Comprehensive Review: Anesthesiology & Critical Care - Recent Updates 2020-2026

For MD Final Anesthesia Examinations

SECTION 1: AIRWAY MANAGEMENT - MAJOR UPDATES

1.1 Difficult Airway Society (DAS) 2025 Guidelines - Unanticipated Difficult Intubation in Adults

• Three-attempt maximum for tracheal intubation before declaring failed intubation (unchanged)
• New emphasis on high-flow nasal oxygen (HFNO/THRIVE) during all attempts - maintains apnoeic oxygenation
• Video laryngoscopy (VL) as first-line for anticipated AND unanticipated difficult airways in many centres
• Supraglottic airway (SGA) as "Plan B" - second-generation SGAs (i-gel, ProSeal LMA) preferred
• "Can't Intubate Can't Oxygenate" (CICO) emergency: front-of-neck airway (FONA) - scalpel-bougie-tube technique is the recommended emergency surgical airway
• Abandoned "can't intubate can't ventilate" terminology; replaced by CICO

1.2 Awake Tracheal Intubation (ATI) - DAS Guidelines 2020

• NODESAT technique (Nasal oxygen during efforts securing the airway)
• Dexmedetomidine + remifentanil TCI are preferred sedation regimens for ATI
• Topical anaesthesia: lidocaine (max 9 mg/kg) via MAD, spray-as-you-go, cricothyroid injection
• Videolaryngoscope-guided ATI as alternative to fibreoptic intubation
• Absolute indications for ATI: known difficult airway, full stomach + difficult airway, severe cervical instability

1.3 COVID-19 Airway Guidelines (DAS/ICS/RCoA 2020)

• PPE before airway management (FFP3/N95 mask, eye protection, gown, gloves)
• Modified RSI: rocuronium 1.2 mg/kg preferred; ketamine or etomidate for induction
• Video laryngoscope as first-line to reduce proximity exposure
• Avoid bag-mask ventilation if possible; if needed use HEPA filter

Q: What is the DAS 2025 recommendation for front-of-neck airway? A: Scalpel-bougie-tube technique (surgical CICO): horizontal stab incision through skin + cricothyroid membrane, 10-blade scalpel, introducer (bougie), 6.0 cuffed ETT. Cannula CICO (4mm) is an alternative if surgical approach fails.

Q: What is the role of HFNO/THRIVE in difficult airway? A: High-Flow Nasal Oxygen (15 L/min via nasal prongs during laryngoscopy) exploits apnoeic oxygenation and gaseous diffusion to extend safe apnoea time from ~3 min to >10 min. The THRIVE study showed median apnoea time of 17 min.

Q: When is video laryngoscopy preferred over direct laryngoscopy? A: (1) Known or predicted difficult airway, (2) Limited mouth opening, (3) Cervical immobility, (4) Blood/secretions in airway (hyperangulated blade preferred), (5) Teaching/training. VL does NOT abolish the need for DL skills.

SECTION 2: PHARMACOLOGY - NEW DRUGS AND UPDATES

2.1 REMIMAZOLAM - The Newest Benzodiazepine

• Induction dose: 6-12 mg/bolus; sedation: 0.2-0.4 mg/kg/hr infusion
• Onset: 1-3 min; Duration: 5-10 min
• Reversible with flumazenil (unlike propofol)
• Cardiovascular stability: less hypotension than propofol; no pain on injection
• No propofol infusion syndrome risk
• Less respiratory depression than propofol
• Approved by FDA (2020) for procedural sedation; Japan (2020) for general anaesthesia

• Less intraoperative hypotension ✓
• Less injection pain ✓
• Similar induction time
• More reliable sedation than midazolam
• Faster recovery than midazolam

Q: What makes remimazolam unique among benzodiazepines? A: It undergoes organ-independent ester hydrolysis by tissue esterases to an inactive metabolite. This gives it a predictable ultra-short duration regardless of hepatic/renal function - unlike midazolam (hepatic oxidation) or diazepam (hepatic). It is also the only benzodiazepine with flumazenil reversibility + ester metabolism combination. Safe in hepatic/renal failure.

Q: Compare remimazolam and propofol for procedural sedation. A: Remimazolam advantages: (1) No injection pain (propofol burns), (2) Less hypotension (cardiovascular stability), (3) Reversible with flumazenil, (4) No PRIS risk, (5) Safe in egg/soy allergy, (6) Better for fragile patients. Propofol advantages: (1) Better antiemetic properties, (2) Faster onset, (3) More studied globally, (4) Cheaper.

