Brain death (first of two parts)

Pediatric heart transplantation: Looking forward after five decades of learning

Heart transplantation has become the standard of care for pediatric patients with end-stage heart disease throughout the world. Since the first transplant was performed in 1967, the number of transplants has grown dramatically with 13 449 pediatric heart transplants being reported to The International Society of Heart and Lung Transplant (ISHLT) between January 1992 and June 30, 2018. Outcomes have consistently improved over the last few decades, specifically short-term outcomes. Most recent survival data demonstrate that recipients who survive to 1-year post-transplant have excellent long-term survival with more than 60% of those who were transplanted as infants being alive 25 years later. Nonetheless, the rates of graft loss beyond the first year have remained relatively constant over time; driven primarily by our poor understanding and lack of treatments for chronic allograft vasculopathy (CAV). Acute rejection, CAV, graft failure, and infection continue to be the major causes of death within the first 5 years post-transplant. In addition, renal dysfunction, malignancy, and the need for re-transplantation remain as significant issues that require close follow-up. Looking forward, key challenges include improving donor utilization rates (including donation after cardiac death (DCD) and the use of ex vivo perfusion devices), the development of non-invasive biomarkers for rejection, efforts to mitigate the long-term effects of immunosuppression, and prevention of CAV. It is not possible to cover the entire evolution of pediatric heart transplantation over the last five decades, but in this review, we hope to touch on key observations, lessons learned, and practice changes that have advanced the field, as well as glance ahead to the next decade.

Diagnostic Value of Computed Tomography Angiography in Confirmation of Brain Death

BACKGROUND

Accurate and on-time confirmation of brain death (BD) is necessary to prevent unnecessary treatment and allow for well-timed organ harvest for transplantation. Although the clinical criteria for BD are legally reliable in some countries, others might prefer complementary ancillary tests to assess the brain's electrical activity and/or blood circulation. The present study aims to define the sensitivity and specificity of computed tomography angiography using 4-, 7-, and 10-point tests compared with the clinical criteria and electroencephalographic findings in patients with BD.

METHODS

A total of 32 patients with a confirmed diagnosis of BD according to their clinical criteria (cases) and 18 patients with a Glasgow coma scale score of 3 and absent brain stem and papillary reflexes who had spontaneous respiration (controls) were included in the present study. All the patients had blood pressure >90 mm Hg, diuresis >100 mL/hour, and central venous pressure >6-8 mm Hg, and undergone computed tomography angiography (CTA). The 4-, 6-, and 10-point criteria were used to determine the opacity and lack of opacity of the brain vessels in the CTA evaluation scales for the diagnosis of BD.

RESULTS

The 2 groups were homogeneous in terms of age, gender distribution, and coma etiology. All 18 patients in the control group received a score of 0 in the 4-, 7-, and 10-point scores. In contrast, the average values for the 4-, 7-, and 10-point scores for the patients with confirmed BD were 3.75 ± 0.67, 6.4 ± 1.36, and 9.06 ± 2.2, respectively. Of the patients with BD, 28 (87.5%), 26 (81.25%), and 25 (78.12%) received the full score for the 4-point, 7-point, and 10-point tests. The sensitivity, specificity, and negative and positive predictive values for all 3 scores were 100%. Also, the sensitivity for the various cerebral vessels were as follows: internal cerebral vein, 100%; great cerebral vein, 96.9%; posterior 2, 90.6%, middle 4, 87.5%; basilar artery, 84.4%; and anterior 3, 84.4%. Finally, the specificity for the lack of opacification in all these vessels for the diagnosis of BD was 100%.

CONCLUSIONS

According to our findings, the CTA-based 4-point scoring system with 100% specificity can be used with the clinical examination findings to confirm BD.

Analytic Reviews : The Diagnosis of Brain Death in the Adult Patient

The biological tenet upon which brain death is founded is absolute. The brain's inability to undergo cellular divi sion ensures that once individual neurons die they can not be replaced. Extrapolating this to the total brain, once the entire brain is dead no recovery can occur, and the patient's family can be guaranteed of that fact. The clinician, therefore, is faced primarily with a diagnostic challenge in determining that brain death is indeed pres ent. The components, procedures, and limitations of that diagnostic process in the adult patient are the sub jects of this discussion.

