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Brain Death

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Calixto Machado
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Wijdicks wrote a remarkable historical article revisiting the Transatlantic discussion on the British-American (UK-US) divide on brain death-determination of death by neurological criteria (BD/DNC) by approaching the original contributions of two main inspiring pioneers in this field: Christopher Pallis and Julius Korein. I had the opportunity of maintaining a close personal and scientific relationship with both Professors. Hence, I want to add some remarks to this historical approach and review and discuss that posterior fossa lesions are the main reason to explain the UK-US divide in BD/DNC determination. Pallis attended my First International Symposium on Brain Death, held in Havana, Cuba, in September 1992. His lecture "Brainstem Death" impacted the auditorium. He afterward published a paper with his opinions about that Conference. Pallis strongly articulated the "brainstem death" view. Korein attended my Second Symposium on Brain Death and Disorders of Consciousness (Havana, 1996). His lecture at that Conference on the historical and scientific evolution of the concept of BD/DNC impacted the audience with his pioneering views and thoughts about human death. We developed together (Korein and I) our hypothesis that modifying the "Critical System of the Organism" concept is required since we can further reduce the critical structure of the brain itself to the cortical-cerebral-thalamic- reticular complex. From a practical view, I consider that intracranial pathology in the posterior fossa is the most important topic of controversy in the UK-US debate on BD/DNC determination. When a posterior fossa lesion does not provoke a significant augmentation of intracranial pressure in some patients who fulfill clinical BD/DNC criteria, remaining cerebral blood flow may be present, which explains why EEG, evoked potentials, and autonomic functions are preserved. I concluded that contentious suspected brain-dead cases with primary posterior fossa lesions, such as Jahi McMath, bring us again to discuss the need to use ancillary tests in BD/DNC confirmation
Calixto Machado
added 2 research items
Dr. Calixto Machado was the first Cuban neurologist who was nominated as a Corresponding Fellow. of the American Academy of Neurology (AAN) in 1992. In 2005 Dr. Calixt Machado was bestowed with the American Academy of Neurology “Lawrence McHenry Award”. This was the first time that a Hispanic neurologist, and a neuroscientist from a developing country, received this recognition
Durante siglos, la ausencia irreversible de la función cardio-respiratoria espontánea se consideró como determinante de la muerte del individuo. Sin embargo, con el desarrollo de la terapia intensiva, las funciones integradas en el encéfalo comenzaron a ser consideradas como la razón principal para enunciar una definición de la muerte humana. Existen tres grandes tendencias o escuelas con relación a la definición de la muerte en el hombre sobre bases neurológicas: aquellas que se refieren a la pérdida de atributos esenciales que identifican la naturaleza humana, aquellas que se refieren a la pérdida de la integración del organismo como un todo, y aquellas que tratan de definir la porción del encéfalo que debe cesar de funcionar irreversiblemente para que una persona pueda declararse fallecido. Estas definiciones de la muerte orientadas hacia las funciones encefálicas se discuten, y se llega a la conclusión de que la conciencia (considerando sus dos componentes: capacidad y contenido), cuyas bases neurales se ubican en la llamada unidad formación reticular/corteza, es la función que provee los atributos esencialmente humanos, y a la vez integra el funcionamiento del organismo como un todo. Por tanto, la muerte humana se define como: La pérdida irreversible de la capacidad y del contenido de la conciencia.
Calixto Machado
added a research item
Le May et al. conducted a randomized clinical trial including 367 adults with out-of-hospital cardiac arrest, concluding that a target temperature of 31 °C did not significantly reduce the rate of death or predict poor neurologic outcome at 180 days compared with a target temperature of 34 °C.1 Hypothermia is the best-known method to protect the brain and bodily organs against the effects of ischemia and anoxia. The advantage of hypothermia treatment has also been supported by reports of patients suffering from accidental hypothermia (e.g., immersion/submersion in cold water, snow avalanche, or exposure to cold surroundings) combined with circulatory arrest or severe circulatory failure during long periods.2 Safar documented it in dog experimental models of prolonged exsanguination brain and organ preservation during cardiac arrest (no-flow) durations for up to 120 minutes.3 Therefore, it seems contradictory that therapeutic hypothermia (TH) is ineffective in improving neurologic outcomes and survival. We need to discuss several caveats, such as accurate and early recognition of cardiac arrest, prompt initiation of high-quality CPR, early defibrillation, and rapid activation of emergency medical services (EMS).4 Another essential consideration is that there may not be a single, optimum target temperature for all cases with cardiac arrest because many clinical variables could temper the TH treatment effect.1 Moreover, the duration of resuscitation efforts, defined as low-flow time, influences the effectiveness of TH in terms of neurologic outcome. Patients with low to moderate low-flow time benefit most from this treatment.4 The human brain uses approximately 20% of the cardiac output so that cerebral blood flow (CBF) is tightly regulated to meet the brain’s metabolic demands. The CBF dropping to less than 20 mL/ 100 gm/min produces reduced ischemic neuronal activity but reversible neuronal changes. CBF values less than 10 mL/ 100 gm/min result in irreversible ischemic neuronal damage within minutes, as reflected by membrane failure. That is why the CBF values between 10 and 20 mL/100 gm/min are considered the ischemic penumbra and represent neuronal tissue that may potentially be rescued. Therefore, even when resuscitation attempts in cardiac arrest are successful, recovery is too often limited by anoxic encephalopathy. The potential danger of this complication increases with the delay in resuscitation, and then the prognosis for comatose survivors of cardiac arrest is frequently poor.2 4 Although it is technically challenging, TH should be begun even during CPR and continue in ambulances and emergency medical services.2 The brain is the target organ in cardiorespiratory reanimation.4
Calixto Machado
added a research item
La muerte encefálica (ME) se basa en un diagnóstico clínico, y se acepta como sinónimo de muerte del individuo.1-6 Se llega a este estado cuando una lesión catastrófica provoca un coma irreversible, con ausencia de reflejos de tronco encefálico y apnea, aunque puede ocurrir con lesiones primarias del tronco encefálico sin una elevación importante de la presión intracraneana (PIC). El mantenimiento de la hemodinamia y la oxigenación mediante vasopresores, vasopresina, y la ventilación mecánica, permiten que se mantenga la viabilidad de órganos y tejidos, mientras el encéfalo sufre un proceso de necrosis total.2,5-25 Ingvar señaló que en la ME existía un infarto encefálico total
Calixto Machado
added a research item
The World Brain Death Project addresses discrepancies in clinical guidelines across different countries and focuses attention on the need for better education and certification of clinicians who are authorized to make this clinical diagnosis. The World Brain Death Project published an outstanding paper formulating a consensus statement of recommendations on the determination of brain death/death by neurologic criteria (BD/DNC). Now, Lewis et al particularized analysis of brain death/death by neurologic criteria (BD/DNC) protocols in Africa and found that the percentage of countries with BD/DNC protocols is much lower in Africa than in other developing regions. This is the largest assessment up to the present time about the prevalence of BD/DNC protocols in that continent. The authors also affirmed that, compared with Africa, the proportion of countries with BD/DNC protocols in Latin America/the Caribbean and Asia/the Pacific is similar to that of the world in general. In Africa, hundreds of religions are recognized. In Cuba, the Yoruba religion is very common [1]. Santería was developed in Cuba and then spread throughout Latin America and the United States. Santería was brought to Cuba by people of the Yoruban nations of West Africa (mainly from the actual territory of Nigeria), who were enslaved in great numbers in the first decades of the 19th century. It arose through a process of syncretism between the traditional Yoruba religion of West Africa, the Roman Catholic form of Christianity, and Spiritism. Curiously, although Santeria and Christian religions are common in Cuba, contrary to Africa, most people accept BD/DNC and organ donation. It is also important to consider many African countries lacking primary and essential medical services, which makes the establishment of BD/DNC and organ donation protocols more difficult.
Calixto Machado
added a research item
The RUDDA affirms that the “medical standards” should be based on the AAN guidelines, (1) but it is necessary to discuss the use of ancillary tests, especially in primary posterior fossa lesions. Although Jahi McMath fulfilled clinical DNC criteria, the preservation of intracranial structures, EEG over 2 μV, conservation of HRV components, and autonomic reactivity response to the “mother talks” stimulus, demonstrated remaining brain function in both brainstem and cerebral hemispheres, rejecting that she was braindead.(2) The inferior hypophyseal arteries branch off the extradural segments of the internal carotids are protected from augmented intracranial pressure, and then pathologic studies have demonstrated that the hypothalamus-pituitary region has mild or non-ischemic lesions in braindead cases. As Shewmon emphasized, hypothalamic functions are more significant to the functioning of the “organism as a whole” than any of the brainstem reflexes.(3) This issue requires more academic and medical discussion. (2) Pallis emphasized that the ascending reticular formation gives rise to a generalized activation of the cortex, producing the necessary arousal (capacity for consciousness, but In fact, two physiological components control conscious behavior: arousal and awareness.(4) The RUDDA paragraph (1) should be corrected in a way like this: “irreversible cessation of functions of the entire brain, including the brainstem, leading to unresponsive coma with loss of both components of consciousness (arousal and awareness),…..”. Dr. Machado proposed a new standard of human death.(4) • Definition: Irreversible loss of both components of consciousness which provide the key human attributes and the highest level of control in the hierarchy of integrating functions within the human organism. • Anatomical substratum: Irreversible destruction of the anatomic and functional substratum throughout the whole brain, for the generation of both components of consciousness (arousal and awareness). Relative’s permission to demonstrate DNC is related to the apnea test (AT). Regarding the AT, there are two opposite directions. Those who defend that if the AT is performed using a specific procedure it is completely safe. (5) Other authors assure that the AT is totally dangerous. (3) The AAN guidelines affirm that if an AT cannot be done or has to be aborted, DNC can still be performed by ancillary tests. (5) Hence, a practical solution would be to include ancillary tests in DNC and leave the AT as the last procedure. We agree with the RUDDA (1) that families should not have the legal authority to refuse the medical decision to perform DNC.