2.2 TARGET CONTROLLED INFUSION (TCI) - Updates

• Propofol: Schneider model (plasma-controlled: Cp) or Marsh model (effect site: Ce)
  • Schneider: accounts for age, height, weight, gender - preferred in elderly
  • Effect-site targeting: Ce, which accounts for blood-brain equilibration (ke0)
• Remifentanil: Minto model
• Dexmedetomidine: Hannivoort-Colin model (now included in clinical TCI pumps)
• Ketamine: Domino model

• Cp = plasma concentration target; Ce = effect-site concentration target
• Ke0 = rate constant for plasma-effect site equilibration
• Context-sensitive half-time: propofol rises significantly after >8 hours infusion (vs remifentanil which stays ~3-4 min regardless of infusion duration)
• TIVA mandatory: sinus/middle ear surgery, malignant hyperthermia risk, airway surgery, operations with inhalation agent delivery compromised

Q: What is ke0 and why does it matter in TCI? A: ke0 is the first-order rate constant describing movement of drug from plasma to effect site. A larger ke0 = faster plasma-effect site equilibration = shorter lag time between plasma peak and clinical effect. For propofol: ke0 ~0.26 min⁻¹ with ~3-5 min lag. Effect-site targeting automatically overshoots plasma concentration briefly to drive drug into CNS faster, allowing earlier peak effect.

Q: What is context-sensitive half-time? Why does it matter for remifentanil vs fentanyl? A: Context-sensitive half-time is the time for the plasma concentration to fall 50% after stopping an infusion, as a function of the duration of infusion ("context" = infusion duration). Remifentanil: ~3-4 min regardless of infusion length (ester hydrolysis, no accumulation). Fentanyl: rises from ~20 min (1h infusion) to >200 min (8h infusion) due to redistribution from fat. This is why remifentanil is ideal for infusions of any duration.

2.3 GLP-1 RECEPTOR AGONISTS - NEW PERIOPERATIVE CONCERN (2023-2026)

• Daily dosing: hold 1 day before elective surgery
• Weekly dosing (semaglutide/dulaglutide): hold 1 week before elective surgery

• Treat as full stomach protocol
• Use rapid sequence induction (RSI)
• Gastric ultrasound (POCUS) to assess gastric content

Q: A patient on weekly semaglutide presents for elective laparoscopy. How do you manage? A: (1) Check if semaglutide held for 7 days - if yes and standard fasting met, proceed with standard precautions; (2) If NOT held or uncertainty, perform gastric POCUS - cross-sectional area (CSA) >340 mm² in right lateral decubitus = significant gastric content = high risk; (3) If high risk: proceed as full stomach - RSI with cricoid pressure, ketamine/propofol + suxamethonium 1.5 mg/kg or rocuronium 1.2 mg/kg + sugammadex reversal available.

SECTION 3: NEUROMUSCULAR BLOCKADE - CURRENT PRACTICE

3.1 Sugammadex - Key Facts (Morgan & Mikhail 7e; Miller's 10e)

• Deep block (PTC 1-2): 16 mg/kg
• Moderate block (TOF count 1-2): 4 mg/kg
• Shallow block (TOF ratio 0.4-0.9): 2 mg/kg
• Rocuronium-induced CICO emergency reversal: 16 mg/kg immediately

• Rocuronium cannot be re-used for 24 hours (complex remains in circulation)
• Can use succinylcholine for re-intubation within 24 hours
• Or use non-steroidal NMBA (cisatracurium)

• TOF ratio <0.9 = residual paralysis. Clinically: patient may feel unable to swallow, pharyngeal dysfunction, hypoxia
• Neostigmine ceiling effect: only works at TOF count ≥2; incomplete at deep block
• Sugammadex superior to neostigmine (no ceiling effect, faster, no muscarinic side effects)

Q: What is the dose of sugammadex for emergency reversal of rocuronium in CICO? A: 16 mg/kg IV immediately. This will fully reverse even 1.2 mg/kg rocuronium within ~3 minutes. This is a rescue strategy when rocuronium was used for RSI and the airway cannot be secured and cannot be oxygenated. Keep 200 mg (or 400 mg in larger patients) readily available whenever rocuronium is used for RSI.

Q: What is quantitative neuromuscular monitoring? Why is it the standard of care? A: Quantitative monitoring measures TOF ratio numerically (acceleromyography, kinemyography). The standard of care is TOF ratio ≥0.9 (ideally ≥0.95) before extubation. Clinical tests (head lift 5 seconds, grip strength) can be met with TOF ratio as low as 0.6, making them unreliable for detecting PORC. Qualitative assessment (visual/tactile TOF) cannot reliably detect ratios between 0.4-0.9.

