PT  - JOURNAL ARTICLE
AU  - K Larsson
AU  - S Bevegard
AU  - B Mossberg
TI  - Posture-induced airflow limitation in asthma: relationship to plasma catecholamines and an inhaled anticholinergic agent
AID  - 10.1183/09031936.93.01050458
DP  - 1988 May 01
TA  - European Respiratory Journal
PG  - 458--463
VI  - 1
IP  - 5
4099  - http://erj.ersjournals.com/content/1/5/458.short
4100  - http://erj.ersjournals.com/content/1/5/458.full
SO  - Eur Respir J1988 May 01; 1
AB  - Postural influence on ventilatory function was investigated in thirteen asthmatic subjects on three consecutive days starting at 10.00 am. Lung function was measured in the seated position before and after four hours lying supine. Peak expiratory flow (PEF) was measured every 0.5 h in the supine position. Blood samples for determination of plasma catecholamines were collected before, during and after lying supine. After the initial lung function testing, placebo or ipratropium bromide (0.125 mg) was inhaled. On the third day the whole trial was performed seated, without any drug, as a control experiment. On the placebo day lying supine induced an initial, rapid fall of PEF followed by a progressive decrease during the four hours. The progressive decrease in PEF was apparently caused by bronchoconstriction. Ipratropium bromide prevented this posture-induced bronchoconstriction. On the day seated there was also a tendency towards a decline of PEF though less pronounced than in the supine position on the placebo day. No significant alterations in plasma levels of catecholamines were observed. We conclude that the supine posture is a stimulus to bronchoconstriction in asthma, likely to be involved in nocturnal wheezing. Postural bronchoconstriction is not explained by lowered plasma levels of adrenaline, as has been suggested for nocturnal asthma. The results raise the question of whether cholinergic mechanisms are involved.