Calixto Machado
added a research item
Matiello et al.1 discussed the use of teleneurology (TN) to offer neurologic consultations on the determination of death by neurologic criteria (DNC), a crucial topic of discussion during the current pandemic. Patients' care was mainly the responsibility of fellowship-trained intensivists, which may explain why 42% did not fulfill BD/DNC criteria. Therefore, bedside examiners should have the training to reliably perform a full neurological examination, with an emphasis on the exploration of brainstem reflexes and a satisfactory apnea test. For this reason, it is essential to have a neurologist among the ICU examiner's staff.1, 2 In order to effectively consult these patients virtually, a high-definition camera is required of the technological platform to avoid confusion during exploration of brainstem reflexes, identify the possible presence of respiratory efforts during the apnea test, and differentiate spinal reflexes from myoclonic movements.1, 3 According to AAN Guidelines, DNC determination is mainly based on a clinical assessment, although special conditions require the use of confirmatory tests.4 Hence, bedside examiners should also be trained to perform ancillary tests.3 I applaud the efforts of Matiello et al.1 for providing a telehealth consultation method to facilitate the determination of BD/DNC—a diagnosis which many physicians lack training and experience.
Calixto Machado
added a research item
Nota: Estos lineamientos se publicaron en el año 1992. Como fueron las bases para que la Comisión Nacional para el Diagnósitico de la Muerte en Cuba redactara y propusiera al Ministro de Salud la "Resolución 90 de Salud", que legaliza en el territorio nacional el diagnóstico y la determinación de la muerte, creo que es importante que se conozca por los lectores, con vistas a conocer el desarrollo histórico de aceptar concepto de que la muerte encefálica es sinónimo de muerte del individuo. Mantuve la redacción original del año 1992, así como las referencias bibliográficas. Dr. Calixto Machado Curbelo (Autor principal) La Habana, mayo 3 de 2021
Calixto Machado
added 2 research items
The authors affirm that single brain death (SBD) suffices, favoring organ donation outcomes.1 However, whether to use ancillary tests in BD/DNC confirmation raises further discussion.2 The 2010 AANPP affirmed that BD/DNC is based in a clinical diagnosis, and ancillary tests are only recommended when specific components of the clinical testing cannot consistently be assessed.3 In some patients fulfilling clinical BD/DNC criteria with primary posterior fossa lesions there may not be a total absence of cerebral blood flow, if the posterior fossa lesion does not provoke a sufficient increment of intracranial pressure. This may explain the preservation of EEG activity, evoked potentials, and autonomic function.4 An SBD exam may shorten the grieving period for families. Ancillary tests can also prevent diagnostic confusion for patient’s relatives and the medical staff.4 In addition, shortening the necessary duration for BD/DNC confirmation has a noted economic impact.1, 2, 4 I proposed early in the 1990’s the use of ancillary tests for an early diagnosis of BD/DNC.2 I do agree with Varelas et al. that SBD should be enough for BD/DNC confirmation1 and increasingly so, if the clinical diagnosis is supported by ancillary tests—either those which confirm absent CBF, or those confirmative of absent bioelectrical activity.2, 4,5
Darby et al. discussed if telemedicine technology (TT) can be reliably used for the determination of brain death/death by neurologic criteria (BD/DNC).1 It is necessary to discuss several possible caveats. Of course, the remote examiners should be experienced and well-informed specialists in the BD/DNC diagnosis. To fulfill the clinical assessment to diagnose BD/DNC, bedside examiners should have a training to reliably perform a full neurological examination, with emphasis in the exploration of brainstem reflexes, and to adequately perform the apnea test, even if they are under remote examiners’ surveillance. General practitioners, and physicians from other medical specialties, usually don’t have this necessary training.2,3 Another important issue is the use of ancillary tests. Although according to the American Academy Guidelines BD/DNC determination is mainly based on a clinical assessment,4 there are special conditions, such as primary posterior fossa lesions, requiring the use of confirmatory tests.2,4 Therefore, bedside examiners should be trained to perform ancillary tests.2 Substantial variability in BD/DNC protocols remains worldwide.4 Therefore, although I applaud the efforts of Darby et al.1 for applying TT in the determination of BD/DNC, which achieves a crucial importance in current times, I consider that this new approach of BD/DNC diagnosis should be cautiously approached.
Calixto Machado
added 2 research items
We reported a case (Case 3 in our paper), 1 contributing to the discussion of using ancillary tests in brain death (BD). 2 This case showed BD clinical features, leading to a death certification. We studied the case 9 months later (1). We found preservation of intracranial structures, with a huge lesion at the brainstem.1 Conceptually, BD is characterized by a complete absence of cerebral blood flow.3 Conservancy of brain structures rejects BD diagnosis (1, 3). EEG was found in this case. EEG may persist in posterior fossa catastrophes (2). Using heart rate variability (HRV) methodology, we found preservation of all HRV bands, contrary to reports in BD.4 This case also showed autonomic reactivity to "Mother Talks" stimulation. This is a demonstration of autonomic central nervous system activity preservation (1). Our patient showed BD clinical features, but the use of ancillary tests denied this diagnosis. We claimed that this is a new state, non-previously classified, of a disorder of consciousness (1). Is there actually a diagnosis of any disease in which a confirmatory test (blood test, imaging, etc.) is not used, considering that pitfalls in clinical examination can occur? BD determination is the most challenging diagnosis for a physician Why not to use a confirmatory test? (1, 5).
Jahi McMath has been surely the most controversial suspected brain-dead case. We have been the only group who carefully studied Jahi's brain Preservation of intracranial structures, both in the brainstem and cerebral hemispheres were documented nine months after a cardiac arrest. Conceptually, a brain-dead patient has a complete absence of intracranial cerebral blood flow. Hence, this contradicts a BD diagnosis in Jahi. True EEG was found in this case over 2 μV of amplitude. Moreover, the power spectra analysis showed predominant activity within the delta-theta range. EEG may persist in posterior fossa catastrophes, not producing raised intracranial pressure. Jahi presented a huge lesion at the pons, extending to the medulla. All heart rate variability (HRV) bands were preserved in this patient. BD has been characterized by the loss of all HRV components. This is a demonstration of autonomic activity conservancy in the medulla, within vagal, and other autonomic central nuclei. Another significant finding was the autonomic reactivity, assessed by HRV, to "Mother Talks" stimulation, demonstrating remaining function at different levels of the central autonomic system. These results might explain the video findings reported by Dr. Shewmon, who observed Jahi's movements that he interpreted as responses to commands. Jahi displayed several clinical features of a BD state, but she was not braindead. She was not in coma, because her clinical examination showed a complete absence of brain-stem reflexes, and no spontaneous driving to breath. She was not either in a vegetative state (VS), recently named as unresponsive wakefulness syndrome (UWS) or in a minimally conscious state, because she did not the presence of sleep-wake cycles, and variably preserved cranial-nerve reflexes. Jahi was in a state of disorder of consciousness, not previously described. Considering the continuum of the consciousness spectrum, this state is placed between BD and Coma/VS/UWS. The authors accept that BD is synonym of death, and that in the great majority of cases, clinical examination is enough for BD determination, as affirmed by the American Academy of Neurology, and the Task Force for the Determination of Brain Death in Children. Jahi is a very rare case, resting in an uncommon state of consciousness. This might explain the controversies on her diagnosis. Actually, confirmatory tests are routinely used for the diagnosis of any disease. Ancillary tests will contribute to diminish pitfalls in the diagnosis of brain-dead cases. BD is the most challenging diagnosis for a medical doctor, Why not to use a confirmatory test?
Calixto Machado
added 2 research items
The World Brain Death Project addressed discrepancies in clinical guidelines across different countries on criteria for the diagnosis of brain death, or determination of death by neurologic criteria (BD/DNC), focusing attention on the necessity for better education and certification of clinicians, and formulated a consensus statement of recommendations to diagnose BD/DNC(1). According to my personal experience and research on this topic, and for being immersed on the organization of eight “International Symposia on Brain Death and Disorders of Consciousness” since the early ‘90s, I agree with the authors that substantial variability in BD/DNC protocols worldwide remains, which might partially explain why quarrelsome braindead cases have recently raised up new disputes on accepting BD/DNC(2).
A critical component of this controversy is when intracranial pathology is localized to the posterior fossa. Both supratentorial CBF and EEG may persist when a primary brainstem catastrophe, doesn’t produce markedly raised intracranial pressure. In the presence of a primary supratentorial brain lesion, a severe forebrain lesion is combined with either the subsequent gradual loss of brainstem function due to rostrocaudal transtentorial brain herniation. In the case of a secondary brain lesion (e.g. cerebral hypoxia), the brainstem is also affected like the forebrain. However, in a minority of patients, who have a primary infratentorial brain lesion (for example, in basilar artery thrombosis or large brainstem or cerebellar bleed), may retain CBF and even EEG activity.
Calixto Machado
added a research item
The World Brain Death Project published an outstanding paper formulating a consensus statement of recommendations on determination of BRAIN DEATH/DEATH BY NEUROLOGIC CRITERIA (BD/DNC). According to my personal experience and research on this topic, and for being immersed on the organization of eight “International Symposia on Brain Death and Disorders of Consciousness” since the early ‘90s, I agree with the authors that substantial variability in BD/DNC protocols worldwide remains,1 which might partially explain why quarrelsome braindead cases have recently raised up new disputes on accepting BD/DNC. In fact, the presence of primary posterior fossa lesions enforces the needs to align the criterion and tests for BD/DNC diagnosis. In some patients fulfilling clinical BD/DNC criteria, when a posterior fossa lesion does not provoke an important increment of intracranial pressure there may be not a full absence of CBF, explaining preservation of EEG activity, evoked potentials, and autonomic function in some cases. I comment that this was the case of Jahi McMath. I applaud the effort of the World Brain Death Project in order to formulate a consensus declaration of recommendations on determination of BD/DNC,1 which will undoubtedly contribute to diminish confusion and variability on the worldwide acceptance of BD/DNC as synonym of human death.
