Ketamine is often thought to be the induction agent least associated with hypotension in the peri-intubation period. However, reports of hypotension following ketamine do exist, including 2 cases of cardiac arrest. [1] There are limited objective means to predict which patients may have an adverse hemodynamic response.
New Study
A new prospective observational study followed 112 patients in the prehospital setting who received ketamine for rapid sequence intubation. 81 had a low shock index [< 0.9], 31 had a high shock index. [2]
Shock index = HR / SBP
What They Found
Patients with a high shock index were more likely to experience hypotension (SBP < 90 mm Hg) in the peri-intubation period compared to those with a low shock index (26% vs 2%).
Application to Clinical Practice
- This is the first study to evaluate a potential objective predictor for which patients may experience hypotension after RSI with ketamine. But, even with a high shock index, the majority of patients did not develop hypotension.
- These findings should not lead to avoidance of ketamine in these situations, as other induction agents are equally or more likely to cause adverse hemodynamic effects.
- It has been suggested to use lower induction doses in patients at risk for hypotension (with the same or higher paralytic dose). Patients with a high pre-RSI shock index may be the population in which to consider that approach.
References
- Dewhirst E, et al. Cardiac arrest following ketamine administration for rapid sequence intubation. J Intensive Care Med 2013;28(6):375-9. [PMID 22644454]
- Miller M, et al. Hemodynamic response after rapid sequence intubation with ketamine in out-of-hospital patients at risk of shock as defined by the shock index. Ann Emerg Med. 2016 Apr 26. Epub ahead of print. [PMID 27130803]
Follow me on Twitter (@PharmERToxGuy)