Dexmedetomidine and Outcomes of Cardiac Surgery (DOCS)

Overview

Cardiac surgery is associated with a high risk of cardiovascular and other complications. The investigators hypothesized that perioperative infusion of dexmedetomidine may reduce the incidence of complications and mortality following cardiovascular surgery.

There are about 694,000 open-heart surgeries performed in US each year. The major complication rates for valve plus coronary artery bypass graft (CABG) procedure are as high as 30.1% in Society of Thoracic Surgeons (STS) reports. Postoperative delirium, infection, acute renal failure (ARF) and major adverse cardiocerebral events (MACE) which include permanent or transient stroke, coma, perioperative myocardial infarction (MI), heart block and cardiac arrest represent the major postoperative complications. These complications translate into increased mortality and prolonged hospital stays with estimated costs exceeding $20 billion annually.6 The etiologies of these adverse events are multifactorial, but one major contributing factor is the surgical stress responses that result in increasing plasma levels of epinephrine and norepinephrine, with consequent myocardial oxygen supply demand imbalance and myocardial ischemia. More than 50% of all perioperative complications are related to adverse cardiovascular events. The alpha-2 receptor agonists (clonidine, dexmedetomidine) currently used in clinical practice have many desirable effects that may provide myocardial protection including analgesia, anxiolysis, inhibition of central sympathetic outflow and reduction of systemic norepinephrine release that improve hemodynamic stability and positively affect myocardial oxygen supply and demand. The most widely studied alpha-2 agonist is clonidine, a long-acting partial agonist with an alpha-2 to alpha-1 selectivity ratio of 39:1. However, dexmedetomidine is a highly selective, shorter-acting intravenous alpha-2 agonist with an alpha-2 to alpha-1 selectivity ratio of 1300:1. Multiple studies have reported that dexmedetomidine has a protective effect on specific organs including heart, brain, kidney and lungs. In addition, dexmedetomidine has been shown to have anti-inflammatory properties decreasing mortality and attenuating plasma cytokine concentrations in laboratory animals exposed to endotoxin in a dose-dependent fashion. The investigators hypothesized that dexmedetomidine may provide myocardial, brain, renal and immune function protection for cardiovascular surgical patients. The specific aim of this study was to investigate whether the perioperative use of dexmedetomidine is associated with improved outcomes and a decreased incidence in postoperative mortality, MACE or other complications in patients undergoing open-heart surgery.

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Outcomes