Aortocranial and carotid angiography in determination of brain death

Brain death and management of the potential donor

One of the first attempts to define brain death (BD) dates from 1963, and since then, the diagnosis criteria of that entity have evolved. In spite of the publication of practice parameters and evidence-based guidelines, BD is still causing concern and controversies in the society. The difficulties in determining brain death and making it understood by family members not only endorse futile therapies and increase health care costs, but also hinder the organ transplantation process. This review aims to give an overview about the definition of BD, causes, physiopathology, diagnosis criteria, and management of the potential brain-dead donor. It is important to note that the BD determination criteria detailed here follow the AAN’s recommendations, but the standard practice for BD diagnosis varies from one country to another.

[Angiographic procedures for determination of cessation of cerebral circulation]

In several European countries catheter angiography is permitted as a confirmatory procedure for the determination of irreversible loss of brain function (brain death). In Germany catheter angiography requires the possibility of a therapeutic implication as a prerequisite. In the updated German guidelines computed tomography angiography (CTA) has been accredited as a new confirmatory procedure if a standardized protocol and predefined assessment parameters are adhered to. The CTA can be performed within a few minutes, even in situations with unstable intensive care patients. Magnetic resonance (MR) angiography has not yet been adequately validated and is not permitted in Germany as a confirmatory procedure for the determination of irreversible loss of brain function.

Analytic Reviews : Organ Procurement and Brain Death in Trauma Patients

The success rates and effectiveness of transplantation programs continue to increase, as does the need for cadaveric organs. Increasing organ procurement is a worthwhile goal that can be fully justified on economic, humanistic, and ethical bases. Although a great deal of progress has been made in terms of public and political awareness of organ procurement problems, additional changes and further education will be necessary before the number of cadaveric organs that are needlessly wasted can be reduced.

Management of patients with unsurvivable head in juries or patients who are candidates for organ donation is a complex task involving critical care management, the declaration of brain death, and the identification of, and request for, organ donation from next of kin. This process involves the coordinated efforts of neurosur geons, critical care specialists, social workers, and the transplant team coordinators in organ procurement pro grams. Patients are best managed in tertiary centers that have staffs with the expertise and interest in performing these tasks. The time to cardiac death in brain-dead pa tients is frequently short and is hastened by the develop ment of rapidly progressive derangements in gas ex change, fluid and electrolyte homeostasis, temperature regulation, coagulation, and cardiovascular function. Premature death under these circumstances continues to be a major reason for organ-procurement failure. Ag gressive monitoring and treatment of the multiple med ical problems encountered, however, may reduce the number of patients who die prematurely and thus in crease organ procurement rates.

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.

Moderately elevated intracranial pressure produces greater cross-filling of the anterior communicating artery

This study aimed to investigate whether moderately elevated intracranial pressure is associated with greater cross-filling of the anterior communicating artery on diagnostic cerebral angiography. A retrospective study of 12 patients with subarachnoid hemorrhage was performed. Data on sequential cerebral angiograms and clinical data were used to indirectly estimate intracranial pressure (ICP). Cross-filling of the anterior communicating artery (ACom) was recorded according to our scoring system. Our study included 12 patients with mean age 43 ± 11 yrs. Six patients demonstrated greater ICP associated with greater cross-filling of the ACom on initial angiogram. One patient had greater ICP with greater cross-filling on follow-up angiogram secondary to infarction and midline shift. Two patients had lower ICP yet greater cross-filling on follow-up angiogram due to higher injection rate and volume. One patient with no change in ICP demonstrated the same degree of cross-filling. A markedly elevated ICP is traditionally associated with no cross-filling across the ACom. We propose a counter-intuitive model in which moderately elevated ICP produces greater cross-filling of the ACom. This diagnostic angiographic finding should make the angiographer consider that the patient has moderately elevated ICP, and facilitate more timely clinical management.

The degree of certainty in brain death: probability in clinical and Islamic legal discourse

The University of Michigan conference "Where Religion, Policy, and Bioethics Meet: An Interdisciplinary Conference on Islamic Bioethics and End-of-Life Care" in April 2011 addressed the issue of brain death as the prototype for a discourse that would reflect the emergence of Islamic bioethics as a formal field of study. In considering the issue of brain death, various Muslim legal experts have raised concerns over the lack of certainty in the scientific criteria as applied to the definition and diagnosis of brain death by the medical community. In contrast, the medical community at large has not required absolute certainty in its process, but has sought to eliminate doubt through cumulative diagnostic modalities and supportive scientific evidence. This has recently become a principal model, with increased interest in data analysis and evidence-based medicine with the intent to analyze and ultimately improve outcomes. Islamic law has also long employed a systematic methodology with the goal of eliminating doubt from rulings regarding the question of certainty. While ample criticism of the scientific criteria of brain death (Harvard criteria) by traditional legal sources now exists, an analysis of the legal process in assessing brain death, geared toward informing the clinician's perspective on the issue, is lacking. In this article, we explore the role of certainty in the diagnostic modalities used to establish diagnoses of brain death in current medical practice. We further examine the Islamic jurisprudential approach vis-à-vis the concept of certainty (yaqīn). Finally, we contrast the two at times divergent philosophies and consider what each perspective may contribute to the global discourse on brain death, understanding that the interdependence that exists between the theological, juridical, ethical, and medical/scientific fields necessitates an open discussion and active collaboration between all parties. We hope that this article serves to continue the discourse that was successfully begun by this initial interdisciplinary endeavor at the University of Michigan.

