Cardio-pulmonary-bypass time has important independent influence on mortality and morbidity

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Abstract
OBJECTIVE: To determine the influence of cardio-pulmonary-bypass-time onhospital mortality and ICU-morbidity in isolated CABG surgery. METHODS:Between 1985 and 1994 perioperative data of 8578 consecutive CABGoperations were prospectively collected. Seven variables: gender, redo vs.primary operation, elective vs. urgent surgery, age in 4 categories, use ofIMA, number of distal anastomoses (> 4 vs. < = 4), andcardio-pulmonary-bypass-time in four categories were entered inmultivariate logistic regression analysis and odds ratios for respectivecardio-pulmonary-bypass-time-categories with regard to mortality,length-of-stay in the ICU and 8 ICU-complications were calculated.Bypass-time up to 90 min was the reference category, the other categorieswere from 1.5 to 2.5 h, 2.5 to 3.5 h, and longer than 3.5 h. RESULTS: 8337operations had complete data. Mortality and ICU- morbidity were low. Theodds ratios for mortality were 2.3 (P = 0.0094), 7.4 (P < 0.0001) and20.7 (P < 0.0001) for ascending bypass- time-categories. The odds ratiosfor prolonged ICU-stay were 1.8 (P = 0.0002), 3.3 (P < 0.0001) and 7.9(P < 0.0001) for ascending bypass- time-categories. For postoperativecomplications the same pattern was found: consequently higher odds ratiosfor longer bypass-time- categories. CONCLUSION: The highly significantcorrelation between cardio-pulmonary-bypass-time-category and theoccurrence of undesirable postoperative events is demonstrated by theconsequent rise in odds ratios. This independent influence ofcardio-pulmonary-bypass-time on outcome reflects both problems encounteredduring revascularisation and time-related influence ofcardio-pulmonary-bypass on the human body. When a predictive model wascreated, CPBT proved to be a good predictor of undesirable postoperativeevents.