Evaluation of accuracy of pulse oximetry in newborn calves

In human medicine, pulse oximetry is widely used to measure non-invasively and accurately the percentage of oxygen saturation of arterial haemoglobin (SpO(2)). Recently, pulse oximetry has been used in calves, but its accuracy has not been evaluated in newborn calves. The purpose of this study was to evaluate the accuracy of a pulse oximeter in newborn calves by comparing SpO(2) with arterial oxyhaemoglobin saturation (SaO(2)) obtained by use of a blood gas analyser. Fifty-five newborn calves were investigated from birth to 20 days old. Pulse oximetry readings and arterial blood samples were performed 5, 15, 30, 45, 60 min, 2, 3, 6, 12, 24 h and 1 and 3 weeks after birth. The transmission-type sensors of the pulse oximeter were fixed at the recommended site in the bovine species (at the base of the calf tail, where the skin had been shaved and was not pigmented) and arterial blood samples were withdrawn from the subclavian artery and analysed for SaO(2). Five-hundred paired data of SaO(2) and mean SpO(2)(mSpO(2)) were collected. Linear regression of the pooled data indicated a highly significant correlation of mSpO(2) with SaO(2) (r = 0.87;P< 0.001; mSpO(2) = 15.8 + 0.84 SaO(2)). The overall data bias value was positive (+2.1%), which indicated that the pulse oximeter tended to overestimate the SaO(2). The bias value for each SaO(2) category tended to become higher for lower ranges of SaO(2). Precision was also lower when SaO(2) values were low. The lower the SaO(2) value, the higher the positive bias (overestimation) and the lower the precision. These results suggest that pulse oximetry provides a relatively accurate non-invasive, immediate and portable method to monitor SaO(2) and to evaluate objectively the pulmonary function effectiveness in newborn calves during their adaptation to extra-uterine life.