A NEW PROCEDURE FOR THE CONTINUOUS MEASUREMENT OF OXYGEN-CONSUMPTION IN PIGS

Whole-body oxygen (O2) consumption was measured continuously in pigs f rom the product of blood flow through the pulmonary artery and arterio -venous (AV) difference of blood O2 content across the lungs (pulmonar y AV procedure). Blood flow in the pulmonary artery, a measure of card iac output, was monitored continuously using a transit-time ultrasound flow probe surgically implanted around the artery. The O2 content of pulmonary artery blood, which represents mixed venous blood O2 saturat ion (SvO2) was recorded continuously by fibre-optic oximetry. The rela tive constancy of arterial blood oxygen saturation (SaO2), obtained by catheterization of the saphenous artery, obviated the need for contin uous monitoring. Complete recovery from surgical procedures, as indica ted by the absence of infection and a return to pre-surgery food intak e, occurred in 3-5 days. The combination of transit-time ultrasound an d fibre-optic oximetry allowed the pulmonary AV procedure to provide c ontinuous data on the oxygen consumption of growing pigs at high tempe ratures.