Chest
Clinical InvestigationsHelium-Oxygen Breathing in Severe Chronic Obstructive Pulmonary Disease
Section snippets
Subjects
Fifteen stable adult male patients ranging in age from 52 to 73 years (mean 61 years) with the diagnosis of severe COPD were studied. Informed written consent was obtained from all patients. All patients had either a forced expiratory volume in one second (FEV1) less than or equal to 1 L; or the ratio of forced expiratory volume in one second to forced vital capacity (FEV1/FVC %) less than or equal to 50 percent. Nine subjects were outpatients followed up in our pulmonary clinic. Six were
Results
Our subjects had FEV1 values that ranged from 0.55 to 1.30 L (mean ± SEM: 0.87± 0.07 L); the percentage of predicted FEV1 ranged from 17 to 51 percent (mean ± SEM: 30±3 percent) and FEV1/FVC% ranged from 16 to 47 percent (mean ± SEM: 35 ± 2 percent). Ten of the 15 patients had a 20 percent or greater improvement in the FEV1 after inhalation of an isoetharine HC1 aerosol. Baseline arterial blood gas measurements obtained at an FIo2 ranging from 0.21 to 0.27 (depending on the individual needs of
Discussion
Our finding of a decreased FRC while breathing He-CO2 is consistent with the anticipated effects of breathing a less dense gas in severe COPD.
In patients who are substantially hyperinflated, it is possible that expiratory pleural pressures can be sufficiently positive during resting breathing to result in expiratory flow limitation, while at the same time the patients may be maintaining elevated resting lung volumes by continuing to use inspiratory muscles during expiration. This circumstance
Acknowledgments
Mrs. Lida-Claire Gamon and Mr. Charles M. Goldman provided skillful technical assistance.
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Supported in part by NIH grants HL-25233, HL-25830, and the Medical Research Service of the Veterans Administration.
Manuscript received August 27; revision accepted November 26.
Reprint requests: Dr. Swidwa, VA Medical Center, Brecksville, Ohio 44141