenate)	Scalpel-bougie-tube (SAFELY technique); 4 mm ID minimum
Retrograde intubation	Difficult oral access, no FOB	Wire via cricothyroid → oral/nasal exit → guide ETT
Tracheostomy	Panfacial, laryngotracheal disruption, long-term	Awake under LA; convert emergency cric within 24–72h

Intraoperative Considerations

Throat pack: Document clearly; remove before jaw wiring or extubation
IMF (intermaxillary fixation): Wire cutters at bedside; patient cannot open mouth post-op
ETT secured meticulously (head turned 90–180° from anaesthesiologist)
Extubate awake, fully reversed, sitting up; airway exchange catheter as bridge if uncertain

Q7. Anaesthesia Management of 2-Year-Old with Foreign Body (Emergency)

Preoperative Assessment

History: Type and location of FB (radiopaque/lucent on CXR), duration, respiratory symptoms (wheeze, stridor, decreased air entry), time of last meal (full stomach in emergency)
Examination: SpO₂, respiratory rate, degree of respiratory distress, unilateral wheeze (right main bronchus most common — right bronchus more vertical)

Paediatric Airway Equipment for 2-year-old (weight ~12 kg):

Equipment	Size
ETT (uncuffed)	4.5 mm ID (age/4 + 4 = 4.5)
ETT (cuffed)	4.0 mm
LMA	Size 2 (10–20 kg)
Laryngoscope blade	Miller 1 (straight, preferred for infant/toddler)
Rigid bronchoscope	Age-appropriate (Karl Storz or equivalent)
Suction catheter	8 Fr

Induction Strategy — The Core Debate

Inhalational Induction with Spontaneous Ventilation (Traditional)

Sevoflurane in 100% O₂; maintain spontaneous breathing
Rationale: Ball-valve FB — IPPV may push FB distally; spontaneous ventilation safer
Drug: Sevoflurane 6–8% induction, reduce to 3–5% maintenance; avoid N₂O (risk of expanding gas distal to FB)
Adjunct: Dexmedetomidine 0.5–1 mcg/kg IV (reduces volatility requirement, better conditions, no respiratory depression)
Anti-sialagogue: Atropine 0.02 mg/kg IV (reduces secretions, prevents bradycardia)

IV Induction + Controlled Ventilation

Propofol (3–4 mg/kg) ± remifentanil + succinylcholine for rigid bronchoscopy
Concern: IPPV may worsen air trapping distal to ball-valve FB
Use if: Child in extremis, cannot maintain SpO₂, needs rapid airway control

Current Recommendation (Evidence-Based)

Balanced approach: IV propofol induction (smooth, rapid) + maintain spontaneous ventilation with TIVA (propofol infusion ± remifentanil); avoid volatile during bronchoscopy (leakage through rigid scope)
Avoid neuromuscular blockade until FB is visualised and not causing ball-valve obstruction, OR use short-acting (mivacurium) if needed for bronchoscopy

Rigid Bronchoscopy Technique

Ventilation during rigid bronchoscopy:

Spontaneous ventilation through bronchoscope side-arm (preferred for FB)
Venturi jet ventilation — high-pressure jet through side port; risk: barotrauma, gas trapping distal to FB; use cautiously
Apnoeic oxygenation for brief FB retrieval

Intraoperative monitoring: Continuous SpO₂, ETCO₂, ECG, NIBP; prepare for complete obstruction during manipulation (have plan: remove bronchoscope, mask ventilate, RSI/surgical airway)

Post-Operative Concerns

Complication	Management
Laryngospasm	100% O₂, jaw thrust, propofol 0.5 mg/kg or succinylcholine 1–2 mg/kg
Stridor	Nebulised adrenaline (1 mL of 1:1000 in 4 mL saline); dexamethasone 0.25–0.5 mg/kg IV
Subglottic oedema	Humidified O₂, adrenaline nebulisation, dexamethasone, ICU observation
Bronchospasm	Salbutamol MDI via adaptor, IV aminophylline
Residual FB	Repeat bronchoscopy

Post-op: Nurse head-up; monitor SpO₂ for 4–6 hours; CXR post-procedure; ICU if any respiratory compromise

Q8. Biochemical Changes of Stored Blood + Indications and Complications of Blood Transfusion

Part A: Biochemical Changes of Stored Blood (Storage Lesion)

Blood stored in CPDA-1 at 1–6°C; shelf life 42 days

Progressive Changes

Parameter	Change	Clinical Significance
pH	↓ to 6.79	Metabolic acidosis; however citrate metabolism post-transfusion → alkalosis
pCO₂	↑ to ~79 mmHg	CO₂ accumulation
K⁺ (plasma)	↑ to ~20 mmol/L by 42 days	Hyperkalaemia risk — neonates, renal failure, rapid/massive transfusion
2,3-DPG	↓ (depleted by 7–14 days)	Left shift of O₂-Hb dissociation curve → ↑ Hb-O₂ affinity → ↓ O₂ delivery to tissues; regenerates within 24h post-transfusion
ATP	↓	RBC shape change (echinocytes), ↓ deformability, ↑ haemolysis
Lactic acid	↑ to 9.4 mmol/L	Acidosis
Citrate	High concentration	Chelates ionized Ca²⁺ → hypocalcaemia during massive transfusion
Microaggregates	↑ (WBC/platelet debris 20–200 μm)	Pulmonary microvascular obstruction; removed by microfilters
Nitric oxide	↓	Vasoconstriction, impaired microcirculation
Glucose	↑ initially, ↓ late

Clinical Implications: The "lethal triad" of massive transfusion = Hypothermia + Acidosis + Coagulopathy

Part B: Indications for Transfusion

Haemoglobin Triggers

Clinical Setting	Hb Trigger	Evidence
General ICU (critically ill)	7 g/dL (restrictive)	TRICC trial; 2022 Cochrane review (48 RCTs, 21,000 patients)
Cardiovascular surgery	8 g/dL	TRICS-III trial
Hip fracture / orthopaedic	8 g/dL	FOCUS trial
Acute MI / ACS	8 g/dL	MINT trial
Massive haemorrhage	Clinical + 1:1:1 protocol	Damage control resuscitation

Massive Transfusion Protocol (MTP)

Definition: ≥10 units PRBCs in 24h OR ≥4 units in 1 hour
Ratio: 1:1:1 (PRBCs : FFP : Platelets)
Cryoprecipitate: fibrinogen <1.5 g/L
Tranexamic acid (TXA): 1g IV within 3 hours of injury (CRASH-2 trial)
Goal-directed with TEG/ROTEM
Avoid hypothermia (warm blood); avoid acidosis; replace calcium

Part C: Complications of Blood Transfusion

Immune Complications

Complication	Frequency	Timing	Mechanism	Management
Acute haemolytic	1:25,000	Immediate	ABO incompatibility (clerical error)	Stop transfusion; fluids; forced diuresis (mannitol); monitor for DIC; renal protection
Delayed haemolytic	1:12,000	2–21 days post	Rh/Kidd/Kell/Duffy alloantibodies	Supportive; crossmatch
FNHTR	1–3%	During/after	Anti-WBC/platelet antibodies	Slow/stop; antipyretics; use leukoreduced blood
TRALI	1:5,000	Within 6h	HLA antibodies in donor plasma (multiparous females) → neutrophil sequestration in lung	Supportive ventilation (ARDS protocol); usually resolves; use male-only donors for plasma
TACO	1:100	During/after	Volume/rate overload → cardiogenic pulmonary oedema	Diuretics; slow rate; sitting position
Allergic/urticaria	1%	Immediate	Plasma protein sensitisation	Antihistamines; continue slowly
Anaphylaxis	1:150,000	Immediate	IgA-deficient patient + anti-IgA	Adrenaline; steroids; antihistamines; use IgA-free products in future
GvHD	Rare	10–30 days	Donor T lymphocytes attack host	Prevention: irradiation (not leukoreduction alone) in immunocompromised

TRALI vs TACO distinction:

	TRALI	TACO
Mechanism	Non-cardiogenic	Cardiogenic (fluid overload)
BNP	Normal/low	↑ BNP
BP	Hypotension	Hypertension
PCWP	Normal	↑
Response to diuretics	No	Yes
Onset	Within 6 hours	During/just after

Metabolic Complications

Complication	Cause	Management
Hypocalcaemia	Citrate chelates Ca²⁺	CaCl₂ 10 mg/kg or calcium gluconate; monitor iCa²⁺
Hyperkalaemia	K⁺ ~20 mEq/L in stored blood	Calcium; slow infusion; wash blood for neonates/renal failure
Hypothermia	Cold blood (1–6°C)	Blood warmers (mandatory for massive transfusion)
Dilutional coagulopathy	PRBCs without clotting factors	1:1:1 ratio; cryoprecipitate; TEG-guided
Metabolic alkalosis	Citrate → bicarbonate	Self-resolving

Infectious Complications (per unit, with current screening)

Pathogen	Risk
HIV	1:1,900,000
HCV	1:1,900,000
HBV	1:200,000
Bacterial contamination (platelets highest risk)	1:2,000–5,000

Q9. Link 25 (Lanz Connection) + Electrical Safety of Operating Theatre

Part A: Link 25 (Pin Index Safety System / Lanz Connection)

"Link 25" refers to the Pin Index Safety System (PISS) — a safety feature of the anaesthetic machine preventing wrong gas cylinder connection.

