The Effect Of Recruitment Maneuver With Inspired Oxygen Fraction Of 40% Before Extubation On Pulmonary Complications After Lung Surgery

Research background and purpose:The incidence of postoperative pulmonary complications（PPCs）after thoracic surgery is high.Lung protective ventilation strategies can reduce PPCs.Atelectasis is very common after general anesthesia.Alveolar recruitment maneuver（ARM）can reduce atelectasis,but the beneficial effect is diminished under high inspired oxygen fraction（Fi O₂）.In this study,Fi O₂ of 1.0 and Fi O₂ of 0.4 were used to perform ARM before extubation in patients undergoing thoracic pulmonary surgery,and the effects of different Fi O₂ on postoperative pulmonary complications and postoperative atelectasis were observed.Materials and Methods:According to the inclusion and exclusion criteria,a total of 120 patients undergoing thoracoscopic lung surgery were selected and randomly divided into two groups:control group C and experimental group L:Group C（n=60）was treated with ARM before extubation with Fi O₂ of 1.0,and group L（n=60）was treated with ARM before extubation with Fi O₂ of 0.4.Pulmonary protective ventilation strategies were adopted in all patients during the operation.The ventilatory tidal volume of two-lung ventilation was 6-8ml/kg,the ventilatory tidal volume of one-lung ventilation was 5-6ml/kg,and the positive end-expiratory pressure was 5 cm H₂O.Before extubation at the end of the surgery,ARM was performed with Fi O₂ of 1.0 and 0.4 respectively.Heart rate,blood pressure and oxygen saturation were recorded before anesthesia（T1）,before extubation after ARM with different Fi O₂（T2）,immediately after extubation（T3）,and 30 minutes after extubation（T4）.Arterial blood samples were collected before anesthesia（T1）,before extubation after ARM with different Fi O₂（T2）,and 30 minutes after extubation（T4）for blood gas analysis.Lung ultrasound scores（LUS）of patients before anesthesia（T1）,immediately after extubation（T3）,and one hour after extubation（T5）were recorded.Primary outcome was the incidence of PPCs in the first 7 days after surgery.Secondary and other outcomes included LUS,inflammatory factors,visual analogue scores（VAS）,postoperative nausea and vomiting,reintubation,reoperation,length of patient stay and hospital costs.Patients were followed up for death within 30 days.Results:Eight out of 120 patients were excluded for reasons including changing the thoracoscopic surgery to thoracotomy,bilateral lung surgery and intraoperative bleeding exceeding 500 ml.The final group C included 55 patients and Group L included 57patients.The baseline characteristics and intraoperative conditions of the two groups were similar,and the difference was no statistically significant（P>0.05）.After ARM with different Fi O₂,oxygen saturation（Sp O₂）and Pa O₂ in group L were lower than group C,the difference was statistically significant（P<0.01）.In group C,18 patients（18/55,32.7%）developed PPCs within 7 days after surgery,including 11 patients with respiratory failure（11/55,20%）,5 patients with respiratory infection（5/55,9.1%）,5 patients with atelectasis（5/55,9.1%）.3 patients developed two PPCs.In group L,13 patients（13/57,22.8%）developed PPCs within 7 days,including 4 patients（4/57,7.0%）with respiratory failure,7 patients（7/57,12.3%）with respiratory infection and 3 patients with atelectasis（3/57,3.5%）.There was no statistically significant difference in the incidence of PPCs within 7 days after surgery between the two groups（P>0.05）.The incidence of respiratory failure in the group L was lower than group C.The difference was statistically significant（P<0.05）.LUS of group L was lower than group C in T3 and T5.LUS in T3and T5 were higher than those before anesthesia.LUS in T5 was higher than it in T3.The difference was statistically significant（P<0.01）.There was no statistically significant difference in other secondary outcomes（P>0.05）.None of the patients died within 30days after surgery.Conclusions:In patients undergoing thoracoscopic lung surgery,the incidence of PPCs after ARM with Fi O₂ of 0.4 before extubation was similar to that with Fi O₂ of 1.0 before extubation,but the incidence of atelectasis and respiratory failure were lower than those with Fi O₂ of 1.0 before extubation in the early postoperative period.