title: Obesity hypoventilation syndrome, sleep apnea, overlap syndrome: perioperative management to prevent complications.
abstract: OBJECTIVE
  The prevalence of sleep disordered breathing (SDB) is increasing proportional to the prevalence of obesity. Although anesthesiologists are familiar with obstructive sleep apnea (OSA) - the most common SDB, anesthesiologists may not be aware of other SDB such as obesity hypoventilation syndrome (OHS) and overlap syndrome (combination of OSA and chronic obstructive pulmonary disease). The present review provides an update of information regarding the perioperative management of OHS and overlap syndrome.
  
  
  RESULTS
  OHS and overlap syndrome are associated with significant comorbid conditions and more perioperative morbidity than OSA alone. Similar to OSA, most of the OHS patients are undiagnosed. An increase in serum bicarbonate level is a surrogate marker of hypercapnia. Because 90% of OHS patients have OSA, preoperative screening for OSA combined with estimation of serum bicarbonate level may detect the majority of the patients with OHS. In patients with OSA, OHS, and overlap syndrome, improvement in the perioperative outcome has been shown by initiating positive airway pressure therapy.
  
  
  CONCLUSIONS
  Identification and preoperative optimization of these high-risk patients are most important. A protocol-based risk mitigation is necessary for improving the intraoperative and postoperative outcome of these patients. As a perioperative physician, anesthesiologists have a key role in the management of patients with SDB.
authors: aWest Coast District Health Board, Greymouth, New Zealand bDepartment of Anesthesiology, Toronto Western Hospital, University Health Network, University of Toronto, Toronto, Canada.
authors: Raviraj
authors: R
authors: Raveendran
authors: Jean
authors: J
authors: Wong
authors: Mandeep
authors: M
authors: Singh
authors: David T
authors: DT
authors: Wong
authors: Frances
authors: F
authors: Chung
mesh_terms: D000758:Anesthesia / Q000009:adverse effects / Q000379:methods / Q000592:standards; D001639:Bicarbonates / Q000097:blood; D017558:Elective Surgical Procedures / Q000009:adverse effects*; D006801:Humans; D010845:Obesity Hypoventilation Syndrome / Q000097:blood / Q000150:complications* / Q000175:diagnosis / Q000453:epidemiology; D019990:Perioperative Care / Q000009:adverse effects / Q000379:methods* / Q000592:standards; D011183:Postoperative Complications / Q000453:epidemiology / Q000209:etiology / Q000517:prevention & control*; D017410:Practice Guidelines as Topic; D015995:Prevalence; D029424:Pulmonary Disease, Chronic Obstructive / Q000097:blood / Q000150:complications* / Q000175:diagnosis / Q000453:epidemiology; D018570:Risk Assessment
chemical_list: D001639:Bicarbonates