title: Oximetry alone versus portable polygraphy for sleep apnea screening before bariatric surgery.
abstract: BACKGROUND
  Screening for obstructive sleep apnea (OSA) is recommended as part of the preoperative assessment of obese patients scheduled for bariatric surgery. The objective of this study was to compare the sensitivity of oximetry alone versus portable polygraphy in the preoperative screening for OSA.
  
  
  METHODS
  Polygraphy (type III portable monitor) and oximetry data recorded as part of the preoperative assessment before bariatric surgery from 68 consecutive patients were reviewed. We compared the sensitivity of 3% or 4% desaturation index (oximetry alone) with the apnea-hypopnea index (AHI; polygraphy) to diagnose OSA and classify the patients as normal (<10 events per hour), mild to moderate (10-30 events per hour), or severe (>30 events per hour).
  
  
  RESULTS
  Using AHI, the prevalence of OSA (AHI > 10 per hour) was 57.4%: 16.2% of the patients were classified as severe, 41.2% as mild to moderate, and 42.6% as normal. Using 3% desaturation index, 22.1% were classified as severe, 47.1% as mild to moderate, and 30.9% as normal. With 4% desaturation index, 17.6% were classified as severe, 32.4% as mild, and 50% as normal. Overall, 3% desaturation index compared to AHI yielded a 95% negative predictive value to rule out OSA (AHI > 10 per hour) and a 100% sensitivity (0.73 positive predictive value) to detect severe OSA (AHI > 30 per hour).
  
  
  CONCLUSIONS
  Using oximetry with 3% desaturation index as a screening tool for OSA could allow us to rule out significant OSA in almost a third of the patients and to detect patients with severe OSA. This cheap and widely available technique could accelerate preoperative work-up of these patients.
authors.affiliation: University of Lausanne, Lausanne, Switzerland.
authors.forename: Maude
authors.initials: M
authors.lastname: Malbois
authors.forename: Vittorio
authors.initials: V
authors.lastname: Giusti
authors.forename: Michel
authors.initials: M
authors.lastname: Suter
authors.forename: Cyril
authors.initials: C
authors.lastname: Pellaton
authors.forename: Jean-Frédéric
authors.initials: JF
authors.lastname: Vodoz
authors.forename: Raphael
authors.initials: R
authors.lastname: Heinzer
mesh_terms: D000293:Adolescent; D000328:Adult; D050110:Bariatric Surgery; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009767:Obesity, Morbid / Q000503:physiopathology* / Q000601:surgery; D010092:Oximetry / Q000592:standards; D017286:Polysomnography / Q000592:standards; D011237:Predictive Value of Tests; D057234:Preoperative Period; D015995:Prevalence; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index; D020181:Sleep Apnea, Obstructive / Q000175:diagnosis* / Q000453:epidemiology / Q000473:pathology; D055815:Young Adult