SECTION 4: ENHANCED RECOVERY AFTER SURGERY (ERAS)

4.1 Core ERAS Elements (2020-2024 Updates)

• Carbohydrate loading: up to 400 mL carbohydrate drink 2-3 hours before surgery (not just clear fluids)
• Prehabilitation: exercise, nutrition, smoking cessation, alcohol reduction ≥4 weeks before
• Preoperative anaemia correction (IV iron if Hb <100 g/L, elective surgery)
• Avoid routine bowel preparation (not shown to reduce complications)
• Multimodal premedication: paracetamol 1 g + celecoxib/gabapentin (evidence-based)

• Goal-directed fluid therapy (GDFT) using cardiac output monitoring
• Restrictive fluid management: avoid salt and water overload
• Maintenance of normothermia: forced-air warming, warmed IV fluids; target core temp >36°C
• Multimodal analgesia: regional blocks + paracetamol + NSAID + dexamethasone (reduces PONV and pain)
• Minimise opioids (opioid-free or opioid-sparing anesthesia)
• PONV prophylaxis: Apfel score ≥2 = dual therapy; ≥3 = triple therapy (ondansetron + dexamethasone + scopolamine/haloperidol)
• Short-acting agents preferred (desflurane/sevoflurane or TIVA)

• Early feeding (within 4-6 hours)
• Early mobilisation (same day)
• Avoid routine drains/nasogastric tubes
• Multimodal oral analgesia; minimise opioids
• Thromboprophylaxis: LMWH + compression stockings

Q: What is the evidence-based fasting guideline for solids and clear fluids before elective surgery? A: ASA/ESAIC guidelines: (1) Clear fluids up to 2 hours before induction; (2) Breast milk up to 4 hours; (3) Light meal (toast, no fat/meat) up to 6 hours; (4) Heavy/fatty meal up to 8 hours. Carbohydrate loading drinks (12.5% maltodextrin) allowed until 2 hours - reduces insulin resistance, nausea, and preserves lean body mass. Exception: emergency surgery, full stomach, gastroparesis, GLP-1 users (as above).

Q: What is the Apfel score and how does it guide PONV prophylaxis? A: Apfel score = 1 point each for: Female sex, Non-smoker, History of PONV/motion sickness, Postoperative opioid use. Score 0-1: low risk (no prophylaxis or single agent); Score 2: moderate risk (dual therapy - ondansetron 4mg + dexamethasone 8mg); Score 3-4: high risk (triple therapy + consider TIVA + regional anaesthesia to avoid volatile agents and opioids).

SECTION 5: OBSTETRIC ANESTHESIA - KEY UPDATES

5.1 Spinal Hypotension Management (Multiple meta-analyses 2020-2025)

• Norepinephrine (noradrenaline) 5-10 mcg bolus/infusion = first-line vasopressor (superior to phenylephrine)
  • Maintains uteroplacental blood flow better than phenylephrine
  • Less bradycardia than phenylephrine (phenylephrine causes reflex bradycardia via baroreceptors)
  • Higher cardiac output than phenylephrine
• Phenylephrine: still acceptable but causes more bradycardia, lower CO
• Ephedrine: use only when bradycardia is present; crosses placenta more, potential fetal acidosis
• Combined spinal-epidural (CSE) with intrathecal opioids for labour analgesia is standard

Q: Norepinephrine vs phenylephrine for spinal hypotension in C-section - what does the evidence show? A: Network meta-analyses (2023-2025) show norepinephrine superior: (1) Maintains higher maternal cardiac output (alpha+beta activity vs pure alpha of phenylephrine), (2) Less bradycardia, (3) Similar or better neonatal outcomes, (4) 50-100 mcg boluses or 0.05-0.1 mcg/kg/min infusion. Phenylephrine (100 mcg bolus) remains acceptable but causes reflex bradycardia in ~30% and reduces cardiac output.

Q: How do you manage high spinal block during caesarean section? A: (1) Call for help; (2) Left lateral tilt 15° (aortocaval decompression); (3) 100% O2 by face mask; (4) IV fluid bolus; (5) Vasopressor - norepinephrine/ephedrine (if HR <60, use ephedrine not phenylephrine); (6) If respiratory distress: assist ventilation; (7) If apnoea/unconscious: RSI + intubation; (8) Continue surgery if fetus at risk; (9) Block above T2 = intubate; watch for Horner syndrome (T1).

