Ketamine vs. Etomidate and Peri-Intubation Hypotension

Today’s pearl provides updated evidence regarding selection of sedatives for intubation in hypotensive patients.

Is ketamine the answer? Will etomidate come out ahead?

Etomidate and ketamine are the two most often used induction agents for RSI in our emergency department and likely in many others. Etomidate is frequently thought to be relatively neutral in terms of causing hypotension. On the other hand, ketamine may cause some catecholamine release leading to an anticipated increase in blood pressure. Utilizing the National Emergency Airway Registry (NEAR), a recent study tried to answer the question of which agent is associated with more hypotension in the peri-intubation setting (April 2020).

What They Did

• Patients > 14 years old from Jan 2016 to Dec 2018
• Importantly, this study only included patients who were ‘normotensive’ prior to intubation (SBP 100-139 mm Hg)
• Primary outcome was peri-intubation hypotension (SBP < 100 mm Hg)

What They Found

• 738 patients received ketamine, 6,068 received etomidate
• Important differences between the groups
  • Ketamine group more likely to have trauma as the indication for intubation, operator impression of a difficult airway, or presence of difficult airway characteristics
  • Ketamine group more likely to undergo intubation with video laryngoscopy
  • Ketamine group more likely to have suspected sepsis at the time of intubation (19.9% vs. 10.9%)
• Peri-intubation hypotension occurred in 18.3% of patients receiving ketamine and 12.4% for etomidate (aOR 1.4, 95% CI 1.2-1.7)
  • Dose was not associated with hypotension in either group

What It Means

1. It’s difficult to draw definitive conclusions from this data set, but it seems like we don’t need to prioritize ketamine over etomidate in terms of peri-intubation hypotension.
2. There is a subset of patients who may be ‘catecholamine depleted’ that won’t benefit from the ketamine-induced catecholamine release (Dewhirst 2013) and may actually become hypotensive as ketamine is a direct myocardial depressant. A high-shock index (≥ 0.9) may help predict who will have a blunted hypertensive response to ketamine (Miller 2016). A separate NEAR analysis found that etomidate may have less hypotension than ketamine in sepsis patients undergoing intubation in the ED (Mohr 2020).
3. One thing we learned during the spring 2020 COVID-surge was to prioritize early initiation of hemodynamic support before/during intubation.

Clinical Take-Home Point

Plan and prepare for peri-intubation hypotension in all patients undergoing RSI. Either etomidate or ketamine is appropriate, depending on individual patient clinical factors.

^#41