Applications of Transcranial Color-Coded Sonography in the Emergency Department

Using DFT on ultrasound measurements to determine patient-specific blood flow boundary conditions for computational hemodynamics of intracranial aneurysms

Boundary conditions (BCs) is one pivotal factor influencing the accuracy of hemodynamic predictions on intracranial aneurysms (IAs) using computational fluid dynamics (CFD) modeling. Unfortunately, a standard procedure to secure accurate BCs for hemodynamic modeling does not exist. To bridge such a knowledge gap, two representative patient-specific IA models (Case-I and Case-II) were reconstructed and their blood flow velocity waveforms in the internal carotid artery (ICA) were measured by ultrasonic techniques and modeled by discrete Fourier transform (DFT). Then, numerical investigations were conducted to explore the appropriate number of samples (N) for DFT modeling to secure the accurate BC by comparing a series of hemodynamic parameters using in-vitro validated CFD modeling. Subsequently, a comprehensive comparison in hemodynamic characteristics under patient-specific BCs and a generalized BC based on a one-dimensional (1D) model was conducted to reinforce the understanding that a patient-specific BC is pivotal for accurate hemodynamic risk evaluations on IA pathophysiology. In addition, the influence of the variance of heart rate/cardiac pulsatile period on hemodynamic characteristics in IA models was studied preliminarily. The results showed that N ≥ 16 for DFT model is a decent choice to secure the proper BC profile to calculate time-averaged hemodynamic parameters, while more data points such as N ≥ 36 can ensure the accuracy of instantaneous hemodynamic predictions. In addition, results revealed the generalized BC could overestimate or underestimate the hemodynamic risks on IAs significantly; thus, patient-specific BCs are highly recommended for hemodynamic modeling for IA risk evaluation. Furthermore, this study discovered the variance of heart rate has rare influences on hemodynamic characteristics in both instantaneous and time-averaged parameters under the assumption of an identical blood flow rate.

Concurrent subarachnoid haemorrhage and internal carotid artery dissection: a transcranial colour-coded sonography diagnosis

We report the case of a young woman affected by an aneurysmal subarachnoid haemorrhage (SAH) and numerous anatomic abnormalities. A Transcranial Colour-Coded Duplex Sonography, performed with the aim of monitoring the vasospasm, showed a non-pulsatile flow with loss of sharp systolic peak and lowering of mean flow velocities in the right extracranial Internal Carotid Artery (ICA) and all its intra-cranial branches. This event suggested a possible concomitant acute right ICA sub-occlusion with a lack of collateral circulation. This type of flow is typically found in systemic and brain arteries of patients undergoing to venous-arterial extracorporeal membrane oxygenation or to left ventricular assist devices. The absence of an adequate cerebral collateral circulation might be the explanation for this type of atypical flow. Aneurysms and arterial dissections contribute to SAH and ischemic stroke events, leading to long-term physical and cognitive disability. In our case, the prompt neurosonological diagnosis leaded to patient's good outcome.

Noninvasive evaluation of intracranial pressure in patients with traumatic brain injury by transcranial Doppler ultrasound

INTRODUCTION

The purpose of this study was to investigate the relationship between pulsatility index (PI) or optic nerve sheath diameter (ONSD) and intracranial pressure (ICP) in patients with traumatic brain injury (TBI), and the ability of ONSD and ICP to predict intracranial hypertension.

METHODS

A total of 68 patients with TBI were included in this retrospective study. After receiving surgery treatment, they underwent transcranial Doppler ultrasound (TCD). The statistical correlation between PI or ONSD and ICP 1 week after surgery was analyzed. Furthermore, the areas under the curve (AUCs) of ONSD or PI or a combination of them were calculated to predict intracranial hypertension.

RESULTS

There was a correlation between ONSD and ICP. This correlation still remained at ONSD ≥ 5 mm. Furthermore, there was a strong correlation between PI and ICP. There was a moderate correlation between ICP and PI on days 3, 4, and 5 after surgery (r = 0.508, p < .001), and a strong correlation on days 6 and 7 after surgery (r = 0.645, p < .001). Moreover, for predicting intracranial hypertension with PI ≥ 1.2 mm or ONSD ≥ 5 mm or a combination of them, the AUC was 0.729, 0.900, and 0.943, respectively (p < .001).

CONCLUSIONS

The correlation between ONSD or PI and invasive ICP was different with different levels of ICP in different periods in patients with TBI after surgery. When ONSD ≥ 5 mm and PI ≥ 1.2, it could predict elevated ICP more accurately.

Multiorgan Point-of-Care Ultrasound in a Patient With Coronavirus Disease 2019 Pneumonia Complicated by Subarachnoid Hemorrhage and Pulmonary Embolism

Morbidity and mortality associated with the pandemic severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) disease (coronavirus disease 2019 [COVID-19]) are not only due to acute respiratory distress syndrome but also related to multiorgan involvement and dysfunction. In this report, we present a critically ill patient with severe COVID-19 pneumonia, during which he required extracorporeal membrane oxygenation and suffered from multiple complications. Bedside sonography became an important tool to manage the patient by adapting artificial ventilation parameters and played a key role in the diagnosis of thrombotic events and the monitoring of subarachnoid hemorrhage that unexpectedly complicated the case.

