脑死亡的确定

一般认为死亡是呼吸和循环的不可逆性停止，但是，机械通气和心血管支持等手段的应用对如何决定严重脑损害患者生命的终点提出了挑战。作者概括了决定脑死亡最新证据的指南。脑死亡的临床判定标准　临床确定脑死亡的基本条件是：（１）有严重急性大脑意外损伤的临床证据或神经系统影像学证据符合脑死亡诊断；（２）除外其他可能混淆的脑死亡判断（如急性代谢障碍或内分泌失调）；（３）确定无药物中毒；（４）体温≥３２℃。判定脑死亡的确诊试验　虽然确诊试验在大多数情况下并不是必须的，但在决定脑死亡的主要证据可信度不高时，这些附加…     

阿托吕试验在深昏迷至脑死亡过程中的诊断意义

196 8年美国哈佛大学医学院最先提出了脑死亡的概念 ,并确立了脑死亡诊断标准[1] 。我国从 70年代开始探讨脑死亡诊断标准 ,但目前国内尚无正式的脑死亡诊断标准和法律规定。脑死亡即全脑机能不可逆地停止 ,现代医疗条件可以使脑死亡患者靠机械装置长期维持心跳和呼吸 ,但脑死亡是不可逆转的 ,有关抢救措施是徒劳的 ,对国家、医院、家庭带来沉重负担。因此迫切需要及时准确地作出脑死亡的诊断。阿托品试验在 1977年英美联合协作研究组制定的脑死亡诊断标准中视为确诊试验[2 ] 。阿托品试验对脑死亡诊断的价值国内虽有报道[3 ] ,但国内外对阿…     

动态脑电图对脑死亡诊断的应用价值

随着医学科学的发展进步，人类文明不断进步，脑死亡作为个体死亡的标志正在被大家逐步接受，且随着器官移植的快速发展，脑死亡的早期诊断越来越重要，动态脑电图监测在脑死亡的诊断方面起着重要作用。本文收集2001年1月至2005年10月我院住院深昏迷病人27例进行动态脑电图监测分析，探讨脑死亡诊断中的价值。现报告如下：     

脑死亡的诊断

在不同的历史阶段,死亡的概念及死亡的标准是不同的,甚至在同一阶段,不同的国家之间亦有显著差异,在国内乃至全球至今尚无统一的标准。１　死亡的概念传统的死亡概念为心跳呼吸停止。１９６７年别那特（Ｂｅｒｎａｄ）开创了心脏移植先例［１］,对传统的死亡概念提出了挑战,促成了脑死亡诊断标准的形成。脑死亡即全脑机能不可逆地停止。这一概念迅速被各国接受的理由之一是因为符合脑死亡诊断标准的患者在短期内心脏已经不可逆停止。但是由于医学进步、临床经验、社会变化、脏器复苏的新方法等对脑死亡概念亦提出了疑问,如有几例脑死…     

脑死亡临床诊断实施研究18例

目的 :探讨脑死亡临床诊断的实施及其意义。方法 :对 18例脑死亡的病人实施脑死亡临床诊断 ,同时进行SPECT和部分行EEG检查。结果 :临床诊断脑死亡 18例 ,并于 2～ 72h行SPECT检查 ,颅内无灌注 16例 ;同时7例行EEG检查 ,6例呈直线。脑死亡临床诊断后 1d内 ,有 77.8% ,3d内 ,有 94.4%病例的亲属要求停呼吸机终止抢救。结论 :( 1)脑死亡诊断可依临床诊断为主要依据 ,SPECT及EEG可作为脑死亡临床诊断的客观指标 ;( 2 )在城市实施脑死亡临床诊断有较好的社会基础 ,可得到死者家属的支持、理解和认可。     

脑死亡临床诊断步骤的比较研究

脑死亡临床诊断步骤的比较研究上海医科大学华山医院急诊科夏志浩，杨涵铭上海医科大学华山医院神经外科杨伯捷，徐启武脑死亡概念和临床诊断标准，付之临床实施已近３０年，其定义、病因、病理生理和病理解剖、临床研究和律法均有很广泛深入的研究，其临床诊断步骤也有很...     