Monitoring and intraoperative management of elevated intracranial pressure and decompressive craniectomy

Elevated intracranial pressure can be caused by a variety of underlying conditions. Several physiologic and pharmacologic factors have a significant impact on intracranial hypertension, mostly caused by changes on cerebral blood volume, flow, and oxygenation. There are many therapies that can be used to decrease intracranial pressure ranging from pharmacologic to the surgical decompressive removal of the calvarium. Special consideration is made for the anesthetic management of these patients perioperatively.

Brazilian guidelines for the application of transcranial ultrasound as a diagnostic test for the confirmation of brain death

Neurosonological studies, specifically transcranial Doppler (TCD) and transcranial color-coded duplex (TCCD), have high level of specificity and sensitivity and they are used as complementary tests for the diagnosis of brain death (BD). A group of experts, from the Neurosonology Department of the Brazilian Academy of Neurology, created a task force to determine the criteria for the following aspects of diagnosing BD in Brazil: the reliability of TCD methodology; the reliability of TCCD methodology; neurosonology training and skills; the diagnosis of encephalic circulatory arrest; and exam documentation for BD. The results of this meeting are presented in the current paper.

Monitoring and intraoperative management of elevated intracranial pressure and decompressive craniectomy

There are numerous clinical scenarios wherein a critically ill patient may present with neurologic dysfunction. In a general sense these scenarios often involve ischemia, trauma, or neuroexcitation. Each of these may include a period of decreased cerebral perfusion pressure, usually due to elevated intracranial pressure (ICP), eventually compromising cerebral blood flow sufficiently to produce permanent neuronal loss, infarction, and possibly brain death. Elevated ICP is thus a common pathway for neural demise and it may arise from a variety of causes, many of which may result in a neurosurgical procedure intended to ameliorate the impact or etiology of elevated ICP.

Sensitivity of transcranial Doppler for confirming brain death: a prospective study of 270 cases

OBJECTIVE

The reported sensitivity of transcranial Doppler ultrasonography (TCD) for confirming brain death (BD) ranges from 91% to 100%. We assessed the frequency and causes of false-negative results in TCD examination in a series of patients with BD and in the literature.

METHODS

We carried out a prospective TCD examination of consecutive patients with the clinical diagnosis of BD.

RESULTS

In 204 (75.5%) of 270 patients, TCD showed a pattern compatible with BD. The causes of the false-negative results were persistent flow in the intracranial arteries in 47 (17.4%) patients and a lack of signal in 19 (7%). Absence of sympathomimetic drug use [odds ratio (OR) 5.4, 95% confidence interval (CI) 1.8-16.0, P = 0.003) and female gender (OR 3.7, 95% CI 1.1-12.5, P = 0.03) were associated with false-negative results. A review of 16 studies showed a sensitivity of 88% and a specificity of 98% of TCD for confirming BD.

CONCLUSIONS

The sensitivity of TCD for confirming BD may be lower than previously reported, but is probably similar to that of other non-invasive methods. The specificity of TCD is close to 100%. Uniform criteria are needed for the routine use of TCD as a confirmatory test for BD.

Persistence of isolated flow in the internal carotid artery in brain death

The criteria for the confirmation of brain death (BD) using transcranial Doppler ultrasonography (TCD) state that flow should not be observed in the internal carotid artery (ICA). In 94 brain-dead patients examined by TCD, 19 (20%) had flow in the ICA despite cerebral circulatory arrest. There was no difference in the clinical characteristics of patients with or without isolated flow in the ICA. Shunting of blood from the ICA into the external carotid system or the arrest of blood flow at a higher level than the carotid siphon may explain our findings. Our results show that the current TCD criteria can result in a high rate of false negatives. We suggest that the TCD criteria for the diagnosis of brain death should be reviewed.

Brain death and evoked potentials in pediatric patients

OBJECTIVE

To define the evoked potential responses (auditory and somatosensory) obtained from pediatric brain-dead patients.

DESIGN

Prospective study over an 8-yr period (1988-1996).

SETTING

A 14-bed pediatric intensive care unit in a multidisciplinary regional referral center (teaching hospital).

