Emergency Sedation Medicines

Emergency sedation medicines calm an agitated or violent patient to allow safe assessment, or provide sedation and analgesia for painful procedures. De-escalation and treating the cause (hypoglycaemia, hypoxia, intoxication, pain, delirium) come first. Drug choice depends on the likely cause, the route available, and the risk to breathing and blood pressure.

Classification. Benzodiazepines (midazolam, lorazepam, diazepam); antipsychotics (haloperidol, olanzapine, droperidol); ketamine; propofol; dexmedetomidine; reversal agents (flumazenil, naloxone).

Mechanism. Benzodiazepines and propofol enhance GABA. Antipsychotics block dopamine receptors. Ketamine blocks NMDA receptors and gives dissociation with analgesia. Dexmedetomidine stimulates alpha-2 receptors.

Pharmacokinetics. Intravenous midazolam acts in 2 to 3 minutes and lasts 30 to 60 minutes. Intramuscular midazolam acts in 5 to 15 minutes. Haloperidol and olanzapine act in 15 to 30 minutes. Ketamine acts in 1 to 2 minutes intravenously and 5 minutes intramuscularly.

Rapid tranquillisation sequence. Offer oral medication first (lorazepam 1 to 2 mg or an antipsychotic). If refused or ineffective, use intramuscular midazolam or haloperidol with promethazine 25 to 50 mg to reduce dystonia. Avoid combining multiple sedatives early.

Alcohol withdrawal. Diazepam 10 to 20 mg every 1 to 2 hours, with thiamine.

Procedural sedation. Give analgesia with sedation, use a monitoring nurse and keep airway equipment and reversal agents ready.

• First-line. De-escalation, then oral or intramuscular benzodiazepine or antipsychotic; midazolam for seizures and procedures.
• Alternative. Droperidol or olanzapine alone; ketamine for severe agitation in prehospital care.
• Specialist. Dexmedetomidine and propofol sedation in intensive care; electroconvulsive therapy anaesthesia.
• Emergency. Violent or severely agitated patients, status epilepticus, alcohol withdrawal, painful procedures.

Selection. Treat hypoglycaemia, hypoxia and pain first. Use the lowest dose and the oral route if possible. Avoid antipsychotics in suspected stimulant overdose with hyperthermia unless benzodiazepines fail.

Contraindications. Benzodiazepines: severe respiratory depression, sleep apnoea (caution). Antipsychotics: QT prolongation, Parkinson disease, neuroleptic malignant syndrome. Ketamine: severe hypertension, psychosis (relative). Propofol: haemodynamic instability.

Serious adverse effects.

• Respiratory depression and airway obstruction; hypotension.
• QT prolongation and torsades (haloperidol, droperidol); acute dystonia; neuroleptic malignant syndrome.
• Laryngospasm, emergence reactions and raised pressure (ketamine); bradycardia (dexmedetomidine).
• Paradoxical agitation with benzodiazepines; delirium.

Major interactions. Alcohol, opioids and other sedatives add to respiratory depression; macrolides, quinolones and ondansetron add QT prolongation; CYP3A4 inhibitors raise midazolam levels; lithium with haloperidol.

Common prescribing errors.

• Skipping de-escalation and looking for causes.
• Giving large boluses without monitoring.
• Combining an intramuscular benzodiazepine and olanzapine.
• Giving flumazenil in benzodiazepine dependence or mixed overdose.
• Forgetting to monitor after sedation.

Special groups.

• Pregnancy: use haloperidol or low-dose benzodiazepine if needed; left tilt.
• Breastfeeding: single doses acceptable.
• Children: weight-based doses; specialist input; ketamine or midazolam for procedures.
• Older adults: halve doses, avoid antipsychotics in dementia unless dangerous.
• Kidney: reduce midazolam in severe impairment.
• Liver: reduce doses; benzodiazepines may precipitate encephalopathy.
• East Africa: diazepam, haloperidol and chlorpromazine are widely stocked, while droperidol, olanzapine injection and dexmedetomidine may not be; ketamine is widely used; ensure oxygen, suction and bag-mask devices are at hand.

Monitoring. Oxygen saturation, respiratory rate, blood pressure, level of consciousness and ECG for QT after antipsychotics, continued for at least 1 hour.

Referral and escalation. Airway compromise, apnoea, hypotension, QT over 500 ms, persistent agitation despite two agents, or suspected organic cause.

Comparison with alternative classes. Benzodiazepines act fast and treat seizures and withdrawal but depress breathing. Antipsychotics suit psychosis but prolong QT. Ketamine is quick and keeps breathing but needs skilled monitoring.