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Biomedical subjects

S Gelman

Publications and source records attributed to S Gelman.

At least 91 records · Page 5Linked to original sources
PubMed1984

Clearance of 9-micron spheres and rubidium in the intestinal circulation.

Rubidium clearance and 9-micron-sphere entrapment were studied and compared in isolated intestinal preparations under various physiological conditions in 10 dogs anesthetized with intravenous pentobarbital sodium. The chosen intestinal segment was pumped with aortic blood at a constant rate and pressure of about 90-100 mmHg. The temperature of the isolated loop was maintained at 37-38 degrees C with an electrical pad. A mixture of 86Rb and 9-micron-spheres labeled with 141Ce was injected into the arterial cannula supplying the intestinal loop while mesenteric venous blood was collected for activity counting. Three to four intestinal segments were used from each dog. The following three experimental conditions were randomly used for each intestinal segment preparation: 1) a mesenteric venous pressure (MVP) equaling 0 cmH2O and warmed normal saline infused into the lumen of segment; 2) an MVP equaling 0 cmH2O and 5% glucose in saline infused into the intestinal lumen; and 3) the reservoir with venous blood elevated to provide an MVP equaling 17 cmH2O and warmed normal saline infused into the intestinal lumen. A very strong and significant correlation was found between rubidium and microsphere clearances (r = 0.99, P less than 0.0001). Rubidium extraction was inversely associated with blood flow through the intestinal segment (r = 0.49, P = 0.02), while microsphere entrapment (extraction) was independent from intestinal blood flow (r = 0.16). The data suggest that the shunting of 9-micron spheres through tissue reflects the arteriovenous shunting of blood and, therefore, can be used as a tool to study the nutritive and nonnutritive blood flows in tissues.

Animals↗
PubMed1984

Correlation of cerebral blood flow and EEG during carotid occlusion for endarterectomy (without shunting) and neurologic outcome.

One hundred twenty-nine consecutive carotid endarterectomies performed for atherosclerotic ulcerative stenosis without the use of intraoperative shunting were analyzed prospectively in an effort to determine the significance of intraoperative ischemia. Intraoperative EEG and regional cerebral blood flow measurements were used to monitor these patients. Ten of the patients were excluded because of inadequate data, but none of these 10 patients experienced a complication. Factors analyzed included preoperative risk assessment according to the Mayo Clinic system of Sundt et al., intraoperative regional cerebral blood flow measurements, and intraoperative EEG changes. The overall mortality rate was 2.5%, the major morbidity rate was 2.5%, the minor morbidity rate was 1.7%, and the rate of transient neurologic dysfunction was 1.7%. The patients' preoperative state as determined according to the Mayo Clinic system of Sundt et al. was more useful in identifying patients at risk than was intraoperative EEG and regional cerebral blood flow monitoring.

Anesthesia, General↗
PubMed1984

The effect of halothane, isoflurane, and blood loss on hepatotoxicity and hepatic oxygen availability in phenobarbital-pretreated hypoxic rats.

This study evaluated the role of ventilatory and circulatory depression in anesthesia-induced hepatotoxicity in rats. Male Sprague-Dawley rats (181 animals) were pretreated with phenobarbital and exposed to hypoxia (FIO2 = 0.14) for 2 hr. The animals were divided into four groups: group 1 received 1% inspired halothane in the hypoxic gas mixture; group 2 received 1.4% inspired isoflurane and hypoxia; group 3 had 25-30% of their blood volume removed 2 hr before exposure to hypoxia; and group 4 served as a control with no treatment other than hypoxia. Hepatic blood flow was studied using microspheres; oxygen availability to the liver was calculated using values of hepatic blood flow and oxygen content of arterial and portal venous blood; and liver injury was quantitatively evaluated. Ventilation was depressed in rats that received halothane and, to a lesser extent, isoflurane. The lowest portal blood flow was observed in groups 1 and 3. Hepatic arterial blood flow was lowest in group 1 and highest in group 3. There was an inverse relationship between hepatic oxygen availability and severity of histologic lesions. The most severe lesions and lowest oxygen availability was associated with halothane. Hemorrhage and isoflurane were associated with less diminution of oxygen availability and less severe hepatic lesions. The least decrease in oxygen availability and the least severe histologic changes occurred in control rats subjected to hypoxia only.