PATIENTS

Fifty-one pediatric patients with clinically established brain death.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Auditory brainstem and somatosensory evoked potentials were performed with a mean evolution time of 24 hrs after clinical brain death. The first brainstem auditory evoked potential recording was compatible with the diagnosis in 45 patients (90%): 27 patients (53%) did not respond, wave I was patent in 16 (7 bilateral, 6 from the left side, and 3 from the right side), and 2 patients evoked waves I and II in one or both ears. Gross anomalies were found in the remaining six patients. Sixteen patients were tested for somatosensory evoked potentials. N13 identifiable wave (62.5% of the patients) or a flat record were the obtained findings. Electric silence was noted initially on the electroencephalogram (EEG) in only 14 of 29 patients. Later flattening was observed in seven patients. Missing brainstem evoked response was noted earlier than cortical electric silence (range, 12-144 hrs). Any central wave could be pointed out in the evoked potentials of patients with an isoelectric EEG.

CONCLUSIONS

Evoked potential is useful in confirming the diagnosis of brain death in infants and in children as well as in adults. The test can be performed at bedside without interfering with patient care, and results are similar to those obtained in adult patients. Flattening of the EEG requires more time than achieving compatible evoked-potential responses.

Dynamic computed tomography of cerebral circulatory arrest

Cerebral circulatory arrest is the physiological vascular equivalent of brain death. A series of eight consecutive patients referred with a clinical diagnosis of cerebral death secondary to various causes exhibited stagnation of blood within major vessels at the base of the brain, and complete gross nonperfusion of cerebral tissue within the plane of section, to include the cerebral hemispheres, brainstem, and cerebellum. While clinical confirmation of brain death is mandatory, this study confirms that intravenous dynamic cranial computed tomography is an efficacious, noninvasive method that may be useful in the immediate evaluation of the generalized abnormal cranial perfusion peculiar to this condition.

Transcranial Doppler sonographic monitoring in the intensive care unit

Transcranial Doppler sonography noninvasively measures flow velocities within the basal cerebral arteries. It has been used for the management of patients with ischemic cerebrovascular disease and subarachnoid hemorrhage, as well as in the determination of brain death. Its role and technical limitations in the intensive care unit are reviewed.

Transcranial Doppler study of intracranial circulatory arrest

To investigate the hemodynamics of intracranial circulatory arrest, the authors correlated the findings of noninvasive transcranial Doppler ultrasonography (TCD) with those of transfemoral four-vessel angiography in 65 patients following brain death and intracranial circulatory arrest due to severe intracranial hypertension. The three TCD stages of intracranial circulatory arrest, which have been described previously, corresponded with different levels of extracerebral angiographic cessation of flow. With TCD progression from the first stage (oscillating flow) to the third stage (no flow), the level where the dye stopped descended caudad from subarachnoid to cervical levels. The study shows that, in progressing intracranial hypertension, arterial circulatory standstill within the cranial cavity develops in a distal-to-proximal direction. The basal cerebral arteries remain patent in the early stages of intracranial circulatory arrest. Experimental evidence from the literature, together with the findings of the present investigation, points to the capillary bed as the initial site of the flow obstruction in progressing intracranial hypertension.

Transcranial pulsed Doppler ultrasound findings in brain stem death

Data are presented from transcranial insonation of the middle cerebral artery (MCA) performed at intervals in 23 unconscious children for whom the outcome was subsequently poor. Once an MCA signal had been observed over a 30 minute period with time averaged velocity less than 10 cm s-1 and/or a direction of flow index, DFI, defined as 1 minus the ratio of reverse to forward flow of less than 0.8, recovery to forward flow throughout diastole was never observed and no patient recovered brain stem reflexes. Recovery of forward flow in diastole, and of brain stem function, was seen in cases with time averaged MCA velocity in the range 10 to 25 cm s-1 and with reverse flow but a DFI of greater than 0.8 for short periods of time. All but one of the 13 children fulfilling clinical criteria for brain stem death had MCA signals with time averaged velocity of less than 10 cm/s and DFI of less than 0.8. This type of signal was not observed in five children who were left in a persistent vegetative state.

Computed tomography of the normal and abnormal superior sagittal sinus

The appearances on computed tomography (CT) of the normal and abnormal superior sagittal sinuses are presented. The varied patterns of non-enhanced and enhanced normal superior sagittal sinuses are correlated with and reflect the findings of anatomical dissection. Cases of abnormal superior sagittal sinus include thrombosis, brain death and sinus displacement.

Computer tomography in cerebral death

Computer tomography has been applied in a material of six patients meeting the criteria for cerebral death. The primary intracranial pathology, haemorrhages, infarction and contusions were demonstrable. No generalized reduction of the attenuation characteristic of infarction was found in spite of angiographic arrest of the intracranial circulation. Compression and obstruction of small brain vessels may in some cases be the primary cause of arrest of the brain circulation in cerebral death and not an increase of the intracranial pressure to levels approaching or surpassing the mean systemic arterial pressure.