Assessment of brain midline shift using sonography in neurosurgical ICU patients

Point-of-Care-Ultrasound in Pediatrics: A Review and Update

Point-of-Care-Ultrasound (POCUS) has encountered a tremendous expansion in patient care. POCUS has taken a central role during invasive procedures. POCUS has expanded to most subspecialties from adult to pediatric and neonatal health care. POCUS in pediatrics has also become part of specific critical situations such as myocardial function assessment during cardiac arrest, extracorporeal membrane oxygenation deployment and neurological evaluation. In this review we will go over the most important historical aspects of POCUS. We will also review important aspects of POCUS in the intensive care unit, cardiologist evaluation and in the emergency department among others.

Application of Transcranial Sonography for the Assessment of Brain Midline Shift in Patients Presenting With Suspected Intracranial Pathology to the Emergency Department of a Tertiary Care Hospital in Central Gujarat, India

BACKGROUND

A shift in midline brain structure indicates raised intracranial pressure (ICP), thereby a sign of compromised perfusion to brain tissues or a mass effect. Early diagnosis can help in planning timely neurosurgical interventions that could prevent further neuron loss. Also, this may aid in neuroprognostication.

OBJECTIVES

The objectives of the study were to find the accuracy of bedside assessment of brain midline shift (MLS) using transcranial sonography (TCS) in comparison to a computed tomography (CT) scan of the brain for patients presenting with suspected intracranial pathology to the emergency department (ED).

METHODS

This prospective observational study was carried out for one year in an ED. A total of 124 patients with suspected intracranial pathology were included in the study. Transtemporal scanning along the orbitomeatal line was performed to image the third ventricle. The distance between the third ventricle and the internal side of the temporal bone was measured on both sides as A and B. The MLS was then calculated using the following formula: midline shift = (A-B)/2. The data were entered and analyzed using a Microsoft Excel worksheet (Microsoft Corp., Redmond, WA).

RESULTS

Out of the total 124 patients enrolled in this study, adequate views for 12 patients were not obtained and, hence, they were excluded from the study. The time to perform a TCS assessment of brain MLS was around 22 minutes (range: 15-30 minutes). In our study, out of 112 analyzed patients, 33 (29.5% of our study) had a significant MLS in the brain (defined by an MLS of more than 5 mm) diagnosed by TCS. Analyzing CT brain results revealed that out of the total 112 patients under study, 27 had a significant brain MLS (24.1% of the total population under study) as defined above.

CONCLUSION

A TCS is a promising alternative to a brain CT in an emergency for brain MLS detection.

Assessment of Midline Shift in Postdecompressive Craniectomy Patients in Neurocritical Care: Comparison between Transcranial Ultrasonography and Computerized Tomography

Background

Monitoring and evaluation of intracranial structures remain a fundamental element in the neurointensive care unit. Most used technique to monitor progression is the use of computed tomography (CT) in intracranial hemorrhage (ICH) or stroke. Rapid assessment of brain pathology can be made using CT to analyze the midline shift (MLS), hematoma expansion, and ventricular size, but transferring a patient who is intubated is time and resource-consuming task. Ultrasonography is a noninvasive technique, portable, and has the possibility of fast interpretation.

Aims and Objectives

To measure the brain MLS in decompressive craniectomy patients using transcranial ultrasonography (TCS) and compare the correlation of these results with CT scan measurements of MLS in the same patient.

Materials and Methods

Patients who have undergone decompressive craniectomy due to various reasons like ICH, traumatic brain injury, etc., and have a MLS. Trans cranial ultrasonography was assessed by a single consultant (Neuro Critical Care Intensivist) who was blinded for the CT scan measurement. CT scan measurement of MLS was assessed by a neuroradiologist using standard guidelines, who was blinded for the TCS results of MLS. The finding of a MLS >0.5 cm in the CT scan was considered a significant MLS.

Results

A total of 31 patients were recruited for the study. MLS measured using CT was 0.91 ± 0.67 cm. MLS via TCS was 0.91 ± 0.66 cm. A significant MLS via TCS was found in 77.4%. Intraclass correlation coefficient (ICC) was calculated between CT-MLS and TCS MLS and obtained the value of ICC as 0.996, indicating an almost perfect agreement.

Conclusion

Patients after decompressive craniectomy may present as an ideal candidate to visualize intracerebral anatomy with a high resolution. TCS might be considered as an alternative to CT to measure MLS in decompressive craniectomy patients.

