Post Cardiac Arrest Medication Considerations

After return of circulation the aims are to protect the brain and heart: normal oxygenation, perfusion pressure, glucose and temperature, and prompt treatment of the cause. Drug choices affect later prognostic assessment, so short-acting agents are used.

Targets.

• Oxygen saturation 94 to 98 percent, avoiding hyperoxia.

• PaCO2 4.5 to 6.0 kPa (35 to 45 mm Hg).

• Mean arterial pressure of 65 mm Hg or more.

• Glucose 7.8 to 10 mmol/L, avoiding hypoglycaemia.

• Potassium 4.0 to 5.0 mmol/L.

• Temperature controlled below 37.5 degrees Celsius, with deliberate cooling to 32 to 36 degrees for at least 24 hours in selected comatose patients.

Hypothermia and drugs. Cooling slows clearance of opioids, sedatives and neuromuscular blockers by up to 30 to 50 percent, so doses are reduced and accumulation is monitored.

Haemodynamics. Noradrenaline first line. Dobutamine for low cardiac output.

Sedation and analgesia. Propofol with fentanyl or remifentanil. Avoid long-acting benzodiazepines.

Seizures and myoclonus. Levetiracetam, valproate or propofol. Prophylactic antiepileptic drugs are not given.

Antithrombotic therapy. Aspirin and anticoagulation when acute coronary syndrome is suspected, with urgent angiography for ST elevation.

Not routine. Corticosteroids, prophylactic antibiotics, and prophylactic antiarrhythmics.

Special groups.

• Children: weight-based dosing and specialist critical care.

• Pregnancy: left lateral position and obstetric involvement.

• East Africa: where cooling is not available, aim for strict normothermia, treat fever with paracetamol and external cooling, and treat reversible causes such as malaria, hypoglycaemia and poisoning.

• Noradrenaline: start 0.05 micrograms/kg/min, titrated to a mean arterial pressure of 65 mm Hg or more.

• Dobutamine: 2.5 to 20 micrograms/kg/min.

• Propofol: 5 to 50 micrograms/kg/min. Fentanyl 25 to 200 micrograms/h.

• Paracetamol: 1 g every 6 hours, maximum 4 g daily.

• Shivering: skin counter-warming, and if needed cisatracurium 0.15 mg/kg intravenously, with deep sedation.

• Levetiracetam: 60 mg/kg intravenously (maximum 4500 mg) for seizures, then maintenance by kidney function.

• Aspirin: 300 mg orally or by tube, then 75 mg daily. Heparin 5000 units intravenously for acute coronary syndrome before angiography.

• Insulin infusion: when glucose is over 10 mmol/L.

• Stress ulcer prophylaxis: pantoprazole 40 mg daily in ventilated patients at risk. Enoxaparin 40 mg daily for thromboprophylaxis (20 mg if creatinine clearance is under 30 mL/min).

Monitoring. Arterial line, 12-lead ECG, echocardiography, lactate, glucose hourly at first, electrolytes, temperature continuously, blood gases, and EEG for suspected seizures or myoclonic status.

Stop rules. Limit sedation to what is needed. Stop sedatives and neuromuscular blockers well before neurological prognostic assessment, usually at least 72 hours after reaching normal temperature, because drug effects mislead.

Referral and escalation. Seek urgent cardiology review for ST elevation, shock needing mechanical support, or recurrent arrhythmia. Seek neurology for myoclonic status and prognostic assessment.

Common errors. Hyperoxia, hypotension, missing hypoglycaemia, long-acting sedatives, and early prognostic decisions while sedated or cooled.