To evaluate the roles of intraoperative changes in plasma osmolarity and pump time as predictor factors on postoperative hemodynamic instability and mid-term clinical outcomes, in adults undergoing cardiovascular surgeries with cardiopulmonary bypass.

This observational study included 172 adults undergoing cardiovascular surgery with cardiopulmonary bypass. Intraoperative changes in calculated plasma osmolarity were calculated from biochemical analyses of venous blood samples. Outcomes included the requirement for vasoactive drugs 24 hours postoperatively and mortality at 2 years. Multivariate logistic regression models adjusted for EuroSCORE II were used to analyze the data.

Both changes in calculated plasma osmolarity (OR = 1.78; 95% CI 1.18–2.27; p = .0074) and pump time (OR = 1.18; 95% CI 1.05–1.35; p = .0090) were independently associated with higher odds of requiring vasoactive drugs 24 hours postoperatively. At 2 years, changes in calculated plasma osmolarity (OR = 1.99, 95% CI 1.15–3.42; p = .0114) were associated with the combined outcome of death, hospitalization, and/or repeat cardiovascular surgery, independently of pump time (OR = 1.01; 95% CI 0.98–1.03; p = .2340), but not to mortality alone.

Changes in plasma osmolarity and pump time during cardiopulmonary bypass were associated with postoperative hemodynamic instability. Additionally, changes in plasma osmolarity were associated with adverse outcomes at 2 years.