Impact of shaggy aorta on intraoperative cerebral embolism during carotid artery stenting.

BACKGROUND: Careful selection of patients for carotid stenting is necessary. We suggest that patients with a shaggy aorta syndrome may be at higher risk for perioperative embolic complications. METHODS: The study is a retrospective subanalysis of the SIBERIA Trial. We included 72 patients undergoing transfemoral carotid artery stenting. Patients were monitored during the procedures using multifrequency transcranial Doppler with embolus detection and differentiation. Pre- and postprocedural (2 and 30 days) cerebral diffusion-weighted cerebral MRIs were performed. RESULTS: Forty-six patients had shaggy aorta syndrome. Intraoperative embolisms were recorded in 82.6% and 46.1% of patients with and without shaggy aorta syndrome, respectively (P=0.001). New asymptomatic ischemic brain lesions in the postoperative period occurred in 78.3% and in 26.9% of patients with and without shaggy aorta syndrome, respectively (P<0.001). There were no cases of stroke within 2 days in both groups. 3 (6.5%) cases of stroke within 30 days after the procedure were observed only in patients with shaggy aorta syndrome. There were no cases of contralateral stroke. Shaggy aorta syndrome (OR 5.54 [1.83:16.7], P=0.001) and aortic arch ulceration (OR 6.67 [1.19: 37.3], P=0.02) were independently associated with cerebral embolism. Shaggy aorta syndrome (OR 9.77 [3.14-30.37], P<0.001) and aortic arch ulceration (OR 12.9 [2.3: 72.8], P=0.003) were independently associated with ipsilateral new asymptomatic ischemic brain lesions. CONCLUSIONS: Shaggy aorta syndrome and aortic arch ulceration significantly increase the odds of intraoperative embolism and new asymptomatic ischemic brain lesions. Carotid endarterectomy or transcervical carotid stent should be selected in patients with shaggy aorta syndrome.

Association of pulsatility index with total burden of cerebral small vessel disease and cognitive impairment.

OBJECTIVE: This study investigated the correlation between the pulsatility index (PI) of the middle cerebral artery with the total burden of cerebral small vessel disease and cognitive impairment. METHOD: Information on patients hospitalized in the Department of Neurology was collected retrospectively. These patients had complete clinical and laboratory data. The middle cerebral artery PI was measured using transcranial Doppler, a Mini-Mental State Examination (MMSE) was used to assess cognitive function, and the total cerebral small vessel disease burden was assessed using magnetic resonance imaging. Patients were grouped according to their scores for total imaging burden of cerebral small vessel disease and cognitive function. Logistic regression analysis assessed the association between the PI, total imaging burden, and cognitive impairment. Spearman analysis was used to evaluate the correlation between the PI and total imaging burden and cognitive impairment, and receiver operating characteristic (ROC) curves were used to determine the predictive value of the PI for cognitive function. RESULTS: The PI was higher in the cognitive impairment (CI) group than in the no-CI group. Binary logistic regression analysis showed that increased PI was an independent risk factor for CI (OR = 1.582; 95% CI: 1.043-2.401; p = .031) and total imaging burden (OR = 1.842; 95% CI: 1.274-2.663; p = .001). Spearman analysis found that the PI correlated negatively with the MMSE score (r = -.627, p < .001). ROC curve analysis showed the PI predicted CI with an area under the curve of 0.784. The PI combined with the total imaging burden predicted CI in cerebral small vessel disease with an area under the curve of 0.832. CONCLUSION: An increased PI was associated with CI and a high imaging burden in cerebral small vessel disease patients. The PI combined with the total burden score shows a high predictive value for CI.

Imaging and blood flow characteristics of cerebrovascular fenestration malformation and its relationship with the occurrence of ischemic cerebrovascular disease.