Pin Index Safety System

Each medical gas cylinder has a specific pair of pins on the yoke of the anaesthetic machine
The corresponding holes on the cylinder valve match only one specific gas
Cannot physically connect a wrong gas cylinder to the wrong yoke
Standardised by the Compressed Gas Association and British Standard BS 341

Pin positions (Common Gases):

Gas	Pin Position
Oxygen	2, 5
Nitrous oxide	3, 5
Air	1, 5
CO₂	1, 6
O₂/CO₂ mixture	2, 6

Other Safety Features of Anaesthetic Machine:

Colour coding (oxygen = white/green; N₂O = blue; air = grey/white with black shoulder)
Pressure regulators — reduce cylinder pressure to working pressure
Fail-safe/oxygen failure alarm — N₂O and other gases cut off if O₂ supply fails
Hypoxic guard / anti-hypoxia device — minimum 21–25% O₂ when N₂O used (Link-25 proportioning system)
Flow meters (rotameters) — O₂ flowmeter downstream of all others
Vaporiser interlock — prevents use of >1 vaporiser simultaneously
Breathing system pressure relief valve (APL — Adjustable Pressure Limiting)
Scavenging — AGSS (Anaesthetic Gas Scavenging System)

Part B: Electrical Safety in Operating Theatre

Why Electrical Safety Matters

OT = electrically hazardous environment (wet, conductive patients, invasive devices near heart)
Risk of macroshock (external current → body → earth) and microshock (current directly to myocardium)

Current Thresholds — Most Important Table

Current (AC, 60 Hz)	Effect
1 mA	Threshold of perception
5 mA	Painful sensation
10–20 mA	"Let-go" threshold (sustained muscle contraction, cannot release)
50–100 mA	Respiratory arrest
100 mA (0.1A)	Ventricular fibrillation (macroshock — external)
1–10 A	Sustained VF + burns
180 μA (microamperes)	VF if current applied directly to myocardium (microshock)

Macroshock vs Microshock

	Macroshock	Microshock
Current path	Skin → body → heart → earth	Direct to myocardium (central line, pacing wire)
Current for VF	100 mA	180 μA (1000× less)
Cause	Equipment fault, wet hands	Intracardiac catheter contact with current leak
Prevention	Earthing, GFCI, isolated power	Isolated power supply, special "cardiac protected" areas

Isolated Power Supply (IPS)

Standard hospital outlets are connected to earth (grounded)
In an isolated power supply: power is delivered through an isolation transformer — neither conductor is connected to earth
Advantage: A single fault does not complete a circuit — no shock (current needs TWO points to ground)
Line Isolation Monitor (LIM): Continuously monitors impedance between isolated power system and earth; alarms if fault current reaches 2–5 mA (hazard threshold)
LIM alarm action: Identify and remove faulty equipment; do NOT interrupt surgery

Zone Classification (IEC 60364 / NFPA 99):

Zone	Examples	Electrical Protection
Zone 0 (general)	Corridors, waiting areas	Standard earthed supply
Zone 1 (Body protected)	Anaesthetic rooms, recovery	GFCI + equipotential bonding
Zone 2 (Cardiac protected)	Cardiac catheter labs, ICU with intracardiac devices	Isolated power supply + LIM + microshock protection

Equipotential Earthing (Grounding)

All metal objects in the OT (trolleys, anaesthetic machine, diathermy, etc.) bonded together to earth at the same potential
Prevents potential difference between equipment → no current flow through patient
All equipment connected to a common earth bus bar

Residual Current Device (RCD / GFCI)

Detects difference between current flowing in live and neutral wires (>30 mA → trips in 30 ms)
Installed in Zone 1 areas (not used in Zone 2 — isolated power used instead)
Limitation: Does not protect against microshock

Diathermy (Electrosurgical Unit — ESU) Safety

Uses high-frequency AC (radiofrequency, 300 kHz – 3 MHz) — does not cause neuromuscular excitation
Return electrode (neutral plate/dispersive electrode): Must be correctly placed (broad contact area → low current density) to prevent burns
Monopolar vs Bipolar: Bipolar safer (current limited to between forcep tips); use bipolar near pacemakers, implants
Pacemaker interaction: Use bipolar; place plate far from pacemaker; have defibrillator/magnet available

Anti-Static and Fire Prevention

OT floors and footwear: anti-static (conductive) to dissipate static charges
No longer required to be explosive-proof (flammable anaesthetic agents largely abandoned)
Modern requirements: static dissipation, not full explosion-proofing

Classes of Electrical Equipment

Class	Earth Connection	Insulation	Examples
Class I	Earthed metal body	Basic	Most OT equipment (anaesthetic machine, monitors)
Class II	No earth	Double insulation	Portable equipment, drills
Class III	Operates on SELV (<24V DC)	—	Battery-operated devices
CF (Cardiac Floating)	No earth; floating input	For cardiac applications	ECG leads on pacemaker patients; intracardiac catheters

Q10. Postoperative Analgesia for Paediatric Patients — Lower Abdominal Surgery and Thoracotomy

General Principles of Paediatric Analgesia

Multimodal analgesia: Combine regional + systemic; reduce opioid requirements
Pain assessment: FLACC scale (<4 years), Faces scale (4–8 years), NRS/VAS (>8 years)
Weight-based dosing; regular dosing better than PRN in children
Neonates/infants have immature blood–brain barrier → higher opioid sensitivity

Part A: Lower Abdominal Surgery (Inguinal hernia, Orchidopexy, Lower laparotomy, Appendicectomy, Colostomy)

1. Caudal Epidural Block — Most Common Paediatric Regional Technique

Parameter	Detail
Indication	Sub-umbilical surgeries, inguinal region, perineum
Patient position	Left lateral, knee–chest position
Landmark	Sacral hiatus (between sacral cornua) → feel "pop" through sacrococcygeal membrane
Drug	0.25% bupivacaine 1 mL/kg (max 20 mL) for sacral block; 0.5 mL/kg for sacral+lumbar
Additives	Clonidine 1–2 mcg/kg (prolongs duration to 12h); morphine 30–50 mcg/kg (24h but respiratory depression risk); dexamethasone
Duration	Bupivacaine alone ~4–6h; with clonidine ~12h
Limitations	Cannot use above umbilicus; limited by volume requirements

2. Ultrasound-Guided Transversus Abdominis Plane (TAP) Block

Parameter	Detail
Target	Fascial plane between internal oblique and transversus abdominis — T10–L1 nerves
Approach	Subcostal TAP (T8–T10), lateral TAP (T10–L1), posterior TAP (lumbar plexus branches)
Probe	High-frequency linear, transverse in mid-axillary line between iliac crest and costal margin
Drug	0.25% bupivacaine 0.5 mL/kg each side (max 2.5 mg/kg total)
Duration	8–12 hours
Advantage over caudal	No motor block; bilateral; can be done post-op; suitable above umbilicus

3. Ilioinguinal/Iliohypogastric Nerve Block

Target: L1 (ilioinguinal) and L1 (iliohypogastric)
Landmark: 1 cm medial and 1 cm superior to ASIS; inject between external and internal oblique
USG preferred (reduces failure rate from 30% to <5%)
Drug: 0.25% bupivacaine 0.1–0.2 mL/kg each side
Indication: Inguinal hernia repair, orchidopexy

