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Query: UMLS:C0020672 (hypothermia)
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Most congenital heart anomalies now can be surgically corrected in a neonate or very young infant. Because their hearts are so small, it is advantageous to work in a bloodless and motionless operative field. Deep hypothermia with circulatory arrest provides this setting. Physiologic problems associated with hypothermia are minimized by inducing general vasodilatation with large doses of methylprednisolone. Surface cooling is done with ice blankets and small sandwich bags filled with crushed ice. The patient's temperature gradually falls to 75.2 F (24 C). After median sternotomy, core cooling can be used to bring the patient's temperature to the desired 68 F (20 C). Circulatory arrest is produced by draining blood into the reservoir and cross-clamping the great vessels and venae cavae. It can be maintained for up to 60 minutes. In infants over six months and over 6 kg (13.2 lb), moderate hypothermia 77 F (25 C) and low perfusion (1/4-1/3 of normal) with short periods (10 to 15 minutes) of circulatory arrest improve operative conditions and allow correction of the most complicated congenital heart defects.
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PMID:Technic of deep hypothermia and circulatory arrest in the neonate and infant. 127 20

Since our initial experience on April 28, 1989, a total of nine patients have received treatment for giant cerebral aneurysm using cardiopulmonary bypass with deep hypothermia and circulatory arrest. The following data summarize our findings associated with these patients. The average patient's age was 46 years (range: 16 to 59 years of age). Seven patients were female, two were male. The procedure required approximately eight hours to complete with an average cardiopulmonary bypass time of 104 minutes (range: 60 to 140 minutes). Circulatory arrest time averaged 26 minutes (range, 12 to 45 minutes) with an average of 30 minutes (range: 10 to 62 minutes) required to cool the patient to below 18 degrees C (64 degrees F). An average of 54 minutes (range: 28 to 81 minutes) was required to warm the patient to a bladder temperature of 36 degrees C (96.8 degrees F). During the cooling period, five patients went into asystole spontaneously, four patients required bolus of 20 mEq of potassium chloride, and upon rewarming, spontaneous defibrillation occurred in six patients. Three patients were defibrillated without difficulty with external shock. The average number of blood products administered in each of the nine patients was 3.6 units of packed red blood cells, 3 units of fresh frozen plasma, and 6.5 units of platelets. Six patients recovered postoperatively without complication, and the recovery of three patients was affected by the complex anatomical location of the giant aneurysm. Cardiopulmonary bypass with deep hypothermia and circulatory arrest offers an alternative approach to the treatment of giant cerebral aneurysms considered inoperable by conventional techniques. The effectiveness of each procedure depends on the collaborative efforts of every member of the perioperative nursing team, the neurosurgical team, the cardiac surgical team, the neuroanesthesiology team, and the perfusionists. Careful planning and anticipation at every stage of the surgery can reduce surgical time, cardiopulmonary bypass time, and most importantly, circulatory arrest time.
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PMID:Giant cerebral aneurysm repair. Incorporating cardiopulmonary bypass and neurosurgery. 192 49

Six female and 4 male patients (age, 23 to 75 years) underwent operation for difficult intracranial lesions. Preoperative diagnoses included four giant intracranial aneurysms, three base of skull glomus jugulare tumors, two arteriovenous malformations, and one cerebellar hemangioblastoma. All lesions were inoperable or nearly so by standard neurosurgical techniques. All patients were placed on total bypass via groin cannulations. Bypass times ranged from 111 to 269 minutes (mean, 174 minutes) with cooling times of 26 to 83 minutes (mean, 48 minutes) and warming times of 68 to 110 minutes (mean, 83 minutes). Circulatory arrest times ranged from 1.25 to 60 minutes with 1 patient not requiring arrest. The lowest core temperatures recorded varied from 8.4 degrees to 13.7 degrees C. There was one postoperative death and one major complication, both in patients with arteriovenous malformations. Eight patients (80%) have achieved an excellent result. Profound hypothermia with the option of circulatory arrest and exsanguination has been an indispensable adjunct to the safe management of intracranial aneurysm, glomus jugulare tumor, and hemangioblastoma.
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PMID:Cardiopulmonary bypass, profound hypothermia, and circulatory arrest for neurosurgery. 151 May 42

