Search PubMed⌕ Search

Biomedical subjects

G J Benson

Publications and source records attributed to G J Benson.

At least 73 records · Page 4Linked to original sources
PubMed1982

Organ blood flow and distribution of cardiac output in nonanesthetized swine.

Organ blood flow and distribution of cardiac output (CO) were determined in awake resting swine, using radionuclide-labeled 15-micrometer diameter microspheres. Absolute values of blood flow (per 100-g basis) were determined for various organs and peripheral tissues. Internal organs of the swine, which constituted 8.25 +/- 0.79% of the total body mass, received 45.46 +/- 2.64% of the resting CO. The fraction of CO received by brain, heart, kidneys, liver (via hepatic artery), and gastrointestinal tract was 1.13%, 3.04%, 12.95%, 4.27%, and 18.71%, respectively.

Animals↗
PubMed1981

Effects of sodium acetate, bicarbonate and lactate on acid-base status in anaesthetized dogs.

Equal doses of sodium acetate, bicarbonate and lactate (6.6 mEq/L) infused intravenously over 30 min into three groups of halothane-anaesthetized dogs caused changes in acid-base status. Arterial carbon dioxide tension (PaCO2), pHa, base excess (BE) and standard bicarbonate (SB) increased. Sodium bicarbonate caused the most rapid and greatest changes. The bicarbonate group was significantly different (P less than 0.05) from the other groups at 15 and 30 min after the start of infusion for pHa, BE and SB. The greater effects of bicarbonate are due to its production of alkalinization without a requirement for metabolism; acetate and lactate require oxidation to be effective. The acetate and bicarbonate groups were not statistically different at 45 min after the onset of drug infusion, but both had significantly higher SB and BE mean values than the lactate group. All measurements made after 45 min revealed no significant differences among groups. Thus, after the earlier differences noted above, the three alkalinizers caused similar effects on acid-base status. PaCO2 was elevated in all groups, but there were no differences among groups. Cardiovascular effects caused by infusion of the three drugs were minimal.

Acetates↗
PubMed1981

Surgical technique and considerations for implantation of electromagnetic blood flow transducer and occluder onto the coronary arteries.

A technique was developed for the implantation of an electromagnetic flow probe and vascular occluder onto the right and left coronary arteries in the calf and pony. Surgical manipulation was well tolerated in the animals. The subcutaneous housing on the peripheral ends of these devices of the lateral thoracic wall served as a maintenance-free technique for chronic exteriorization of these devices. Implantation onto the coronary arteries required a surgical technique which accomplished the prerequisites for proper flow probe function. A reactive hyperemic response was elicited in each animal by implanting an inflatable vascular occluder distal to the flow probe. The correct function of these devices postoperatively established the feasibility of this surgical technique for implanting these devices on the coronary arteries for chronic studies of coronary circulation.

Animals↗
PubMed1980

Biochemical effects of succinylcholine chloride in mechanically ventilated horses anesthetized with halothane in oxygen.

Succinylcholine chloride administered to horses anesthetized with halothane in oxygen and mechanically ventilated, caused slight but statistically insignificant (P less than 0.01) increases in creatine phosphokinase, lactic dehydrogenase, and aspartate aminotransferase activity. The increases in these enzymes have been explained on the basis of muscle damage resulting from succinylcholine chloride induced muscle fasciculations and by hypoperfusion of tissues due to depression of the cardiovascular system caused by general anesthesia. These changes were not clinically apparent based upon the absence of myoglobinuria and ease of recovery. There was no significant effect of treatment observed on other biochemical variables. The findings in the present study agree with previous observations on serum creatine phosphokinase, lactic dehydrogenase, and aspartate aminotransferase activity.

Alanine Transaminase↗
PubMed1979

Spinal analgesia and sedation of goats with lignocaine and xylazine.

Spinal anaesthesia of 20 does undergoing laparotomies was accomplished with epidural injections of 2 per cent lignocaine at a dosage of 1 ml per 4.55 kg in 16 goats. Epidural injection resulted in paralysis lasting 198.5 minutes +/- 36.6 minutes. Subarachnlid injection resulted in paralysis lasting 180.8 minutes +/- 44.9 minutes. Xylazine was given intramuscularly at the dosage of 0.11 mg per kg after posterior paralysis was complete. These treatments resulted in effective analgesia for surgical intervention. Recovery was complete and uneventful in all goats. An additional 26 operations were performed using this treatment and results were equally satisfactory.

Analgesia↗
PubMed1979

Physiologic effects of succinylcholine chloride in mechanically ventilated horses anesthetized with halothane in oxygen.

Succinylcholine chloride, administered to horses anesthetized with halothane in oxygen and mechanically ventilated, caused slight but significant (P less than 0.01) increases in heart rate. Significant alteration in mean arterial blood pressure did not occur, and there were clinically insignificant increases in serum K+ and C1- concentration. Cardiac dysrhythmia and myoglobinuria did not occur. Thus, effects of halothane anesthesia and mechanical ventilation prevented cardiac dysrhythmia and hypertension and greatly reduced the tachycardia generally associated with siccinylcholine administration.

