Risk factors for and predictive nomogram of postoperative hypoxaemia in elderly patients with femoral neck fractures

OBJECTIVE: To investigate the related risk factors and predictive nomogram of postoperative hypoxaemia in elderly patients with femoral neck fractures. METHODS: This study included patients aged ≥65 years who underwent surgical treatment of acute femoral neck fractures. Univariate and multivariate logistic analyses were performed to determine the incidence of and risk factors for postoperative hypoxaemia. A predictive nomogram was constructed based on the multivariable model. Using the bootstrap method, discrimination was determined by the C-index and calibration plot. RESULTS: The logistic regression analysis showed that the anaesthesia type, surgical procedure, American Society of Anesthesiologists (ASA) classification, preoperative hypoxaemia occurrence, and age were independent predictors of development of postoperative hypoxaemia. The predictive formula for hypoxaemia was established as follows: hypoxaemia=−0.8668×spinal anaesthesia (whether)+0.1162×nerve anaesthesia (whether)+1.9555×plate/screw fixation (whether)+1.4950×hip replacement (whether)+0.4883×ASA classification+1.7153×preoperative oxygenation index+0.1608×age. With the bootstrap method, the prediction curve fit well with the ideal curve, suggesting that the prediction curve constructed in this study has good predictive ability. CONCLUSIONS: Anaesthesia type, surgical procedure, ASA classification, preoperative hypoxaemia occurrence, and age were risk factors for postoperative hypoxaemia in elderly patients with femoral neck fractures. The predictive nomogram was designed for preoperative assessment of the risk of postoperative hypoxaemia by calculating the risk score.