To evaluate the effects of 5% carbon dioxide (CO2) administration for hypothermic circulatory arrest, neurological evaluation and pathological studies were carried out on the canine brain. Twenty-two dogs were assigned to five groups: Group 1: Three dogs without hypothermia were sacrificed as the control group. Group 2: Nine dogs were subjected to surface hypothermia (20 degrees C) under deep ether anesthesia with 100% oxygen (O2) and hyperventilation. Circulatory arrest time was 30 min in Group 2A and 60 min in Group 2B. Group 3: Ten dogs were surface cooled (20 degrees C) under deep ether anesthesia with a 95% O2 and 5% CO2 mixture. Thirty minutes of circulatory arrest was instituted in Group 3A and 60 min in Group 3B. Dogs in Groups 2 and 3 were surface rewarmed and kept alive until they were sacrificed electively 6 or more months later. Results were as follows: (i) Postoperative neurological disturbance was detected in only two dogs in Group 2B. (ii) The percentage of damaged nerve cells among the total nerve cells counted in the cerebral cortex of the frontal lobe was significantly greater in Groups 2A (22.4%), 2B (30.1%), 3A (19.6%), and 3B (22.2%) compared with Group 1 (7.1%). (iii) The number of glia cells per nerve cell in the cerebellar dentate nucleus was significantly higher in Group 2B (27.2) than in Groups 1 (11.8), 2A (16.7), 3A (17.9), and 3B (18.6). (iv) The number of Purkinje cells in a 10-mm length of the cerebellum was markedly reduced to 89 in Group 2B compared with 122, 134, and 117 in Groups 1, 2A, and 3A, respectively. In conclusion, the results of quantitative pathological brain analysis reflected the incidence of postoperative neurological disturbance and suggested that the administration of 5% CO2 could prolong the time limit for circulatory arrest.
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PMID:The effects of 5% carbon dioxide on the quantitative analysis of long-term pathology of the brain after surface hypothermia. 210 59

Profound hypothermia protects cerebral function during circulatory arrest in the surgical treatment of a variety of cardiac and aortic abnormalities. Despite its importance, techniques to determine the appropriate level of hypothermia vary; studies of temperatures recorded from multiple peripheral body sites show inconsistent findings. The purpose of this study is to establish objective criteria to consistently identify intraoperatively the safe level of hypothermia. Our studies are based on experimental evidence showing a correlation between brain temperature and development of electrocerebral silence (ECS) on the electroencephalogram (EEG), and the recognition that the EEG, as an objective measure of brain function, can easily be recorded intraoperatively. We studied 56 patients who required circulatory arrest during operation for replacement of the ascending aorta or aortic arch (N = 55) or aortic valve replacement (N = 1). Peripheral body temperatures from the nasopharynx, esophagus, and rectum and the EEG were continuously recorded during body cooling. Circulatory arrest time ranged from 14 to 109 minutes. No peripheral body temperature from a single site or from a combination of sites consistently predicted ECS. There was a wide variation in temperature among body sites when ECS occurred: nasopharyngeal, 10.1 degrees to 24.1 degrees C; esophageal, 7.2 degrees to 23.1 degrees C; rectal, 12.8 degrees to 28.6 degrees C. Fifty-one (91%) of the 56 patients survived. Three had neurological deficits, none clearly related to hypothermia. Two patients (3.6%) required reexploration for postoperative bleeding. We conclude that monitoring the EEG to identify ECS is a safe, consistent, and objective method of determining the appropriate level of hypothermia.
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PMID:Determination of brain temperatures for safe circulatory arrest during cardiovascular operation. 337 76

