Major adverse events are clearly associated with a poor prognosis in infant after cardiac surgery [3–9]. As medical quality has advanced, pediatric heart centers have shifted their focus to promoting rapid recovery after surgery. Early detection of MAE in patients who are at risk remains a formidable task, but it could enable physicians to allocate additional resources towards the prevention and treatment of MAE in the high-risk population. Our study is the first to create a model that can predict the occurrence of postoperative early MAE in infants with congenital heart disease who have undergone cardiac surgery with cardiopulmonary bypass. Our findings indicated that certain factors, such as weight, aortic clamp time, postoperative 8th hour lactate, off-CPB blood glucose and postoperative 4 hours urine output, can be used to predict early major adverse events.
Weight is strongly associated with certain adverse outcomes in CHD infants[12, 13]. A low weight can be a potential indicator of a negative outcome during surgery [12]. Preoperative chronic cyanosis, congestive heart failure, and pulmonary hypertension often result in cardiac-related malnutrition due to insufficient nutrient intake [13]. After surgery, patients with low weight experienced a significant decrease in all parameters [14]. In addition, impaired gut function and limited fluid intake after surgery can further deteriorate nutritional status [15]. Mingjie et al. found that patients under 1-year-old had a higher incidence of preoperative malnutrition, leading to increased postoperative morbidity and mortality [14]. Rebecca et al. found that low weight might cause adverse short- and long-term outcomes, including increased the prevalence of postoperative complications, prolonged duration of ventilation and intensive care stay [16]. Our study also found that weight was a significant predictor of early MAE. Lower weight is associated with higher scores in the prediction model and an increased risk of early MAE. These findings highlight the significance of perioperative nutritional assessment, rehabilitation, and interventions, particularly in low weight infants.
The aortic cross-clamp used in cardiac surgery provided motionless and bloodless surgical area. However, aortic cross-clamp time has an inverse effect on postoperative outcomes [17]. Kate et al. conducted a retrospective analysis of 355 pediatric patients who underwent cardiac surgery with cardiopulmonary bypass aged less 1-year-old. They found a correlation between longer ICU stays and increased aortic cross-clamp time [18]. Matthew et al. analyzed the medical records of 221 infants and found a clear correlation between prolonged aortic cross-clamp time and an increase in postoperative complications [19]. The duration of aortic cross-clamp time emerged as the key factor in predicting early MAE in our study. Increased duration of aortic cross-clamp time is associated with a higher likelihood of experiencing major adverse events. Shultz et al. discovered that longer ACC durations were associated with more complex cardiac surgeries and extended ischemic times [20]. Myocardial injury and systemic inflammatory response after aortic cross-clamp can lead to serious early mortality and morbidity [21, 22].
Lactate is a well-investigated marker of adverse event. Perioperative hyperlactatemia was found to be linked to factors such as low cardiac output, inadequate oxygen support, and heightened metabolic demand [23]. Elevated blood lactate can predict early outcome in children after cardiac surgery with high specificity [24, 25]. In our training cohort, we observed an increase in intraoperative and postoperative lactate levels in both the MAE group and the non-MAE group. However, the increase was more pronounced in the MAE group. The highest lactate levels were observed at the off-CPB stage and started to decrease at postoperative 4th hour. An increase in intraoperative lactate level can be observed due to the use of intraoperative cardiopulmonary bypass and aortic cross-clamp. This increase may also extend into the early postoperative period [26]. Postoperative poor clinical status leads to a further increase in lactate levels[27]. In our prediction model, postoperative 8th hour lactate was the independent predictor of early MAE. We thought that postoperative 8th hour lactate level was a critical point. It is likely that survivors were able to eliminate intraoperative hyperlactatemia but those who continued to experience high lactate levels were affected by poor outcome [27].
The glucose level during cardiopulmonary bypass was found to be linked to the development of systemic inflammatory response syndrome and endocrine metabolic imbalance [28]. It was observed that many children undergoing cardiac surgery experienced intraoperative hyperglycemia, which unfortunately had a negative impact on their prognosis [29, 30]. In our study, off-CPB glucose emerged as a significant risk factor for early MAE. Studies by Gandhi et al, Yates et al, Matsumoto et al, and Zhi-Hua et al have all shown that there is a higher risk of postoperative complications with higher sugar levels [29–32]. It is important to maintain glycemic control during the CPB period in order to minimize postoperative complications [29, 30, 33]. Patients who maintained a CPB glucose level of no more than 8.1 mmol/L had a lower risk probability, as shown in a study [32]. Considering Asian origin have a higher insulin resistance [34], timely targeting age-adjusted hyperglycemia with insulin infusion could improve short outcome [35].
There are several limitations to our study. First, there was no gold standard inclusion or exclusion criteria for early MAE. The definition of early MAE come from the several previous study and consensus. Second, it is a retrospective single-center study, not a multi-center study. And internal bias and selection bias of this study is inevitable due to retrospective analysis. Third, external validity has not been verified. More multicenter large sample should be included in the future. Fourth, some potentially meaningful predictors, such as blood pressure, heart rate, body temperature, and ventilator conditions were not be assessed. Evidence-based methods to screen predictors should be used in the future. Fifth, more prospective case controlled studies are needed to further explain the association between risk factors and early MAE in infants.