Cardiac Dysrhythmias during Donor Care

Organ procurement coordinators must treat various cardiac dysrhythmias (arrhythmias), including rhythm disturbances that may cause or follow a cardiac arrest, in about 15% to 50% of donors. Treatment decisions should be based on the particular dysrhythmia and its effect on donor blood pressure. Medications selected should be effective but short acting. In this article, data available in publications located through a PubMed search are reviewed and specific dysrhythmias that are likely to occur during donor care are described. Treatment recommendations are based on guidelines from the American Heart Association.

History of brain death as death: 1968 to the present

The concept of brain death was formulated in 1968 in the landmark report A Definition of Irreversible Coma. While brain death has been widely accepted as a determination of death throughout the world, many of the controversies that surround it have not been settled. Some may be rooted in a misconstruction about the history of brain death. The concept evolved as a result of the convergence of several parallel developments in the second half of the 20th century including advances in resuscitation and critical care, research into the underlying physiology of consciousness, and growing concerns about technology, medical futility, and the ethics of end of life care. Organ transplantation also developed in parallel, and though it clearly benefited from a new definition of death, it was not a principal driving force in its creation. Since 1968, the concept of brain death has been extensively analyzed, debated, and reworked. Still there remains much misunderstanding and confusion, especially in the general public. In this comprehensive review, I will trace the evolution of the definition of brain death as death from 1968 to the present, providing background, history and context.

Brain death

The diagnosis of brain death should be based on a simple premise. If every possible confounder has been excluded and all possible treatments have been tried or considered, irreversible loss of brain function is clinically recognized as the absence of brainstem reflexes, verified apnea, loss of vascular tone, invariant heart rate, and, eventually, cardiac standstill. This condition cannot be reversed - not even partly - by medical or surgical intervention, and thus is final. Many countries in the world have introduced laws that acknowledge that a patient can be declared brain-dead by neurologic standards. The U.S. law differs substantially from all other brain death legislation in the world because the U.S. law does not spell out details of the neurologic examination. Evidence-based practice guidelines serve as a standard. In this chapter, I discuss the history of development of the criteria, the current clinical examination, and some of the ethical and legal issues that have emerged. Generally, the concept of brain death has been accepted by all major religions. But patients' families may have different ideas and are mostly influenced by cultural attitudes, traditional customs, and personal beliefs. Suggestions are offered to support these families.

The definition and criterion of death

The definition and criterion of death have been rendered ambiguous by developments in organ support technology, particularly the positive-pressure ventilator and vasopressor medications, that uncouple the unitary loss of vital functions in death and create cases in which the brain has been destroyed while circulation and ventilation can be supported. Developing a biophilosophic analysis of the meaning of death before physicians can declare it requires four sequential steps: (1) agreement on the paradigm conditions that frame the analysis and clarify the task; (2) identifying the definition of death, which makes explicit the meaning of death that is accepted in our consensual usage of the term but that has become obscured by technology; (3) identifying the criterion of death that shows that the definition has been fulfilled, and that can be incorporated into a death statute; and (4) devising bedside tests of death for physicians to perform to satisfy the criterion. Although there is a strong consensus on death determination medical standards in countries around the world that has been enshrined into laws, and accepted by most societies and religions, there remains an active dispute among scholars on the precise definition and criterion of death.