4. Systemic Analgesia (Adjuncts and Non-Regional)

Drug	Dose	Notes
Paracetamol	15 mg/kg IV/oral q6h (max 60 mg/kg/day)	First-line; safe all ages
Ibuprofen	5–10 mg/kg q6–8h oral (>6 months)	Avoid in <6 months, renal impairment, post-tonsillectomy
Morphine	0.05–0.1 mg/kg IV q3–4h (>6 months)	Titrate; sedation monitoring
Fentanyl	0.5–1 mcg/kg IV (for procedural/breakthrough)	Short-acting
Ketamine (subanesthetic)	0.1–0.3 mg/kg IV bolus	NMDA antagonism; opioid-sparing; reduces central sensitisation
Dexmedetomidine	0.5–1 mcg/kg IV over 10 min	Sedation + analgesia; reduces opioid requirements

Part B: Thoracotomy (Paediatric — Congenital lung surgery, Empyema, TOF repair, Lobectomy)

Post-thoracotomy pain = severe (intercostal nerve stimulation, chest wall retraction, rib spreading → worst surgical pain)

1. Thoracic Epidural Analgesia (TEA) — Gold Standard

Parameter	Detail
Level	T4–T6 (thoracotomy incision level)
Approach	Midline or paramedian; loss of resistance to saline; cephalad catheter placement
Drug	0.1–0.125% bupivacaine + fentanyl 2 mcg/mL infusion at 0.1–0.2 mL/kg/h
Duration	Continuous infusion for 48–72 hours
Advantages	Excellent analgesia; ↓ pulmonary complications; facilitates early extubation; ↓ opioid requirements
Technical difficulty	Small epidural space; ligament flavum less distinct in infants; consider caudal catheter threaded to thoracic level in infants/neonates

Caudal-to-thoracic catheter technique (infants/neonates):

Caudal approach → thread epidural catheter cephalad under fluoroscopy/XR to T4–T6 level
Avoids direct thoracic epidural in small infants

2. Ultrasound-Guided Paravertebral Block (PVB)

Parameter	Detail
Target	Paravertebral space at T4–T6 level (each level or single injection spreads 3–4 levels)
Sonoanatomy	Transverse process, superior costotransverse ligament, paravertebral space (contains intercostal nerve)
Drug	0.25% bupivacaine 0.5 mL/kg per level (OR single injection 0.5–1 mL/kg spread over 3–4 levels); max 2.5 mg/kg
Advantage	Unilateral block; lower risk of hypotension vs thoracic epidural; haematoma risk lower; coagulopathy less of contraindication
Continuous PVB catheter	0.1–0.2 mL/kg/h bupivacaine 0.125–0.25% — equivalent to thoracic epidural for post-thoracotomy pain

3. Serratus Anterior Plane (SAP) Block

Target: Fascial plane between serratus anterior and intercostal muscles (superficial) or between serratus anterior and subscapularis (deep)
Blocks: Long thoracic nerve + lateral cutaneous branches of T2–T9
Drug: 0.25% bupivacaine 0.5 mL/kg (max 20 mL)
Advantage: Simple, safe; does not require prone position
Limitation: Anterior only; no posterior thoracotomy coverage

4. Intercostal Nerve Block

0.25% bupivacaine 0.5–1 mL per level under direct vision by surgeon
Blocks 2–3 levels above and below incision
Short duration (4–6 hours); risk of pneumothorax, systemic absorption (multiple levels)

5. Intrapleural Analgesia

LA instilled into pleural cavity via drain
Limited evidence; absorbed rapidly; not recommended as primary technique

6. Systemic Analgesia (in addition to regional)

Paracetamol + ketorolac (>6 months) scheduled
Morphine PCA/NCA (nurse-controlled analgesia for <7 years)
Ketamine infusion: 0.1–0.2 mg/kg/h — prevents central sensitisation in thoracotomy pain

Summary Table: Paediatric Post-op Analgesia

Surgery	First Choice	Alternative	Systemic Adjuncts
Lower abdominal (inguinal, scrotal, perineal)	Caudal block (0.25% bupi 1 mL/kg)	Ilioinguinal/iliohypogastric block	Paracetamol + ibuprofen
Lower laparotomy/appendix	TAP block bilateral (0.25% bupi 0.5 mL/kg/side)	Caudal with higher volume	Paracetamol + ketorolac + opioid PRN
Thoracotomy	Thoracic epidural (T4–T6, 0.1% bupi + fentanyl)	PVB (0.25% bupi 0.5 mL/kg)	Paracetamol + ketorolac + ketamine infusion

Quick Revision — Key Exam One-Liners

Q	One-Liner
Q1a	Cardiac arrest in pregnancy: LUD, above-diaphragm IV access, PMCS at 4 min → deliver by 5 min
Q1b	Surviving Sepsis Hour-1: Lactate, cultures, antibiotics (1h), 30 mL/kg fluids, norepinephrine if MAP <65
Q2a	AST:ALT >2:1 = alcohol; ALP+GGT ↑ = cholestasis; albumin = chronic synthetic; PT = acute synthetic
Q2b	Child-Pugh C (10–15) = 70–80% surgical mortality; atracurium + sevoflurane safe in liver disease
Q3a	ACB: in-plane, 15–20 mL lateral to SFA, motor-sparing = earlier ambulation after TKR vs FNB
Q3b	RRT: AEIOU indications; CRRT for vasopressor-dependent; citrate anticoagulation preferred; 20–25 mL/kg/h dose
Q4	1st stage T10–L1 (visceral/C fibres); 2nd stage S2–S4 (somatic/Aδ/pudendal); complete epidural = T10–S4
Q5	Sitting = 40% VAE; Precordial Doppler + ETCO₂ standard; NO PEEP in VAE; TIVA for IONM; no NMB for CN EMG
Q6	MILS = neutral, no traction, worsens DL → use VL; LeFort II/III = no nasal intubation; CICO = cric
Q7	2-year-old: ETT 4.5 uncuffed, LMA size 2; inhalational or propofol induction + spontaneous ventilation; no N₂O; nebulised adrenaline + dexamethasone for post-op stridor
Q8	Stored blood: pH↓, K⁺↑ (~20), 2,3-DPG↓ (left shift, regenerates 24h); TRALI within 6h non-cardiogenic; TACO = ↑BNP, responds to diuretics; 1:1:1 + TXA for massive transfusion
Q9	Pin index prevents wrong gas; LIM alarms at 2–5 mA but don't stop surgery; microshock VF at 180 μA (intracardiac) vs 100 mA macroshock; isolated power supply = Zone 2 protection
Q10	Lower abdomen: caudal 0.25% bupi 1 mL/kg; TAP block 0.5 mL/kg/side. Thoracotomy: thoracic epidural T4–T6 gold standard; PVB 0.5 mL/kg equivalent alternative

Sources: Miller's Anesthesia 10e • Morgan & Mikhail's Clinical Anesthesiology 7e • Barash Clinical Anesthesia 9e • Stoelting's Pharmacology and Physiology 5e • Smith's Anaesthesia for Infants and Children 9e • Nunn's Applied Respiratory Physiology • SSC Guidelines 2021

