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Query: UMLS:C0278134 (anesthesia)
 110,339 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A number of physiopathogenic mechanisms have been outlined to explain the "infarct-like" lesions produced by isoproterenol (ISP) in the hearts of various animals: Excess of oxygen consumption and inotropic effect, coronary vasoconstriction, deleterious action on glucose and lipid metabolism, direct cardiotoxic effect, platelet aggregation in the small cardiac vessels and formation of microclots, excessive mobilization of fatty acids, fluid and electrolytic imbalances, loss of high-energy intracellular coupling, and inadequate activation of the "calcium pump." For this reason, localization of the tritiated ISP in the normal myocardial fibers and in the induced lesions was studied. The first control group (G-1), consisted of 40 Wistar rats, weighing from 180 to 200 grams; they were injected intraperitoneally with ISP sulfate (10 mg. per kilogram) and were killed under ether anesthesia after periods of 5, 30, and 120 minutes, and 12 and 24 hours. A similar group (G-2) was injected intraperitoneally with an equal dose of ISP plus 5 muCi of tritiated ISP sulfate (3H). In this group animals were killed at the same periods as above. In rats treated with ISP-3H an abundant amount of the labeled drug was observed on the sarcolemma surface and a smaller quantity was noted inside the myocardial fibers. This observation was noted in the autoradiographs obtained 5 minutes after the injection and persisted in all subsequent observation times. In those animals which were killed 5 and 30 minutes after injection, the deposit was noted in "grooves" along the edge of the sarcolemma, strongly suggesting a primary action on the cellular membrane. These findings and the peculiar topography suggest that (1) myocardial necrosis induced by ISP is probably due to an increased activation of the "calcium pump"; the early presence of contracture bands and the positivity of the ischemia test further emphasize this statement; (2) the ISP effect is rapid; (3) the morphologic alterations are similar to those recently described as "coagulation myocytolysis" and present in human infarctions or following sudden death.
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PMID:Localization by autoradiography of tritiated isoproterenol in "infarct-like" lesions of rat myocardium. 94 29

In experiments on cats and dogs under general anesthesia nonachlazine, a new antianginal agent, depressed the reflex decrease of the blood flow to the coronary arteries (electromagnetic recording). Nonachlazine also depressed the reflex decrease of the blood flow in the system of common carotic artery, and the pressure vasomotor reflexes. During recording the tonic and reflex activity in the heart sympathetic nerves nonachlazine proved to selectively inhibit the vasoconstrictor impulses from Adelta-afferent fibers of the spinal nerves, that is it influenced the vasomotor component of the "primary" pain reaction. This mechanism could underlie the block by nonachlazine of the pain syndrome during the heart ischemia disease.
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PMID:[Mechanism of action of nonachlazin on nervous regulation of coronary circulation]. 95 79

The effect of halothane on net myocardial oxygen balance of ischemic myocardium was studied in the non-failing canine heart. Myocardial ischemia was produced by repeated reversible occlusions of a coronary artery; the severity of ischemia was estimated by summating ST-segment elevations (sigma ST) obtained by epicardial ECG mapping at 15 to 18 sites. Control measurements were obtained before and after administration of halothane (0.75 per cent) to six dogs with chloralose-urethane basal anesthesia. Halothane was associated with significant decreases of systemic arterial pressure (P less than .001), heart rate (P less than .01), and the product of systolic arterial pressure X heart rate (P less than .01), an indirect index of myocardial oxygen consumption, while left atrial pressure remained unchanged at normal levels. sigmaST during occlusion was less (P less .001) during halothane (26.5 +/- 7.4 (SD) mv) than before (36.6 +/- 5.4 mv) or after (34.4 +/- 8.2 mv) its administration. Thus, halothane decreased the severity of experimentally-induced myocardial ischemia in the non-failing canine heart. The data suggest that, in the absence of ventricular failure, halothane influences the relationship between myocardial oxygen supply and demand in a favorable direction when coronary blood flow is limited.
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PMID:Halothane-induced decrease in experimental myocardial ischemia in the non-failing canine heart. 96 78

In tests set up on dogs under morphine-chloralose anesthesia features specific for upset cardio- and hemodynamics following a primary and repeated (against the background of a preliminarily provoked myocardial infarction) acute disruption of the coronary circulation were investigated. The development of an acute ischemia of the myocardium in animals with preliminarily induced chronic disruption of the coronary circulation was shown to be attended by more intensive than in healthy dogs hemodynamic shifts and functional disorders of the heart, whereas the reflex component of the reaction, the vasodilating reactions of the peripheral vessels, in particular, proved much less marked. Possible mechanisms accounting for differences in the derangement of the cardio- and hemodynamics in primary and repeated ischemia of the myocardium are discussed.
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PMID:[Study of the relation between cardiac function and the tonus of resistant vessels in experimental disorder of coronary circulation]. 96 33