Animals↗
PubMed1984

Regional blood flow during isoflurane and halothane anesthesia.

Cardiac output distribution and regional blood flow in 18 dogs during isoflurane and halothane anesthesia were studied in dose-related fashion. Surgical preparation consisted of left thoracotomy and placement of catheters in the left atrium and aorta through a femoral artery. Regional blood flow was studied one week after surgical preparation using a microsphere technique at the three stages: awake, 1 MAC, and 2 MAC of inhalation anesthesia. At each stage of the experiment, two sets of microspheres (15- and 9-micron diameter), labeled with different isotopes, were used simultaneously. Both anesthetics increased cerebral blood flow, decreased blood flow through preportal area, and preserved renal blood flow. Isoflurane increased hepatic artery blood flow at both levels of anesthesia, while halothane preserved the flow during 1 MAC and decreased it at 2 MAC. Apparently, isoflurane provided better oxygenation to the liver than halothane. Myocardial blood flow was increased during isoflurane (despite decrease in blood pressure and cardiac output) and decreased during halothane anesthesia. Isoflurane appears to be a coronary vasodilator with potential beneficial (improvement in myocardial blood supply) as well as hazardous ("steal effect") effects on the heart.

Animals↗
PubMed1983

Regional blood flow during cross-clamping of the thoracic aorta and infusion of sodium nitroprusside.

Labeled microspheres, 15 microns in diameter, were used to determine cardiac output and regional blood flow response to cross-clamping of the midthoracic aorta and subsequent sodium nitroprusside (SNP) infusion in 11 dogs. During aortic cross-clamping, mean arterial pressure above the occlusion (MAPa) increased 30% to 35%, mean arterial pressure below the occlusion (MAPb) decreased 87%, cardiac index decreased 12% to 14%, left atrial pressure (LAP) doubled, and renal and spinal cord (lower part) blood flows decreased substantially (85% to 94%). SNP infusion returned MAPa to baseline values, decreased MAPb by half, and substantially and further decreased renal blood flow (to 3% to 5% of baseline values). Myocardial and cerebral blood flows increased substantially (up to 250% to 400%). An increase in preload (fluid load) was accompanied by an increase in LAP, cardiac index, and myocardial blood flow only but not in renal or spinal cord flow. There was a strong association between cortical renal blood flow and MAPb (r2 = 0.92; p less than 0.0001), which suggests that blood flow through organs and tissues below the occlusion is pressure dependent. The data show that SNP infusion during thoracic aortic cross-clamping improves systemic and regional circulation above the occlusion but decreases MAPb and therefore blood flow below the occlusion. SNP infusion should be used with caution during aortic cross-clamping, since arterial hypotension of any degree may be deleterious to organs below the cross-clamp.

Animals↗
PubMed1983

Circulatory responses to midazolam anesthesia: emphasis on canine splanchnic circulation.

Experiments were performed on nine dogs instrumented with pulmonary artery Swan-Ganz catheters and catheters placed into the distal aorta and posterior caval vein. Electromagnetic flowmeter probes were placed around the portal vein and hepatic artery, and the portal vein was cannulated. A week later, systemic and splanchnic circulatory variables were studied before and after 10 mg/kg of midazolam given intravenously. Three minutes after injection, heart rate increased 26% (P less than 0.006), cardiac index decreased 15% (P less than 0.001), portal flow increased 19% (P greater than 0.05), and hepatic arterial flow decreased slightly (P less than 0.002). Later, portal blood flow decreased 17% below baseline values (P less than 0.006). The biphasic response of portal blood flow to midazolam is probably related to redistribution of blood within the splanchnic system (blood mobilization from spleen and intestine). It is suggested that because maintenance of cardiac output during midazolam anesthesia depends on compensatory mechanisms, failure to increase cardiac output with compensatory increases in heart rate, contractility, and blood volume mobilization from the splanchnic circulation could result in decreased cardiac output.

