• Q21: TPN formula (3:1) calculation for 70kg man with enterocutaneous fistula + TPN monitoring (2023)
• Q22: Nutritional augmentation in surgical patients (NRS-2002) (2020)
• Q23: Role of nutrition and methods in surgical patients / indications and techniques of supplementing nutrition (2017/2019)
• Q24: Indications/contraindications of parenteral nutrition, monitoring, complications, catheter issues, home PN (2011/2013)
• Q25: Immunonutrition in surgical patients (2014)
• Q26: Percutaneous endoscopic gastrostomy (2010)
• Q27: ABG, metabolic alkalosis, metabolic acidosis - causes, management, complications/significance (2020)
• Q28: Clinical features and management of hypokalemia (2020)
• Q29: Clinical approach to hyponatremia, post-op hyponatremia, etiology and management (2019)
• Q30: Flow-guided fluid therapy, role of colloids as resuscitation fluids (2017)
• Q31: Recent strategy for assessment/monitoring of IV fluids and electrolytes in peri-operative period (2021)
• Q32: Peri-operative fluid management (2013)
• Q33: Zero fluid balance concept in perioperative fluid management (2016)
• Q34: Post-operative IV fluid protocol after major GI surgery + composition of RL (2021)
• Q35: Classify shock, pathophysiology, management (endotoxic)
• Q36: Role of vasoactive drugs in shock (2023)

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MS GENERAL SURGERY - EXAM ANSWERS

Nutrition | Fluid, Electrolytes & Acid-Base | Shock

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SECTION A: NUTRITION IN SURGICAL PATIENTS

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Q21. Calculate the composition of 3:1 TPN formula required for a 70kg man with an enterocutaneous fistula. How do you monitor a patient receiving TPN? (2023)

DEFINITION

CALCULATION FOR 70 kg MAN (ECF = hypermetabolic state)

• Stressed patient (ECF, sepsis risk) = 30-35 kcal/kg/day
• = 30 × 70 = 2100 kcal/day (use 2100-2500 kcal)

• Na: 0.9-1.2 mmol/kg = 70-84 mmol
• K: 1 mmol/kg = 70 mmol
• Phosphate: 20-30 mmol (essential - prevents hypophosphataemia)
• Ca: 5 mmol; Mg: 1 mmol

MONITORING TPN PATIENT

• Daily weight, fluid balance, vitals
• Catheter site inspection daily (line sepsis in up to 15%)
• Look for signs of refeeding syndrome: arrhythmia, oedema, weakness

• Strict aseptic technique; paired blood cultures if fever
• CXR post-insertion: tip at inferior third SVC or atrioventricular junction
• No femoral lines for PN

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Q22. Discuss nutritional augmentation in surgical patients (NRS-2002) (2020)

DEFINITION

NUTRITIONAL RISK SCREENING - NRS 2002

• Score ≥3 = patient is at nutritional risk → start nutritional support
• Components: impaired nutritional status score + disease severity score + age adjustment (+1 if >70 years)

ASSESSMENT - ABCD

• Anthropometry: BMI, MUAC, TSF, MAMC, % weight change
• Biochemistry: albumin, CRP, WBC, Hb, electrolytes, phosphate
• Clinical: symptoms (nausea, dysphagia, diarrhoea), comorbidities
• Dietary: food diary, calorie intake vs calculated requirements

INDICATORS FOR SUPPORT

• BMI <18.5 + wt loss >10% in 3-6 months
• OR BMI <20 + wt loss >5% in 3-6 months

ROUTES OF AUGMENTATION (Enteral preferred over Parenteral)

1. Oral supplements (ONS) - 200 kcal/200 mL carton, 2 g N per carton
2. Nasogastric/nasojejunal tube feeding - 10-20 mL/h → 75 mL/h
3. Gastrostomy/jejunostomy (surgical or PEG/PEJ)
4. Supplemental/Total Parenteral Nutrition - when enteral not possible

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Q23. Discuss the role of nutrition and its methods in surgical patients / Indications and techniques of supplementing nutrition in surgical patients (2017/2019)