Find and Give answer take reference from surviving sepsis guidelines 2026

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1. a) Indications of off pump CABG. b) Technique, advantages and disadvantages of off- pump bypass. 2. a) What is preload and after load? b) What are the determinants of left ventricular diastolic function? 3. 4. 5. a) Extracorporeal membrane oxygenation. [2 times] a) Post cardiac arrest care. [5] Discuss the anesthetic considerations and perioperative management of a 75 year male who is a chronic smoker and has a permanent pacemaker in situ posted for transurethral resection of the prostate. 6. 7. 8. 9. b) Non-invasive cardiac output monitoring. b) Use of heparin during cardiopulmonary bypass. Discuss the management of ventricular tachycardia in an adult patient How will you diagnose and manage myocardial ischemia in a patient under general anaesthesia? 10. Discuss the pre, intra and post-operative management of a 53-year-old patient posted for laparoscopic cholecystectomy and detected to be hypertensive in the pre-anaesthetic clinic. [2+6+2] 11. Briefly discuss the preoperative preparation of a 65 year old female patient with coronary artery disease, with a history of drug eluting coronary stenting done one year back, posted for right total knee replacement. [10] 12. b) Cardioplegia. [5] 13. ) Cardioversion. [5] b) Aortocaval compression. 14. Discuss the pre-requisites before starting the weaning from cardiopulmonary bypass 15. Discuss the causes, diagnosis and treatment of atrial fibrillation under anaesthesia. 16. What is blood pressure, how to accurately measure it and enumerate types of hypertension? 17. Draw a labelled diagram and describe in detail the coronary circulation? How can ischemia be monitored during anaesthesia? [3 + 2] b) Discuss the factors that affect myocardial oxygen consumption and the clinical significance 18. A 26-year-old 36 week pregnant female, known case of rheumatic heart disease with severe mitral stenosis, posted for elective LSCS: a) Discuss pathophysiology of mitral stenosis. [5] b) Anesthetic plan of above patient. 19. ) Discuss the pre-anaesthetic evaluation of a 70 year old chronic smoker with systemic hypertension for 10 years on medications, posted for total hip replacement (THR) surgery 20. A 65-year-old patient posted for laparoscopic cholecystectomy, is a known case of ischemic heart disease since last 5 years: a) How will you do risk assessment/stratification of this patient? [5] b) Anesthetic management of above patient. 21. What is the role of TEE in cardiac anaesthesia? 22. a) Describe the pathophysiology of mitral stenosis. [5] b) Discuss the anaesthetic management of a 30-year-old patient with severe mitral stenosis posted for emergency appendicectomy 23. ) ACLS Algorithm for management of ventricular fibrillation. 24. ) Role of ECMO in COVID 25. Inferior venacava collapsibility index 26. Discuss the common complications that can occur after cardiopulmonary bypass surgery and their management. 27. Discuss the indications, contraindications, methods and interpretations of perioperative cardiopulmonary exercise testing. 28. What are the haemodynamic and metabolic changes associated with Aortic Cross Clamping during vascular surgery? What are the therapeutic interventions done to minimise these changes? 29. Enumerate the acyanotic and cyanotic congenital heart malformations in the newborn. [4] b) Discuss the differences between infant and adult cardiopulmonary resuscitation 30. Non invasive cardiac output monitoring. 31. Regulation of Coronary blood flow 32. Describe the factors that may lead to: [4] i) venous air embolism, and ii) arterial air embolism. b) What is paradoxical air embolism, and how does it occur? [3] c) Explain the physiological basis for the use of capnography in the detection of venous air embolism 33. How are implantable cardiac pacemakers and implantable cardioverter defibrillators classified? What information should be sought relating to these devices preoperatively? What precautions should you take perioperatively when anaesthetising patients with these devices? 34. A 65-year-old male patient is posted for total hip replacement. He has a known case of coronary artery disease (CAD) and underwent PTCA one year back, and a drug- eluting stent was placed. He was a known hypertensive and presently receiving oral aspirin, clopidogrel, atenolol and losartan as drug therapy. Discuss the preoperative assessment and anaesthetic plan for this patient. 35. Draw the Algorithm of Comprehensive Cardiopulmonary Life Support (CCLS) guidelines from the Indian Resuscitation Council Federation. Discuss the key parameters for good-quality CPR 36. A 70-year-old frail female is posted for emergency neck femur. She was diagnosed to be diabetic and hypertensive when she had primary coronary stenting for anterior wall myocardial infarction and is on NPH for last 2 years. Her recent transthoracic RS echocardiography showed EF of 50% with diastolic dysfunction. She does not have any other comorbidity. Stratify the cardiac risk, and discuss perioperative cardiac and metabolic concerns briefly including commonly used medications. 37. Temperature management following cardiac arrest from non- shockable rhythm. 38. Enumerate the causes, diagnosis and management of venous air embolism under anaesthesia 39.Elaborate about common complications encountered after CABG(10 mark)

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You are a DNB Cardiac Anaesthesia exam expert. Research ALL of the following topics from the medical library database and provide comprehensive, exam-ready answers. Use query_library_db with headings_fts and paragraphs_fts to find relevant sections, then read file content. Cite textbooks (Miller's Anaesthesia, Morgan & Mikhail, Kaplan's Cardiac Anaesthesia, Hensley's Practical Approach to Cardiac Anaesthesia, etc.) QUESTIONS TO ANSWER: **Q14. Prerequisites before starting weaning from cardiopulmonary bypass (CPB)** - Temperature (>37°C core), rhythm (sinus), haematocrit (>25%), electrolytes (K+, Ca2+, Mg2+), acid-base, ventilation restarted, surgical haemostasis, de-airing, vasopressors ready, monitoring (TEE, arterial line, CVP), inotropes if needed **Q15. Causes, diagnosis and treatment of atrial fibrillation under anaesthesia** - Causes: surgical manipulation, ischaemia, electrolyte disturbance, hypoxia, post-CPB - Rate vs rhythm control, amiodarone, beta-blockers, cardioversion, anticoagulation **Q16. What is blood pressure, how to accurately measure it, and types of hypertension** - Definition, Korotkoff sounds, cuff size requirements, ABPM, invasive arterial, white coat, masked, essential vs secondary hypertension classification **Q17. Labelled diagram and description of coronary circulation + ischemia monitoring during anaesthesia + factors affecting myocardial O2 consumption** - RCA/LCA anatomy, dominance, autoregulation, coronary perfusion pressure - Ischemia monitoring: 12-lead ECG, ST analysis, TEE (RWMA most sensitive), PA catheter - MVO2 determinants: heart rate (most important), wall tension (preload/afterload), contractility **Q18a. Pathophysiology of mitral stenosis** - Rheumatic fever, valve area (<1 cm2 severe), pressure gradient, LAP ↑, LA dilatation, AF, pulmonary hypertension, RV failure, low CO **Q18b. Anaesthetic plan for severe MS with 36-week pregnancy for LSCS** - Avoid tachycardia, maintain preload but avoid fluid overload, avoid aortocaval compression, regional (spinal with caution vs slow epidural), GA if necessary, vasopressor choice (phenylephrine), oxytocin cautiously **Q19. Pre-anaesthetic evaluation of 70-year-old chronic smoker with systemic hypertension for THR** - Cardiovascular (RCRI, functional capacity, ECG, echo if EF concern), pulmonary (PFTs, CXR, optimization), antihypertensive medication, DVT risk, anaemia correction, smoking cessation **Q20a. Risk assessment/stratification of 65-year-old with IHD for laparoscopic cholecystectomy** - ACC/AHA stepwise algorithm: emergency? → active cardiac conditions? → low risk surgery? → functional capacity ≥4 METs? → clinical risk factors (RCRI) - Lee's Revised Cardiac Risk Index (RCRI) — 6 factors, score interpretation **Q20b. Anaesthetic management of above patient** **Q21. Role of TEE in cardiac anaesthesia** - Indications (haemodynamic instability, valve surgery, aortic surgery), ASE/SCA views, what TEE can show (RWMA, EF, valvular function, air, clot, aorta), limitations **Q22a. Pathophysiology of mitral stenosis** (same as Q18a — cover completely) **Q22b. Anaesthetic management of 30-year-old with severe MS for emergency appendicectomy** - Emergency: cannot delay; RSI with ketamine caution vs etomidate; maintain HR <80; avoid tachycardia; epidural if coagulation normal; fluid cautious; vasopressors **Q23. ACLS Algorithm for VF management** - Shockable rhythm algorithm: CPR 2 min → shock 200J biphasic → CPR → epinephrine 1mg q3-5min → amiodarone 300mg → shock → CPR cycles; reversible causes 4H4T **Q24. Role of ECMO in COVID** - VVECMO for refractory ARDS (P:F <80 despite prone), ELSO criteria, outcomes **Q25. IVC Collapsibility Index** - IVC diameter measurement (M-mode), calculation: (IVCmax-IVCmin)/IVCmax × 100 - >50% = fluid responsive; <50% = not responsive; limitations (spontaneous breathing, RV failure, intraabdominal hypertension) **Q26. Common complications after CPB and their management** - Neurological (stroke, cognitive dysfunction), cardiac (LCO, arrhythmias, myocardial stunning), pulmonary (ARDS, pleural effusion), renal (AKI), haematological (coagulopathy, HIT), gastrointestinal (mesenteric ischaemia), systemic inflammatory response **Q27. Indications, contraindications, methods and interpretations of perioperative CPET** - VO2max, AT (anaerobic threshold), VE/VCO2 slope, AT <11 mL/kg/min = high risk, AT >11 = moderate, VO2 peak <15 mL/kg/min = high risk; 6-minute walk test alternative **Q28. Haemodynamic and metabolic changes with aortic cross-clamping + therapeutic interventions** - Infrarenal clamping vs supraceliac: ↑ SVR, ↑ afterload, ↑ MAP, ↓ distal blood flow; declamping: ↓ SVR, ↓ MAP, metabolic acidosis (reperfusion), myocardial depression - Interventions: vasodilators (nitroprusside, GTN), volume loading, inotropes, mannitol for kidneys, hypothermia **Q29a. Acyanotic and cyanotic congenital heart malformations** - Acyanotic: VSD, ASD, PDA, coarctation, pulmonary stenosis, aortic stenosis - Cyanotic: TOF, TGA, tricuspid atresia, truncus arteriosus, TAPVD, Ebstein anomaly **Q29b. Differences between infant and adult CPR** **Q33. Classification of pacemakers and ICDs + preoperative information + perioperative precautions** - NBG/NASPE-BPEG code (5-letter): 1st=chamber paced, 2nd=sensed, 3rd=response, 4th=rate modulation, 5th=multisite pacing - ICD classification (HRS/NASPE) - Preop info: indication, generator type, dependency, last interrogation, battery status - Periop: bipolar diathermy preferred, magnet application (converts to asynchronous DOO/VOO), CIED team involvement, deactivate ICD shock function **Q34. Preoperative assessment and anaesthetic plan for 65-year-old CAD patient with DES (1 year back), hypertensive on aspirin+clopidogrel+atenolol+losartan for THR** - Same as Q11 but more detailed: DAPT management (DES <12 months = very high risk; 1 year = continue aspirin, can stop clopidogrel 5-7 days before if bleeding risk high), ACC/AHA guidelines, bridging (NOT with UFH for stent patients), neuraxial anaesthesia timing (wait 7 days after clopidogrel stop), continue atenolol perioperatively, ACE-i/ARB (losartan) — hold on morning of surgery for non-cardiac surgery **Q35. CCLS algorithm from Indian Resuscitation Council + key parameters for good CPR** - Based on AHA 2020/BLS: compressions 100-120/min, depth 5-6 cm, full chest recoil, minimize interruptions, compression fraction >60%, capnography feedback **Q36. 70-year-old frail female for emergency neck femur — diabetic+hypertensive+coronary stenting for AWMI+NPH insulin+EF 50% with diastolic dysfunction — stratify cardiac risk + perioperative concerns** - Emergency surgery: Revised Lee's RCRI scoring, ACS risk, insulin management perioperatively (glucose 6-10 mmol/L target), diastolic dysfunction implications (avoid tachycardia, maintain sinus rhythm, adequate preload), statin continuation, beta-blocker continuation, neuraxial preference **Q37. Temperature management following cardiac arrest from non-shockable rhythm (PEA/Asystole)** - AHA 2023 update: Targeted Temperature Management (TTM) — avoid fever (>37.5°C) mandatory; TTM at 32-36°C for 24h — evidence evolving (TTM2 trial: no benefit of 33°C vs normothermia in unwitnessed arrest); fever avoidance universally recommended; ILCOR 2021 **Q38. Causes, diagnosis and management of venous air embolism under anaesthesia** - Causes: sitting position, open veins above heart level, Trendelenburg, laparoscopy (CO2), central line placement - Diagnosis: ETCO2 sudden drop, precordial Doppler (most sensitive), mill-wheel murmur, TEE - Management: Stop N2O, 100% O2, flood surgical field, left lateral decubitus + Trendelenburg (Durant manoeuvre), aspirate CVP catheter, CPR if arrest **Q39. Common complications after CABG (10 marks)** - Cardiovascular: low cardiac output syndrome (IABP, inotropes), arrhythmias (AF 20-40%, amiodarone), myocardial infarction, tamponade - Neurological: stroke (1-3%), cognitive dysfunction, peripheral neuropathy - Pulmonary: atelectasis, pleural effusion, ARDS, phrenic nerve palsy - Renal: AKI (post-CPB inflammatory response, contrast, low CO) - Haematological: coagulopathy, HIT - Sternal wound: mediastinitis, dehiscence - Vascular graft: early graft failure, graft spasm SEARCH INSTRUCTIONS: - SQL: SELECT title, book_title, '/textbooks/' || block_file_path AS file_path, line_number, para_line_ranges FROM headings_fts WHERE headings_fts MATCH 'cardiopulmonary bypass weaning' ORDER BY rank LIMIT 5 - Also: SELECT book_title, section_heading, '/textbooks/' || block_file_path AS file_path, line_start, line_end, snippet(paragraphs_fts, 0, '>>>', '<<<', '...', 30) as snippet FROM paragraphs_fts WHERE paragraphs_fts MATCH 'ventricular tachycardia amiodarone' ORDER BY rank LIMIT 5 - Read file content after getting paths using read_file - Cite specific textbooks (Miller's, Kaplan's, Morgan & Mikhail, Hensley's, Hines) - Provide detailed, structured exam answers with tables, drug doses, algorithms Return comprehensive answers for ALL questions listed above.