Calixto Machado
added a research item
The World Brain Death Project published an outstanding paper formulating a consensus statement of recommendations on determination of brain death/death by neurologic criteria (BD/DNC).1 According to my personal experience and research on this topic, and for being immersed on the organization of eight “International Symposia on Brain Death and Disorders of Consciousness” since the early ‘90s,2 I agree with the authors that substantial variability in BD/DNC protocols worldwide remains,1 which might partially explain why quarrelsome braindead cases have recently raised up new disputes on accepting BD/DNC.3 I also approve the recommendation that the terms “whole brain death” and “brainstem death” should be replaced with BD/DNC, mainly based in the setting of an isolated posterior fossa lesion, when ancillary testing should be performed. In these circumstances, it is important to remark that “BD/DNC should not be diagnosed until supratentorial and infratentorial blood flow is lost, even if the clinical examination and apnea test are suggestive of BD/DNC”.1 It is necessary to state that there are two groups of ancillary tests: those which show no cerebral blood flow (CBF), and those which demonstrate absence of bioelectrical activity.2,4 I don’t agree with the recommendation that “It is suggested that electrophysiologic testing with electroencephalography (EEG) no longer be used routinely as an ancillary test in adults”. On the contrary, I fully agree that “EEG should be used in conjunction with somatosensory and brainstem auditory evoked potentials”. I have recommended a test battery conformed by EEG and evoked potentials to confirm BD/DNC.4 In fact, the presence of primary posterior fossa lesions enforces the needs to align the criterion and tests for BD/DNC diagnosis. In some patients fulfilling clinical BD/DNC criteria, when a posterior fossa lesion does not provoke an important increment of intracranial pressure there may be not a full absence of CBF, explaining preservation of EEG activity, evoked potentials, and autonomic function in some cases.3 Some authors commented that in the case of isolated brainstem lesions, sparing the mesopontine tegmental reticular formation, this condition would theoretically lead to a fully apneic locked-in syndrome, which imitates the so-called “brainstem death”, with the possibility of retaining some degree of consciousness for some time, even fulfilling clinical BD criteria.5 This was the case in Jahi McMath.3 I applaud the effort of the World Brain Death Project in order to formulate a consensus declaration of recommendations on determination of BD/DNC,1 which will undoubtedly contribute to diminish confusion and variability on the worldwide acceptance of BD/DNC as synonym of human death.
Calixto Machado
added a research item
Several research groups have developed protocols for lowering body temperature in comatose survivors of cardiac arrest, resulting in a significant improvement in neurologic outcome. It is logical for mild hypothermia to be used in focal ischemic insults such as stroke, where it could play a neuroprotective role, reperfusion is critical in that condition, and hypothermia should serve as a bridge and/or adjunct in that regard. The plumbing must be addressed in stroke; otherwise, acute therapies cannot be effective. It is necessary to develop and apply neuroprotective methods to prevent brain damage due to anoxia and ischemia and should be initiated as soon as possible after cardiac arrest and maintained even during cardiopulmonary resuscitation.
Calixto Machado
added a research item
It is widely accepted that brain death (BD) is a clinical diagnosis, although ancillary tests are recommended when specific components of the clinical testing cannot reliably be evaluated. The therapeutic use of barbiturates in patients with severe intracranial hypertension or other forms of drug intoxication, hypothermia, and other metabolic disturbances, can prevent determination of BD by clinical criteria. We present a review here about the use of ancillary tests in BD confirmation. Confirmatory tests in BD can be divided in those proving absent cerebral blood flow (CBF) and those that demonstrate loss of bioelectrical activity. We recommend assessing circulatory arrest by transcranial Doppler (TCD), and neuronal function by a neurophysiologic test battery. If TCD fails to validate the absence of CBF, computer tomography angiography can be used to confirm BD diagnosis.
Calixto Machado
added a research item
ntroduction: With the development of the transplants of organs, the diagnosis of brain death (BD) it became valued. The main causes of described BD are cerebrovascular diseases and head injury. In spite of recognized her importance of the donation of organs, numerous they are the factors for its negative. Objectives: To identify the patients with BD, its etiologies and the number of donors of organs. Materials and methods: We accomplished a retrospective study of the 33 medical records of patients with BD diagnosed in one year at the hospital in Curitiba, Brazil. The studied data were sex, age, dates of the diagnosis of the death, etiology, number of donors and the causes of the not donation of organs. Results: 33 patients, 19 male and 14 females with mean age of 37.7 years. The etiologies were head injury with 30%, brain hemorrhage 21%, ischemic stroke 10.3% and accident for firearm 9%. Of the patients studied only 15% were donors, among the non-donors the causes were: it family refuses, hemodynamic instability, positive serology and failure of multiple organs. Conclusion: In Brazil, of the caption centers, Paraná meets in third place. In the year 2001, 343 diagnoses of BD were accomplished in the state. The head injury was the main cause of BD. Therefore, the support of appropriate interdisciplinary team and the precocious diagnosis, generate a larger number of patients potential donors of organs, improving the systematic of transplants in the country.
Calixto Machado
added a research item
Lewis et al.1 developed the largest and most complete assessment ever performed for identifying similarities and differences in protocols on determination of brain death/death by neurologic criteria (BD/DNC). The authors found substantial variability in protocols, which might partially explain why quarrelsome braindead cases have recently raised up new disputes on accepting BD.2,3 The presence of primary posterior fossa lesions enforces the needs of “aligning the criterion and tests for brain death.”4 In some patients fulfilling clinical BD criteria, when a posterior fossa lesion does not provoke an important increment of intracranial pressure, there may be not a full absence of cerebral blood flow, explaining preservation of EEG activity, evoked potentials, and autonomic function in some cases.3 Some authors commented that in the case of isolated brainstem lesions, sparing the mesopontine tegmental reticular formation, this condition would theoretically lead to a fully apneic locked-in syndrome—which imitates brainstem death—with the possibility of retaining some degree of consciousness for some time, even fulfilling clinical BD criteria.5 This was the case in Jahi McMath.3 Further research and discussion are necessary concerning the use or not of ancillary tests in BD diagnosis, in the presence of primary posterior fossa lesions. Disclosure The author reports no relevant disclosures. Contact journal@neurology.org for full disclosures. References Lewis A, Bakkar A, Kreiger-Benson E, et al. Determination of death by neurologic criteria around the world. Neurology 2020 Epub Jun 23. Lewis A. Reconciling the Case of Jahi McMath. Neurocrit Care 2018;29:20–22. Machado C. Jahi McMath: a new state of disorder of consciousness. J Neurosurg Sci 2020 Epub May 13. Bernat JL, Dalle Ave AL. Aligning the Criterion and Tests for Brain Death. Camb Q Healthc Ethics 2019;28:635–641. Walter U, Fernandez-Torre JL, Kirschstein T, Laureys S. When is "brainstem death" brain death? The case for ancillary testing in primary infratentorial brain lesion. Clin Neurophysiol 2018;129:2451–2465.
Calixto Machado
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In this paper, I reviewed the case of Jahi McMath who was diagnosed as being in brain death (BD). Nonetheless, ancillary tests, performed 9 months after initial brain insult, showed conservation of intracranial structures, EEG activity, and autonomic reactivity to “Mother Talks” stimulus. She was clinically in a state of unarousable and unresponsiveness, without evidence of awareness of self or environment, but full absence of brainstem reflexes, and partial responsiveness rejected the possibility of being in coma. Jahi was not a UWS, because she was not in a wakefulness state, and showed partial responsiveness. LIS patients are wakeful and aware, and although these cases are quadriplegic, they fully or partially preserve brainstem reflexes, vertical eye movements, and/or blinking, and respire by their own, rejecting the possibility of classifying her as a LIS patient. She was not a MCS because she did not preserve arousal, and only partially preserved awareness. The CRS-R resulted in a very low score, not corresponding with MCS patients. MCS patients fully or partially preserve brainstem reflexes, and usually breathe by their own. MCS has been always described as a transitional state between coma, UWS, but MCS has never been reported in a patient who has all clinical BD findings. This case doesn’t contradict the concept of BD, but brings again to discussion the needs of using ancillary tests in BD. I concluded that Jahi represented a new state of disorder of consciousness, non-previously described, that I have termed: “responsive unawake syndrome” (RUS).
Calixto Machado
added a research item
Brain death (BD) concept has been increasingly widely accepted beginning since the late 1950s, but several controversies have appeared when intracranial pathology is localized to the posterior fossa. In the presence of a primary supratentorial brain lesion, a severe forebrain lesion is combined with either the subsequent gradual loss of brainstem function, due to rostrocaudal transtentorial brain herniation. In secondary brain lesions (i.e., cerebral hypoxia), the brainstem is also affected like the forebrain. However, a minority of patients with a primary infratentorial brain lesion (i.e., basilar artery thrombosis or brainstem or cerebellar bleeds) may retain cerebral blood flow and EEG activity. In this article I discuss that if a brainstem lesion does not provoke a massive increase of intracranial pressure there may be no complete cerebral circulatory arrest, explaining the preservation of EEG activity, evoked potentials, and autonomic function. I also discuss the case of Jahi McMath who was declared brain-dead, but ancillary tests, performed 9 months after initial brain insult, showed conservation of intracranial structures, EEG activity, and autonomic reactivity to “Mother Talks” stimulus, rejecting the diagnosis of BD. Jahi McMath’s MRI study demonstrated a huge lesion in the pons. Some authors have argued that in patients with primary brainstem lesions it might be possible to find a in some cases partial recover of consciousness, even fulfilling clinical BD criteria. This was the case in Jahi McMath. Further research and discussion are necessary about the use of ancillary tests in BD diagnosis in primary posterior fossa lesions.