WHY NUTRITION MATTERS IN SURGERY

• Metabolic response to surgery causes insulin resistance, catabolism, negative nitrogen balance
• Counter-regulatory hormones (adrenaline, cortisol, glucagon, GH) increase energy requirements up to 40 kcal/kg/day in severe stress
• Malnutrition → impaired wound healing, infection, prolonged stay, increased mortality

CALCULATING REQUIREMENTS

• Energy: 25-35 kcal/kg ideal body weight/day
• Protein: 0.15 g N/kg/day (normal) → 0.25 g N/kg/day (ill patient) = 1.5 g protein/kg/day
• Carbohydrate: 45-65% total calories; glucose minimum 100-200 g/day
• Fat: 30-50% calories; 100-200 g/week long chain triglycerides

METHODS (Enteral > Parenteral - always preferred)

• Supplemental PN: enteral feeding inadequate
• TPN: enteral route impossible (short bowel syndrome, ECF, ileus, obstruction)
• Via PICC (weeks-months) or CVC (subclavian/IJV, tip at SVC/atrial junction)
• 3-litre bag: lipid emulsion + amino acids + glucose + electrolytes + vitamins + trace elements
• Energy ratio: 150-250 kcal per g of protein N; 30-50% energy from fat

• Pre-op CHO loading (carbohydrate drinks 2 hr pre-op)
• Minimise fasting; early post-op oral/enteral feeding
• Minimally invasive surgery where possible

MONITORING (see Q21)

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Q24. Indications and contraindications of PN; monitoring; complications; catheter issues; Home PN (2011/2013)

INDICATIONS FOR PN

• Short bowel syndrome (massive intestinal resection, <200 cm small bowel)
• Intestinal fistulation (enterocutaneous fistula - high output)
• Severe gut failure/ileus
• Acute severe pancreatitis (if enteral not tolerated)
• Bowel obstruction, radiation enteritis
• Severe inflammatory bowel disease unresponsive to treatment
• Pre-op optimization in severely malnourished patients when surgery needs to be delayed
• Post-major GI surgery when enteral route unavailable

CONTRAINDICATIONS

• Functional gut available (relative - enteral always preferred)
• Short expected duration (<7 days)
• Haemodynamic instability (correct first)
• No vascular access possible

MONITORING (See Q21)

COMPLICATIONS

• Pneumothorax (0.5-1%, most common with subclavian approach)
• Line misplacement (confirm on CXR - tip at inferior 1/3 SVC/AV junction)
• Arterial puncture, haemothorax, air embolism

• Line sepsis (most important - up to 15% of patients; → septicaemia, fungal infections causing uveitis and endocarditis)
• Management: paired blood cultures (line + peripheral), stop line use, remove if cultures positive, antibiotics
• Line thrombosis: SVC occlusion, PE → anticoagulate

• Refeeding syndrome (hypophosphataemia, K, Mg, Ca shifts - arrhythmia, respiratory failure, death)
• Hyperglycaemia (use variable insulin infusion)
• Hypoglycaemia (when PN interrupted without adjusting insulin)
• Liver dysfunction/fatty liver (>25% long-term) → IFALD (intestinal failure-associated liver disease)
• Metabolic bone disease
• Vitamin deficiencies (B12, fat-soluble A,D,E,K)

CATHETER ISSUES IN PN

• PICC (basilic > cephalic/brachial vein): weeks to months; preferred long-term
• CVC (subclavian/IJV): check CXR post-insertion; AVOID femoral lines (infection risk)
• Tunnelled catheters / implanted ports (Hickman, Port-a-cath): for Home PN
• Occlusion treated with urokinase/tPA instillation
• Infection: antibiotic lock therapy or line removal

HOME PARENTERAL NUTRITION (HPN)

• Indication: long-term intestinal failure (short bowel, chronic motility disorder, radiation enteritis)
• Via tunnelled central venous catheter or implanted port
• Overnight infusion (12-16 hr/day) to allow daytime freedom
• Patient and carer training essential
• Regular monitoring: micronutrients (Zn, Cu, Se, ferritin, B12, Vit D) - every 3 months
• Complications: IFALD, metabolic bone disease, sepsis
• Multidisciplinary team: surgeon, dietitian, nurse, pharmacist