OBJECTIVE: To explore the imaging and transcranial Doppler cerebral blood flow characteristics of cerebrovascular fenestration malformation and its relationship with the occurrence of ischemic cerebrovascular disease. METHODS: A retrospective analysis was conducted on the imaging data of 194 patients with cerebrovascular fenestration malformation who visited the Heyuan People's Hospital from July 2021 to July 2023. The location and morphology of the fenestration malformation blood vessels as well as the presence of other cerebrovascular diseases were analyzed. Transcranial Doppler cerebral blood flow detection data of patients with cerebral infarction and those with basilar artery fenestration malformation were also analyzed. RESULTS: A total of 194 patients with cerebral vascular fenestration malformation were found. Among the artery fenestration malformation, basilar artery fenestration was the most common, accounting for 46.08% (94/194). 61 patients (31.44%) had other vascular malformations, 97 patients (50%) had cerebral infarction, of which 30 were cerebral infarction in the fenestrated artery supply area. 28 patients with cerebral infarction in the fenestrated artery supply area received standardized antiplatelet, lipid-lowering and plaque-stabilizing medication treatment. During the follow-up period, these patients did not experience any symptoms of cerebral infarction or transient ischemic attack again. There were no differences in peak systolic flow velocity and end diastolic flow velocity, pulsatility index and resistance index between the ischemic stroke group and the no ischemic stroke group in patients with basal artery fenestration malformation (P > 0.05). CONCLUSION: Cerebrovascular fenestration malformation is most common in the basilar artery. Cerebrovascular fenestration malformation may also be associated with other cerebrovascular malformations. Standardized antiplatelet and statin lipid-lowering and plaque-stabilizing drugs are suitable for patients with cerebral infarction complicated with fenestration malformation. The relationship between cerebral blood flow changes in basilar artery fenestration malformation and the occurrence of ischemic stroke may not be significant.

Orbital doppler ultrasound as an ancillary test for diagnosing brain death: A prospective, single blind comparative study.

OBJECTIVE: Transcranial Doppler ultrasound (TDUS), computed tomography angiography (CTA), and transcranial Doppler ultrasound to detect cerebral blood flow are among the adjunctive tests in diagnosing brain death. This study aimed to investigate the effectiveness of orbital doppler ultrasound (ODUS). METHODS: This prospective, single-blind study included 66 patients for whom brain death was to be diagnosed. Primary outcome measures were ODUS measurements, Ophthalmic artery peak systolic velocity (PSV), end-diastolic velocity (EDV), and resistive indices (RI) measurements recorded during the brain death determination process. Secondary outcome measures were computed tomography angio (CTA), transcranial Doppler ultrasound (TDUS), and demographic data. RESULTS: This study investigating the effectiveness of ODUS in diagnosing brain death provided diagnostic success with 100% sensitivity and 93% specificity compared to CT angiography. It was noted that anatomical variations may limit its use. CONCLUSION: ODUS was found to have high sensitivity and specificity in the diagnosis of clinical brain death. It may assist in early prognostic assessment and shorten patient follow-up and diagnostic processes.

Association of hydroxyurea adherence with transcranial Doppler screenings in children with sickle cell disease.

BACKGROUND: National sickle cell disease (SCD) guidelines recommend oral hydroxyurea (HU) starting at 9 months of age, and annual transcranial Doppler (TCD) screenings to identify stroke risk in children aged 2-16 years. We examined prevalence and proportion of TCD screenings in North Carolina Medicaid enrollees to identify associations with sociodemographic factors and HU adherence over 3 years. STUDY DESIGN: We conducted a longitudinal study with children ages 2-16 years with SCD enrolled in NC Medicaid from years 2016-2019. Prevalence of TCD screening claims was calculated for 3 years, and proportion was calculated for 12, 24, and 36 months of Medicaid enrollment. Enrollee HU adherence was categorized using HU proportion of days covered. Multivariable Poisson regression assessed for TCD screening rates by HU adherence, controlling for age, sex, and rurality. RESULTS: The prevalence of annual TCD screening was between 39.5% and 40.1%. Of those with 12-month enrollment, 77.8% had no TCD claims, compared to 22.2% who had one or higher TCD claims. Inversely, in children with 36 months of enrollment, 36.7% had no TCD claims compared to 63.3% who had one or higher TCD claims. The proportion of children with two or higher TCD claims increased with longer enrollment (10.5% at 12 months, 33.7% at 24 months, and 52.6% at 36 months). Children with good HU adherence were 2.48 (p < .0001) times more likely to have TCD claims than children with poor HU adherence. CONCLUSION: While overall TCD screening prevalence was low, children with better HU adherence and longer Medicaid enrollment had more TCD screenings. Multilevel interventions are needed to engage healthcare providers and families to improve both evidence-based care and annual TCD screenings in children with SCD.

