From the Guidelines
For patients with severe hemodynamic instability requiring rapid sequence intubation (RSI), etomidate (0.2-0.3 mg/kg IV) is generally considered the safest induction agent due to its minimal cardiovascular effects, as suggested by the Society of Critical Care Medicine clinical practice guidelines 1.
Key Considerations
- Ketamine (1-2 mg/kg IV) is also an excellent choice as it provides sympathetic stimulation that can help maintain blood pressure 1.
- For neuromuscular blockade, rocuronium (1-1.2 mg/kg IV) is preferred over succinylcholine in unstable patients, especially those with hyperkalemia risk, burns, or crush injuries 1.
- Reduced doses of these medications may be necessary in profoundly unstable patients.
- Consider using fentanyl (1-3 mcg/kg IV) as a pre-treatment to blunt sympathetic response to laryngoscopy.
- Phenylephrine (50-200 mcg IV push) or norepinephrine infusion should be immediately available to treat post-induction hypotension.
- Fluid boluses should be administered before induction when possible.
Rationale
The key physiologic principle is that standard RSI doses can cause significant vasodilation and myocardial depression, potentially worsening shock in hemodynamically compromised patients, so medication selection and dosing must be carefully tailored to the patient's cardiovascular status 1.
Medication Selection
- Etomidate and ketamine are considered safe options for RSI in hemodynamically unstable patients, with no significant difference in mortality or incidence of hypotension between the two 1.
- Rocuronium is preferred over succinylcholine due to its faster onset and shorter duration of action, reducing the risk of hyperkalemia and other complications 1.
From the FDA Drug Label
In one clinical study, 10 patients with clinically significant cardiovascular disease undergoing coronary artery bypass graft received an initial dose of 0.6 mg/kg rocuronium bromide. The recommended initial dose of rocuronium bromide injection is 0.6 mg/kg; however, a lower dose of 0.45 mg/kg may be used depending on anesthetic technique and the age of the patient.
The safest Rapid Sequence Intubation (RSI) drugs for a patient with severe hemodynamic instability are not explicitly stated in the provided drug labels. However, based on the available information, rocuronium at a dose of 0.6 mg/kg or 0.45 mg/kg may be considered for RSI in patients with severe hemodynamic instability, as it has been used in patients with clinically significant cardiovascular disease.
- Key considerations:
- Dosing should be individualized and guided by the patient's clinical response.
- The use of a peripheral nerve stimulator is recommended to monitor the effect of the drug and adjust the dose as needed.
- Patients with severe hemodynamic instability may require closer monitoring and more cautious dosing due to the potential for exaggerated hypotensive effects 2.
From the Research
Safest RSI Drugs for Severely Haemodynamically Unstable Patients
The choice of Rapid Sequence Intubation (RSI) drugs for patients with severe hemodynamic instability is critical. Several studies have investigated the safety and efficacy of various RSI drugs in this context.
- Etomidate is a commonly used induction agent for RSI, known for its favorable hemodynamic profile 3, 4, 5, 6. It has a rapid onset of action and is relatively free of hemodynamic adverse effects, making it a suitable choice for patients with severe hemodynamic instability.
- Rocuronium is a neuromuscular blocking agent that can be used in combination with etomidate for RSI 3. It has a rapid onset of action and can produce optimal intubating conditions without serious complications.
- Ketamine is another induction agent that has been studied for use in RSI, particularly in the prehospital setting 7. It has been shown to have neutral hemodynamic effects and may be a suitable alternative to etomidate in certain situations.
Hemodynamic Effects of RSI Drugs
The hemodynamic effects of RSI drugs are a critical consideration in patients with severe hemodynamic instability. Studies have shown that:
- Etomidate is associated with hemodynamic stability, even in patients with low pre-RSI blood pressure 4, 5.
- Ketamine has been shown to have no significant difference in hemodynamic effects compared to etomidate in prehospital RSI 7.
- Rocuronium has been shown to be free of serious hemodynamic adverse effects when used in combination with etomidate for RSI 3.
Adrenocortical Effects of Etomidate
Etomidate has been shown to suppress adrenal function, which may be a concern in patients with septic shock or other critical illnesses 3, 6. However, the clinical significance of this effect is still unclear, and more studies are needed to fully understand the implications of etomidate use in this context.