Doppler transcraneal en el diagnóstico de la muerte encefálica. ¿Es útil o retrasa el diagnóstico?

Transcranial Doppler and Color-Coded Doppler Use for Brain Death Determination in Adult Patients: A Pictorial Essay

Transcranial Doppler (TCD) is a repeatable, at-the-bedside, helpful tool for confirming cerebral circulatory arrest (CCA). Despite its variable accuracy, TCD is increasingly used during brain death determination, and it is considered among the optional ancillary tests in several countries. Among its limitations, the need for skilled operators with appropriate knowledge of typical CCA patterns and the lack of adequate acoustic bone windows for intracranial arteries assessment are critical. The purpose of this review is to describe how to evaluate cerebral circulatory arrest in the intensive care unit with TCD and transcranial duplex color-coded doppler (TCCD).

Transcranial sonography in the critical patient

Transcranial ultrasonography is a non-invasive, bedside technique that has become a widely implemented tool in the evaluation and management of neurocritically ill patients. It constitutes a technique in continuous growth whose fundamentals (and limitations) must be known by the intensivist. This review provides a practical approach for the intensivist, including the different sonographic windows and planes of insonation and its role in different conditions of the neurocritical patients and in critical care patients of other etiologies.

Use of duplex echoencephalography to evaluate brain death in children: A novel approach to the diagnosis

BACKGROUND AND PURPOSE

Brain death is defined as the irreversible cessation of brain function with a known etiology. This study aims to establish the value of duplex echoencephalography (DEG) in children fulfilling clinical brain death diagnostic criteria.

METHODS

DEG must show intracranial brain structures. Power Doppler is used to assess venous flow when feasible. Color Doppler patterns in all major arteries are assessed. Spectral analysis of arterial flow is divided into four grades: grade 1: inverted flow during entire diastole with time average peak velocity (TAPV) less or equal to zero; grade 2: disappearance of the inverted diastolic flow at the end of diastole; grade 3: oscillating pattern in early diastole; and grade 4: no diastolic flow with systolic blip. To fulfill diagnosis of brain death, brain perfusion must be lost for 30 minutes.

RESULTS

DEG is performed in 41 pediatric patients. In infants, loss of venous flow occurs regardless of the etiology. Grade 1 is the most common arterial color flow pattern and TAPV is always below zero. A pulsatile color flow is associated with three other types of flow patterns (grades 2-4). TAPV is not calculated, when there is loss of diastolic flow. Diagnosis of brain death is validated using nuclear brain scan in 4 patients. Two have a grade 1 flow pattern, while the other two have a grade 4 flow pattern.

CONCLUSIONS

In children, DEG following a strict protocol can be used to confirm diagnosis of brain death in the appropriate clinical setting.

Transcranial Doppler analysis based on computer and artificial intelligence for acute cerebrovascular disease

Cerebrovascular disease refers to damage to brain tissue caused by impaired intracranial blood circulation. It usually presents clinically as an acute nonfatal event and is characterized by high morbidity, disability, and mortality. Transcranial Doppler (TCD) ultrasonography is a non-invasive method for the diagnosis of cerebrovascular disease that uses the Doppler effect to detect the hemodynamic and physiological parameters of the major intracranial basilar arteries. It can provide important hemodynamic information that cannot be measured by other diagnostic imaging techniques for cerebrovascular disease. And the result parameters of TCD ultrasonography such as blood flow velocity and beat index can reflect the type of cerebrovascular disease and serve as a basis to assist physicians in the treatment of cerebrovascular diseases. Artificial intelligence (AI) is a branch of computer science which is used in a wide range of applications in agriculture, communications, medicine, finance, and other fields. In recent years, there are much research devoted to the application of AI to TCD. The review and summary of related technologies is an important work to promote the development of this field, which can provide an intuitive technical summary for future researchers. In this paper, we first review the development, principles, and applications of TCD ultrasonography and other related knowledge, and briefly introduce the development of AI in the field of medicine and emergency medicine. Finally, we summarize in detail the applications and advantages of AI technology in TCD ultrasonography including the establishment of an examination system combining brain computer interface (BCI) and TCD ultrasonography, the classification and noise cancellation of TCD ultrasonography signals using AI algorithms, and the use of intelligent robots to assist physicians in TCD ultrasonography and discuss the prospects for the development of AI in TCD ultrasonography.

