Abstract: Objective To investigate the correlation and clinical value between PetCO₂ and PaCO₂ in stable and acute chronic obstructive pulmonary diseases(COPD) patients.Methods Fifty persons were tested in our study,20 healthy persons as control(A group) and 30 COPD patients.30 COPD patients were divided into two groups,acute COPD patients(B group,fore-treatment) and stable COPD patients(C group,post-treatment).The value of PetCO₂ and PaCO₂ were measured at the same time,and then calculate the value of ADCO₂.Results 1) The value of PaCO₂ and ADCO₂ in B and C groups were significantly higher than those in A group(all P<0.01).Compared with A group,the value of PetCO₂ in B group decreased significantly(P<0.01),but no significant changes in PetCO₂ value was found in C group(P>0.05).Compared with B group,the value of PetCO₂ in C group increased significantly,and the value of PaCO₂ and ADCO₂ in C group decreased significantly(all P<0.01).2) PetCO₂ was significantly correlated with PaCO₂ in both A and C group(r=0.95 and 0.56,all P<0.01).Conclusion PetCO₂ can be used to judge the change of PaCO₂ in normal and stable patients of COPD,but it is not very sensitive and can not be used directly to judge the change of PaCO₂ in acute patients of COPD.ADCO₂ can be used to reflect the severity of acute COPD patients.

Key words: end-tidal carbon dioxide tension, partial pressure of carbon dioxide, chronic obstructive pulmonary diseases