Persistence of intracranial diastolic flow in transcranial Doppler sonography exploration of patients in brain death

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.

[Prospective investigation of extracranial duplex sonography for the detection of cerebral circulatory arrest in patients with irreversible loss of brain function]

BACKGROUND

A broader distribution of bedside color-coded duplex sonography (CCD) for detection of cerebral circulatory arrest (CCA) would be important to improve its use in the diagnosis of irreversible loss of brain function (ILBF-Dx).

QUESTION

Is extracranial compared to the commonly applied transcranial CCD of the brain-supplying vessels (ECCD vs. TCCD) equivalent for the detection of CCA in ILBF-Dx regarding specificity and sensitivity?

MATERIAL AND METHODS

Study period January 2019-June 2022, screening of 136 and inclusion of 114 patients with severe brain lesions > 24 h after onset of fixed and dilated pupils, apnea and completed ILBF-Dx. Exclusion of patients without brainstem areflexia and guideline-conform applicability of CCD. Complementary ECCD (and TCCD, if other method used for irreversibility detection).

RESULTS

Detection of ILBF (ILBF+) in 86.8% (99/114), no ILBF (ILBF-) in 13.2% (15/114). ECCD was fully feasible in all patients; findings matching CCA were found in 94/99 ILBF+ cases (ECCD+) and not in 5 patients (ECCD-). All 15 patients with ILBF- showed ECCD- findings. Thus, the specificity of ECCD was 1.0, and the sensitivity was 0.949. TCCD showed CCA in 56 patients (TCCD+), and ECCD+ was also found in all of them. An inconclusive result of TCCD in ILBF+ was found in 38 cases, with parallel ECCD+ in all of these patients. In 20 cases, TCCD did not show CCA (TCCD-), these also showed ECCD-. Of these patients 15 were ILBF- and 5 were ILBF+.

DISCUSSION

TCCD was not completely feasible or inconclusive in one third of the cases, whereas ECCD was always feasible. ECCD showed high validity with respect to the detection of CCA. Therefore, the possibility of using ECCD alone to detect CCA in ILBF-Dx should be discussed.

Impact of decompressive craniectomy on brain perfusion scintigraphy as an ancillary test for brain death diagnosis

OBJECTIVES

Decompressive craniectomy is occasionally performed for patients with impending brain death, which is intended to relieve critically elevated intracranial pressure to keep effective intracranial perfusion. It has been in debate if this surgery later affects the result of brain perfusion scintigraphy performed as an ancillary test in the course of brain death diagnosis because rigid closed skull is deemed essential to elevate intracranial pressure to the point of total absence of intracranial radiotracer uptake on scintigraphy. The purpose of this study is to elucidate the impact of decompressive craniectomy on the result of brain perfusion scintigraphy in patients with suspected brain death.

METHODS

This retrospective cross-sectional study included consecutive 151 brain perfusion scintigraphy performed in 138 patients with suspected brain death from various causes (male 82 patients, female 56 patients; range 0-74 years; mean age 36.6 years). All exams were indicated due to inconclusive clinical diagnosis of brain death. The scintigraphy protocol consists of immediate flow phase and delayed parenchymal phase planar imaging. Additional SPECT imaging was performed in 15 studies in 14 patients. The results, positive or negative brain flow, were compared between patients with and without decompressive craniectomy using Chi-squared test. As there were patients with repeat studies, analysis was performed for both initial and final exam results. Same dataset was used for initial and final exams in patients with only one exam.

RESULTS

Out of 138 patients, 15 patients underwent decompressive craniectomy (11%) and 123 patients were managed medically (89%). On the initial exam, negative brain flow was demonstrated in 11 of 15 patients with craniectomy (73.3%) and 106 of 123 patients without craniectomy (86.2%). On the final exam, negative brain flow was demonstrated 12 of 15 patients with craniectomy (80%) and 111 of 123 patients without craniectomy (90.2%). There were no statistically significant differences between the two groups on both initial and final exams (p = 0.19 and 0.23, respectively).

CONCLUSION

In patients with suspected brain death, history of decompressive craniectomy does not affect the result of brain perfusion scintigraphy.

