Negative Correlation Between Body Mass Index and Chest Tube Out-put After Coronary Artery Bypass Graft Surgery
Keywords: Body mass index, obesity, bleeding, chest tube out-put, cardiac surgery, coronary artery bypass surgery
Introduction: The obvious threat of obesity to human life is well-known, but some contradictory outcomes have been encountered during previous medical research. Interestingly, obesity was recognized as a protective factor for some specific obesity-related situations. We aimed to correlate increased body mass index (BMI) and chest tube out-put after coronary artery bypass grafting (CABG). Patients and Methods: We retrospectively collected data of 421 patients who underwent isolated CABG surgery between dates of December 2015 and December 2016. Obtained BMI values were grouped into: underweight (< 20 kg/m2 ), normal weight (20-25 kg/m2 ), overweight (25-30 kg/m2 ), obese (30-35 kg/m2 ), and severely obese (> 35 kg/m2 ) subclasses. The postoperative chest tube output volume corresponded drainage at first 24 hours after the CABG surgery. Results: The mean age was 61.6 (± 1.06) years. Female to male ratio was found 40, 9/59, 6 (n= 170/251). The patient population was divided into 2 groups as BMI below and above 30 kg/m2 to approximately evaluate the relation between BMI and chest tube out-put. Overall, 193 patients were in the non-obese group, and 136 patients were in the obese group. The mean drainage amounts of non-obese and obese groups were 630 ± 360 and 463 ± 303 mL, respectively. We ran independent t-test to evaluate the relationship between BMI and chest tube out-put. It was statistically significant. The relationship between drainage and five different BMI subgroups was evaluated. Analysis of variance (ANOVA) showed statistically significant chest tube output difference between the normal and obese groups as well as the severely obese group. Conclusion: BMI is negatively correlated with bleeding after CABG surgery and should be considered in future bleeding prediction systems.