UMEM Educational Pearls

Category: Pharmacology & Therapeutics

Title: Predicting Hemodynamic Response to Ketamine for Prehospital RSI

Keywords: ketamine, shock index, hemodynamic, prehospital, RSI (PubMed Search)

Posted: 5/3/2016 by Bryan Hayes, PharmD (Emailed: 5/7/2016) (Updated: 5/7/2016)
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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.


  1. Dewhirst E, et al. Cardiac arrest following ketamine administration for rapid sequence intubation. J Intensive Care Med 2013;28(6):375-9. [PMID 22644454]
  2. 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]

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