Study On The Correlation Between P_ETCO₂ And P_aCO₂ Of Children In Perioperative Period Of Cardiopulmonary Bypass

Objective:To investigate the clinical significance and correlation of end-tidal carbon dioxide partial pressure(PETCO2)and arterial blood carbon dioxide pressure(PaCO2)of children with different types of congenital heart disease(CHD,Congenital heart disease)in perioperative period of cardiopulmonary bypass.Methods:A prospective analysis of 60 children(agedl-14years,ASA class Ⅱ orⅢ)undergoing cardiopulmonary bypass surgery for congenital heart disease was performed.According to echocardiographic results,the children were divided into two groups.Group A:children with left-to-right shunt,included 15 cases of atrial septal defect and 15 cases of ventricular septal defect;Group B:children with right-to-left shunt,included 30 cases of Fallot tetrad.All 60 children received intravenous general anesthesia and rapid induction of orotracheal intubation.Mechanical ventilation was taken after intubations.All the children were ventilated with tidal volume(VT)of 10 milliliter per kilogram,respiratory rate of(RR)15 to 30 per minute,inspiratory-to-expiratory ratio(I:E)of 1:2,oxygen concentration of 40%to 60%,oxygen flow rates of lto 2 liter per minuteand the PaCO2 is maintained at 35 to 45 mmHg.All the children underwent ventilator-assisted ventilation in the surgical intensive care unit for 8 hours after surgery.The PRVC model was selected of the ventilator.The children were ventilated with tidal volume of 10 milliliter per kilogram,respiratory rate of15 to 30 per minute,oxygen concentration of 40%to 60%,and maintained positive expiratory end pressure(PEEP)at 3～5cmH2O.During the ventilation period,the children’s vital signs were closely monitored.The brachial artery blood was collected for arterial blood gas analysis to measure PaCO2 at the beginning of surgery(T1),15 min after anesthesia(T2),before CPB(T3),15 min after CPB shuntdown(T4),at the end of surgery(T5),time to transfer to ICU(T6),2h after monitored in ICU(T7),4h after monitored in ICU(T8),6h after monitored in ICU(T9),8h after monitored in ICU(T10).The PaCO2 and PETCO2 were recorded at each time point.According to the result of PETCO2 and PaCO2,study the correlation of the two indexs at each time point.Results:There was no significant difference in general datas(gender,age,weight,and Class ASA)between the two groups(P>0.05).All the patients completed the surgery successfully and had stable vital signs during the period of monitorin in SICU.There were significant differences between PETCO2 and PaCO2 in different types of CHD.Analysis of correlation between PETCO2 and PaCO2 in each group:In group A,there was a positive correlation between PETCO2 and PaCO2 at each time point(the correlation was 0.55 to 0.87,P<0.01).The correlation between PETCO2 and PaCO2 decreased gradually during T2-6,and the correlation gradually increased during T7-10.There was no significant correlation between PETCO2 and PaC02(the correlation was 0.21 to 0.38,P>0.05)before operation in group B until 15 minutes after CPB.From the end of surgery to the time after monitoring 8h in SICU,PETCO2 was positively correlated with PaCO2(the correlation was 0.54 to 0.83,P<0.05).The correlation between the two indexes increased gradually during T5-10.Conclusion:During the perioperative period of cardiopulmonary bypass,the correlation between PETCO2 and PaCO2 is good,and PEETCO2 can accurately reflect the change of PaCO2 in the children with Left-to-right shunt of congenital heart disease.There was no significant correlation between PETCO2 and PaCO2 in the children with congenital heart disease of right-to-left shunting before the end of surgery,and during this time PETCO2 could not replace PaCO2.After the heart deformity is corrected,it was significant to dynamically observe the change of PEETCO2 to guide the judgment of PaCO2.