Brain death and true patient care

The "brain death" standard as a criterion of death is closely associated with the need for transplantable organs from heart-beating donors. Are all of these potential donors really dead, or does the documented evidence of patients destined for organ harvesting who improve, or even recover to live normal lives, call into question the premise underlying "brain death"? The aim of this paper is to re-examine the notion of "brain death," especially its clinical test-criteria, in light of a broad framework, including medical knowledge in the field of neuro-intensive care and the traditional ethics of the medical profession. I will argue that both the empirical medical evidence and the ethics of the doctor-patient relationship point to an alternative approach toward the severely comatose patient (potential brain-dead donor). Lay Summary: Though legally accepted and widely practiced, the "brain death" standard for the determination of death has remained a controversial issue, especially in view of the occurrence of "chronic brain death" survivors. This paper critically re-evaluates the clinical test-criteria for "brain death," taking into account what is known about the neuro-critical care of severe brain injury. The medical evidence, together with the understanding of the moral role of the physician toward the patient present before him or her, indicate that an alternative approach should be offered to the deeply comatose patient.

Diagnostic Accuracy of Transcranial Doppler for Brain Death Confirmation: Systematic Review and Meta-Analysis

BACKGROUND AND PURPOSE

Transcranial Doppler is a useful ancillary test for brain death confirmation because it is safe, noninvasive, and done at the bedside. Transcranial Doppler confirms brain death by evaluating cerebral circulatory arrest. Case series studies have generally reported good correlations between transcranial Doppler confirmation of cerebral circulatory arrest and clinical confirmation of brain death. The purpose of this study is to evaluate the utility of transcranial Doppler as an ancillary test in brain death confirmation.

MATERIALS AND METHODS

We conducted a systematic review of the literature and a diagnostic test accuracy meta-analysis to compare the sensitivity and specificity of transcranial Doppler confirmation of cerebral circulatory arrest, by using clinical confirmation of brain death as the criterion standard.

RESULTS

We identified 22 eligible studies (1671 patients total), dating from 1987 to 2014. Pooled sensitivity and specificity estimates from 12 study protocols that reported data for the calculation of both values were 0.90 (95% CI, 0.87-0.92) and 0.98 (95% CI, 0.96-0.99), respectively. Between-study differences in the diagnostic performance of transcranial Doppler were found for both sensitivity (I(2) = 76%; P < .001) and specificity (I(2) = 74.3%; P < .001). The threshold effect was not significant (Spearman r = -0.173; P = .612). The area under the curve with the corresponding standard error (SE) was 0.964 ± 0.018, while index Q test ± SE was estimated at 0.910 ± 0.028.

CONCLUSIONS

The results of this meta-analysis suggest that transcranial Doppler is a highly accurate ancillary test for brain death confirmation. However, transcranial Doppler evaluates cerebral circulatory arrest rather than brain stem function, and this limitation needs to be taken into account when interpreting the results of this meta-analysis.

Transcranial Sonography and Cerebral Circulatory Arrest in Adults: A Comprehensive Review

The diagnosis of brain death remains a clinical challenge for intensive care unit physicians. Worldwide regulations in its diagnosis may differ, and the need of ancillary tests after a clinical examination is not uniform. Transcranial sonography is a noninvasive, bedside, and widely available technique that can be used in the diagnosis of the cerebral circulatory arrest that preceeds brain death. In this paper we review the general concepts, the technical requisites, the patterns of Doppler signal confirming cerebral circulatory arrest, the vessels to insonate, and the options in cases with poor acoustic window. Future research perspectives in the field of transcranial sonography are discussed as well.

Technical aids in the diagnosis of brain death: a comparison of SEP, AEP, EEG, TCD and CT angiography

BACKGROUND

The use of technical aids to confirm brain death is a controversial matter. Angiography with the intra-arterial administration of contrast medium is the international gold standard, but it is not allowed in Germany except in cases where it provides a potential mode of treatment. The currently approved tests in Germany are recordings of somatosensory evoked potentials (SSEP), brain perfusion scintigraphy, transcranial Doppler ultrasonography (TCD), and electroencephalography (EEG). CT angiography (CTA), a promising new alternative, is being increasingly used as well.

METHODS

In a prospective, single-center study that was carried out from 2008 to 2011, 71 consecutive patients in whom brain death was diagnosed on clinical grounds underwent recording of auditory evoked potentials (AEP) and SSEP as well as EEG, TCD and CTA.