Clinico-radiological related to early brain death factors

OBJECTIVE

To identify clinical and radiological factors associated to early evolution to brain death (BD), defined as occurring within the first 24 h.

DESIGN

A retrospective cohort study was made covering the period 2015-2017.

SETTING

An adult Intensive Care Unit (ICU).

PATIENTS/METHODS

Epidemiological, clinical and imaging (CT scan) parameters upon admission to the ICU in patients evolving to BD.

RESULTS

A total of 166 patients with BD (86 males, mean age 62.7 years) were analyzed. Primary cause: intracerebral hemorrhage 42.8%, subarachnoid hemorrhage 18.7%, traumatic brain injury 17.5%, anoxia 9%, stroke 7.8%, other causes 4.2%. Epidemiological data: arterial hypertension 50%, dyslipidemia 34%, smoking 33%, antiplatelet medication 21%, alcoholism 19%, anticoagulant therapy 15%, diabetes 15%. The Glasgow Coma Score (GCS) upon admission was 3 in 68.8% of the cases in early BD versus in 38.2% of the cases in BD occurring after 24 h (p = 0.0001). Eighty-five patients presented supratentorial hematomas with a volume of 90.9 ml in early BD versus 82.7 ml in BD > 24 h (p = 0.54). The mean midline shift was 10.7 mm in early BD versus 7.8 mm in BD > 24 h (p = 0.045). Ninety-one patients presented ventriculomegaly and 38 additionally ependymal transudation (p = 0.021). Thirty-six patients with early BD versus 24 with BD > 24 h presented complete effacement of basal cisterns (p = 0.005), sulcular effacement (p = 0.013), loss of cortico-subcortical differentiation (p = 0.0001) and effacement of the suprasellar cistern (p = 0.005). The optic nerve sheath measurements showed no significant differences between groups.

CONCLUSIONS

Early BD (>24 h) was associated to GCS < 5, midline shift, effacement of the basal cisterns, cerebral sulci and suprasellar cistern, and ependymal transudation.

Clinico-radiological related to early brain death factors

OBJECTIVE

To identify clinical and radiological factors associated to early evolution to brain death (BD), defined as occurring within the first 24 hours.

DESIGN

A retrospective cohort study was made covering the period 2015-2017.

SETTING

An adult Intensive Care Unit (ICU).

PATIENTS/METHODS

Epidemiological, clinical and imaging (CT scan) parameters upon admission to the ICU in patients evolving to BD.

RESULTS

A total of 166 patients with BD (86 males, mean age 62.7 years) were analyzed. Primary cause: intracerebral hemorrhage 42.8%, subarachnoid hemorrhage 18.7%, traumatic brain injury 17.5%, anoxia 9%, stroke 7.8%, other causes 4.2%. Epidemiological data: arterial hypertension 50%, dyslipidemia 34%, smoking 33%, antiplatelet medication 21%, alcoholism 19%, anticoagulant therapy 15%, diabetes 15%. The Glasgow Coma Score (GCS) upon admission was 3 in 68.8% of the cases in early BD versus in 38.2% of the cases in BD occurring after 24 h (p = 0.0001). Eighty-five patients presented supratentorial hematomas with a volume of 90.9 ml in early BD versus 82.7 ml in BD >24 h (p = 0.54). The mean midline shift was 10.7 mm in early BD versus 7.8 mm in BD >24 h (p = 0.045). Ninety-one patients presented ventriculomegaly and 38 additionally ependymal transudation (p = 0.021). Thirty-six patients with early BD versus 24 with BD >24 h presented complete effacement of basal cisterns (p = 0.005), sulcular effacement (p = 0.013), loss of cortico-subcortical differentiation (p = 0.0001) and effacement of the suprasellar cistern (p = 0.005). The optic nerve sheath measurements showed no significant differences between groups.

CONCLUSIONS

Early BD (>24 h) was associated to GCS < 5, midline shift, effacement of the basal cisterns, cerebral sulci and suprasellar cistern, and ependymal transudation.

