Use of an acoustic helium analyzer for measuring lung volumes.
J Appl Physiol Respir Environ Exerc Physiol
; 50(1): 203-9, 1981 Jan.
Article
em En
| MEDLINE
| ID: mdl-7204187
ABSTRACT
We have evaluated the use of an acoustic gas analyzer (AGA) for the measurement of total lung capacity (TLC) by single-breath helium dilution. The AGA has a rapid response time (0-90% response = 160 ms for 10% He), is linear for helium concentration of 0.1-10%, is stable over a wide range of ambient temperatures, and is small and portable. We plotted the output of the AGA vs. expired lung volume after a vital capacity breath of 10% He. However, since the AGA is sensitive to changes in speed of sound relative to air, the AGA output signal also reports an artifact due to alveolar gases. We corrected for this artifact by replotting a single-breath expiration after a vital capacity breath of room air. Mean alveolar helium concentration (HeA) was then measured by planimetry, using this alveolar gas curve as the base line. TLC was calculated using the HeA from the corrected AGA output and compared with TLC calculated from HeA simultaneously measured using a mass spectrometer (MS). In 12 normal subjects and 9 patients with chronic obstructive pulmonary disease (COPD) TLC-AGA and TLC-MS were compared by linear regression analysis; correlation coefficient (r) was 0.973 for normals and 0.968 for COPD patients (P less than 0.001). This single-breath; estimation of TLC using the corrected signal of the AGA vs. Expired volume seems ideally suited for the measurement of subdivisions of lung volume in field studies.
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Coleções:
01-internacional
Contexto em Saúde:
1_ASSA2030
Base de dados:
MEDLINE
Assunto principal:
Capacidade Pulmonar Total
/
Hélio
/
Medidas de Volume Pulmonar
Limite:
Humans
Idioma:
En
Revista:
J Appl Physiol Respir Environ Exerc Physiol
Ano de publicação:
1981
Tipo de documento:
Article