Differential effects of airway anesthesia on ozone-induced pulmonary responses in human subjects.
We examined the effect of tetracaine aerosol inhalation, a local anesthetic, on lung volume decrements, rapid shallow breathing, and subjective symptoms of breathing discomfort induced by the acute inhalation of 0.30 ppm ozone for 65 min in 22 ozone-sensitive healthy human subjects. After 50 min of ozone inhalation FEV(1) was reduced 24%, breathing frequency was increased 40%, tidal volume was decreased 31%, and total subjective symptom score was increased (71.2, compared with 3.8 for filtered air exposure). Inhalation of tetracaine aerosol resulted in marked reductions in ozone-induced subjective symptoms of throat tickle and/or irritation (92.1%), cough (78.5%), shortness of breath (72.5%), and pain on deep inspiration (69.4%). In contrast, inhalation of tetracaine aerosol (mass median aerodynamic diameter of 3.52 microm with a geometric standard deviation of 1.92) resulted in only minor and inconsistent rectification of FEV(1) decrements (5.0%) and breathing frequency (-3.8%) that was not significantly different from that produced by saline aerosol alone (FEV(1), 5.1% and breathing frequency, -2.7%). Our data are consistent with afferent endings located within the large conducting airways of the tracheobronchial tree being primarily responsible for ozone-induced subjective symptoms and provides strong evidence that ozone-induced inhibition of maximal inspiratory effort is not dependent on conscious sensations of inspiratory discomfort.
Schelegle
E S
ES
Department of Anatomy, Physiology and Cell Biology, School of Veterinary Medicine, University of California, Davis, California 95616, USA. esschelegle@ucdavis.edu
Eldridge
M W
MW
Cross
C E
CE
Walby
W F
WF
Adams
W C
WC
D000280:Administration, Inhalation; D000293:Adolescent; D000328:Adult; D000344:Afferent Pathways / Q000187:drug effects*; D000704:Analysis of Variance; D000779:Anesthetics, Local / Q000494:pharmacology*; D005260:Female; D006801:Humans; D016014:Linear Models; D008297:Male; D010126:Ozone / Q000009:adverse effects*; D012119:Respiration / Q000187:drug effects; D012130:Respiratory Hypersensitivity / Q000139:chemically induced* / Q000503:physiopathology; D015656:Respiratory Mechanics / Q000187:drug effects; D012137:Respiratory System / Q000187:drug effects / Q000294:innervation*; D016037:Single-Blind Method; D013748:Tetracaine / Q000494:pharmacology
D000779:Anesthetics, Local; D013748:Tetracaine; D010126:Ozone