Cerebral Desaturation During Single-Lung Ventilation Is Negatively Correlated With Preoperative Respiratory Functions

ObjectivesTo evaluate the percent change of cerebral oxygen saturation (SctO2) during single-lung ventilation (SLV) and its correlation with preoperative respiratory functions.DesignA prospective, observational study.SettingClinical hospital.ParticipantsForty patients scheduled for pulmonary lobectomy requiring one-lung ventilation for at least 1 hour under combined epidural/general anesthesia.InterventionsNone.Measurements and Main ResultsSctO2 was measured using an INVOS 5100 (Somanetics Corp, Troy, MI) before anesthesia (baseline value) and until SLV was completed. In addition, arterial blood gases (ABGs) were measured every 30 minutes. The minimum SctO2 value during SLV was recorded and percent change from baseline calculated. The correlations with preoperative respiratory function (percent volume capacity [%VC], and percent forced expiratory volume in 1 second [FEV1]) and preoperative ABG levels (PaO2 and PaCO2) were examined using the Pearson correlation coefficient. The level of statistical significance was set at p < 0.05. In 28 patients (70%), the minimum SctO2 during SLV was lower than the baseline value (baseline SctO2, 69.0% ± 9.12%; range, 53%-80%; median = 71%; minimum SctO2, 66.6% ± 10.5%; range, 46%-89%; median, 67.5%). The percent change from baseline SctO2 was −4.68% ± 13.5% (−21% to 32%; median, 3.5%) and was significantly negatively correlated with preoperative respiratory function (FEV1: r = −0.482, p < 0.05; VC: r = −0.518, p < 0.05) and preoperative arterial blood PaO2 (r = −0.351, p < 0.05).ConclusionsGreater decreases were found in SctO2 during SLV in patients with better preoperative respiratory function. These findings suggest that intraoperative monitoring during SLV should include not only measurement of SpO2 and PaO2 but also SctO2.