What are the optimal drugs for prehospital intubation and their rationale?

Optimal Prehospital Intubation Drugs

For prehospital rapid sequence intubation in adults, use ketamine (1-2 mg/kg IV) as the induction agent followed by rocuronium (1.0-1.2 mg/kg IV) as the neuromuscular blocker, with etomidate (0.3 mg/kg IV) reserved for hemodynamically unstable patients. 1

Induction Agent Selection

Ketamine as First-Line Agent

• Ketamine (1-2 mg/kg IV) is the preferred induction agent for prehospital intubation due to its sympathomimetic properties that maintain hemodynamic stability in trauma and critically ill patients 2, 1
• The drug provides relative cardiovascular stability through catecholamine release, making it particularly valuable in the unpredictable prehospital environment 2
• Historical concerns about ketamine increasing intracranial pressure in head injury patients are of little practical significance, and the drug is now frequently used in prehospital head injury cases 2

Etomidate as Alternative

• Etomidate (0.3 mg/kg IV) serves as an alternative first-line agent, particularly in hemodynamically unstable patients, due to its minimal cardiovascular effects 1
• The Critical Care Medicine society found no mortality difference between etomidate and other induction agents in critically ill patients 1
• While etomidate causes transient adrenal suppression, corticosteroid administration following etomidate is not recommended 1

Critical Caveat for Ketamine

• In critically ill patients with depleted catecholamine stores (severe sepsis, prolonged shock), ketamine may paradoxically cause hypotension despite its sympathomimetic properties 1
• Ketamine has disadvantages when used after resuscitation from cardiac arrest or in patients with severe cardiac disease due to its sympathomimetic effects 2

Neuromuscular Blocking Agent Selection

Rocuronium as Preferred Agent

• Rocuronium (1.0-1.2 mg/kg IV) is the preferred neuromuscular blocker for prehospital RSI, providing excellent intubating conditions within 60 seconds 1, 3
• High-dose rocuronium (≥0.9 mg/kg) produces intubating conditions comparable to succinylcholine, with 99% of patients achieving excellent or good conditions 3
• The FDA label confirms that rocuronium 0.6-1.2 mg/kg provides excellent to good intubating conditions in less than 2 minutes 3

Succinylcholine as Alternative

• Succinylcholine (1-1.5 mg/kg IV) remains an alternative when no contraindications exist, though its numerous serious side effects limit its use 1
• The Critical Care Medicine society recommends succinylcholine as first-line only when no contraindications are present 1

Essential Safety Measure

• Sugammadex must be immediately available when using high-dose rocuronium (≥0.9 mg/kg) for potential reversal in a "can't intubate, can't ventilate" scenario 1, 4

Post-Intubation Sedation

Maintenance Sedation Requirements

• Most patients require a hypnotic drug (midazolam or propofol) to maintain sedation during transport after neuromuscular blockade 2
• Accidental awareness is more likely when neuromuscular blocking drugs are used, particularly in emergency patients with high pre-induction Glasgow coma scores 2
• Small, frequent doses of sedatives minimize hemodynamic side-effects and should be titrated against physiological variables 2

Timing Considerations

• Intubation with rocuronium is associated with a longer time (14.8 minutes vs 9.2 minutes) until administration of post-intubation sedation compared to succinylcholine, creating a window for awareness 5
• This delay represents a critical opportunity for improvement in sedation practices after rocuronium RSI 5

Pediatric Modifications

Atropine Pretreatment

• Atropine (0.01-0.02 mg/kg IV, maximum 0.5 mg) should be administered before intubation in children aged 28 days to 8 years, particularly with septic shock, hypovolemia, or when using succinylcholine 2, 4, 6
• This prevents bradycardia from vagal stimulation during laryngoscopy, which can cause significant hemodynamic decompensation in cardiovascularly unstable children 2

Pediatric Drug Selection

• Ketamine is the first-line induction agent for pediatric prehospital RSI, especially in hemodynamically unstable patients 4, 6
• Etomidate should be avoided in pediatric septic shock due to adrenal suppression concerns 1, 4
• Rocuronium dosing for pediatrics: 0.9-1.2 mg/kg IV when succinylcholine is contraindicated 4, 6

Critical Pitfalls to Avoid

Medication Administration Errors

• Never administer neuromuscular blockers without first ensuring adequate sedation, as this causes awareness during paralysis 2, 1
• Ensure vasopressors are immediately available before induction, as both ketamine and etomidate can cause hypotension in specific circumstances 1

Timing and Dosing Errors

• Wait at least 60 seconds after rocuronium administration before attempting intubation to ensure adequate neuromuscular blockade 1
• In obese patients, dose rocuronium based on actual body weight, not ideal body weight, as ideal body weight dosing results in inadequate intubating conditions 3

Post-Intubation Care Gaps

• Do not delay post-intubation sedation after rocuronium administration—this is a common error that increases risk of awareness 5
• Confirm correct tube placement with waveform capnography immediately and repeat each time the patient is moved 2
• Adjust ventilation to achieve normocapnia (end-tidal CO2 of 4.0-4.5 kPa) as abnormal end-tidal CO2 is associated with increased mortality 2