The transatlantic divide over brain death determination and the debate

In 1976, the Royal College of Physicians published neurological criteria of death. The memorandum stated that-after preconditions and exclusion criteria were met-the absence of brainstem function, including apnoea testing, would suffice. In the USA, many experts felt that brain death could be only determined by demonstrating death of the entire brain. In the history of further refinement of UK and USA brain death criteria, one particular period stands out that would bring about an apparent transatlantic divide. On 13 October 1980, the British Broadcasting Corporation aired a programme entitled 'Transplants: Are the Donors Really Dead?' Several United States experts not only disagreed with the United Kingdom criteria, but claimed that patients diagnosed with brain death using United Kingdom criteria could recover. The fallout of this television programme was substantial, as indicated by a media frenzy and a 6-month period of heated correspondence within The Lancet and The British Medical Journal. Members of the Parliament questioned the potential long-term effect on the public's trust in organ transplantation. Given the concerns raised, the British Broadcasting Corporation commissioned a second programme, which was broadcast on 19 February 1981 entitled 'A Question of Life or Death: The Brain Death Debate.' Two panels debated the issues on the accuracy of the electroencephalogram and its place, the absolute need for assessing preconditions before an examination, the problems with recognition of toxins and the feasibility of doing a new prospective study in the United Kingdom, which would follow patients' examination assessed with United Kingdom criteria until cardiac standstill. The positions of the United States and United Kingdom remained diametrically opposed to each other. This article revisits this landmark moment and places it in a wider historical context. In the USA, the focus was not on the brainstem, and the definition of brain death became rapidly infused with terms such as whole brain death (all intracranial structures above the foramen magnum), cerebral death (all supratentorial structures) or higher brain death (cortical structures) virtually synonymous with persistent vegetative state. This review also identifies the fortitude of neurosurgeon Bryan Jennett and neurologist Christopher Pallis by introducing new corroborative data on the diagnosis of brain death and clarifying the United Kingdom position. Both understood that brainstem death was the infratentorial consequence of a supratentorial catastrophe. With the 1995 American Academy of Neurology practice parameters, the differences between the UK and USA brain death determination would become much less apparent.

[Machines and arguments: from life support technologies to the definition of brain death]

The article analyzes academic production about the debate surrounding the definition of brain death, based on bibliographic and documental research of international medical periodicals in the 1960s. The development and adoption of life support technologies during the twentieth century sparked a heated debate that sought to legitimize new procedures like organ transplants. As its practices changed, medical science set about inventing new knowledge about these practices. Discussions as to the definition of brain death turned it into a 'black box', dismantled by anthropological studies into the topic starting in 1980s. The present article explores the deconstruction of brain death as a black box.

A survey to determine the understanding of the conceptual basis and diagnostic tests used for brain death by neurosurgeons in Canada

OBJECTIVE

To determine the understanding of the conceptual basis and diagnostic tests used for brain death (BD) by neurosurgeons in Canada.

METHODS

Between February and June 2006, a previously developed survey was mailed to every neurosurgeon in Canada.

RESULTS

Of 223 surveys mailed, 147 (66%) were returned; of these, 128 (87%) were completed and analyzed. When asked to choose a conceptual reason to explain why BD is equivalent to death, 50 (39%) chose a higher brain concept, 50 (39%) chose a prognosis concept, and 33 (26%) chose a loss of integration of the organism concept. More than half of respondents answered that BD is not compatible with electroencephalographic activity or brainstem evoked potential activity. More than one-third of respondents answered that some cerebral blood flow or a brainstem with minimal microscopic damage was not compatible with BD. Of the 90 respondents who answered that they were comfortable diagnosing BD because the conceptual basis of BD makes it equivalent to death of the patient, in their own words, 14 (16%) used a loss of integration concept, 20 (22%) used a prognosis concept, 25 (28%) used a higher brain concept, and 39 (43%) did not articulate a concept. When asked, "Are brain death and cardiac death the same state (i.e., are both death of the patient)?," 57 (45%) answered "No."

CONCLUSION

Within the neurosurgical community, a stand-alone concept of BD does not exist. There is also significant variability in the understanding of the tests that are compatible with the criterion of BD.

Maternal brain death--an Irish perspective

BACKGROUND

Brainstem death is a concept used in cases in which life-support equipment obscures the conventional cardiopulmonary criteria of death. Brainstem death during pregnancy is an occasional and tragic occurrence.

AIMS

To considerthe ethical, legal and medical issues raised by maternal brainstem death.

METHODS

Medline and Embase search.