Assessment of cerebral blood flow velocities, brain midline shift and optic nerve sheath diameter by ultrasound in patients undergoing elective craniotomy: A prospective observational feasibility study

BACKGROUND

Brain ultrasound allows measuring the cerebral flow velocity, brain midline shift and optic nerve sheath diameter. Literature is scarce in determining the feasibility to perioperatively perform these measurements altogether and the cerebrovascular behavior in patients scheduled for elective craniotomy.

METHODS

We assessed bilateral cerebral flow velocities, composite index, brain midline shift and optic nerve sheath diameter by cerebral ultrasound in patients scheduled for elective craniotomy before anesthetic induction, at extubation, and at 6 and 24 h after. The aim was to assess the feasibility of brain ultrasound in patients for elective craniotomy and to describe the changes in cerebral flow velocities, brain midline shift and optic nerve sheath diameter from baseline values at different times in the postoperative period.

RESULTS

Sixteen patients were included, of these two were excluded from analysis due to an inadequate sonographic window. There were no changes throughout the study regarding cerebral flow velocity, brain midline shift nor optic nerve sheath diameter assessments. All parameters were maintained in the physiological range without significant variations during the procedure. No perioperative complications were detected.

CONCLUSIONS

The results of our study show the feasibility to perform a perioperative assessment of cerebral flow velocity, brain midline shift or optic nerve sheath diameter jointly and successfully to obtain additional information of baseline cerebral hemodynamics in patients scheduled for elective craniotomy and their postoperative changes during the first 24 h. Future studies with lager samples are needed to address the efficacy of cerebral ultrasound as a monitoring tool.

Novel CT-based parameters assessing relative cross-sectional area to guide surgical management and predict clinical outcomes in patients with acute subdural hematoma

INTRODUCTION

Acute subdural hematoma (aSDH) is one of the most devastating entities secondary to traumatic brain injury (TBI). Even though radiological computed tomography (CT) findings, such as hematoma thickness (HT), midline shift (MLS), and MLS/HT ratio, have an important prognostic role, they suffer from important drawbacks. We hypothesized that relative cross-sectional area (rCSA) of specific brain regions would provide valuable information about brain compression and swelling, thus being a key determining factor governing the clinical course.

METHODS

We performed an 8-year retrospective analysis of patients with moderate to severe TBI with surgically evacuated, isolated, unilateral aSDH. We investigated the influence of aSDH rCSA and ipsilateral hemisphere rCSA along the supratentorial region on the subsequent operative technique employed for aSDH evacuation and patient's clinical outcomes (early death and Glasgow Outcome Scale [GOS] at discharge and after 1-year follow-up). Different conventional radiological variables were also assessed.

RESULTS

The study included 39 patients. Lower HT, MLS, hematoma volume, and aSDH rCSA showed a significant association with decompressive craniectomy (DC) procedure. Conversely, higher ipsilateral hemisphere rCSA along the dorso-ventral axis and, specifically, ipsilateral hemisphere rCSA at the high convexity level were predictors for DC. CT segmentation analysis exhibited a modest relationship with early death, which was limited to the basal supratentorial subregion, but could not predict long-term outcome.

CONCLUSION

rCSA is an objectifiable and reliable radiologic parameter available on admission CT that might provide valuable information to optimize surgical treatment.

Comparison between Transcranial Sonography and Computerized Tomography Scans to Assess the Midline Shift in Patients with Traumatic Brain Injury

Background

Midline shift (MLS) of the brain is an important clinical finding diagnosed on computed tomography (CT) imaging and transcranial sonography (TCS) can help diagnose MLS at the bedside and facilitate interventions to improve outcomes. The study aimed to find an association between TCS- and CT-based assessments of MLS in patients with traumatic brain injury (TBI).

Patients and methods

We included all adult patients with moderate-to-severe TBI of either gender, aged between 18 and 65 years, undergoing intracranial surgery under general anesthesia over a period of 3 months. Consciousness was assessed with the help of the Glasgow coma scale (GCS) and Glasgow coma scale-pupillary (GCS-P) score. We calculated MLS using a CT scan and TCS. Bland Altman graph along with Pearson's and Spearman's coefficient tests was used.

Results

A total of 17 patients were analyzed in this study. The MLS was 0.52 ± 0.90 cm using TCS and 0.58 ± 0.39 cm using CT scan. The Pearson's correlation coefficient (r ²) of the difference between MLS measured by TCS and CT imaging was 0.002 (p < 0.05).