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Q25. Immunonutrition in surgical patients (2014)

DEFINITION

KEY IMMUNONUTRIENTS

INDICATIONS

• Major elective GI surgery (upper GI especially)
• Critically ill surgical patients (ICU)
• Severe trauma and burns
• Patients at high nutritional risk (NRS-2002 ≥3)

EVIDENCE (Bailey & Love 28e)

• ESPEN guidelines support pre-op immunonutrition for 5-7 days before major GI surgery
• Combination feeds (arginine + omega-3 + nucleotides) most evidence
• Reduces: infectious complications, anastomotic leak rate, length of stay
• Glutamine supplementation in PN associated with reduced infections in ICU patients

REFEEDING SYNDROME (bonus scoring point)

• Monitor phosphate, K, Mg, Ca when starting feeds in malnourished patients
• Start at 10 kcal/kg/day max; supplement thiamine (vitamin B1) before feeds

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Q26. Percutaneous Endoscopic Gastrostomy (PEG) (2010)

DEFINITION

INDICATIONS

• Long-term enteral feeding (>4 weeks) when oral intake inadequate
• Neurological dysphagia (stroke, MND, head injury, Parkinson's, dementia)
• Head and neck cancers (post-radiation, post-surgery)
• Oesophageal obstruction (malignancy)
• Cystic fibrosis, failure to thrive
• Chronic respiratory failure requiring nocturnal feeding

CONTRAINDICATIONS

• Absolute: inability to perform upper GI endoscopy, inability to transilluminate anterior abdominal wall, previous total gastrectomy
• Relative: ascites, peritoneal dialysis, coagulopathy, obesity, gastric varices, previous abdominal surgery

TECHNIQUE (Pull/Push/Introducer Methods)

1. Patient supine; IV sedation/LA
2. Upper GI endoscopy; stomach insufflated; transilluminate anterior abdominal wall
3. Skin incision + needle cannula puncture into stomach under endoscopic vision
4. Guidewire passed through cannula into stomach; grasped by endoscope
5. Wire pulled out through mouth
6. PEG tube attached to wire; pulled back down oesophagus and through abdominal wall
7. Internal bumper secures tube against gastric wall; external disk/clamp secures at skin

POST-PROCEDURE

• CXR/X-ray at 4 hours if any concern
• Feed commenced within 4-6 hours
• Tube site cleaned daily; inspect for buried bumper, cellulitis, leakage

COMPLICATIONS

REPLACEMENT/REMOVAL

• PEG can be removed when no longer needed (endoscopically or traction if balloon type)
• Replaced by balloon gastrostomy button after tract established (4-6 weeks)

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SECTION B: FLUID, ELECTROLYTES & ACID-BASE BALANCE

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Q27. Describe ABG, metabolic alkalosis, metabolic acidosis - causes, management, complications/significance (2020)

NORMAL ABG VALUES

STEP-BY-STEP ABG INTERPRETATION

1. pH → acidaemia (<7.35) or alkalaemia (>7.45)?
2. Primary disorder: ↓pH + ↑CO2 = resp. acidosis; ↓pH + ↓HCO3 = met. acidosis
3. Compensation: appropriate?
4. Anion gap = Na - (Cl + HCO3) [Normal: 8-12 mEq/L]
5. Delta-delta (if AG elevated): rule out mixed disorders

METABOLIC ACIDOSIS

• M - Methanol; U - Uraemia; D - DKA; P - Propylene glycol; I - Isoniazid/Iron; L - Lactic acidosis; E - Ethylene glycol; S - Salicylates

• Diarrhoea, fistulae (small bowel), RTA, Acetazolamide, Addison's, NH4Cl, Saline excess (hyperchloraemic)

• Shock (lactic acidosis - most common surgical cause; lactate >2 mmol/L = tissue hypoperfusion)
• ECF/fistula (HCO3 loss)
• Sepsis, post-op ARF