RESULTS

The death of the mother mandates consideration of whether continuing maternal organ supportive measures in an attempt to attain foetal viability is appropriate, or whether it constitutes futile care. There is no theoretical limit to the duration of time for which maternal somatic function may be sustained. However, successful prolongation of maternal somatic function in pregnancies of less than 16 weeks gestation has not been reported to date. There is no legal imperative to continue maternal somatic support where there is little likelihood of a successful foetal outcome.

CONCLUSION

The difficult issues raised by maternal brainstem death mandates a consensus building approach to decision making in this context.

Maternal brain death and somatic support

Brain death is a concept used in situations in which life-support equipment obscures the conventional cardiopulmonary criteria of death, and it is legally recognized in most countries worldwide. Brain death during pregnancy is an occasional and tragic occurrence. The mother and fetus are two distinct organisms, and the death of the mother mandates consideration of the well-being of the fetus. Where maternal brain death occurs after the onset of fetal viability, the benefits of prolonging the pregnancy to allow further fetal maturation must be weighed against the risks of continued time in utero, and preparations must be made to facilitate urgent cesarean section and fetal resuscitation at short notice. Where the fetus is nonviable, one must consider whether continuation of maternal organ supportive measures in an attempt to attain fetal viability is appropriate, or whether it constitutes futile care. Although the gestational age of the fetus is central to resolving this issue, there is no clear upper physiological limit to the prolongation of somatic function after brain death. Furthermore, medical experience regarding prolonged somatic support is limited and can be considered experimental therapy. This article explores these issues by considering the concept of brain death and how it relates to somatic death. The current limits of fetal viability are then discussed. The complex ethical issues and the important variations in the legal context worldwide are considered. Finally, the likelihood of successfully sustaining maternal somatic function for prolonged periods and the medical and obstetric issues that are likely to arise are examined.

Brain tissue oxygenation in brain death

INTRODUCTION

The value of brain tissue oxygenation (PbtO2) measurements in determining brain death is unknown.

METHODS

Eleven of 72 patients who had brain tissue oxygen monitors placed experienced brain death. Admission diagnoses included six severe traumatic brain injuries, one multiple trauma with cardiac arrest, one brain tumor, one subarachnoid hemorrhage, one intracerebral hemorrhage, and one cerebral stroke. Eleven males and zero females were studied, with an average age of 26 years (range: 20-70 years). Nine patients had Glasgow Coma Scores (GCS) of 3 on admission, one patient had a GCS of 5, and one patient had a GCS of 15.

RESULTS

Time from admission to declaration of brain death varied from 5 hours to 7 days; the most common interval was 1 or 2 days. Cerebral perfusion pressure (CPP) fell to 0 in eight patients, which indicated primary failure of cerebral perfusion. CPP stayed above 60 mmHg in three patients, indicating primary tissue failure, possibly of the cerebral microvasculature. PbtO2 fell to 0 in all patients who experienced brain death, and all patients with PbtO2 of 0 experienced brain death. None of the 61 patients who did not experience brain death had confirmed PbtO2 readings of 0.

CONCLUSION

PbtO2 can be successfully and accurately used as a bedside adjunctive test for brain death. The use of PbtO2 as a sole confirmatory test for brain death in the setting of an appropriate clinical examination will require the evaluation of a larger number of patients to assess its sensitivity and specificity.

Pregnancy in a persistent vegetative state: case report, comparison to brain death, and review of the literature

Severe maternal neurologic injury during pregnancy has the potential for fetal demise without advanced critical care support to the mother. Brain death is the unequivocal and irreversible loss of total brain function, whereas patients in a vegetative state, by contrast, have preserved brain stem function but lack cerebral function. They can appear to be awake, have sleep-wake cycles, be capable of swallowing, and have normal respiratory control, but there are no purposeful interactions. These conditions have different maternal prognoses, but both have resulted in near-normal neonatal outcomes with long latencies from maternal injury to delivery in previously published cases. This article compares and contrasts the 11 cases of brain death with 15 cases of persistent vegetative state in pregnancy. We found that the mean latency between maternal brain injury and delivery was significantly shorter in the brain-dead patients as compared with those in a vegetative state (46 days vs. 124 days, P </=.001). Correspondingly, the gestational ages at delivery (29.7 weeks vs. 33.2 weeks, P </=.01) and the birth weights (1380 g vs. 2145 g, P </=.01) were shorter in duration and smaller in size in the brain-dead group. We also present a case of persistent vegetative state in pregnancy at our institution with both maternal and neonatal death in the context of previously published literature with a focus on obstetric and ethical management. We hope this information will help elucidate the issues for providers confronted with these unique and challenging cases.

