Validation of reflectance pulse oximetry: an evaluation of a new sensor in piglets

A new reflectance pulse oximetry sensor, developed for intrapartum estimation of arterial oxygen saturation (SaO2), was calibrated and evaluated. The sensor contains two light emitting diodes of 735 and 890 nm, and a photodetector at a distance of 14 mm from both light emitting diodes.

In seven Yorkshire/Hampshire piglets, the reflectance sensor (Nellcor Puritan Bennett Inc.) was calibrated using blood sample SaO2 values. The resulting calibration line was evaluated in four Dutch piglets, by comparing pulse oximetry saturation readings (SpO2) with blood sample and intravascular fiberoptic oximetry SaO2 values. Several reflectance sensors were fixed on each animal. Desaturation levels were obtained by changing the gas mixture of oxygen/ nitrous oxide via a tracheal catheter.

In the Yorkshire/ Hampshire piglets, the standard deviation of difference (SpO2-SaO2) was 4.7% (n = 364), over an SaO2 range of 17% to 100%. In the Dutch piglets, the mean difference (SpO2-SaO2) was -1.6% and the standard deviation of difference was 5.4%, over the same SaO2 range (n = 254). Comparisons of continuous recordings of reflectance SpO2 and fiberoptic SaO2 revealed variation in individual regression lines.

This new 735/890 nm reflectance sensor demonstrates acceptable accuracy in piglets. A further evaluation during labor should assess its feasibility for fetal surveillance.