SECTION 6: CRITICAL CARE - MAJOR UPDATES

6.1 NEW GLOBAL ARDS DEFINITION 2023

• ARDS can now be diagnosed in non-intubated patients (HFNO/NIV) - enables earlier intervention
• LUS (lung ultrasound) replaces CXR in resource-limited settings
• SpO2/FiO2 ratio can substitute PaO2/FiO2 in non-intubated (SpO2/FiO2 <315 = ARDS equivalent of PF <300)

• Mild: PF 201-300 (on PEEP ≥5)
• Moderate: PF 101-200
• Severe: PF ≤100

6.2 Lung-Protective Ventilation - Current Evidence

• Tidal volume: 6 mL/kg IBW (not actual body weight)
• Plateau pressure ≤30 cmH2O
• Driving pressure ≤15 cmH2O (Driving pressure = Pplat - PEEP; strongest predictor of ARDS mortality)
• PEEP titration: ARDSnet low-PEEP table vs higher PEEP (controversial; higher PEEP recommended in moderate-severe ARDS)
• Prone positioning ≥16 hours/day for moderate-severe ARDS (PF <150): reduces mortality by ~16% (PROSEVA trial)
• Permissive hypercapnia: pH >7.2 acceptable
• Neuromuscular blockade (cisatracurium infusion) for first 48h in PF <150: ACURASYS trial (benefit); ROSE trial (no benefit) - current practice: early NMBA for patient-ventilator dyssynchrony

Q: What is driving pressure and why is it the key determinant in ARDS? A: Driving pressure (ΔP) = Plateau pressure - Total PEEP. It represents the actual stress applied to the lung parenchyma per breath. Amato et al. (NEJM 2015) showed ΔP >15 cmH2O was independently associated with mortality even when tidal volume and plateau pressure were within limits. ΔP is essentially the tidal volume normalised to respiratory system compliance - it reflects lung strain regardless of PEEP level.

Q: What is the role of ECMO in ARDS? What does the evidence say? A: VV-ECMO is indicated for severe ARDS (PF <80) refractory to conventional therapy including prone positioning. CESAR trial (2009): VV-ECMO centre referral reduced death. EOLIA trial (2018): did not show mortality benefit vs conventional (42% vs 33%) but 28% of control patients crossed over to ECMO as rescue. Meta-analysis (PMID 33021684, 2020): individual patient data analysis supports ECMO for PF <80 with reversible cause. ESICM 2023 guidelines: VV-ECMO recommended for selected severe ARDS patients in experienced centres.

6.3 Surviving Sepsis Campaign 2021 Updates

1. Measure lactate; re-measure if >2 mmol/L
2. Blood cultures before antibiotics (≥2 sets)
3. Administer broad-spectrum antibiotics within 1 hour of recognition
4. IV crystalloid 30 mL/kg for hypotension or lactate ≥4 mmol/L
5. Vasopressors if hypotensive during/after fluid resuscitation

• Norepinephrine = first-line vasopressor (target MAP 65 mmHg)
• Vasopressin as second-line (0.03 units/min); add early rather than increasing noradrenaline
• Hydrocortisone 200 mg/day IV if noradrenaline ≥0.25 mcg/kg/min after adequate fluid resuscitation
• IV vitamin C (Ascorbic acid): NOT recommended routinely (CITRIS-ALI and VITAMINS trials negative)
• Thiamine supplementation in thiamine-deficient patients (ICU patients at risk)
• Balanced crystalloids (Lactated Ringer's, PlasmaLyte) preferred over 0.9% NaCl (less hyperchloraemic acidosis, less AKI)
• IV albumin 4-5% for patients requiring substantial amounts of crystalloids
• Target glucose 140-180 mg/dL (moderate control); avoid tight control (hypoglycaemia risk)
• Prone positioning in moderate-severe ARDS from sepsis
• Early enteral nutrition within 72 hours; avoid parenteral unless GI failure
• SOFA score (not SIRS) defines organ dysfunction in Sepsis-3 definition

• Sepsis = life-threatening organ dysfunction (SOFA score ≥2) from infection
• Septic shock = Sepsis + vasopressor requirement to maintain MAP ≥65 + serum lactate >2 mmol/L despite adequate fluid resuscitation
• Discarded: SIRS criteria, "severe sepsis" terminology

Q: What is the Surviving Sepsis Campaign Hour-1 Bundle? Which element is most time-sensitive? A: The 5 elements are: lactate measurement, blood cultures, broad-spectrum antibiotics, 30 mL/kg crystalloid bolus, vasopressors for refractory hypotension. Most time-sensitive: Antibiotics - each hour of delay after septic shock recognition increases mortality by ~7-10%. Blood cultures must be drawn before antibiotics but should NOT delay antibiotic administration by >45 minutes.

