[Are there olfactory evoked alterations of breathing patterns?].
BACKGROUND
It is controversially discussed whether strictly olfactory stimuli are able to evoke changes of breathing patterns. A number work groups argue that the more or less noticeable irritative component of odors are responsible for a respiratory response. Other work groups regard changes of breathing pattern as an indicator for an intact smell ability during "pure" olfactory stimulation.


METHODS
12 normosmic young volunteers were repeatedly challenged with hydrogensulfide (H (2)S) for two seconds on inspiration in concentrations just above the threshold using a flow olfactometer. Clean air stimuli were presented randomly as control blanks. The breathing patterns were registered with a differential pressure transducer occluding one nostril via a tube. The signals were digitized and recorded on a PC. Nine parameters were calculated for each breath using a custom made LabView (R) software. The breath during stimulation was compared to the average of five breathing cycles prior to stimulation. An increase or reduction of each parameter was equally regarded by means of their absolute value. The sum was termed respiration index (RI).


RESULTS
The mean RI (all trials of each test person) stimulated with H (2)S varied from 201 to 570; stimulated with clean air from 85 to 188. The difference was significant (p < 0,001). A significant group-difference for each single trial was seen as well. There was no significant increase or decrease of RI during 15 successive stimulations with H (2)S.


CONCLUSIONS
Detectable short H (2)S-stimuli are able to evoke alterations of breathing patterns which can be identified by computer. Respiration-olfactometry is suitable to objectify odor perception.
Gudziol
H
H
HNO-Klinik der Friedrich-Schiller-Universität Jena. hilmar.gudziol@med.uni-jena.de
Wächter
R
R
D000328:Adult; D003196:Computer Graphics; D045853:Exhalation / Q000502:physiology*; D005260:Female; D006801:Humans; D006862:Hydrogen Sulfide; D001239:Inhalation / Q000502:physiology*; D008297:Male; D008365:Manometry / Q000295:instrumentation*; D008838:Microcomputers; D009812:Odorants; D018035:Receptors, Odorant / Q000502:physiology; D012016:Reference Values; D012684:Sensory Thresholds / Q000502:physiology; D012815:Signal Processing, Computer-Assisted / Q000295:instrumentation*; D012903:Smell / Q000502:physiology*; D014160:Transducers, Pressure
D018035:Receptors, Odorant; D006862:Hydrogen Sulfide