Assessment Of Brain Death Research Articles

Functional near infrared spectroscopy in the noninvasive assessment of brain death.

Brain death, whose assessment is of great significance, is the irreversible loss of all the functions of the brain and brainstem. The traditional diagnostic methods mainly relies on complex, harmful or unstable test, including apnea test,textbf evoked potential test, etc. Functional near infrared spectroscopy (fNIRS) utilize the good scattering properties of blood corpuscle to NIR, has the ability to monitor cerebral hemodynamics noninvasively. To objectively evaluate the brain death diagnosis with fNIRS, we use our portable fNIRS oximeter to measure the physiological data of fifteen brain death patients and twenty-two patients under natural state. The varied fractional concentration of inspired oxygen (FIO2) were provided in different phase. We found that the ratio ofthe concentration changes in oxy-hemoglobin to deoxy-hemoglobin(Δ[HbO2]/Δ[Hb])in normal patients is significantly lower than brain death patients, and its restore oxygen change process in low-high-low paradigm is more remarkable. This resulting promotion indicates potential of fNIRS-measured hemodynamic index in diagnosing brain death.

Predisposing Hemodynamic Factors Associated with a Failed Apnea Test during Brain Death Determination

Background: The apnea test is an essential component in the clinical determination of brain death, however it may incur a significant risk of complications such as hypotension, hypoxia and even cardiac arrest. We analyzed the risk factors associated with a failed apnea test during brain death assessment in order to predict and avoid these adverse events. Methods: Medical records on apnea tests performed for brain-dead donors at our institution between January 2009 and January 2016 were retrospectively reviewed. Age, gender, etiology of brain death, use of catecholamines and results of arterial blood gas analysis (ABGA), systolic/diastolic blood pressure (SBP/DBP), mean arterial pressure and central venous pressure prior to apnea test initiation were collected as variables. A-a gradient and PaO2/FiO2 were calculated for more precise assessment of the respiratory system. In total, 267 cases were divided into two groups based on those who completed the apnea test and those who failed the test. Results: 13 cases failed the apnea test. Among them, seven cases failed due to severe hypotension (SBP < 60 mmHg) and the others failed due to refractory hypoxia. In terms of hemodynamic state, SBP was significantly higher in the completed test group than the failed group (126.5 ± 23.9 vs. 103 ± 15.2, respectively; p = 0.001). In ABGA, the completed test group showed significantly higher PaO2/ FiO2 (313.6 ± 229.8 vs. 141.5 ± 131.0, respectively; p = 0.008) and a lower A-a gradient (278.2 ± 209.5 vs. 506.2 ± 173.1, respectively; p = 0.000). In multivariable analysis, low SBP (p = 0.003) and high A-a gradient (p = 0.044) were independent risk factors associated with a failed apnea test. Conclusions: Although the unexpected adverse events during the apnea test for brain death determination do not occur frequently, they can be fatal. If a brain-dead patient has low SBP and a high A-a gradient, clinicians should pay more attention and prepare for potential complications prior to the apnea test.

Cerebral perfusion measurement in brain death with intravoxel incoherent motion imaging

The assessment of brain death can be challenging in critically ill patients, and cerebral perfusion quantification might give information on the brain tissue viability. Intravoxel incoherent motion perfusion imaging is a magnetic resonance imaging technique, which extracts perfusion information from a diffusion-weighted sequence, and provides local, microvascular perfusion assessment without contrast media injection. Diffusion weighted images were acquired with 16 b-values (0–900 s/mm2) in the brain in two patients with cerebral death, confirmed by clinical assessment and evolution, as well as in two age-matched healthy subjects. The intravoxel incoherent motion perfusion fraction maps were obtained by fitting the bi-exponential signal equation model. 8 regions of interest were drawn blindly in the brain neocortex (in the frontal, temporal, parietal, and occipital lobes on both sides) and perfusion fractions were compared between patients with cerebral death and healthy control. Statistical significance was assessed using two-sided Wilcoxon signed rank test, and set to α < 0.05. Intravoxel incoherent motion (IVIM) perfusion fraction was vanishing in the brain of the two patients with cerebral brain death compared to the healthy controls. Mean (± standard deviation) cortex perfusion fraction was 0.016 ± 0.005 respectively 0.005 ± 0.008 in the cerebral death patients, compared to respectively 0.052 ± 0.021 (p = 0.02) and 0.071 ± 0.042 (p = 0.008) in the age-matched controls. Intravoxel incoherent motion perfusion imaging is a promising tool to assess local brain tissue viability in critically ill patients.