Anesthesia, Inhalation↗
PubMedDate not supplied

The hemodynamic response of calves to tiletamine-zolazepam anesthesia.

Six isoflurane-anesthetized calves were instrumented for hemodynamic studies and allowed to recover from anesthesia. When the mean arterial blood pressure rose to 100 mmHg or when vigorous movement occurred, a 1:1 tiletamine-zolazepam mixture (4 mg/kg) was administered intravenously (IV). Values for cardiac output, cardiac index, stroke index, central venous pressure, and right ventricular stroke work index did not change significantly. Systolic, mean, and diastolic arterial blood pressures and systemic vascular resistance were significantly decreased below baseline at 5 minutes; they were significantly increased above baseline at 20 minutes and remained so throughout the 60 minute study. Changes in left ventricular stroke work index and rate pressure product were similar to those of arterial blood pressure and systemic vascular resistance, although they were not significant. Heart rate and pulmonary capillary wedge pressure decreased significantly but gradually returned to baseline at 40 minutes and then increased significantly above baseline by the end of the study. Minor venous-arterial shunting or perhaps mismatching of ventilation and perfusion appeared to have developed in the later stages of the study. This was reflected in a minor increase in the arterial partial pressure of carbon dioxide (PaCO2) and a decrease in the arterial partial pressure of oxygen (PaO2) and arterial pH. At the dose administered, the hemodynamic changes induced by tiletamine-zolazepam were minimal and were compatible with safe anesthesia in calves.

Anesthesia↗
PubMedDate not supplied

Evaluation of three midazolam-xylazine mixtures. Preliminary trials in dogs.

The depressant effects of midazolam and xylazine on the central nervous system (CNS) were evaluated in 12 dogs. Xylazine was administered to six dogs (1.1 mg/kg intravenously [IV]) followed in 5 minutes by midazolam (1.0 mg/kg intramuscularly [IM]). In a second group of six dogs, xylazine (2.2 mg/kg IM) was followed in 5 minutes by midazolam (1.0 mg/kg IV). Both drug regimens induced rapid and profound sedation or anesthesia. Duration of action varied with the doses and routes of administration. Dogs given the high dose of xylazine IM had an arousal time of 95.4 +/- 8.9 minutes and a walking time of 155.4 +/- 8.8 minutes. These values exceeded the IV xylazine values threefold. Partial reversal of CNS depression was accomplished with either a benzodiazepine antagonist (flumazenil) or an alpha-2 antagonist (yohimbine). In a separate trial, a mixture of xylazine (0.55 mg/kg), midazolam (1.0 mg/kg), and butorphanol (0.1 mg/kg) with and without glycopyrrolate was evaluated in eight dogs. As with the xylazine-midazolam combinations, the CNS depressant effect of this mixture was clinically indistinguishable from anesthesia achieved with other rapid-acting injectable agents. Clinical signs of CNS depression were readily and completely antagonized by the simultaneous injection of flumazenil and yohimbine.

Anesthesia↗
PubMedDate not supplied

Hemodynamic effects of intravenous midazolam-xylazine-butorphanol in dogs.

The hemodynamic effects of a mixture of midazolam (1.0 mg/kg), xylazine (0.44 mg/kg), and butorphanol (0.1 mg/kg) were evaluated in six adult dogs. The dogs were anesthetized with isoflurane for instrumentation. As the dogs returned to consciousness, baseline values were recorded and the midazolam-xylazine-butorphanol mixture and glycopyrrolate (0.01 mg/kg) were administered intravenously (IV). Hemodynamic data were recorded 3, 10, 20, 30, 40, 50, and 60 minutes after injection. Mean arterial pressure (AP), mean pulmonary arterial pressure (PAP), heart rate (HR), rate-pressure product (RPP), mean pulmonary capillary wedge pressure (PCWP), systemic vascular resistance (SVR), and right ventricular stroke work index (RVSWI) were increased significantly above baseline values. Cardiac output (CO), stroke volume (SV), cardiac index (CI), stroke index (SI), mean central venous pressure (CVP), and left ventricular stroke work index (LVSWI) were decreased significantly below baseline values. When administered IV at the dosages used in this study, midazolam-xylazine-butorphanol-glycopyrrolate induced profound acute alterations in several critical hemodynamic variables.

Animals↗
PubMedDate not supplied

Postoperative catecholamine response to onychectomy in isoflurane-anesthetized cats. Effects of analgesics.

Twenty-four healthy adult cats were anesthetized with isoflurane in oxygen. Six cats (group 1) served as controls; onychectomy of the forefeet was performed in the other three groups. Saline was administered intravenously to group 1, and morphine, xylazine, and salicylate were administered to groups 2, 3, and 4, respectively. Mixed venous blood samples were drawn for catecholamine analysis before induction of anesthesia, after recovery from anesthesia, and 30 minutes and 60 minutes after administration of the analgesic agent. Plasma catecholamine concentrations were determined by high performance liquid chromatography. Isoflurane anesthesia alone induced a transient increase in epinephrine concentration. Norepinephrine and epinephrine concentrations increased significantly after onychectomy. Morphine and xylazine significantly decreased postoperative norepinephrine and epinephrine concentrations; salicylate did not.

Analgesics↗