Reversible reduction in dendritic spines in CA1 of rat and ground squirrel subjected to hypothermia-normothermia in vivo: A three-dimensional electron microscope study

A study was made at electron microscope level of changes in the three-dimensional (3-D) morphology of dendritic spines and postsynaptic densities (PSDs) in CA1 of the hippocampus in ground squirrels, taken either at low temperature during hibernation (brain temperature 2-4 degrees C), or after warming and recovery to the normothermic state (34 degrees C). In addition, the morphology of PSDs and spines was measured in a non-hibernating mammal, rat, subjected to cooling at 2 degrees C at which time core rectal temperature was 15 degrees C, and then after warming to normothermic conditions. Significant differences were found in the proportion of thin and stubby spines, and shaft synapses in CA1 for rats and ground squirrels for normothermia compared with cooling or hibernation. Hypothermia induced a decrease in the proportion of thin spines, and an increase in stubby and shaft spines, but no change in the proportion of mushroom spines. The changes in redistribution of these three categories of spines in ground squirrel are more prominent than in rat. There were no significant differences in synapse density determined for ground squirrels or rats at normal compared with low temperature. Measurement of spine and PSD volume (for mushroom and thin spines) also showed no significant differences between the two functional states in either rats or ground squirrels, nor were there any differences in distances between neighboring synapses. Spinules on dendritic shafts were notable qualitatively during hibernation, but absent in normothermia. These data show that hypothermia results in morphological changes which are essentially similar in both a hibernating and a non-hibernating animal.     

Hypothermic circulatory arrest for aortic dissection with cryoglobulinemia

Cryoglobulinemia is a cold-reactive autoimmune disease. A 64-year-old man with active cryoglobulinemia presented Stanford type A acute aortic dissection. He had been treated with immunosuppressive drugs and plasma exchange (PE) at our hospital; subsequently, qualitative analysis of cryoglobulin (CG) was negative. He underwent emergency ascending aorta replacement using cardiopulmonary bypass (CPB) under deep hypothermia circulatory arrest with selective cerebral perfusion. The total CPB time, aortic cross-clamp time, and selective cerebral perfusion time were 255, 153, 56 minutes, respectively, and the minimal nasopharyngeal temperature was 17.3°C. Our patient had no significant perioperative complications. Hence, if PE is performed appropriately and CG is negative, patients with cryoglobulinemia who exhibit severe preoperative symptoms can safely undergo surgery with deep hypothermia.     

Application of therapeutic hypothermia in the intensive care unit

Induced hypothermia can be used to protect the brain from post-ischemic and traumatic neurological injury. Potential clinical applications and the available evidence are discussed in a separate paper. This review focuses on the practical aspects of cooling and physiological changes induced by hypothermia, as well as the potential side effects that may develop. These side effects can be serious and, if not properly dealt with, may negate some or all of hypothermias potential benefits. However, many of these side effects can be prevented or modified by high-quality intensive care treatment, which should include careful monitoring of fluid balance, tight control of metabolic aspects such as glucose and electrolyte levels, prevention of infectious complications and various other interventions. The speed and duration of cooling and rate of re-warming are key factors in determining whether hypothermia will be effective; however, the risk of side effects also increases with longer duration. Realizing hypothermias full therapeutic potential will therefore require meticulous attention to the prevention and/or early treatment of side effects, as well as a basic knowledge and understanding of the underlying physiological and pathophysiological mechanisms. These and other, related issues are dealt with in this review.     

Therapeutic Hypothermia for Patients with Out-of-Hospital Cardiac Arrest in North Carolina

Introduction: While therapeutic hypothermia has been the standard of care for patients who suffer out-of-hospital cardiac arrest (OHCA), recent trials have led to an advisory statement recommending a focus on targeted in-hospital temperature management and against initiation of prehospital hypothermia with rapid infusion of cooled saline. The aim of this study is to review the experience with therapeutic hypothermia in North Carolina. Methods: We studied patients who suffered OHCA in North Carolina in 2012 captured in the CARES database as part of the Heart Rescue Project. We excluded patients without return of spontaneous circulation and patients without an advanced airway placed in the field to reduce selection bias. Bivariate distributions and multivariate logistic regression models were used to examine differences in survival to discharge and positive neurological outcome. Results: 847 patients were included in the analysis of pre-hospital hypothermia. Of these patients, 55% received prehospital hypothermia. Prehospital initiation of hypothermia was associated with higher survival to hospital discharge (OR 1.55, 95% CI 1.03–2.32) and improved neurologic outcome at discharge (OR 1.56 95% CI 1.01–2.40). In patients who survived to hospital admission (n = 537), in-hospital hypothermia was associated with a non-significant trend toward better survival to discharge (p = 0.18). Conclusion: We found that patients who received prehospital hypothermia had improved outcomes, a finding that may be due to a greater likelihood of receiving in-hospital hypothermia or a reflection of higher quality of pre-hospital care. These findings support ongoing efforts to improve all aspects of the chain of survival after cardiac arrest.     