RESULTS

The validity of CTA for the confirmation of brain death was 94%; the validity of the other tests was: 94% for EEG, 92% for TCD, 82% for SSEP, and 2% for AEP. In 61 of the 71 patients (86%), the EEG, TCD and CTA findings all accorded with the clinical diagnosis. The diagnosis of brain death was established beyond doubt in all patients.

CONCLUSION

In this study, the technical aids yielded discordant results in 14% of cases, necessitating interpretation by an expert examiner. The perfusion tests, in particular, can give false-positive results in patients with large cranial defects, skull fractures, or cerebrospinal fluid drainage. In such cases, electrophysiologic tests or a repeated clinical examination should be performed instead. CTA is a promising, highly reliable new method for demonstrating absent intracranial blood flow. In our view, it should be incorporated into the German guidelines for the diagnosis of brain death.

An Alternative Ultrasonographic Approach to Assess Basilar Artery Flow

Background:

Assessment of basilar artery blood flow is of interest in many neurosurgical situations. With use of ultrasonography, the standard posterior approach is difficult in neurointensive care.

Objective:

To evaluate the accuracy of an alternative submandibular approach for the assessment of blood flow in the basilar artery.

Method:

Fifty adult trauma patients without cervical spine injury were included in a prospective, comparative study. Doppler color-coded sonography of the basilar artery was performed using a 2-MHz pulsed probe. Blood flow velocities and pulsatility indexes obtained from the new submandibular approach and the standard suboccipital approach were compared.

Results:

There were no significant differences in systolic, mean, and end-diastolic velocities between both approaches. Strong relationships were found between suboccipital and submandibular approaches for systolic, mean, end-diastolic velocities, and pulsatility indexes (r2 = 0.94, 0.95, 0.95, and 0.91, respectively; P &lt; .001 for all). The mean bias between suboccipital and submandibular approaches was 1.1 cm/s for systolic velocity, 0.4 cm/s for mean velocity, −1.2 cm/s for end-diastolic velocity, and 0.0 for pulsatility index.

Conclusion:

This alternative submandibular approach appears to be accurate in measuring blood flow velocity and pulsatility index in the basilar artery. The main advantage of this approach is to facilitate monitoring of brainstem perfusion by avoiding neck flexion. This can be very helpful in intensive care settings.

The value of transcranial Doppler sonography with a transorbital approach in the confirmation of cerebral circulatory arrest

OBJECTIVE

Transcranial Doppler sonography (TCD) provides accurate confirmation of cerebral circulatory arrest (CCA) in brain death (BD), but is not feasible in patients with absent temporal bone windows. We added the transorbital approach in the TCD protocol for the diagnosis of CCA and compared findings with angiography. Furthermore, we evaluated whether reporting the angiographic and sonographic confirmation of CCA to relatives of brain-dead patients improves their comprehension and satisfaction with the medical information.

PATIENTS AND METHODS

Eighty-two clinically brain-dead patients underwent 4-vessel angiography, TCD of the basilar and middle cerebral arteries, and transorbital Doppler sonography (TOD) of the internal carotid arteries. Relatives were randomly allocated to 41 in whom BD was presented as a clinical diagnosis (group A) and to 41 in whom BD was presented as a clinical diagnosis confirmed by TCD and angiography (group B). Comprehension and satisfaction of the relatives were assessed using an interview and a questionnaire.

RESULTS

Both angiography and TCD verified CCA in all cases (k = 1). In 11 patients with failure of the transtemporal approach, CCA was confirmed by the transorbital recordings. The addition of TOD enabled 15.5% more cases of CCA to be diagnosed by TCD. Group B exhibited improved comprehension and satisfaction rates (P < .05).

CONCLUSIONS

The addition of TOD increases the efficacy of TCD in confirming CCA in BD. Reporting confirmation of CCA to families of brain-dead patients may improve their comprehension and satisfaction with the provided medical information.