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1. CABG + Cardiopulmonary Bypass (CPB) CABG * Off-pump CABG (OPCAB) * Indications * Technique * Advantages & disadvantages * Common complications after CABG and management Cardiopulmonary Bypass * Heparin use during CPB * Cardioplegia * Weaning from CPB — prerequisites * Complications after CPB and management * Aortic cross-clamping * Hemodynamic changes * Metabolic changes * Therapeutic interventions ⸻ 2. ECMO * Extracorporeal membrane oxygenation (ECMO) * Role of ECMO in COVID ⸻ 3. Cardiac Arrest, CPR & Post-Resuscitation Care Cardiac Arrest Care * Post-cardiac arrest care * Temperature management after cardiac arrest (non-shockable rhythm) CPR * ACLS algorithm for ventricular fibrillation * Comprehensive Cardiopulmonary Life Support (CCLS) guidelines * Parameters of good-quality CPR * Differences between infant and adult CPR ⸻ 4. Arrhythmias & Electrical Therapy Ventricular Tachycardia / Ventricular Fibrillation * Management of ventricular tachycardia * ACLS for VF Atrial Fibrillation * Causes * Diagnosis * Treatment under anaesthesia Cardioversion * Indications * Technique * Precautions * Complications ⸻ 5. Pacemakers, ICD & Cardiac Devices * Classification of pacemakers and ICDs * Preoperative evaluation * Perioperative precautions * Anaesthetic considerations in patients with permanent pacemaker ⸻ 6. Myocardial Ischemia, Coronary Circulation & CAD Myocardial Ischemia * Diagnosis of myocardial ischemia under GA * Management under anaesthesia * Monitoring of ischemia during anaesthesia Coronary Circulation * Coronary circulation (diagram + description) * Regulation of coronary blood flow Myocardial Oxygen Balance * Factors affecting myocardial oxygen consumption * Clinical significance CAD Patients for Non-cardiac Surgery * CAD with drug-eluting stent for non-cardiac surgery * Preoperative assessment * Risk stratification * Anaesthetic plan Common surgeries asked: * Total knee replacement * Total hip replacement * Laparoscopic cholecystectomy ⸻ 7. Hypertension & Blood Pressure * Definition of blood pressure * Accurate BP measurement * Types of hypertension * Perioperative management of hypertensive patient ⸻ 8. Valvular Heart Disease — Mitral Stenosis Pathophysiology * Mitral stenosis pathophysiology Anaesthetic Management * Severe MS for: * LSCS * Emergency appendicectomy ⸻ 9. Cardiac Risk Assessment & Preoperative Evaluation High-risk/Frail Patients * Elderly smoker with hypertension * Frail elderly with CAD/diabetes * Diastolic dysfunction Topics commonly integrated * Functional capacity * Risk indices * Optimization * Medication management * Perioperative cardiac concerns * Metabolic concerns ⸻ 10. Cardiac Output Monitoring * Non-invasive cardiac output monitoring ⸻ 11. Ventricular Function & Hemodynamics Basic Hemodynamics * Preload * Afterload LV Diastolic Function * Determinants of LV diastolic function ⸻ 12. Transesophageal Echocardiography (TEE) * Role of TEE in cardiac anaesthesia ⸻ 13. Cardiopulmonary Exercise Testing (CPET) * Indications * Contraindications * Methods * Interpretation ⸻ 14. Venous Air Embolism (VAE) Causes * Venous air embolism * Arterial air embolism Pathophysiology * Paradoxical air embolism Diagnosis * Role of capnography Management * Treatment under anaesthesia ⸻ 15. Obstetric Cardiac Anaesthesia * Aortocaval compression * Severe mitral stenosis in pregnancy/LSCS ⸻ 16. Congenital Heart Disease * Cyanotic congenital heart disease * Acyanotic congenital heart disease ⸻ 17. IVC Ultrasound * Inferior vena cava collapsibility index Answer these question for dnb theory exam anaesthesia consise of possible pneumonic to learn and under subheadings from genuine source like miller stoeilting and latest guidelines if any