Anesthesia, Intravenous↗
PubMed1982

Prediction of the needed level of sympathectomy for posttraumatic reflex sympathetic dystrophy.

The course of 2 patients with posttraumatic reflex sympathetic dystrophy is presented and discussed. The importance of determining the exact level of sensory blockade in order to know the necessary level of the sympathectomy is emphasized. It is suggested that in patients with reflex sympathetic dystrophy, the diagnosis should include the exact upper anatomical level of sympathetic truncus involvement, which can be easily achieved with sensory epidural blockade.

Adolescent↗
PubMed1980

Thoracic epidural vs balanced anesthesia in morbid obesity: an intraoperative and postoperative hemodynamic study.

Thirty-eight morbidity obese patients undergoing gastric bypass were divided into two groups. All patients received general endotracheal anesthesia with muscle relaxation and controlled respiration with N2O-O2 mixture. In addition, group I, 17 patients, received balanced anesthesia, while the remaining 21 patients, group II, received thoracic (T-5) epidural analgesia. Postoperative analgesia was achieved with morphine intravenously in group I and with 0.5% bupivacaine epidurally in group II. Circulatory function was measured and calculated using radial artery cannulation and pulmonary artery catheterization with Swan-Ganz thermodilution catheters. A significant decrease in cardiac index (10% and 14% in groups I and II, respectively), in left and right ventricular stroke work (12% to 30%), systolic blood pressure-heart rate product (16% and 28% in groups I and II, respectively), in arterial venous oxygen content difference and oxygen consumption (31% and 39% in groups I and II, respectively) was observed during surgery. A decrease in intrapulmonary shunt from 20% +/- 2.9% before anesthesia to 15% +/- 2.1% intraoperatively was seen in patients given epidural anesthesia. Postoperatively epidural analgesia was associated with a decrease in left ventricular stroke work 12%), systolic pressure-heart rate product (10%), arteriovenous oxygen content differences (17%), and oxygen consumption (20%), compared with values observed when patients experienced pain. Morphine given for relief of postoperative pain was not associated with significant changes in cardiovascular function. Continuous epidural analgesia used postoperatively for relief of pain in morbidity obese patients, following upper abdominal surgery, slightly decreases oxygen requirement and benefits cardiovascular function as reflected by a decrease in left ventricular stroke work.

Adult↗
PubMed1978

Nitroprusside prevents adverse hemodynamic effects of vasopressin.

The influence of vasopressin and sodium nitroprusside on liver circulation was investigated in 18 dogs. Cardiac output was determined by the thermal dilution technique using a Swan-Ganz catheter. Hepatic artery and portal vein flows were measured with electromagnetic flowmeters. The infusion of vasopressin (0.01 unit/kg/min) caused a 13% increase in mean arterial pressure, a 38% decrease in cardiac output, a 57% decrease in portal blood flow, and a 35% decrease in portal pressure. Hepatic artery blood flow initially decreased, then increased, and eventually exceeded the baseline value by 25%. The addition of sodium nitroprusside infusion (10 microgram/kg/min) returned the mean arterial pressure to baseline value and increased cardiac output to 83% of baseline value. Portal blood flow remained unchanged, even though an additional decrease in portal pressure of 11% and a further increase in hepatic artery blood flow of 45% were observed. Nitroprusside minimizes the undesirable effects of vasopressin and augments the desirable ones in normal dogs. The combination of these drugs may be more beneficial to patients with esophageal and gastrointestinal bleeding than vasopressin alone.

Animals↗