Etomidate and RSI: How important is post-intubation hypotension?

Letters

CJEM 2007;9(1):3-4

To the editor: In a recent issue of CJEM, Zed and colleagues1 and also Sivilotti2 outlined the controversy surrounding the use of etomidate for emergent endotracheal intubations. At the root of this matter is the relevance of post-intubation hypotension (PIH). It is thought that etomidate use results in less PIH than other sedatives used in rapid sequence intubations (RSIs), such as propofol and thiopental. Unfortunately, although there may be short-term gain by avoiding PIH with the use of etomidate, there may also be delayed effects by causing relative adrenal suppression.

I congratulate the authors, as this is likely an important issue. However, I disagree with the suggestion by Sivilotti2 that inducing PIH may be "beneficial, signalling marginal hemodynamic reserve (cryptic shock) well before a central line is inserted...". Few would agree that inducing hypotension in critically ill patients would have any benefit; rather, it is likely the opposite.3 Although PIH has received relatively little attention in the literature, preliminary results from Halifax indicate that it is common and may have a significant effect on patient outcomes.4,5 When 218 consecutive emergency department (ED) intubations were reviewed, the incidence of PIH was found to be 60.9%. In addition, patients with PIH required significantly more invasive procedures and an additional 8 days in hospital (9.0 v. 17.4 d). Although these data require further examination and may only describe an epiphenomenon, they highlight the potential importance of PIH.

I would also caution against the insertion of central lines and the measurement of central venous pressure (CVP) for the diagnosis of hemodynamic reserve. Central venous access is appropriate for the infusion of vasopressor or inotropic medications, and in some instances, volume resuscitation. Unfortunately, a single measurement of CVP is unlikely to provide reliable, treatment-modifying information in an acutely ill patent. I would advise against using CVP measurement as the sole determinant in the decision for or against volume expansion, and would suggest that this decision be guided by combining other variables, such as patient presentation, comorbidities, vital signs, investigations and clinical course.

Sedative medications used in RSI should be tailored to a patient's condition and physiologic needs. Do we need etomidate? I have not been convinced, as illustrated in the fact that I have only personally used it twice in the last 4 years, which includes approximately 5–15 intubations per month between the ED and the intensive care unit. But, avoiding post-intubation hemodynamic instability makes sense on many levels, and should be a priority. Other medications are available, and their use at doses that minimize PIH should be at least considered until the relevance of etomidate-associated adrenal insufficiency is better clarified.

Rob Green, BSc, MD, DABEM
Assistant Professor
Dalhousie University
Department of Emergency Medicine
Department of Medicine
Division of Critical Care Medicine
Chair, CAEP Critical Care Committee

References

1. Zed PJ, Mabasa VH, Slavik RS, et al. Etomidate for rapid sequence intubation in the emergency department: Is adrenal suppression a concern? [editorial]. Can J Emerg Med 2006;8(5):347-50.
2. Sivilotti MLA. You need tube, me give one amp of etomidate and SUX [editorial]. Can J Emerg Med 2006;8(5):351-3.
3. Jones AE, Yiannibas V, Johnson C, et al. Emergency department hypotension predicts sudden unexpected in-hospital mortality: a prospective cohort study. Chest 2006;130:941-6.
4. Edwards JP, Green RS. Post intubation hypotension: incidence, risk factors and outcomes [abstract]. Can J Emerg Med 2006;8(3):210.
5. Edwards JP, Green RS. Severe hypotension following endotracheal intubation [abstract]. Can J Emerg Med 2006;8(3):210-1.