Monitoring the bovine fetus during stage II of parturition using pulse oximetry

Measurement of oxygen saturation using pulse oximetry is an established method of continuous monitoring of the well-being of the human fetus during parturition. In veterinary medicine, pulse oximetry has been used almost exclusively in intensive care and anesthesiology. The goal of the present study was to investigate the physiological changes in oxygen saturation of the bovine fetus during stage II of parturition and to determine whether the findings can be used to predict postnatal acidosis. The correlation between the oxygen saturation (SpO2) measured via pulse oximetry and the oxygen saturation (SaO2) of arterial blood measured via blood gas analysis was determined in 23 newborn calves. In addition, the oxygen saturation was monitored continuously via pulse oximetry (FSpO2) in 33 bovine fetuses during stage II of parturition. Correlations between the FSpO2 values during the last 30 and 5 min of stage II of parturition and the postpartum values for pH, partial pressures of oxygen and carbon dioxide, bicarbonate concentration, BE, SaO2 and lactate concentration in arterial blood were determined. There was a high correlation between SpO2 and SaO2 postpartum (r = 0.923). The FSpO2 values correlated moderately with the pH and BE and weakly with the lactate concentration postpartum; calves with a pH < 7.2, a BE < −3 mM/L or a lactate concentration of >5.4 mM/L had significantly lower FSpO2 values than non-acidotic calves. FSpO2 values <30% for a period of at least 2 min had the highest predictive value for a calf born with a pH < 7.2. Pulse oximetry is a novel method of monitoring the bovine fetus during parturition; however, technical modifications are required to improve its usefulness.