Association of positive fluid balance and cardiovascular complications after thoracotomy for noncancer lesions

OBJECTIVE The purpose of this study was to explore the influence of positive fluid balance on cardiovascular complications after thoracotomy for noncancer lesions. METHODS After approval from an institutional review board, a retrospective cohort study was conducted. All consecutive patients undergoing thoracotomy between January 1, 2005 and December 31, 2011 in a single medical center were recruited. The primary outcome of the study was the incidence of cardiovascular complications, which were defined as cardiac arrhythmia, cardiac arrest, heart failure, myocardial ischemia, and pulmonary embolism. Univariable and multivariable risk regression analyses were used to evaluate the association between positive fluid balance and cardiovascular complications. RESULTS A total of 720 patients were included in this study. The incidence of cardiovascular complications after thoracotomy for noncancer lesions was 6.7% (48 of 720). Patients with positive fluid balance >2,000 mL had a significantly higher incidence of cardiovascular complications than those with positive fluid balance ≤2,000 mL (22.2% versus 7.0%, P=0.005). Cardiac arrhythmias were the most common complication. Univariable risk regression showed that positive fluid balance >2,000 mL was a significant risk factor (risk ratio =3.15, 95% confident interval [CI] =1.44-6.90, P-value =0.004). After adjustment for all potential confounding variables during multivariable risk regression analysis, positive fluid balance >2,000 mL remained a strong risk factor for cardiovascular complications (risk ratio =2.18, 95% CI =1.36-3.51, P-value =0.001). Causes of positive fluid balance >2,000 mL included excessive hemorrhage (48%), hypotension without excessive hemorrhage (29.6%), and liberal fluid administration (22.4%). CONCLUSION Positive fluid balance was a significant risk factor for cardiovascular complications. Strategies to minimize positive fluid balance during surgery for patients at high risk of cardiovascular complications include preparing adequate blood and blood products, considering appropriate hemoglobin level as a transfusion trigger, and adjusting the optimal dose of local anesthetic for intraoperative thoracic epidural analgesia.