The RAMER Reviews: Postintubation Hypotension Following Rapid Sequence Intubation with Full- vs Reduced-dose Induction Agent
Written by Jaron Kurian, MD; Edited by Timothy Khowong, MD, MSEd
Background
Rapid sequence intubation (RSI) is a common emergency department (ED) procedure with an associated complication of postintubation hypotension (PIH). It has not been clearly established whether the selection and dose of induction agent affect risk of PIH. The objective of this study was to determine the incidence of PIH in patients receiving full-dose compared to reduced-dose induction agents for RSI in the ED.
The Study
This study examined whether the dose of induction agents used during rapid sequence intubation (RSI) in the emergency department affects the incidence of postintubation hypotension (PIH), defined as a systolic BP drop to less than 100 mm Hg or a 20% decrease from baseline. The retrospective, single-center study reviewed 909 patient records, comparing outcomes for those who received full-dose versus reduced-dose etomidate or ketamine. The majority of patients (84%) received etomidate, while 16% received ketamine. The study found that patients given full-dose ketamine had the lowest pre-intubation blood pressure and a higher pre-intubation shock index, suggesting poorer baseline hemodynamics compared to those who received etomidate.
The results showed that full-dose ketamine was associated with the highest rate of PIH (36.5%), significantly more than reduced-dose ketamine (16.7%) and full-dose etomidate (22.8%). Interestingly, reducing the ketamine dose appeared to decrease the incidence of PIH, suggesting that dose adjustment could mitigate hypotension risk with this agent. However, there was no significant difference between full and reduced doses of etomidate in terms of PIH. The study did not conduct a formal power analysis, so while the sample size was substantial, it's unclear if the study was adequately powered to detect specific differences between dosing regimens. Baseline differences, such as the higher shock index in ketamine recipients, could be confounding factors that influenced the results.
Discussion
The elevated incidence of postintubation hypotension (PIH) with full-dose ketamine (36.5%) underscores a clinically relevant issue. Notably, patients receiving full-dose ketamine in this study had poorer baseline hemodynamics, suggesting that ketamine’s effects on blood pressure could be exacerbated in those already at risk. In hemodynamically unstable patients, a reduced ketamine dose may be prudent, though creating a definitive guideline from this study is challenging due to confounding factors. Ultimately, decisions on dose adjustments should be tailored to individual patient profiles rather than applied uniformly.
The study did not explore long-term outcomes associated with PIH, such as mortality, morbidity, or length of ICU and hospital stays. This limits the clinical relevance of these findings, as there’s no direct evidence that reduced-dose strategies lead to improved patient outcomes. While the sample size of 909 helps mitigate random error, the absence of a formal power analysis raises questions about whether the study was sufficiently powered to detect true differences.
TLDR - I might use reduced doses of ketamine in hemodynamically unstable patients depending on the situation (i.e. the patient is so altered that they may not require a full dose), but this study alone does not provide enough evidence to change my general practice. There is no information on pre intubation resuscitation with IVF/Vasopressors, so maybe the patients just needed to be better optimized? We’ll see with future studies, if these dose related changes actually show any clinical significance.
References
Mattson AE, Brown CS, Sandefur B, Mara K, Haefke B, Cabrera D. Postintubation hypotension following rapid sequence intubation with full- vs reduced-dose induction agent. Am J Health Syst Pharm. Published online July 24, 2024. doi:10.1093/ajhp/zxae217