Effect of nasal air temperature on FEV1 and specific airways conductance

We investigated whether changes in nasal air temperature affect specific ai rway conductance (SGaw) and one second forced expiratory volume (FEV1) in 1 0 asthmatic patients with a history of cold-sensitive asthma and eight heal thy subjects. An air-stream (0.6 l s(-1)) of -15 degrees C, +22 degrees C o r +37 degrees C was blown into both nostrils during a Valsalva manoeuvre. E ach provocation consisted of 10 puffs of air, each of 15 s duration, at 1 m in intervals. Before and at regular intervals after the provocations, SGaw and FEV1 were determined. In asthmatics, after cold air provocation, SGaw f ell 23% (P < 0.01) and FEV1 8% (P < 0.01). After the warm air provocations, SGaw rose 15% (P < 0.01) and FEV1 6% (P < 0.01). After the ambient air pro vocations, no significant changes occurred in SGaw or FEV1. In the healthy subjects, the nasal provocations caused no significant changes in lung func tion. The present study shows that cold air in the nose causes a slight obs truction and warm air possibly a slight dilatation of the lower airways in patients with a history of cold-sensitive asthma but not in healthy subject s.