[Association between intraoperative hypothermia and outcomes in neonatal patients undergoing non-cardiac surgery]

Objective: To investigate the impact of intraoperative hypothermia on postoperative outcome in neonatal patients undergoing non-cardiac surgery. Methods: The data of 1 008 neonates undergoing non-cardiac surgery in Children's Hospital, Zhejiang University School of Medicine from January 2020 to October 2022 were retrospectively collected,which included 558 males and 450 females, with a midian age [M (Q₁, Q₃)] of 6 (2, 14) days. Neonates were divided into 4 groups according to whether hypothermia (below 36 ℃) occurred and the lowest body temperature during the surgery: normal temperature group (n=246), mild hypothermia group (the lowest temperature ranged 35.0-35.9 ℃, n=434), moderate hypothermia group (the lowest temperature ranged 34.0-34.9 ℃, n=232) and severe hypothermia group (the lowest temperature<34 ℃, n=96). The primary outcome was the incidence of intraoperative hypothermia. The four groups' difference of postoperative hospital stay, postoperative mortality within 30 days, postoperative pulmonary complications, postoperative hemorrhage/blood transfusion and acidosis were compared. Multivariate logistic regression was used to analyze the relationship between intraoperative hypothermia and prolonged postoperative hospital stay (>14 d), 30 d-mortality and other complications. Results: In the 1 008 neonatal patients, 762 (75.6%) cases suffered intraoperative hypothermia, among which the incidence of mild, moderate and severe hypothermia was 43.1% (434/1008), 23.0% (232/1008) and 9.5% (96/1008), respectively. The postoperative hospital stay in normal, mild, moderate and severe hypothermia groups was 9.0 (5.8, 18.0), 12.0 (7.0, 21.0), 17.0 (10.0, 34.5) and 31.5 (12.5, 55.8) days. The mortality rate with 30 days after surgery was 2.9% (7/246), 4.4% (19/434), 6.9% (16/232) and 14.7% (14/96), the incidence of postoperative pulmonary complications was 31.7%(78/246), 39.9%(173/434), 44.8%(104/232) and 67.4%(64/96), the rate of postoperative hemorrhage/blood transfusion was 19.9%(49/246), 32.3%(140/434), 49.1%(114/232) and 79.0%(75/96), and the incidence of acidosis was 26.8%(66/246), 35.7%(155/434), 44.4%(103/232) and 46.3%(44/96), respectively. All differences were statistically significant (all P<0.05). According to the adjusted logistic regression analysis, compared with the normal body temperature group, severe hypothermia was associated with prolonged postoperative hospital stay (OR=1.962, 95%CI: 1.063-3.619) and postoperative pulmonary complications (OR=2.020, 95%CI: 1.149-3.553). The mild, moderate and severe hypothermia group could increase the risk of postoperative blood/transfusion rate (mild: OR=1.690, 95%CI: 1.080-2.644; Moderate: OR=2.382, 95%CI: 1.444-3.927; Severe: OR=8.334, 95%CI: 3.123-8.929). The mild and moderate hypothermia could raise the risk of acidosis (mild: OR=1.458, 95%CI: 1.009-2.107; Moderate: OR=1.949, 95%CI: 1.279-2.972). Conclusion: Intraoperative hypothermia can prolong the postoperative hospital stay, and increase the risk of postoperative mortality, postoperative pulmonary complications, postoperative hemorrhage/transfusion, and acidosis.