• Treat underlying cause (most important)
• Fluid resuscitation in shock/lactic acidosis
• NaHCO3 only if pH <7.1 (controversial; risk CO2 paradox)
• Dialysis for uraemic acidosis
• Target lactate clearance >10%/hr in ICU

METABOLIC ALKALOSIS

• Chloride-responsive: IV 0.9% saline + KCl replacement; stop NGT aspiration
• Pyloric stenosis: resuscitate with 0.9% saline + KCl; surgery (pyloroplasty) ONLY after biochemical correction
• Chloride-resistant: treat underlying cause (aldosterone antagonists)

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Q28. Clinical features and management of hypokalemia (2020)

DEFINITION

SEVERITY

• Mild: 3.0-3.5 mEq/L; Moderate: 2.5-3.0; Severe: <2.5

CAUSES

CLINICAL FEATURES (Severity-dependent)

• Muscle weakness (proximal > distal), fatigue, cramps
• Hypo/areflexia in severe cases
• Respiratory muscle weakness → respiratory failure (K <2.5)
• Paralytic ileus (smooth muscle)

• ECG: flattened/inverted T waves, U waves (hallmark), ST depression, prolonged QU interval
• Arrhythmias: PVCs, AF, VT, VF (especially with digoxin)
• Cardiac arrest in severe (<2.0)

• Nephrogenic DI (polyuria, polydipsia)
• Metabolic alkalosis (H+ moves into cells as K+ moves out)

MANAGEMENT

• KCl slow-release tablets; 40-80 mmol/day; divided doses

• Rate: max 20 mmol/hr peripherally; up to 40 mmol/hr centrally (with continuous ECG monitoring)
• Concentration: max 40 mmol/L peripherally; higher only via CVC
• Never give IV K+ as bolus - risk of cardiac arrest
• Replace Mg2+ simultaneously (hypomagnesaemia perpetuates hypokalaemia)

• Stop offending drugs (diuretics)
• Treat underlying cause
• In refractory hypokalaemia: check and correct hypomagnesaemia first

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Q29. Clinical approach to hyponatremia; post-operative hyponatremia; etiology and management (2019)

DEFINITION

CLASSIFICATION

CLINICAL FEATURES (based on severity)

• Mild (Na 130-135): anorexia, nausea, malaise
• Moderate (Na 125-130): headache, lethargy, confusion
• Severe (Na <125): seizures, coma, cerebral oedema → death
• Rate of fall more important than absolute level

POST-OPERATIVE HYPONATREMIA

• Stress response → ADH (vasopressin) surge → free water retention
• Administration of hypotonic IV fluids (5% dextrose, 0.45% saline) intraoperatively/post-op
• NGT losses replaced with hypotonic solutions
• Pain, nausea → non-osmotic ADH release

MANAGEMENT

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Q30. Flow-guided fluid therapy; colloids as resuscitation fluids (2017)

FLOW-GUIDED / GOAL-DIRECTED FLUID THERAPY (GDFT)

• Both fluid under-resuscitation (AKI, gut ischaemia) and over-resuscitation (pulmonary oedema, anastomotic leak, ileus) are harmful
• Standard monitoring (HR, BP, urine output) poor predictors of fluid responsiveness

• Post-operative complications
• Anastomotic leak rate
• Length of hospital stay
• Time to return of gut function

COLLOIDS AS RESUSCITATION FLUIDS

• SAFE trial: Albumin = saline in general ICU (except TBI where albumin worse)
• CHEST trial: HES 6% increased risk of AKI and renal replacement therapy vs. saline
• HES banned/restricted in many countries due to nephrotoxicity and coagulopathy
• Gelatins: no proven benefit over crystalloids; risk of anaphylaxis

• No benefit for albumin outside specific indications (ascites replacement, liver failure, SBP prophylaxis)
• Balanced crystalloids (Hartmann's/Plasmalyte) preferred over NS for resuscitation
• Best fluid for haemorrhage = blood
• Avoid HES in ICU/surgical patients