Intracranial Pressure and Cerebral Hemodynamics in Infants Before and After Glenn Procedure.

OBJECTIVES: This prospective cohort study aimed to investigate changes in intracranial pressure (ICP) and cerebral hemodynamics in infants with congenital heart disease undergoing the Glenn procedure, focusing on the relationship between superior vena cava pressure and estimated ICP. DESIGN: A single-center prospective cohort study. SETTING: The study was conducted in a cardiac center over 4 years (2019-2022). PATIENTS: Twenty-seven infants with congenital heart disease scheduled for the Glenn procedure were included in the study, and detailed patient demographics and primary diagnoses were recorded. INTERVENTIONS: Transcranial Doppler (TCD) ultrasound examinations were performed at three time points: baseline (preoperatively), postoperative while ventilated (within 24-48 hr), and at discharge. TCD parameters, blood pressure, and pulmonary artery pressure were measured. MEASUREMENTS AND MAIN RESULTS: TCD parameters included systolic flow velocity, diastolic flow velocity (dFV), mean flow velocity (mFV), pulsatility index (PI), and resistance index. Estimated ICP and cerebral perfusion pressure (CPP) were calculated using established formulas. There was a significant postoperative increase in estimated ICP from 11 mm Hg (interquartile range [IQR], 10-16 mm Hg) to 15 mm Hg (IQR, 12-21 mm Hg) postoperatively (p = 0.002) with a trend toward higher CPP from 22 mm Hg (IQR, 14-30 mm Hg) to 28 mm Hg (IQR, 22-38 mm Hg) postoperatively (p = 0.1). TCD indices reflected alterations in cerebral hemodynamics, including decreased dFV and mFV and increased PI. Intracranial hemodynamics while on positive airway pressure and after extubation were similar. CONCLUSIONS: Glenn procedure substantially increases estimated ICP while showing a trend toward higher CPP. These findings underscore the intricate interaction between venous pressure and cerebral hemodynamics in infants undergoing the Glenn procedure. They also highlight the remarkable complexity of cerebrovascular autoregulation in maintaining stable brain perfusion under these circumstances.

Transcranial Ultrasound in the Neurocritical Care Unit.

Ultrasound evaluation of the brain is performed through acoustic windows. Transcranial Doppler has long been used to monitor patients with subarachnoid hemorrhage for cerebral vasospasm. Transcranial color-coded sonography permits parenchymal B-mode imaging and duplex evaluation. Transcranial ultrasound may also be used to assess the risk of delayed cerebral ischemia, screen patients for the presence of elevated intracranial pressure, confirm the diagnosis of brain death, measure midline shift, and detect ventriculomegaly. Transcranial ultrasound should be integrated with other point-of-care ultrasound techniques as an essential skill for the neurointensivist.

Neurovascular ultrasound in acute stroke: emergency department applications.

Acute stroke is one of the most common neurologic emergencies encountered by emergency clinicians. While point of care ultrasound has been a core part of emergency clinicians' training and practice for many years, the use of specialized ultrasound modalities in the care of acute ischemic stroke has not been as widely adopted. This review discusses the use of ultrasound in acute stroke, with a focus on applications of interest to emergency clinicians. Transcranial Doppler, carotid Doppler, microembolic signal detection, transthoracic echocardiography, evaluation for collateral circulation and optic nerve sheath diameter measurement are discussed in a case-based format, with a focus on practical applications for emergency clinicians.

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.

National Quality Indicators in Pediatric Sickle Cell Anemia.