Conclusion

Transcranial sonography could detect MLS in patients with TBI, provided a minimum time window is used between MLS measurements by TCS and CT scan.

How to cite this article

Kapoor I, Pandit S, Prabhakar H, Mahajan C. Comparison between Transcranial Sonography and Computerized Tomography Scans to Assess the Midline Shift in Patients with Traumatic Brain Injury. Indian J Crit Care Med 2023;27(1):64-66.

POCUS, how can we include the brain? An overview

Point-of-care ultrasound (POCUS) is an essential tool to assess and manage different pathologies in the intensive care unit, and many protocols have been proposed for its application in critical care literature. However, the brain has been overlooked in these protocols.

Brain ultrasonography (BU) is easily available, and it allows a goal-directed approach thanks to its repeatability and immediate interpretation and provides a quick management and real time assessment of patients’ conditions. Based on recent studies, the increasing interest from intensivists, and the undeniable benefits of ultrasound, the main goal of this overview is to describe the main evidence and progresses in the incorporation of BU into the POCUS approach in the daily practice, and thus becoming POCUS-BU. This integration would allow a noninvasive global assessment to entail an integrated analysis of the critical care patients.

Modelling glioma progression, mass effect and intracranial pressure in patient anatomy

Increased intracranial pressure is the source of most critical symptoms in patients with glioma, and often the main cause of death. Clinical interventions could benefit from non-invasive estimates of the pressure distribution in the patient's parenchyma provided by computational models. However, existing glioma models do not simulate the pressure distribution and they rely on a large number of model parameters, which complicates their calibration from available patient data. Here we present a novel model for glioma growth, pressure distribution and corresponding brain deformation. The distinct feature of our approach is that the pressure is directly derived from tumour dynamics and patient-specific anatomy, providing non-invasive insights into the patient's state. The model predictions allow estimation of critical conditions such as intracranial hypertension, brain midline shift or neurological and cognitive impairments. A diffuse-domain formalism is employed to allow for efficient numerical implementation of the model in the patient-specific brain anatomy. The model is tested on synthetic and clinical cases. To facilitate clinical deployment, a high-performance computing implementation of the model has been publicly released.

Ten Good Reasons to Practice Neuroultrasound in Critical Care Setting

In the beginning, cerebral ultrasound (US) was not considered feasible because the intact skull was a seemingly impenetrable obstacle. For this reason, obtaining a clear image resolution had been a challenge since the first use of neuroultrasound (NUS) for the assessment of small deep brain structures. However, the improvements in transducer technologies and advances in signal processing have refined the image resolution, and the role of NUS has evolved as an imaging modality for the brain parenchyma within multiple pathologies. This article summarizes ten crucial applications of cerebral ultrasonography for the evaluation and management of neurocritical patients, whose transfer from and to intensive care units poses a real problem to medical care staff. This also encompasses ease of use, low cost, wide acceptance by patients, no radiation risk, and relative independence from movement artifacts. Bedsides, availability and reliability raised the interest of critical care intensivists in using it with increasing frequency. In this mini-review, the usefulness and the advantages of US in the neurocritical care setting are discussed regarding ten aspects to encourage the intensivist physician to practice this important tool.

Accuracy of bedside bidimensional transcranial ultrasound versus tomodensitometric measurement of the third ventricle

BACKGROUND AND PURPOSE

To evaluate the accuracy of transcranial duplex sonography (TCS) for measuring the diameter of the third ventricle (DTV) and the brain midline shift (MLS), as compared to cerebral CT.

METHODS

Single-center retrospective study including 177 patients admitted to the neurological intensive care unit (NICU). We studied the correlation between TCS and CT measurements of DTV and MLS using a Bland-Altman analysis. The best threshold of DTV to diagnose acute hydrocephalus was evaluated with a receiver operating characteristic (ROC) analysis.

RESULTS

We analyzed 177 pairs of CT-TCS measurements for DTV and 165 for MLS. The mean time interval between CT and TCS was 87 ± 73 minutes. Median DTV measurement on CT was 4 ± 3 mm, and 5 ± 3 mm by TCS. Median MLS on CT was 2 ± 3 mm, and 2 ± 4 mm by TCS. The Pearson correlation coefficient (r² ) was .96 between TCS and CT measurements (p < .001). The Bland-Altman analysis found a proportional bias of 0.69 mm for the DTV with a limit of agreement ranging between -3.04 and 2.53 mm. For the MLS, the proportional bias was 0.23 mm with limits of agreements between -3.5 and 3.95. The area under the ROC curve was .97 for the detection of hydrocephalus by DTV on TCS, with a best threshold of 5.72 mm (Sensitivity [Se] = 92% Specificity [Sp] = 92.1%).

