Monitoring, Sedation, Nutrition and ICU Complications
This domain covers the routine that determines whether ICU patients do well: what you monitor, how deeply you sedate, how you feed, and what the ICU itself does to them. The Board tests bundle elements and the specific harms of common drugs.
Monitoring that changes decisions
Continuous ECG, pulse oximetry, capnography and invasive pressure are standard. Know the limits: pulse oximetry reads falsely high in carbon monoxide poisoning and is unreliable in methaemoglobinaemia, poor perfusion, motion and dark nail polish; the oxygen-haemoglobin dissociation curve shifts with pH, temperature and 2,3-DPG. Capnography confirms tube position and detects disconnection earlier than desaturation. Arterial lines give beat-to-beat pressure, but the mean is the reliable number. CVP is a poor volume gauge. Lactate and central venous oxygen saturation give a supply-demand view. Processed EEG is not routine for sedation depth.
Sedation and delirium
Target RASS -1 to -2, or 0 where tolerated, with analgesia first, then the lightest sedative that works. Daily sedation interruption paired with a spontaneous breathing trial shortens ventilation. Propofol infusion syndrome appears with doses above 4 mg/kg/h or prolonged use: lactic acidosis, rhabdomyolysis, arrhythmia and renal failure - stop the drug. Dexmedetomidine causes bradycardia and hypotension. Screen for delirium with CAM-ICU; antipsychotics do not treat it, and the evidence favours sleep, orientation, early mobility and family presence.
Nutrition and ICU complications
Start enteral feeding within 24-48 hours, provide 25-30 kcal/kg and 1.2-2 g/kg protein, and accept trophic feeding during shock with escalating vasopressors. Do not use gastric residual volumes routinely. Refeeding risk means checking phosphate, potassium and magnesium and giving thiamine before feeding the malnourished. Target glucose 140-180 mg/dL. Prevent what the ICU causes: VAP and CLABSI bundles, DVT prophylaxis, pressure-area care, early mobilisation, and stress ulcer prophylaxis only with risk factors.
Worked example
A 70 kg man has received propofol at 5 mg/kg/h for 5 days and now has unexplained acidosis, creatine kinase 12,000 and a widened QRS. Propofol infusion syndrome is the working diagnosis; cumulative dose is roughly 5 x 70 x 5 x 24 = 42 g. Stop propofol, switch agent, treat the acidosis and arrhythmia, and consider renal replacement for severe rhabdomyolysis.
Traps
Chasing a sedation score with the infusion rate instead of treating pain. Fully feeding a shocked patient. Using antipsychotics routinely for delirium. Dismissing a rising creatinine as just part of ICU care.