Apnea test during brain death assessment in mechanically ventilated and ECMO patients.

To evaluate the feasibility and efficacy of an apnea test (AT) technique that combines the application of positive end expiratory pressure (PEEP) with subsequent pulmonary recruitment in a large cohort of brain-dead patients. This study was a retrospective analysis of prospectively collected data on brain-dead patients admitted to our institution (Hospital San Gerardo, Monza, Italy) between January 2010 and December 2014. The rate of aborted apnea tests (ATs), occurrence of complications (i.e., pneumothorax, cardiac arrhythmias, cardiac arrest, and severe hypoxia, defined as PaO2 < 40 mmHg), ventilator settings, hemodynamics, and blood gas analyses were evaluated. Subgroup analysis was performed, with patients classified into veno-arterial extracorporeal membrane oxygenation (ECMO) or non-ECMO groups, and into hypoxic (i.e., baseline PaO2/FiO2 < 200 mmHg) and non-hypoxic (i.e., baseline PaO2/FiO2 > 200 mmHg) groups. In total, 169 consecutive patients including 25 on ECMO were included in the study. No AT abortion nor severe complications were detected. The AT was completed in all patients. Fluid boluses and increases or initiation of vasoactive drugs were required in less than 10 and 3% of the AT procedures, respectively. No clinically meaningful alteration in hemodynamics was recorded. Severe hypoxia occurred during 7 (2.4%) and 4 (8%) of the ATs performed in non-ECMO and ECMO patients, respectively (p = 0.063), and it occurred more frequently in hypoxic patients than in non-hypoxic patients (11.1 vs. 4.8%, respectively; p = 0.002). In a large cohort of consecutive patients, including the largest patient population on ECMO reported to date, our AT technique that combines the application of PEEP with subsequent pulmonary recruitment proved to be feasible and safe.

Renaissance of criticism on the concept of brain death--the role of legal medicine in the context of the interdisciplinary discussion.

In the practice of legal medicine in Germany, the assessment of brain death is of minor importance and attracts little attention. However, since several years, international criticism on the concept of brain death has culminated. By reviewing literature and the results of a questionnaire distributed among the participants of the 93rd Annual Congress of the Germany Society of Legal Medicine, the state of knowledge and the current views on brain death were evaluated. Literature search of recent publications regarding brain death was performed (PubMed database, references of legal medicine, Report of the President's Council on Bioethics, USA 2008). A questionnaire was developed and distributed among the participants of the Congress. The assumption that individual and brain death are synonymous is criticized. Internationally, there are trends to harmonize the very different clinical criteria to assess brain death. The diagnostic advantage of novel techniques such as CT angiography is controversially discussed. It becomes apparent that procedures which record the blood flow and perfusion of the brain will be applied more in the future. Regrettably, these developments are not described in the literature of legal medicine. Moreover, among German forensic scientists, different views concerning brain death exist. The majority favors its equivalent treatment with individual death. The thanatological background can be improved concerning certain aspects of brain death as well as its legal implications. Teaching and research in legal medicine should include the subject brain death. Expertise in forensic science may contribute to the interdisciplinary discussion on brain death. The transfer of actual knowledge, also on disputed ethical aspects of thanatology, to physicians of all disciplines is of great importance.

A new technique for avoiding barotrauma-induced complications in apnea testing for brain death