脑死亡后器官损献者的器官护理

当一个患者被宣布脑死亡的时候；护理人员应继续维持患者血流动力学的稳定，以保持移植器官的存活。因此，作为一名护理人员。最重要的是了解成人脑死亡的指征和潜在器官捐献者的确定，以及脑死亡出现后主要的生理病理改变相关的护理干预本质。     

阿托品试验在脑死亡诊断中的价值

为探讨阿托品试验在脑死亡诊断中的价值，对７例呼吸心跳骤停经心肺复苏心跳恢复用呼吸机维持的病人，当ＧＣＳ评分〈５分开始，每隔６小地作阿托品试验，脑干反射检查，动脉血气分析，并连续心电图，血压，动态脑电图监测，结果：５例脑死亡，阿托品试验都阴性，深昏迷时阿托品试验都阳性，脑死亡时阿托品试验增加心率次数与深昏迷时比较，两者差异显著（Ｐ〈０．００１），提示每隔６小时作阿托品试验，连续２次阴性结果可作为脑死     

脑死亡及其法医学意义

脑死亡（Brain Death）是1968年才明确提出的现代死亡概念。脑死亡不仅是医学、法医学的重要课题，还涉及法律，哲学及伦理学等多门学科，因此引起世人瞩目。脑死亡是指全脑死亡，其提出具有必然性。目前世界上30多个国家或地区从法律上或医学上承认脑死亡为人的个体死亡，脑死亡立法具有医学和社会学的双重意义。     

脑死亡的临床诊断

1959年法国的Mollarct等首先提出脑死亡的概念。他们把对外界没有反应、脑机能丧失,但在人工呼吸支持下维持着心肺功能的患者称为过度昏迷或/及脑死亡。1973年第8次国际脑波学会叙述了如下脑死定义:“脑死是包括小脑、脑干,第一颈髓在内的全脑功能的不可逆性丧失,即采取什么措施都不能使其恢复的状态。导致脑死亡的原因可归纳为二类:一是脑自身的急性原发性严重病变。如:脑外伤,出血,占位性病变等。二是继发性脑病变。如:窒息,心跳停止,中毒等。上述两类引起脑损伤的机理各异,但都可以致脑组织代谢异常,脑水肿而致颅内高压,其结果是颅内血液循环停止。这是脑死亡的主要原因,其次是神经组织由于缺血,发生无菌性自融。     

Using the brain criterion in organ donation after the circulatory determination of death

The UK, France, and Switzerland determine death using the brain criterion even in organ donation after the circulatory determination of death (DCDD), in which the United States and Canada use the circulatory-respiratory criterion. In our analysis of the scientific validity of the brain criterion in DCDD, we concluded that although it may be attractive in theory because it conceptualizes death as a unitary phenomenon, its use in practice is invalid. The preconditions (ie, the absence of reversible causes, such as toxic or metabolic disorders) for determining brain death cannot be met in DCDD. Thus, although brain death tests prove the cessation of tested brain functions, they do not prove that their cessation is irreversible. A stand-off period of 5 to 10 minutes is insufficient to achieve the irreversibility requirement of brain death. Because circulatory cessation inevitably leads to cessation of brain functions, first permanently and then irreversibly, the use of brain criterion is unnecessary to determine death in DCDD. Expanding brain death to permit it to be satisfied by permanent cessation of brain functions is controversial but has been considered as a possible means to declare death in uncontrolled DCDD.     

Bench-to-bedside review: When is dead really dead – on the legitimacy of using neurologic criteria to determine death

This review explores the legitimacy of the whole brain death (WBD) criterion. I argue that it does not fulfill the traditional biologic definition of death and is, therefore, an unsound clinical and philosophical criterion for death. I dispute whether the clinical tests used to diagnose WBD are sufficient to prove all critical brain functions have ceased, as well as examine the sets of brain functions that persist in many WBD patients. I conclude that the definition of death must be modified from a biologic to an ontologic model if we intend to maintain the WBD criterion.     