Q: Why are balanced crystalloids preferred over normal saline in sepsis resuscitation? A: 0.9% NaCl contains 154 mEq/L chloride (supraphysiological vs plasma 102 mEq/L). Large volumes cause: (1) Hyperchloraemic metabolic acidosis (strong ion difference effect), (2) Renal vasoconstriction and AKI (renal cortical perfusion ↓), (3) Coagulopathy. SMART trial (2018) and SALT-ED trial demonstrated balanced crystalloids (LR/PlasmaLyte) had lower major adverse kidney events. Current recommendation: use LR or PlasmaLyte for sepsis resuscitation.

SECTION 7: REGIONAL ANESTHESIA - ASRA 5th EDITION (2025 UPDATE)

Anticoagulant Terminology Change:

• Previous: "prophylactic" vs "therapeutic" dosing
• New: "low dose" vs "high dose"

Updated Minimum Intervals Before Neuraxial:

Q: A patient taking rivaroxaban 20 mg OD for AF needs an urgent epidural for hip fracture. Last dose was 48 hours ago. What do you do? A: 2025 ASRA 5th Edition requires ≥72 hours for rivaroxaban (high dose). At 48 hours, do NOT perform neuraxial block yet. Options: (1) Wait 24 more hours if clinically possible; (2) Check anti-Xa levels (rivaroxaban-specific); (3) If urgent, consider alternative: peripheral nerve block (femoral/adductor canal), GA, or spinal if anti-Xa level negligible. Document risk-benefit analysis.

Q: What is the significance of the new ASRA terminology of "low dose" vs "high dose" vs the old "prophylactic" vs "therapeutic"? A: The old terminology was pharmacologically inaccurate (e.g., a "prophylactic" dose of enoxaparin 40 mg is therapeutic in a 50 kg elderly patient). The new "low dose" vs "high dose" categories are based on actual anticoagulant effect and bleeding risk, making recommendations more clinically accurate and applicable across body weights and renal function levels.

SECTION 8: PERIOPERATIVE NEUROCOGNITIVE DISORDERS (PND)

8.1 New Nomenclature (Adopted 2018, now standard in exams)

• Postoperative delirium (POD): Onset within 7 days of surgery
  • Hyperactive, hypoactive (more common, underrecognised), or mixed
• Delayed neurocognitive recovery (DNCR): Cognitive dysfunction at 30 days post-op (previously "early POCD")
• Postoperative neurocognitive disorder (POCD): Cognitive dysfunction at 30 days to 12 months
• "Postoperative cognitive dysfunction" (POCD) as a blanket term is now discouraged

8.2 Risk Factors:

• Age >65 (most important), pre-existing cognitive impairment, alcohol use, sleep disturbance
• Deep anaesthesia (BIS <40 prolonged), volatile anaesthetics (vs propofol TIVA)
• Hypotension, hypoxia, hypercapnia, hypothermia perioperatively
• Major surgery (cardiac > thoracic > abdominal)

8.3 Meta-analysis 2021 (PMID 34713863):

• Propofol TIVA reduces POCD vs volatile inhalational in elderly: OR 0.52 (95% CI 0.36-0.76)
• Mechanism: Volatile agents (sevoflurane) cause neuroinflammation via tau hyperphosphorylation, amyloid-β deposition in animal models

8.4 Prevention:

• Maintain BIS 40-60 (avoid deep anaesthesia)
• Multimodal analgesia (reduce opioids)
• Maintain haemodynamic stability (MAP >65 mmHg)
• Non-pharmacological: sleep protocols, orientation aids, early mobilisation, sensory aids (hearing aids/glasses in)
• Avoid anticholinergics (benztropine, scopolamine) in elderly

Q: An 80-year-old post major abdominal surgery is agitated and confused on POD 2. How do you assess and manage? A: (1) Assess using CAM (Confusion Assessment Method) - standard delirium assessment tool; (2) Identify and treat precipitants (4 As: Arousal, Attention, Acute change, disorganised thinKing): exclude infection, metabolic derangement, urinary retention, constipation, pain, medication effect (opioids, benzodiazepines), hypoxia, hypoglycaemia; (3) Non-pharmacological first: reorientation, sensory aids, sleep-wake cycle, mobilisation; (4) If pharmacological needed: low-dose haloperidol 0.5-1 mg (first-line), quetiapine; AVOID benzodiazepines (worsen delirium except in alcohol withdrawal); (5) Review and stop offending medications.

