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

Spinal cord ischemia with resultant paraplegia or paraparesis remains an important clinical problem after operations on the thoracoabdominal aorta. Because hypothermia has a protective effect on ischemic neural tissue, we developed a baboon model of spinal cord ischemia to simulate the situation encountered clinically for resection of aneurysms of the thoracoabdominal aorta and to determine whether profound hypothermia produced by hypothermic cardiopulmonary bypass has a protective effect on spinal cord function. After cardiopulmonary bypass was established, the aorta was clamped distal to the left subclavian artery and proximal to the renal arteries for 60 minutes. Group I animals (n = 9) underwent aortic clamping at normothermia (37 degrees C), and group II animals (n = 9) were cooled to a rectal temperature of 15 degrees C before aortic clamping and underwent cardiopulmonary bypass at this temperature until the aorta was unclamped. Of the eight operative survivors in group I, six animals were paraplegic and two were paraparetic, whereas all six group II animals that survived the procedure were neurologically intact (p = 0.0002). The protective effect of hypothermia was associated with blunting of the hyperemic response of spinal cord blood flow (determined by the radioactive microsphere technique) in the lower thoracic and the lumbar segments of the spinal cord after unclamping of the aorta. Profound hypothermia produced by hypothermic cardiopulmonary bypass may be an effective method of protection of the spinal cord in patients undergoing repair of aneurysms of the thoracoabdominal aorta and may reduce the prevalence of ischemic injury to the spinal cord.
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PMID:Profound systemic hypothermia protects the spinal cord in a primate model of spinal cord ischemia. 824 34

We tested in pigs the hypothesis that regional deep hypothermia of the spinal cord achieved by cerebrospinal fluid cooling will protect against ischemic injury during thoracic aortic cross-clamping. Eight control animals underwent aortic cross-clamping at the distal aortic arch and just above the diaphragm for 30 minutes. Eight experimental animals had placement of two subarachnoid perfusion catheters through laminectomies at T4 and the lower lumbar region. The subarachnoid space was perfused with normal saline solution at 6 degrees C delivered by gravity infusion, with infusion rates adjusted to maintain cord temperatures at less than 20 degrees C. After 30 minutes of aortic cross-clamping, the infusion was stopped and the cord allowed to warm to body temperature. Hind limb neurologic function was graded by Tarlov's scale. All of the animals in the control group had complete hind limb paraplegia (Tarlov grade 0) postoperatively. Seven of the 8 animals in the experimental group had preservation of hind limb motor function (Tarlov grade 2), and 1 animal had complete hind limb paraplegia (Tarlov grade 0) (p = 0.002, Fisher's exact test). We conclude that regional deep hypothermia of the spinal cord in pigs does provide some protection from ischemic injury during thoracic aortic cross-clamping. Clinically this may be a useful adjunct for prevention of paraplegia during thoracic aortic operations.
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PMID:Regional deep hypothermia of the spinal cord protects against ischemic injury during thoracic aortic cross-clamping. 827 21

We have investigated the effects of mild whole body hypothermia on the amplitude and latency of somatosensory evoked potentials (SEPs) in control subjects (n = 12) and patients (n = 15) with chronic compressive or contusive spinal cord injury (SCI). Mild hypothermia (-1 degree C) was induced by controlled circulation of propylene glycol through a 'microclimate' head and vest garment while reductions in oral and limb temperatures were monitored. Cooling induced a delayed onset and reduced amplitude of tibial nerve SEPs in control subjects. All SCI patients with recordable SEPs (n = 11) showed similarly delayed onset of the cortical response. In contrast to the controls, nine of the 11 SCI patients showed an increase in amplitude of cortical SEPs. In three of these patients the increase in amplitude exceeded 100% of the precooling values. The cooling-induced changes in SEP amplitude and latency reversed on rewarming for both groups. The cooling-induced increases in cortical SEP amplitude support the a priori hypothesis that cooling would enhance central conduction in some SCI patients with conduction deficits due to focal demyelination.
Paraplegia 1993 Nov
PMID:Effects of induced hypothermia on somatosensory evoked potentials in patients with chronic spinal cord injury. 829 82