OBJECTIVE: To assess nationally endorsed claims-based quality measures in pediatric sickle cell anemia (SCA). METHODS: Using data from the Sickle Cell Data Collection programs in California and Georgia from 2010 to 2019, we evaluated 2 quality measures in individuals with hemoglobin S/S or S/ß-zero thalassemia: (1) the proportion of patients aged 3 months to 5 years who were dispensed antibiotic prophylaxis for at least 300 days within each measurement year and (2) the proportion of patients aged 2 to 15 years who received at least 1 transcranial Doppler ultrasound (TCD) within each measurement year. We then evaluated differences by year and tested whether performance on quality measures differed according to demographic and clinical factors. RESULTS: Only 22.2% of those in California and 15.5% in Georgia met or exceeded the quality measure for antibiotic prophylaxis, with increased odds associated with rural residence in Georgia (odds ratio 1.61; 95% confidence interval 1.21-2.14) compared with urban residence and a trend toward increased odds associated with a pediatric hematologist prescriber (odds ratio 1.28; 95% confidence interval 0.97, 1.69) compared with a general pediatrician. Approximately one-half of the sample received an annual assessment of stroke risk using TCD (47.4% in California and 52.7% in Georgia), with increased odds each additional year in both states and among younger children. CONCLUSIONS: The rates of receipt of recommended antibiotic prophylaxis and annual TCD were low in this sample of children with SCA. These evidence-based quality measures can be tracked over time to help identify policies and practices that maximize survival in SCA.

[Functional transcranial dopplerography is a diagnostic tool for cognitive impairment syndrome]. / Funktsional'naya transkranial'naya dopplerografiya v diagnostike kognitivnykh narushenii.

Functional transcranial dopplerography (FTCD) is a non-invasive ultrasound examination that allows recording the dynamics of cerebral blood flow parameters under conditions of factors stimulated the activity of the structures of the central nervous system. Judgments about the sensitivity and specificity of FTCD are based on the close connection between changes in the activity of the nervous (somatic) system and the response of regional cerebral blood flow (CBF). The technique is a portable and accessible diagnostic method used in assessing the possibility of expanding functional activity during the recovery period after a stroke. An increase in mental activity in response to the presentation of a cognitive task, accompanied by an increase in glucose and oxygen consumption and naturally requiring an increase in cerebral perfusion parameters, can also be assessed by changes in regional blood flow parameters while maintaining the reactive mechanisms of autoregulation. A search of literature sources was carried out in the electronic databases PubMed and Scopus. For the subject search, Medical Subject Headings were used. A total of 36 sources that mentioned the terms «cognitive function¼ and «functional transcranial Doppler¼ were selected for preliminary analysis. At the present stage, methodological problems are obvious, requiring the development and implementation of a standard package of targeted functional tests to assess cognitive status. Available equipment and software require technological solutions to ensure objective recording of changes in cerebral blood flow during testing and training.

Monitoring of cerebral blood flow autoregulation: physiologic basis, measurement, and clinical implications.

Cerebral blood flow (CBF) autoregulation is the physiologic process whereby blood supply to the brain is kept constant over a range of cerebral perfusion pressures ensuring a constant supply of metabolic substrate. Clinical methods for monitoring CBF autoregulation were first developed for neurocritically ill patients and have been extended to surgical patients. These methods are based on measuring the relationship between cerebral perfusion pressure and surrogates of CBF or cerebral blood volume (CBV) at low frequencies (<0.05 Hz) of autoregulation using time or frequency domain analyses. Initially intracranial pressure monitoring or transcranial Doppler assessment of CBF velocity was utilised relative to changes in cerebral perfusion pressure or mean arterial pressure. A more clinically practical approach utilising filtered signals from near infrared spectroscopy monitors as an estimate of CBF has been validated. In contrast to the traditional teaching that 50 mm Hg is the autoregulation threshold, these investigations have found wide interindividual variability of the lower limit of autoregulation ranging from 40 to 90 mm Hg in adults and 20-55 mm Hg in children. Observational data have linked impaired CBF autoregulation metrics to adverse outcomes in patients with traumatic brain injury, ischaemic stroke, subarachnoid haemorrhage, intracerebral haemorrhage, and in surgical patients. CBF autoregulation monitoring has been described in both cardiac and noncardiac surgery. Data from a single-centre randomised study in adults found that targeting arterial pressure during cardiopulmonary bypass to above the lower limit of autoregulation led to a reduction of postoperative delirium and improved memory 1 month after surgery compared with usual care. Together, the growing body of evidence suggests that monitoring CBF autoregulation provides prognostic information on eventual patient outcomes and offers potential for therapeutic intervention. For surgical patients, personalised blood pressure management based on CBF autoregulation data holds promise as a strategy to improve patient neurocognitive outcomes.

