Researchers at the Intensive Care Unit of Hospital Metropolitano Doutor Célio de Castro retrospectively analyzed 178 adult patients who completed brain death protocols between December 2017 and December 2023. Of these, 141 patients underwent transcranial Doppler ultrasonography, or TCD, as the complementary exam, while 37 were evaluated with electroencephalography or cerebral angiography. The findings, published in the journal Neurocritical Care, show that TCD use was independently associated with a 53.9 percent reduction in the median time needed to complete the brain death protocol, a difference so large that it reshapes the logistics of end-of-life care and organ procurement.

The numbers are striking. In the TCD group, the median protocol duration was nine hours, with an interquartile range of five to twenty-three hours. In the non-TCD group, the median stretched to thirty-five hours, with an interquartile range of twenty to sixty-six hours. After adjusting for age, sex, comorbidity burden measured by the Charlson Comorbidity Index, illness severity measured by the Simplified Acute Physiology Score III, calendar year, and whether the protocol was opened during business hours or after hours, TCD use carried an incidence rate ratio of 0.46, meaning the protocol took less than half as long. The only other independent predictor of protocol duration was whether the process began during business hours, underscoring how staffing availability shapes this delicate timeline.

Transcranial Doppler ultrasonography is a bedside technique that uses low-frequency ultrasound pulses through the temporal bone and other acoustic windows to measure blood flow velocity in the major arteries of the circle of Willis, including the middle cerebral, anterior cerebral, and basilar arteries. The technique was first described in 1982, when researchers demonstrated that flow velocity in the basal cerebral arteries could be recorded noninvasively. In the context of brain death, rising intracranial pressure progressively exceeds the perfusion pressure, producing a characteristic sequence of Doppler waveforms: first a blunting of diastolic flow, then oscillating or reverberating flow in which blood moves back and forth with each heartbeat without net forward perfusion, then tiny systolic contraction spikes, and finally the disappearance of detectable flow altogether. Demonstration of these arrest patterns in both anterior and posterior circulations, on two examinations separated by an interval defined by national guidelines, provides evidence of cerebral circulatory arrest.

The diagnostic credentials of the technique are well established. A meta-analysis published in Intensive Care Medicine in 2006 reported high specificity for confirming brain death, and a subsequent systematic review and meta-analysis in the American Journal of Neuroradiology reached similar conclusions, with reported sensitivity around 88 percent and specificity approaching 98 percent in pooled analyses. Brazilian guidelines issued in 2012 formally endorsed transcranial ultrasound as a confirmatory test for brain death, and the country’s Federal Council of Medicine incorporated it into the regulatory framework through Resolution 2,173 of 2017. Unlike angiography, TCD requires no transport to a radiology suite, no iodinated contrast, and no exposure of potentially donor organs to nephrotoxic agents. Unlike electroencephalography, it does not require prolonged recording sessions or interpretation delays, and it sidesteps the technical confounders of electrical artifacts in the intensive care environment.

The efficiency gains extended beyond the protocol itself. Length of stay in the intensive care unit after protocol initiation was significantly shorter in the TCD group, with a median of one day compared with two days in the non-TCD group, and an adjusted incidence rate ratio of 0.51. In a health system where intensive care beds are chronically scarce and expensive, each day of occupancy by a patient who has already died by neurologic criteria carries an opportunity cost measured in the patients waiting for that bed. The researchers also examined whether the choice of confirmatory exam influenced organ donation, and found that it did not: donation rates were statistically indistinguishable between the groups, at 35 percent in the TCD group and 38 percent in the non-TCD group. Faster protocols, in other words, did not come at the expense of donation outcomes, though they also did not visibly increase them in this cohort.

The study’s statistical approach was deliberately conservative. Because protocol duration and length of stay are skewed, count-like variables, the team used negative binomial regression rather than ordinary linear models, adjusting for the full panel of demographic, clinical, and logistical covariates. The groups were comparable at baseline in age, comorbidity, severity scores, and sex, with all baseline comparisons showing no significant differences. Supplementary correlation analyses reinforced the main findings: TCD use and business-hours protocol opening showed the strongest negative correlations with protocol duration, while illness severity, age, and comorbidity played smaller or negligible roles. Notably, the underlying diagnoses differed between groups, with subarachnoid hemorrhage more frequent among patients who did not receive TCD, at 49 percent versus 26 percent, and ischemic stroke more frequent in the TCD group, at 28 percent versus 11 percent. This pattern likely reflects a practical reality of neurosonology: adequate acoustic windows are harder to obtain in some patients, and certain clinical scenarios push teams toward angiography or electroencephalography instead.

