title: Adaptive servoventilation (ASV) in patients with sleep disordered breathing associated with chronic opioid medications for non-malignant pain.
abstract: BACKGROUND
  Adaptive servoventilation (ASV) can be effective therapy for specific types of central apnea such as Cheyne-Stokes respiration (CSR). Patients treated chronically with opioids develop central apneas and ataxic breathing patterns (Biot's respiration), but therapy with CPAP is usually unsuccessful. There are no published studies of ASV in patients with sleep apnea complicated by chronic opioid therapy.
  
  
  METHODS
  Retrospective analysis of 22 consecutive patients referred for evaluation and treatment of sleep apnea who had been using opioid medications for at least 6 months, had an apnea-hypopnea index (AHI) > or = 20/h, and had been tested with ASV. Baseline polysomnography was compared with CPAP and ASV.
  
  
  METHODS
  AHI, central apnea index (CAI), obstructive apnea index (OAI), hypopnea index (HI), desaturation index, mean SpO2, lowest SpO2, time SpO2 < 90%, and degree of Biot's respiration.
  
  
  RESULTS
  Mean (SD) AHI measured 66.6/h (37.3) at baseline, 70.1/h (32.6) on CPAP, and 54.2/h (33.0) on ASV. With ASV, the mean OAI was significantly decreased to 2.4/h (p < 0.0001), and the mean HI increased significantly to 35.7/h (p < 0.0001). The decrease of CAI from 26.4/h to 15.6/h was not significant (p = 0.127). Biot's breathing persisted, and oxygenation parameters were unimproved with ASV.
  
  
  CONCLUSIONS
  Due to residual respiratory events and hypoxemia, ASV was considered insufficient therapy in these patients. Persistence of obstructive events could be due to suboptimal pressure settings (end expiratory and/or maximal inspiratory). Residual central events could be related to fundamental differences in the pathophysiology of CSR compared to opioid induced breathing disturbances.
authors.affiliation: Intermountain Sleep Disorders Center, LDS Hospital, 325 8th Ave & C Street, Salt Lake City, UT 84143, USA. rjfmd@msn.com
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Farney
authors.forename: James M
authors.initials: JM
authors.lastname: Walker
authors.forename: Kathleen M
authors.initials: KM
authors.lastname: Boyle
authors.forename: Tom V
authors.initials: TV
authors.lastname: Cloward
authors.forename: Kevin C
authors.initials: KC
authors.lastname: Shilling