Factors Influencing Regional Cerebral Oxygen Saturation during One-lung Ventilation in Thoracic Surgery.

Abstract

Objective To identify factors influencing regional cerebral oxygen saturation (rScO2) during one-lung ventilation (OLV) in thoracic surgery. Methods Totally 33 patients with an ASA physical status of 1-3 scheduled for elective thoracic surgery with one-lung ventilation under general anesthesia were recruited. After anesthesia was induced with propofol,fentanyl/sufentanil,and rocuronium. All patients received balanced anesthesia using sevoflurane. During OLV,volume-controlled ventilation was used with a tidal volume of 6-7 ml/kg and an inspiration:expiration ratio of 1:1.5. The ventilator frequency was adjusted with a target end-tidal carbon dioxide partial pressure (PetCO2) between 35 mmHg and 45 mmHg. During the anesthesia,patients were maintained at a pulse oxygen saturation (SpO2) of>90%,systolic blood pressure (SBP) of>90 mmHg (or reducing no more than 30% of the basic values),heart rate (HR) of>50 beat/min,and hemoglobin concentration of>90 g/L. Changes of rScO2 were monitored with FORESIGHT probes by specialized researchers. Patients were classified into low rScO2 (L-rScO2) group (n=10) or high rScO2 (H-rScO2)group(n=23) according to whether the lowest intraoperative rScO2 was under 65% or 15% lower than the baseline values. We compared gender,age,body mass index (BMI),intraoperative hemoglobin level,and the values of peak airway pressure (Ppeak),SBP,PetCO2,and SpO2 when rScO2 dropped to the lowest level between these two groups. Results Statistically higher Ppeak and lower SBP were noted in the L-rScO2 group compared with H-rScO2 group (P=0.028,P=0.046). SpO2 was lower in the L-rScO2 group compared with H-rScO2 group,but the difference was not statistically significant (P=0.421). There was also no significant difference between the two groups according to age,BMI,SpO2,PetCO2,or hemoglobin level. Ppeak appeared to be a risk factor for rScO2 reduction during OLV,as shown by unconditioned Logistic regression analysis. Conclusion During OLV in thoracic surgery,Ppeak is a risk factor for rScO2 reduction.