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Q31. Recent strategy for assessment and monitoring of IV fluids and electrolytes in peri-operative period (2021)

BACKGROUND

MODERN MONITORING STRATEGY

• Pulse, BP, capillary refill time, JVP
• Urine output (target: >0.5 mL/kg/hr)
• Fluid balance charts (ins + outs including drains, fistulae, NG losses)
• Weight (daily - 1 kg ≈ 1 L fluid)

• Serum electrolytes (Na, K, Mg, Ca, PO4): daily or more frequently post-major surgery
• Lactate: marker of tissue perfusion; target <2 mmol/L; clearance >10%/hr
• ABG: acid-base status, BE, HCO3
• Urine Na: low (<20 mEq/L) = hypovolaemia; high = SIADH or AKI
• Serum osmolality

• Use the "5 Rs" framework: Resuscitation, Routine maintenance, Replacement, Redistribution, Reassessment
• Isotonic fluids for maintenance; avoid excessive 0.9% saline (hyperchloraemic acidosis)
• Target: 25-30 mL/kg/day water; 1 mmol/kg/day Na, K, Cl; 50-100 g/day glucose

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Q32. Peri-operative fluid management (2013)

PRINCIPLES

1. Maintain intravascular volume
2. Preserve organ perfusion
3. Correct electrolyte/acid-base disturbances
4. Avoid fluid overload (pulmonary oedema, gut oedema → ileus, anastomotic leak)

DAILY MAINTENANCE (70 kg adult)

• Water: ~2.5 L/day (30-35 mL/kg); urine 1.5 L + insensible 0.9 L + faeces 0.1 L
• Na: 70-84 mmol/day (0.9-1.2 mmol/kg)
• K: 70 mmol/day (1 mmol/kg)
• Glucose: 50-100 g/day (prevents catabolism, ketosis)

IV FLUIDS - COMPOSITION TABLE (Bailey & Love 28e, Table 25.2)

PHASES OF PERIOPERATIVE FLUID MANAGEMENT

• NBM minimum time (2hr clear fluids, 6hr solids) - ERAS
• Pre-op CHO drinks (carbohydrate loading)
• Correct existing deficits

• Anaesthetic vasodilation → relative hypovolaemia → balanced crystalloids to maintain MAP
• Replace surgical blood loss (blood after 1-1.5L loss; FFP:RBC:platelet = 1:1:1 in massive haemorrhage)
• Avoid fluid excess (Goal-Directed Fluid Therapy preferred)
• Hartmann's/Plasmalyte preferred over 0.9% saline (less hyperchloraemic acidosis)

• IV maintenance until oral fluids tolerated
• Replace ongoing losses (drains, NG, stoma, fistula)
• Switch to oral route ASAP (ERAS)
• Target urine output >0.5 mL/kg/hr; monitor electrolytes daily

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Q33. Concept of zero fluid balance in perioperative fluid management (2016)

DEFINITION

RATIONALE / EVIDENCE

• Surgical patients traditionally received 3-5 L excess fluid perioperatively
• Each litre of excess fluid → systemic oedema, gut oedema, ileus, impaired wound healing
• Wet tissue = poor outcomes: anastomotic leak, pulmonary oedema, AKI, prolonged ITU stay
• Zero/near-zero or slightly positive fluid balance (< +500 mL) in major GI surgery = better outcomes

PHYSIOLOGICAL BASIS

• Capillary Starling equilibrium disrupted in surgical stress (endothelial glycocalyx damage)
• Excess crystalloid distributes to interstitium (3:1 ratio for crystalloids)
• Oedematous bowel → delayed gastric emptying, poor anastomotic healing, infection
• Sodium and water retention post-op due to ADH, aldosterone, cortisol

HOW TO ACHIEVE ZERO FLUID BALANCE

1. Preoperative: ERAS protocol (CHO drinks, minimal fasting, avoid traditional bowel prep)
2. Intraoperative: GDFT (oesophageal Doppler/SV-guided); replace blood loss with blood; restrict crystalloids to <2 L
3. Postoperative: Switch to oral ASAP; restrict IV fluids after adequate volume established; target UO 0.5-1 mL/kg/hr (avoid chasing urine output with excessive fluids)
4. Daily review: Weight + fluid balance chart; aim cumulative balance near zero by Day 3-5