Prompted by our experience with complications occurring with apnea testing (AT), we discuss complications reported in the literature. AT is an integral part of brain death assessment. Many complications of AT have been described, including hypoxemia, arterial hypotension, tension pneumothorax and cardiac arrest. We conclude that a commonly used technique in conducting AT can create auto-positive end expiratory pressure (PEEP) and contributes to many complications. The mechanism of occult auto-PEEP in AT is discussed. Intensive care unit patients may have a compensated and asymptomatic relative hypovolemia that can be decompensated by a small amount of auto-PEEP produced by air trapping during insufflating oxygen (O2) through a 7.0 endotracheal tube (ETT). It could then lead to decreased preload, decreased stroke volume, decreased cardiac output and thus, to hypotension and a compensatory tachycardia. The placement of the standard O2 tubing (6mm outside diameter [OD]) inside the 7.0 ETT (7mm inside diameter [ID]) greatly decreased the ETT lumen (73%). We changed our practice to instead use readily available small pressure tubing to insufflate O2 for AT to avoid excessive reduction in the ETT lumen. The change from standard O2 tubing (6mm OD) to pressure tubing (3mm OD) will greatly decrease the reduction in cross-sectional area of 7.0 ETT lumen from 73 to 18% and avoid potential complications of air trapping, auto-PEEP and barotrauma. We have successfully used this new simple technique with readily available equipment to eliminate auto-PEEP in AT while preserving oxygenation.

Teaching the Concept of Brain Death in Undergraduate Medical Education

To establish and evaluate a new approach to teach medical students how to assess brain death in patients. A total of 120 fourth-year medical students at Münster Medical School (Germany) participated in a 1-hour lecture on how to assess brain death in patients. After this lecture, students were assigned to 2 groups. One group attended an additional practical course on the evaluation of brain death and received training using a new high-fidelity simulation device. The other group did not participate in any additional training session. All students completed a questionnaire before the lecture and a second questionnaire at the conclusion of the study. For the group undergoing the additional training, the second questionnaire was completed after the additional training session. The additional practical training session significantly improved the students' performance in assessing brain death and promoted the self-assessment and motivation of the medical students. The establishment of a new practical teaching concept led to significant improvements in medical students' assessments of brain death in a practical session. These improvements in medical education could have significant implications for the clinical assessment of patients in the future.

Human Brain Activity Patterns beyond the Isoelectric Line of Extreme Deep Coma

The electroencephalogram (EEG) reflects brain electrical activity. A flat (isoelectric) EEG, which is usually recorded during very deep coma, is considered to be a turning point between a living brain and a deceased brain. Therefore the isoelectric EEG constitutes, together with evidence of irreversible structural brain damage, one of the criteria for the assessment of brain death. In this study we use EEG recordings for humans on the one hand, and on the other hand double simultaneous intracellular recordings in the cortex and hippocampus, combined with EEG, in cats. They serve to demonstrate that a novel brain phenomenon is observable in both humans and animals during coma that is deeper than the one reflected by the isoelectric EEG, and that this state is characterized by brain activity generated within the hippocampal formation. This new state was induced either by medication applied to postanoxic coma (in human) or by application of high doses of anesthesia (isoflurane in animals) leading to an EEG activity of quasi-rhythmic sharp waves which henceforth we propose to call ν-complexes (Nu-complexes). Using simultaneous intracellular recordings in vivo in the cortex and hippocampus (especially in the CA3 region) we demonstrate that ν-complexes arise in the hippocampus and are subsequently transmitted to the cortex. The genesis of a hippocampal ν-complex depends upon another hippocampal activity, known as ripple activity, which is not overtly detectable at the cortical level. Based on our observations, we propose a scenario of how self-oscillations in hippocampal neurons can lead to a whole brain phenomenon during coma.

What's in this issue?

What's in this issue?

Apnea Test for Brain Death Determination in a Patient on Extracorporeal Membrane Oxygenation

Apnea test is a key component to confirm brain death. For patients receiving extracorporeal membrane oxygenation (ECMO), apnea test remains challenging. Brain death (BD) diagnosis is often made without apnea test. We report the case of a 29-year-old man presenting clinical signs of BD while treated with ECMO therapy for refractory cardiogenic shock. Decreasing the ECMO sweep gas flow from 3 to 1 L/min and increasing oxygen delivery to 100% on ECMO during the apnea test have allowed increasing the PaCO2 of more than 20 mmHg without decreasing PaO2. In order to diagnose BD, neurological examination should be complete, including apnea testing, which can be not possible in patients receiving ECMO due to CO2 removal from the membrane. Decreasing sweep gas rate allows reduction in CO2 diffusion through the membrane. However, decreasing the ECMO gas flow to zero could be insufficient to maintain normoxemia. Decreasing (but not stopping) the sweep gas flow to 1 L/min and increasing the oxygen delivery through the ECMO have allowed performing the apnea test safely. To assess brain death in patients on ECMO, apnea test can be performed without compromising oxygenation by decreasing (but not stopping) the sweep gas flow and increasing oxygen delivery through the membrane.

