Nasal continuous positive airway pressure (nCPAP) is an effective first-line therapy for sleep disordered breathing (SDB), but 25-50% of patients are unable to tolerate long term therapy. There have been few systematic investigations into potential causes of nCPAP intolerance. Recent studies have suggested that surgical improvement of nasal airway function also improves nasal CPAP tolerance. In this study we examined the correlation of long term CPAP tolerance with nasal airway measurements and other clinical variables, in patients with SDB.
We prospectively enrolled 44 patients presenting to an academic sleep disorders center for polysomnography. In addition to undergoing standard diagnostic polysomnography, demographic information, body mass index (BMI), Epworth Sleepiness Scale, and acoustic rhinometry measurements of nasal cross-sectional area were recorded for each patient. Of the 34 patients ultimately titrated to nCPAP, follow-up telephone interviews were conducted to determine their tolerance of therapy after 18 months.
Long term nasal CPAP tolerance data was available in 25 patients. When comparing CPAP tolerant and intolerant patients, there were no differences in age, gender, Epworth Sleepiness Scale, subjective nasal congestion, or neck circumference. Sleep study data revealed no differences in respiratory disturbance index, oxygen desaturation, sleep efficiency, or nasal CPAP pressure level. Only one factor correlated with CPAP tolerance: nasal cross-sectional area at the inferior turbinate (p=.03).
Nasal airway patency appears to be a major factor in nasal CPAP tolerance. The severity of SDB and the level of positive pressure do not affect CPAP tolerance. Other aspects of the history and physical exam, and sleep study results, were all unrelated to nCPAP tolerance.
Objective nasal airway measurements may prove important in the evaluation of the SDB patient. Such information may help clinicians predict which patients are likely to tolerate nasal CPAP therapy, and who may benefit from medical or surgical management of their nasal airway.
ParameterCPAPTolerantCPAPIntolerantp ValueAge5154NS% male6975NSBMI33.628.9NSESS12.09.0NSRDI30.235.2NSCPAP level8.387.36NSO2 saturation nadir80.779.8NSCSA (baseline)0.670.51.03CSA (decongested)0.850.66.05
CSA: nasal cross-sectional area at the inferior turbinate
Luc Morris, Other Acoustic rhinometer provided by RhinoMetrics Corporation to Kelvin C. Lee, MD.