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You are a DNB Anaesthesia exam expert specializing in cardiac anaesthesia. Research the following topics from the medical library database. Use query_library_db with headings_fts and paragraphs_fts searches, then read file content with read_file. Cite Miller's Anaesthesia, Kaplan's Cardiac Anaesthesia, Morgan & Mikhail, Hensley's Practical Approach to Cardiac Anaesthesia, Stoelting's. TOPICS TO COVER (Part 2 — Pacemakers, Ischemia, Coronary Circulation, Hypertension, Valvular Disease, Risk Assessment, Non-invasive CO, TEE, CPET, Air Embolism, Obstetric, Congenital, IVC): **SECTION 5: PACEMAKERS AND ICDs** 1. **Classification of pacemakers and ICDs** - NBG/NASPE-BPEG 5-letter code: * Position I: Chamber paced (O=none, A=atrium, V=ventricle, D=dual) * Position II: Chamber sensed (O, A, V, D) * Position III: Response to sensing (O=none, I=inhibited, T=triggered, D=dual) * Position IV: Rate modulation (O=none, R=rate responsive) * Position V: Multisite pacing (O, A, V, D) - Common modes: VVI (pacemaker-dependent), DDD (physiological), VOO (asynchronous), AOO - ICD classification: HRS code — shock coil position, detection/therapy zones - CIED (Cardiac Implantable Electronic Device) terminology 2. **Preoperative evaluation of pacemaker/ICD patient** - KNOW: Why device implanted (indication — complete heart block, SSS, CHF resynchronisation) - Device details: manufacturer, model, year implanted, last interrogation date - Battery status (elective replacement indicator) - Pacemaker dependency: is patient pacemaker-dependent? (rate <40 without pacing) - Current settings: base rate, upper rate, pacing thresholds, sensing - ICD: is anti-tachycardia therapy (shock) active? When last shocked? - CXR: verify lead positions - Functional assessment: recent ECG showing capture 3. **Perioperative precautions and anaesthetic considerations for permanent pacemaker/ICD** - ELECTROSURGERY (diathermy): greatest risk — EMI can inhibit pacing or trigger ICD shock * BIPOLAR diathermy: preferred (minimal EMI); current stays between forcep tips * MONOPOLAR: use only if unavoidable; short bursts; keep return plate far from device; keep current path away from CIED * Keep monopolar current path >15 cm from pacemaker - MAGNET application: * Pacemaker: converts to asynchronous (AOO/VOO/DOO) at manufacturer-specific magnet rate — protects pacemaker-dependent patient from inhibition by EMI * ICD: SUSPENDS anti-tachycardia therapy (shocks) — DOES NOT change pacing mode * Should have external defibrillator immediately available if ICD inactivated - REPROGRAMMING: preferred for high-EMI procedures (laparoscopy, TURP); reprogram to VOO/AOO and disable ICD therapies via programmer; restore post-op - Monitoring: continuous ECG, pulse oximetry (verify mechanical pulse with each pacemaker spike) - Positioning: avoid stretching arm above head (can displace leads) - Avoid: succinylcholine fasciculations (may cause EMI-like signals); neostigmine (bradycardia in non-dependent patients) - MRI: MRI-conditional devices require specific protocols **SECTION 6: MYOCARDIAL ISCHEMIA, CORONARY CIRCULATION** 4. **Diagnosis and management of myocardial ischemia under GA** - DIAGNOSIS: * ECG: most practical — new ST depression >1mm (horizontal/downsloping), ST elevation (STEMI), new T-wave inversion, new LBBB; Monitor leads II (inferior) + V5 (anterior = most sensitive lead) * TEE: new RWMA (Regional Wall Motion Abnormality) — most sensitive (precedes ECG changes); appears before ST changes; wall motion score * PA catheter: new V wave on PCWP trace (MR from ischaemia), ↑ PCWP, ↓ CO * Clinical: new hypotension, tachycardia, ↑ CVP - MANAGEMENT (mnemonic: ABCDE or "FIX IT"): * Fix the rate: HR 60-80 bpm; beta-blocker (esmolol 0.5 mg/kg) or increase depth of anaesthesia * Fix preload: correct hypovolaemia (restore coronary perfusion pressure = DBP - LVEDP) * Fix afterload: if hypertensive → nitroglycerin (GTN) 0.5-5 mcg/kg/min (↓ preload, dilates coronaries) * Fix coronary perfusion: ensure DBP adequate (phenylephrine if DBP low) * Oxygen: increase FiO2; correct anaemia if Hb <8 * Consider: IABP if haemodynamically compromised; heparin; post-op cath lab * Notify surgeon: consider whether to proceed or abort 5. **Coronary circulation — diagram + description + regulation** - ANATOMY: * LCA (Left Coronary Artery): arises from left coronary sinus of Valsalva - LAD (Left Anterior Descending): supplies anterior LV wall, anterior septum, apex; diagonal branches - LCx (Left Circumflex): supplies lateral LV wall, posterior LV (left dominant); obtuse marginal branches * RCA (Right Coronary Artery): arises from right coronary sinus; supplies right ventricle, inferior LV (right dominant), SA node (55%), AV node (90%) - DOMINANCE: Right dominant (85%) = RCA gives PDA; Left dominant (10%); Co-dominant (5%) - PERFUSION TIMING: LV perfuses during DIASTOLE (systole compresses intramyocardial vessels); RV perfuses during both systole and diastole - CORONARY PERFUSION PRESSURE (CPP) = DBP − LVEDP (target DBP >60 mmHg perioperatively) - REGULATION: Autoregulation maintains CBF constant at MAP 60-160 mmHg * Metabolic: adenosine (most important vasodilator), CO2, O2, K+, H+ * Myogenic: pressure-flow autoregulation * Neurogenic: alpha-adrenergic (vasoconstriction), beta-2 (vasodilation) * Endothelial: NO (vasodilation), endothelin (vasoconstriction) - In anaemia/hypotension: autoregulation fails → supply-demand mismatch 6. **Factors affecting myocardial O2 consumption (MVO2)** - DETERMINANTS (mnemonic: THRC = Three HR Components): * HEART RATE: MOST IMPORTANT determinant (doubles MVO2 when HR doubles); also reduces diastolic filling time → ↓ perfusion * WALL TENSION (Laplace's law = P×r/2h): determined by PRELOAD (EDV) + AFTERLOAD (SVR) * CONTRACTILITY (inotropy): ↑ contractility → ↑ MVO2 * Basal metabolism (~20% MVO2): irreducible minimum for cell viability - O2 SUPPLY factors: coronary flow, Hb, SpO2, CPP - SUPPLY:DEMAND RATIO determines ischaemia - Clinical significance: * Tachycardia: most dangerous (↑ demand + ↓ supply) → beta-blockers * Hypertension: ↑ afterload → ↑ MVO2 → treat perioperative hypertension * Anaemia: ↓ supply → transfuse if Hb <8 in CAD * Nitrates: ↓ preload + coronary dilation → reduce MVO2 7. **CAD with drug-eluting stent — preoperative assessment + anaesthetic plan** - ANTIPLATELET THERAPY (DAPT): * BMS (bare metal stent): defer elective surgery ≥4-6 weeks minimum; ideally 3 months * DES (drug-eluting stent): defer elective surgery ≥6 months (old DES) to ≥12 months ideally; ≥3 months if surgery cannot be delayed (ACC/AHA 2022 guidelines) * If surgery urgent: CONTINUE BOTH aspirin + P2Y12 if stent <3 months; consult cardiology * At ≥12 months: Stop clopidogrel 5-7 days before; CONTINUE ASPIRIN throughout perioperatively * NO heparin bridging for antiplatelet therapy (increases bleeding without reducing stent thrombosis) - PERIOPERATIVE BETA-BLOCKER: continue (do NOT abruptly stop — rebound ischaemia) - ACE-i/ARB: hold on morning of surgery (hypotension risk); restart 24h post-op - Statins: CONTINUE perioperatively (pleiotropic effects, plaque stabilisation) - Monitoring: ECG lead II + V5, arterial line; consider TEE in high-risk - Regional vs GA: neuraxial/regional has cardiac benefits (↓ stress response, ↓ DVT); epidural for TKR/THR - Timing of neuraxial after stopping antiplatelet: clopidogrel 7 days, ticagrelor 5 days, prasugrel 7 days **SECTION 7: HYPERTENSION** 8. **Blood pressure — definition, accurate