Transcranial Doppler cerebrovascular reactivity: Thresholds for clinical significance in cerebrovascular disease.

BACKGROUND AND PURPOSE: Thresholds for abnormal transcranial Doppler cerebrovascular reactivity (CVR) studies are poorly understood, especially for patients with cerebrovascular disease. Using a real-world cohort with cerebral arterial stenosis, we sought to describe a clinically significant threshold for carbon dioxide reactivity (CO2R) and vasomotor range (VMR). METHODS: CVR studies were performed during conditions of breathing room air normally, breathing 8% carbon dioxide air mixture, and hyperventilation. The mean and standard deviation (SD) of CO2R and VMR were calculated for the unaffected side in patients with unilateral stenosis; a deviation of 2 SDs below the mean was chosen as the threshold for abnormal. Receiver operating characteristic (ROC) curves for both sides for patients with unilateral and bilateral stenosis were evaluated for sensitivity (Sn) and specificity (Sp). RESULTS: A total of 133 consecutive CVR studies were performed on 62 patients with stenosis with mean±SD age 55±16 years. Comorbidities included hypertension (60%), diabetes (15%), stroke (40%), and smoking (35%). In patients with unilateral stenosis, mean±SD CO2R for the unaffected side was 1.86±0.53%, defining abnormal CO2R as <0.80%. Mean±SD CO2R for the affected side was 1.27±0.90%. The CO2R threshold predicted abnormal acetazolamide single-photon emission computed tomography (SPECT) (Sn = .73, Sp = .79), CT/MRI perfusion abnormality (Sn = .42, Sp = .77), infarction on MRI (Sn = .45, Sp = .76), and pressure-dependent exam (Sn = .50, Sp = .76). For the unaffected side, mean±SD VMR was 39.5±15.8%, defining abnormal VMR as <7.9%. For the affected side, mean±SD VMR was 26.5±17.8%. The VMR threshold predicted abnormal acetazolamide SPECT (Sn = .46, Sp = .94), infarction on MRI (Sn = .27, Sp = .94), and pressure-dependent exam (Sn = .31, Sp = .90). CONCLUSIONS: In patients with multiple vascular risk factors, a reasonable threshold for clinically significant abnormal CO2R is <0.80% and VMR is <7.9%. Noninvasive CVR may aid in diagnosing and risk stratifying patients with stenosis.

The prediction of estimated cerebral perfusion pressure with trans-systolic time in preterm and term infants.

It is important to monitor cerebral perfusion in infants because hypo- and hyperperfusion can contribute to neurological injury. This study aimed to clarify the relationship between trans-systolic time (TST) and critical closing pressure (CrCP) or estimated cerebral perfusion pressure (CPPe) in neonates. Moreover, we aimed to determine the TST values in preterm and term infants with stable cerebral perfusion to clarify normative reference data. This multicentre prospective study included infants with arterial lines admitted to the neonatal intensive care units between December 2021 and August 2023. TST, CrCP, and CPPe were calculated using middle cerebral artery waveforms recorded using transcranial Doppler ultrasonography when clinicians collected arterial blood samples. Three hundred and sixty samples were obtained from 112 infants with a gestational age of 32 (interquartile range, 27-37) weeks and a birth weight of 1481 (956-2355) g. TST was positively correlated with CPPe (r = 0.60, p < 0.001), but not with CrCP (r = 0.08, p = 0.10). The normative reference values of TST in preterm and term infants without samples of hyper- or hypocapnia and/or hyper- or hypotension, which may affect cerebral perfusion, were as follows: ≤ 29 weeks, 0.12 (0.11-0.14) s; 30-36 weeks, 0.14 (0.12-0.15) s; and ≥ 37 weeks, 0.16 (0.14-0.17) s, respectively.  Conclusion: TST in neonates significantly correlated with CPPe, but not with CrCP. TST may be a good predictor of cerebral perfusion and potentially have wider clinical applications. What is Known: • Trans-systolic time (TST) is used in evaluating the effects of increased intracranial pressure on cerebral haemodynamics. However, little is known about the efficacy of TST in predicting neonatal cerebral perfusion pressure. What is New: • This study added evidence that TST correlated with estimated cerebral perfusion pressure, but not with critical closing pressure. Additionally, we showed the normative reference values of the TST in preterm and term infants.