CONCLUSIONS

TCS seems to be a reliable and accurate bedside technique for measuring both DTV and MLS, which might allow detection of acute hydrocephalus among NICU patients.

Bedside detection of intracranial midline shift using portable magnetic resonance imaging

Neuroimaging is crucial for assessing mass effect in brain-injured patients. Transport to an imaging suite, however, is challenging for critically ill patients. We evaluated the use of a low magnetic field, portable MRI (pMRI) for assessing midline shift (MLS). In this observational study, 0.064 T pMRI exams were performed on stroke patients admitted to the neuroscience intensive care unit at Yale New Haven Hospital. Dichotomous (present or absent) and continuous MLS measurements were obtained on pMRI exams and locally available and accessible standard-of-care imaging exams (CT or MRI). We evaluated the agreement between pMRI and standard-of-care measurements. Additionally, we assessed the relationship between pMRI-based MLS and functional outcome (modified Rankin Scale). A total of 102 patients were included in the final study (48 ischemic stroke; 54 intracranial hemorrhage). There was significant concordance between pMRI and standard-of-care measurements (dichotomous, κ = 0.87; continuous, ICC = 0.94). Low-field pMRI identified MLS with a sensitivity of 0.93 and specificity of 0.96. Moreover, pMRI MLS assessments predicted poor clinical outcome at discharge (dichotomous: adjusted OR 7.98, 95% CI 2.07–40.04, p = 0.005; continuous: adjusted OR 1.59, 95% CI 1.11–2.49, p = 0.021). Low-field pMRI may serve as a valuable bedside tool for detecting mass effect.

Head to toe ultrasound: a narrative review of experts’ recommendations of methodological approaches

Critical care ultrasonography (US) is widely used by intensivists managing critically ill patients to accurately and rapidly assess different clinical scenarios, which include pneumothorax, pleural effusion, pulmonary edema, hydronephrosis, hemoperitoneum, and deep vein thrombosis. Basic and advanced critical care ultrasonographic skills are routinely used to supplement physical examination of critically ill patients, to determine the etiology of critical illness and to guide subsequent therapy. European guidelines now recommend the use of US for a number of practical procedures commonly performed in critical care. Full training and competence acquisition are essential before significant therapeutic decisions are made based on the US assessment. However, there are no universally accepted learning pathways and methodological standards for the acquisition of these skills.

Therefore, in this review, we aim to provide a methodological approach of the head to toe ultrasonographic evaluation of critically ill patients considering different districts and clinical applications.

Clinical and radiographic factors involved in achieving a hematoma evacuation rate of more than 70% through minimally invasive catheter drainage for spontaneous intracerebral hemorrhage

Although stereotactic or neuronavigation-guided hematoma drainage for spontaneous intracerebral hemorrhage (ICH) is widely used, its clinical efficacy and factors for predictive results remain to be fully elucidated. This study sought to determine the efficacy of hematoma evacuation for spontaneous ICH, in addition to the factors affecting it. We retrospectively reviewed patients who underwent stereotactic or neuronavigation-guided catheter insertion for spontaneous ICH at our institute between April 2010 and December 2019. We identified and compared the clinical and radiographic factors between groups according to the hematoma evacuation rate of 70%. Logistic regression analyses were performed to identify factors affecting hematoma evacuation. We investigated whether the hematoma evacuation rate was associated with patient survival. A total of 95 patients who underwent stereotactic or neuronavigation-guided catheter insertion and hematoma drainage for spontaneous ICH were included. A multivariate analysis indicated that a hematoma volume of 30-60 cm³ (odds ratio [OR] = 8.064, 95% confidence interval [CI] = 2.285-28.468, P = 0.001), blend sign (OR = 6.790, 95% CI = 1.239-37.210, P = 0.027), diabetes (OR = 0.188, 95% CI = 0.041-0.870, P = 0.032), and leukocytosis (OR = 3.061, 95% CI = 1.094-8.563, P = 0.033) were significantly associated with a higher hematoma evacuation. The mean hematoma evacuation rate in patients with 1-month mortality was lower than that in survivors (P = 0.051). Our study revealed that a hematoma volume of 30-60 cm³, the presence of a blend sign and leukocytosis, and the absence of diabetes are independent predictors that affect more than 70% of hematoma evacuations.

