Here we developed and validated a predictive nomogram for prolonged PACU LOS for LC patients. The predictors including sex, age, BMI, ASA grade, active smoker, gastrointestinal disease, liver disease, and cardiovascular disease were incorporated in our model. Usually, extended time spent in the PACU is both onerous to the patients and costly to the institution   . The nomogram suggested that younger (Age <65) male patients, with obesity (BMI >28 kg/m2), ASA grade Ⅰ, does not smoke, has no gastrointestinal disease, cardiovascular disease, or liver disease are 10% less likely to undergo prolonged PACU LOS. In this study, we provide a novel prediction nomogram vital in helping care providers (anesthesiologists, nurses) in PACU to identify patients with higher chances of being subjected to prolonged PACU LOS. Within institutions such as community hospitals and clinics with fewer ORs, this predictive tool is highly suitable and beneficial. It is worth noting that all predictors included in this model can be determined preoperatively.
Previously, several studies have revealed risk factors for prolonged PACU LOS in various surgical populations       . These studies suggest the need to focus on a special subset of patients as a way of reducing research bias , rather than focusing on all patients scheduled for surgery with general anesthesia . To the best of our knowledge, so far, no study has investigated the application of a nomogram to predict prolonged PACU LOS of LC patients.
Consistent with previous studies, we revealed that age is associated with prolonged PACU LOS  . The geriatric population may be associated with many postoperative complications and poor drug metabolism, in this case, longer recovery time is required after the operation. Likewise, patients with higher ASA grades are more likely to undergo prolonged PACU LOS. Also, we found that active smoking may result in longer PACU duration, which may be associated with a higher risk of respiratory complications. Elsewhere, a study by Coccolini et al.  demonstrated that LC had decreased odds for respiratory complications (such as airway obstruction and pneumonia) when compared with OC. Interestingly, we observed that patients with gastrointestinal diseases, such as chronic gastritis, gastric and duodenal ulcers, showed increased odds for prolonged PACU LOS. This is because such patients, in most cases, have electrolyte disorders, anemia, and high risk of postoperative nausea and vomiting (PONV), they should be carefully monitored, thus require longer stay in PACU . Due to the postoperative cardiovascular complications, it can strongly be suggested that cardiovascular disease is associated with prolonged PACU LOS.
On the contrary, patients who preoperatively had liver disease may be at a lower risk of extended time in PACU. This is closely linked to the use of anesthetic and anesthesia management of LC. For example, when handling the surgery patients with liver disease, drugs that are not metabolized by the liver (e.g. cisatracurium, remifentanil, and sevoflurane) are administered while the dosage of an anesthetic is reduced to protect liver function. Also, inconsistent with previous findings  , we found that higher BMI may result in a lower probability of prolonged PACU LOS. Based on our institution practice, we routinely selected short-acting anesthetics to induce general anesthesia and timely stopped drug infusion among obesity patients. A previous study revealed that the airway management device (i.e. LMA) was associated with prolonged PACU LOS , however, no statistical difference was found in this study. Moreover, Abdi et al.  reported that LMA, with less pharyngolaryngeal discomfort and pain, showed low risks for prolonged PACU LOS compared to ETI.
This study had several limitations. First, the retrospective design of this study implies that the selection bias and information bias is unavoidable. Second, the accuracy of the analysis relies on data records, storage, and retrieval from the medical system. Some factors include nonclinical and social issues, and difficult to extract from our electronic records. Therefore, other factors that may be associated with prolonged PACU LOS exist, and their exclusion may affect the discriminating ability in our model. Third, we included patients with specific surgery and anesthesia type, thus, the generalizability was uncertain for other patients with different types of surgical procedures and anesthesia. Finally, we report on a single-institution experience, therefore, this predictive nomogram for patients undergoing LC need to be further evaluated in the other institution and countries.