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LETTER TO THE EDITOR

Dexmedetomidine and Refractory Cardiogenic Shock

Department of Anesthesiology; Mount Sinai School of Medicine; New York City, New York; gregory.fischer{at}mountsinai.org

To the Editor:

We do not believe that the evidence presented in the case report by Sichrovsky et al. is sufficient to make a clear association between the administration of dexmedetomidine and refractory cardiogenic shock.1

This patient's demise was initiated by an iatrogenic perforation of the left atrium, leading to pericardial effusion/tamponade and requiring emergent pericardiocentesis after a brief period of mechanical and pharmacological cardiopulmonary resuscitation (CPR). Pericaridal tamponade can be very challenging to diagnose and can present with numerous clinical facets.2 Even vaso-vagal reactions as the primary clinical event have been described in the literature.3 Although the bedside echocardiogram obtained after CPR initially showed normal left ventricular function, this could be a consequence of residual circulating epinephrine administered at the time of the cardiac arrest.

Although this patient did have a normal stress echocardiogram performed 2 yr previously and clinically there was certainly no reason to believe that he was not adequately prepared for this procedure, the autopsy did reveal nonobstructive coronary artery disease. Rupture of a coronary plaque as a consequence of arterial hypertension (epinephrine during CPR) and heparin reversal with protamine or microvascular sludging in the setting of polycythemia vera and extreme hypotension are much more plausible causes. Although this patient might not have been receiving treatment for his polycythemia vera, this disease has still been associated with an increased risk for myocardial infarction.4 Additionally, we're not aware of any report linking dexmedetomidine to ST segment elevations or ventricular fibrillation. Finally, why would dexmedetomidine selectively impair the left ventricle while preserving right ventricular function? Considering all of these factors, we question how the authors and editors attribute the patient's demise to dexmedetomidine rather than myocardial ischemia.

We are also concerned when allegations are raised linking a drug to potential adverse outcomes. We do agree that, if a scientific basis for concern is present, it is the obligation of medical journals to report such findings to the community. This case report, however, falls short! Surprising to us was the fact that this case report was also accompanied by an editorial.5 Although we agree that case reports can represent a good source of data that may increase understanding of how any medical intervention can provoke a rare, life threatening event, in this case, failing to consider the other possibilities explaining the patient's demise resulted in a case report/editorial more akin to sensationalism than a paper increasing understanding of the pharmacophysiology of dexmedetomidine.

In summary, other serious conditions were present which could plausibly explain this patient's demise and the authors have failed to present a clear link establishing the role of dexmedetomidine in this event.

REFERENCES

1. Sichrovsky TC, Mittal S, Steinberg JS. Dexmedetomidine sedation leading to refractory cardiogenic shock. Anesth Analg 2008;106:1784–6[Abstract/Free Full Text]
2. Spodick DH. Acute cardiac tamponade. N Engl J Med 2003;349:684–90[Free Full Text]
3. Riad M, Back S, Thangathurai D. Unusual presentation and course of acute cardiac tamponade. J Cardiothorac Vasc Anesth 2007;21:712–4[Web of Science][Medline]
4. Wu CF, Armstrong GP, Henderson RA, Ruygrok PN. Polycythaemia vera presenting as ST-elevation myocardial infarction. Heart Lung Circ 2005;14:51–3[Medline]
5. Talke PO, Maze M. Expecting the unexpected. Anesth Analg 2008;106:1605–6[Free Full Text]

This article has been cited by other articles:

				T. C. Sichrovsky, S. Mittal, and J. S. Steinberg Caution Is Necessary When Dexmedetomidine Is Used Off-Label, Especially When Combined with Other Sedatives Anesth. Analg., January 1, 2009; 108(1): 381 - 382. [Full Text] [PDF]

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