Abstract
The mini Wright peak flow meter is a useful, portable instrument for field studies but being sensitive to air density will under-read at altitude. True peak expiratory flow will increase at altitude, however, because of the decreased air density, given that dynamic resistance is unchanged. The effect of simulated altitude on peak expiratory flow (PEF) was determined in six subjects with both the mini Wright meter and a volumetric spirometer (which is unaffected by air density). With increasing altitude PEF as measured by the spirometer increased linearly with decreasing pressure, so that at a barometric pressure of 380 mm Hg* (half an atmosphere, corresponding to an altitude of 5455 m) there was a 20% increase over sea level values. The mini Wright flow meter gave readings 6% below sea level values for this altitude--that is, under-reading by 26%. Measurements of PEF made at altitude with the mini Wright meter should be corrected by adding 6.6% per 100 mm Hg drop in barometric pressure.
Full text
PDF
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Forster P., Parker R. W. Peak expiratory flow rate at high altitude. Lancet. 1983 Jul 9;2(8341):100–100. doi: 10.1016/s0140-6736(83)90078-8. [DOI] [PubMed] [Google Scholar]
- Hutcheon M., Griffin P., Levison H., Zamel N. Volume of isoflow. A new test in detection of mild abnormalities of lung mechanics. Am Rev Respir Dis. 1974 Oct;110(4):458–465. doi: 10.1164/arrd.1974.110.4.458. [DOI] [PubMed] [Google Scholar]
- Massen H., Boissinot E., Moline J. Mesure du débit de pointe et altitude. Cah Anesthesiol. 1986 Jun-Jul;34(4):341–343. [PubMed] [Google Scholar]
- SCHILDER D. P., ROBERTS A., FRY D. L. EFFECT OF GAS DENSITY AND VISCOSITY ON THE MAXIMAL EXPIRATORY FLOW-VOLUME RELATIONSHIP. J Clin Invest. 1963 Nov;42:1705–1713. doi: 10.1172/JCI104856. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Singh I., Khanna P. K., Srivastava M. C., Lal M., Roy S. B., Subramanyam C. S. Acute mountain sickness. N Engl J Med. 1969 Jan 23;280(4):175–184. doi: 10.1056/NEJM196901232800402. [DOI] [PubMed] [Google Scholar]
- Stockley R. A., Green I. D. Birmingham Medical Research Expeditionary Society 1977 Expedition: cardiopulmonary function before, during and after a twenty-one-day Himalayan trek. Postgrad Med J. 1979 Jul;55(645):496–501. doi: 10.1136/pgmj.55.645.496. [DOI] [PMC free article] [PubMed] [Google Scholar]
- WRIGHT B. M., McKERROW C. B. Maximum forced expiratory flow rate as a measure of ventilatory capacity: with a description of a new portable instrument for measuring it. Br Med J. 1959 Nov 21;2(5159):1041–1046. doi: 10.1136/bmj.2.5159.1041. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Wright B. M. A miniature Wright peak-flow meter. Br Med J. 1978 Dec 9;2(6152):1627–1628. doi: 10.1136/bmj.2.6152.1627. [DOI] [PMC free article] [PubMed] [Google Scholar]