Both UFTCA and MICS are important components of ERACS. However, the implementation of UFTCA is not currently widely practiced in MICS. Since 2021, our center has been the administrator of the UFTCA under MICS, and with satisfactory results9. The study provided a validated nomogram for successful UFTCA implementation to help clinical decision-making. In this study, six independent predictors were identified and used to construct a novel nomogram for estimating UFTCA implementation. This nomogram demonstrated good AUC and calibration during internal validation. Additionally, the DCA confirmed the nomogram's clinical utility. This indicated that making intervention decisions using the predictive model was advantageous when the threshold risk ranged from 10–95%.
Studies of immediate extubation after cardiac surgery focused on neonates and children18–20. Relatively little research has been done on predictors of UFTCA administration in adults. Several studies have identified potential predictors of immediate postoperative extubation21,22, including age, body mass index (BMI), diabetes, operation types, fentanyl dose, paravertebral blockade, and intraoperative transfusion. We also searched for predictors related to the administration of FTCA under cardiac surgery23,24, such as recent acute coronary syndrome, preoperative renal function, and cardiopulmonary bypass time. By comparison, our study showed that intraoperative sufentanil and dexamethasone dose, CPB duration, pectoral muscle fascial plane blockade usage, operation types, and operation ended after 8 p.m. were independent factors for UFTCA implementation. Among these predictors, intraoperative dexamethasone dose and operation ended after 8 p.m. were rarely mentioned in previous literatures.
Dexamethasone is commonly used for its anti-inflammatory and against postoperative nausea and vomiting (PONV) effects. Glucocorticoid therapy has demonstrated significant beneficial effects on measures of alveolar-capillary membrane permeability, as well as on the mediators of inflammation and tissue repair25. A study showed that 20 mg dexamethasone applied early significantly decreased both the duration of mechanical ventilation and mortality in patients with acute lung injury26. In our right-thoracoscopic MICS procedure, the right lung needs to be deflated, which would likely lead to re-expansion lung injury. The use of dexamethasone may mitigate lung injury and reduce pulmonary complications. Moreover, dexamethasone was effective in preventing PONV27,28, reducing sore throat and hoarseness after tracheal tube removal29. These demonstrated that dexamethasone may facilitate the successful performance of UFTCA. Another important finding of this study was the influence of surgical endpoint on UFTCA implementation. There was evidence that night-time surgery may have a higher rate of postoperative complications as well as adverse events than daytime surgery30. Also, if the surgeon worked continuously from day to night, the incidence of postoperative complications would increase greatly31. This suggested that an appropriate workload could ensure the work status of the surgeon and increase the security of the patient during the hospitalization. In addition, anesthesiologists need to pay more attention to the implementation of UFTCA which may increase the anesthesiologist's workload and lead them to choose more conservative anesthetic protocols.
FTCA and UFTCA were based on administering relatively small doses of short-acting opioids, which were supplemented with either propofol or other anesthetic agents32,33. As a result, a significant reduction in sufentanil dose was an independent predictor of UFTCA implementation. However, reduction of intraoperative opioid use is controversial, because it may lead to an increased need for postoperative analgesia34,35. FPCWB was performed in UFTCA in our center to alleviate postoperative analgesia. Our previous observational study showed that the incidence of ICU rescue analgesia was lower in patients who used FPCWB than in those who did not9. Continuous deep FPCWB was shown to improve postoperative pain and reduce postoperative opioid requirements from the research of Toscano et al36. CPB duration was an independent predictor of UFTCA implementation in this study. CPB, a non-physiological circulation employed during cardiac surgery, can lead to pulmonary endothelial damage, and increased pulmonary vascular resistance. There were many studies showing that CPB duration was an independent risk factor for complications after cardiac surgery, such as renal injury and cerebral microemboli37,38. CPB duration may be correlated with the complexity of procedure. The result showed that multiple valve surgery was an independent risk factor of UFTCA implementation. Patients undergoing a single procedure are more likely to be successfully extubated than complex procedures.
This study had several limitations. First, this model is about the implementation of UFTCA in MICS and could not work for all types of cardiac surgery. Second, the preferences of anesthesiologists and surgeons for UFTCA could not be controlled during the observational period. Thirdly, this study is a retrospective analysis conducted at a single center and does not include external data validation. To confirm the model’s validity, further prospective studies across multiple centers are necessary. Driven by the progress in machine learning, a wider array of feature variable filtering approaches have been developed. Expanding the number of variables considered and applying different screening strategies can enable the construction of enhanced predictive models.