Biomedical subjects

L Irestedt

Publications and source records attributed to L Irestedt.

61 records · Page 4Linked to original sources

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

Blood circulation in the kidney of the cat under methoxyflurane (penthrane) anaesthesia.

In order to establish whether methoxyflurane causes any change in renal vascular resistance, the renal venous flow was measured by means of a drop recording technique in six cats under methoxyflurane anaesthesia. Arterial pressure was recorded simultaneously, and the renal vascular resistance was calculated. Methoxyflurane caused a significant reduction of the renal vascular resistance to about 85% of control value at an anaesthetic depth characterised by loss of the corneal reflex. At a deeper anaesthetic stage characterised by steady state circulation and absence of any reflexes, no further significant fall in renal vascular resistance occurred. Autoregulation and depression of the sympathetic activity are assumed to explain the reduction of the renal vascular resistance.

Anesthesia, Inhalation↗

PubMed1975

Concentration of bupivacaine in arterial and venous plasma after epidural anaesthesia in man and after intramuscular administration in dog.

The arteriovenous concentration difference of bupivacaine in plasma after epidural injection in man and after intramuscular injection in dog was studied. In man, arterial concentration was higher than peripheral venous ocncentration during an initial period of about 30 min, after which time period venous and arterial concentrations became fairly similar. Comparable results were obtained in the animal experiments. In addition, the experiments in dog indicated that the concentration of bupivacaine was fairly similar in central venous plasma and arterial plasma, but higher than the peripheral venous plasma concentration. These factors have to be taken into consideration when toxicological studies of local anaesthetic drugs are made.

Adult↗

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↗