In this retrospective study, multivariate logistic regression analysis demonstrated that age and duration of surgery were risk factors independently. In contrast, PCA, intraoperative intercostal nerve block, anesthetic intubation method, and sufentanil use were all independent protective factors. The five machine learning models constructed from these candidate indicators demonstrated excellent predictive efficacy in both training and validation sets; consequently, it is highly applicable to clinical settings. Moreover, accurately identifying protective and disruptive factors via these machine learning models and nomograms may reduce the incidence of PCNC and improve postoperative patients’ quality of life.
In the present study, the incidence of PCNC was approximately 20%, which was different from the results of previous studies, which focused more on severe perioperative cardiovascular and neurological complications such as perioperative acute ischemic stroke and acute myocardial infarction [2, 3]. However, cardiovascular and neurological events, such as postoperative atrial fibrillation and transient cerebral ischemia, have also been shown in previous studies to be independent risk factors for severe postoperative cardiovascular and neurological adverse events and death [4]. Therefore, our study was differentiated from previous studies by including all perioperative cardiovascular and neurological complications, regardless of severity, as outcome variables to be explored in the study and analyzed to derive independent factors affecting the outcome. The criteria for defining PCNC in this study included evidence on ECG, cranial MRI, or CT scans, findings following consultation with a cardiologist or a neurologist, and a diagnosis of new-onset cardiovascular or neurological-related diseases during the postoperative period. These inclusion criteria included almost all the additional PCNC-related diseases as observations, making the study more detailed and comprehensive.
It has been confirmed that age has a critical role as a risk indicator for PCNC [14–17]. Additionally, several studies have confirmed the duration of surgery in relation to the high postoperative complications incidence [11, 18, 19]. The findings of this study confirmed this.
With the increasing trend of opioid-free anesthesia recently, many anesthesiologists consider the opioid analgesics used in the past as unideal and possibly even counterproductive, contributing to the severity of postoperative pain and being strongly associated with adverse postoperative outcomes [20–23]. Regarding the use of opioid drugs, the existing studies demonstrate contradictory evidence [24, 25]. However, most studies examined whether focusing an investigation on opioid-related adverse outcomes such as nausea and vomiting alone [26–28] while ignoring postoperative adverse cardiovascular and neurological events may adversely affect patient survival and prognostic outcomes. In real-world practice, experienced anesthesiologists prefer to use a higher dose of sufentanil when a patient’s hemodynamic state becomes unstable. In addition, the duration of surgery is positively correlated with the incidence of PCNC; as the duration of surgery increases, the dosage of sufentanil increases, which may lead to serious bias that a higher dose of sufentanil may be related to the occurrence of PCNC. In contrast, our data analysis showed that sufentanil is an independent protective rather than a risk factor for PCNC. Hence, we are more concerned with the conclusion that the appropriate intraoperative administration of sufentanil helps improve patients’ prognosis during the early postoperative period from the anesthesiologist’s point of view. This may be because maintaining perioperative hemodynamic stability improves perioperative cardiovascular and neurological complications.
In thoracic surgical procedures, an intraoperative intercostal nerve block is an intercostal nerve block performed by thoracic surgeons under direct thoracoscopic view. Compared with the traditional intercostal nerve blocks performed under ultrasound guidance with a more defined block extent, the intercostal nerve block performed by thoracic surgeons under direct thoracoscopic view has not been fully implemented. In this study, the intraoperative intercostal nerve block was shown to be an independent protective factor and accounted for a larger predictive score in the nomogram; therefore, it has a stronger influence on the risk of PCNC. Therefore, this method can be recommended to thoracic surgeons to reduce postoperative patient pain, accelerate recovery, and reduce the incidence of PCNC.
As a standard postoperative analgesic modality used in recent years with individualized, on-demand, and self-controlled drug delivery, PCA [29] is receiving increasing attention and popularity among patients. However, postoperative patient-controlled epidural analgesia (PCEA) is associated with adverse postoperative outcomes in surgery, such as hypotension [30]. Additionally, patient-controlled intravenous analgesia (PCIA) may cause a marked increment in the incidence of nausea and vomiting in patients [31, 32]. Although the impact of PCA on PCNC is unclear, it is possible that both PCEA and PCIA are protective because PCA reduces postoperative pain. All of the above three perioperative analgesic modes exerted a significant protective effect on PCNC, thus, we hypothesized that by alleviating perioperative pain, the aim of maintaining stable perioperative hemodynamics and improving perioperative cardiovascular and neurological complications could be achieved [33].
Achieving lung separation in thoracic surgery primarily involves using double-lumen endobronchial tubes (DLTs) or bronchial blockers (BBs). DLTs can be easily and precisely inserted, while BBs can reduce the incidence and degree of airway injuries [34, 35]. However, no studies have investigated the association between the intubation method and PCNC. The present study confirmed that BB is more protective in reducing the risk of PCNC compared with DLT. In contrast to the results of previous studies, we hypothesize that the inflammatory response due to more severe airway injury caused by DLT may be responsible for the higher susceptibility to PCNC [35]. Outcomes after VATS pneumonectomy are comparable to open approaches.
While this study developed machine learning models and predictive nomograms for PCNC, it has limitations. A relatively minor sample size was included in the current study. The inclusion of more patients in future studies will reduce bias and increase the accuracy and effectiveness of the prediction model. In addition, in a strict sense, the training and validation sets established in this study cannot be called external validation sets. Hence, multi-center studies are warranted to fill this gap.