Intensive Care Unit Approach to the Diagnosis of Brain Death in Infratentorial Neurologic Pathology: Case Reports

The ischemic and primary vascular injury of the brainstem (BS) can determine, among other serious conditions, the brain death (BD) of the individual. We present 2 cases of individuals with primary ischemic vascular disease of the BS who evolved to BD and were donors of solid organs and tissues. In both cases, the clinical examination was positive for the diagnosis of BD, and transcranial Doppler did not confirm the pattern of cerebral circulatory arrest that accompanies BD. The magnetic resonance angiography performed on 1 patient confirmed the lesion etiology and the presence of vascular obstruction. Both patients were real and effective organ and tissue donors. In these cases, we suggest not to resort to transcranial Doppler as an auxiliary diagnostic test.

[Intensive care to facilitate organ donation. ONT-SEMICYUC recommendations]

Intensive care to facilitate organ donation (ICOD) is defined as the initiation or continuation of life-sustaining measures, such as mechanical ventilation, in patients with a devastating brain injury with high probability of evolving to brain death and in whom curative treatment has been completely dismissed and considered futile. ICOD incorporates the option to organ donation allowing a holistic approach to end-of-life care, consistent with the patients wills and values. Should the patient not evolve to brain death, life-supportive treatment must be withdrawal and controlled asystolia donation could be evaluated. ICOD is a legitimate practice, within the ethical and legal regulations that contributes increasing the accessibility of patients to transplantation, promoting health by increasing deceased donation by 24%, and with a mean of 2.3 organs transplanted per donor, and collaborating with the sustainability of health-care system. This ONT-SEMICYUC recommendations provide a guide to facilitate an ICOD harmonized practice in spanish ICUs.

The Role of Transcranial Doppler Ultrasonography in the Diagnosis of Brain Death

Ancillary tests can be used for the diagnosis of brain death in cases wherein uncertainty exists regarding the neurological examination and apnoea test cannot be performed. Transcranial Doppler ultrasonography (TCD) is a useful, valid, non-invasive, portable, and repeatable ancillary test for the confirmation of brain death. Despite its varying sensitivity and specificity rates with regard to the diagnosis of the brain death, its clinical use has steadily increased in the intensive care unit because of its numerous superior properties. The use of TCD as an ancillary test for the diagnosis of brain death and cerebral circulatory arrest is discussed in the current review.

Summary of Spanish recommendations on intensive care to facilitate organ donation

With the aim of consolidating recommendations about the practice of initiating or continuing intensive care to facilitate organ donation (ICOD), an ad hoc working group was established, comprising 10 intensivists designated by the Spanish Society of Intensive Care and Coronary Units (SEMICYUC) and the Spanish National Transplant Organization (ONT). Consensus was reached in all recommendations through a deliberative process. After a public consultation, the final recommendations were institutionally adopted by SEMICYUC, ONT, and the Transplant Committee of the National Health-Care System. This article reports on the resulting recommendations on ICOD for patients with a devastating brain injury for whom the decision has been made not to apply any medical or surgical treatment with a curative purpose on the grounds of futility. Emphasis is made on the systematic referral of these patients to donor coordinators, the proper assessment of the likelihood of brain death and medical suitability, and on transparency in communication with the patient's family. The legal and ethical aspects of ICOD are addressed. ICOD is considered a legitimate practice that offers more patients the opportunity of donating their organs upon their death and helps to increase the availability of organs for transplantation.

Ancillary Studies in Evaluating Pediatric Brain Death

When confounding variables exist that inhibit the ability to diagnose brain death clinically in pediatric patients, ancillary tests may provide additional information for the practitioner in evaluating for the presence or absence of brain death. Multiple options exist but differ in availability, ease of administration, cost, safety profile, and reliability to accurately diagnose brain death. An important desirable quality of an ancillary test is eliminating false positives, which imply brain death when brain death is in fact not present. More commonly available ancillary studies include electroencephalograms, brain angiography through various modalities, brain stem auditory evoked potentials, and transcranial Doppler ultrasound. At this time, there is not an ancillary test with 100% reliability in diagnosing brain death that can replace the clinical brain death exam. Therefore, practitioners need to understand the strengths and limitations of the ancillary studies available at their hospital.

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.