Management of intracranial hypertension following traumatic brain injury: a best clinical practice adoption proposal for intracranial pressure monitoring and decompressive craniectomy. Joint statements by the Traumatic Brain Injury Section of the Italian Society of Neurosurgery (SINch) and the Neuroanesthesia and Neurocritical Care Study Group of the Italian Society of Anesthesia, Analgesia, Resuscitation and Intensive Care (SIAARTI)

No robust evidence is provided by literature regarding the management of intracranial hypertension following severe traumatic brain injury (TBI). This is mostly due to the lack of prospective randomized controlled trials (RCTs), the presence of studies containing extreme heterogeneously collected populations and controversial considerations about chosen outcome. A scientific society should provide guidelines for care management and scientific support for those areas for which evidence-based medicine has not been identified. However, RCTs in severe TBI have failed to establish intervention effectiveness, arising the need to make greater use of tools such as Consensus Conferences between experts, which have the advantage of providing recommendations based on experience, on the analysis of updated literature data and on the direct comparison of different logistic realities. The Italian scientific societies should provide guidelines following the national laws ruling the best medical practice. However, many limitations do not allow the collection of data supporting high levels of evidence for intracranial pressure (ICP) monitoring and decompressive craniectomy (DC) in patients with severe TBI. This intersociety document proposes best practice guidelines for this subsetting of patients to be adopted on a national Italian level, along with joint statements from "TBI Section" of the Italian Society of Neurosurgery (SINch) endorsed by the Neuroanesthesia and Neurocritical Care Study Group of the Italian Society of Anesthesia, Analgesia, Resuscitation and Intensive Care (SIAARTI). Presented here is a recap of recommendations on management of ICP and DC supported a high level of available evidence and rate of agreement expressed by the assemblies during the more recent consensus conferences, where members of both groups have had a role of active participants and supporters. The listed recommendations have been sent to a panel of experts consisting of the 107 members of the "TBI Section" of the SINch and the 111 members of the Neuroanesthesia and Neurocritical Care Study Group of the SIAARTI. The aim of the survey was to test a preliminary evaluation of the grade of predictable future adherence of the recommendations following this intersociety proposal. The following recommendations are suggested as representing best clinical practice, nevertheless, adoption of local multidisciplinary protocols regarding thresholds of ICP values, drug therapies, hemostasis management and perioperative care of decompressed patients is strongly recommended to improve treatment efficiency, to increase the quality of data collection and to provide more powerful evidence with future studies. Thus, for this future perspective a rapid overview of the role of the multimodal neuromonitoring in the optimal severe TBI management is also provided in this document. It is reasonable to assume that the recommendations reported in this paper will in future be updated by new observations arising from future trials. They are not binding, and this document should be offered as a guidance for clinical practice through an intersociety agreement, taking in consideration the low level of evidence.

Reliability of transcranial sonography for assessment of brain midline shift in adult neurocritical patients: a systematic review and meta-analysis

INTRODUCTION

The aim of this systematic review and meta-analysis was to determine the reliability of transcranial sonography as an alternative to computed tomography for evaluation of brain midline shift in adult neurocritical patients.

EVIDENCE AQUISITION

The PubMed, EMBASE, Cochrane Library, Scopus and Web of Science databases were searched. Original studies evaluating brain midline shift in adult neurocritical patients using both transcranial sonography and computed tomography were eligible. Primary outcome measure was concordance between both methods as quantified in terms of concordance correlation coefficient. Secondary outcome measure was limits of agreement, defined as mean difference between sonography and computed tomography plus and minus 1.96 standard deviations.

EVIDENCE SYNTHESIS

Twelve studies (574 patients, 689 examinations) were eligible. Ten studies (416 patients, 492 examinations) provided adequate data for evaluation of concordance. Pooling of effect sizes showed strong concordance between both methods (concordance correlation coefficient, 0.91; 95% CI, 0.87 to 0.94). Two missing studies were imputed and effect size was adjusted to 0.88 (95% CI, 0.81 to 0.93). Nine studies (442 patients, 571 examinations) provided adequate data for estimation of limits of agreement. Pooling of effect sizes showed a bias of -0.53 mm (95% limits of agreement, -1.22 to 0.16 mm). Four missing studies were imputed and bias was adjusted to -0.68 mm (95% limits of agreement, -1.31 to -0.04 mm).

CONCLUSIONS

Transcranial sonography may serve as reliable alternative to computed tomography for evaluation of brain midline shift in adult neurocritical patients. Both methods have strong concordance with acceptably narrow limits of agreement.

