SAMPLING METHOD FOR MEAN ALVEOLAR GAS IN NORMAL SUBJECTS AND PATIENTS WITH RESPIRATORY-DISEASE

  • 1 January 1976
    • journal article
    • research article
    • Vol. 12  (5) , 625-636
Abstract
An alveolar gas sampling method based on the criterion of equality of mean alveolar (.hivin.RA) and expired (.hivin.RE) respiratory quotients was described. Expired gas is sampled at an expired volume equal to VT[tidal volume]/2 + VD [volume of dead spare gas] using a mechanical sampler controlled by an analog computer. Eleven normal subjects and 50 patients with cardiopulmonary disease were tested. When the difference between mean alveolar and expired respiratory quotients did not exceed 0.05, the result was considered to be satisfactory. Such results were obtained in 40 patients and all of the normal subjects. For the remaining 10 patients, either experimental error and/or particular non-homogeneities in ventilation seemed to be the cause of the unsatisfactory results. Arterial to alveolar PCO2 [O2 tension] differences were calculated. The mean difference in normal subjects was never negative (1.86 .+-. 1.58 torr).

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