title: Comparison of desaturation and resaturation response times between transmission and reflectance pulse oximeters.
abstract: BACKGROUND
  In general, there is a response time between actual arterial hypoxemia and its detection by pulse oximeters. We compared the desaturation and resaturation response times between two types of pulse oximeters, transmission and reflectance pulse oximeters, to find out which oximeter has a more rapid response time.
  
  
  METHODS
  Thirty-three ASA 1 or 2 patients were enrolled in this study. A transmission pulse oximeter was placed on the index finger and a reflectance pulse oximeter was placed on the forehead and monitored simultaneously. After the induction of general anesthesia without pre-oxygenation, we waited until the oxygen saturation value of any of two pulse oximeters declined to 90%, and then mask ventilation was started with 100% oxygen. Oxygen saturation was recorded at an interval of 2 s during this time.
  
  
  RESULTS
  The desaturation response time of SpO(2) to 95% after apnea was 82.0 s (interquartile range: 67.0-98.5 s) vs. 94.0 s (interquartile range: 84.0-106.5 s) (P<0.001) and SpO(2) to 90% was 94.0 s (interquartile range: 75.5-109.5 s) vs. 100.0 s (interquartile range: 84.5-114.5 s) (P<0.001) in the reflectance and transmission oximeters, respectively. The resaturation response time from mask ventilation to 100% SpO(2) was 23.2+/-5.6 vs. 28.9+/-7.6 s (P<0.001) in the reflectance and transmission oximeters, respectively.
  
  
  CONCLUSIONS
  In clinical situations in which rapid changes in oxygen saturation are expected, we recommend the forehead reflectance pulse oximeter because it responds more quickly in detecting oxygen desaturation and resaturation compared with the transmission pulse oximeter.
authors.affiliation: Department of Anesthesiology and Pain Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Kangnam-Ku, Seoul, Korea.
authors.forename: S J
authors.initials: SJ
authors.lastname: Choi
authors.forename: H J
authors.initials: HJ
authors.lastname: Ahn
authors.forename: M K
authors.initials: MK
authors.lastname: Yang
authors.forename: C S
authors.initials: CS
authors.lastname: Kim
authors.forename: W S
authors.initials: WS
authors.lastname: Sim
authors.forename: J A
authors.initials: JA
authors.lastname: Kim
authors.forename: J G
authors.initials: JG
authors.lastname: Kang
authors.forename: J K
authors.initials: JK
authors.lastname: Kim
authors.forename: J Y
authors.initials: JY
authors.lastname: Kang
mesh_terms: D000328:Adult; D000732:Androstanols / Q000008:administration & dosage; D018686:Anesthetics, Intravenous / Q000008:administration & dosage; D001049:Apnea / Q000097:blood; D001940:Breast / Q000601:surgery; D004867:Equipment Design; D005260:Female; D005283:Fentanyl / Q000008:administration & dosage; D005385:Fingers / Q000098:blood supply; D005546:Forehead / Q000098:blood supply; D006801:Humans; D000860:Hypoxia / Q000097:blood; D008875:Middle Aged; D003473:Neuromuscular Nondepolarizing Agents / Q000008:administration & dosage; D010092:Oximetry / Q000295:instrumentation*; D010100:Oxygen / Q000097:blood*; D015742:Propofol / Q000008:administration & dosage; D012121:Respiration, Artificial; D000077123:Rocuronium; D013965:Thyroidectomy; D013997:Time Factors; D055815:Young Adult
chemical_list: D000732:Androstanols; D018686:Anesthetics, Intravenous; D003473:Neuromuscular Nondepolarizing Agents; D010100:Oxygen; D005283:Fentanyl; D000077123:Rocuronium; D015742:Propofol