Biomedical subjects

K F Aronsen

Publications and source records attributed to K F Aronsen.

At least 37 records · Page 2Linked to original sources

PubMed1980

Tissue perfusion and distribution of cardiac output during ketamine anesthesia in normovolemic rats.

Based on previous clinical experience, an anesthetic technique for the rat, using ketamine, has been evaluated. The method comprised an i.v. bolus injection of 30 mg/kg for induction and an i.v. continuous infusion of 1.5 mg/kg/min for maintenance of anesthesia. Minor differences in ketamine metabolism between man and the rat are discussed. It appears that a higher ketamine concentration at the receptor site was required in the rat as compared to man. During ketamine anesthesia in the rat, fractional distribution of cardiac output and regional tissue perfusion were determined with the aid of the microsphere method. The study showed increased fractions to the heart, brain and tongue. The carcass fraction was elevated shortly after induction but reduced during steady-state anesthesia. Stomach, bowel and kidneys received reduced fractions early, but after these fractions returned to their initial levels. As a consequence of the increased cardiac output, regional tissue perfusion was increased in practically all organs.

Anesthesia, Intravenous↗

PubMed1979

Results of hepatic lobectomy for primary epithelial cancer in 31 adults.

Hepatic lobectomy for primary epithelial cancer was performed in 31 adults from 1964 through 1977 in the surgical departments of six Scandinavian hospitals. Twenty-three patients were discharged and had a 2 year survival rate of 62 per cent and a 5 year survival rate of 16 per cent. Alternatives to surgery have not yet emerged. Further progress requires centralization.

Adenoma, Bile Duct↗

PubMed1979

Controlled blocking of hepatic artery flow with enzymatically degradable microspheres combined with oncolytic drugs.

A new method for intermittent hepatic arterial flow arrest has been used in combination with intraarterial 5-fluorouracil (5-Fu) for the treatment of secondary liver neoplasms in 12 patients. Polysaccharide microspheres with a half-life of 1 h were infused together with 5-Fu via a percutaneously introduced catheter into the hepatic artery. There were no significant side effects to the treatment. Clinical effects and overall survival were comparable to those of hepatic artery ligation.

Clinical Trials as Topic↗

PubMed1979

Evaluation of the microsphere method for determination of cardiac output and flow distribution in the rat.

The radioactive microsphere technique was applied to determine simultaneous cardiac output and flow distribution in the rat. Left ventricular injections of large numbers of microspheres were given, without significant adverse effects, allowing determination of flow to organs and tissues with low perfusion rates. In order to determine coronary blood flow it was necessary to excise the inner lining of the left ventricle, thus eliminating activity from deposits of microspheres. Cardiac output determination showed less variation with the sampling catheter in the abdominal aorta than in the femoral artery. It is concluded that the microsphere method can be conveniently used for hemodynamic studies in the rat, and that the abdominal aorta is the preferred site for the placement of the reference catheter in the rat.

Animals↗

PubMed1979

The mechanism of lysine-vasopressin hemostasis in bleeding esophageal varices.

The effect of vasopressin on the blood flow through experimentally induced esophageal varices and on the musculature of the lower end of the esophagus has been studied. The blood flow was measured by 85Kr injection into the portal vein and selective recording of the radioactivity of the blood flow through the varices. Simultaneous portography and recording of the portal and arterial blood pressure were performed. Following i.v. administration of vasopressin, there was seen a decrease in portal pressure and transient increase in arterial blood pressure. Simultaneously there was observed a decrease in blood flow through the varices, which were no longer visible at portography, while intra-esophageal pressure was increased. It is concluded that there is a dual mechanism of the effect of vasopressin on bleeding from esophageal varices. It reduces the portal pressure and it contracts the esophageal musculature with resultant compression of the afferent radicles to the submucosal esophageal varices.

Animals↗

PubMed1978

Haemostatic effect of triglycylvasopressin on bleeding from gastric mucosal lesions in the rat.

The haemostatic effect of triglycylvasopressin (TGLVP) on the gastric mucosa was evaluated in an experimental model in the rat. TGLVP was found to reduce the bleeding significantly compared with the untreated controls. The haemostatic effect was most prounounced and prolonged when 200 microgram/kg b.w. was given intravenously. The clinical application of this finding is discussed.

Animals↗

PubMed1978

Studies in pharmacokinetics and tolerance of substances temporarily retained in the liver by microsphere embolization.