SECTION 9: OPIOID-FREE AND OPIOID-SPARING ANAESTHESIA

9.1 Evidence Base (2020-2025 Meta-analyses)

• Less PONV (RR 0.67)
• Less postoperative pain at 24 hrs
• Shorter time to extubation
• No difference in intraoperative haemodynamic stability

1. Dexmedetomidine: 0.5-1 mcg/kg loading dose + 0.2-0.7 mcg/kg/hr infusion
2. Ketamine: Sub-anaesthetic 0.1-0.3 mg/kg bolus/infusion (NMDA antagonism)
3. Lidocaine: IV infusion 1.5 mg/kg bolus + 1.5-2 mg/kg/hr (sodium channel blockade, anti-inflammatory)
4. NSAIDs/COX-2 inhibitors: Ketorolac, celecoxib
5. Paracetamol: 1 g IV 6-hourly
6. Magnesium: 50 mg/kg bolus - NMDA antagonism
7. Regional blocks: Epidural, nerve blocks (TAP block, serratus block, etc.)
8. Alpha-2 agonists (dexmedetomidine, clonidine)

• Obstructive sleep apnea (OSA)
• Chronic opioid users (tolerance)
• High PONV risk
• Respiratory compromise
• Opioid use disorder

• Sub-anaesthetic ketamine (0.1-0.5 mg/kg) as part of multimodal protocol
• Reduces opioid consumption by 25-40% in the first 24h postoperatively
• Particularly useful in opioid-tolerant patients and chronic pain patients
• Prevents opioid-induced hyperalgesia (OIH)
• IV ketamine infusion for acute-on-chronic pain: 0.1-0.35 mg/kg/hr

SECTION 10: POINT-OF-CARE ULTRASOUND (POCUS) - EXPANDED ROLE

10.1 Applications in Anesthesiology (2020-2026)

• Right lateral decubitus position
• Antral cross-sectional area (CSA): <1.0 cm² = empty stomach; >3.5 cm² = full stomach risk
• Grade 0: empty in both supine + RLD; Grade 1: content in RLD only; Grade 2: content in both = full stomach
• Grading helps in: GLP-1 users, obese patients, diabetic gastroparesis, emergency surgery

• A-lines: normal air (horizontal reverberation artefacts)
• B-lines: lung interstitial oedema, pneumonitis, ARDS (≥3 per intercostal space = positive)
• Consolidation: hepatisation pattern; air bronchograms
• Pleural effusion: anechoic space above diaphragm
• Pneumothorax: absent sliding, absent B-lines, lung point = pathognomonic
• BLUE Protocol: Bedside Lung Ultrasound in Emergency for acute respiratory failure

• Assess LV function (LVEF) before induction in emergency/unknown cardiac status
• Detect pericardial effusion/tamponade
• Identify RV strain (McConnell sign, D-sign in parasternal short axis)
• Inferior vena cava (IVC) collapsibility index: >50% collapsibility = fluid responsive

Q: How do you use POCUS to assess gastric content before emergency surgery? A: Scan the gastric antrum in right lateral decubitus (RLD) position using a curved-array probe. Calculate cross-sectional area (CSA) = π × (AP diameter/2) × (CC diameter/2). CSA <1.0 cm² = empty, safe for standard induction. CSA 1.0-3.5 cm² = small volume, assess clinically. CSA >3.5 cm² = significant content, treat as full stomach. Grade 2 (solid or mixed content in both supine and RLD) = high aspiration risk regardless of CSA. Note: liquid content is anechoic; solid content is hyperechoic with 'swirling' appearance.

Q: What is the IVC collapsibility index and what does it predict? A: IVC collapsibility index (CI) = (IVC max diameter - IVC min diameter) / IVC max diameter × 100%. Measured in subxiphoid view. CI >50% with spontaneous respiration (or >12% with positive pressure ventilation) = volume-responsive. IVC max >2.1 cm + CI <50% = elevated CVP, poor fluid responsiveness. Limitations: Affected by respiratory effort, PEEP, TR, RV dysfunction.

SECTION 11: CARDIAC ANESTHESIA & PERIOPERATIVE CARDIAC MANAGEMENT

11.1 2022 ACC/AHA Perioperative Guidelines Updates

• High-risk surgery (intraperitoneal, intrathoracic, suprainguinal vascular)
• Ischaemic heart disease history
• Congestive heart failure
• Cerebrovascular disease
• Insulin-dependent diabetes
• Serum creatinine >2.0 mg/dL Score 0-1 = low risk; 2 = 1% MACE; ≥3 = ≥10% MACE

• Continue if already prescribed (do NOT stop abruptly - rebound ischaemia)
• Do NOT newly start beta-blockers within 24 hours of surgery (DECREASE trial fraud; POISE trial harm: increased stroke)
• May start ≥2-7 days before surgery if high cardiac risk + multiple RCRI factors

• Continue perioperatively (pleiotropic cardioprotective effects)
• Consider starting in patients with cardiac risk