Aortic arch resection remains a challenging problem. At present, the most reliable technique appears to be profound hypothermia and circulatory arrest, although long cardiopulmonary bypass times and coagulopathy remain significant problems. Interest in alternative procedures continues. Herein, we report our experience of aortic arch replacement in eight patients using profound hypothermia (12 to 17 degrees C) and circulatory arrest in six patients (Group I) and moderate (20 degrees C) hypothermia with low flow (200 ml/min), pressure-monitored (100 mm Hg) innominate artery perfusion by way of a 14 Ga. cannula in 2 (Group II). Arch repair was by patch graft in two, and tube graft in six. Concomitant ascending aortic replacement was performed in five, aortic valve replacement in four, and coronary bypass in two. Circulatory arrest times ranged from 15 to 71 minutes in Group I and were 15 minutes and 35 minutes in Group II. All patients survived. One patient in Group I had a neurologic injury of moderate severity, probably due to a hypoxic postoperative cardiac arrest. We have found low flow pressure-monitored innominate artery perfusion and moderate hypothermia to be simple and expedient, and we will continue use of this technique.
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PMID:Techniques of aortic arch replacement: profound hypothermia versus moderate hypothermia with innominate artery perfusion. 355 44

Circulatory arrest during profound hypothermia is a safe technique of cardiac surgery when used in selected instances. Despite its proven safety, the degree of cerebral protection offered by this technique is still poorly defined. Ten dogs anesthetized with Pentothal (thiopental sodium) were surface cooled to 32 degrees C. They were placed on cardiopulmonary bypass, cooled to 13 degrees C (cerebral temperature), and then underwent one hour of circulatory arrest. At the end of the arrest period, the dogs were rewarmed, resuscitated, and successfully weaned from bypass. A control group of 6 dogs were subjected to the same protocol but without the one-hour period of circulatory arrest. There were no group differences in animal weight, duration of surface cooling, cardiopulmonary bypass, or rewarming, mean flow, or mean arterial pressure. After a 7-day observation period, the dogs were killed with rapid tissue fixation using formalin. No neurological deficits were noted in any of the dogs during the observation period. The fixed brains were examined by a neuropathologist. No gross or microscopic evidence of cerebral hypoxia was seen in any of the animals. We conclude that one hour of circulatory arrest under profoundly hypothermic temperatures produces no detectable neurological changes or histological evidence of cerebral hypoxia.
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PMID:The protective effect of profound hypothermia on the canine central nervous system during one hour of circulatory arrest. 395 95

Circulatory arrest to the lumbar spinal cord of adult cat was produced by occlusion of the descending aorta and concurrent arterial hypotension. Local hypothermia of the cord was induced by paraffin oil at 5 C, which was circulated over the exposed surface of the cord, using the laminectomy wound as a trough. Intramedullary temperature was 15 C at a depth of 5 mm. In 10 control animals oil at 37 or 5 C was circulated over the exposed cords (normal-normothermic and normal-hypothermic controls with 1 and 2 hours hypothermia). Three animals had circulatory arrest and recirculation in normothermia (ischemic-normothermic) and 3 in hypothermia (ischemic-simultaneous hypothermia). Three had circulatory arrest and 15 minutes of recirculation in normothermia followed by 1 hour of hypothermia (ischemic-delayed hypothermia). The medial and lateral portions of the anterior gray horns of the last lumbar spinal segment were studied in the light and electron microscopes. Ischemic-normothermic tissue showed 20% shrinkage in mean areas of neuronal perikarya and massive "watery" swelling of astrocytic cell bodies and processes. Within neuronal perikarya and dendrites, cytoplasm increased in electron density, ribosomes dispersed, Golgi apparatus swelled and mitochondria swelled with loss of matrix density and disruption of cristae. Axons and axon terminals did not increase in size, but mitochondria within these structures doubled in size without loss of matrix density or change in pattern of cristae. Synaptic vesicles were no longer uniform in size, and they were clumped away from the synaptic cleft and diminished in number. Lysosomes were unchanged in appearance and size. Mitochondria of astrocytes underwent approximately fourfold enlargement without loss of matrix density or pattern of cristae. Bundles of astrocytic microfilaments were fragmented, spread apart and diminished in quantity. Oligodendroglia and endothelial cells were unchanged. Normal-hypothermic animals were similar to normal-normothermic except for clefts in rough endoplasmic reticulum of neurons and dendrites. These clefts were formed by a separation of the cisternal membrane from the adjacent row of ribosomal rosettes. Ischemic-simultaneous hypothermia animals had findings identical to normal-hypothermic animals. Ischemic-delayed hypothermia animals were similar to ischemic-normothermic animals except for less swelling of astrocytic processes, greater swelling of astrocytic mitochondria and less alteration of microfilaments. The findings show that ischemia in normothermia brings about alterations in virtually every organelle of the neurronal perikaryon except the lysosome. Simultaneous hypothermia in ischemia prevents the protean alterations of ischemia, whereas hypothermia delayed until after the ischemic episode only slightly modifies the cellular lesions found in ischemic-normothermic animals.
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PMID:Electron microscopy of cat spinal cord subject to circulatory arrest and deep local hypothermia (15 C). 472 89