A quality improvement project incorporating preoperative warming to prevent perioperative hypothermia in major burns

Background

Patients with extensive burn injuries are susceptible to a host of accompanying adverse effects should they develop perioperative hypothermia, which occurs in up to ¼ of all major burn cases. This quality improvement project aimed to reduce the incidence of perioperative hypothermia to below 10% of cases in patients with major burn (Total Body Surface Area [TBSA]?>15%), within a one year period.

Guía de práctica clínica de hipotermia perioperatoria no intencionada

The importance of the safety of our patients in the surgical theatre, has driven many projects. The majority of them aimed at better control and clinical performance; mainly of the variables that intervene or modulate the results of surgical procedures, and have a direct relationship with them.The Spanish Society of Anesthesiology, Critical Care and Therapeutic Pain (SEDAR), maintains a constant concern for a variable that clearly determines the outcomes of our clinical processes, “unintentional hypothermia” that develops in all patients undergoing an anesthetic or surgical procedure.SEDAR has promoted, in collaboration with other scientific Societies and patient Associations, the elaboration of this clinical practice guideline, which aims to answer clinical questions not yet resolved and for which, up to now, there are no documents based in the best scientific evidence available.With GRADE methodology and technical assistance from the Ibero-American Cochrane Collaboration office, this clinical practice guideline presents three recommendations (weak in favor) for active heating methods for the prevention of hypothermia (skin, fluid or gas); three for the prioritization of strategies for the prevention of hypothermia (too weak in favor and one strongly in favor); two of preheating strategies prior to anesthetic induction (both weak in favor); and two for research.     

亚低温对大鼠脑缺血炎症反应及P-选择素的影响

目的:观察亚低温对脑缺血再灌注后炎症反应及P-选择素表达的影响。方法:建立大鼠常温(37℃)及亚低温(33℃)短暂性全脑缺血模型,进行HE染色、髓过氧化物酶(MPO)活性和P-选择素mRNA及其蛋白表达的测定。结果:亚低温可抑制脑缺血再灌注后P-选择素mRNA及其蛋白的上调、MPO活性和白细胞的浸润。结论:P-选择素的上调与再灌注后炎症性损伤相关。亚低温可抑制P-选择素的表达,减轻再灌注后炎症反应。     

老年人腹部手术术中保温对术后苏醒的影响及护理

目的观察术中保温对老年患者术后苏醒的影响。方法选择全麻开腹手术患者60例(美国麻醉医师协会的分级标准I~Ⅱ级),按照随机数字表法分为常规组和保温组各30例。常规组行常规护理,术中未采取任何保温措施;保温组术中注意保温,室内温度维持在23~28℃,使用Warm Touch TM充气式保温装置及电子液体加温仪,冲洗液用水温浴箱加温至37℃。比较两组患者术前、术中及术后血压、心率、体温的变化及拔管时间、清醒时间、寒战和躁动的发生率。结果(1)常规组患者术中及术后血压、心率、体温与术前相比均存在统计学差异,而保温组患者无明显变化;(2)与保温组患者相比,常规组患者术后血压升高、心率增快、苏醒延迟、寒战及躁动发生率高(P<0.05)。结论术中低体温可影响神经、内分泌和循环系统,延缓患者的术后恢复,增加不良反应发生率;术中应监测体温变化,对输液液体及冲洗液加温,下半身使用保温毯保暖,并保持手术间温度,以缩短患者术后苏醒时间,降低不良反应的发生率。     

亚低温治疗对重型颅脑损伤患者血中神经元特异性烯醇化酶的影响及其临床意义

目的观察亚低温治疗后重型颅脑损伤患者血中神经元特异性烯醇化酶(NSE)的动态变化,为评价亚低温的脑保护作用提供量化指标。方法45例重型颅脑损伤患者被随机分为亚低温治疗组(22例)和常温治疗组(23例),脑温分别控制在(34．2±0．2)℃和(36．9±0．3)℃。动态监测患者治疗前及治疗后24、48、72、96 h血中NSE变化,并于3个月后对患者预后进行评估。结果亚低温治疗组患者血中NSE浓度在治疗后24、48、72 h显著降低．3个月后预后显著改善。结论亚低温治疗可以减轻神经元损伤,显著抑制NSE释放,增强神经元对脑外伤的耐受性,对重型颅脑损伤患者具有保护作用。     

亚低温减少和延迟缺血再灌注后沙土鼠海马CA1区细胞凋亡

目的 研究亚低温对沙土鼠全脑缺血再灌注损伤海马CA1区细胞的保护作用，并探讨其机制。方法 采用沙土鼠全脑缺血再灌注损伤模型，用免疫组织化学方法，动态观察Bax、细胞色素C（CytC）、TUNEL阳性细胞等在常温组、亚低温组及假手术组的表达和变化。结果 与常温组相比，亚低温组CA1区各时间点凋亡细胞数显著减少，且其凋亡高峰延迟。Bax在3h、6h、1d3个时间点CA1区表达较常温组明显减少，且表达高峰延迟，CytC的动态变化与Bax一致。结论 亚低温能减少和延迟细胞凋亡，其机制可能与降低并延迟促凋亡蛋白Bax的表达和线粒体释放CytC有关。