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Query: UMLS:C0020672 (hypothermia)
 17,327 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effect of cooling and subsequent rewarming on the tissue respiration of canine hearts was studied during polycomponent ether-oxygen anaesthesia. The tests included the determinations of the activity of the dehydrogenases of the cytrate cycle, the content and activity of chromoproteids, the respiration rate of the mitochondrias on succinate, glutamate and ketoglutarate, the content of glycogen, the activity of the phosphorylases, hexokinase, lactate dehydrogenase, the content of lactate, pyruvate, adenyl nucleotides and creatine phosphate. Significant changes were noted in the content and activity of the above substances, acceleration of mitochondrial respiration, reduced energy regulation of respiration, and decreased amount of the adenyl components. It is suggested that under artificial hypothermia the processes of chromoproteids biosynthesis are enhanced, which results in an increased power of terminal respiration, and conformational rearaangements of the enzymes connected with the membranes occur.
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PMID:[Characteristics of energy metabolism in the myocardium under artificial hypothermia]. 19 79

Twenty experiments were conducted on dogs. The effect of hypothermia of different degree (from 18 to 20 degrees C and from 4 to 6 degrees C) on the carbohydrate metabolism and the extent of solubilization of hepatic enzymes (lactate dehydrogenase, glutamate dehydrogenase, urokaninase, DNA-ase, glucose-6-phosphatase) in prefusion-free preservation of the liver was studied. The preservation efficacy was assessed during the subsequent two-hour normothermic perfusion. A marked solubilization of the enzymes under study followed preservation of the liver at 18--20 degrees C; this indicated the loss of intactness of the cell membranes during the preservation. A moderate expenditure of the glycogen stores in the liver, and of sugar in the perfusate followed preservation of the liver at a temperature of 4--6 degrees C; this suggested an even suppression of hepatic metabolism and the prevalence of normal tissue respiration over glycolysis in the restoration of circulation in the liver.
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PMID:[Effect of hypothermia on metabolism in the liver during its preservation]. 68 13

It has been proposed that a single preoperative dose of a corticosteroid may protect the myocardium from ischemic injury during open heart surgery. To test this hypothesis, a prospective, randomized, double blind study was carried out in ninety-five patients undergoing coronary bypass surgery using intermittent ischemic arrest with systemic and local hypothermia. Half the patients received 2 gm (approximately 30 mg/kg) of methylprednisolone 2 hours prior to the initiation of cardiopulmonary bypass and the other half received a placebo. Postoperative electrocardiograms and blood levels of serum creatine phosphokinase (CPK), lactic dehydrogenase (LDH), and serum glutamic oxalacetic transaminase (SGOT) were compared in the two groups. No apparent difference was noted in the number of patients with significantly elevated levels of CPK, LDH, or SGOT or in the number with positive isoenzyme patterns of CPK and LDH. Moreover, there was no significant difference in the mean values of CPK, LDH, or SGOT between the two groups. The number of patients with electrocardiographic evidence of myocardial injury (10 per cent) was the same in both groups and no difference was noted in (1) the ease with which patients could be weaned from cardiopulmonary bypass, (2) postoperative arrhythmias, (3) postoperative bleeding, (4) postoperative respiratory insufficiency, and (5) length of hospital stay. It is concluded that a single preoperative dose of 2 gm of methylprednisolone offers no demonstrable protection to the myocardium from the effects of ischemia during coronary artery bypass surgery.
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PMID:Effect of methylprednisolone on myocardial preservation during coronary artery surgery. 77 98

The measurement of lactate dehydrogenase (LDH) release into perfusates after hypothermic storage was found to be a reliable index of ischemic injury of rabbit kidneys. Kidneys were exposed to warm and cold ischemia for varying periods. Each kidney was perfused before and after storage at simple hypothermia with 25 ml of a modified Collins solution. The venous effuent was collected in 5 ml fractions. Total LDH activity was measured in the first fraction after storage and used as a measure of ischemic tissue damage. It was confirmed that increasing the period of cold ischemia result in significant increases in LDH activity. The release of LDH into perfusates was then used to compare kidney damage after preservation with various fluids. With this method, it was not possible to demonstrate any difference in the extent of tissue damage after preservation with sodium-rich vs. potassium-rich perfusion fluid. Addition of steroids, vitamins and essential amino acids did not prevent or reduce tissue damage, estimated in this way. The effects of adding cryoprotectants to the perfusion fluid varied; LDH release following addition of 5% DMSO was significantly greater, and after addition of 5% glycerol smaller than the release after perfusion with a modified Collins solution alone. Stepwise addition of DMSO up to 20% resulted in serious tissue damage with a large LDH release into the perfusate.
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PMID:LDH release into perfusates of preserved kidneys. 78 32

