title: Neural drive during continuous positive airway pressure (CPAP) and pressure relief CPAP.
abstract: BACKGROUND
  Pressure release continuous positive airway pressure (CPAP) is an evolution of CPAP that has been reported to improve patient comfort. We hypothesised the pressure release would lead to unloading of the inspiratory muscles and therefore conducted a prospective double-blind cross-over physiological study of autotitrating CPAP (APAP) against autotitrating pressure relief CPAP (PR-APAP).
  
  
  METHODS
  Eleven patients with severe obstructive sleep apnoea (OSA; mean AHI 74.5+/-14.4/h) were studied. We assessed neural drive by recording the oesophageal pressure, gastric pressure, transdiaphragmatic pressure and the diaphragm EMG during overnight polysomnography.
  
  
  RESULTS
  Both APAP and PR-APAP significantly reduced neural respiratory drive. Transdiaphragmatic pressure swings during apnoea (30.2+/-11.5 cm H2O) before treatment decreased to 9.1+/-5.3 cm H2O for PR-APAP and 8.5+/-3.7 cm H2O for APAP. The transdiaphragmatic pressure and the diaphragm EMG did not differ significantly between APAP and PR-APAP. The gastric pressure swing at expiration phase disappeared during both APAP and PR-APAP when sleep respiratory events were eliminated.
  
  
  CONCLUSIONS
  PR-APAP is not superior to APAP in terms of reducing neural respiratory drive. It is unnecessary to replace conventional APAP with PR-APAP for patients who have been successfully treated with traditional APAP.
authors.affiliation: Guangzhou Medical College, Guangzhou Institute of Respiratory Diseases, 151 Yanjiang Road, Guangzhou 510120, China.
authors.forename: Y M
authors.initials: YM
authors.lastname: Luo
authors.forename: Z H
authors.initials: ZH
authors.lastname: Qiu
authors.forename: H D
authors.initials: HD
authors.lastname: Wu
authors.forename: J
authors.initials: J
authors.lastname: Steier
authors.forename: C
authors.initials: C
authors.lastname: Jolley
authors.forename: N S
authors.initials: NS
authors.lastname: Zhong
authors.forename: J
authors.initials: J
authors.lastname: Moxham
authors.forename: M I
authors.initials: MI
authors.lastname: Polkey
mesh_terms: D000328:Adult; D015992:Body Mass Index; D045422:Continuous Positive Airway Pressure / Q000379:methods*; D018592:Cross-Over Studies; D003964:Diaphragm / Q000294:innervation; D004311:Double-Blind Method; D004562:Electrocardiography; D004576:Electromyography; D004947:Esophagus / Q000294:innervation; D005260:Female; D006801:Humans; D001239:Inhalation / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D009415:Nerve Net / Q000502:physiology*; D017286:Polysomnography; D011312:Pressure; D011446:Prospective Studies; D012132:Respiratory Muscles / Q000502:physiology; D012720:Severity of Illness Index; D020181:Sleep Apnea, Obstructive / Q000175:diagnosis / Q000503:physiopathology* / Q000628:therapy*; D012894:Sleep Stages; D013270:Stomach / Q000294:innervation; D016683:Supine Position