The relevance of early TCD monitoring in the intensive care units for the confirming of brain death diagnosis

Brain death (BD) diagnosis is the clinical assessment of the irreversible loss of function of the entire brain, including the brainstem. Transcranial Doppler (TCD) examination is used in several countries as a confirmatory test to assess cerebral circulatory arrest (CCA). A total of 1,400 TCD examinations were performed in 623 patients (pts) admitted to intensive care units (ICUs) of our hospital during the last 6 years. Oscillating flow, systolic spikes and the absence of any TCD signal were considered as diagnostic patterns of irreversible CCA. TCD patterns of CCA were detected in 56 pts. In 25 pts, deeply sedated with barbiturate therapy, TCD was employed as confirmatory test for BD diagnosis and 14 of them could become organ and/or tissue donors. TCD is a safe and inexpensive tool that can be performed at the bedside, and it allows to shorten the diagnostic process of BD, which is the prerequisite for organ donation.

Assessing Circle of Willis blood circulation in dogs with transcranial color-coded duplex sonography

Insonation of Circle of Willis by transcranial Doppler duplex color sonography is described in 30 healthy dogs with 15 weighing < 33 lb and 15 weighing >33 lb. Imaging was via a temporal window to explore the rostral, middle, and caudal cerebral arteries on both the left and right-hand sides; and through an suboccipital window to study the basilar artery. Normal mean values of the peak systolic velocity (PSV), end diastolic velocity, mean velocity, resistance index (RI), and pulsatility index (PI) were characterized and compared with those obtained in previous studies. There was significant differences in the PSV, RI, and PI in the rostral cerebral artery between dogs weighing < 33 vs. > 33 lb. Mean PSV was higher in weighing over 33 lb, whereas the mean resistive index and mean PI were lower in these dogs.

CT angiography for brain death diagnosis

BACKGROUND AND PURPOSE

Lack of cerebral circulation is an important confirmatory test for brain death (BD). Conventional angiography remains the standard imaging method, but CT angiography (CTA) is emerging as an alternative. France accepts BD diagnoses relying on a score based on lack of opacification of 7 intracerebral vessels in CTA images. The purpose of this study was to validate the efficiency of this score and to evaluate the sensitivity of a novel 4-point CTA score in confirming BD.

MATERIALS AND METHODS

A prospective multicentric study was conducted during 12 months with 105 patients referred for CTA to confirm a clinical diagnosis of BD. Clinical data were recorded. CTA images were interpreted first by local radiologists at the referent center, resulting in a 7-point score based on lack of opacification of the pericallosal and cortical segments of the middle cerebral arteries (MCAs), internal cerebral veins (ICVs), and 1 great cerebral vein per patient and, second, by a consensus panel of 3 expert radiologists, blinded to the initial scores, resulting in novel 4-point scores based on the lack of opacification of the cortical segments of the MCAs and ICVs.

RESULTS

Injection of contrast medium did not alter renal function. With the initial 7-point score, sensitivity was 62.8%. With the simplified 4-point score, sensitivity was 85.7% and specificity was 100%. Opacification of ICVs was absent in 98.1% of patients.

CONCLUSIONS

Lack of opacification in the cortical segments of the MCAs and internal veins in CTA is efficient and reliable for confirming BD.

Benefits of combination of electroencephalography, short latency somatosensory evoked potentials, and transcranial Doppler techniques for confirming brain death

OBJECTIVE

Optimization of combining electroencephalography (EEG), short latency somatosensory evoked potentials (SLSEP) and transcranial Doppler (TCD) techniques to diagnose brain death.

METHODS

One hundred and eleven patients (69 males, 42 females) from the major hospitals of Zhejiang Province were examined with portable EEG, SLSEP and TCD devices. Re-examinations occurred < or =12 h later.

RESULTS

The first examination revealed that the combination of SLSEP and EEG led to more sensitive diagnoses than the combination of SLSEP and TCD. Re-examination confirmed this and also revealed that the combination of TCD and EEG was the most sensitive.

CONCLUSION

The results show that using multiple techniques to diagnose brain death is superior to using single method, and that the combination of SLSEP and EEG is better than other combinations.

Transcranial Doppler ultrasonography in the assessment of cerebral circulation arrest: improving sensitivity by transcervical and transorbital carotid insonation and serial examinations

INTRODUCTION

Transcranial Doppler (TCD) can detect the cerebral circulation arrest (CCA) in brain death. TCD is highly specific, but less sensitive because of false-negatives accounting for up to 10%. The aim of the study was to explore the diagnostic accuracy of TCD and to determine whether it can be augmented by strategies such as the insonation of the extracranial internal carotid artery (ICA) and sequential examinations.