The authors are careful about the limits of their conclusions. This was a single-center, retrospective study at a Brazilian tertiary hospital where confirmatory testing is mandatory, and they caution that generalizability to settings without such requirements is limited. In countries where confirmatory tests are optional, the operational calculus differs, since the protocol can sometimes be completed with repeated clinical examinations alone. The findings also hinge on the availability of trained practitioners; TCD interpretation in the setting of suspected brain death demands specific expertise in recognizing the arrest waveforms and in distinguishing them from technical limitations such as poor insonation windows. The authors argue that their results support broader implementation of TCD in countries with mandatory confirmatory testing, contingent on that trained practitioner availability being secured.

The implications ripple outward to two of the most pressing issues in critical care. The first is organ donation, where every hour of delay increases the risk of hemodynamic instability, cardiac arrest, and loss of viable organs, and where families awaiting a definitive answer endure prolonged uncertainty at the bedside. The second is intensive care capacity, where protocols that conclude in nine hours rather than thirty-five return beds to the queue of critically ill patients faster. A bedside ultrasound exam that costs a fraction of a digital subtraction angiography study and requires no patient transport may thus be one of the highest-leverage tools available in the delicate interval between devastating brain injury and the formal pronouncement of death. As brain death determination frameworks worldwide undergo revision, including the recent consensus guideline from American neurologic and critical care societies, this Brazilian dataset offers a reminder that the operational details of how death is confirmed can matter almost as much as the criteria themselves.

Subject of Research: Use of transcranial Doppler ultrasonography as a confirmatory exam in brain death determination protocols

Article Title: Transcranial Doppler Ultrasonography as a Complementary Exam in Brain Death Determination: Impact on Protocol Duration and ICU Length of Stay—A Single-Center Study in Brazil

Article References: de Freitas, M. R., de Lima, A. F., & Coutinho, C. F. A. (2026). Transcranial Doppler Ultrasonography as a Complementary Exam in Brain Death Determination: Impact on Protocol Duration and ICU Length of Stay—A Single-Center Study in Brazil. Neurocritical Care. https://doi.org/10.1007/s12028-026-02641-w

Image Credits: AI Generated

DOI: 10.1007/s12028-026-02641-w

Keywords: transcranial Doppler, brain death, brain death protocol, organ donation, intensive care unit, cerebral circulatory arrest, neurocritical care, TCD ultrasonography, ICU length of stay, Brazil, confirmatory testing, negative binomial regression

For decades, securing an airway in neonates has relied heavily on conventional methods such as capnography and chest X-rays, which carry inherent limitations. Capnography, while useful, may give false negatives in cases of cardiac arrest or low pulmonary blood flow, and chest radiographs, although defining anatomical tube depth, expose fragile infants to ionizing radiation and delay confirmation. The adoption of real-time tracheal ultrasound as a bedside, radiation-free diagnostic modality offers a compelling alternative, marrying immediacy of results with precision, thereby streamlining critical neonatal resuscitation and ventilation.

Ultrasonography leverages sound waves to delineate soft tissues in real time, allowing clinicians to visualize the endotracheal tube as it traverses the trachea. This technique stands apart from static radiology by furnishing dynamic imaging during the intubation process itself, enhancing the chances of immediate correction if misplacement occurs. The data synthesized through this meta-analysis elucidate the high sensitivity and specificity of tracheal ultrasound, underscoring its reliability and potential to supplant traditional confirmation tools, especially in resource-limited or time-sensitive settings.

The meta-analytic approach meticulously aggregated diagnostic accuracy data from studies executed across diverse neonatal acute care environments, spanning tertiary neonatal intensive care units (NICUs) to emergency delivery wards. The robustness of their inclusion criteria ensured only high-caliber prospective investigations and cross-sectional studies were incorporated, safeguarding the analytical power of the outcome measures. Such stringent study selection amplifies the confidence clinicians can place in these findings when considering the integration of POCUS into their neonatal airway management protocols.

Among the key revelations is the near-perfect concordance rate between ultrasound findings and standard confirmatory modalities, with sensitivity rates approaching 98% and specificity not far behind. These statistically compelling figures translate directly to enhanced clinical decision-making, minimizing catastrophic consequences such as esophageal intubation or accidental bronchial intubation. Equally important, the swift availability of ultrasound confirmation truncates the window during which hypoxia or ventilation failure might jeopardize neonates who are intrinsically vulnerable given their underdeveloped respiratory systems.

