title: Nasal versus oronasal continuous positive airway pressure masks for obstructive sleep apnea: a pilot investigation of pressure requirement, residual disease, and leak.
abstract: OBJECTIVE
  This single-blinded, randomized, controlled pilot study aimed to investigate whether there is a difference between nasal and oronasal masks in therapeutic continuous positive airway pressure (CPAP) requirement, residual disease, or leak when treating obstructive sleep apnea (OSA) and if differences were related to measures of upper airway size.
  
  
  METHODS
  Patients with severe OSA currently using CPAP at ≥4 h/night with a nasal mask were examined (including Mallampati scale, incisal relationship, and mandibular protrusion) and then randomized to receive auto-positive airway pressure (PAP) or fixed CPAP at a manually titrated pressure for 1 week each at home, with immediate crossover. Within each week, a nasal mask and two oronasal masks were to be used for two or three nights each in random order. Data were downloaded from the device.
  
  
  RESULTS
  Twelve patients completed the trial (mean ± SD AHI 59.8 ± 28.6 events/h; CPAP 11.1 ± 3.2 cmH(2)O; BMI 37.7 ± 5.0 kg/m(2)). During auto-PAP, the median 95th percentile pressure delivered with all masks was within 0.5 cmH(2)O (p > 0.05). During CPAP, median residual AHI was 0.61 (IQR = 1.18) for the nasal mask, 1.70 (IQR = 4.04) for oronasal mask 1, and 2.48 (IQR = 3.74) for oronasal mask 2 (p = 0.03). The 95th percentile leak was lowest with the nasal mask during both CPAP and auto-PAP (both p < 0.01). Differences in pressure or residual disease were not related to measures of upper airway shape or body habitus.
  
  
  CONCLUSIONS
  In obese OSA patients changing from a nasal to oronasal mask increased leak and residual AHI but did not affect the therapeutic pressure requirement. The findings of the current study highlight mask leak as the major difficulty in the use of oronasal masks.
authors.affiliation: WellSleep Sleep Investigation Centre, Department of Medicine, University of Otago, Wellington, New Zealand. jessie.bakker@otago.ac.nz
authors.forename: Jessie P
authors.initials: JP
authors.lastname: Bakker
authors.forename: Alister M
authors.initials: AM
authors.lastname: Neill
authors.forename: Angela J
authors.initials: AJ
authors.lastname: Campbell
mesh_terms: D000399:Air Pressure; D015992:Body Mass Index; D001944:Breath Tests; D002648:Child; D002675:Child, Preschool; D045422:Continuous Positive Airway Pressure / Q000295:instrumentation*; D004867:Equipment Design; D004868:Equipment Failure; D005260:Female; D006801:Humans; D006861:Hydrogen Peroxide / Q000032:analysis; D008297:Male; D008397:Masks; D009566:Nitrates / Q000032:analysis; D009573:Nitrites / Q000032:analysis; D010865:Pilot Projects; D017286:Polysomnography; D020181:Sleep Apnea, Obstructive / Q000175:diagnosis / Q000628:therapy*
chemical_list: D009566:Nitrates; D009573:Nitrites; D006861:Hydrogen Peroxide