Carotid endarterectomy requires temporary surgical occlusion of the involved carotid artery. During occlusion, the minimally acceptable (critical) internal carotid artery stump pressure is reported to be 50 torr, whereas for regional cerebral blood flow (rCBF), a critical range is reported to be 18-24 ml/100 g/min. During 90 carotid endarterectomies, rCBF and stump pressure were measured and the EEG continuously monitored. A positive correlation between rCBF and stump pressure (i.e., when both were either above or below their respective critical values) was observed in only 58 per cent of the cases. In 28 per cent stump pressures of less than 50 torr were observed despite rCBF's above 24 ml/100 g/min and normal EEG's. In 8 per cent stump pressures were more than 50 torr but rCBF's were less than 18 ml/100 g/min and EEG changes of ischemia were commonly observed. In the remaining 6 per cent rCBF's were marginal (18-24 ml/100 g/min) while stump pressures were more than 50 torr and EEG changes were not observed. The relationship between stump pressure and rCBF was influenced by the anesthetic. In the absence of transient ischemia during occlusion (that is, rCBF greater than 18 ml/100 g/min), halothane and enflurane anesthesia were associated with significantly higher rCBF's and lower stump pressures than was neuroleptanesthesia. Pre-occlusion and post-occlusion rCBF measurements also demonstrated cerebral vasodilation by halothane and enflurane (halothane greater than enflurane) and vasoconstriction by neuroleptanesthesia. It is concluded that stump pressure is an unreliable index of CBF during carotid occlusion and that its relationship to CBF is considerably influenced by the anesthetic.
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PMID:Internal carotid artery stump pressure and cerebral blood flow during carotid endarterectomy: modification by halothane, enflurane, and innovar. 97 90

The high mortality rate associated with revascularization for stenosis of the left main coronary artery and impairment of the left ventricle (classes III and IV) has been significantly reduced by a twofold approach: combating hypotension during induction of anesthesia and preventing ischemia resulting from anoxic arrest, often needed to facilitate the insertion of the left coronary anastomoses. These two goals have been successfully achieved by (1) a readiness to institute circulatory assist by means of femoral-to-femoral cardiopulmonary bypass and (2) augmentation of coronary flow through immediate insertion of a vein graft between the aorta and right coronary artery, if the anatomy permits.
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PMID:Revascularization of the stenotic left main coronary artery and impaired left ventricle. 107 66

Twenty-four dogs were divided into five groups. Under pentothal sodium anesthesia, those in the control group received no further manipulation; another group underwent laparotomy only; and dogs in the last three groups had induced pancreatitis, intestinal ischemia and duodenal perforation, respectively. An analysis was made of serum and peritoneal lavage fluid in the dog of each group at 30 minute intervals for four and one-half hours. Parameters which were significantly elevated in dogs with pancreatitis compared with other groups included fluid amylase, lactate dehydrogenase, proteolytic activity and intestinal alkaline phosphatase and serum amylase. We judge that these biochemical differences in the lavage fluid, when taken with the physical characteristics of the fluid and the clinical symptoms, can significantly aid the clinician in arriving at the diagnosis of acute pancreatitis.
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PMID:Use of peritoneal lavage in the diagnosis of experimental acute pancreatitis. 112 80

Continuous electroencephalogram (EEG) monitoring was used during 213 carotid endarterectomies in 157 patients to identify cerebral ischemia. General anesthesia was used for all patients. An intraluminal shunt was not used routinely, but was inserted in 23 operations when EEG abnormalities associated with ischemia appeared. EEG changes occurred in 31 operations (14.5 percent). Four patterns of abnormal recordings were identified and are discussed. Six patients developed ischemic EEG changes in association with hypotension during endarterectomy. In two of these patients changes appeared with a blood pressure drop of only 20 mm. Hg below preoperative levels. Four patients with internal carotid artery back pressures of 75 to 100 mm. Hg developed EEG abnormalities which disappeared after shunt insertion. Our experience emphasizes the value of continuous EEG monitoring in detecting inadequate cerebral perfusion.
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PMID:An evaluation of electroencephalographic monitoring for carotid study. 118 21

The authors present a series of 64 patients with arterial embolism in healthy arteries. 53 of these patients underwent one or several embolectomies, using a Fogarty catheter. Although arterial embolism has a poor prognosis owing to the constitutional background (15 p. 100 mortality and 12 p. 100 amputations), this is mainly due to the age of the patient. The severity of the initial attack and the delay between embolism and embolectomy seem to be the main factors in prognosis. Massive ischemia causes severe symptoms in these fragile patients and an early cure is necessary to compensate this disturbance. Heparin perfusion, whilst awaiting surgical treatment, is essential. Embolectomy by Fogarty's catheter may be carried out under local anesthesia; this remains the essential measure and has greatly improved the prognosis of this disease which used to be fatal in almost 60 p. 100 of cases, even in healthy arteries.
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PMID:[Embolism in healthy arteries]. 119 87

Two patients developed unilateral central retinal artery and posterior ciliary artery occlusions related to ocular compression during general anesthesia. One patient had evidence of extensive choroidal ischemia with diffuse hypopigmentation, pigmentary mottling of the posterior pole, and disc edema. Electroretinography showed diminution of the A and B waves. The other patient showed patchy choroidal ischemia with subsequent development of wedge-shaped areas of pigmentary atrophy and mottling in the midperiphery. Iridocyclitis and prolonged hypotony were also present. Retinal and posterior ciliary artery occlusion (perhaps at the level of the ophthalmic artery) can occur as a result of ocular compression by a face mask or an improperly positioned headrest. Systemic hypotension is a factor in many cases. Proper positioning of the head on an adequate headrest and avoidance of ocular compression will prevent the occurrence of retinal and choroidal occlusion during general anesthesia.
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PMID:Ischemia of ciliary arterial circulation from ocular compression. 120 Aug 96


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