Intensive Care
The intensive care domain tests shock recognition, sepsis bundles, respiratory support, sedation, and organ replacement. Final MCQ stems often contrast a physiological target with a protocolised number, or ask which intervention comes first.
Core rules
- Sepsis-3: sepsis is life-threatening organ dysfunction caused by a dysregulated response to infection, defined as a SOFA increase of ≥2. Septic shock is vasopressor-requiring hypotension with MAP ≥65 mmHg and lactate >2 mmol/L after adequate fluids.
- Initial sepsis: take blood cultures before antibiotics if this does not delay treatment; give broad-spectrum antibiotics within 1 hour for septic shock; give 30 mL/kg crystalloid for hypotension or lactate ≥4 mmol/L, then reassess fluid responsiveness.
- ARDS: Berlin criteria require P/F ≤300 with PEEP ≥5, bilateral opacities, and no purely cardiac cause. Ventilate at 6 mL/kg predicted body weight, plateau ≤30 cmH2O, driving pressure ≤15 cmH2O, and prone for 16 hours/day if P/F <150.
- Sedation and delirium: target light sedation, use daily interruption, screen with CAM-ICU, and avoid benzodiazepines where possible.
- Renal replacement: CRRT for refractory hyperkalaemia, acidosis, fluid overload, uraemia, or toxin removal.
- Transfusion: restrictive threshold Hb 7 g/dL, with 7–8 g/dL in ischaemic heart disease.
Worked example
A 175 cm man with ARDS weighs 95 kg. Predicted body weight = 50 + 0.91 × (175 − 152.4) = 70.6 kg. Initial tidal volume = 6 × 70.6 = 424 mL. Set 420 mL, adjust respiratory rate to pH, and use a PEEP table. If plateau pressure is 32 cmH2O, reduce tidal volume toward 5 mL/kg before escalating PEEP, because plateau pressure reflects alveolar distension.
Traps that cost marks
- Using actual body weight for tidal volume in ARDS.
- Continuing fluids after the patient is no longer fluid responsive.
- Delaying antibiotics to obtain cultures in shock.
- Calling qSOFA a diagnostic test; it is a bedside prompt.
- Overlooking permissive hypercapnia contraindications such as raised intracranial pressure.
- Assuming a normal lactate excludes shock.