Effect of dehydration on phonation threshold flow in excised canine larynges.
OBJECTIVE
The minimum airflow necessary to initiate stable vocal fold vibration--phonation threshold flow (PTF)--may increase as exposure to dry air increases. A critical period of dehydration may exist after which phonation can no longer be initiated.


METHODS
We collected PTF data for 11 excised canine larynges mounted on a bench apparatus. Trials consisted of cycles of 10 seconds of phonation followed by 3 seconds of rest. During the experimental trials, subglottal flow of comparatively dry air was increased until phonation was initiated, and phonation was sustained for the remainder of the 10-second period. The subglottal flow was then decreased until phonation ceased. No saline solution was applied during the dehydration trials. During the control trials, subglottal airflow was humidified and saline solution was applied frequently to the vocal folds.


RESULTS
The PTF increased as exposure to dry air increased during the experimental trials (p = 0.010); this relationship was not statistically significant in control trials. A point existed after which phonation could not be initiated.


CONCLUSIONS
Knowledge of the effect of exposure to dry air on PTF could be useful in the clinical assessment and prevention of dehydration. Further exploration of this relationship in vivo could be used to evaluate the effectiveness of current hydration therapies and provide theoretical support for the development of new ones.
Witt
Rachel E
RE
Department of Surgery, Division of Otolaryngology-Head and Neck Surgery, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, USA.
Regner
Michael F
MF
Tao
Chao
C
Rieves
Adam L
AL
Zhuang
Peiyun
P
Jiang
Jack J
JJ