measurement, types** - DEFINITION: Arterial blood pressure = cardiac output × systemic vascular resistance - Normal: SBP <120, DBP <80 mmHg - ACCURATE MEASUREMENT: * Patient preparation: seated quietly 5 min, no caffeine/exercise for 30 min, empty bladder * Cuff size: width = 40% of arm circumference; length = 80% of arm circumference; wrong cuff = false reading * Auscultatory method: Korotkoff sounds: K1 = SBP, K5 = DBP (K4 in special cases) * At least 2 readings, 1-2 min apart; average used * Both arms initially; use higher reading arm * Orthostatic measurements if indicated - TYPES: * Essential (primary) hypertension: 90-95%; no identifiable cause * Secondary hypertension: 5-10%: renal (renovascular, parenchymal), endocrine (phaeochromocytoma, Conn's, Cushing's, hyperthyroidism), coarctation, OSA, drugs * White coat hypertension: elevated in clinic; normal on ABPM * Masked hypertension: normal in clinic; elevated on ABPM * Resistant hypertension: uncontrolled despite 3 drugs (including diuretic) * Hypertensive urgency: severe BP (>180/120) without end-organ damage * Hypertensive emergency: severe BP with end-organ damage (encephalopathy, STEMI, aortic dissection, AKI) - JNC 8 / ACC/AHA 2017 classification: Normal <120/80; Elevated 120-129/<80; Stage 1: 130-139/80-89; Stage 2: ≥140/≥90 - Perioperative: elective surgery if DBP >110 mmHg — postpone and optimise; SBP >180/DBP >110 = postpone **SECTION 8: VALVULAR HEART DISEASE — MITRAL STENOSIS** 9. **Pathophysiology of mitral stenosis** - Cause: Rheumatic fever (90%); calcification (elderly) - Normal MVA = 4-6 cm²; Mild MS >1.5 cm²; Moderate 1.0-1.5 cm²; Severe <1.0 cm² - Critical <0.6 cm² - HAEMODYNAMIC CASCADE: * ↑ mitral valve gradient → ↑ LAP → LA dilatation → AF (50%) → pulmonary venous hypertension → pulmonary arterial hypertension → RV failure → tricuspid regurgitation → right heart failure * Fixed cardiac output (CO depends on diastolic filling time) * Tachycardia: ↓ diastolic filling time → ↓ CO → ↑ LAP → flash pulmonary oedema - Gorlin formula: valve area = flow / (constant × √ mean gradient) - Haemodynamic goals: HR 60-80 (avoid tachycardia), NSR (maintain if possible), avoid ↑ pulmonary resistance (avoid hypoxia, hypercarbia, acidosis), adequate preload but avoid fluid overload 10. **Anaesthetic management of severe MS for LSCS** - Pre-op: optimize (diuretics, beta-blocker for rate control, digoxin/amiodarone if AF), assess functional class, echo for MVA and PAP - MODE OF ANAESTHESIA: Regional preferred (spinal carries risk of sudden hypotension — use low-dose/slow epidural preferred) - EPIDURAL: drug of choice — incremental dosing, slow onset, haemodynamically predictable - SPINAL: use with extreme caution; low-dose spinal + epidural (CSE with very low spinal dose) - Avoid: tachycardia (ketamine increases HR — avoid), aortocaval compression (left lateral tilt) - Vasopressors: PHENYLEPHRINE (pure alpha — maintains SVR without ↑ HR) preferred over ephedrine (which causes tachycardia) - INTRAOPERATIVE goals: HR 60-80, maintain sinus rhythm, adequate SVR, avoid pulmonary vasoconstrictors - OXYTOCIN: give SLOWLY (10 units over 15-20 min); rapid bolus → ↓ SVR → ↑ HR → flash pulmonary oedema; avoid ergometrine (causes coronary/pulmonary vasoconstriction, ↑ SVR) - Post-op: ICU monitoring; beware of fluid shifts 11. **Anaesthetic management of severe MS for emergency appendicectomy** - Emergency: cannot delay; optimise as far as possible in limited time - Pre-op: IV beta-blocker (esmolol/metoprolol) to control rate; diuretics if pulmonary congestion - ANAESTHESIA CHOICE: * Regional (spinal ± epidural) if coagulation normal, haemodynamics allow — avoids GA risks * GA if regional contraindicated: use ETOMIDATE (haemodynamically stable induction), avoid ketamine (↑ HR), careful opioid use - RSI considerations: modified RSI (avoid succinylcholine if K+ concerns); rocuronium + sugammadex - Maintain: HR <80, avoid hypotension, avoid ↑ pulmonary resistance - Vasopressors: phenylephrine - Monitoring: invasive arterial line, consider CVP - Post-op: HDU/ICU **SECTION 9: CARDIAC RISK ASSESSMENT** 12. **Risk assessment for IHD patient for non-cardiac surgery (Revised Cardiac Risk Index — RCRI)** - LEE'S RCRI (1999) — 6 independent predictors: 1. High-risk surgery (suprainguinal vascular, intrathoracic, intraperitoneal) 2. History of ischemic heart disease 3. History of congestive heart failure 4. History of cerebrovascular disease 5. Insulin-dependent diabetes 6. Preoperative serum creatinine >2.0 mg/dL - RISK: Score 0 = 0.4%, Score 1 = 1%, Score 2 = 2.4%, Score 3+ = 5.4% major cardiac event - ACC/AHA STEPWISE ALGORITHM: 1. Emergency? → No time for evaluation, proceed with monitoring 2. Active cardiac conditions? (ACS, decompensated HF, severe valvular disease, significant arrhythmia) → stabilise first 3. Low-risk surgery? (MACE risk <1%: superficial, endoscopic, cataract, breast) → proceed 4. Functional capacity ≥4 METs? → can proceed without further testing (climb 2 flights, walk on level ground at 4mph) 5. Clinical risk factors: use RCRI; if ≥3 factors + high-risk surgery → consider stress testing/optimisation 13. **Frail elderly with diastolic dysfunction — perioperative concerns** - Diastolic dysfunction grades (ACC/AHA echocardiographic criteria) - Implications: stiff LV, filling pressure-dependent, sensitive to tachycardia, preload, afterload - Haemodynamic goals: maintain sinus rhythm, HR 60-70, adequate preload (Starling), avoid tachycardia and SVT - Drugs: spironolactone, ACE-i/ARB for structural reverse remodelling - Perioperative: avoid fluid overload AND fluid deficit; invasive monitoring (arterial line); CVP/TEE-guided **SECTION 10: NON-INVASIVE CARDIAC OUTPUT MONITORING** 14. **Non-invasive cardiac output monitoring methods** - THORACIC BIOIMPEDANCE (TBI): measures ΔZ (change in electrical impedance of thorax with cardiac cycle); CO = formula using ΔZ, weight, height, HR; affected by oedema, pleural effusion - BIOREACTANCE (NICOM): measures phase shifts in current; less affected by tissue fluid than bioimpedance; validated in critical care - OESOPHAGEAL DOPPLER (ODM — CardioQ): semi-invasive probe; measures descending aortic flow velocity; Doppler waveform = stroke volume, corrected flow time (FTc); real-time fluid responsiveness; validated for goal-directed fluid therapy in surgical patients - PULSE CONTOUR ANALYSIS (Flotrac/Vigileo, PiCCO): analyses arterial waveform morphology for CO; requires arterial line (minimally invasive); continuous CO; Flotrac = uncalibrated; PiCCO requires calibration (TPTD) - USCOM (Ultrasonic Cardiac Output Monitor): transcutaneous Doppler; suprasternal notch probe - NICO (non-invasive CO): partial CO2 rebreathing method (Fick principle with CO2); requires intubation; not truly non-invasive - PLETHYSMOGRAPHY VARIABILITY INDEX (PVI): pulse oximeter-derived; respiratory variation in plethysmographic waveform; fluid responsiveness indicator - PPV (Pulse Pressure Variation): arterial line + mechanical ventilation; >13% = fluid responsive **SECTION 11: TEE** 15. **Role of TEE in cardiac anaesthesia** - INDICATIONS (ASE/SCA Guidelines): Category A (supported by evidence): valve surgery, congenital heart surgery, LVAD insertion, pericardial surgery, aortic surgery, endocarditis complications Intraoperative haemodynamic instability unexplained by clinical data - KEY INFORMATION FROM TEE: * Ventricular function: LV/RV systolic and diastolic function, EF (Simpson's biplane), RWMA * Valvular: severity of regurgitation/stenosis, vegetations, repair