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.

Apnea Testing During Brain Death Assessment: A Review of Clinical Practice and Published Literature

The diagnosis of brain death is a complex process. Strong knowledge of neurophysiology and an understanding of brain death etiology must be used to confidently determine brain death. The key findings in brain death are unresponsiveness, and absence of brainstem reflexes in the setting of a devastating neurological injury. These findings are coupled with a series of confirmatory tests, and the diagnosis of brain death is established based on consensus recommendations. The drive to breathe in the setting of an intense ventilatory stimulus (ie, respiratory acidosis) is a critical marker of brainstem function. As a consequence, apnea testing is an important component of brain death assessment. This procedure requires close monitoring of a patient as all ventilator support is temporarily removed and Paco2 levels are allowed to rise. A "positive" test is defined by a total absence of respiratory efforts under these conditions. While apnea testing is not new, it still lacks consensus standardization regarding the actual procedure, monitored parameters, and evidence-based safety measures that may be used to prevent complications. The purpose of this report is to provide an overview of apnea testing and discuss issues related to the administration and safety of the procedure.

Pitfalls in Brain Death Diagnosis: A Case Report

Although there are distinct guidelines in nearly all countries, a reliable secure assessment of brain death in cases with open head injury can be challenging. We present a case of a 32-year-old man with severe head injury after intracranial penetration of a grindstone fragment. As the injury led to destruction of nearly the whole greater wing of the right sphenoid bone and parts of the right orbit, the examination of brainstem reflexes and the confirmation of brain death was unfeasible. On day 2, all clinical criteria of brain death (coma, absence of brainstem reflexes, apnea) were fulfilled. In addition, there was an extinction of brainstem auditory (BAEP) and cerebral (N20) components of median nerve somatosensory evoked potentials, while electroencephalogram (EEG) activity was still present. In the following days, a persisting EEG activity was obtained. Thus, an irreversible loss of whole brain functions could not be proved. As the patient had agreed to organ donation in case of brain death several years ago, ancillary methods to test the cessation of cerebral blood flow were mandatory. However, in this patient these methods turned out either to be doubtful or unavailable. For example, values of transcranial Doppler ultrasonography are not reliable in cases with open head injury. Due to a progressive septic state, time was running out to get the radiopharmaceutical agent for a cerebral scintigraphy (delivery time about 7 days, as the radiopharmaceutical agent was not in stock). Referring to the actual German guidelines, we had no legitimating indication for a cerebral angiography. Finally, the patient died of sepsis. We discuss the widening of the German guidelines in assessing brain death with the fast and low-risk method of cerebral computed tomography-angiography (CTA) to confirm diagnosis of brain death.

CT and MR perfusion can discriminate severe cerebral hypoperfusion from perfusion absence: evaluation of different commercial software packages by using digital phantoms

Computed tomography perfusion (CTP) and magnetic resonance perfusion (MRP) are expected to be usable for ancillary tests of brain death by detection of complete absence of cerebral perfusion; however, the detection limit of hypoperfusion has not been determined. Hence, we examined whether commercial software can visualize very low cerebral blood flow (CBF) and cerebral blood volume (CBV) by creating and using digital phantoms. Digital phantoms simulating 0-4% of normal CBF (60mL/100g/min) and CBV (4mL/100g/min) were analyzed by ten software packages of CT and MRI manufacturers. Region-of-interest measurements were performed to determine whether there was a significant difference between areas of 0% and areas of 1-4% of normal flow. The CTP software detected hypoperfusion down to 2-3% in CBF and 2% in CBV, while the MRP software detected that of 1-3% in CBF and 1-4% in CBV, although the lower limits varied among software packages. CTP and MRP can detect the difference between profound hypoperfusion of <5% from that of 0% in digital phantoms, suggesting their potential efficacy for assessing brain death.

