Time-dose response of oxygen delivery during cardiopulmonary bypass in mitral valve surgery: does surgical approach matter?

IntroductionIncreased time-dose-response (TDR) of suboptimal oxygen delivery (DO) during cardiopulmonary bypass (CPB) has been associated with increased postoperative complications. The impact of surgical approach - minimally invasive vs. median sternotomy - on TDR during mitral valve surgery has not been studied.MethodsAll patients that underwent isolated mitral valve surgery at our institution between 05/2018-06/2024 were included. Perfusion variables were collected continuously (second-to-second) during CPB with a threshold of DO index <300 mL O/min/m (DOi) to quantify depth and duration of insufficient oxygen supply. The primary outcomes used for analysis were maximum and total TDR of DOi. Logistic regression was used to assess the relationship of TDR with surgical outcomes.ResultsA median sternotomy and right minithoracotomy was performed in 377 (84.1%) and 74 (15.9%) patients, respectively. The maximum and total cross-clamp (XC) TDR of DOi (577.7 vs. 91.7 AUC<300 mL O/min/m, <0.0001; 1116.0 vs. 143.1 AUC<300 mL O/min/m, <0.0001) and post-XC TDR of DOi (472.4 vs. 281.0 AUC<300 mL O/min/m, =0.0004; 606.5 vs. 334.4 AUC<300 mL O/min/m, <0.0001) were significantly higher with a right minithoracotomy. Total post-XC TDR of DOi was independently associated with postoperative AKI (OR: 1.271, CI: 1.01-1.6, =0.0413).ConclusionsA right minithoracotomy approach was associated with an increased TDR of DOi. Post-XC TDR of DOi was independently associated with postoperative AKI. These findings highlight the importance of goal-directed-perfusion and the pivotal role of perfusionists in minimally invasive mitral valve surgery.