What is the best alternative for rapid sequence intubation in a patient with an aortic aneurysm when an induction agent is not available?

From the Guidelines

In a patient with an aortic aneurysm requiring emergency intubation without an induction agent, ketamine is the best alternative due to its ability to maintain hemodynamic stability. Ketamine at 1-2 mg/kg IV provides both anesthetic induction and sympathetic stimulation, which helps maintain blood pressure and cardiovascular stability—crucial in aortic aneurysm cases where hypotension must be avoided 1. This should be combined with a paralytic agent such as rocuronium (1-1.2 mg/kg) or succinylcholine (1-1.5 mg/kg) to facilitate intubation, as recommended by the Society of Critical Care Medicine clinical practice guidelines for rapid sequence intubation in the critically ill adult patient 1. If hypertension is a concern, consider adding a short-acting beta-blocker like esmolol (0.5 mg/kg) to blunt the sympathetic response during laryngoscopy. Pre-treatment with fentanyl (1-3 mcg/kg) 3 minutes before intubation can also help attenuate the hemodynamic response. Ketamine is preferred because it preserves hemodynamic stability through its sympathomimetic effects, unlike other induction agents that may cause dangerous hypotension, as suggested by the comparison of different induction agents in critically ill patients 1. Continuous hemodynamic monitoring is essential throughout the procedure, with a target systolic blood pressure that avoids both hypertension (which increases aortic wall stress) and hypotension. The choice of ketamine is further supported by its quick onset and short duration of action, as well as its preservation of respiratory drive, making it a reasonable option for RSI in critically ill patients 1.

From the FDA Drug Label

In patients in whom potentiation of, or resistance to, neuromuscular block is anticipated, a dose adjustment should be considered The recommended initial dose of rocuronium bromide injection, regardless of anesthetic technique, is 0.6 mg/kg. Neuromuscular block sufficient for intubation (80% block or greater) is attained in a median (range) time of 1 (0. 4 to 6) minute(s) and most patients have intubation completed within 2 minutes.

In a patient with an aortic aneurysm requiring emergency intubation without an induction agent, rocuronium 0.6 mg/kg can be administered to facilitate rapid sequence intubation. However, it is crucial to note that the use of rocuronium without an induction agent may not provide optimal intubating conditions, and the patient's hemodynamic status should be closely monitored.

• The dose of 0.6 mg/kg is recommended for tracheal intubation.
• Intubation can be completed within 2 minutes in most patients.
• It is essential to monitor the patient's neuromuscular function and adjust the dose as needed to avoid complications.
• The use of rocuronium in patients with aortic aneurysm should be done with caution, and the patient's condition should be closely monitored due to the potential for hemodynamic instability 2.

From the Research

Alternative Induction Agents for Rapid Sequence Intubation

In the absence of a traditional induction agent for rapid sequence intubation in a patient with an aortic aneurysm, several alternatives can be considered:

• Ketamine: According to 3, ketamine represents a rational choice for rapid sequence induction in haemodynamically compromised patients due to its favorable pharmacological properties that confer haemodynamic stability.
• Fentanyl: As discussed in 4, fentanyl could serve as an alternative induction agent for rapid sequence intubation due to its neutral hemodynamic response and fast onset of action.
• Etomidate: Although etomidate has been withdrawn from use in some countries and impairs steroidogenesis, it is still considered to have favorable pharmacological properties for rapid sequence induction, as mentioned in 3.

Considerations for Aortic Aneurysm Patients

When managing a patient with an aortic aneurysm, it is essential to consider the risk of rupture and the potential impact of induction agents on hemodynamics:

• The risk of rupture increases with the diameter of the aneurysm, as noted in 5.
• Induction agents that minimize hemodynamic instability are preferred to reduce the risk of rupture.
• Ketamine and fentanyl are potential options, as they are associated with relatively stable hemodynamics, according to 3 and 4.

Rapid Sequence Intubation Procedure

The process of rapid sequence intubation involves:

• Administration of a sedative or induction agent, as discussed in 6.
• Immediate administration of a neuromuscular blocking agent to facilitate endotracheal intubation.
• The choice of induction agent and neuromuscular blocker should be based on the patient's clinical status and the potential risks and benefits of each medication, as reviewed in 7.