Two cases with acute renal failure after prolonged hypothermia are presented. Both patients were found in come, became rapidly uremic and required hemodilaysis treatment. Although the laboratory findings were typical of severe muscle damage, e.g. elevated levels of serum creatinine phosphokinase, serum lactic dehydrogenase and serum aldolase activities, visible "crush-injuries" were not found. Acute renal failure was characterized by extreme catabolism and severe metabolic acidosis. After 4 and 10 hemodialyses respectively, the patients became polyuric and finally were discharges with normal renal and muscle function. Hypotension with diminished renal perfusion and nontraumatic rhabdomyolysis due to prolonged hypothermia are regarded as the dominant pathogenetic factors in the acute renal failure.
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PMID:[Acute kidney failure in hypothermia]. 89 29

Two different operative techniques for aorta-coronary bypass grafting were utilized in two comparable groups of patients. In one group (155 patients) distal anastomoses were carried out with the aorta cross-clamped and myocardial protection provided by profound local hypothermia (clamped group). In a second group (149 patients) distal anastomoses were carried out with the aorta unclamped and the left ventricle fibrillating and vented (unclamped group). Mortality rates were similar in the two groups (0.6 per cent in clamped group versus 1.3 per cent in unclamped group). The incidence of perioperative infarction was 15 per cent in the unclamped group and 8 per cent in the clamped group (p less than 0.05). Postoperative serum glutamic oxaloacetic transaminase (SGOT) and lactic dehydrogenase (LDH) levels were significantly higher for the first 4 postoperative days in the unclamped group than in the clamped group. Hemodynamic studies in a subset of each group revealed no important differences in left ventricular function in the immediate postoperative period. The data demonstrate that in patients undergoing aorta coronary bypass grafting, performance of distal anastomoses with aortic cross-clamping and profound local hypothermia results in less intraoperative myocardial injury than performance of distal anastomoses in the perfused, fibrillating, and vented left ventricle.
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PMID:The superiority of aortic cross-clamping with profound local hypothermia for myocardial protection during aorta-coronary bypass grafting. 108 Nov 70

Myocardial cell vulnerability to phospholipase C (PC-PLC) attack was investigated in three different preparations of rat myocardial cells: triacylglycerol (TG)-loaded, hypothermic/rewarmed and energy depleted myocytes. The attack by PC-PLC was evaluated as PC-PLC induced glycerol output due to the combined action of phospholipase C and intracellular lipases. PC-PLC induced glycerol output was significantly higher (p < 0.05) in all three myocyte preparations, compared to their respective controls. Cell morphology (% rod shaped myocytes) of TG-loaded or hypothermic/rewarmed myocytes was not different from their controls, whereas energy depleted myocytes almost exclusively were rounded up, due to hypercontraction of the myofilaments. Hypothermic/rewarmed and energy depleted myocytes showed a significantly higher release of lactate dehydrogenase (LDH), compared to their controls although the difference was much more pronounced in the latter. Finally, the cellular contents of ATP were maintained both in TG-loaded and hypothermic rewarmed myocytes, while energy depleted myocytes contained only about 25% of the normal ATP level. These results demonstrate that attack from exogenously added phospholipases can occur, not only in seriously damaged cardiac myocytes, but in myocytes with a more subtle damage as well.
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PMID:Myocardial cell vulnerability to exogenous phospholipase attack. 148 Jan 54

