The Effects Of Positive End-expiratory Pressure On Arterial Oxygenation And Dynamic Lung Compliance During Prone Position Lumbar Spine Surgery

Objective: The aim of this study is to determine the effects of positiveend-expiratory pressure on arterial oxygenation and dynamic lung complianceduring prone position lumbar spine surgery.Method: This study included60patients, who were undergoing lumbarlaminectomy interbody fusion and internal fixation surgery in Bethune FirstHospital of Jilin University from December2012to February2013. Patientswere randomized to three groups:Group A (PEEP0cmH2O, n=20), GroupB(PEEP6cmH2O, n=20), Group C(PEEP12cmH2O, n=20) according to a tableof random numbers. In the operating room, patients were lying flat on theoperating table and standard monitoring was established. A radial arterycatheter was inserted before induction of anesthesia. After anesthesia wasinduced, endotracheal intubation was completed and the patients’ lungs wereventilated by a ventilator.The fresh gas flow was2L min, Air adjusted tomaintain inspiratory O2of50%, VT of8mL/kg, inspiratory:expiratory ratio of1:2, adjust the ventilatory rate to maintain PaCO2between35-45mmHg. Andthen turn the patient position to prone position. In Group A the PEEP wasmaintained at0cmH2O, In Group B the PEEP was maintained at6cmH2O, InGroup C the PEEP was maintained at12cmH2O throughout the end ofanesthesia. After the surgery was completed，the position of patient was turnedto supine position again. The oxygenation index （OI）, dynamic lungcompliance（Cdyn）, partial pressure of carbon dioxide in artery (PaCO2), PH,end tidal pressure of carbon dioxide（PETCO2）, peak airway pressure（Ppeak）,plateau pressure （Pplat）, mean artery pressure (MAP), heart rate (HR) were recorded at the time5min after endotracheal intubation with supineposition(T0),5min after prone position(T1),30min after prone position(T2),60min after prone position(T3),120min after prone position(T4). Partialpressure of oxygen (PaO2) and PaCO2were also nead to be recorded at the time30min after tracheal extubation (T5). Finally, medical records and clinical noteswere reviewed after hospital discharge for development of the postoperativepulmonary complications and length of hospitalization.Result:1, No significant differences have been observed among the threegroups in patients’ general characteristics.2, Patients in Group B had asignificantly higher intraoperative OI than Group A，Patients in Group C had asignificantly higher intraoperative OI than Group A and Group B. Group Bsignificantly increased Cydn than Group A from T2to T4. Group Csignificantly increased Cydn than Group A ang Group B from T2to T4.3, Pplatand Ppeak of the patients in Group B and Group C were significantly higherthan Group A.4, The patients in Group C had significantly higher HR andsignificantly lower MAP than Group A from T1to T3.5, No significantdifferences among the three groups in PaO2and PaCO2were observed at T5.Furthermore, The length of hospitalization and incidence of pulmonarycomplications were not significantly different.Conclusion:1, PEEP effectively improved intraoperative arterialoxygenation and dynamic lung compliance during prone position lumbar spinesurgery.2, PEEP12cmH2O had a more obvious emprovement of arterialoxygenation and dynamic lung compliance,but it causes evidently increasedHR and MAP.