Calixto Machado
added a research item
Hypothermia is the best known method to protect the brain against the effects ischemia and anoxia to the brain, and all organs.[3] Moreover, the advantage of the hypothermia treatment is also supported by reports of patients suffering accidental hypothermia immersion/submersion in cold water, snow avalanche or prolonged exposure to cold surroundings) combined with circulatory arrest or severe circulatory failure during long periods of time, who were rewarmed to normothermia by use of extracorporeal circulation, with good outcome in several cases. . But the key point in these cases is that the neuroprotective effect of accidental hypothermia occurred very early, even before a complete cardiac arrest had occurred. Hence, I will focus my commentaries about the effects of hypoxia and ischemia on the brain after cardiac arrest.
Calixto Machado
added a research item
As an American Academy of Neurology {AAN) Corresponding Fellow, I applaud the AAN position statement1because-in recent years-there were a number of controversies in suspected brain death {BD) cases. The Uniform Defemination of Death Act referred to the term "accepted medical standards," but the lack of explicitness and institutional BD protocol variations have contributed to conflicting interpretations by the courts. Nevada became the first US state to revise these disagreements, stating that defemination of death by neurologic criteria must fulfill the AAN guidelines for BD in adults and other guidelines for BD diagnosis in pediatric patients. Other debates in courts include whether apnea testing {AT)is a procedure with substantial risks demanding families' informed consent. Nonetheless, the AT is a relatively simple and safe test when considering the precautions: preoxygenation and tracheal oxygen insufflation.
Calixto Machado
added 2 research items
To the Editor: In a recently published issue of Pediatric Critical Care Medicine, Piantino et al (1) demonstrated that in children with brain injury, lower heart rate variability (HRV) is an early indicator of autonomic system failure, and it predicts progression to brain death. But we propose to consider some methodologic and standardized procedures that we have recently discussed (2, 3). Our group has used the HRV methodology to explore the autonomic nervous system in comatose and brain-dead patients (2, 4, 5). However, HRV indices have shown to be under the influence of multiple demographic and physiologic variables (age, sex, heart rate, blood pressure, and respiratory rate) becoming confounding factors (CFs) that need to be considered in these studies (3). In addition, in patients in coma, the presence of non-Gaussian, nonlinear, and nonstationary processes associated with the multiple mechanisms regulating the autonomic control of the cardiovascular system cannot be ruled out. The traditional approach using the Fourier analysis for the study of spectral components of HRV has been successfully and widely used since its introduction, but strictly speaking, this method is limited to the study of linear systems. One of the well-known methods introduced to analyze nonlinear and nonstationary biomedical signals is the Hilbert-Huang transform (HHT) (2). We studied comatose patients classified into two subgroups according to their Glasgow Coma Scale (GCS): 23 patients with GCS from 6 to 8, and 24 patients in coma with GCS from 3 to 5. A group of 33 healthy participants with ages and sex in the same ranges of the group of patients in coma was considered as the control group. Conventionally, in the study by Estévez-Báez et al (2), the groups were referred to as “Control,” “Glas68,” and “Glas35”. We used a statistical method for the adjustment of HRV indices to the effects of CFs and correct them when necessary. We also applied the HHT, considering that HRV indices in coma are nonlinear and nonstationary biologic signals. Our most important result was the reduction of HRV observed in comatose patients, which showed a progressive trend associated with deepening of coma, assessed by the GCS. The grand averages of the Hilbert marginal spectra showed a marked reduction of the power spectral density for the 2 group of patients in coma, which was even more intense in the Glas35 group. Second, the peaks of the HRV spectra were progressively not only reduced in magnitude, but almost disappeared in the Glas35 group, particularly for the high-frequency (HF) and low-frequency bands. Third, the appearance of a significant peak in the very HF (VHF) range (0.4–0.6 Hz), particularly evident in the Glas68 group, and only slightly evident in the Glas35 group. This was the first-ever report of the appearance of VHF peaks in coma. HRV indices showed that they can efficiently predict mortality in comatose patients, particularly in the VHF range, which was shown for the first time in the study by Estévez-Báez (2). This deserves further studies to fully define its pathophysiologic meaning. Methodologic and standardized procedures described in this study should be considered in future investigations. The authors have disclosed that they do not have any potential conflicts of interest.
Abstract Lewis et al. published an important and timely necessary article about the determination of death by neurological criteria, revising the Uniform Determination of Death.The acceptance of brain death (BD) has been progressively accepted beginning at the late 1950s. Nonetheless, contentious brain-death cases have recently raised new controversies about the diagnosis of BD, such as the Jahi McMath case, extensively covered by the US and international press. Jahi McMath meant a terrible tragedy for her and her family. But further than this gloomy story, the case has also raised confusion and challenging qualms about a fundamental query: how we confirm whether a person is dead or alive? Since 1981, the Uniform Determination of Death Act (UDDA) has served as the legal foundation for the medical practice of determining death. But, although death by neurologic criteria is considered legal death throughout the United States, several recent lawsuits have quizzed the rightfulness the authority of the UDDA to declare death by neurological criteria. This issue explains the importance of Lewis’s et al. paper. In this article I want to present the historical procedure for issuing a law in Cuba for the determination and certification of death. Of course, it is impossible to compare our country with USA. Cuba is a small and developing country, in which a law encompasses a national scenery, in contrast with USA, a multistate nation.
Calixto Machado
added a research item
This survey found substantial variability in brain death (BD) examination,1although theAmerican Academy of Neurology (AAN) guidelines constitute a worldwide bedrock in BDdetermination.2These results aggravate worries to those who face the BD diagnosis.3,4 One-third of respondents reported applying ancillary testing automatically.1 Greer et al.5reported that ancillary tests were mandatory in 6.5%, and EEG was listed in 78.8% of the US institutions. According to the AAN guidelines, ancillary testing should only be used when theclinical examination cannot be completed or an apnea test cannot be performed.2 EEG may persist in posterior fossa catastrophes in patients fulfilling clinical BD criteria. This finding contradicts the whole-brain criterion.3 We recently published the case of Jahi McMath who showed BD clinical features, but the use of ancillary tests denied this diagnosis.4 We claimed that this is a new state, not previouslyclassified, of a disorder of consciousness.3,4 Although Dr. Wijdicks affirmed that“...patients who are clinically dead do not need confir-mation,”6 is there currently a diagnosis of any disease in which an ancillary test is not used? BDdetermination is the most challenging diagnosis for a physician; why not to use an ancillary test?This might reduce BD policies’variability.3,4
Calixto Machado
added 4 research items
Introduction: The current methodologies to study brain function or underlying anatomic structure, separately, do not explain directly how alterations in the anatomical network determine the exchange of information between different brain regions and how these changes relate to development of certain pathologies. The epilepsy is an example of neurological disorder related with both anatomical and functional network damage. Objective: To propose a methodology to integrate neuroimaging and biophysic models to predict neuronal dynamics and to infer brain functioning. Methods: The methodology is applied to six subjects, three patients with temporal epilepsy and three patients with extra-temporal epilepsy. Individuals models for each subjects are built using anatomical connectivity matrix derived from diffusion magnetic resonance imaging. Network properties are used to characterize the clinical hypothesis of epileptogenic zone (EZ). Results: The simulation using individual structural connectivity matrix enabled to describe network dynamics, spatial topology of the network and neurophysiological mechanisms that determine network behavior. Also, the change in functional pattern was studied when regional stimulation or when EZ surgical resection were simulated. Conclusions: Brain simulation is a complementary technique that enables inference on model parameters that reflect mechanisms that underlie emergent behavior. A future application of the proposed methodology could be to identify the optimal surgical strategy based on simulation of effects of different targeted surgical resections. Key words: connectivity, computational modeling, structure-function relationship, epilepsy.
Jahi McMath has been surely the most controversial suspected brain-dead case. We have been the only group who carefully studied Jahi’s brain Preservation of intracranial structures, both in the brainstem and cerebral hemispheres were documented nine months after a cardiac arrest. Conceptually, a brain-dead patient has a complete absence of intracranial cerebral blood flow. Hence, this contradicts a BD diagnosis in Jahi. True EEG was found in this case over 2 μV of amplitude. Moreover, the power spectra analysis showed predominant activity within the delta-theta range. EEG may persist in posterior fossa catastrophes, not producing raised intracranial pressure. Jahi presented a huge lesion at the pons, extending to the medulla. All heart rate variability (HRV) bands were preserved in this patient. BD has been characterized by the loss of all HRV components. This is a demonstration of autonomic activity conservancy in the medulla, within vagal, and other autonomic central nuclei. Another significant finding was the autonomic reactivity, assessed by HRV, to “Mother Talks” stimulation, demonstrating remaining function at different levels of the central autonomic system. These results might explain the video findings reported by Dr. Shewmon, who observed Jahi’s movements that he interpreted as responses to commands. Jahi displayed several clinical features of a BD state, but she was not braindead. She was not in coma, because her clinical examination showed a complete absence of brain-stem reflexes, and no spontaneous driving to breath. She was not either in a vegetative state (VS), recently named as unresponsive wakefulness syndrome (UWS) or in a minimally conscious state, because she did not the presence of sleep-wake cycles, and variably preserved cranial-nerve reflexes. Jahi was in a state of disorder of consciousness, not previously described. Considering the continuum of the consciousness spectrum, this state is placed between BD and Coma/VS/UWS. The authors accept that BD is synonym of death, and that in the great majority of cases, clinical examination is enough for BD determination, as affirmed by the American Academy of Neurology, and the Task Force for the Determination of Brain Death in Children. Jahi is a very rare case, resting in an uncommon state of consciousness. This might explain the controversies on her diagnosis. Actually, confirmatory tests are routinely used for the diagnosis of any disease. Ancillary tests will contribute to diminish pitfalls in the diagnosis of brain-dead cases. BD is the most challenging diagnosis for a medical doctor., Why not to use a confirmatory test?
