MEASUREMENT OF NASAL IRRITANT SENSITIVITY TO PULSED CARBON-DIOXIDE - A PILOT-STUDY

Nasal irritation and associated symptoms (e.g., nasal congestion, rhin orrhea, sinus headache) are important air-pollution-related health com plaints, particularly-in so-called problem buildings. Individual diffe rences in nasal irritant sensitivity are therefore of both clinical an d regulatory interest. To document such differences, one must first fu nctionally define perceptual acuity to airborne irritants. In an adapt ation of an established sensory testing method, the authors used the o dorless irritant carbon dioxide in an electronically controlled diluti on apparatus to deliver brief (approximate to 3 s) pulses at controlle d levels (10%-70%, vol/vol), synchronized with the inspiratory phase o f the respiratory cycle. Investigators who use this apparatus can use a variant of the forced-choice paradigm for threshold determination to document nasal irritant sensitivity. The authors recruited 30 adult v olunteers (17 males, 13 females; average age = 41 y, range 19-79 y) fr om a university laboratory complex and from the general community. Wit hin this group, there was a skewed distribution of carbon dioxide thre sholds (arithmetic mean = 28%, geometric mean = 27% [vol/vol]). In uni variate analyses, geometric mean carbon dioxide thresholds differed si gnificantly with respect to smoking status (36% carbon dioxide in smok ers versus 25% in nonsmokers; p < .005), but not with respect to age, gender, or self-reported history of allergic rhinitis. In a multivaria te analysis, gender also approached significance; females tended to sh ow better perceptual acuity than males (p = .06). Neither self-reporte d ''vasomotor rhinitis'' symptoms nor self-reported symptomatic reacti vity to environmental tobacco smoke predicted carbon dioxide threshold s. Pulsed carbon dioxide is well tolerated by subjects who participate in a threshold detection task; the procedure yields a potential endpo int with which to compare individuals (and groups) with respect to nas al irritant perceptual acuity. The relationship between such acuity an d nasal physiologic reactivity-as well as the generalizability of such measures to other, more environmentally realistic irritants-has yet t o be defined.