Am. J. Respir. Crit. Care Med., Vol 150, No. 2, 08 1994, 486-488.
Predicting nasal continuous positive airway pressure
V Hoffstein and S Mateika
Department of Medicine, St. Michael's Hospital, University of Toronto, Ontario, Canada.
We recently proposed an equation predicting the optimal level of continuous
positive airway pressure (CPAP) that abolishes sleep apnea from three
simple and easily available parameters: body mass index (BMI), neck
circumference, and apnea/hypopnea index (AHI). The present study was
designed to validate this equation in a prospective group of patients with
sleep apnea returning to the sleep laboratory for CPAP titration study. We
studied 26 patients and found that the optimal CPAP was equal to the
predicted value in 10 of 26 patients, within +/- 1 cm H2O of the predicted
value in another 10 of 26 patients, within +/- 2 cm H2O in four of 26
patients, and outside +/- 4 cm H2O in the remaining two patients. We
conclude that (1) optimal CPAP can be predicted to within +/- 2 cm H2O from
a few simple measurements, and (2) using predicted CPAP as a starting
pressure for CPAP titration, it may be possible to optimize and/or shorten
the titration study--a fact with significant implications for reducing the
cost of "diagnosis-to- treatment" polysomnography.