Aim: Identify the main methodological challenges of EEG signal processing with alternative methods. Methods: The nonlinear, non-Gaussian, and non-stationary properties of the brain processes generating the EEG in healthy subjects are a truly controversial topic. For patients with disorders of consciousness these condition cannot obviously be ruled out. For this reason the use of traditional methods for the EEG analysis using frequency domain methods based in the fast Fourier transform (FFT) are specially limited when applied to the study in these patients. Results: The Hilbert-Huang method has been applied to analyze the EEG signal in the frequency domain. This method has a first step named Empirical Mode Decomposition and a second final step which imply the calculation of different spectral indices using the Hilbert Transform. Preliminary reference values have been calculated and used for the evaluation of the EEG of patients clinically diagnosed with brain death. Conclusion: The Hilbert-Huang Method may be a useful tool for the quantitative analysis of the EEG signal in patients diagnosed with brain death. Key Words: brain death, Hilbert-Huang method, empirical mode decomposition, electroencephalography, qEEG.
Calixto Machado
added a research item
Snider et al. 1 determined that the ascending arousal network (AAn) connectivity is diminished after traumatic brain injury. Nonetheless, in focal lesions of the brainstem, diffusion tensor imaging and white matter tractography can reveal other tract alteration patterns: deviation, deformation, infiltration, and apparent tract disruption. 2 In brain death (BD) diagnosis, intracranial blood flow and EEG may persist in primary brainstem catastrophes. I reported the case of Jahi McMath who was diagnosed as BD, but ancillary tests showed conservation of function in brainstem and cerebral hemispheres and partial awareness. 3,4 Establishing a degree of consciousness is consistent with some preservation of the mesopontine reticular formation and its connections. Therefore, some preservation of consciousness or cortical behavior suggests that this pathway may be partially intact. Thus, the integrity of this pathway should be tested in brain-dead individuals. Other possibility is that this pathway is injured but there is cortical activity. MRI in Jahi showed a huge lesion in the posterior regions of the pons. 5 Probably, the relative intactness of the upper brainstem, thalamus, and cortex could serve as a structural basis for intermittent awareness. 3,4 The AAn method 1 should be applied to explore the pathophysiology of BD and disorders of consciousness in brainstem lesions.
Calixto Machado
added a research item
McGee and Gardiner has published an interesting article about the differences of legal challenges to the concept of brain death (BD) in the USA, Canada and the UK.[1] During the last decades, three main brain-oriented formulations of death have been discussed: whole brain, brainstem death and higher brain standards.[2-5]. James Bernat claimed that “the formulation of whole-brain death provides the most congruent map for our correct understanding of the concept of death”.[6] This author argued that ”.[7] Bernat and his colleagues’ view about the defence of the whole-brain formulation of death was cited by the United States President's Commission for the Study of Ethical Problems in Medicine and Biomedical and Behavioural Research as the conceptual basis of BD.[5,8,9] President's Commission recommended the adoption by all US states of the Uniform Determination of Death Act (UDDA).[10,11] Christopher Pallis articulated the brainstem death view which dismissed the use of EEG or CBF studies as confirmatory tests in BD diagnosis.[12,13] According to McGee and Gardiner,[1] the legal position in the UK is relatively well settled, because the historic Royal Colleges’ Code of Practice, as providing the accepted medical standard for declaring death in the UK.[14] The recognized standard for defining death is death: “the irreversible loss of the capacity for consciousness, combined with irreversible loss of the capacity to breathe and therefore irreversible cessation of the integrative function of the brainstem”.[12-14] The conceptual and practical difference in BD determination between the USA and UK has been known as the "transatlantic divide" in BD determination. [15] A critical condition for this controversy is when intracranial pathology is localized to the posterior fossa. Both intracranial blood flow and EEG may persist when a primary-brainstem catastrophe that does not produce markedly raised intracranial pressure is present. [16-19] Varela et al. recently analysed three cases out of 161 who met inclusion criteria (1.9% of all brain deaths during this period), adding a patient from another hospital.[18] All four patients suffered from catastrophic posterior fossa injuries, and therefore fulfilled the UK BD clinical criteria, including the apnoea test. Those 4 patients showed preservation of supratentorial blood flow, which disappeared after a period of 2 to 6 days, allowing then BD declaration, according to the whole brain criteria, adopted in USA. These authors concluded that patients with primary posterior fossa catastrophic lesions who clinically seemed to be brain-dead according to USA BD criteria would typically evolve from retaining to losing supratentorial blood flow. Therefore, the authors affirmed that if CBF assessment is used as an ancillary test, providing an additional criterion for the declaration of BD, those patients are not different than those who become BD due to supratentorial lesions. Nonetheless, the challenge of the aforementioned cases focuses on determining when the patients were brain-dead according to US or UK BD criteria. According to UK guidelines, patients were brain-dead after the first clinical evaluation but after 6 days all 4 patients were brain-dead according to US guidelines.[20-23] Therefore, in primary brainstem or cerebellar lesions, under the whole-brain formulation, several BD guidelines have stipulated that ancillary electrical and/or blood flow tests are needed to confirm BD diagnosis.[3,20,24-28] I agree with the Bernat et al, [5,8,9] regarding that irreversible cessation of functions of the whole brain is BD, and means death of the individual, because the “brain is responsible for the functioning of the organism as a whole”. McGee and Gardiner also emphasize on the case of Jahi McMath as a reason for BD diagnosis controversies,[1] but this is other story.[20-22] I was able to study Jahi McMath using ancillary tests, 9 months after her initial diagnosis. I did not have access to her initial clinical history.[20-23] Preservation of intracranial structures, both in the brainstem and cerebral hemispheres was documented by MRI, nine months after a cardiac arrest, in spite of vast brain injury. Conceptually, a brain-dead patient has a complete absence of intracranial cerebral blood flow. Hence, this contradicts a BD diagnosis in Jahi. True EEG was found in this case over 2 μV of amplitude. Moreover, the power spectra analysis showed predominant activity within the delta-theta range. EEG may persist in posterior fossa catastrophes, not producing raised intracranial pressure. Jahi presented a huge lesion at the pons, extending to the medulla. All heart rate variability (HRV) bands were preserved in this patient. BD has been characterized by the loss of all HRV components. This is a demonstration of autonomic activity conservancy in the medulla, within vagal, and other autonomic central nuclei. Another significant finding was the autonomic reactivity, assessed by HRV, to “Mother Talks” stimulation, demonstrating remaining function at different levels of the central autonomic system. These results might explain the video findings reported by Dr. Shewmon, who observed Jahi’s movements that he interpreted as responses to commands. Jahi McMath was not in coma, because although she showed a sleep-like state of unarousable, unresponsiveness without evidence of awareness of self or environment; her clinical examination showed a complete absence of brain-stem reflexes and no spontaneous drive to breath (apnoea). This patient was not in either an unresponsive wakefulness syndrome (UWS) or in a minimally conscious state (MCS) state. The reason is that she had not shown intermittent wakefulness manifested by the presence of sleep-wake cycles or variably preserved cranial-nerve. Moreover, usually UWS patients can breathe on their own, without mechanical ventilation. The possibility of being in a MCS and/or MCS emergent states is excluded, because these patients show, upon clinical examination, recovery of cognitive functions.[20-22] Therefore, when I examined her ancillary tests, she was not brain-dead. Therefore, I claimed that this is a new state of disorder of consciousness non-previously classified.[22]
Calixto Machado
added a research item
Muerte Encefálica: Un nuevo enfoque. (Libro) DrCs. Francisco Calixto Machado Curbelo, (braind@infomed.sld.cu) Instituto de Neurología y Neurocirugía, Ciudad de La Habana Introducción Durante siglos, la ausencia irreversible de la función cardio-respiratoria espontánea se consideró como determinante de la muerte del individuo. Sin embargo, con el desarrollo de los cuidados intensivos, sobre todo a partir de la segunda mitad del presente siglo, fue posible suplir aquellas funciones reconocidas hasta ese momento como vitales. Esto creó una verdadera revolución en el concepto de la muerte, cuando la atención se desplazó hacia definiciones basadas en considerar la pérdida definitiva de funciones integradas en el encéfalo, surgiendo así el concepto de muerte encefálica (ME) como muerte del individuo. En nuestro país, debido a la atención que se le ha brindado a la medicina a partir de 1959, ha ocurrido un desarrollo impetuoso de las distintas especialidades médicas. Así, el desarrollo de la terapia intensiva dio lugar a que nuestros especialistas enfrentaran el difícil manejo de pacientes en que evolucionaban hacia el estado de ME. Por otro lado, la trasplantología, inaugurada partir del primer trasplante renal realizado en nuestro país, el 24 de febrero de 1970, hoy en día se sitúa a un nivel que se compara con el de los países más desarrollados. Estos antecedentes dieron lugar a que nuestros especialistas médicos tomaran un interés especial en el diagnóstico de tan controversial estado. Desde los finales de la década de los años '80 el Autor comenzó a desarrollar investigaciones en el Instituto de Neurología y Neurocirugía para lograr un diagnóstico precoz de la ME, y dirigió la Comisión Nacional para la Determinación y Certificación de la Muerte en Cuba, que permitió, por primera vez, dar respuesta al Código Civil Cubano, con la Resolución 90 de Salud Pública que legaliza la determinación y certficación de la muerte a lo largo y ancho de nuestro país. En este año el Autor ha presentado un compendio de los nuevos resultados científicos sobre los aspectos conceptuales, históricos, la definición y diagnósito de la muerte encefálica, como muerte del individuo, así como el estudio de trastornos de la conciencia, tales como el coma, y los estados vegetativos y mínimos de conciencia. Se utilizaron en este estudio técnicas novedosas, como la tomografía eléctrica cerebral
Calixto Machado
added a research item
This survey found substantial variability in BD examination, 1 even though the American Academy of Neurology (AAN) guidelines constitute a worldwide bedrock in brain death (BD) determination. 2 These results aggravate worries to those who face the BD diagnosis. 3,4 One-third of respondents reported applying ancillary testing automatically. 1 Greer et al. reported that ancillary tests were mandatory in 6.5 %, and EEG was listed in 78.8 % of the US institutions. 5 According the AAN Guidelines, ancillary testing should only be used when the clinical examination cannot be completed or an apnea test cannot be performed. 2 EEG may persist in posterior fossa catastrophes, in patients fulfilling clinical BD criteria. This finding contradicts the whole brain criterion. 3 We recently published the case of Jahi McMath who showed BD clinical features, but the use of ancillary tests denied this diagnosis. 4 We claimed that this is a new state, not previously classified, of a disorder of consciousness. 3,4 Although Dr. Wijdicks affirmed that "…patients who are clinically dead do not need confirmation," 6 is there currently a diagnosis of any disease in which an ancillary test is not used? BD determination is the most challenging diagnosis for a physician; why not to use an ancillary test? This might reduce BD policies variability. 3,4 References 1. Braksick SA, Robinson, CP, Gronseth GS, Hocker S, Wijdicks EFM, Rabinstein AA. Variability in reported physician practices for brain death determination.