TARGET AUDIENCE

Obstetricians & Gynecologists, Family Physicians.

LEARNING OBJECTIVES

After completion of this article, the reader should be able to state the difference between coma, persistent vegetative state and brain death, to describe the neurologic aspects of a patient in a persistent vegetative state, and to list the fetal effects of maternal brain injury.

Role of brain death and the dead-donor rule in the ethics of organ transplantation

The "dead-donor rule" requires patients to be declared dead before the removal of life-sustaining organs for transplantation. The concept of brain death was developed, in part, to allow patients with devastating neurologic injury to be declared dead before the occurrence of cardiopulmonary arrest. Brain death is essential to current practices of organ retrieval because it legitimates organ removal from bodies that continue to have circulation and respiration, thereby avoiding ischemic injury to the organs. The concept of brain death has long been recognized, however, to be plagued with serious inconsistencies and contradictions. Indeed, the concept fails to correspond to any coherent biological or philosophical understanding of death. We review the evidence and arguments that expose these problems and present an alternative ethical framework to guide the procurement of transplantable organs. This alternative is based not on brain death and the dead-donor rule, but on the ethical principles of nonmaleficence (the duty not to harm, or primum non nocere) and respect for persons. We propose that individuals who desire to donate their organs and who are either neurologically devastated or imminently dying should be allowed to donate their organs, without first being declared dead. Advantages of this approach are that (unlike the dead-donor rule) it focuses on the most salient ethical issues at stake, and (unlike the concept of brain death) it avoids conceptual confusion and inconsistencies. Finally, we point out parallel developments, both domestically and abroad, that reflect both implicit and explicit support for our proposal.

Neocortical versus whole-brain conceptions of personal death

Robert Veatch argues that the death of a person should be equated with the irreversible destruction of the cerebral cortex. This position is here questioned on grounds of tutiorism as well as on the basis of its philosophical assumptions. It is agrued that whole-brain death as an account of personal death is not open to these objections, and is a conception that can satisfy tutiorist standards of safety. The role of the EEG as an indicator of death is discussed.

Irreversible maternal brain injury during pregnancy: a case report and review of the literature

Maternal brain death or massive injury leading to persistent vegetative state during pregnancy is a rare event. Since 1979, 11 cases, including the current one, of irreversible maternal brain damage in pregnancy have been reported. In all but one, the pregnancies were prolonged with a goal of achieving delivery of a viable infant. Current advances in medicine and critical care enable today's physician to offer prolonged life-support to maximize the chances for survival in the neonate whose mother is technically brain dead. We present a case at our institution and review all previously published cases in the English literature for comparison as well as make management recommendations.

Tc-99m hexamethylpropylene amine oxime scintigraphy in the diagnosis of brain death and its implications for the harvesting of organs used for transplantation

PURPOSE

Diagnosing brain death is important in managing the comatose patient for whom the continuation of life support is being questioned and when organ harvesting is being considered. The virtual immediate localization of Tc-99m HMPAO to cerebral and cerebellar tissue provides an index of blood perfusion, and its absence denotes brain death. Other methods for assessing brain death include cerebral angiography, MRI, CT imaging after inhalation of stable xenon, electroencephalography, and clinical examination. The contrast material used for angiography may damage harvested organs, and the other studies have significant errors. MRI, CT imaging, and angiography are unsuitable for bedside use.

METHODS

Twenty-three patients, who presented with head trauma, prolonged anoxia or intrinsic brain disease (e.g., glioblastoma multiforme) and who were brain-dead by clinical examination criteria, were referred to the nuclear medicine division for verification of brain death. For adults, approximately 25 mCi Tc-99m hexamethylpropylene amineoxime (HMPAO) was administered intravenously. All patients but one were imaged using a mobile scintillation camera at the bedside.

