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 accurac y has not been evaluated in newborn calves. The purpose of this study was t o 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 birt h to 20 days old. Pulse oximetry readings and arterial blood samples were p erformed 5, 15, 30, 45, 60 min, 2, 3, 6, 12, 24 h and 1 and 3 weeks after b irth. 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(at the base of the calf tail, wher e the skin had been shaved and was not pigmented) and arterial blood sample s were withdrawn from the subclavian artery and analysed for SaO(2).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 corre lation of mSpO(2) with SaO(2) (r = 0.87; P < 0.001; mSpO(2) = 15.8 + 0.84 S aO(2)). The overall data bias value was positive (+2.1%), which indicated t hat the pulse oximeter tended to overestimate the SaO(2). The bias value fo r 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) v alue, the higher the positive bias (overestimation) and the lower the preci sion. These results suggest that pulse oximetry provides a relatively accur ate non-invasive, immediate and portable method to monitor SaO(2) and to ev aluate objectively the pulmonary function effectiveness in newborn calves d uring their adaptation to extra-uterine life. (C) 2000 Harcourt Publishers Ltd.