Calixto Machado
added a research item
Se propone una nueva formulacion sobre la muerte sobre bases neurologica
Calixto Machado
added 5 research items
Introduction and methods. We studied 72 patients fulfilling all the criteria for brain death (BD) by means of a series of tests: brain stem auditory visual evoked potentials (VEP), short latent period somatosensory evoked potentials (SEV) and electroretinogram (ERG). Results. Three characteristic PEATC patterns were identified: bilaterally flat (73.34%), bilateral I wave (16.66%) and unilateral I wave (10%). The N20 wave of the SEV and other later cortical components were not seen in any patients, whilst the so-called subcortical components were partially or totally maintained. The use of non-cephalic data permitted discussion as to the origin of the subcortical components. When cephalic data was used to obtain the ERG and the VEP, the a and b waves of the ERG were recorded in all cases, whilst in the VEP channel waves of inverse polarity appeared of similar morphology and the same latency, but of lower amplitude than those of ERG. When a non-cephalic reference was used, the morphology and latency of the ERG components were unchanged, whilst no response was obtained from the VEP channel. This electrophysiological pattern indicates that the only part of the visual pathway of patients with BD to maintain electrical activity is the retina. Conclusion. The application of this set of tests permits early diagnosis of BD, which is basic for transplantation [REV NEUROL 1998; 27: 809-17]. Key words. Brain death. Confirmatory tests. Electroretinogram. Evoked potentials
Calixto Machado
added a research item
Daneshmand et al. presented a detailed review of 147 patients to answer the question of whether the apnea test (AT) in brain death (BD) determination is a procedure with significant menaces demanding informed consent from patients’ relatives.1 The AT has been considered by most neurologist as the "condition sine qua non" for determining brain death (BD), and the most discriminant test for BD diagnosis.2,3 However, several authors affirmed that AT is not safe because of potential complications, such as severe hypotension, pneumothorax, excessive hypercarbia, hypoxia, acidosis, and cardiac arrhythmia or asystole.1,4 Daneshmand et al. demonstrated that if the AT is performed exactingly following the AAN guideline, it "will mostly be uncomplicated."1
Calixto Machado
added 7 research items
To survey brain death criteria throughout the world. The clinical diagnosis of brain death allows organ donation or withdrawal of support. Declaration of brain death follows a certain set of examinations. The code of practice throughout the world has not been systematically investigated. Brain death guidelines in adults in 80 countries were obtained through review of literature and legal standards and personal contacts with physicians. Legal standards on organ transplantation were present in 55 of 80 countries (69%). Practice guidelines for brain death for adults were present in 70 of 80 countries (88%). More than one physician was required to declare brain death in half of the practice guidelines. Countries with guidelines all specifically specified exclusion of confounders, irreversible coma, absent motor response, and absent brainstem reflexes. Apnea testing, using a PCO2 target, was recommended in 59% of the surveyed countries. Differences were also found in time of observation and required expertise of examining physicians. Additional provisions existed when brain death was due to anoxia. Confirmatory laboratory testing was mandatory in 28 of 70 practice guidelines (40%). There is uniform agreement on the neurologic examination with exception of the apnea test. However, this survey found other major differences in the procedures for diagnosing brain death in adults. Standardization should be considered.
Brain death (BD) is a by-product of the modern intensive care: since the report on coma depassé by Mollaret and Goulon in 19591 and the new criterion of death on neurological grounds published by the Harvard Medical School Ad Hoc Committee in 1968,2 both the definition and diagnostic of BD criteria have undergone a substantial evolution. Nowadays, most of the problems, dilemmas, and polemics raised in the past regarding the concept of BD, by terminological confusion, and by the grave responsibility of declaring dead a corpse with a still beating heart, are definitively overcome. However, despite the fact that BD is now widely accepted all over the world and regardless the certainty of its diagnosis when carefully formulated, its definition as well as diagnostic criteria are far from perfect and need further adjustments.
Calixto Machado
added a research item
As an American Academy of Neurology{AAN) Corresponding Fellow, I applaud the AAN position statement,1 because in recent years there were a number of controversies in suspected brain death (BO)cases.2 The Uniform Determination of Death Act referred to the term “accepted medical standards" but the lack of explicitness and institutional protocols variations have contributed to conflicting interpretations by the couts.1 Nevada became the first US state to revise these disagreements, stating that determination of death by neurologic criteria {DNC) must fulfill the AAN guidelines for BD in adults, and other guidelines for diagnosis in pediatric patients.3 Other debates in courts include whether apnea testing (AT) is a procedure with substantial risks demanding families’ informed consent. Nonetheless. the AT is a retentively simple and safe test when considering the precautions: preoxygenation and tracheal oxygen insufflation.4 In Cuba a legal basis is provided to protect physicians from being sued. The AT is a component of the BD determination protocol; therefore, it cannot be separated from the rest of clinical examination for a legal litigation. IInternet searches and advice/opinions from non-medical professionals can prompt erroneous interpretations of AT safety in patients’ relatives. BD determination must be a medical discussion, which should not require informed consent.
Calixto Machado
added a research item
Brain death (BD) is caused by a catastrophic injury leading to irreversible coma, absent brainstem reflexes and apnea. Recent publications of autopsy studies in brain-dead patients have concluded that due to organ transplant protocols, the time to brain fixation has been abbreviated and consequently, no distinguishing BD neuropathologic features can be described. Nonetheless, as autopsies allow the most complete description of the disease leading to BD, the objective of this paper is to describe the clinical and pathologic features in a series of 26 brain-dead patients, from a tertiary hospital of Havana, Cuba, from 2006 to 2008. We concluded that although in transplant era it is not possible to find any distinctive neuropathologic feature in BD. Autopsy studies remain the best method to confirm the direct cause of death, leading to an irreversible destruction of the brain. Hence, we recommend performing neuropathologic and clinical studies in brain-dead patients.
Calixto Machado
added 2 research items
Transplantation surgery started >50 years ago and has developed into an established medical practice in many countries. We consider it positive if our dead body could be used as an organ or tissue donor. If transplanted, our organs confer other human beings with a longer and better life. There is, however, a relative lack of organs compared with the needs, and many potential recipients die while on the waiting list for transplantation.
Calixto Machado
added a research item
Dear colleagues, We have the pleasure of holding the VIII International Symposium on Brain Death and Disorders of Consciousness, on December 4-7, 2018.This 4-day international conference covered a breadth of topics focused on current controversies and latest research findings in brain death and disorders of consciousness. Researchers, clinicians and basic scientists gathered for the conference in Havana, Cuba, the country’s largest city and our capital. Besides its tropical savanna climate, the city is also noted for its history, culture, architecture and monuments. Old Havana exhibits almost all the Western architectural styles seen in the New World, and its historic center was declared a UNESCO World Heritage Site in 1982. We look forward to informative lectures, debate on ongoing controversies and collegial networking. Calixto Machado, MD, PhD, FAAN President of the Symposium
Calixto Machado
added a research item
Lewis commented on the results of Machado et al., (2018) studying Jahi’s McMath's brain. Preservation of intracranial structures, both in the brainstem and cerebral hemispheres were documented nine months after a cardiac arrest. Conceptually, a brain-dead patient has a complete absence of intracranial cerebral blood flow. Hence, this contradicts a BD diagnosis in Jahi McMath's case. True EEG was found in this case over 2 μV of amplitude. Moreover, the power spectra analysis showed predominant activity within the delta-theta range. EEG may persist in posterior fossa catastrophes, not producing raised intracranial pressure. Jahi McMath presented a significant lesion at the pons, extending to the medulla. All heart rate variability (HRV) bands were preserved in this patient. BD has been characterized by the loss of all HRV components. This is a demonstration of autonomic activity conservancy in the medulla, within vagal, and other autonomic central nuclei. Another significant finding was the autonomic reactivity, assessed by HRV, to “Mother Talks” stimulation, demonstrating remaining function at different levels of the central autonomic system. These results might explain the video findings reported by Dr. Shewmon, who observed Jahi’s movements that he interpreted as responses to commands. Jahi displayed several clinical features of a BD state, but she was not braindead. She was not in coma, because her clinical examination showed a complete absence of brain-stem reflexes and no spontaneous driving to breath. She was not either in a vegetative state (VS), recently named as unresponsive wakefulness syndrome (UWS) or in a minimally conscious state, because she did not the presence of sleep-wake cycles and variably preserved cranial-nerve reflexes. Jahi was in a state of disorder of consciousness, not previously described. Considering the continuum of the consciousness spectrum, this state is placed between BD and Coma/VS/UWS. The authors accept that BD is a synonym for death and that in the great majority of cases, clinical examination is enough for BD determination, as affirmed by the American Academy of Neurology, and the Task Force for the Determination of Brain Death in Children. Jahi McMath is a rare case, resting in an uncommon state of consciousness. This might explain the controversies on her diagnosis. Actually, confirmatory tests are routinely used for the diagnosis of any disease. Ancillary tests will contribute to diminish pitfalls in the diagnosis of brain-dead cases. BD is the most challenging diagnosis for a physician. Why not to use a confirmatory test?