RESULTS

We demonstrated (1) both cerebral and cerebellar perfusion, (2) neither cerebral nor cerebellar perfusion, (3) cerebral without cerebellar perfusion, and (4) cerebellar without cerebral perfusion. Patients without cerebral perfusion were diagnosed as brain-dead. The significance of a viable cerebellum in the absence of cerebral viability was not fully appreciated, although organs were harvested from such patients. We determined how well the clinical examination criteria held up in the diagnosis of brain death against the new gold standard of Tc-99m HMPAO scintigraphy: Clinical examination criteria correctly predicted brain death only 83% of the time compared with HMPAO scintigraphy.

CONCLUSIONS

Brain death assessment by Tc-99m HM-PAO scintigraphy has proved to be a reliable, safe, and cost-effective bedside method and may have practical application in the assessment of brain death in potential cadaveric donors.

99mTc HM-PAO brain perfusion SPECT in brain death

Diagnosis of brain death must be certain to allow discontinuation of artificial ventilation and organ transplantation. Brain death is present when all functions of the brain stem have irreversibly ceased. Clinical and electrophysiological criteria may be misinterpreted due to drug intoxication, hypothermia or technical artefacts. Thus, if clinical assessment is suboptimal, reliable early confirmatory tests may be required for demonstrating absence of intracranial blood flow. We have easily carried out and interpreted 99mTc HM-PAO SPECT in a consecutive series of 40 comatose patients with brain damage, without discontinuing therapy. Brain death was diagnosed in 7 patients, by recognising absence of brain perfusion, as shown by no intracranial radionuclide uptake. In patients in whom perfusion was seen on brain scans, HM-PAO SPECT improved assessment of the extent of injury, which in general was larger than suggested by CT.

The physiological changes associated with brain death--current concepts and implications for treatment of the brain dead organ donor

The profound physiological disturbances associated with severe intracerebral pathology have long been recognized. These changes have also been described in the brain dead potential organ donor but have only been studied since the early 1980s. Physiological disturbances in the brain dead organ donor result in a diffuse vascular regulatory injury and a diffuse metabolic cellular injury. The net result of these changes is an inexorable deterioration of all organs and eventual "cardiovascular death" of the patient. This paper reviews these physiological changes and the effect they may have on solid transplantable tissues, and discusses the management of brain dead organ donor with regard to these changes. Current concepts of brain death and how they may affect the interpretation of the observed physiological changes are also reviewed.

Prognosis of deeply comatose patients on ventilators

Although the concept of brain death has been widely accepted, the criteria required for making the diagnosis remain controversial. This prospective study was undertaken to examine the reliability of a set of clinical criteria adopted in Taiwan. One hundred and forty deeply comatose patients (101 men, 39 women; mean age 49.5 (SD 17.6) years) requiring ventilation were studied. Seventy three patients met the clinical criteria for brainstem death; all developed cardiac asystole (97% within seven days) despite continued full cardiorespiratory support. Brainstem death was diagnosed in only two of the 21 patients with hypoxic or ischaemic insults. This stresses the rarity of hypoxic or ischaemic encephalopathy as a cause of brainstem death. The results show that if strict attention is paid to preconditions and exclusions, brainstem death can be reliably diagnosed on clinical grounds alone.

Brain death: determination with brain stem evoked potentials and radionuclide isotope studies

Thirty-three patients fulfilling the clinical criteria for brain death were tested by Brainstem Auditory Evoked Potentials (BAEP) and Radionuclide Cerebral Angiography and Brain Perfusion Studies. There was a significant correlation between the BAEP and radionuclide study outcomes. All patients with absence of BAEP showed no cerebral perfusion. These findings, added to the clinical findings, resulted in a final diagnosis of brain death in all patients. It is concluded that BAEP and Radionuclide Cerebral Perfusion studies are useful adjuncts for proving that brain death has really occurred.

