Hyperventilation as an Inductive Factor of Asthmatic Attack

Abstract

Hyperventilation (HV) induced by psychological factors or by other causes is considered to be one of the mechanisms underlying asthmatic attacks. The purpose of this investigation was to elucidate the role of HV in the production of asthmatic attacks. Ten asthmatics and seven normal subjects were asked to hyperventilate voluntarily for three minutes. Before and after voluntary HV, arterial blood-gas tension, the blood histamine level, the eosinophil count, the basophil count, the plasma cyclic AMP (cAMP) level, and the plasma cyclic GMP (cGMP) level were measured. Microvibration (MV) was recorded to observe the changes in the state of the autonomic nerve. The results were as follows : 1) Asthmatic attacks occurred after voluntary HV in asthmatics and symptoms of hyperventilation syndrome were observed in normal subjects. 2) Arterial blood-gas tension indicated respiratory alkalosis and hypoxemia after voluntary HV in both groups. 3) Plasma histamine levels tended to increase in asthmatics immediately after voluntary HV but showed no significant changes in normal subjects. Whole blood histamine levels revealed no significant alterations in either group. 4) There were no statistically significant changes of eosinophil count in asthmatics, but a significant decrease was shown immediately after voluntary HV in normal subjects. The basophil count did not show any changes in either group. 5) Both plasma cAMP levels and cGMP levels showed no significant changes in either group. 6) MV showed that there was a tendency for a sympathicotonic state to develop immediately after voluntary HV. Recovery was gradual in both groups. In asthmatics there was a tendency for recovery to be slower. In conclusion, it seemed that HV may l) work as a stressor, 2) be responsible for the release of a chemical mediator, and 3) change the state of the autonomic nerve. Therefore, it is suggested that HV induced by emotional stress etc. can produce an asthmatic attack.