Continuous Sedation in Intensive Care

Sedation in intensive care follows an analgesia first, light sedation approach. Most ventilated patients are kept calm and responsive (Richmond Agitation Sedation Scale of minus 1 to 0, or minus 2 to 0), because deep sedation prolongs ventilation, increases delirium and raises mortality.

Deep sedation. Reserved for severe acute respiratory distress needing neuromuscular blockade, raised intracranial pressure, status epilepticus, and refractory agitation. Targets of minus 4 to minus 5, or burst suppression on EEG, are set by the clinical indication.

Daily review. Do a daily spontaneous awakening test or interrupt sedation unless contraindicated, and screen for delirium with the CAM-ICU.

First line. Propofol or dexmedetomidine, with an opioid for pain.

Avoid benzodiazepines as routine agents because they cause delirium. Use midazolam for alcohol withdrawal, status epilepticus, and when other agents are unsuitable.

Adjuncts. Ketamine infusion for opioid-sparing or refractory pain, clonidine, and inhaled sedation where available.

Special groups.

• Children: weight-based dosing, with propofol avoided for prolonged infusion in young children.

• Pregnancy: use the lowest dose and avoid prolonged benzodiazepines.

• Hepatic or kidney failure: midazolam accumulates with its active metabolite.

• East Africa: where only midazolam and an opioid are available, use the lowest rate, interrupt daily, and monitor for delirium.

• Propofol: start 5 micrograms/kg/min, increase every 5 to 10 minutes, usual 5 to 50 micrograms/kg/min (0.3 to 3 mg/kg/h), maximum 4 mg/kg/h.

• Dexmedetomidine: 0.2 to 1.4 micrograms/kg/h, starting at 0.2 to 0.7. Avoid a loading dose.

• Midazolam: 0.02 to 0.1 mg/kg/h (1 to 7 mg/h in adults).

• Ketamine: 0.05 to 0.4 mg/kg/h.

Monitoring. Assess sedation depth and pain every 4 hours and with each change. For propofol, check triglycerides every 48 to 72 hours and count calories from the lipid (1.1 kcal/mL). Check heart rate for dexmedetomidine.

Weaning. After more than 5 days of benzodiazepine or opioid infusion, reduce by 10 to 25 percent each day to avoid withdrawal.

Stop rules. Stop propofol or reduce for triglycerides over 5 mmol/L, or any sign of propofol infusion syndrome (unexplained metabolic acidosis, rhabdomyolysis, hyperkalaemia, rising lactate, ECG changes, cardiac failure), mainly at doses over 4 mg/kg/h for over 48 hours. Reduce dexmedetomidine for bradycardia under 50 beats each minute or hypotension.

Referral and escalation. Seek senior review for agitation not controlled at two agents, delirium needing antipsychotics, and withdrawal.

Common errors. Oversedation without a daily review, using benzodiazepines routinely, continuing propofol at high dose beyond 48 hours, and forgetting analgesia.