American journal of respiratory and critical care medicine
-
Am. J. Respir. Crit. Care Med. · Mar 1997
Randomized Controlled Trial Comparative Study Clinical TrialComparison of three oxygen delivery systems during exercise in hypoxemic patients with chronic obstructive pulmonary disease.
Oxygen therapy improves submaximal exercise tolerance in hypoxemic patients with chronic obstructive pulmonary disease (COPD). This study compared the standard nasal cannula, reservoir nasal cannula, and a demand flow device in 15 male hypoxemic patients with COPD. On six separate occasions each subject used, in a randomized order, all three systems while completing incremental cycle ergometry and a test circuit composed of tasks that simulate activities of daily living. ⋯ There was a trend toward lower Spo2 with the demand flow device (p = 0.103) during arm work above shoulder level. Although not statistically significant, reservoir nasal cannula use resulted in consistently lower tidal volume and minute ventilation during test circuit activities. Exercise tolerance was not significantly different between the three oxygen delivery systems.
-
Am. J. Respir. Crit. Care Med. · Mar 1997
Randomized Controlled Trial Clinical TrialNitrogen dioxide exposure enhances asthmatic reaction to inhaled allergen in subjects with asthma.
We investigated whether exposure to a low level (490 micrograms/m3) of nitrogen dioxide (NO2) affects bronchial responsiveness to allergen and enhances allergen-induced increase in airway responsiveness to histamine. Eighteen subjects with asthma and allergy to pollen were exposed at rest to either purified air or NO2 for 30 min followed 4 h later by an allergen inhalation challenge. Responsiveness to histamine was measured the day after. ⋯ NO2 effect on lung function was neither associated with an increase in eosinophil numbers nor with ECP levels. NO2 did not affect lung function before allergen challenge, early asthmatic reaction, and allergen-induced increase in responsiveness to histamine. These results indicate that short exposure to an ambient level of NO2 followed several hours later by allergen inhalation enhances allergen-induced late asthmatic reaction.