The protective effect of a modified epidural cooling technique was assessed in a rabbit spinal cord ischemia model. The epidural space around the lumbar segments with induced ischemia was continually perfused with cold (5 degrees C) isotonic saline via two communicating spinal canal openings. This procedure allowed the spinal cord to be kept deeply hypothermic (< 15 degrees C within central gray matter) during the ischemic period. The animals were subjected to either normothermic ischemia (Group A) or hypothermic ischemia (Group B). Each group contained three subgroups of animals undergoing 20, 40, or 60 minutes of aortic ligation. Their neurological outcomes were evaluated up to 48 hours postischemia, and the intergroup differences were compared. Two days postischemia, all of the animals were sacrificed by transcardial perfusion-fixation and their lumbar segments were processed for histopathological examination. In addition, in animals with 60-minute ischemia, spinal somatosensory evoked potentials were recorded during surgical intervention and again after 48 hours. In the normothermic animals, a high incidence of paraplegia was detected: in 40% after 20 minutes of ischemia, in 75% after 40 minutes, and in 100% after 60 minutes. In contrast, all of the hypothermic animals exhibited full neurological recovery even after 60 minutes of ischemia. Both electrophysiological and histological observations clearly correlated with the neurological findings. The results suggest that deep spinal cord hypothermia produced by epidural perfusion cooling provides effective protection against protracted spinal cord ischemia in rabbits.
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PMID:Epidural perfusion cooling protection against protracted spinal cord ischemia in rabbits. 841 Feb 53

Seven patients with complex thoracic aortic aneurysms were operated on using profound hypothermia and circulatory arrest through a left thoracotomy. Three patients had false aneurysms, 2 had large aneurysms precluding access for proximal control, 1 patient had had previous hemiarch replacement, and 1 patient had a thoracoabdominal aneurysm. All patients were cooled on partial cardiopulmonary bypass until the electroencephalogram was isoelectric (approximately 15 degrees C rectal temperature). Circulatory arrest times ranged from 7 to 56 minutes (median, 34 minutes). There was one death due to cardiac failure, and paraplegia developed in 1 patient. The 6 survivors are otherwise well at a median of 12 months postoperatively. Hypothermia and circulatory arrest is an invaluable technique for the treatment of complex aortic aneurysms requiring left thoracotomy for resection. The techniques employed are described and the indications for their use are discussed.
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PMID:Deep hypothermic arrest and left thoracotomy for repair of difficult thoracic aneurysms. 846 33

Paraplegia caused by irreversible lesions of the spinal cord is one of the major possible complications after scoliosis surgery. Several monitoring methods have been proposed but none are completely satisfactory. Since 1986 the authors assessed motor pathways during scoliosis surgery, using electrical stimulation of the motor cortex and lower limb muscle recordings (tibialis anterior muscle). Twenty-seven patients were included in this study: 25 with idiopathic scoliosis and 2 with dorsal kyphosis. Recordings in anesthetized patients with hypothermia were performed before and after spinal derotation during the surgical procedure. Magnetic cortical stimulation was carried out in ten awake patients before and after surgery. Reproducible responses were obtained in 22 patients under anesthesia. In eight patients no difference of the latency of the muscle response was detected before and after the correction of the spinal angulation. In 14 patients the increase of latency ranged from 0.4 ms to 5.2 ms. No correlation was found between the slowing of motor conduction and the magnitude of spine correction. No central neurologic complications were seen after surgery. The authors concluded that their study demonstrated that motor pathway assessment in anesthetized patients can be performed at different times during the surgical procedure. This technique should help in the future monitoring spinal function during scoliosis surgery.
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PMID:Monitoring of the motor pathway during spinal surgery. 848 44

Between April 1987 and March 1995, 198 patients (133 males [67.17%] and 65 female [32.83%]; mean age 63.85 years) underwent descending thoracic aortic aneurysm repair. Of these, 142 patients (71.71%) had symptoms. In most patients (n = 123 [62%]) the aneurysmal disease was extensive, involving at least two thirds of the descending aorta. In 153 patients (77.27%), the repair was completed with the simple clamp technique (mean clamping time 24.6 minutes). Left atrium-to-femoral bypass was used in 26 patients (13.13%) at high risk (mean clamping time 37.4 minutes). Profound hypothermia and circulatory arrest were necessary in 19 patients (9.6%) with extensive aneurysms that involved the arch and ascending aorta (mean circulatory arrest time 46 minutes). Operative mortality was 5.1% (n = 10). The causes of death were cardiac in three patients (1.5%), pulmonary in four (2.0%), and renal in three (1.5%). Postoperative paraplegia occurred in three patients (1.5%). Important predictors (p < 0.05) of mortality at regression analysis included renal failure, pulmonary complications, and paraplegia. The only independent predictor of paraplegia was clamping time. In conclusion, the simple clamp procedure remains the technique of choice in the majority of patients with descending aortic aneurysms. Atriofemoral bypass is an important adjunct in patients at high risk.
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PMID:Results of contemporary surgical treatment of descending thoracic aortic aneurysms: experience in 198 patients. 873 64

