RESUMO
Objective To estimate the arterial-to-end-tidal carbon dioxide tension difference (Pa-ET CO 2 )in children with cyanotic or acyanotic congenital heart diseases;evaluate whether hyper-ventilation can reduce the tension difference or not;analyze the effect of sevofleurane on Pa-ET CO 2 . Methods One hundred and twenty patients (male 60 cases,female 60 cases,aged 1 month-6 years, ASA class Ⅱ or Ⅲ)undergoing selective cardiac surgery were randomly divided into 6 groups (n =20 each)based on right-to-left or left-to-right intracardic shunts:group A1,cyanotic with sevoflurane of 0.5 MAC;group A2,cyanotic with sevoflurane of 1.0 MAC;group B1,acyanotic with sevoflurane of 0.5 MAC;group B2,acyanotic with sevoflurane of 1.0 MAC;group C1,cyanotic with no inter-vention factors;group C2,acyanotic with no intervention factors.All the children received general an-aesthesia after placing an intravenous and arterial catheter.The value of PET CO 2 ,SpO 2 ,PaCO 2 , SaO 2 ,Hct and temperature(nasopharyngeal temperature and rectal temperature)were obtained before operation,after hyperventilation(the control groups without hyperventilation)and five minutes before surture sternum.Results The values of Pa-ET CO 2 were more than the normal one in six groups before operation.The value of Pa-ET CO 2 in group B1 was less than that in group A1,that in group B2 was less than that in group A2 and that in group C2 was less than that in group C1 before operation (P <0.01).Compared with the time point before operation,the values of Pa-ET CO 2 in groups A1,A2,B1 and B2 decreased significantly after hyperventilation (P < 0.05 or P < 0.01 ).Moreover, this reduction was more significant in groups B1 and B2.Compared with the time point before operation, the values of Pa-ET CO 2 in groups B1,B2,C2 increased significantly (P <0.01)and that in groups A1, A2,C1 decreased significantly (P <0.05)at 5 minutes before surture sternum.There was no statisti-cal difference at three different time points between group A1 and A2,B1 and B2.Conclusion The value of Pa-ET CO 2 in cyanotic children increased more significantly than that in acyanotic children.Hy-perventilation can reduce the value of Pa-ET CO 2 especially in acynanotic children with pulmonary con-gestion.The concentration (from 0.5 MAC to 1.0 MAC)of sevoflurane had little effect on the value of Pa-ET CO 2 .