PubMed Health⌕ Search

Biomedical subjects

M Andreen

Publications and source records attributed to M Andreen.

31 records · Page 2Linked to original sources
PubMed1979

Effects of neurolept anaesthesia (NLA) on haemodynamics and oxygen consumption in the dog with special reference to the liver and preportal tissues.

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.

Anesthetics↗
PubMed1979

Effects of enflurane on haemodynamics and oxygen consumption in the dog with special reference to the liver and preportal tissues.

The effects of enflurane anaesthesia on central circulation, total oxygen uptake, splanchnic circulation and splanchnic oxygen uptake were studied in 10 artifically 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. The end-tidal enflurane concentration was kept at about 1 MAC (= 2.2%). Arterial blood pressure diminished 54% of control value due to decreases of cardiac output to 65% and of total peripheral vascular resistance to 81% of control values. Hepatic arterial, superior mesenteric arterial and portal venous blood flows decreased to 65-70% of control levels and the corresponding vascular resistances all declined to about 80-85% of control values. Total oxygen uptake decreased, but less than cardiac output, leading to an increased arterio-venous oxygen content difference. Oxygen uptake of the preportal tissues was unchanged and hepatic oxygen uptake was not significantly altered, although there were decreases in hepatic oxygen uptake in some of the individual experiments. It is suggested that the cardiovascular depression following enflurane anaesthesia in the dog was due, to a great extent, to a primary myocardial depression. It is further concluded that the splanchnic blood flows were relatively well preserved, due to decreases in splanchnic vascular resistances, and that hepatic and preportal tissue oxygen consumptions were maintained by increased oxygen extraction.

Anesthesia, General↗
PubMed1979

Effects of enflurane on splanchnic circulation.

A brief summary of the anatomy and physiology of the splanchnic circulation is presented. The influence of 1 MAC enflurane anaesthesia on splanchnic circulation and oxygenation was studied in 10 dogs. Superior mesenteric arterial, portal venous and hepatic arterial blood flows decreased less than mean arterial blood pressure, due to reductions in superior mesenteric arterial, preportal vascular and hepatic arterial resistances. It is suggested that these reactions within the splanchnic circulation are mainly dependent on normal autoregulative responses elicited by the fall in blood pressure. Oxygen consumption of the preportal tissues and the liver was unchanged as a result of increased extraction of oxygen.

Anesthesia, Inhalation↗
PubMed1979

Circulatory effects of somatostatin in anaesthetized dogs.

Five anaesthetized dogs were given 20 infusions of 1--9 min duration of somatostatin in a dosage of 0.2--15 micrograms.kg-1.min-1. Cardiac output was measured by thermodilution. Electromagnetic blood flow measurements were simultaneously performed in the hepatic artery proper, the left gastric artery, the superior pancreatico-duodenal artery, the superior mesenteric artery and in the portal vein. Mean arterial blood pressure was recorded continuously. Somatostatin reduced all splanchnic blood flows measured by 15--35%, except for the hepatic artery flow, which was increased by 5% or unaffected. Cardiac output and mean arterial pressure were unchanged. Somatostatin was thus demonstrated to exert a specific vasoactivity in the splanchnic area without influencing central circulation. It is suggested that somatostatin acts directly on the vascular smooth muscle.

Abdomen↗
PubMed1978

Hepatic release of fluoride from halothane under hypoxic and non-hypoxic conditions in the dog.

Six dogs were subjected to halothane anaesthesia under hypoxic and non-hypoxic conditions. Plasma fluoride levels in hepatic venous and arterial blood, as well as blood flow to the liver, were measured during anaesthesia. The amount of fluoride released by the liver could thus be calculated. Release of fluoride took place in all animals during non-hypoxic halothane anaesthesia. The amount released varied between the individual animals and in three of them it rose further during hypoxic anaesthesia. The occurrence of defluorination of halothane, even under nonhypoxic conditions, may indicate a reductive metabolism in at least some parts of the liver. The significance of this hypothesis is discussed.

Acid-Base Equilibrium↗
PubMed1977

The different responses of the hepatic arterial bed to hypovolaemia and to halothane anaesthesia.