All patients undergoing resection of thoracic or thoracoabdominal aneurysms at Mount Sinai Hospital since November 1993 had spinal cord function monitored with somatosensory-evoked potentials as part of a multimodality approach to reducing spinal cord injury. In the segment to be resected, each pair of intersegmental vessels was sequentially clamped, and they were subsequently sacrificed only if no change in somatosensory evoked potentials occurred within 8 to 10 minutes after occlusion. Adjunctive protective measures included mild hypothermia (31 degrees to 33 degrees C), distal perfusion, corticosteroids, maintenance of high normal blood pressures, avoidance of nitroprusside, and cerebrospinal fluid drainage. Ninety-five consecutive patients operated on since 1993 (group II) were compared with 138 earlier patients (group I). Preoperative characteristics such as age, sex, etiology of aneurysm, emergency operation, and reoperation did not differ between groups, nor did operative variables such as incidence of rupture and extent of resection. Group I had slightly more smokers and slightly fewer hypertensive individuals. Group II patients had a significantly better outcome with respect to in-hospital mortality (10.5% vs 18%, p = 0.045) and paraplegia (2% vs 8%, p = 0.008). By multivariate analysis, rupture and diabetes were associated with significantly higher in-hospital mortality, and smoking greatly increased the incidence of paraplegia. The extent of the aneurysm was a major determinant of mortality and paraplegia. The low paraplegia rate in group II was achieved without reattachment of a single intercostal or lumbar artery. No patient with fewer than 10 intersegmental arteries severed had paraplegia, and spinal cord ischemia was reversible in three patients after adjunctive maneuvers were performed to improve perfusion, suggesting that spinal cord blood supply is unlikely to depend on a single "artery of Adamkiewicz."
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PMID:Looking for the artery of Adamkiewicz: a quest to minimize paraplegia after operations for aneurysms of the descending thoracic and thoracoabdominal aorta. 891 16

Aortic dissection is severe disease, but recently surgery of aortic dissection is reported in good results. In order to improve results, three adjunctive methods have been progressed recently; intraoperative color Doppler retrograde cerebral perfusion and deep hypothermia. Intraoperative color Doppler reveals dynamic hemodynamics and structural information in aortic dissection in real time which leads to proper surgical treatment to obtain maximum effects with minimum invasiveness. To carry out thrombus obliteration in false lumen by informations of intraoperative color Doppler leads to a healing in aortic dissection. Retrograde cerebral perfusion during surgery of aortic dissection permitted simple procedure and good surgical results with reduced neurological complications. Deep hypothermia for protection of spinal cord and other organs also yielded good operative results and reduced rate of paraplegia.
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PMID:[Recent progress in adjunctive methods during surgery of aortic dissection]. 896 92

The major cause of spinal cord injury, during and after aortic surgery, is based on the occurrence of one or more of the three following events: (1) the duration and degree of ischemia;(2) failure to re-establish blood flow to the spinal cord after the repair; and (3) a biochemically mediated reperfusion injury. Clinically, this manifests either as permanent or reversible paraplegia or paraparesis, or a neurogenic bladder. For more than 40 years, numerous methods have been attempted to prevent paralysis, and some of the newer technical innovations include reducing the duration of ischemia, the use of newer centrifugal pump distal perfusion techniques, localized hypothermia, intrathecal maneuvers, pharmacological agents, angiography, somatosensory-evoked potential monitoring, spinal motor-evoked potential monitoring, hydrogen mapping, not resecting the posterior aortic wall, the use of stents, and a spectrum of various pharmacological agents to prevent reperfusion injury to the spinal cord. Some of these techniques and agent seem to be effective at reducing the risk of spinal cord injury.
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PMID:New and future approaches for spinal cord protection. 926 40


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