LIMITATIONS

• Not applicable in haemorrhagic shock or large bowel losses
• Requires meticulous measurement
• Intra-operative insensible losses are difficult to quantify

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Q34. Post-operative IV fluid protocol after major GI surgery and composition of Ringer's Lactate (2021)

POST-OP IV FLUID PROTOCOL - MAJOR GI SURGERY

• Continue intraoperative haemodynamic support
• Target: MAP >65 mmHg, UO >0.5 mL/kg/hr, lactate trending down
• Use vasopressors (noradrenaline) to treat vasodilation rather than excess fluids
• Fluid challenge (250 mL over 10-15 min) only if evidence of hypovolaemia

• IV maintenance only: 25-30 mL/kg/day balanced crystalloid (Hartmann's preferred)
• Add K+ 40 mmol per litre bag
• Replace documented losses: NG aspirate (0.9% saline + KCl), stoma output, drains
• Avoid 5% dextrose alone (hyponatraemia risk)
• Avoid large-volume 0.9% saline (hyperchloraemic acidosis)

• Daily electrolytes: correct Na, K, Mg as needed
• Monitor for post-op hyponatraemia (ADH surge)
• Aim to reduce IV fluids as oral intake resumes
• ERAS: Encourage oral fluids from Day 1; free clear fluids if tolerated

• Stop IV fluids when oral intake >1500 mL/day
• Ensure adequate analgesia and anti-emetics to facilitate early oral intake

• Do NOT give >500 mL IV bolus without reassessment
• Do NOT prescribe unlimited "keep vein open" orders
• Do NOT give hypotonic fluids (0.45% saline, 5% dextrose) as routine maintenance

COMPOSITION OF RINGER'S LACTATE (Hartmann's Solution)

• More physiological electrolyte profile (mirrors plasma better)
• Lower Cl- load → less hyperchloraemic metabolic acidosis
• Lactate converted to HCO3- by liver (mild alkalinising effect)
• Preferred fluid in major GI, hepatobiliary and vascular surgery

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SECTION C: SHOCK AND HAEMORRHAGE

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Q35. Classify shock, discuss pathophysiology, management of shock (endotoxic/septic) (Year Q)

DEFINITION

CLASSIFICATION (Bailey & Love - Mechanism-Based)

1. Haemorrhagic/Hypovolaemic - reduced circulating volume (haemorrhage, vomiting, diarrhoea, third-spacing)
2. Cardiogenic - pump failure (MI, dysrhythmias, cardiomyopathy, valve disease, myocardial contusion)
3. Obstructive - mechanical obstruction of cardiac filling (tamponade, tension PTX, massive PE, air embolism)
4. Distributive - vasodilatation + maldistribution (Septic/endotoxic, anaphylactic, neurogenic)
5. Endocrine - adrenal insufficiency, thyroid crisis

PATHOPHYSIOLOGY OF SEPTIC/ENDOTOXIC SHOCK

• Tissue hypoperfusion → aerobic → anaerobic metabolism → lactic acid → metabolic acidosis
• Glucose depletion → Na/K pump failure → lysosomal autodigestion → cell lysis → hyperkalaemia

• Hypoxia + acidosis → complement activation → leukocyte priming → oxygen free radicals + cytokines → endothelial injury → capillary leak → tissue oedema → worsens cellular hypoxia

• Vasodilation (iNOS-mediated NO overproduction) → ↓SVR → ↓afterload → initially ↑CO (warm, bounding pulses, warm peripheries)
• Later: myocardial depression (TNF-α, IL-1) → ↓CO; relative hypovolaemia from capillary leak

• Baroreceptor → ↑sympathetic → tachycardia, vasoconstriction (except distributive)
• ↑RR → respiratory alkalosis (compensates metabolic acidosis)
• RAA axis + ADH → Na/H2O retention, ↓urine output

