title: The sensitivity of room-air pulse oximetry in the detection of hypercapnia.
abstract: OBJECTIVE
  To estimate the sensitivity of room-air pulse oximetry in the detection of moderate hypercapnia.
  
  
  METHODS
  In this retrospective case-control study, charts were reviewed from patients with and without moderate hypercapnia (Pa co 2 >50 mm Hg), as determined by analysis of arterial blood gas samples obtained in the ED. Test characteristics (sensitivity, specificity, and likelihood ratios [LR) for room-air pulse oximetry < or = 96% to detect hypercapnia were calculated, as were confidence intervals.
  
  
  RESULTS
  A total of 349 charts were eligible for abstraction-92 cases and 257 controls. A room-air pulse oximetry reading < or = 96% detected 88 of 92 cases of hypercapnia. Test characteristics were as follows (with 95% confidence interval): sensitivity, 0.96 (0.89-0.99); specificity, 0.39 (0.33-0.45), LR of a room-air pulse oximetry value >96%, 0.1 (0.04-0.3); and LR of a room-air pulse oximetry value < or = 96%, 1.6 (1.4-1.7).
  
  
  CONCLUSIONS
  Room-air pulse oximetry detects moderate hypercapnia with high sensitivity.
authors: Division of Emergency Medicine, University of Maryland School of Medicine, Baltimore, MD 21201, USA. mwitt001@umaryland.edu
authors: Michael D
authors: MD
authors: Witting
authors: Sam
authors: S
authors: Hsu
authors: Carlos Andres
authors: CA
authors: Granja
mesh_terms: D000328:Adult; D000368:Aged; D002245:Carbon Dioxide / Q000097:blood; D016022:Case-Control Studies; D004635:Emergency Medicine / Q000379:methods; D006801:Humans; D006935:Hypercapnia / Q000097:blood / Q000175:diagnosis*; D008875:Middle Aged; D017063:Outcome Assessment, Health Care; D010092:Oximetry / Q000379:methods*; D012016:Reference Values; D012189:Retrospective Studies; D012680:Sensitivity and Specificity
chemical_list: D002245:Carbon Dioxide