Cardiogenic shock during rewarming following hypothermia in dogs

Cardiogenic shock during rewarming following hypothermia in dogs

ANNUAL MEETING Cleveland Metropolitan General Hospital, 3395 Scranton Road, Cleveland, Ohio 44109; CaseWestern Reserve University School of Medicine...

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Cleveland Metropolitan General Hospital, 3395 Scranton Road, Cleveland, Ohio 44109; CaseWestern Reserve University School of Medicine, Cleveland, Ohio 44106). Seven isolated monkey brains (White, R. J., Albin, M. S., Verdura, J., and Locke, G. E., J. Neurosurg. 27, 216, 1967), vascularly supported by heparinized donor monkeys through a femoralbilateral carotid arterial shunt, were instrumented for continuous cortical and depth electrography, intracerebral temperature, and carotid pressure. Each donor was similarly monitored. Discontinuous measurements of POT, Pco,, glucose, lactate, pyruvate, hematocrit, and pH were made across the brain. Cerebral blood flow (CBF) was determined by measuring cerebral venous return in a heated recording reservoir which was pump-returned to the donor. For cooling (and rewarming) a single core heat exchanger was interposed in the arterial line and the brain suspended in a reservoir filled with temperature-controlled fluid. During cooling, wit,h normalization of donor arterial pressure, PO,, PCO, and pH, cerebral blood flow fell on an average of 1 cc/l”C. At 13 f 2°C the CBF frequently remained constant or increased without further lowering of brain temperature unless arterial inflow was mechanically reduced. After 15 min of ischemia (average brain temperature 7.3 k 1°C) initial CBF averaged l&14 cc/100 g/min. Above 15°C rewarming curves for CBF and cerebral temperature retraced their cooling curves. These experiments demonstrated the ability of the isolated primate brain to autoregulate its CBF during cooling and rewarming with the possibility of loss of autoregulation at or near 13°C. 48. Survival of Extracorporeallu Cooled Dogs After One HOUT Circulatory Arrest. V. P. POPOVIC, I. KOSTOLNY,* K. PASS,* Z. KARCIOGLU,* AND PAVA POPOVIC* (Department of Physiology, Emory University Medical School, Atlanta, Georgia 30322). It has been shown that hibernators, which withstand a profound decrease in body temperature for weeks at a time, undergo a profound hemodilution during the hibernating period (Popovic, V., Amer. J. Physiol. 207, 1345, 1964). In order to simulate this condition in deep hypothermia, dogs were extracorporeally cooled to a body temperature of 46°C and then rewarmed after a l-hr circulatory arrest. Only glucose saline solution was used as the priming volume, leading to a profound hemodilution. However, this technique alone as well as several other singular techniques (such as drainage of the left heart by a catheter during the period of cold-induced failure and arrest in order to pre-

ABSTRACTS vent pulmonary congestion; rapid cooling and rewarming of the animals; hypervolemia of the blood induced during the last part of rewarming; lowering of the systemic arterial blood pressure just before or immediately after circulatory arrest; and a much decreased positive pressure respiration during profound cooling and rewarming) did not lead to a full and permanent recovery of the dogs after rewarming. Eighty to 90% of these animals died during or shortly after rewarming. The combination of two or three of these techniques was also ineffective. In the last group of experiments (10 animals), however, in which all these techniques were combined, every dog survived deep cooling and the extended circulatory arrest. In all cases the recovery was so rapid that 15 min after rewarming, the animals were already sitting up, and 13 hr later they were walking, eating, and drinking. No neurological or other ill effects were observed during the next 60 days. (Supported by grants from John A. Hartford Foundation, NIH, and NASA.) 49. Cardiogenic Shock During Rewarming Following Hypothermia in Dogs. WALTER ZINGG (Department of Surgery, University of Toronto and Research Institute, Hospital for Sick Children, Toronto, Ontario). A fall in body temperature due to exposure (accidental hypothermia) is a dangerous condition with a high mortality. Death may occur during or after the rewarming phase. The fatal outcome occurring after rescue while treatment is in progress is particularly disappointing; it is said to be due to “rewarming shock.” The pathogenesis of the rewarming shock is not clear. A series of anesthetized dogs were cooled (blood stream cooling) to 30°C and either warmed immediately or after a period of 6 hr at 30°C. Data on the hemodynamics and on the acid-base balance were collected throughout the experiments. Reliable data were obtained on 51 dogs as follows: Survivors of acute hypothermia Survivors of prolonged hypothermia Died during cooling Died during prolonged hypothermia Died during rewarming following acute hypothermia Died during rewarming following prolonged hypothermia

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A metabolic acidosis was found in the majority of the experimental animals, but a relationship between degrees of acidosis and mortality could not be demonstrated. A definite pattern of the hemodynamic changes was not found (pressure, flow,