The effects of the falling therapeutic and subtherapeutic barbiturate blood levels on electrocerebral silence in clinically brain-dead children

In a retrospective study at a large children's hospital, we identified 92 children who had received barbiturates that were simultaneously discontinued at the time they were being evaluated for brain death in the presence of electrocerebral silence and clinical brain death by physical exam. Of these 92 children, 67 had barbiturate levels that were monitored from initial therapeutic or subtherapeutic levels. Repeat EEGs were obtained in 76 patients, and in all electrocerebral silence and clinical brain death (by exam) persisted despite the lower barbiturate levels. The study suggests that therapeutic and subtherapeutic barbiturate levels have no effect on the outcome of children who fulfill the criteria for brain death.

Anaesthetic management of the brain dead for organ donation

An increasing number of anaesthetists is being called upon to manage organ donors during organ retrieval procedures. We briefly describe the technical aspects of the surgical procedure together with a guide to the anaesthetic management. The aims of the latter may be summarized as the "Rule of 100": systolic blood pressure greater than 100 mmHg, urine output greater than 100 ml.hr-1, PaO2 greater than 100 mmHg, haemoglobin concentration greater than 100 g.L-1. Common management problems (hypotension, arrhythmias, diabetes insipidus, oliguria, and coagulopathy) are discussed in detail. The intraoperative management of the brain-dead organ donor provides the anaesthetist with the challenge of a major surgical procedure in a subject with important physiological derangements.

Serum vasopressin (AVP) levels in polyuric brain-dead organ donors

Hydromineral metabolism and serum arginine-vasopressin (AVP) levels were investigated in 11 patients who sustained brain death. They showed various degrees of polyuria with low osmolality and low fractional sodium excretion. Urine osmolality was always below that of serum, and AVP levels were between 1.3 and 50.0 pg/ml vs 0.7-8.0 pg/ml in ten normal subjects. Thus central diabetes insipidus was excluded. A renal mechanism inducing water diuresis has to be assumed. The type of renal lesion, however, remains unclear.

Ethical decisions in the history of organ transplantation

Images

Perimortem cesarean section

Perimortem cesarean section probably represents an underemphasized procedure on the skills list of the emergency physician. Although fraught with emotional and medicolegal overtones, the procedure can yield viable infants in at least 15% of cases and occasionally alters maternal hemodynamics so as to restore the pulse in a clinically dead woman. This article reviews the physiology and hemodynamics of the maternal-fetal unit and discusses prognostic factors for the survival of healthy mother and infant, leading to recommendations for when to perform a perimortem cesarean section. The article then describes the technical aspects of the procedure.

The role of nuclear cardiology procedures in the evaluation of cardiac function following heart transplantation

Heart transplantation is, today, an accepted and recommended modality in the management of selected patients suffering from terminal heart disease. However, acute rejection and infection remain the major complications of this operation. Serial endomyocardial biopsy (EB), considered as the standard for diagnosis of cardiac rejection, is an invasive and delicate operation, not free of complications, even when done by skilled personnel in specialized centers. The object of this study was to compare and correlate between radionuclide ventriculography (RNV) and the histologic findings of EB. Furthermore, to validate the use of nuclear cardiology techniques that allow noninvasive, reliable, and rapid quantitation of ventricular function and myocardial perfusion for the diagnosis and management of rejection in patients with heart transplants. Radionuclide studies of left ventricular function were performed in 3 heterotopic heart transplant patients (HHT) with long term survival and early after the operation in 5 patients with HHT, 12 orthotopic heart transplants (OHT) and in 2 heart and lung transplants (HLT). Simultaneous EBs were performed in the early posttransplant patients and a histologic score for acute rejection was obtained. First pass (FP) and multigated equilibrium blood pool ventriculography, using the in vivo 99mTc-labelling of RBCs was used to measure left ventricular volumes (LVV) such as stroke volume (SV), end-diastolic volume (EDV), end-systolic volume (ESV), and both global and regional ejection fraction (EF, REF). The histological grading of acute rejection was classified into four groups: (1) no rejection, (2) mild rejection, (3) moderate rejection, and (4) severe rejection. The median of each LVV parameter was calculated and correlated with the EB using a nonparametric one way analysis of variance. A percentage change of LVVs was used rather than the difference of the calculated LVVs. During moderate acute rejection, SV had the highest correlation in P less than 0.004, followed by the EDV (P less than 0.05), and finally ESV (P less than 0.02). During severe acute rejection the correlation was SV (P less than 0.0008), EDV (P less than 0.001), and ESV (P less than 0.006). Myocardial perfusion scintigraphy using 201T1 was performed in the HHT patients, although, at this stage we have not attempted a correlation with the histologic findings. In one patient with long term survival OHT, increased 131I-metaiodobenzylguanidine (MIBG) myocardial uptake was evident during a rejection episode.