Bench-to-bedside review: When is dead really dead – on the legitimacy of using neurologic criteria to determine death

This review explores the legitimacy of the whole brain death (WBD) criterion. I argue that it does not fulfill the traditional biologic definition of death and is, therefore, an unsound clinical and philosophical criterion for death. I dispute whether the clinical tests used to diagnose WBD are sufficient to prove all critical brain functions have ceased, as well as examine the sets of brain functions that persist in many WBD patients. I conclude that the definition of death must be modified from a biologic to an ontologic model if we intend to maintain the WBD criterion.     

Bench-to-bedside review: when is dead really dead--on the legitimacy of using neurologic criteria to determine death

This review explores the legitimacy of the whole brain death (WBD) criterion. I argue that it does not fulfill the traditional biologic definition of death and is, therefore, an unsound clinical and philosophical criterion for death. I dispute whether the clinical tests used to diagnose WBD are sufficient to prove all critical brain functions have ceased, as well as examine the sets of brain functions that persist in many WBD patients. I conclude that the definition of death must be modified from a biologic to an ontologic model if we intend to maintain the WBD criterion.     

Rethinking brain death.

OBJECTIVE: To evaluate whether current criteria for the diagnosis of brain death fulfill the requirement for the "irreversible cessation of all functions of the entire brain, including the brainstem." DATA SOURCES: Clinical, philosophical, legal, and public policy literature on the subject of brain death. DATA EXTRACTION/SYNTHESIS: We advance four arguments to support the view that patients who meet the current clinical criteria for brain death do not necessarily have the irreversible loss of all brain function. First, many clinically brain-dead patients maintain hypothalamic-endocrine function. Second, many maintain cerebral electrical activity. Third, some retain evidence of environmental responsiveness. Fourth, the brain is physiologically defined as the central nervous system, and many clinically brain-dead patients retain central nervous system activity in the form of spinal reflexes. We explore options for resolving these inconsistencies between the conceptual definition and the clinical criteria used to make the diagnosis of brain death. CONCLUSIONS: Brain death is a valid conception of death because it signifies the permanent loss of consciousness. Brain death criteria should therefore be based on the diagnosis of the permanent loss of consciousness rather than that of the loss of vegetative brain functions. Revision of our current "whole brain" definition of brain death to a "higher brain" standard should be considered.     

Brain death assessment using instant spectral analysis of heart rate variability

OBJECTIVE: Confirmation of brain death requires an urgent diagnosis to allow rapid vital organ removal for transplantation. Evaluation of forebrain functions is commonly performed through electroencephalogram. Nevertheless, there are, for the moment, no methods that allow for an instantaneous evaluation of brainstem functions. During acute brain injury, heart rate variability is an independent neurologic prognosis indicator resulting from a close relationship between brain stem and cardiac autonomic nervous system. This study aims to evaluate a new heart rate variability spectral analysis method, on a beat-to-beat basis, continuously over the time, during brain death. DESIGN: Prospective, nonrandomized, observational study. SETTING: Intensive care unit. SUBJECTS: Ten patients (age range 25-64 yrs, mean age 41 yrs) with acute brain injury leading to brain death. INTERVENTION: No intervention beyond standard of care MEASUREMENTS AND MAIN RESULTS: Heart rate, arterial blood pressure, heart rate variability in time and frequency domains method, which included calculation of the instant center frequency of spectrum. Brain death was associated with tachycardia (R-R interval 703 +/- 69 vs. 551 +/- 34 msec, p <.05), dramatic reduction of the global spectral power (44.919 +/- 31.511 vs. 3.204 +/- 1.469 msec(2), p <.05), and an abrupt shift of instant center frequency to a higher frequency range (0.17 +/- 0.01 vs. 0.26 +/- 0.03 Hz, p <.05). CONCLUSIONS: Such a method allows an instant, noninvasive determination of brainstem death based on a time and frequency domain analysis of heart rate variability.     