Technological advancements have also refined the ultrasound equipment and probes tailored specifically for neonatal anatomy, optimizing image resolution while adhering to safety parameters. Portable machines equipped with high-frequency linear transducers facilitate succinct imaging of the fetal neck and tracheal structures without undue neonatal handling or repositioning, reducing procedural stress. The ease of sterilization and cost-effectiveness further bolster the feasibility of widespread adoption, making this tool an attractive asset for NICUs globally.

Operator skill remains a pivotal determinant in successful ultrasound application; however, the meta-analysis highlights encouraging trends wherein brief yet focused training sessions substantially elevate clinician competency. Interactive, hands-on workshops combined with virtual simulation platforms foster acquisition of proficiency, greatly diminishing the learning curve traditionally seen with novel diagnostic modalities. This scalability of training promises to democratize access to this lifesaving tool, ensuring equitable patient care irrespective of geographic or socioeconomic barriers.

Furthermore, the ultrasonographic protocol for ETT confirmation integrates seamlessly with existing neonatal resuscitation algorithms. The non-invasive nature of the process means it does not interfere with concurrent ventilatory support or other critical interventions, preserving the integrity of care continuity. From a workflow standpoint, embedding POCUS empowers multidisciplinary teams to expedite the verification process, facilitating prompt corrections and thereby improving neonatal stabilization metrics.

The safety profile of tracheal ultrasonography is exceptionally favorable, devoid of radiation exposure risks and yielding no documented adverse effects on neonatal physiology in the analyzed studies. This characteristic is of paramount importance given neonates’ heightened sensitivity to radiation-induced injury and the ethical imperative to minimize any iatrogenic harm. The opportunity to employ a technique that is gentle yet decisively informative aligns with contemporary principles of minimally invasive neonatal care.

Equally promising is the potential for ultrasonographic methods to transcend ETT confirmation alone. Emerging research avenues suggest the modality could assist in guiding intubation procedures, estimating endotracheal tube depth, and even detecting pulmonary pathologies early during admission. The dynamic visualization capacity uniquely positions ultrasound as a multifaceted instrument in neonatal airway and pulmonary management, heralding a future of integrative point-of-care diagnostics that optimize individualized treatment regimens.

Despite the laudable gains, the meta-analysis prudently acknowledges residual challenges, notably heterogeneity in ultrasound protocols across studies and variability in reporting standards. Future investigations are poised to refine standardized imaging guidelines, establish consensus training curricula, and elucidate cost-benefit analyses to anchor policy shifts. Further innovation in probe miniaturization and image processing algorithms may enhance diagnostic clarity, particularly in micropreterm infants with delicate anatomical landmarks.

From a global health perspective, the embrace of POCUS for neonatal airway confirmation embodies a paradigm shift toward safer, faster, and more equitable care. In under-resourced regions where access to radiography is scant and expertise is limited, ultrasound presents a viable, scalable solution that can curtail neonatal mortality related to airway mismanagement. International collaborations and funding mechanisms aligned with neonatal mission priorities are likely to accelerate dissemination and impact.

This systematic review and meta-analysis collectively signify a watershed moment in neonatal critical care diagnostics. As compelling evidence accrues validating the efficacy, reliability, and multifaceted utility of real-time tracheal ultrasonography, clinical practice stands on the cusp of transformation. The integration of this technology promises enhanced neonatal survival, decreased procedural complications, and improved quality of life outcomes—a quantum leap in the mission to safeguard the most fragile lives.

In conclusion, the alliance of technological innovation with clinical urgency encapsulated in this research offers a beacon of hope for neonatologists worldwide. Real-time point-of-care tracheal ultrasonography has emerged not merely as a diagnostic adjunct, but as a potential gold standard for confirming endotracheal tube placement in neonates. Through continued research, education, and infrastructural investment, this promising modality will indelibly reshape neonatal airway management and elevate standards of critical care in neonatal units across the globe.

Subject of Research: Diagnostic accuracy of real-time point-of-care tracheal ultrasonography for confirming proper endotracheal tube placement in neonatal acute care settings.

Article Title: Diagnostic accuracy of real‑time point-of-care tracheal ultrasonography for the confirmation of proper endotracheal tube placement in neonatal acute care settings: a systematic review and diagnostic test accuracy meta-analysis.

Article References:
Alsabri, M., Abady, E., Hasan, M.T. et al. Diagnostic accuracy of real‑time point-of-care tracheal ultrasonography for the confirmation of proper endotracheal tube placement in neonatal acute care settings: a systematic review and diagnostic test accuracy meta-analysis. J Perinatol (2025). https://doi.org/10.1038/s41372-025-02461-4

Image Credits: AI Generated

DOI: 19 November 2025