Neuromonitoring Using Neurosonography and Pupillometry in A Weaning and Early Neurorehabilitation Unit

BACKGROUND AND PURPOSE

Long-term surveillance of intracranial pressure (ICP) in neurological/neurosurgical patients during ventilator weaning and early neurorehabilitation currently relies on clinical observation because neuroimaging is rarely readily available. In this prospective study, multimodal neurosonography and pupillometry are evaluated for follow-up monitoring.

METHODS

Sonographic neuromonitoring was used to noninvasively examine patients' ICP during weaning and early neurorehabilitation. It allowed assessments of third ventricle width, possible midline shift, middle cerebral artery flow velocities, and bilateral optic nerve sheath diameters. Quantitative pupillometry was used to determine pupil size and reactivity. Other neuroimaging findings, spinal tap ICP measurements, and clinical follow-up data served as controls.

RESULTS

Seventeen patients-11 suffering from intracranial hemorrhage, four from encephalopathies, and two from ischemic stroke-were examined for ICP changes by using neurosonography and pupillometry during a mean observation period of 21 days. In total, 354 of 980 analyses (36.1%) yielded pathological results. In 15 of 17 patients (88.2%), pathological values were found during follow-up without a clear clinical correlate. In two patients (11.8%), clinically relevant changes in ICP occurred and were identified using neurosonography. Abnormal pupillometry findings displayed a high predictive value for absent clinical improvement.

CONCLUSION

Multimodal neurosonography may be a noninvasive means for long-term ICP assessment, whereas pupillometry may only detect rapid ICP changes during acute neurointensive care. The study also illustrates common pitfalls in neuromonitoring in general, with large numbers of pathological albeit nonsignificant findings. Additional controlled studies should validate the influence of detected subtle changes in ICP on neurological outcome.

International evidence-based guidelines on Point of Care Ultrasound (POCUS) for critically ill neonates and children issued by the POCUS Working Group of the European Society of Paediatric and Neonatal Intensive Care (ESPNIC)

BACKGROUND

Point-of-care ultrasound (POCUS) is nowadays an essential tool in critical care. Its role seems more important in neonates and children where other monitoring techniques may be unavailable. POCUS Working Group of the European Society of Paediatric and Neonatal Intensive Care (ESPNIC) aimed to provide evidence-based clinical guidelines for the use of POCUS in critically ill neonates and children.

METHODS

Creation of an international Euro-American panel of paediatric and neonatal intensivists expert in POCUS and systematic review of relevant literature. A literature search was performed, and the level of evidence was assessed according to a GRADE method. Recommendations were developed through discussions managed following a Quaker-based consensus technique and evaluating appropriateness using a modified blind RAND/UCLA voting method. AGREE statement was followed to prepare this document.

RESULTS

Panellists agreed on 39 out of 41 recommendations for the use of cardiac, lung, vascular, cerebral and abdominal POCUS in critically ill neonates and children. Recommendations were mostly (28 out of 39) based on moderate quality of evidence (B and C).

CONCLUSIONS

Evidence-based guidelines for the use of POCUS in critically ill neonates and children are now available. They will be useful to optimise the use of POCUS, training programs and further research, which are urgently needed given the weak quality of evidence available.

Diagnostic value of transcranial ultrasonography for selecting subjects with large vessel occlusion: a systematic review

Introduction

A number of pre-hospital clinical assessment tools have been developed to triage subjects with acute stroke due to large vessel occlusion (LVO) to a specialised endovascular centre, but their false negative rates remain high leading to inappropriate and costly emergency transfers. Transcranial ultrasonography may represent a valuable pre-hospital tool for selecting patients with LVO who could benefit from rapid transfer to a dedicated centre.

Methods

Diagnostic accuracy of transcranial ultrasonography in acute stroke was subjected to systematic review. Medline, Embase, PubMed, Scopus, and The Cochrane Library were searched. Published articles reporting diagnostic accuracy of transcranial ultrasonography in comparison to a reference imaging method were selected. Studies reporting estimates of diagnostic accuracy were included in the meta-analysis.

Results

Twenty-seven published articles were selected for the systematic review. Transcranial Doppler findings, such as absent or diminished blood flow signal in a major cerebral artery and asymmetry index ≥ 21% were shown to be suggestive of LVO. It demonstrated sensitivity ranging from 68 to 100% and specificity of 78–99% for detecting acute steno-occlusive lesions. Area under the receiver operating characteristics curve was 0.91. Transcranial ultrasonography can also detect haemorrhagic foci, however, its application is largely restricted by lesion location.

