title: The precision and accuracy of Nellcor and Masimo oximeters at low oxygen saturations (70%) in newborn lambs.
abstract: BACKGROUND
  Administration of oxygen in the delivery room is informed by oxygen saturation (SpO₂). An oxygen saturation range of 60%-70% is the threshold for administering oxygen in the first minutes after birth. The accuracy of newer generation oximeters to measure SpO₂ has not been compared against the 'gold standard', direct arterial blood oxygen saturation (SaO₂) when SaO₂ is low. The aim of this study was to determine the accuracy and precision of Nellcor and Masimo oximeters to measure SpO₂ when SaO₂ <70%.
  
  
  METHODS
  Prospective observational study in ventilated anaesthetised newborn lambs with an indwelling carotid artery catheter. Ventilation was adjusted to achieve hypoxaemia. Nellcor (Oxi-Max 600 with Max-N sensor) and Masimo (Rad 4 with low noise optical probe (LNOP) sensor) sensors were applied to the right forelimb (preductal). An arterial blood sample was collected at 1-5 min intervals when the animal was hypoxic. The displayed SpO₂ was recorded. We used Bland-Altman analysis to determine precision and accuracy of each oximeter when SaO₂ <70%.
  
  
  RESULTS
  17 lambs were studied, 165 measurements were obtained, 123 were SaO₂ <70%. The mean difference (±1.96 SD) Nellcor SpO₂-SaO₂ when SaO₂ <70% was 17% (-12% to 46%). The mean difference (±1.96 SD) Masimo SpO₂-SaO₂ when SaO2 <70% was 13% (-19% to 45%).
  
  
  CONCLUSIONS
  At SaO₂<70%, both monitors overestimated oxygen saturation (SpO₂) compared with the gold standard. Both oximeters were equally inaccurate when SaO₂ was low.
authors.forename: J A
authors.initials: JA
authors.lastname: Dawson
authors.forename: P
authors.initials: P
authors.lastname: Bastrenta
authors.forename: F
authors.initials: F
authors.lastname: Cavigioli
authors.forename: M
authors.initials: M
authors.lastname: Thio
authors.forename: T
authors.initials: T
authors.lastname: Ong
authors.forename: M L
authors.initials: ML
authors.lastname: Siew
authors.forename: S B
authors.initials: SB
authors.lastname: Hooper
authors.forename: P G
authors.initials: PG
authors.lastname: Davis
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D004195:Disease Models, Animal; D000860:Hypoxia / Q000097:blood / Q000175:diagnosis* / Q000628:therapy; D010092:Oximetry / Q000295:instrumentation* / Q000379:methods / Q000592:standards; D010100:Oxygen / Q000097:blood*; D010102:Oxygen Inhalation Therapy; D015203:Reproducibility of Results; D034561:Sheep, Domestic
chemical_list: D010100:Oxygen