Earlier investigation has shown that a temporary arrest of arterial blood flow can be achieved by embolization with degradable microspheres. This study was made to investigate the change in pharmacokinetics, and drug tolerance which takes place when a substance is retained in the liver by a microsphere embolization. 14C-labelled inulin and 5-fluorouracil were studied. The administration of these substances with microspheres led to a delay in their systemic distribution. Furthermore there was an increased tolerance to 5-fluoro-uracil, probably due to a prolonged first pass effect when the substance was temporarily retained in the liver by a microsphere embolization.

Animals↗

PubMed1978

Hemodynamics during superficial thiopental anesthesia in the dog.

Radioactive microspheres, labeled withe ytterbium (169Yb), strontium (85Sr) and cerium (141Ce) were used in an investigation of the cardiovascular response to superficial thiopental anesthesia. The course was followed for 90 min and measurements were carried out 30, 60 and 90 min, respectively. Between 30 and 60 min of anesthesia there was a slight decrease in cardiac output and left ventricular work. The blood flow was reduced to the lungs, kidneys and the liver. Between 60 and 90 min there were, except for the coeliac artery and total liver, no further changes, which indicated a circulatory steady state.

Anesthesia, Intravenous↗

PubMed1978

The hemodynamic effect of halothane in the normovolemic dog.

With the aid of radioactive microspheres (labeled with 169Yb, 85Sr and 141Ce, respectively), the effect of halothane anesthesia on circulation was studied for 30 min and (group A) for 120 min of halothane anesthesia in thiopental-sedated dogs. Measurements were also carried out on recovery from halothane anesthesia. Besides such well-known general circulatory changes as reduction in cardiac output, pulse rate, left ventricular work, arterial mean blood pressure and left atrial mean blood pressure, in both groups there was also a reduced coronary blood flow. The flow to the lungs, kidneys and the brain was well preserved, despite the reduction in both the cardiac output and arterial mean blood pressure. The flow to the liver, however, did not change during short halothane anesthesia; but during long anesthesia there was a marked reduction, due mainly to a decrease in the flow to the preportal area. On recovery from halothane anesthesia, the changes had mostly returned to the preanesthetic values.

Anesthesia, Inhalation↗

PubMed1978

The effect of halothane on the distribution of cardiac output and organ blood flow in the hypovolemic dog.

The circulatory effect of halothane anesthesia given to moderately hypovolemic dogs (blood loss 25 ml/kg b.w.) was investigated using the radioactive microsphere technique. The effect of the anesthetic was reflected by a decrease in the arterial mean blood pressure and a reduced blood flow to the heart, whereas the blood flows to other organs did not change significantly but were well preserved in vital organs (brain, kidneys, liver and lungs). The effect on the circulation of reinfusing the withdrawn blood was also studied.

Anesthesia↗

PubMed1978

The effect of halothane on the distribution of cardiac output and organ blood flows in the hemorrhagic, hypotensive dog.

Halothane was given to dogs which had been bled to an arterial mean blood pressure of 60 mmHg, and the circulatory effects were studied with the aid of the radioactive microsphere technique. The cardiac output and coronary blood flow were well maintained, whereas the arterial mean blood pressure was slightly, and the stroke volume markedly increased, indicating an improved heart function. The blood flows to the brain, lungs, liver and kidneys were well preserved throughout the anesthesia. The effect of retransfusing the withdrawn blood was also studied, and it resulted in an increased cardiac output, arterial mean blood pressure and increased blood flows to the heart, lungs, spleen, bowel and liver.

Anesthesia↗

PubMed1978

Distribution of cardiac output in burned mice after treatment with triglycylvasopressin.

Earlier published results have shown an increased 5-day survival in burned mice treated with Triglycylvasopressin. In order to analyze the cause of the increased survival, the distribution of cardiac output was studied in 51 mice divided into three groups. The investigation was performed on the 5th day after burn using a soluble indicator technique (86Rb). The first group consisted of unburned animals. In the second and third groups, a standardized burn of 15% of the body surface was undertaken. The animals in the second group were used as controls and received isotonic saline solution for 5 days. The third group were used as controls and received isotonic saline solution and in addition Triglycylvasopressin, a vasopressin with prolonged effect, 100 microgram/kg body weight subcutaneously twice a day in such a way that the total volume of fluid was identical in the different groups. Cardiac output distribution showed an increased fraction to kidney, liver and small bowel and a decreased fraction to carcass in the Triglycylvasopressin-treated animals compared to burned controls.