Conclusions

Transcranial ultrasonography might potentially be used for the selection of subjects with acute LVO, to help streamline patient care and allow direct transfer to specialised endovascular centres. It can also assist in detecting haemorrhagic lesions in some cases, however, its applicability here is largely restricted. Additional research should optimize the scanning technique. Further work is required to demonstrate whether this diagnostic approach, possibly combined with clinical assessment, could be used at the pre-hospital stage to justify direct transfer to a regional thrombectomy centre in suitable cases.

Whole body ultrasound in the operating room and intensive care unit

Whole body ultrasound can be used to improve the speed and accuracy of evaluation of an increasing number of organ systems in the critically ill. Cardiac and abdominal ultrasound can be used to identify the mechanisms and etiology of hemodynamic instability. In hypoxemia or hypercarbia, lung ultrasound can rapidly identify the etiology of the condition with an accuracy that is equivalent to that of computed tomography. For encephalopathy, ocular ultrasound and transcranial Doppler can identify elevated intracranial pressure and midline shift. Renal and bladder ultrasound can identify the mechanisms and etiology of renal failure. Ultrasound can also improve the accuracy and safety of percutaneous procedures and should be currently used routinely for central vein catheterization and percutaneous tracheostomy.

Chemical Heat Packs as an Intervention to Prolong Ultrasound Battery Runtime

INTRODUCTION

Point-of-care ultrasonography is a burgeoning field of practice and study. Although point-of-care ultrasonography has started to penetrate the field of wilderness medicine, its use in cold environments is often limited by poor battery performance. In the current study, we investigated the effect of chemical foot warmers on battery runtime of handheld ultrasound machines in cold weather.

METHODS

This prospective study used a balanced, crossover randomization design to compare handheld ultrasound machines exposed to cold weather with and without the application of chemical foot warmers. Time to power off, ambient temperature, air humidity, and wind speed were recorded for each trial and compared in a mixed-effects model analysis of variance.

RESULTS

Ultrasound machines showed significantly decreased functional battery life with decreasing temperature (P<0.01) and increasing wind speed (P=0.01). Addition of the chemical foot warmer resulted in a statistically significant increase in handheld ultrasound machine runtime compared with controls (P<0.001). Overall machine runtime was increased by approximately 21.8 min (95% CI 16.2-27.3).

CONCLUSIONS

The application of chemical foot warmers to handheld ultrasound machines exposed to cold environments prolongs usable battery life and, consequently, may allow for extended scanning time in austere and remote environments.

Brain ultrasonography: methodology, basic and advanced principles and clinical applications. A narrative review

Brain ultrasonography can be used to evaluate cerebral anatomy and pathology, as well as cerebral circulation through analysis of blood flow velocities. Transcranial colour-coded duplex sonography is a generally safe, repeatable, non-invasive, bedside technique that has a strong potential in neurocritical care patients in many clinical scenarios, including traumatic brain injury, aneurysmal subarachnoid haemorrhage, hydrocephalus, and the diagnosis of cerebral circulatory arrest. Furthermore, the clinical applications of this technique may extend to different settings, including the general intensive care unit and the emergency department. Its increasing use reflects a growing interest in non-invasive cerebral and systemic assessment. The aim of this manuscript is to provide an overview of the basic and advanced principles underlying brain ultrasonography, and to review the different techniques and different clinical applications of this approach in the monitoring and treatment of critically ill patients.

Incorporation of Transcranial Doppler into the ED for the neurocritical care patient

INTRODUCTION

In the catastrophic neurologic emergency, a complete neurological exam is not always possible or feasible given the time-sensitive nature of the underlying disease process, or if emergent airway management is indicated. As the neurologic exam may be limited in some patients, the emergency physician is reliant on the assessment of brainstem structures to determine neurological function. Physicians thus routinely depend on advanced imaging modalities to further investigate for potential catastrophic diagnoses. Acquiring these tests introduces the risks of transport as well as delays in managing time-sensitive neurologic processes. A more immediate, non-invasive bedside approach complementing these modalities has evolved: Transcranial Doppler (TCD).

OBJECTIVE

This narrative review will provide a description of scenarios in which TCD may be applicable. It will summarize the sonographic findings and associated underlying pathophysiology in such neurocritical care patients. An illustrated tutorial, along with pearls and pitfalls, is provided.

