What are the recommended dosages of etomidate and succinylcholine (Succinylcholine) in milligrams per kilogram (mg/kg) for Rapid Sequence Intubation (RSI) in an adult or pediatric patient?

Rapid Sequence Intubation: Etomidate and Succinylcholine Dosing

Standard Dosing Recommendations

For RSI, administer etomidate 0.3 mg/kg IV followed immediately by succinylcholine 1-2 mg/kg IV (1.5 mg/kg for infants <6 months). 1, 2, 3

Etomidate Dosing

• Standard dose: 0.3 mg/kg IV administered as a single bolus over 30-60 seconds 2, 3, 4
• This dose provides optimal sedation while maintaining hemodynamic stability in critically ill patients 2, 3
• Dose range: 0.2-0.3 mg/kg is acceptable, but 0.3 mg/kg is preferred for RSI 2, 4
• In hemodynamically compromised patients, consider reducing to 0.15-0.2 mg/kg to minimize cardiovascular effects 2

Succinylcholine Dosing

• Standard IV dose: 1-2 mg/kg (use 2 mg/kg for infants <6 months) 1
• Intramuscular dose: 4 mg/kg (5 mg/kg for infants <6 months) if IV access unavailable 1
• Dose based on actual body weight, not ideal body weight 2
• Onset of action: 30-45 seconds IV, 3-5 minutes IM 1
• Duration of action: 5-10 minutes 1

Critical Timing and Sequence

The sedative-hypnotic agent (etomidate) MUST be administered before the neuromuscular blocking agent (succinylcholine) to prevent awareness during paralysis. 2, 3

• Administer etomidate first as a single IV bolus 3
• Immediately follow with succinylcholine as early as practical after induction to minimize apnea time 2
• Wait 30-45 seconds after succinylcholine administration before attempting intubation 1

Essential Premedication

Administer atropine 0.02 mg/kg (minimum 0.1 mg, maximum 1 mg) before succinylcholine to prevent bradycardia or asystole. 1

• This is particularly important in pediatric patients 1
• In patients with increased intracranial pressure, consider a defasciculation dose of vecuronium 0.01 mg/kg before succinylcholine 1

Critical Contraindications to Succinylcholine

Do NOT use succinylcholine in patients with: 1

• Previous history of malignant hyperthermia
• Severe burns or crush injury
• Spinal cord injury
• Neuromuscular disease or myopathy
• Risk of hyperkalemia (particularly in boys <9 years old)

In these cases, use rocuronium 1.0-1.2 mg/kg IV instead 2, 3

Dosing Pitfalls to Avoid

Etomidate Under-Dosing

• Patients weighing ≥100 kg are at high risk for under-dosing 5
• 68% of patients ≥100 kg received inadequate doses (<0.2 mg/kg) in one study 5
• Always calculate the dose based on actual body weight and verify the total mg dose 5

Etomidate Over-Dosing

• Do NOT exceed 0.3 mg/kg as higher doses increase respiratory depression risk without improving intubating conditions 2, 4
• Doses ≥0.23 mg/kg in patients >55 years were associated with oxygen desaturation requiring bag-assisted ventilation 1, 4

Succinylcholine Dosing Errors

• Use actual body weight, not ideal body weight for dosing calculation 2
• Ensure adequate dose (minimum 1 mg/kg) to achieve complete paralysis and prevent patient movement during intubation 1

Pediatric-Specific Considerations

• Etomidate dose: 0.2-0.3 mg/kg IV (same as adults) 4
• Succinylcholine dose: 2 mg/kg IV for infants <6 months, 1-2 mg/kg for older children 1
• Always premedicate with atropine 0.02 mg/kg to prevent bradycardia 1
• In septic shock, strongly consider ketamine (1-2 mg/kg) instead of etomidate due to adrenal suppression concerns 2

Safety Monitoring Requirements

Have immediately available: 1, 3

• Vasopressors for hypotension management
• Bag-valve-mask for ventilatory support
• Suction equipment
• Age-appropriate intubation equipment
• Continuous pulse oximetry and cardiac monitoring

Adrenal Suppression Controversy

• Etomidate causes transient adrenal suppression, but corticosteroid administration following etomidate is NOT recommended 2
• No mortality difference has been demonstrated between etomidate and other induction agents in critically ill adults 2, 3
• However, avoid etomidate in pediatric septic shock—use ketamine instead 2