Chest
Clinical InvestigationsDoes Cold Air Affect Exercise Capacity and Dyspnea in Stable Chronic Obstructive Pulmonary Disease?
Section snippets
Patients
We studied 21 patients (8 female) with stable nonasthmatic COPD. Mean(±SD) age was 63 ± 6 years, mean baseline FEV1 was 0.99 ± 0.28 L (37.5 percent predicted), mean FRC was 5.3 ± 0.9 L, and mean Dco was 5.4 ± 2.4 mmolmin–1kPa–1. Bronchodilator reversibility was assessed prior to the study, mean FEV1 increasing by 0.17 ± 0.06 ml 15 min after 5 mg nebulized salbutamol. No patients were known to increase their FEV1 by more than 200 ml after a trial of oral corticosteroid therapy (30 mg prednisone
RESULTS
Resting data showed no significant differences between the spirometry, heart rate, oxygen saturation (SaO2), petCO2, or dyspnea scores between the study days, nor were the resting minute ventilation or breathing pattern different in those in whom it was measured.
The maximal exercise level achieved was higher breathing chilled air 46 ± 6 W compared with 38 ± 7 W breathing room air (p<0.05). Peak work load was not related to the initial FEV1 whether expressed as an absolute value or as percent
DISCUSSION
The beneficial effects of breathing cool air on the sensation of breathlessness have been recognized clinically for many years. Thus, Trousseau,12 writing in 1868, noted that “an asthmatic person like the open air … he must often have the windows open in the depths of winter as if it were summer.” Our present studies provide a physiologic rationale for these observations and suggest that relative hypoventilation occurs when breathing cold air despite the powerful physiologic stimulus of
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Manuscript received March 13; revision accepted July 30.