Gestion du donneur d’organes pédiatrique

Paediatric transplantation suffers from a real shortage of compatible organs which is not compensated by attribution priorities, particularly in the case of small children. Paediatric organ recovery should be given more importance by optimizing the intensive care of potential organ donors and family counselling. Brain death is a clinical diagnosis made in the presence of complete and irreversible cessation of all brain functions, after identification of a compatible aetiology. The irreversible status of brain death can be confirmed by two isoelectric and non-reactive electroencephalograms, performed in strict conditions or based on cerebral angiography. Once brain death is confirmed, intensive care aims maintaining haemodynamic parameters, to protect organs instead of brain function. Procedures leading to the diagnosis of brain death in children as well as systemic intensive management of small donors should be well-known and accepted by each member of the caring team. This strategy aims at allowing the participation of the whole caring team and obtaining parents’ confidence and consent for donation.     

Cardiovascular changes in the terminal stage of disease

In 11 patients with brain death, we measured cardiovascular parameters until cardiac arrest. After withdrawal of vasopressors, we observed marked falls in the cardiac output, systemic vascular resistance, heart rate and arterial pressure. In consequence, there was a marked decrease in oxygen delivery and the fall in arterial pressure established a vicious circle and circulatory death ensued. Most pronounced changes were left heart dysfunction and a fall in systemic vascular resistance. On the other hand, depression of the right side of the heart was half of that of left side, and the pulmonary circulation and volume status were well maintained until death. At the same time we found in these patients that body temperature and organ function except that of the brain were well maintained in brain dead patients. For resuscitation of apparently dead patients one must maintain not only cardiac functions but also systemic vascular functions.     

Natural history of global and critical brain ischaemia Part II: EEG and neurological signs in patients remaining unconscious after cardiopulmonary resuscitation

Of 125 patients who had no detectable cortical activity (DCA) on the electroencephalograph (EEG) immediately upon resuscitation from circulatory arrest of primary cardiovascular aetiology, 88 remained unconscious; these patients had their EEG and neurological status serially investigated until they died. Immediately upon re-establishment of circulation all cerebral functions could be absent; the brain death (irreversible loss of functions) was then signified by the appearance of poikilothermia, diabetes insipidus and reflex extension of the upper limb. Most often, some cranial nerve reflexes were present; the EEG configurations and related neurological signs then appeared in a sequence which resembled orderly postischaemic recovery: A phase without DCA was at first characterized by an exclusive presence of cranial nerve reflexes and then by the appearance of decerebrate posturing this phase was followed by another phase of intermittent cortical activity (ICA) with decorticate and stereotypic motor responses and a phase of continuous cortical activity (CCA) accompanied by stereotypic reactivity. These phases were most often incomplete due to failure of recovery of some cranial nerve reflexes or were abnormal due to the appearance of intermittent spikes and sharp waves. Progressive recovery could stagnate at any step and the cerebral functions be lost abruptly or gradually in reverse order of recovery. The decay was invariably due to cardiovascular or pulmonary complications. Brain autopsy revealed extensive neuronal loss and intravital autolytic changes in patients who had fulfilled clinical criteria of brain death for more than 72 h, but the histopathology showed no relationship to other clinical findings during the postischaemic course.     

Brain death, the pediatric patient, and the nurse

The term "brain death" has ties to medical, legal, ethical, and philosophical discourse, and is therefore a complicated and potentially ambiguous term. Some state that with brain death a person no longer has a "master regulating" organ integrating his or her organism as a whole, and the proponents of this view equate this loss of integration with clinical death. Others believe this is not a tenable reason to deem an individual who is brain dead as clinically dead; thus, controversy exists surrounding this issue, and nurses are not resistant to this debate. Whether one supports the definition of brain death as clinical death or not appears to depend on one's view of the mind-body relationship. Pediatric nurses are involved in this controversy because of the care they provide to both the affected child and family in this troubling time.