Abstract
It is often observed that various pulmonary diseases, particularly pulmonary emphysema, bronchial asthma, and chronic bronchitis cause accumulation of CO2 in body due to low alveolar gas exchange. Measurement of alveolar pCO2 is necessary to make a confirmed diagnosis of hypercapnia.
We evaluated a clinical utility of a “screening CO2 analyzer”developed by Suematsu with a rendered complexity compared with other apparatus.
(Experimental)
A patient was ordered to make a forced expiration following resting state respiration. Breathed air was collected on the moment when the patient finished the forced expiration. Gas volume was measured by a mercury manometer before and after reaction with a CO2 absorber (saturated KOH) for 1 minute.
PACO2, the alveolar partial pressure measured by this method, was compared with PaCO2, arterial CO2 content, in 80 cases including healthy volunteers and patients of various lung distresses.
(Result)
Correlation of PACO2 and PaCO2 was expressed as n=80, r=0.857, and y=0.84x+3.41. The r value of 0.83 was obtained when we started learning this procedure, but after experienced well, the value rose up to 0.89. This may indicate a need of skillfulness.
We assessed a normal value of PACO2 using values of subjects who gave PaCO2 of 35-45mmHg. Normal, 34-43mmHg; suspicious of hypercapnia, 44-48mmHg; Abnormal, 49mmHg or more.
(Conclusion)
PACO2 value is closely correlated with PaCO2, thus seems to be substitutable for PaCO2 measurement to diagnose hypercapnia, particularly when a simpleness and quickness is required on a bed side, or to screen out abnormality from a number of cases in a short time.
The most essential point in the technique is to collect air at the finish of forced expiration.
