Brain Death: Assessment, Controversy, and Confounding Factors

Computed Tomography Angiography (CTA) in Selected Scenarios with Risk of Possible False-Positive or False-Negative Conclusions in Diagnosing Brain Death

It is widely accepted that brain death (BD) is a diagnosis based on clinical examination. However, false-positive and false-negative evaluation results may be serious limitations. Ancillary tests are used when there is uncertainty about the reliability of the neurologic examination. Computed tomography angiography (CTA) is an ancillary test that tends to have the lowest false-positive rates. However, there are various influencing factors that can have an unfavorable effect on the validity of the examination method. There are inconsistent protocols regarding the evaluation criteria such as scoring systems. Among the most widely used different scoring systems the 4-point CTA-scoring system has been accepted as the most reliable method. Appropriate timing and/or Doppler pre-testing could reduce the number of possible premature examinations and increase the sensitivity of CTA in diagnosing cerebral circulatory arrest (CCA). In some cases of inconclusive CTA, the whole brain computed tomography perfusion (CTP) could be a crucial adjunct. Due to the increasing significance of CTA/CTP in determining BD, the methodology (including benefits and limitations) should also be conveyed via innovative electronic training tools, such as the BRAINDEXweb teaching tool based on an expert system.

Higenamine exerts an antispasmodic effect on cold-induced vasoconstriction by regulating the PI3K/Akt, ROS/α2C-AR and PTK9 pathways independently of the AMPK/eNOS/NO axis

The present study aimed to investigate the antispasmodic effect of higenamine on cold-induced cutaneous vasoconstriction and the underlying molecular mechanisms. A cold-induced cutaneous vasoconstriction rat model was established and different doses of higenamine were delivered by intravenous injection. The changes of cutaneous regional blood flow (RBF) between groups were analyzed. In vitro, the proliferation of human dermal microvascular endothelial cells was measured by MTT. The NO concentration was detected by a nitrate reductase assay. Flow cytometry was applied to measure reactive oxygen species (ROS) levels. The protein expression levels were detected by western blotting. The results demonstrated that in the model group, RBF declined compared with the normal control group, but was reversed by treatment with higenamine. The expression of endothelial nitric oxide synthase (eNOS), phosphorylated (p)-eNOS, protein kinase B (Akt1), p-Akt1, AMP-activated protein kinase (AMPK) α1 and p-AMPKα1 was upregulated by hypothermic treatment but was reversed by higenamine treatment. Treatment with higenamine significantly reduced the level of intracellular α2C-adrenoreceptor (AR) compared with the hypothermia group (P<0.05). Furthermore, the expression of twinfilin-1 (PTK9) was downregulated in the higenamine and positive control groups compared with the hypothermia group (P<0.05). Compared with the hypothermia group, the levels of ROS and α2C-AR (intracellular & membrane) were decreased in higenamine and the positive control group (P<0.05 and P<0.01, respectively). This study, to the best of our knowledge, is the first to assess the effects of higenamine on cold-induced vasoconstriction in vivo and its molecular mechanisms on the PI3K/Akt, AMPK/eNOS/nitric oxide, ROS/α2C-AR and PTK9 signaling pathways under hypothermia conditions. Higenamine may be a good therapeutic option for Raynaud's phenomenon (RP) and cold-induced vasoconstriction.

Performing the Brain Death Examination and the Declaration of Pediatric Brain Death

Declaration of brain death is a clinical diagnosis made by the absence of neurological function in a comatose patient secondary to a known irreversible cause. Brain death determination is not an infrequent process in pediatric intensive care units. It is important that pediatric intensive care providers understand the definition of brain death and intensivists are able to implement brain death testing. The following is a narration detailing the process of brain death determination by physical examination. First, the prerequisites that determine patients' eligibility for brain death testing will be outlined. Next, each part of the physical exam, including the apnea test, will be described in detail. Finally, how the declaration of brain death is made is stated. In addition, special considerations and ancillary testing will be briefly highlighted.

Use of Transcranial Doppler Ultrasound for Diagnosis of Brain Death in Patients with Severe Cerebral Injury

Background

The aim of this study was to investigate the use of transcranial Doppler (TCD) for diagnosis of brain death in patients with severe cerebral injury.

Material/Methods

This retrospective study enrolled 42 patients based on inclusion and exclusion criteria. All patients were divided into either the brain death group or the survival group according to prognosis. Blood flow of the brain was examined by TCD and analyzed for spectrum changes. The average blood flow velocity (Vm), pulse index (PI), and diastolic blood flow in reverse (RDF) were recorded and compared.

Results

The data demonstrated that the average speed of bilateral middle cerebral artery blood flow in the brain death group was significantly reduced (P<0.05). However, the PI of the brain death group increased significantly. Moreover, RDF spectrum and nail-like sharp peak spectrum of the brain death group was higher than in the survival group.

Conclusions

Due to its simplicity, high repeatability, and specificity, TCD combined with other methods is highly valuable for diagnosis of brain death in patients with severe brain injury.

Subtotal Cerebral Circulatory Arrest With Preserved Breathing Activity: A Case Report

A suspicion of brain death (BD) is the 1st step in the process of BD certification. Owing to its utmost importance, the process must yield an unequivocal answer so that the committee for the determination of BD has no doubts. We present a case of a patient with suspected BD, with a diagnosis of no intracranial flow in 4-vessel digital-subtraction angiography, who developed some reflexes just before clinical examination for BD assessment. The source of clinical findings was determined to be an extracranial blood supply, which enabled the preservation of trace lower brain stem functioning.