Ten dogs were subjected to a period of hypovolaemia (bleeding volume: 2% of body weight) and to a period of halothane anaesthesia (end-tidal halothane concentration: 1%). Mean arterial blood pressure decreased to 79% of control value during hypovolaemia and to 58% of control value during halothane anaesthesia. Mean total peripheral and preportal vascular resistances increased during hypovolaemia and were unchanged during halothane. Mean hepatic arterial and portal venous blood flows decreased to 82% and 55% of control values, respectively, during hypovolaemia, and to 41% and 56% of control value, respectively, during exposure to halothane. Mean hepatic arterial resistance was unchanged during hypovolaemia, but increased during halothane. Mean hepatic oxygen consumption did not change significantly during hypovolaemia, but decreased during halothane anaesthesia, in spite of an increased extraction of oxygen from both the hepatic arterial and the portal venous blood. Possible mechanisms which may maintain oxygen supply to the liver by increasing the hepatic arterial fraction of total liver blood flow when portal venous blood flow is reduced are discussed. It is concluded that this mechanism is upset or inhibited during halothane anaesthesia.

Anesthesia, Inhalation↗
PubMed1976

Uptake of bupivacaine (Marcaine) in liver and lung after intramuscular administration in the dog.

The uptake of bupivacaine in the liver and lung of the dog was studied 10,20,30 and 60 min after intramuscular injection of the drug. It was possible to quantify this uptake by combining measurements of concentrations and flows. The administration of bupivacaine (0.75 mg/kg b.w.) did not result in any significant circulatory changes. Arterial bupivacaine concentrations showed major variations, indicating interindividual differences in absorption rate. Lung uptake after 10 min was high in two dogs with initially high blood concentrations of bupivacaine, but low after 20 min or longer. The other dogs showed little or no uptake. Mean hepatic bupivacaine uptake was about 50% of the total dose during the first hour after injection, this indicates the central role of the liver in eliminating bupivacaine even during the initial period following administration. The hepatic extraction ratio showed interindividual variations, but the mean value of about 55% was constant throughout the observation period. This is in agreement with earlier findings indicating a first-order elimination of bupivacaine.

Animals↗
PubMed1976

Decrease of oxygen consumption in the dog liver during temporary arterial occlusion.

The effects of occlusion of the hepatic artery on total and regional splanchnic oxygen consumption were studied in lightly anaesthetized dogs. Mean whole body oxygen uptake (+/- S.D.) was 4.72 +/- 0.55 ml/kg b.w. min-1, mean liver oxygen uptake (+/- S.D.) 1.18 +/- 0.42 ml/kg b.w. min-1 and mean oxygen uptake of the portally-drained tissues (+/- S.D.) was 0.80 +/- 0.54 ml/kg b.w. min-1 during the control period. The hepatic artery contributed 45 +/- 24% of the total liver oxygen uptake. The duration of occlusion was 45 min. Mean liver oxygen uptake was found to decrease to 64% of control values. The extraction of oxygen from the portal blood increased slightly. Mean whole body oxygen uptake and mean oxygen uptake of the portally-drained tissues were unchanged. 45 min after release of the hepatic artery occlusion, liver oxygen consumption had returned to control values. It is concluded that oxygen uptake in the liver is correlated to oxygen tension.

Animals↗
PubMed1975

Effect of controlled halothane anaesthesia on splanchnic blood flow and cardiac output in the dog.

Effects of halothane anaesthesia on aplanchnic blood flow and cardiac output were studied in six dogs. Blood flows in the hepatic artery, the superior mesenteric artery and the portal vein were measured electromagnetically. Cardiac output was measured by thermodilution. Depth of anaesthesia, ventilation, acid-base state and body temperature were controlled. Cardiac output and blood flows in the hepatic artery, the superior mesenteric artery and the portal vein decreased significantly to 73%, 54%, 59% and 60% of control values, respectively. Total peripheral vascular resistance decreased significantly, while mesenteric and portal resistance remained essentially unchanged and hepatic arterial resistance showed a significant increase. It is suggested that the difference between the various vascular responses may be caused by a differentiated release from baroreceptor inhibition in various parts of the bulbar vasomotor center.

Anesthesia, General↗
PubMed1975

The effect of controlled halothane anaesthesia on splanchnic oxygen consumption in the dog.

The influence of halothane ansesthesia on splanchnic oxygen flow and oxygen uptake was studied in seven dogs. Mean oxygen supply to the liver and the portally-drained tissues decreased significantly to 44% and 53% of control values, respectively, while mena oxygen consumption diminished insignificantly to 68% and 82% of control values, respectively. There was a fall in the oxygen flow/oxygen consumption ratio in all animals following halothane. The relatively unimpaired oxygen uptake, in spite of a diminished oxygen supply, led to an increased extraction of oxygen by the tissues. Some factors affecting oxygen utilisation during halothane anaesthesia are discussed.

Abdomen↗