Calibration of a reflectance pulse oximeter in fetal lambs for arterial oxygen saturations below 70%.
OBJECTIVE
To calibrate a reflectance pulse oximeter developed at the Division of Perinatal Physiology, University Hospital of Zurich, for monitoring of oxygen saturations below 70%.


METHODS
Oxygen saturation measured noninvasively with the reflectance pulse oximeter in fetal sheep was compared with oxygen saturation of arterial blood samples measured by a conventional two-wavelength oximeter. Oxygen saturation was varied by stepwise reduction of the inspired oxygen concentration of the ewe.


RESULTS
A total of 58 data pairs was obtained from five fetuses, with a range of 10.9-73.5% for the reference method and 6.8-69.2% for the pulse oximetry oxygen saturation values. There was good correlation between the results obtained by the two methods (r2 = .89, P < .0001), with a 95% confidence interval of +/- 12.5%. The pulse oximeter showed a precision of 6.2% oxygen saturation.


CONCLUSIONS
The Zurich reflectance pulse oximeter offers valid measurements of oxygen saturation levels down to 10% oxygen saturation, and is therefore suitable for monitoring the fetus during delivery.
Department of Physiology, University of Odense, Denmark.
A M
AM
Carter
R
R
Stiller
V
V
König
J S
JS
Jørgensen
P
P
Svendsen
R
R
Huch
D000818:Animals; D001158:Arteries / Q000196:embryology*; D002138:Calibration; D005260:Female; D005312:Fetal Blood / Q000378:metabolism*; D010092:Oximetry / Q000295:instrumentation*; D010100:Oxygen / Q000097:blood*; D011247:Pregnancy; D012044:Regression Analysis; D012680:Sensitivity and Specificity; D012756:Sheep
D010100:Oxygen