Nocturnal Asthmatics SHow Lung Function Changes at Night

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Nocturnal Asthmatics Show Lung Function Changes at Night

WESTPORT, CT (Reuters Health) Jul 12 - Increased parenchymal inflammation at night in nocturnal asthmatics may lead to distal lung dysfunction, researchers report in the June issue of the American Journal of Respiratory and Critical Care Medicine. Dr. Kraft, of the National Jewish Medical and Research Center in Denver, and colleagues note that in nocturnal asthma the distal lung exhibits "the greatest increase in inflammation from day to night." To investigate what impact this might have, the researchers studied 10 nocturnal asthmatics, 4 nonnocturnal asthmatics and 4 healthy controls. The subjects underwent bronchoscopy and measurement of peripheral airway resistance at 4 PM and 4 AM. Also established after flow was stopped for 10 sec, was "plateau pressure" — the time constant used in the calculation of peripheral compliance. None of the groups showed significant differences in peripheral airway resistance between 4 PM and 4 AM, but plateau pressure increased significantly in the nocturnal asthmatics during this time period. In addition, compared with the other groups, peripheral compliance was decreased in the nocturnal asthmatics at both 4 PM and 4 AM. The increase in plateau pressure in the nocturnal asthmatics, say the investigators, "suggests a loss or closure of collateral channels, possibly because of smooth muscle contraction, inflammation, and/or edema." In light of this, the researchers conclude "that the distal lung units, specifically the collateral channels, may be selectively altered by this cyclic inflammatory process observed in nocturnal asthma." Am J Respir Crit Care Med 2001;163:1551-1556.