Between November 1975 and June 1977, 49 children underwent repair of complicated cardiac defects with the aid of deep hypothermia. Circulatory arrest was used in 28 cases. Nine children died (18%) due to early postoperative heart failure. A decisive cause of death in terms of important cardiovascular defects, which were either unknown or not correctable at the time of repair, was found in 6 patients. Children with complicated forms of congenital heart disease requiring an extensive repair were overrepresented among those who died. Hence, there was an excess in the duration of bypass among nonsurvivors (p less than 0.01) whereas the patient's age at operation, the use of circulatory arrest and the duration of aortic occlusion had no bearing on operative mortality. Cerebral blood flow (CBF) and cerebral metabolism were studied in 9 survivors. A negative correlation (r = -0.67) was found between the duration of circulatory arrest and CBF measured directly after surgery. CBF was reduced to values below 0.2 ml . g-1 . min-1 in 3 children with long periods of circulatory arrest. The cerebral uptake of oxygen and glucose was normal both before and after surgery. Two separate interviews with the parents were performed, the first one 3-22 months and the second one about 3 years after surgery. No serious neurological symptoms or psychomotor disturbances were reported. However, in 3 children operated with circulatory arrest, difficulties in performing more delicate motor activities were noted by the parents. The findings indicate that circulatory arrest should be used with caution and total arrest periods exceeding 60 min avoided.
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PMID:Cerebral blood flow and cerebral metabolism in children following cardiac surgery with deep hypothermia and circulatory arrest. Clinical course and follow-up of psychomotor development. 682 May 74

Although cardiopulmonary bypass (CPB) with hypothermia and circulatory arrest is routinely used for certain cardiovascular procedures, its advantages have infrequently been applied for other unusual surgical problems. Fourteen patients (six men and eight women, average age 48 years, range 29 to 74 years) underwent 15 operations over a 4-year period beginning in November 1978. Preoperative diagnosis included giant middle cerebral aneurysm (n = 8), internal carotid aneurysm (3), basilar artery aneurysm (2), and medullary hemangioblastoma (2). All patients had lesions that were considered inoperable by standard neurosurgical techniques. Operative technique consisted of peripheral cannulation with a long and short femoral vein cannula for venous return (24 to 28F) and a single femoral arterial cannula (18 to 24F). CPB flows ranged from 1 to 3.5 L/min, and the total CBP times averaged 146 minutes (range 66 to 282 minutes). Circulatory arrest times averaged 21 minutes (range 5 to 51 minutes), with two patients having no period of circulatory arrest. Lowest core temperature ranged from 16 degrees to 20 degrees C, with cooling and rewarming aided by Brown-Harrison heat exchangers placed in a countercurrent fashion within the venous return line. The heart spontaneously defibrillated in six patients, and external countershock was required in nine patients. No difficulty was encountered with cardiac distention. The intended operation was accomplished in all cases with 13 of 14 patients being discharged from hospital, having had a good neurosurgical result. One patient sustained a hemorrhagic infarction of the cerebellum and pons and is presently recovering. Our experience indicates that peripheral CPB with induced hypothermia and circulatory arrest is a safe technique for approaching otherwise inoperable neurosurgical lesions.
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PMID:Reappraisal of cardiopulmonary bypass with deep hypothermia and circulatory arrest for complex neurosurgical operations. 687 41


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