Late neuropathological consequences of strangulation

A case of a young man who was a victim of strangulation is presented. He arrived at the hospital in refractory status epilepticus, controlled only with intravenous pentobarbital. The initial CT scan showed mild cortical edema. Two days later, a CT scan showed diffuse cortical swelling and bilateral basal ganglia infarcts. Upon discontinuation of pentobarbital therapy, his neurological examination revealed spontaneous ventilation and a gag reflex. A CT scan 4 weeks after the insult demonstrated hypodensities in both cerebral hemispheres and hydrocephalus. EEG was isoelectric throughout his hospitalization. He survived nearly 5 months and succumbed to pneumonia. Neuropathological examination demonstrated severe encephalomalacia, multiple cystic infarcts and generalized compensatory ventriculomegaly. Microscopic examination was particularly remarkable for a pronounced gemistocytic astrocyte proliferation in the white matter. This case illustrates the long-term neuropathological consequences of severe, global hypoxia/ischemia and the paucity of intact brain required to maintain a persistent vegetative state.

Prognostic value of early cortical somatosensory evoked potentials after resuscitation from cardiac arrest

Short-latency somatosensory evoked potentials (SEPs) were evaluated in patients after cardiorespiratory arrest to study their pattern of recovery in the acute stage of anoxic-ischaemic coma. Fifty consecutive comatose patients were investigated within 8 h after cardiorespiratory resuscitation. In 30 patients no cortical SEPs were recorded and none of the patients recovered cognition. In 20 patients cortical SEPs were recorded and 5 recovered. The different susceptibility of frontal and parietal cortical structures to anoxia was reflected by the dissociated loss of parietal or frontal potentials in 6 patients. Post-mortem pathology in 15 patients confirmed extensive anoxic-ischaemic damage of cerebral and cerebellar cortex and thalamus in patients without cortical SEPs whereas the histological lesions were restricted to Sommer's sector and Purkinje cells in those with preserved SEPs. SEPs thus reflect the extent of brain damage after cardiorespiratory resuscitation.

Shock following generalized hypoxic-ischemic injury in previously healthy infants and children

Eighteen previously healthy patients with hypoxic-ischemic shock were observed longitudinally by means of data measured or derived from systemic arterial and pulmonary artery catheters. Shock was characterized by low cardiac index, elevated right and left heart filling pressures, elevated systemic and pulmonary vascular resistances, decreased oxygen consumption, and elevated oxygen extraction indices. Oxygen consumption was significantly correlated with oxygen delivery (r = 0.74, P less than 0.0001). This pattern fits that of cardiogenic shock. Cardiopulmonary data were not significantly different in survivors (n = 10) and nonsurvivors (n = 8). Outcome was determined by neurologic injury.

EEG features of the apallic syndrome resulting from cerebral anoxia

Three victims of severe cerebral anoxia developed the apallic syndrome, and clinical neurophysiological examinations documented slow evolution of a diurnal behavior pattern. Marked EEG attenuation was the primary finding, but all the patients exhibited clustering of quiescent periods at night, during which EEG waves were generated, and two stages suggested REM and non-REM sleep. The results seemed to confirm the notions that brain-stem mechanisms control occurrence of REM and non-REM sleep, and that forebrain mechanisms are required for development of differential EEG features of non-REM sleep stages (I through IV). It is also suggested that an extreme degree of attenuation resulting from EEG desynchronization in certain patients may closely resemble ECS.