Risk factors associated with surgical reintervention in postoperative cardiac surgery: is there an impact of intraoperative fluid balance?

Introduction The relationship between intraoperative fluid balance and surgical reintervention in patients undergoing cardiac
surgery is currently unclear.
Methods Case‒control study nested in a historical cohort. Patients over 18 years of age in the immediate postoperative
period of cardiac surgery were included, and unplanned surgical reintervention was evaluated as the primary outcome. Four
groups were created according to intraoperative fluid balance. We performed a univariate analysis comparing patients who
underwent reintervention (cases) with those who did not (controls), and a multivariate conditional logistic regression model
controlling for multiple confusion variables.
Results In total, 304 patients were analyzed (76 cases and 228 controls). The median age was 67 years, and the European
System for Cardiac Operative Risk Evaluation (EuroSCORE) II was greater in cases than in controls (2.05 (1.21–3.48) vs.
2.5 (1.46–4.63), p = 0.016). A greater proportion of smokers were found in cases (36.8% vs. 15.3%, p < 0.01). No differences
were found in fluid balance between groups. Moreover, no differences were found according to the type of procedure
performed given the match. The total duration of surgery was longer in reintervened patients (median 4 h (interquartile
range (IQR) 3.66–5) vs. 5 h (IQR 4–5.11), p = 0.04). According to multivariate analysis, no association was found between
fluid balance and the risk of requiring reintervention (odds ratio (OR) 1.03, confidence interval (CI) 0.86–1.23, p = 0.75).
However, reintervention was associated with smoking (OR 4.44; CI 2.09–9.44; p < 0.01) and total duration of the surgical
procedure (OR 1.39; CI 1.06–1.82; p < 0.01). The type of programming (urgent surgery) (OR 0.34; CI 0.16–0.74; p < 0.01)
and history of acute myocardial infarction in the last 7 days (OR 0.46; CI 0.21–0.99; p = 0.04) were more frequent in patients
who did not undergo reintervention.