Effects of Neurolept Anaesthesia (NLA) on Haemodynamics and Oxygen Consumption in the Dog with Special Reference to the Liver and Preportal Tissues

Abstract

The effects of neurolept anaesthesia (NLA) on central circulation, total oxygen uptake and splanchnic circulation and oxygen uptake were studied in 12 artificially ventilated dogs, basally anaesthetized with thiopental and nitrous oxide. Hepatic arterial, superior mesenteric arterial and portal venous blood flows were measured with electromagnetic flowmetry. Cardiac output was measured by thermodilution. Determinations of oxygen contents were made in arterial, pulmonary arterial, portal venous and hepatic venous blood. NLA was induced with droperidol 0.5 mg . kg-1 b.w. and fentanyl 0.01 mg . kg-1 b.w. Arterial blood pressure decreased to 63% of control value due to reductions of cardiac output to 78% and of total peripheral vascular resistance to 81% of control values. Hepatic arterial, superior mesenteric arterial and portal venous blood flows all diminished to 75% of control values. Hepatic arterial, superior mesenteric arterial and preportal tissue vascular resistances all decreased. Total oxygen uptake declined to the same extent as cardiac output, leaving the arterio-venous oxygen difference unchanged. Oxygen uptake of the preportal tissues was unaffected and hepatic oxygen uptake was not significantly reduced, although there were decreases of hepatic oxygen uptake in some of the individual dogs. It is suggested that the cardiovascular depression following NLA was due to adaptation to a lowered total oxygen uptake. It is further concluded that splanchnic circulation was well preserved due to decreases in splanchnic vascular resistances, and that splanchnic oxygen consumption was maintained by means of increased oxygen extraction.

Effects of Ephedrine on Haemodynamics and Oxygen Consumption in the Dog During High Epidural Block with Special Reference to the Splanchnic Region

“…Preportal oxygen consumption (VO~PPT) remained unchanged following both epidural block and ephedrine, and the changes in oxygen flow to the preportal tissues were countered by changes in oxygen extraction, as has been demonstrated earlier (31,32,33).…”

Effects of Enflurane on Haemodynamics and Oxygen Consumption in the Dog with Special Reference‐ to the Liver and Preportal Tissues

“…Preportal tissue oxygen consumption was unchanged following enflurane anaesthesia, as was also the case after halothane and neurolept anaesthesia (ANDREEN et al 1975, 1977, IRESTEDT & ANDREEN 1979. These tissues thus seem capable of retaining their Vo, in spite of a reduced oxygen availability.…”

Haemodynamic Effects of Labetalol-Induced Hypotension in the Anaesthetized Dog

“…Anaesthesia with fentanyl, droperidol and nitrous oxide is considered to maintain a stable cardiovascular function (Dobkin et al, 1970;Stoelting et al, 1975). The injection of droperidol and fentanyl to dogs anaesthetized with thiopentone, however, reduced CO because of a reduced heart rate (Irestedt and Andreen, 1979). In our study, fentanyl was administered as a continuous infusion to maintain a steady state during the measurements.…”