Calixto Machado
added a research item
Bernat defended the whole-brain concept of brain death (BD) and the US President's Commission recommended its adoption. Wijdicks stated, “the irreversible absence of functions of the brainstem is the necessary and sufficient component of brain death.” This view fully pertains to brainstem death, and not to the whole brain criterion. The American Academy of Neurology summit concluded that “BD is defined by irreversible loss of consciousness and brainstem function,” according the whole brain criterion. While there exists no perfect confirmatory test of death and as clinical evaluation may have pitfalls, ancillary tests should play a decisive role in helping to delineate concept of brain death.
Gerry Leisman
added a research item
“The irreversible absence of functions of the brainstem is the necessary and sufficient component of brain death.” This view fully pertains to brainstem death, and not to the whole brain criterion. The American Academy of Neurology summit concluded that ,“Brain death is defined by irreversible loss of consciousness and brainstem function,” according the whole brain criterion. As well-designed surveys have shown discrepancies with the AAN Guidelines on the use of ancillary tests. [1,5] Electrocardiogram (ECG) monitoring is routinely used by physicians to diagnose a cardiac arrest. While there is no perfect confirmatory test, ancillary tests should play a decisive role in helping to delineate the BD concept, as they have for outlining the cardio-respiratory view of death.
Calixto Machado
added 6 research items
In this paper we report on Public Health Resolution 90, which regulates the determination and certification of death in Cuba. Public Health Resolution 90 is of great social importance in our country since it allows the determination and certification of death to be lawfully regulated throughout the whole territory. It is the fruit of over ten years work by a national commission which was set up for that purpose. This resolution includes a series of features that are unprecedented on an international level. By legalising all the aspects linked with the determination and certification of death by means of a ministerial resolution (Ministry of Public Health), and not through a law passed by Parliament, no obstacles are created to prevent it from being reassessed and changed in the future in order to keep up with scientific and technical progress. Unlike most legislation throughout the world, this resolution does not regulate the determination of death, or brain death, linked with organ transplants. In fact, the word transplants does not appear anywhere in the resolution. The clinical and instrumental criteria for determining death were grouped under the heading of the well known true signs of death , but included a true sign based on the irreversible loss of brain functions . Although the irreversible absence of respiratory and circulatory functions, together with the presence of post mortem changes, were included as true signs, the national commission concluded that the death of an individual can only be defined in terms of the irreversible loss of brain functions . The clinical and instrumental criteria for determining death are included in two annexes to the resolution, which must be reviewed from time to time by the National Commission for the Determination of Death, as and when scientific and technical progress makes it necessary to do so. Among the instrumental tests used as a diagnostic aid for the irreversible loss of brain functions and, for perhaps the first time in the world, a battery of tests made up of multimodal evoked potentials and electroretinography has been included. Public Health Resolution 90 offers the legal framework for regulating the determination and certification of death in Cuba.
The medical authorities in England and Sweden should allow start of ventilation at respiratory arrest in patients with cerebral haemorrhage, an intracranial pressure higher systolic blood pressure and no cerebral blood flow. This procedure, called elective ventilation, which prepares for organ donation, was described 1990 in England. It was banned 1994 in England and 2007 in Sweden, based on the opinion that these patients are alive. If this is the case, is an open question. When resuscitation is not indicated, many patients may be declared legally dead at cardiac arrest, when cerebral blood flow stops, i.e. before brain damage is irreversible. In analogy with this “well-tried practise” also patients with no cerebral blood flow due to high intracranial pressure could be considered dead. Official statistics showed that 128deceased persons became donors during2009 in Sweden and 623 in England. If national rules were followed, ventilation and intensive care started, when it was believed that these patients could survive and recover. This assumption was wrong, which made it possible for them to become organ donors. It is a paradox that transplantation surgery should to such a degree rest on wrong estimates of the prognosis. Cuba had144 brain-dead donors 2009.In an unconscious patient with suspected brain damage the optimal treatment before computed tomography should include intubation to prevent aspiration pneumonia, ventilator treatment, capnography and pulse oxymetry, to prevent hypercapnia, hypoxia and hyperoxia. If this was clinical routine. the problems with elective ventilation would be avoided
Calixto Machado
added 2 research items
Although some decades have passed, there are still worldwide controversies about a concept of human death on neurological grounds. There are also disagreements on the diagnostic criteria for brain death, whether clinical alone or clinical plus ancillary tests. Moreover, some scholars who were strong defenders of a brain-based standard of death are now favoring a circulatory-respiratory standard. The study of coma is extremely important because lesions of the brain are responsible for quality of life in patients or cause of death. The main goal of Brain Death and Disorders of Consciousness is to provide a suitable scientific platform to discuss all topics related to human death and coma.
Gerry Leisman
added a research item
We compare and discuss three cases including: a clearly brain-dead patient, a vegetative state/unresponsive wakefulness syndrome (VS/UWS) patient and a patient diagnosed as brain-dead (BD) demonstrating some but not all clinical features of a BD state. Two of the patients demonstrated clear presentation allowing for an effective determination of state of death or consciousness. One patient, in comparison to the other two, presented with a complete absence of brainstem reflexes, absence of spontaneous driving to breath, and required permanent mechanical ventilation. Nonetheless, preservation of intracranial structures, remaining brain function in both brainstem and cerebral hemispheres was evidenced in the third case similar to the reported VS/UWS patient. Moreover, autonomic reactivity to mother's voice stimulation precluded the diagnosis of a BD in the latter case. This third patient was not comatose. The clinical examination demonstrated complete absence of brainstem reflexes, and no spontaneous driving to breath. This patient did not appear to be a VS/UWS, as she had not shown intermittent wakefulness with measurable sleep-wake cycles, and variably preserved cranial nerve reflexes. Therefore, the possibility of a responsive wakefulness state-minimally conscious state (MCS), or MCS emergence state was also excluded. This third patient in contradistinction to the other two demonstrates features similar to BD states, without being brain-dead, comatose, or VS/UWS or MCS states, and therefore rests somewhere on the spectrum of clinical consciousness. The importance of this paper is in that it highlights some of the difficulties in the clinical classification of states of consciousness, when the evaluation is categorized, showing that one of the patients presented rests somewhere else on the spectrum of clinical consciousness.
Gerry Leisman
added a research item
We compare and discuss three cases including: a clearly brain-dead patient, a vegetative state/unresponsive wakefulness syndrome (VS/UWS) patient and a patient diagnosed as brain-dead (BD) demonstrating some but not all clinical features of a BD state. Two of the patients demonstrated clear presentation allowing for an effective determination of state of death or consciousness. One patient, in comparison to the other two, presented with a complete absence of brainstem reflexes, absence of spontaneous driving to breath, and required permanent mechanical ventilation. Nonetheless, preservation of intracranial structures, remaining brain function in both brainstem and cerebral hemispheres was evidenced in the third case similar to the reported VS/UWS patient. Moreover, autonomic reactivity to mother's voice stimulation precluded the diagnosis of a BD in the latter case. This third patient was not comatose. The clinical examination demonstrated complete absence of brainstem reflexes, and no spontaneous driving to breath. This patient did not appear to be a VS/UWS, as she had not shown intermittent wakefulness with measurable sleep-wake cycles, and variably preserved cranial nerve reflexes. Therefore, the possibility of a responsive wakefulness state-minimally conscious state (MCS), or MCS emergence state was also excluded. This third patient in contradistinction to the other two demonstrates features similar to BD states, without being brain-dead, comatose, or VS/UWS or MCS states, and therefore rests somewhere on the spectrum of clinical consciousness. The importance of this paper is in that it highlights some of the difficulties in the clinical classification of states of consciousness, when the evaluation is categorized, showing that one of the patients presented rests somewhere else on the spectrum of clinical consciousness. Keywords: Brain death (BD); persistent vegetative state, unresponsive wakefulness syndrome (PVS/UWS), minimally conscious state (MCS), EEG, magnetic resonance imaging (MRI), autonomic nervous system (ANS), heart rate variability (HRV).
Calixto Machado
added 2 research items
To the Editor: The city of Havana, Cuba, welcomed colleagues from every continent for the First (1992), Second (1996), and Third (2000) International Symposia on Coma and Death. The U.S. Office of Foreign Assets Control decided to prohibit almost 100 American scholars from attending the fourth symposium, which was held March 9 through 12, 2004. Since 1992, internationally known American scholars have legally attended the symposia, held every four years: 25 attended in 1992, 31 in 1996, and 54 in 2000. Two important books have emerged from these conferences.1,2 When we invited our colleagues to attend the Fourth International . . .
