Chest
Volume 103, Issue 3, March 1993, Pages 693-696
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Clinical Investigations
Does Cold Air Affect Exercise Capacity and Dyspnea in Stable Chronic Obstructive Pulmonary Disease?

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Cold air may worsen asthmatic bronchoconstriction but can lessen breathlessness in normal individuals. Patients with COPD sometimes report improvement in their dyspnea in cold weather. We examined the effect of breathing cold air on exercise tolerance and the perception of breathlessness in 19 patients with stable COPD (age [±SD], 63 ± 6 years; FEV1, 0.99 ± 0.28 L) in a randomized open study. Patients exercised on a cycle ergometer breathing either room or cold air (–13°C), breathlessness being assessed by Borg scaling. Peak exercise performance improved when breathing cold air (mean ± SE), 46 ± 6 W compared with 37 ± 7 W (p<0.05) while end-exercise breathlessness fell from 4.6 ± 0.4 compared with 4.1 ± 0.5 (p<0.05) when breathing cold air. End-exercise etCO2 was higher breathing cold air (6.1 ± 0.3 kPa compared with 5.5 ± 0.3 kPa) (p<0.005). There was no difference in breathlessness at equivalent levels of ventilation. Cold air reduces breathlessness in COPD, probably by inducing relative hypoventilation.

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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  • Cited by (0)

    Manuscript received March 13; revision accepted July 30.

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