Surface Point Cloud Ultrasound with Transcranial Doppler: Coregistration of Surface Point Cloud Ultrasound with Magnetic Resonance Angiography for Improved Reproducibility, Visualization, and Navigation in Transcranial Doppler Ultrasound

Transcranial Doppler (TCD) ultrasound is a standard tool used in the setting of recent sub-arachnoid hemorrhage (SAH). By tracking velocity in the circle-of-Willis vessels, vasospasm can be detected as interval velocity increase. For this disease process, repeated TCD velocity measurements over many days is the basis for its usefulness. However, a key limitation to TCD is its user dependence, which is itself largely due to the fact that exact information about probe positioning is lost between subsequent scans. Surface point cloud ultrasound (SPC-US) was recently introduced as a general approach combining ultrasound and three-dimensional surface imaging of patient + probe. In the present proof-of-principle demonstration, we have applied SPC-US to TCD and co-registered the skin surface with that from MRA images to provide a roadmap of the vasculature in 3D space for better speed, accuracy, reproducibility, and potential semi-automation of TCD. Collating the acronyms, we call the combined approach SPC-US-TCD. TCD of the M1 was obtained while three-dimensional photographic images were obtained with the Structure Sensor camera. MRA imaging was also obtained. SPC-US-TCD and corresponding MRA 3D reconstruction images were co-registered in MeshMixer using the skin surfaces for alignment. A cylinder the width of the TCD probe was placed over the fused images and aligned with the direction and orientation of the TCD probe to demonstrate the acoustic beam. In the fused images, the acoustic beam intersects the right M1 segment of the middle cerebral artery (MCA). The angle of insonation is well demonstrated and measurable in various planes. Distance measurements made in Blender localized the TCD probe position based on three skin surface landmarks, and tabulated orientation based on three angles along the corresponding directions. SPC-US-TCD provides valuable information that is otherwise not present in TCD studies. By co-registering SPC-US-TCD data with that from cross sectional vessel imaging, precise probe location relative to external skin surface landmarks as well as 3D vessel location relative to TCD probe placement offers the potential to provide a roadmap that improves exam reproducibility, speed of acquisition, and accuracy. The goal of future work is to demonstrate this improvement statistically by application to multiple patients and scans.

Clinical Applications of Ultrasonography in Neurocritically Ill Patients

Ultrasonography is part of the multimodal monitoring of the neurocritical patient. Through transcranial color Doppler ultrasound, carotid-color Doppler ultrasound, and ocular ultrasound it is possible to diagnose and monitor a multitude of pathological conditions, such as cerebrovascular events, vasospasm, Terson syndrome, carotid atheromatosis, and brain death. Furthermore, these techniques enable the monitoring of the intracranial pressure, the cerebral perfusion pressure, and the midline deviation, which allows us to understand the patient's neurocritical pathology at their bedside, in a noninvasive way. Although none of these tools have yet been shown to improve patient prognosis, the dissemination of knowledge and management of neurovascular ultrasonography could significantly improve the comprehensive management of neurocritical patients.

Transcranial Doppler Can Predict Development and Outcome of Sepsis-Associated Encephalopathy in Pediatrics With Severe Sepsis or Septic Shock

Background and Aim: Sepsis is a common cause of pediatric intensive care unit (ICU) admission. Sepsis-associated encephalopathy (SAE) may occur owing to brain dysfunction in those patients and may be related to impaired cerebral microcirculation. Transcranial Doppler (TCD) can be used to detect this impairment. In this study, we aimed to assess the role of TCD in prediction of SAE and mortality in patients with severe sepsis or septic shock admitted to PICU. Patients and Methods: This prospective study included 75 children admitted to PICU owing to severe sepsis or septic shock. Upon admission, all patients were subjected to careful history taking, thorough clinical examination, and standard laboratory workup. Severity of clinical illness was assessed using the Pediatric Risk of Mortality (PRISM) III score. TCD was performed on the first day of admission after the normalization of systolic blood pressure with or without vasopressors. The primary study outcome was differences in the measurement of TCD in SAE, and the secondary outcome was discharge from ICU or mortality. Results: The study comprised 45 children with SAE and 30 age- and sex-matched children without SAE. In this study, SAE patients had significantly higher pulsatility index [PI; median interquartile range (IQR): 1.15 (0.98-1.48) vs. 1.0 (0.95-1.06), p = 0.002] and resistive index [RI; median (IQR): 0.68 (0.61-0.77) vs. 0.62 (0.59-0.64), p = 0.001] than had non-SAE patients. PI and RI showed good performance as predictors of subsequent SAE development [area under the curve (AUC): 0.72 and 0.73, respectively]. Non-survivors in SAE patients had significantly higher PRISM III. Receiver operating characteristic (ROC) curve analysis showed good performance of PI and RI as predictors of mortality at the end of follow-up. Conclusions: In children with SAE, cerebrovascular resistance is high and is associated with increased mortality.

Transcranial Doppler ultrasound in neurocritical care

Multimodality monitoring is a common practice in caring for neurocritically ill patients, and consists mainly in clinical assessment, intracranial pressure monitoring and using several imaging methods. Of these imaging methods, transcranial Doppler (TCD) is an interesting tool that provides a non-invasive, portable and radiation-free way to assess cerebral circulation and diagnose and follow-up (duplex method) intracranial mass-occupying lesions, such as hematomas and midline shift. This article reviews the basics of TCD applied to neurocritical care patients, offering a rationale for its use as well as tips for practitioners.