To investigate the ease of use of four-phase high-resolution rhinomanometry (HRR), a new way of measuring nasal resistance, in measuring change in nasal resistance from supine to inclined position in a clinical sleep laboratory setting, and to correlate findings with continuous positive airway pressure (CPAP) tolerance.
Retrospective review of clinical charts.
Forty successively seen Caucasian subjects diagnosed with sleep-disordered breathing (SDB) with complete charts were analyzed. Using four-phase HRR and acoustic rhinometry, nasal resistance and minimal cross-sectional area of the nasal cavity were objectively measured with the patient in the supine position and repeated in the inclined position (30° from the horizontal plane), respectively.
From the supine to inclined position, reduction in total nasal resistance was observed in 87.5% (35 out of 40). There was a mean reduction of nasal resistance by 37.1 ± 21.6%. Five (12.5%) out of 40 subjects showed no change or mild increase in nasal resistance. Subjects with nasal resistance unresponsive to the inclined position change tended to have difficulty using nasal CPAP based on downloaded compliance card data.
Four-phase HRR and acoustic rhinometry are tests that can be easily performed by sleep specialists to characterize nasal resistance in SDB patients and determine changes in resistance with positional changes. In this study, we found that patients who did not demonstrate a decrease in nasal resistance with inclined position were more likely to be noncompliant with nasal CPAP. These measurements may help us objectively identify patients who might have trouble tolerating nasal CPAP. Laryngoscope, 2012