[Anesthesia protocol in the swine. Effects of bleeding on circulation and acid-base equilibrium]

Haemodynamic parameters and their variations after the loss of 250 and 500 ml of blood under anaesthesia were studied in nine, 11 to 12 week-old, domestic swine weighing 37.4 +/- 2.6 kg. Premedication consisted of 2 ml azaperone i.m. Anaesthesia was induced with thiopentone, followed by suxamethonium to allow the easy placement of a cuffed endotracheal tube. Anaesthesia was maintained with phenoperidine and pancuronium. The animals were mechanically ventilated with a 50/50 nitrous oxide-oxygen mixture. A catheter was inserted in each of the femoral artery, upper hepatic vein, vena cava and portal vein. Right atrial, pulmonary and wedge pressures were measured; stroke volume, systemic and pulmonary resistances were calculated (fC 90 c X min-1, Pa 82 mmHg, Pra 4.7 mmHg, Ppa 24 mmHg, Ppw 11.6 mmHg, Q 4.45 l X min-1 and Rsa 1460 dyn X s X cm-5). The swine were then bled. After a bleed of 250 ml (t1), the haemodynamic parameters were significantly modified. After another bleed of 250 ml (t2), the heart rate only was significantly higher than at t1; but the blood transfusing could not re-establish a normal haemodynamic state. Blood samples were obtained to measure pH and total CO2 in a systemic artery, and the upper hepatic veins, vena cava and portal vein: the results suggested that the liver took part in the removal of acid metabolites.