Igor Bulatov » Вс янв 07, 2007 3:36 am
CLINICAL ANESTHESIOLOGY
ISSUE: DECEMBER 2006 | VOLUME: 32:12
Mortality Risk Rises When Bypass Separation Is a Trial
Michael Vlessides
TORONTO—Patients who have difficulty separating from cardiopulmonary bypass (CBP) during cardiac surgery face significantly increased odds of death in the aftermath of the procedure, according to a database review by Canadian researchers. Future studies are needed to examine whether preventing difficult separation from bypass can improve outcomes in these patients, the investigators said.
Difficult separation has been implicated as a predictor of mortality in smaller studies, but the magnitude of its impact has not been adequately examined, said André Y. Denault, MD, Associate Professor of Anesthesiology at the Montreal Heart Institute, and leader of the research.
“Difficult separation from bypass appears to be an independent predictor of mortality,” Dr. Denault said. “Even if you have a short bypass time and you experience difficult separation from bypass, it will increase the risk of mortality in cardiac surgery. The interest of this study is that we could eventually consider difficult separation from bypass as a potential surrogate end point that we could study and for which we could compare different interventions.”
Dr. Denault and his co-investigators, who presented their findings at the 2006 annual meeting of the Canadian Anesthesiologists’ Society, analyzed a cohort of patients at two Quebec institutions. For purposes of the review, the definition of difficult separation from bypass was the use of vasoactive agents (noradrenaline >15 mcg per minute, milrinone, dobutamine, dopamine >5 mcg per minute) or an intra-aortic balloon pump or the return to CPB for hemodynamic reasons.
The first group consisted of 4,993 consecutive patients who underwent cardiac bypass at the Montreal Heart Institute between 1994 and 1999. The overall mortality rate was 3.6%. Patients who experienced difficult separation from bypass were 3.3 times more likely to die (95% confidence interval [CI], 1.9-5.6; P<0.0001) during surgery than those who did not. Other factors significantly linked to mortality included advanced age, weight, bypass duration, heart failure, re-operation, hypertension, use of preoperative vasoactive agents and duration of cross-clamping.
“In the presence of difficult separation from bypass, the mortality rate was doubled to 7.8%. Moreover, if you take those patients who needed to return to bypass for hemodynamic reasons or who required the addition of a device to wean from bypass, then the mortality rate increased to 35%.”
The second analysis, of 4,920 patients treated at the Quebec Heart & Lung Institute, yielded similar results. Difficult separation from bypass increased the risk for death by 80% (95% CI, 1.2-2.9; P =0.107). Other factors significantly associated with mortality in this group were advanced age, gender, preoperative creatinine level, heart failure, preoperative intra-aortic balloon pump, use of preoperative vasoactive agents, complex surgery and duration of CPB and cross-clamping.
“The highest odds ratio in the second group was the use of a preoperative intra-articular balloon pump, with an odds ratio of 6.6,” Dr. Denault said. “Gender was second, followed by difficult separation from bypass.”
Barry A. Finegan, MB, Chair and Professor of Anesthesiology and Pain Medicine at the University of Alberta in Edmonton, said the long-term effects of difficult separation from CPB remain unknown. “I’d be really interested in seeing what would happen over the long term if you took a matched group of patients who were difficult to separate from bypass, but survived one year,” Dr. Finegan said. “In other words, is the effect of difficult separation from bypass perioperatively related, or is it something that translates into a longer consequence?”
In fact, Dr. Denault’s group has examined long-term outcomes, with mixed results. Their study, of 199 patients found no long-term impact on mortality risk from difficult separation from bypass. “However,” he added, “when we examined the more severe form of difficult separation from bypass—those patients who required an intra-aortic balloon pump or who needed to return to CPB for hemodynamic reasons—the survival rate was only 55%.”
Based on a poster presentation (Abstract 26419) at the 2006 annual meeting of the Canadian Anesthesiologists’ Society by André Y. Denault, MD, and comments from Barry A. Finegan, MB.