Calixto Machado
added 18 research items
To the Editor: The American Academy of Neurology Therapeutics and Technology Assessment Subcommittee presented a remarkable report on the transcranial Doppler ultrasonography (TCD) applications for clinical use.1 The use of TCD to diagnose cerebral circulatory arrest and brain death (BD) is of interest. Bernat2 recently discussed that irreversibility has been a prerequisite for BD confirmation in every set of BD diagnostic criteria, arguing that “the only reliable proof of irreversibility is demonstrating the complete absence of intracranial circulation.” An advantage of TCD that the Subcommittee emphasized, TCD “can be performed at the bedside and repeated as needed or applied for continuous monitoring,” make this technique applicable to the intensive care environment to comatose, intubated, and unresponsive patients. A major limitation is that “it can demonstrate cerebral blood flow velocities only in certain segments of large intracranial vessels,” does not decrease its potentiality to access an intracranial circulatory arrest.1 Several other techniques have also shown to be useful, but contrary to TCD, it is almost always mandatory to move patients outside the ICU.1,3 The subcommittee compared TCD sensitivity and specificity in different clinical settings. It is notable that the highest percentages corresponded to TCD for detecting circulatory arrest (91 to 100% and 97 to 100%).1 Although there is no perfect ancillary test in clinical practice,3 these values are very high. We recently passed a law for the determination and certification of death in Cuba.4 We proposed using confirmatory tests (still optional): to prove absent cerebral flow; to demonstrate loss of bioelectric activity; when clinical examination is not reliable; to shorten period of observation; and in primary brainstem lesions. Among those tests to detect absent cerebral blood flow, we defend the use of TCD because of the outlined advantages.1 We concluded that by combining TCD and neurophysiologic tests (multimodality evoked potentials and electroretinography), BD diagnostic reliability could be considerably increased.4,5 References 1. Sloan MA, Alexandrov AV, Tegeler AH, et al. Assessment: Transcranial Doppler ultrasonography: Report of the Therapeutics and Technology Assessment Subcommittee of the American Academy of Neurology. Neurology, 2004;62:1468–1481. 2. Bernat 1- Bernat J. On irreversibility as a prerequisite for brain death determination. In: Machado C, Shewmon DA, eds. Brain death and disorders of consciousness. New York: Kluwer Academic/Plenum Publishers, 2004: 161–168. 3- Cabrera C, Domınguez-Roldan JM, Manyalich M, et al. Persistence of intracranial diastolic flow in transcranial Doppler sonography exploration of patients in brain death. Transplant Proc 2003;35:1642–1643. 4- Machado C, Abeledo M, Alvarez C, et al. Cuba has passed a law for the determination and certification of death. In: Machado C, Shewmon DA, eds. Brain death and disorders of consciousness. New York: Kluwer Academic/Plenum Publishers, 2004:139–142. 5. Machado C. Evoked potentials in brain death. Clin Neurophysiol 2004; 115:238–239. Calixto Machado, MD, PhD, Havana, Cuba
‘Physicians are the only professionals authorized to diagnose and certify death according to a norm established by the Ministry of Public Health’ (5). According to the Cuban Parliament, a resolution is a law that legalizes a working standard within any Ministry and that can be signed and changed by the Minister in function (4, 5). Hence, our lawyers left to physicians the responsibility of presenting norms related to human death. Therefore, the Ministry of Public Health needed to respond to the present Civil Code (5) by writing a resolution on this subject. As the Civil Code did not require a definition, the Commission followed this norm and presented not a concept, but ways to diagnose death. Hence, the Commission enumerated three possible situations for diagnosing death (3, 4): 1) Outside the intensive care environment (without life support) physicians apply the cardio-circulatory and respiratory criteria. 2) In forensic medicine circumstances physicians utilize cadaveric signs. (They do not even need a stethoscope.) 3) In the intensive care environment (with life support) when cardio-circulatory and/or respiratory arrest occurs physicians utilize the cardio-circulatory and respiratory criteria. When physicians suspect an irreversible loss of brain functions in a heart-beating and ventilatory supported case, BD diagnostic criteria are applied. The diagnosis of death was based on the finding of any of the Signs of Death: I Irreversible loss of respiratory function. II Irreversible loss of cardio-circulatory functions. III Algor mortis (postmortem coldness). IV Livor mortis (postmortem lividity). V Rigor mortis (postmortem rigidity). VI Cadaveric spasm. VII Loss of muscle contractions. VIII Putrefaction. IX Irreversible loss of brain functions. Signs I and II correspond to the classical respiratory and cardio-circulatory functions. Signs III to VIII are related to forensic circumstances. Sign IX corresponds to the BD diagnosis. This method of diagnosing death, based on finding any of the signs of death, was not related to the concept that there are different types of death. The irreversible loss of cardio-circulatory and respiratory functions can only cause death when ischemia and anoxia are prolonged enough to produce an irreversible destruction of the brain. According to the Commission there is only one kind of death, based on the irreversible loss of brain functions (3—10). This Cuban law did not even mention the term ‘transplants’. It is clear the human beings die regardless bodies would be useful or not for transplantation (3, 4). C. Machado
Calixto Machado
added 2 research items
On 5 August 1968, publication of the Harvard Committee's report on the subject of "irreversible coma" established a standard for diagnosing death on neurological grounds. On the same day, the 22nd World Medical Assembly met in Sydney, Australia, and announced the Declaration of Sydney, a pronouncement on death, which is less often quoted because it was overshadowed by the impact of the Harvard Report. To put those events into present-day perspective, the authors reviewed all papers published on this subject and the World Medical Association web page and documents, and corresponded with Dr A G Romualdez, the son of Dr A Z Romualdez. There was vast neurological expertise among some of the Harvard Committee members, leading to a comprehensible and practical clinical description of the brain death syndrome and the way to diagnose it. This landmark account had a global medical and social impact on the issue of human death, which simultaneously lessened reception of the Declaration of Sydney. Nonetheless, the Declaration of Sydney faced the main conceptual and philosophical issues on human death in a bold and forthright manner. This statement differentiated the meaning of death at the cellular and tissue levels from the death of the person. This was a pioneering view on the discussion of human death, published as early as in 1968, that should be recognised by current and future generations.
Calixto Machado
added 2 research items
Falso negativo con doppler transcraneal en el diagnóstico de la muerte encefálica. Presentación de caso Negative false with transcranial doppler in the brain death diagnosis. Case report ___________________________________________________________________ Resumen Introducción: el doppler transcraneal (DTC) es utilizado frecuentemente en el diagnóstico de la muerte encefálica (ME). El uso de esta técnica presenta algunas limitaciones, encontrándose en ocasiones casos falsos negativos. Métodos: se estudia paciente con trauma cráneoencefálico (TCE) severo y he-matoma subdural temporoparietal por pérdida brusca de conciencia en el cur-so de una hemorragia intraparenquima-tosa putaminal. Se realiza intervención quirúrgica, con craneotomía realizada en hemisferio izquierdo, a pesar de lo cual presenta una mala evolución. Es diagnosticado en ME realizándose dos evaluaciones clínicas positivas para la misma, con intervalo de 6 horas de separación. Luego de concluida cada evaluación se realizó DTC, explorando las arterias cerebrales del polígono de Willis; con un tercer DTC realizado seis ________________________________ Correspondencia: Alexeis Planas Oñate. UCI polivalente. Hospital Universitario "General Ca-lixto García". La Habana. Email: alexeipo@infomed.sld.cu _______________________________________ horas después de la segunda evaluación clínica. Resultados: el DTC mostró patrones de parada circulatoria cerebral en la arteria cerebral media (ACM) derecha y en la arteria basilar mantenidos en el tiempo; mientras que en la ACM izquierda correspondiente al lado de la craneotomía, persistían las velocidades de flujo sanguíneo cerebral, situación que se mantuvo con el decursar del tiempo. Conclusiones: paciente con diagnós-tico clínico de ME, con DTC que mostró persistencia de velocidades de flujo sanguíneo en la ACM del hemisferio de la craneotomía realizada, a pesar de presentar parada circulatoria cerebral por DTC por más de 18 horas, en la ACM derecha y arteria basilar, demos-trándose la limitación del DTC en el diagnóstico de la ME en las grandes craneotomías.
Calixto Machado
added 5 research items
Background: In accordance with the Uniform Determination of Death Act, guidelines for brain death determination are developed at an institutional level, potentially leading to variability of practice. We evaluated the differences in brain death guidelines in major US hospitals with a strong presence of neurology and neurosurgery to determine whether there was evidence of variation from the guidelines as put forth by the American Academy of Neurology (AAN). Methods: We requested the guidelines for determination of death by brain criteria from the US News and World Report top 50 neurology/neurosurgery institutions in 2006. We evaluated the guidelines for five categories of data: guideline performance, preclinical testing, clinical examina- tion, apnea testing, and ancillary tests. We compared the guidelines directly with the AAN guide- lines for consistencies/differences. Results: There was an 82% response rate to requests. Major discrepancies were present among institutions for all five categories. Variability existed in the guidelines' requirements for perfor- mance of the evaluation, prerequisites prior to testing, specifics of the brainstem examination and apnea testing, and what types of ancillary tests could be performed, including what pitfalls or limitations might exist. Conclusions: Major differences exist in brain death guidelines among the leading neurologic hos- pitals in the Unites States. Adherence to the American Academy of Neurology guidelines is vari- able. If the guidelines reflect actual practice at each institution, there are substantial differences in practice which may have consequences for the determination of death and initiation of trans- plant procedures. Neurology® 2008;70:284-289
Brain death (BD) diagnosis should be established based on the following set of principles, i.e. excluding major confusing factors, identifying the cause of coma, determining irreversibility, and precisely testing brainstem reflexes at all levels of the brainstem. Nonetheless, most criteria for BD diagnosis do not mention that this is not the only way of diagnosing death. The Cuban Commission for the Determination of Death has emphasized the aforesaid three possible situations for diagnosing death: a) outside intensive care environment (without life support) physicians apply the cardio-circulatory and respiratory criteria; b) in forensic medicine circumstances, physicians utilize cadaveric signs (they do not even need a stethoscope); c) in the intensive care environment (with life support) when cardiorespiratory arrest occurs physicians utilize the cardio-circulatory and respiratory criteria. This methodology of diagnosing death, based on finding any of the death signs, is not related to the concept that there are different types of death. The irreversible loss of cardio-circulatory and respiratory functions can only cause death when ischemia and anoxia are prolonged enough to produce an irreversible destruction of the brain. The sign of irreversible loss of brain functions, that is to say BD diagnosis, is fully reviewed.
Calixto Machado
added 2 research items
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