STAGES OF SHOCK

MANAGEMENT OF SEPTIC/ENDOTOXIC SHOCK (Surviving Sepsis Bundle)

1. A-B-C: Airway, O2 (target SpO2 >94%), intubation if GCS <8
2. 2 large-bore IV cannulae (14-16G antecubital)
3. Blood cultures (2 sets, peripheral + central) BEFORE antibiotics
4. Broad-spectrum antibiotics within 1 hour of recognition (e.g. Pip-Taz + Metronidazole; or Meropenem if severe/resistant)
5. IV fluid resuscitation: 30 mL/kg balanced crystalloid (Hartmann's) within 3 hours if hypotension/lactate >4
6. Vasopressors if MAP <65 mmHg despite adequate fluids: Noradrenaline (first-line), target MAP ≥65 mmHg
7. Lactate measurement - if >2 mmol/L = sepsis-induced tissue hypoperfusion

• ICU admission; arterial line + CVC
• Source control: Identify and drain/debride/remove infective focus (laparotomy, percutaneous drain)
• Vasopressor: Noradrenaline 0.01-3 mcg/kg/min; add vasopressin if refractory
• Corticosteroids if vasopressor-refractory septic shock: Hydrocortisone 200 mg/day IV
• Glucose control (target 6-10 mmol/L)
• DVT prophylaxis, stress ulcer prophylaxis
• Target: UO >0.5 mL/kg/hr; lactate clearance; MAP ≥65; ScvO2 ≥70%

• Hourly UO, continuous ECG, pulse oximetry
• ABG (lactate, pH, BE) 2-4 hourly
• CVP (8-12 cmH2O); ScvO2 via CVC
• Regular electrolytes, FBC, CRP, procalcitonin

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Q36. Role of vasoactive drugs in shock (2023)

CLASSIFICATION OF VASOACTIVE DRUGS

SPECIFIC PROTOCOLS BY SHOCK TYPE

MONITORING EFFICACY

• MAP ≥65 mmHg (target)
• UO >0.5 mL/kg/hr
• Lactate clearance
• ScvO2 ≥70%
• Skin perfusion improvement (capillary refill <2 sec)
• Wean vasopressors when MAP stable without escalating doses

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QUICK EXAM SCORING TIPS

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What You Got

Section A - Nutrition (Q21-Q26)

• Q21 - TPN 3:1 formula calculation (with the actual numbers for 70 kg) + monitoring schedule
• Q22 - NRS-2002 scoring tool explained + nutritional augmentation methods
• Q23 - Metabolic response to surgery, all routes of nutritional support (enteral > parenteral hierarchy)
• Q24 - Full PN indications/contraindications, 3-category complications, catheter issues, Home PN (HPN)
• Q25 - 4 key immunonutrients (glutamine, arginine, omega-3, nucleotides) with mechanisms + ESPEN evidence
• Q26 - PEG - indications, step-by-step pull technique, complications table, replacement

Section B - Fluid, Electrolytes & Acid-Base (Q27-Q34)

• Q27 - ABG normal values, MUDPILES for high-AG acidosis, chloride-responsive vs. resistant alkalosis table
• Q28 - Hypokalemia: U waves on ECG, IV K+ rate limits (20 mmol/hr peripheral, 40 central), Mg co-replacement
• Q29 - Hyponatremia by osmolality+volume classification, post-op mechanism, 8-10 mmol/24hr correction rule
• Q30 - GDFT algorithm, SAFE/CHEST trial evidence against colloids
• Q31 - 5-tier monitoring strategy, NICE 5Rs, lactate targets
• Q32 - Perioperative 4-phase fluid management + RL vs. NS comparison table
• Q33 - Zero fluid balance concept, ERAS integration, physiological basis
• Q34 - Post-major GI surgery 4-phase IV fluid protocol + Hartmann's exact composition table

Section C - Shock (Q35-Q36)

• Q35 - 5-type classification, full septic shock pathophysiology, surviving sepsis 1-hour and 6-hour bundles, stages table
• Q36 - Full drug classification table with receptors, doses, and shock-type-specific protocols