METHODS

Data of 184 patients, who met clinical criteria of brain death, observed from 1998 through 2006, were retrospectively reviewed. The study of cerebral arteries was performed through the transtemporal approach, suboccipital insonation of the vertebro-basilar system, transorbital insonation of the ICA and ophthalmic artery, and transcervical insonation of the extracranial ICA. Repeated exams were performed in cases of persistent diastolic flow.

RESULTS

The specificity of the testing was 100%, no false-positive cases were recorded. The sensitivity of conventional TCD examination was 82.1%. The insonation of the extracranial ICA increased sensitivity to 88% allowing the detection of CCA in those patients lacking temporal windows; serial examinations further increased sensitivity to 95.6%.

CONCLUSIONS

The addition of insonation of the cervical ICA and of the siphon increased sensitivity of TCD. Nevertheless, a CCA flow patterns may appear later on those segments. Serial examinations, may be needed in those cases.

Limitations of computed tomographic angiography in the diagnosis of brain death

OBJECTIVE

To evaluate the accuracy of cerebral computed tomographic angiography (CT-a) for the diagnosis of brain death (BD).

DESIGN AND SETTING

Prospective observational study in intensive care units.

PATIENTS

Twenty-one clinically BD patients enrolled over 12 months.

MEASUREMENTS AND RESULTS

All clinically BD patients were evaluated by electroencephalography (EEG) and CT-a after exclusion of hypothermia and drug intoxication. Data collected included: demographic characteristics, cause of BD, delay between in-hospital admission and BD diagnosis and between EEG and CT-a, occurrence of cardiac arrest, administration of vasoactive agents, results of EEG and CT-a. We evaluated the sensitivity of EEG and CT-a and their agreement. Groups were compared according to BD diagnosis by EEG and CT-a (E+C+), or only by EEG (E+C(-)). Statistical analysis were performed by Mann-Whitney test and Fisher's exact test. BD was confirmed by EEG in all cases (sensitivity 100%) whereas only 11 patients of 21 had no cerebral perfusion during CT-a (sensitivity 52.4%). No agreement was documented between EEG and CT-a for the diagnosis of BD (kappa = 0). Patients' characteristics did not differ between E+C+ and E+C(-) groups. In the E+C(-) group arterial opacification was observed in 100% of patients, but opacification of the internal cerebral veins was achieved in only 30%.

CONCLUSIONS

In clinically BD patients with no electroencephalographic activity CT-a documents opacification of the intracerebral vessels in a significant percentage of the cases. Therefore CT-a cannot be recommended as a means of BD diagnosis.

Comparison between transcranial color Doppler ultrasonography and angiography in the confirmation of brain death

OBJECTIVE

Cerebral blood flow tests have increasingly been advocated for the confirmation of brain death (BD). Angiography has been considered the gold standard in the diagnosis of BD but is invasive. We validated transcranial color Doppler ultrasonography (TCD) to confirm BD by comparing it to angiography.

PATIENTS AND METHODS

Forty patients experienced the clinical diagnosis of brain death due to head injury in 19 cases (47.5%), cerebral hemorrhage in 11 (27.5%), subarachnoid hemorrhage in 7 (17.5%), and cerebral infarction in 3 (7.5%). Blood pressure, heart rate, SPO2, and PCO2 were monitored throughout the study. Patients were excluded if episodes of hypoxia, arrhythmia, and hypotension occurred during examinations, or if the TCD was not technically feasible.

RESULTS

Both angiography and TCD confirmed BD in all patients. The agreement between the above methods to confirm BD was 100%. Angiography showed the absence of filling of intracranial arteries, while TCD revealed: (1) brief systolic forward flow or systolic spikes and diastolic reversed flow (50%); (2) brief systolic forward flow or systolic spikes and no diastolic flow (25%); (3) no demonstrable flow in a patient in whom flow had been clearly documented on a previous TCD examination (12.5%). Five patients required repeated TCD examinations, because of initial detection of a diastolic to-and-fro flow pattern. BD was confirmed by TCD in the above patients after 30 hours of clinical BD.

CONCLUSION

TCD was a sensitive tool to diagnose BD, affording a reliable alternative examination to standard angiography.