W. Fitch

Systemic hypoxia and hyperoxia, and liver blood flow and oxygen consumption in the greyhound.

The effects of systemic hypoxia upon liver blood flow and oxygen consumption were studied in a group of six pentobarbitone anaesthetised greyhounds. The effect of systemic hyperoxia upon the same factors were also studied in a further group of six greyhounds.Hypoxia studied atPaO2 tensions of 9.3, 7.3, 5.3 and 3.3 kPa was found to increase mean arterial pressure significantly at eachPaO2 tension studied immediately the hypoxic gas mixture was introduced but this pressure had returned to control by the time 20 min had passed. At the same time a significant decrease in hepatic arterial blood flow was seen, returning to control by 20 min. No significant changes were seen in portal venous blood flow. Hepatic arterial and mesenteric vascular resistance increased significantly immediately hypoxia was instituted at allPaO2 tensions.Hepatic oxygen consumption, measured after 20 min, decreased at allPaO2 tensions, significantly at 3.3 kPa (25 mm Hg). Hepatic venous oxygen content decreased significantly at eachPaO2, decreasing to 20% of control at 3.3 kPa (25 mm Hg).Hyperoxia studied atPaO2 tensions of 26.6, 39.9 and 53.2 kPa produced no significant effects upon liver blood flow. However, there was a small increase in hepatic oxygen consumption.

Effects of nitrous oxide on liver haemodynamics and oxygen consumption in the greyhound

The effects of increasing concentrations of nitrous oxide 30, 50 and 70% on the hepatic circulation and hepatic oxygen consumption were investigated in seven normocapnic greyhounds. Hepatic arterial and portal venous blood flows were measured continuously using electromagnetic flow probes, and mean arterial pressure and cardiac output monitored. The administration of nitrous oxide caused linear decreases in hepatic arterial, portal venous and total liver blood flows. Increases in mean arterial pressure, hepatic arterial resistance and mesenteric vascular resistance were noted. There were no significant changes in hepatic oxygen consumption. It is suggested that the decrease in liver blood flow may result from alpha‐adrenoceptor stimulation.

Effects of ketamine on liver blood flow and hepatic oxygen consumption. Studies in the anaesthetised greyhound

The effects of three increasing doses of ketamine on the blood flow to, and oxygen consumption of, the liver, were studied in seven anaesthetised greyhounds. Hepatic arterial and portal venous blood flows were measured continuously using electromagnetic flow probes, and mean arterial pressure and cardiac output monitored as appropriate. Ketamine, even at the highest dose, had little effect on the blood flow to the liver: hepatic arterial blood flow and portal venous blood flow did not differ significantly from their baseline values. However, the oxygen delivery to the liver decreased due, probably, to an increase in oxygen consumption by the pre‐portal organs.

The effect of pre-operative oral fluids on morbidity following anaesthesia for minor surgery.

Postoperative morbidity and serum osmolality were studied in 46 patients who were encouraged to drink water until 3h pre‐operatively and 49 receiving the normal fasting regimen prior to minor surgery. There was significantly less thirst in the postoperative period in those patients allowed to drink and subjectively better recovery than after previous anaesthesia. There was no morbidity from ingestion of up to 11 of water 2.5h pre‐operatively. Although there was only a moderate improvement in postoperative recovery we feel that allowing patients to drink water pre‐operatively improves patient comfort, especially since patients may have to fast for much longer than guidelines recommend, simply because of the traditional organisation of operating lists.

A comparison of azapropazone and aspirin for pain relief following dental extractions

Eighty patients received one of three treatments after elective dental surgery involving multiple extractions. Group A received aspirin 600 mg, group B azapropazone 300 mg and group C azapropazone 600 mg. All drugs were administered in a double‐blind fashion. Quality of analgesia was unsatisfactory for all treatments; over 30% of patients required supplementary analgesia with an opioid. In addition there were a large number of withdrawals from the study. There were no significant differences in analgesic efficacy between groups.