Optimal temperature management during cardiopulmonary bypass (CPB) remains uncertain in coronary artery bypass grafting (CABG). A multicenter randomized trial presented at the AATS 2026 evaluated whether normothermic CPB reduces perioperative bleeding compared with mild hypothermic CPB in adults undergoing isolated on-pump CABG.

The single-blind trial enrolled adult patients undergoing isolated CABG with CPB at eight tertiary cardiac surgery centers in China between September 2023 and January 2025. Participants were randomized to normothermic CPB, targeting an oxygenator outlet temperature of 35–36°C, or mild hypothermic CPB with a target temperature of 32–33°C. The primary endpoint was moderate-to-severe perioperative bleeding.

Findings

• A total of 330 patients were included, with median age of 61 years and 83.9% men. 
  166 patients were assigned to mild hypothermic CPB and 164 to normothermic CPB.
• The primary endpoint occurred in 12.7% of patients in the mild hypothermic group and 11.7% in the normothermic group.
• The between-group difference was 0.4% (95% CI −6.6% to 7.4%), with OR 0.963 (95% CI 0.493–1.880; p=0.912).
• Distribution of UDPB bleeding severity grades did not differ significantly between groups (p=0.830).
• UDPB class 0 bleeding occurred in 78.9% of mild hypothermic patients and 81.1% of normothermic patients.
• UDPB class 3 bleeding occurred in 3.0% and 2.4% of patients, respectively.

In this multicenter randomized trial of adults undergoing isolated on-pump CABG, normothermic CPB guided by membrane oxygenator outlet temperature did not reduce moderate-to-severe perioperative bleeding compared with mild hypothermic CPB.