• Aspirin: continue for high cardiac risk patients (do not discontinue for most non-cardiac surgeries)
• Dual antiplatelet therapy (DAPT) after PCI: delay elective surgery
  • Bare metal stent (BMS): ≥30 days
  • Drug-eluting stent (DES, 2nd/3rd gen): ≥3 months (previously 12 months - updated)
  • Do NOT stop P2Y12 inhibitor (clopidogrel/ticagrelor) within first 30 days of DES - risk of in-stent thrombosis

Q: A patient with a drug-eluting coronary stent placed 8 weeks ago needs urgent non-cardiac surgery. How do you manage antiplatelet therapy? A: This is within the minimum safe window for DES (≥3 months recommended for current-generation DES). Options: (1) Delay surgery to 3 months if clinically possible (preferred); (2) If urgent: continue aspirin 75-100 mg perioperatively, stop clopidogrel/ticagrelor 5-7 days pre-op but restart within 24-48 hours post-op; (3) Bridge with short-acting IV antiplatelet (cangrelor, tirofiban) in very high-risk cases; (4) Cardiology consultation mandatory. Discontinuing DAPT too early = risk of catastrophic in-stent thrombosis (50-70% mortality).

SECTION 12: PEDIATRIC ANESTHESIA - KEY UPDATES

12.1 Neurotoxicity of Anesthetic Agents

• FDA Black Box Warning (2016, reinforced): Repeated or prolonged exposure to general anesthetics and sedatives in children <3 years and in pregnant women (third trimester) may affect brain development
• Single, brief exposure (<3 hours): LOW risk based on current evidence
• SmartTots consortium: ongoing research; consensus that necessary surgery should not be delayed based on neurotoxicity concerns alone
• Dexmedetomidine: potential neuroprotective; no clear neurotoxicity shown

12.2 TIVA in Children

• Pharmacokinetic differences: higher volume of distribution, faster clearance in children → higher weight-based propofol doses required
• Propofol Infusion Syndrome (PRIS): Higher risk in children; avoid prolonged high-dose propofol infusions (>4 mg/kg/hr for >48h)
• TIVA preferred in: MH-susceptible, PONV-prone, airway surgery, tonsillectomy

Q: What is the FDA warning regarding anesthetics in children and what is the clinical implication? A: In 2016, the FDA updated labels requiring a warning that repeated or prolonged use of general anesthetics and sedation drugs during surgeries and procedures in children younger than 3 years or in pregnant women during the third trimester may affect the development of children's brains. Implication: (1) Delay elective surgery if possible until age >3; (2) Single, brief (<3 hours) anaesthesia appears safe based on GAS and PANDA trials; (3) Inform parents of theoretical risk; (4) Use minimum effective doses.

SECTION 13: THORACIC ANESTHESIA - KEY UPDATES

13.1 One-Lung Ventilation (OLV) - Current Practice

• Protective OLV: Tidal volume 4-5 mL/kg IBW (smaller than ARDS protocol due to only one lung)
• PEEP 5-8 cmH2O to recruited lung
• Driving pressure ≤14 cmH2O during OLV
• Hypoxic Pulmonary Vasoconstriction (HPV): maximised by volatile agents (less than IV agents)
  • Almitrine (no longer widely available) potentiated HPV
  • Vasodilators (vasopressors, bronchodilators, inhalation NO) affect HPV
• Positioning: lateral decubitus → gravity + HPV improve V/Q matching

13.2 Tools for OLV:

• Left-sided double-lumen tube (DLT): preferred (longer left main bronchus)
• Right-sided DLT: only for left pneumonectomy, left bronchopleuritis
• Bronchial blocker: Arndt blocker, Cohen blocker - useful when DLT not possible (difficult airway, small patient, tracheostomy)

SECTION 14: MONITORING UPDATES

14.1 Depth of Anaesthesia Monitoring - BIS/Entropy

• BIS (Bispectral Index): 0-100 scale; 40-60 = adequate anaesthesia; <40 = deep
• CANTATA trial, B-Unaware trial: BIS-guided vs protocol-based: modest reduction in awareness
• MACE score: Predicted anaesthetic awareness based on risk factors
• High-risk patients for awareness: Cardiac surgery, C-section, emergency surgery, difficult intubation, neuromuscular block without NMBA reversal monitoring
• TIVA without EEG monitoring: Higher awareness risk (cannot see end-tidal agent concentration)

14.2 Intraoperative Neurophysiological Monitoring (IONM)

• SSEP + MEP (somatosensory + motor evoked potentials): spine surgery, aortic surgery
• EEG: carotid endarterectomy, hepatic surgery
• Monitoring agents that suppress IONM: volatile agents (dose-dependent), nitrous oxide, propofol (less), opioids (minimal)
• Anaesthesia for IONM: TIVA (propofol + remifentanil) preferred to preserve signals

