Effect of nasal air temperature on FEV1 and specific airways conductance.

We investigated whether changes in nasal air temperature affect specific airway conductance (SGaw) and one second forced expiratory volume (FEV1) in 10 asthmatic patients with a history of cold-sensitive asthma and eight healthy subjects. An air-stream (0.6 l s-1) of -15 degrees C, +22 degrees C or +37 degrees C was blown into both nostrils during a Valsalva manoeuvre. Each provocation consisted of 10 puffs of air, each of 15 s duration, at 1 min intervals. Before and at regular intervals after the provocations, SGaw and FEV1 were determined. In asthmatics, after cold air provocation, SGaw fell 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 provocations, no significant changes occurred in SGaw or FEV1. In the healthy subjects, the nasal provocations caused no significant changes in lung function. The present study shows that cold air in the nose causes a slight obstruction and warm air possibly a slight dilatation of the lower airways in patients with a history of cold-sensitive asthma but not in healthy subjects.