Relationship of Intraoperative SpO2 and ETCO2 Values with Postoperative Hypoxemia in Elderly Patients after Non-Cardiac Surgery

Elderly patients are at higher risk of postoperative hypoxemia due to their decreased respiratory function. The aim of this study was to investigate the relationship of intraoperative oxygen saturation (SpO2) and end-expiratory carbon dioxide (ETCO2) values with postoperative hypoxemia in elderly patients. The inclusion criteria were: 1) patients aged≥75 years; 2) underwent general anesthesia in non-cardiac surgery; 3) operative time longer than two hours; and 4) admission to the intensive care unit (ICU) following surgery performed between January and December 2019. Intraoperative SpO2 and ETCO2 values were collected every minute for the first two hours during surgery. The 253 patients were divided into two groups: SpO2≥92% and SpO2<92%. The time-weighted averages of intraoperative SpO2 and ETCO2 were used to compare differences between the two groups. The incidence of postoperative hypoxemia was 22.5%. For similar ventilator settings, patients with postoperative hypoxemia had lower intraoperative SpO2 and higher ETCO2 values. Sex, ASA classification, and intraoperative SpO2 were independent risk factors for postoperative hypoxemia. In conclusion, postoperative SpO2<92% was a frequent occurrence (> 20%) in elderly patients who underwent major non-cardiac surgery. Postoperative hypoxemia was associated with low intraoperative SpO2 and relatively higher ETCO2.