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MEETING

resistance, in systemic and in pulmonary circulation). The calculated values of the work performed by ihe left and right ventricles always fell during cooling and rose during warming; a secondary fall preceded death during the warming phase. The animals surviving prolonged hypothermia had a significantly higher systemic arterial pressure before cooling than the other experimental animals. The findings suggest that rewarming shock is caused by a failure of the pumping mechanism of the hc~art. The hemodynamic manifestations are as variable as those observed in other cases of cardiogenie shock, for instance, after myocardial infarci,ion. (Supported by the Defence Research Board of Canada.) in Frog Muscle at 0°C. C. NEVILLE (Department of Physiology, University of Colorado Medical Center, Dc~nrer. Colorado 80220).

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Glycincl is accumulated against a concentration gradient by frog muscle at 0°C. At this temperature the metabolism of glycine and its incorporation inlo protein are insignificant in comparison to the rate of uptake. Although the rate of accumulation is reduced to about 4% of its rate at 25”C, after 4 or 5 days of incubation cellular levels are achieved which may be as high as 16 times the external cdoncf,ntration. The actual level achieved is affected by pretreatment of the muscles at 25°C. Muscles washed for 6 hr prior to incubation at 0°C accumulated significantly less glycine than freshly isolated muscles. Addition of glycine or insulin to the washing medium increases subsequent uptake; in both cases the higher level achieved is maint,ained for up to 13 days. When both glycine and insulin are added to the washing medium their effects arc additive. The time course of glycine efflux from previously loaded muscles was studied at 0°C. After an initial fast fraction which may rcprrsrnt loss from the extracellular space, efflux became an exponential process whose rate constant increased with increasing concentrations of glycine in the external medium. These results will be interpreted in terms of an active transport carrier model and an adsorption model. (Supported in part 1)~ Public Health Service Grant RR-05357.) 51.

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THOMAS ALGARD,* ASHWOOD-SMITH, AKD

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J. P. VANNETTEN,* B. D. HORNE* (De-

M. J. part,ment of Biological Sciences? University Vicloria, Victoria B.C.. Canada).

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receptor molecules present in the cytoplasm and perhaps the nuclei of target tissue cells (Taft. D., and Gorski, J., Proc. Nat. Acad. Sci. C. h’. A. 55, 1966; Nolides, A. C., Endocrinology 87, 987, 1970). Sucrose density gradient, centrifugation coupled with tritium-labeled estradiol reveals selective binding in the 9-10s region of the gradient. Despite reports that no significant alteration in reception follows freezing (Jungblut, P. WV.,el (cl., ivy “Wirkungsmechanismen der Hormone” (P. Karlson. Ed.), p. 74, 1967), we have recently ol~tainetl evidence that estrogen binding in the 9-10s region is substantially reduced after freezing with liquid nitrogen. Others have reported that freezing procedures were routinely employed at som(‘ stt’l) in their experiments (Korenman. S. G., and Rae. B. R., Yroc. Sal. Acad. Sci. U. S. A. 61, 1968). In this paper, evidence will be presented which suggests that freezing to -196°C followed by fast thawing causes a reduction in binding in the 9-10s region which approaches 50%. Such damage has been noticed following freezing of immature rat uterine and calf endometrial lysates. Rat, uterine lysate stored for 48 hr at -15°C after freezing to -196°C shows a complete loss of binding a(ati\;ity in the 9-10s region. Unlike an estradiol-sensitive transhydrogenase system from human placenta which is nearly completely protected from freeze/thaw-damage in the presence of &radio1 (unpublished), the 9-10s receptors are equally friable in the presence or absence of exogenous estrogen. It has been reported that in the presence of 0.3 M KC1 the 9-10s receptor reversibly dissociates into 4-5s components (Korenman. S. G.. and Rao, B. R., Proc. Nat. Accrd. Sci. Cr. S. A. 61, 1968). This work was done on pregnant rabbit uteri which had been frozen with solid CO?. Under this condition, a shift in S value of receptors was reported but no mention was made of an increase in total binding activity. Our preliminary studies made on fresh calf endometrium show a similar shift in S value of recepiors but furthermore revealed a significant increase in estradiol binding by ths KCl-dissociated component. Studies are now in progress to determine whether or not freezing and thawing, with or without exogenous estradiol, will result in an alteration in the apparent increase in total binding produced on fresh calf endomctrial lysate by 0.3 M KU. 52.

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Cells. C. E. HUGGINS AYD H. SUZUKI* (Department of Surgery, Harvard Medical School and the General Surgical Services, and Blood Bank and Transfusion Service, Massachusetts General Hospital, Boston. Massachusetts 02114).

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