Inadvertent hypothermia due to massive infusion of stored blood can be prevented by pretransfusion warming. One approach is the heating of individual packs by means of electromagnetic conduction, which is a method safely used over the last 25 years. The prototype instrument, which has now been re-engineered, can effectively raise the temperature of a unit of blood to approximately 33 degrees C in less than 3 minutes. Using this new model, we found, in vitro, a modest increase in free plasma haemoglobin, but this was not accompanied by any change in potassium or lactic dehydrogenase levels and the mean red cell fragility was unaltered. In vivo, the survival of autologous red cells that had been stored for 33 days and then infused as a concentrate, having a mean haematocrit of 0.60, was measured at 24 hours and 21 days. Each donor acted as his own control. In paired studies, pretransfusion radiofrequency heating was shown to have no deleterious effect when compared to measurements using the unwarmed blood pack. It is concluded that this method can be recommended as safe.
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PMID:Method for the safe and rapid pretransfusion warming of stored blood: an in vitro and in vivo evaluation of a radiofrequency (RF) instrument. 159 50

The combined action of phosphatidylcholine preferring phospholipase C (PC-PLC) and intracellular lipases has recently been shown to cause glycerol output in energy deprived rat cardiomyocytes. In the present study we examined the effect of hypothermia and rewarming on PC-PLC evoked glycerol output in freshly isolated, calcium-tolerant myocytes. The cells were preincubated for 60 min at hypothermic (5 degrees C) or normothermic (37 degrees C) conditions in Krebs-Henseleit bicarbonate buffer (pH 7.4) supplemented with 1 mM DL-carnitine, 1% B.S.A. and 5 mM glucose. Addition of PC-PLC resulted in a significantly higher (P less than 0.05) output of glycerol in myocytes undergoing rewarming than in myocytes kept constantly at 5 degrees C or 37 degrees C. The values obtained for PC-PLC induced glycerol output (difference in glycerol output between incubations with and without PC-PLC) were 6.77 +/- 2.6 (37 degrees C), 4.54 +/- 1.7 (5 degrees C) and 22.85 +/- 5.9 (5-37 degrees C) nmol/10(6) cells.h. Rewarming in addition caused a significantly higher (P less than 0.05) leakage of lactate dehydrogenase (LDH) from the rewarmed cells as compared to cells at constant temperatures (5 degrees C or 37 degrees C). However, there was no additional effect of PC-PLC on LDH leakage. The elevated PC-PLC induced glycerol output in rewarmed myocytes was not related to a fall in the percentage of rod-shaped cells or a reduced cellular content of ATP, since no differences could be detected between the various myocyte preparations with respect to these parameters.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Effects of hypothermia and rewarming on phospholipase C-evoked glycerol output in rat myocardial cells. 163 71

The treatment of hypothermia associated with hemorrhage, exposure, or intraoperative intervention continues to represent a challenge for trauma care teams. An innovative technique for combining microwave heating with continuous temperature monitoring into a feedback-controlled system for blood warming has been developed. The effect of microwave warming on the structure and function of blood was compared with that in nonheated controls. Erythrocyte structural integrity (hemolysis) was evaluated by comparing levels of lactate dehydrogenase (LDH), potassium (K+), and plasma hemoglobin (PHGB), and hematocrit (HCT) in heated and nonheated (control) samples of banked red blood cells. Hemoglobin function was evaluated in fresh blood by comparing the P50 and hemoglobin electrophoresis of experimental and control samples. Prewarming temperatures were 3 degrees or 23 degrees C; temperatures after warming were 35 degrees, 37 degrees, or 39 degrees C. The results reflect the percentage of changes for 84 heated and 24 unheated blood samples. There were no statistical differences in any of the biochemical variables measured. The P50 for three heated and three unheated samples was 30.7 +/- 1.2 and 30.5 +/- 0.9 mm Hg (p greater than 0.05). There were no changes in the hemoglobin electrophoretic patterns in experimental or control samples. This system is designed to deliver microwave energy in a uniform and controlled manner, overcoming the limitations of conventional microwave ovens that in the past caused local overheating and subsequent hemolysis when used for blood warming. The structural and functional integrity of erythrocytes after microwave warming indicate the safety and effectiveness of this technique.
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PMID:The effect of in-line microwave energy on blood: a potential modality for blood warming. 163 11


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