14.3 Association of Anaesthetists Monitoring Standards 2021

• SpO2 (pulse oximetry)
• Non-invasive blood pressure
• ECG (3-lead or 5-lead)
• End-tidal CO2 (capnography) - mandatory for every anaesthetic
• Airway gases (O2, volatile agent, N2O if used)
• Neuromuscular monitoring (quantitative, whenever NMBAs used)
• Temperature monitoring (procedures >30 min)

SECTION 15: ADDITIONAL HIGH-YIELD VIVA TOPICS

15.1 Transfusion Medicine Updates

• Restrictive transfusion strategy: Transfuse when Hb <7-8 g/dL (non-cardiac); Hb <8 g/dL (cardiac, hip fracture, elderly)
  • TRICC, TRISS, FOCUS trials support restrictive strategy
• Cell salvage (autologous blood): Preferred in major surgery (cardiac, orthopaedic, hepatic) to avoid allogenic transfusion risks
• Massive Transfusion Protocol (MTP): 1:1:1 ratio (pRBC:FFP:Platelets) or damage control resuscitation
• Viscoelastic testing: TEG (thromboelastography) or ROTEM: guide transfusion in coagulopathy; preferred over standard coagulation tests in major bleeding
• TXA (Tranexamic Acid): Given within 3 hours of trauma (CRASH-2 trial); reduces mortality by 15% in traumatic haemorrhage; also used in obstetric haemorrhage (WOMAN trial), cardiac surgery

15.2 Awareness Under Anaesthesia

• Incidence: 1 in 19,000 (routine) to 1 in 800 (cardiac, C-section, emergency)
• Risk factors: female, young, obesity, TIVA without monitoring, high opioid requirement, chronic benzodiazepine use, cardiac surgery
• 5th National Audit Project (NAP5 UK): Largest study; dreaming ≠ awareness; most awareness occurs at induction/emergence
• Management: Structured assessment (Modified Brice questionnaire); psychological support; formal PTSD screening

15.3 Malignant Hyperthermia (MH) - Current

• Trigger: volatile anaesthetics (halothane, isoflurane, sevoflurane, desflurane) + succinylcholine
• Pathophysiology: Uncontrolled release of Ca²⁺ from sarcoplasmic reticulum (RYR1 mutation)
• Signs: Rapidly rising ETCO2 (earliest sign), muscle rigidity, hyperthermia >38.8°C/hr rise, metabolic/respiratory acidosis, CK rise >20,000 IU/L
• Treatment: Dantrolene 2.5 mg/kg IV (repeat up to 10 mg/kg), cooling measures, bicarbonate, insulin-dextrose for hyperkalaemia
• Avoidance: Total TIVA (propofol + non-depolarising NMBA); flush anaesthesia machine (>10 L/min fresh gas for 20 min before use)

15.4 Latex Allergy

• High-risk: repeated urological procedures (spina bifida), healthcare workers, rubber industry workers
• True Type I IgE-mediated vs Type IV contact dermatitis
• Cross-reactivity with fruits: banana, kiwi, avocado, chestnut ("latex-fruit syndrome")
• Management: Latex-free environment (latex-free gloves, IV ports, endoscopes)
• Treatment of anaphylaxis: Adrenaline 0.3-0.5 mg IM (anterolateral thigh), fluids, hydrocortisone, antihistamine

QUICK REVISION TABLE: HIGH-YIELD NUMBERS FOR VIVA

SOURCES

• Miller's Anesthesia 10e (2020) - Elsevier
• Barash, Cullen & Stoelting's Clinical Anesthesia 9e (2022) - Wolters Kluwer
• Morgan & Mikhail's Clinical Anesthesiology 7e (2022) - McGraw-Hill

• DAS 2025 Difficult Intubation Guidelines (PMID: 41203471)
• ASRA 5th Edition Anticoagulation Guidelines 2025 - Regional anesthesia in antithrombotic therapy
• SSC 2021 Guidelines - Surviving Sepsis Campaign
• ESICM ARDS Guidelines 2023 - New ARDS definition including HFNO/NIV
• Canadian Guidelines to Practice 2025 (PMID: 39900856)
• DAS ATI Guidelines 2020 (PMID: 31729018)
• Opioid-Free Anaesthesia Meta-analysis 2023 (PMID: 37515877)
• GLP-1 Aspiration Risk 2025 (PMID: 40230298)
• Remimazolam vs Propofol 2022 (PMID: 36326772)
• POCUS Guidelines for neonatal/paediatric ICU 2020 (PMID: 32093763)
• Norepinephrine vs Phenylephrine for C-section 2025 (PMID: 40522505)