DISCUSSION

Although there are numerous formalized TCD protocols utilizing four views (transtemporal, submandibular, suboccipital, and transorbital), point-of-care TCD is best accomplished through the transtemporal window. The core applications include the evaluation of midline shift, vasospasm after subarachnoid hemorrhage, acute ischemic stroke, and elevated intracranial pressure. An illustrative tutorial is provided.

CONCLUSIONS

With the wide dissemination of bedside ultrasound within the emergency department, there is a unique opportunity for the emergency physician to utilize TCD for a variety of conditions. While barriers to training exist, emergency physician performance of limited point-of-care TCD is feasible and may provide rapid and reliable clinical information with high temporal resolution.

Brain Midline Shift Measurement and Its Automation: A Review of Techniques and Algorithms

Midline shift (MLS) of the brain is an important feature that can be measured using various imaging modalities including X-ray, ultrasound, computed tomography, and magnetic resonance imaging. Shift of midline intracranial structures helps diagnosing intracranial lesions, especially traumatic brain injury, stroke, brain tumor, and abscess. Being a sign of increased intracranial pressure, MLS is also an indicator of reduced brain perfusion caused by an intracranial mass or mass effect. We review studies that used the MLS to predict outcomes of patients with intracranial mass. In some studies, the MLS was also correlated to clinical features. Automated MLS measurement algorithms have significant potentials for assisting human experts in evaluating brain images. In symmetry-based algorithms, the deformed midline is detected and its distance from the ideal midline taken as the MLS. In landmark-based ones, MLS was measured following identification of specific anatomical landmarks. To validate these algorithms, measurements using these algorithms were compared to MLS measurements made by human experts. In addition to measuring the MLS on a given imaging study, there were newer applications of MLS that included comparing multiple MLS measurement before and after treatment and developing additional features to indicate mass effect. Suggestions for future research are provided.

Point-of-care transcranial Doppler by intensivists

In the unconscious patient, there is a diagnostic void between the neurologic physical exam, and more invasive, costly and potentially harmful investigations. Transcranial color-coded sonography and two-dimensional transcranial Doppler imaging of the brain have the potential to be a middle ground to bridge this gap for certain diagnoses. With the increasing availability of point-of-care ultrasound devices, coupled with the need for rapid diagnosis of deteriorating neurologic patients, intensivists may be trained to perform point-of-care transcranial Doppler at the bedside. The feasibility and value of this technique in the intensive care unit to help rule-in specific intra-cranial pathologies will form the focus of this article. The proposed scope for point-of-care transcranial Doppler for the intensivist will be put forth and illustrated using four representative cases: presence of midline shift, vasospasm, raised intra-cranial pressure, and progression of cerebral circulatory arrest. We will review the technical details, including methods of image acquisition and interpretation. Common pitfalls and limitations of point-of-care transcranial Doppler will also be reviewed, as they must be understood for accurate diagnoses during interpretation, as well as the drawbacks and inadequacies of the modality in general.

Bedside sonographic measurement of optic nerve sheath diameter as a predictor of intracranial pressure in ED

BACKGROUND

Ocular ultrasonography of optic nerve sheath diameter (ONSD) to determine intracranial pressure (ICP) has become favorable in recent years.

OBJECTIVE

To demonstrate the efficacy of ONSD measurement in determining the ICP increase due to nontraumatic events in the emergency department.

METHODS

A total of 100 patients with suspected nontraumatic intracranial event were enrolled in this prospective study. Patients were divided equally into 2 groups including 50 patients as group I with pathology on cranial computed tomography (CT) and group II with normal cranial CT. Prior to CT scans, patients underwent ONSD measurement by a radiologist using 11- and 14-MHz transducers.

RESULTS

The ONSD values of groups I and II were 5.4±1.1and 4.1±0.5mm, respectively. Optic nerve sheath diameter was found to be larger on the side of lesion in patients with a lesion (P<.05). The cutoff value of the difference between ONSD values of both eyes in the presence of pathology was determined as 0.45 (sensitivity, 80%; specificity, 60%; the area under the curve, 0.794; 95% confidence interval, 0.705-0.883). The between-ONSD and midline shift size was statistically significant (r=0.366, P=.009). The cutoff value of ONSD for the detection of midline shift was determined as 5.3mm (sensitivity, 70%; specificity, 74%; the area under the curve, 0.728; 95% confidence interval, 0.585-0.871).

CONCLUSION

Optic nerve sheath diameter measurement via bedside ocular ultrasonography in patients with suspected intracranial event in the emergency department is a useful method to determine ICP increase and its severity.