The American review of respiratory disease
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Am. Rev. Respir. Dis. · Apr 1987
Randomized Controlled Trial Comparative Study Clinical TrialRespiratory stimulants and sleep periodic breathing at high altitude. Almitrine versus acetazolamide.
We studied the effects of almitrine, acetazolamide, and placebo on the hypoxic ventilatory response (HVR), sleep periodic breathing, and arterial oxygen saturation (SaO2) in 4 healthy climbers. In a laboratory on Denali (Mt. McKinley) at 4,400 m (PB = 440 mm Hg), we used a double-blind, randomized, three-way crossover design. ⋯ The HVR (delta VE/delta SaO2%) was doubled with almitrine (p less than 0.05), but unchanged with acetazolamide. The HVR was positively related to periodic breathing (p less than 0.05). We conclude that periodic breathing during sleep at high altitude is related to the hypoxic ventilatory response, and that acetazolamide is a superior agent to almitrine for ameliorating periodic breathing.
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Am. Rev. Respir. Dis. · Apr 1987
Comparative StudyChronic exposure to sulfur dioxide. Physiologic and histologic evaluation of dogs exposed to 50 or 15 ppm.
Seven adult mongrel dogs were exposed to SO2 gas at 2 different concentrations (15 and 50 ppm) on a daily basis for 5 to 11 months. Mucous hypersecretion and airway obstruction (a sustained increase in pulmonary resistance) developed in 4 dogs exposed to 50 ppm SO2. Histologic examination of the dogs' airways demonstrated epithelial thickening and an increase in size of the mucous glands. ⋯ In the present study, with a lower exposure level to SO2 (50 versus 200 ppm), we found similar histologic findings associated with airway obstruction, but in the absence of airway inflammation, responsiveness to inhaled bronchoconstrictors was unchanged. This supports the theory that chronic airway inflammation may be associated with decreased responsiveness to inhaled bronchoconstrictors. This contrasts with the hyperresponsiveness induced by acute exposure to irritant gases noted by others.