Analysis of the Potential Deceased Donors in the Neurosurgical Intensive Care Units of Korea

Results: There were 1,166 males (58.9%) and 793 females (40.1%) with a mean age of 57.6±18.0 years (21.2% in the 5th decade; 21.0% in the 6th decade). The most common cause of death of PDDs was cerebrovascular accident (n=1,034; 52.2%). Glasgow Coma scale was 3 in 23.1% and 4 in 12.1% of the PDDs. Craniotomy was performed in 996 patients (50.3%). Sepsis developed in 276 patients (14.0%) among the total PPDs. Diagnostic procedure for assessment of brain death was performed in 194 patients (9.8%). The seroprevalence of HBsAg and HCVAb was 1.7% and 0.6%, respectively. The mean AST/ALT level on admission and after brain death were 80.9±344.9/49.0±162.19 and 308.6±1,485.2/142.5±596.27 IU/L, respectively. Uriney protein level was normal in 1,221 patients (61.7%) after brain death. Of the 1980 PDDs, 19 patients (1%) donated their organs for transplantation. Conclusion: Only a small percentage (1%) of PDDs in the NICU donated their organs in Korea. We suggest that continuous and active donor action is needed to increase organ donation from the potential deceased donors.

Identification of potential organ donors of advanced age in EDs

Objective In France and in Belgium, as in many countries, there is a shortage of organs for transplantation, which has led to strategies to recruit older potential donors who may die of stroke. Methods We conducted a post hoc analysis to identify potential organ donors with cardiac function among a population of dying patients in emergency departments. This population had been selected for a separate multicenter prospective observational study. We identified patients who died of a neurologic cause but had no clinical findings affecting their donor status. Results Of 2420 patients in the study, 407 died of a neurologic cause; and 233 of these were excluded because of clinical factors that made them ineligible as organ donors. The remaining 174 patients (7.2% of dying patients) could be considered potential organ donors. Their mean age was 75.2 ± 11 years. Sixty-eight (39%) were intubated, and 60 of these (34.5%) were mechanically ventilated. In addition, 94 patients (54%) died within 12 hours (median, 9.3 hours) after admission; and 13 (7%) died while receiving a maximum level of care. No diagnostic procedures were performed to assess brain death. Conclusion A significant number of patients who die in emergency departments could be organ donors, including approximately 7% between 60 and 85 years of age with life-threatening neurologic diseases. However, this percentage may be reduced by family opposition. Emergency physicians should collaborate with intensive care units and local organ donation teams to optimize end-of-life care and maximize the number of potential donors.

Imaging tests in determination of brain death

Imaging tests in determination of brain death

The Role of Nurses in the Risk Management of Organ and Tissue Donation

In the setting of organ and tissue procurement, lack of transplantation and the resulting missed opportunity for wait-listed patients might be considered as an untoward effect, since it results in longer wait-list times, higher mortality rates for potential candidates, and harm to the entire society. Beyond the classical definition holding that an adverse event is the inadvertent transmission of disease from a donor to a recipient, we advocate it should also include nonreporting of potential deceased donors; unsuccessful donor management; failure in organ/tissue procurement as the result of impossibility to assess brain death, lack of clinical data, or technical problems during surgical procedures. Based on their education, experience, and competencies, nurses share the responsibility to participate in the evaluation of risks and in the implementation of appropriate strategies for error prevention during the entire procurement process.

Assessment of brain death of organ donors in Iran

Assessment of brain death of organ donors in Iran

Intérêt de l’angioscanner corps entier dans la prise en charge du patient en état de mort encéphalique

To assess the value of whole body CTA, as a complement to head CTA, in the management of brain-dead patients as potential organ donors. Materials and Methods. A total of 27 consecutive brain-dead patients admitted in a center authorized in the harvesting of organs between October 2006 and January 2008 were included. The imaging protocol used was the protocol recommended by the French Society of Neuroradiology, with additional arterial phase helical acquisition of the chest, abdomen and pelvis, and parenchymal phase helical acquisition of the abdomen and pelvis. The imaging findings were then correlated to the surgical reports after organ harvesting. CTA readily demonstrates tissue lesions, a contraindication to harvesting (14 cases, including one false positive), and anatomical variants of the vascular system (7 arterial variants and 3 venous variants) and liver (8 patients). CTA, the gold standard paraclinical examination for brain death assessment, allows, in a single examination, the identification of contraindications to organ harvesting that may modify the surgical approach and even avoid unnecessary mobilisation of the transplant team. It may also provide valuable preoperative evaluation by detecting anatomical variants of the liver and kidneys.