Animals↗

PubMed1978

Effect of the calcium antagonist nifedipine on uterine blood flow in non-treated and oestradiol-treated rats.

Organ blood flow, as estimated by the radioactive labelled microsphere technique, was studied in rats before and after intracaval administration of the calcium antagonist nifedipine. Intra-uterine and arterial blood pressures were registered simultaneously. Two groups of animals were investigated, one non-treated and one treated with oestradiol. After administration of nifedipine, an increase in the blood flow to the brain, the heart and the kidneys was seen in both groups of animals. However, in the uterus, blood flow was markedly increased in non-treated, but not so in oestradiol-treated animals. The arterial blood pressure and intra-uterine pressure were almost unaffected. The results suggest that nifedipine can markedly increase blood flow to the uterus of non-oestrogen-treated rats with only minor effects on intra-uterine and arterial blood pressures.

Animals↗

PubMed1977

Evaluation of catheter-manometer systems for adequate intravascular blood pressure measurements in small animals.

Various catheter-manometer systems possible for intravascular blood pressure measurments on rats have been elaborated and tested in vitro and in vivo. Using a pressure-step calibrator, it was observed from in vitro studies that microtransducers had superior frequency response compared to conventional transducers. Of the catheters tested, Pe-90 tapered to a 40 mm tip with an inner diameter of 0.3 mm had the best frequency response as judged from fall and settling times. Because of the damping effect, tapering increased fall time to 1.8 ms, which was still quite acceptable. By the same token settling time was minimized to 22.4 ms. With a special calculation method the theoretical percentile fault of the recordings was estimated to be 9.66%. When the measurement error was calculated from the actual in vivo recordings, it was found to be no more than 2.7%. These results show that the technique described is adequate for continuous intravascular blood pressure recordings on small animals. Finally it is emphasized that careful handling of the catheters and avoidance of stopcocks and air bubbles are essential for obtaining accurate and reproducible values.

Amplifiers, Electronic↗

PubMed1977

The circulation in liver tissue and experimental liver metastases before and after embolization of the liver artery.

Simultaneous measurement of cardiac output distribution with 86Rubidium and 57Cobalt-tagged microspheres in rats implanted with liver tumors by intraportal injection of sarcoma cells enables quantitation of arterial and portal tumor circulation. The portal circulation was found to be increased in small tumors as compared to the liver, but as the tumor grew there was a decrease in the portal tumor circulation. When the tumor growth became massive even the total liver circulation was reduced, as measured with 133Xenon wash-out. All the tumors had increased arterial circulation. This arterial hyperperfusion was changed into ischemia when the liver artery was occluded through embolization with degradable microspheres.

Animals↗

PubMed1977

Microsomal hexobarbital metabolizing enzymes in regenerating cholestatic rat liver.

Microsomal changes were studied in regenerating liver cholestatic rats by measuring hexobarbital metabolzing capacity (HMC) in vitro. Total extrahepatic biliary obstruction was induced by ligating the common duct, 3 days later, a 70% liver resection was performed. Sham-operated animals served as controls. Analysis of HMC showed a similar pattern of microsomal regeneration in cholestatic as in sham-operated rats. This indicates that in the rat, cholestasis per se does not interfere with the development of this enzyme system during regeneration.

Alkaline Phosphatase↗

PubMed1977

Repeated arterial embolization of rat livers by degradable microspheres.

A transient arrest of arterial blood flow can be accomplished by intra-arterial injection of a new type of degradable microsphere. The effects of single and multiple injections of these microspheres into rat hepatic arteries were studied by measurements of fractional cardiac output distribution and 133Xe washout from the liver before and after embolization. Injection of these microspheres into the hepatic artery caused a significant but transient reduction of the arterial blood flow to the liver. Repetition of the injection several times over several days produced identical effects on each embolization. No signs of hepatic cell damage were detected after repeated embolization, as suggested by assay of the serum enzymes or the Bromsulphalein retention test.

Animals↗

PubMed1977

Changes in cardiac output distribution after liver dearterialization in the rat.

The changes in cardiac output distribution in rats have been studied after hepatic artery ligation and additional ligament division. These procedures resulted initially in a marked decrease in the arterial blood supply to the liver and this effect was pronounced still four weeks after the operation. Evidence was found that the decrease in liver blood supply induced by the procedure was in part counterbalanced by arteriovenous shunting in the preportal region. Furthermore, a temporary redistribution of cardiac output with reduced fractions to colon and spleen was found two weeks after these operations.

Animals↗