| PURPOSE:The safety of blood flow and the feasibility of fine flow management in patients with venoarterial extracorporeal membrane oxygenation（VA-ECMO）were evaluated by real-time monitoring of near-infrared spectroscopy saturation of cerebral oxygenation（NIRS-Sc O2）and sublingual microcirculation,combined with multiple parameters such as large circulation and echocardiographic.PATIENTS AND METHODS:A prospective self-controlled study was conducted on adult patients receiving VA-ECMO treatment in SICU and EICU of Sichuan Provincial People’s Hospital from December 2019 to January 2021.The NIRS-Sc O2-monitored flow regulation trial is expected to be performed on day 2（within 24-48h）and day 4（within72-96h）after VA-ECMO treatment,respectively.Two NIRS probes were placed above the eyebrow arch of patients for real-time and continuous monitoring of bilateral brain Sc O2,and 5 minutes of real-time VA-ECMO blood flow was monitored as the baseline value of NIRS（S1）.The VA-ECMO blood flow（S2）was reduced by 20%by adjusting the centrifugal pump speed based on the baseline level,then returned to the baseline value（S3）,and then increased by 20%（S4）.Each stage from S2 to S4 was maintained for 30minutes.After the end of S3 stage,the blood flow was slowly reduced to S2 level within5 minutes and maintained for 2 hours（S5）.During the preset time period of S1,S2,S4and S5,parameters of the patients’major circulation,sublingual microcirculation and cardiac ultrasound were collected.After the completion of the S5 stage,the flow will be returned to the baseline and the current flow control experiment will be ended.The dynamic changes of NIRS-Sc O2,major circulation,sublingual microcirculation and cardiac ultrasonic parameters in four different VA-ECMO flow stages（S1,S2,S4 and S5）were comprehensively analyzed.RESULTS:There were 26 patients,excluding 2 patients with mean arterial pressure（MAP）below 60mm Hg,24 patients completed the 2nd day of VA-ECMO flow control experiment;5 patients died/weaned（3/2）within 4 days after arrival,and the remaining19 patients completed the 4th day of flow control experiment.The second day of VA-ECMO support:Sc O2and VA-ECMO blood flow basically maintained a positive correlation,and the difference in different flow stages was statistically significant（P<0.01）.Using baseline VA-ECMO flow phase（S1）as a reference,the mean variation of NIRS-Sc O2in S4 and S2 phases was 2%and 0.7%,respectively,neither exceeding 5%of baseline.The mean arterial pressure（MAP）in low flow（S2）was significantly lower than that in baseline flow（S1）and high flow（S4）（P<0.01）.There was no difference in heart rate,arterial blood lactic acid and microcirculation in the four stages.The aortic outflow tract velocity-time integral(VTIAV)at S2 and S5 stages were significantly higher than those at S1 and S4 stages（P<0.001）.Day 4 supported by VA-ECMO:the difference of brain Sc O2 on both sides was smaller than that on day 2,and the mean NIRS-Sc O2 in low flow stage（S2,S5）was slightly lower than that in baseline（how much lower）flow stage（S1）and high flow stage（S4）.The MAP of S2 and S5 was slightly lower than that of S1 and S4,and the difference was not statistically significant（P>0.05）.Microcirculation was improved compared with VA-ECMO on the second day,and there was no statistical difference in the relevant parameters among the four different blood flow stages.The results of cardiac ultrasound showed that VTIAV at S2 and S5 was significantly higher than that at S1 and S4（P<0.001）CONCLUSION:In the early and middle stages supported by VA-ECMO,NIRS-Sc O2 real-time monitoring is safe and feasible with up and down regulation based on 20%of initial flow without causing cerebral and systemic hypoxia or hyperoxemia.At the same time,the downregulated VA-ECMO blood flow can meet the systemic oxygen supply without causing the deterioration of microcirculation and the increase of lactic acid,etc.,and the lower VA-ECMO blood flow significantly reduces the cardiac afterload. |
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