title: Characterization of breathing patterns during patient-controlled opioid analgesia.
abstract: BACKGROUND
  Respiratory rate is an important measurement in patient care, but accurate measurement is often difficult. We have developed a simple non-invasive device to measure respiratory movements in clinical circumstances, with minimal interference with the patient. We investigated respiratory patterns in patients receiving postoperative morphine analgesia to assess the capacity of the device to detect abnormalities.
  
  
  METHODS
  We studied subjects during self-administered opioid analgesia after major gynaecological surgery, and related the derived signals with a signal from a nasal cannula. Respiratory movement signals were transmitted wirelessly to a recorder from two encapsulated tri-axial accelerometer (RESpeck) sensors. We analysed the signals using two different sensor placements, each for 30 min. The nasal cannula signal was used to classify breathing patterns as obstructive or non-obstructed.
  
  
  RESULTS
  We studied 20 patients for a mean duration of 49 min each. Breathing patterns were very variable, between and within patients. The median breathing rates ranged from 6.4 to 19.5 bpm. Breathing was partly obstructed in 10 patients, and six patients had repeated cycles of obstruction and transient recovery. In these patients, we found a consistent and statistically significant pattern of changes in chest wall movement, with increased abdominal and decreased rib cage movement during obstruction. In patients with slow respiratory rates, breath-to-breath times were highly variable.
  
  
  CONCLUSIONS
  In undisturbed subjects receiving patient-controlled morphine analgesia after surgery, abnormal breathing patterns are extremely common. Cyclical airway obstruction is frequent and associated with a typical pattern of changes in chest wall movement.
authors: Department of Anaesthesia and Pain Medicine, University of Edinburgh, Royal Infirmary, 51 Little France Crescent, Edinburgh EH16 4HA, UK.
authors: G B
authors: GB
authors: Drummond
authors: A
authors: A
authors: Bates
authors: J
authors: J
authors: Mann
authors: D K
authors: DK
authors: Arvind
mesh_terms: D061725:Accelerometry / Q000379:methods; D000328:Adult; D000368:Aged; D000402:Airway Obstruction / Q000139:chemically induced / Q000175:diagnosis / Q000503:physiopathology; D016058:Analgesia, Patient-Controlled / Q000009:adverse effects* / Q000379:methods; D000701:Analgesics, Opioid / Q000008:administration & dosage / Q000009:adverse effects*; D013509:Gynecologic Surgical Procedures; D006801:Humans; D008875:Middle Aged; D008991:Monitoring, Physiologic / Q000379:methods; D009068:Movement / Q000502:physiology; D010149:Postoperative Pain / Q000517:prevention & control*; D011182:Postoperative Care / Q000379:methods; D012120:Respiration Disorders / Q000139:chemically induced / Q000175:diagnosis* / Q000503:physiopathology; D056152:Respiratory Rate / Q000187:drug effects; D012815:Signal Processing, Computer-Assisted; D035441:Thoracic Wall / Q000503:physiopathology
chemical_list: D000701:Analgesics, Opioid
keywords: monitoring, physiologic; respiration disorders; respiratory rate