Effect Of Interventions Based On PetCO2 Monitoring On The Incidence Of Hypoxemia In Patients After General Anesthesia Extubation

Background and PurposeAdverse respiratory events(AREs)are common postoperative complications for patients in the post-anesthesia care unit(PACU),and inappropriate management of postoperative hypoxemia will seriously endanger the safety of patients.Ventilation abnormalities such as respiratory depression and apnea can eventually lead to the development of hypoxemia.Conventional oxygen saturation monitoring has hysteresis,which can only identify the degree of hypoxia,but cannot monitor the ventilation function of patients.As a noninvasive and simple ventilation monitoring method,End-tidal carbon dioxide monitoring is widely used in operating rooms and intensive care units,but is not routinely used in PACU.The main purpose of this study was to evaluate the effectiveness in identifying patients with ventilation abnormalities through end-tidal carbon dioxide monitoring via an oronasal sampling tube in patients with tracheal intubation removed after general anesthesia,and to investigate whether the incidence and severity of hypoxemia can be reduced through patient intervention after abnormalities are found,thus improving the safety of patients during recovery.MethodA total of 300 patients undergoing neurosurgery,thoracoscopic surgery and laparoscopic surgery under general anesthesia with tracheal intubation at Qilu Hospital of Shandong University from November 2021 to April 2022 were recruited.277 patients completed the study process after screening,and patients were divided into two groups using a random number table:monitoring group(n=137)and control group(n=140).After surgery,patients who were not yet awake and intubated were sent to the PACU,and after the patients met the extubation indications and were extubated,patients in the control group underwent routine monitoring(ECG,noninvasive blood pressure,pulse oximetry),and patients in the monitoring group underwent additional micro-steam end-tidal carbon dioxide monitoring via an oral and nasal sampling tube.During the period between extubation and discharge from the PACU when the patient meets the criteria(Steward score≥4),adverse respiratory events such as respiratory depression or apnea detected by end-expiratory carbon dioxide monitoring and hypoxemia detected by oxygen saturation monitoring were observed.Patients who experienced these events were given certain interventions(including tapping and verbal stimulation,mask ventilation,supplemental antagonistic medications,and reintubation)to correct oxygenation and ventilation abnormalities.The primary outcome indicators of the study were the incidence of hypoxemia(defined as at least one occurrence of SpO2<90%,>15 s)and severe hypoxemia(defined as at least one occurrence of SpO2<85%,>15 s)in both groups.Secondary outcome indicators included:1.the incidence of oxygen desaturation(defined as the occurrence of SpO2 94-90%)and the minimum oxygen saturation value;2.the number of times patients experienced hypoxemia,respiratory depression and apnea and the interventions given;3.heart rate,mean arterial pressure,and pulse oximetry at the time the patient entered the PACU(T0),1 min after extubation(T1),5 min after extubation(T2),10 min(T3),15 min(T4),20 min(T5),and at the time of leaving the PACU(T6);4.The time of extubation and the observation time after extubation.In addition,the occurrence of other postoperative adverse events(e.g.,hypertension,hypotension,nausea and vomiting,pain,hypothermia,etc.)was also recorded.Result1.No statistical difference was found in the general information and surgical characteristics between the two groups(P>0.05).2.After extubation,21(15.3%,95%CI 9.2-21.4%)and 40(28.6%,95%CI 21.0-36.1%)patients in the monitoring group and control group,respectively,had at least one episode of hypoxemia,with a significant difference in the incidence of hypoxemia between the two groups(P=0.008).The incidence of severe hypoxemia was 4.4%(95%CI 0.9-7.8%)in patients in the monitoring group and 7.9%(95%CI 3.3-12.4%)in the control group,with no statistically significant difference between the two groups(P=0.228).3.The incidence of oxygen desaturation(32.8%,95%CI 24.9-40.8%vs.33.6%,95%CI 25.7-41.5%)was not found to be statistically significantly different between the two groups(P=0.898).The median minimum oxygen saturation monitored during the PACU was 95%(92%,96%)and 93%(88%,96%)for patients in the monitoring group and control group,respectively,with a statistically significant difference(P=0.002).4.The study recorded a total of 25 hypoxemic episodes in 21 patients in the monitoring group and a total of 62 hypoxemic episodes in 40 patients in the control group.A total of 87 respiratory depressions and 57 apneas were detected in 75(54.74%)patients in the monitoring group by additional end-tidal carbon dioxide monitoring.Among the interventions administered to patients,more patients in the monitoring group received motor and verbal stimulation(54.7%vs.28.6%,P<0.001).The proportion of patients on mask ventilation,additional supplemental antagonists and reintubation did not differ between the two groups.5.There was no statistical difference between the two groups in the time to extubation,the time to observation after extubation,and the comparison of heart rate,mean arterial pressure,and pulse oximetry at each time point from T0-T6(P>0.05).6.No statistically significant differences were found in the comparison of other postoperative adverse events between the two groups(P>0.05).ConclusionEnd-tidal carbon dioxide monitoring in the PACU for patients who have been extubated after general anesthesia surgery can detect abnormal ventilation events such as respiratory depression and apnea in a timely manner.After active intervention by medical and nursing staff,the incidence of postoperative hypoxemia in patients was significantly reduced,which improved the safety of patients during the awakening period of general anesthesia.