From the FDA Drug Label
Hemodynamic Instability: Monitor vital signs and cardiac function during ketamine hydrochloride administration. (5.1)
When midazolam is used before other intravenous agents for induction of anesthesia, the initial dose of each agent may be significantly reduced, at times to as low as 25% of the usual initial dose of the individual agents.
The FDA drug label suggests that the dose of induction agents, such as ketamine 1 and midazolam 2, may need to be adjusted in patients with hemodynamic instability.
- For midazolam 2, the initial dose can be reduced, especially in patients with severe systemic disease or debilitation.
- The label recommends titrating the dose to the desired effect, taking into account the patient's age, clinical status, and current medications.
- However, there is no direct evidence to support a specific dose reduction for patients who are hemodynamically unstable during Rapid Sequence Intubation (RSI).
- It is essential to monitor vital signs and cardiac function during the administration of induction agents in these patients.
From the Research
Reducing the dose of induction agents during Rapid Sequence Intubation (RSI) in patients with hemodynamic instability is a recommended approach to minimize the risk of further hemodynamic deterioration, as supported by the most recent and highest quality study available 3.
Key Considerations
- The study published in 2023 in the Annals of Emergency Medicine 3 analyzed data from the National Emergency Airway Registry and found no association between the weight-based sedative dose of etomidate or ketamine and postintubation hypotension.
- However, considering the physiological basis and clinical experience, reducing the dose of induction agents is still a prudent approach to avoid exacerbating hemodynamic instability.
- For etomidate, a reduced dose of 0.15-0.2 mg/kg may be considered, while for ketamine, a dose of 0.5-1 mg/kg may be used.
- Propofol, which carries a high risk of hypotension, should be used with caution, and significantly reduced doses of 0.5-1 mg/kg may be considered instead of the standard 1.5-2.5 mg/kg.
Administration Approach
- When administering these reduced doses, it is essential to titrate to effect rather than giving the full calculated dose at once.
- This approach allows for achieving adequate sedation while minimizing hemodynamic compromise.
- The choice of induction agent and dose should be individualized based on the patient's specific condition and hemodynamic status.
Relevant Studies
- A study published in 2021 in the Air Medical Journal 4 compared the hemodynamic effects of ketamine and etomidate in prehospital RSI and found no significant difference in the incidence of hypotension between the two agents.
- A systematic review published in 2019 in Anesthesia and Analgesia 5 compared ketamine with other induction agents for RSI in trauma patients and found no significant difference in mortality, length of hospital stay, or number of blood transfusions.