assessment post-bypass * Aorta: atheroma, dissection, aneurysm * Intracardiac: thrombus (LAA), air embolism detection, ASD/VSD/PFO * Haemodynamics: filling pressures (estimated), tamponade (RA/RV collapse) * Post-bypass: assess adequacy of repair, residual lesions, new RWMA - VIEWS: 5 standard windows: transgastric (mid-papillary SAX best for circumferential LV function), mid-oesophageal (4-chamber, 2-chamber, LAX), deep transgastric (LVOT), upper oesophageal (aortic arch) - CONTRAINDICATIONS: oesophageal stricture/cancer/varices, recent oesophageal surgery, active GI bleed - ADVANTAGES over TTE: superior image quality in intubated/obese patients; continuous monitoring **SECTION 12: CPET** 16. **Perioperative cardiopulmonary exercise testing (CPET)** - PRINCIPLE: Integrated response of cardiac, pulmonary, and muscular systems to incremental exercise - KEY PARAMETERS: * VO2 max (peak O2 consumption): <15 mL/kg/min = high risk; >20 = low risk * Anaerobic Threshold (AT/VT1): O2 uptake at which anaerobic metabolism begins; <11 mL/kg/min = high risk for major surgery; >11 = intermediate; >14 = low risk * VE/VCO2 slope: >35 = high risk (poor ventilatory efficiency; reflects pulmonary HTN, HF) * O2 pulse (VO2/HR): surrogate for stroke volume; flat response = cardiac limitation - INDICATIONS: pre-op assessment for: major abdominal surgery (oesophagectomy, hepatic resection), thoracic surgery, TAVI pre-assessment, cardiac transplant listing, lung transplant assessment - CONTRAINDICATIONS: unstable angina, recent MI (<1 month), uncontrolled HF, severe AS, uncontrolled arrhythmia, severe HTN (SBP >200), unable to exercise - PROTOCOL: Ramp cycle ergometry; continuous 12-lead ECG, breath-by-breath spirometry - ALTERNATIVE: 6-minute walk test (<350m = poor functional capacity), Duke Activity Status Index (DASI) **SECTION 13: VENOUS AIR EMBOLISM** 17. **VAE — Causes, pathophysiology, paradoxical air embolism, capnography, management** - CAUSES: * Venous: sitting craniotomy (most common neurosurgical), open cardiac surgery, central line insertion/removal, hip arthroplasty, liver transplant, laparoscopy (CO2 though), C-section, laser hysteroscopy, any open vein above heart level * Arterial air embolism: iatrogenic (arterial line, cardiac surgery), paradoxical via PFO - DETECTION SENSITIVITY ORDER (most → least sensitive): 1. TOE (TEE): detects 0.02 mL/kg 2. Precordial Doppler: detects 0.25 mL; hissing/roaring sound; standard of care 3. Pulmonary artery pressure: rises 4. ETCO2: SUDDEN ↓ (↑ dead space) — practical, continuous, already on all patients 5. CVP: rises 6. BP/ECG/mill-wheel murmur: very late signs - PATHOPHYSIOLOGY: air in RV → air lock → obstruction of RVOT → ↓ CO; air reaches pulmonary vessels → ↑ PVR; massive air → cardiac arrest - PARADOXICAL AIR EMBOLISM: air crosses from right to left heart via PFO (present in 25% of adults) or ASD → systemic circulation → stroke, coronary occlusion, end-organ ischaemia; occurs when RAP > LAP (large VAE event, PEEP) - CAPNOGRAPHY in VAE: air in pulmonary vasculature → ↑ physiological dead space (no perfusion) → ↓ ETCO2; ETCO2 drop precedes haemodynamic compromise; gradient between ETCO2 and PaCO2 widens - MANAGEMENT: 1. Notify surgeon; FLOOD FIELD with saline; pack wound; bone wax on skull edges 2. Bilateral jugular venous compression 3. Discontinue N2O → FiO2 1.0 (N2O expands air bubbles) 4. Lower surgical site / head down (if possible) 5. Aspirate right heart catheter (multiorificed tip at SVC-RA junction) 6. Vasopressors + volume loading 7. NO PEEP (increases PAE risk via PFO) 8. Durant's manoeuvre: left lateral decubitus + Trendelenburg → moves air away from RVOT 9. CPR if arrest; hyperbaric oxygen for neurological injury **SECTION 14: OBSTETRIC CARDIAC** 18. **Aortocaval compression** - Mechanism: gravid uterus ≥20 weeks compresses IVC (80-90% reduction in venous return) and aorta in supine position - Results: ↓ venous return → ↓ preload → ↓ CO → hypotension (supine hypotension syndrome in 10% symptomatic, 80% subclinical) - PREVENTION: Left lateral uterine displacement (LUD) 15-30° (wedge under right hip) - Manual LUD by assistant during CPR in pregnancy - Significance in spinal anaesthesia for CS: pre-loading + LUD + phenylephrine infusion 19. **Severe MS in pregnancy for LSCS** — (covered in Section 8 above — refer to Q10) **SECTION 15: CONGENITAL HEART DISEASE** 20. **Cyanotic and acyanotic congenital heart disease** - ACYANOTIC (L→R shunts initially, no cyanosis): * VSD (most common CHD overall — 32%): pansystolic murmur; Eisenmenger if large * ASD (most common in adults): fixed split S2; types: ostium secundum (70%), primum (30%), sinus venosus * PDA: continuous machinery murmur; treat with indomethacin (preterm) or surgical ligation * Coarctation of aorta: upper limb hypertension, weak femoral pulses, rib notching on CXR * Pulmonary stenosis: ejection systolic murmur, right ventricular hypertrophy * Aortic stenosis (congenital bicuspid valve) - CYANOTIC (R→L shunts, cyanosis from birth or early): * TOF (most common cyanotic CHD): 4 components = VSD + RVOTO + overriding aorta + RVH; tet spells (hypercyanotic); squat to ↑ SVR; treat spell with O2 + knee-chest + phenylephrine + beta-blocker * TGA (D-TGA): aorta arises from RV, PA from LV; parallel circuits; needs mixing (ASD/PDA/VSD) for survival; balloon atrial septostomy at birth; arterial switch operation * Tricuspid atresia: absent TV; single ventricle physiology; Fontan procedure * TAPVD (Total anomalous pulmonary venous drainage): all PVs drain to right heart; requires mixing at ASD * Truncus arteriosus: single great artery giving rise to aorta + PA; early Eisenmenger risk * Ebstein anomaly: displaced tricuspid valve (atrialized RV); WPW association; TR, cyanosis - Eisenmenger syndrome: reversal of shunt (L→R → R→L) due to pulmonary hypertension **SECTION 16: IVC COLLAPSIBILITY INDEX** 21. **IVC collapsibility index** - MEASUREMENT: M-mode or 2D ultrasound; subcostal window; measure IVC 2 cm from RA junction - FORMULA: IVC-CI = (IVCmax - IVCmin) / IVCmax × 100% - Where: IVCmax = diameter at end-expiration; IVCmin = diameter at peak inspiration (sniff test) - INTERPRETATION (spontaneously breathing patients): * IVC-CI >50%: low RAP (<8 mmHg) → likely fluid responsive * IVC-CI <50%: higher RAP → less likely fluid responsive - DISTENSIBILITY INDEX (mechanically ventilated): (IVCmax - IVCmin) / IVCmin >18% = fluid responsive - NORMAL IVC diameter: 1.5-2.5 cm (adults) - LIMITATIONS: * Spontaneous breathing vs mechanical ventilation (different thresholds) * Tricuspid regurgitation: IVC plethoric regardless of volume status * RV failure: dilated IVC despite adequate filling * Raised intraabdominal pressure (obese, pregnancy, ascites): IVC compressed → false high collapsibility * Operator-dependent; poor acoustic window in obese patients * Open chest surgery: IVC pressure changes unreliable - CLINICAL USE: Volume responsiveness assessment, guide fluid therapy in ICU/ED/OT SEARCH INSTRUCTIONS: - SQL: SELECT title, book_title, '/textbooks/' || block_file_path AS file_path, line_number, para_line_ranges FROM headings_fts WHERE headings_fts MATCH 'transesophageal echocardiography cardiac surgery' ORDER BY rank LIMIT 5 - Also use paragraphs_fts for specific facts - Read actual file content - Provide clear subheadings, tables, mnemonics - Include drug doses throughout Return comprehensive, well-structured answers for ALL topics suitable for DNB theory exam cardiac anaesthesia.

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