Clinical findings of hyperechoic substantia nigra in patients with Parkinson's disease.

This study aims to analyse hyperechoic substantia nigra (HSN) characteristics and the correlation of HSN with clinical features and blood biomarkers in patients with Parkinson's disease (PD). Transcranial sonography (TCS) evaluations of the substantia nigra (SN) were performed in 40 healthy controls and 71 patients with PD, including patients with SN hyperechogenicity (SN+) and those with normal SN echogenicity (SN-). Evaluation of motor and non-motor symptoms was assessed by a series of rating scales. The uricase method was used to determine serum uric acid (UA) levels, and enzyme-linked immunosorbent assay (ELISA) was used to measure plasma interleukin (IL)-1ß levels. TCS showed 92.50% specificity and 61.97% sensitivity in differentiating PD patients from controls. The area of SN+ contralateral to the side of initial motor symptoms (SNcontra) was larger than that ipsilateral to the side of initial motor symptoms (SNipsi). The PDSN+ group had lower Argentine Hyposmia Rating Scale (AHRS) scores and UA levels than the PDSN- group. Binary logistic regression analysis revealed that AHRS scores and UA levels could be independent predictors for HSN. The larger SN echogenic area (SNL) sizes positively correlated with plasma IL-1ß levels in PD patients with SN+. The present study provides further evidence of the potential of SN echogenicity as an imaging biomarker for PD diagnosis. PD patients with HSN have more severe non-motor symptoms of hyposmia. HSN in PD patients is related to the mechanism of abnormal iron metabolism and microglial activation.

Establishing continuum in Transcranial Doppler characteristics of IIH, migraine and healthy controls- An exploratory study.

BACKGROUND: IIH is a severe form of headache that often has superimposed migraine and often it is very difficult to distinguish the two forms of headache. Intracranial hemodynamics is a relatively unexplored means of distinguishing between the two forms of headache. OBJECTIVES: We aimed to study intracranial flow dynamics using Transcranial Doppler in patients with IIH, migraine, and normal controls. MATERIALS AND METHODS: It was a hospital-based observational study that included 51 people with IIH, 87 people with migraine, and 101 healthy controls and all were subjected to TCD study after detailed clinical examination. RESULTS: Mean age of patients in three groups were similar with the mean age in IIH being 33.41 ± 10.75 (age in years ± SD). Vision loss was present in 66.67% of patients with IIH, and most common field defect was generalized constriction (27.5%). Neuroimaging was abnormal in 94.11% of patients of IIH with mean CSF pressure was 31.27±5.32 cm of water. Of all the TCD-measured velocities, mean flow velocity (MFV) showed a significant difference in all three groups with (p-value <0.001). The pulsatility index, both for middle cerebral arteries as well as ophthalmic arteries showed a significant difference in the three groups with the highest values in IIH patients (p-value<.001). The mean VMR in IIH (1.11±0.32) was lower than the mean VMR in migraine (1.34±0.43) as well as controls (1.49±0.46). CONCLUSION: TCD parameters like MFV and PI are useful parameters that show considerable variation and can be used to differentiate between IIH and migraine.

Multimodal monitoring in patients with acute brain injury - A survey from critical care providers.

BACKGROUND: Multimodal neuromonitoring (MMM) aims to improve outcome after acute brain injury, and thus admission in specialized Neurocritical Care Units with potential access to MMM is necessary. Various invasive and noninvasive modalities have been developed, however there is no strong evidence to support monitor combinations nor is there a known standardized approach. The goal of this study is to identify the most used invasive and non-invasive neuromonitoring modalities in daily practice as well as ubiquitousness of MMM standardization. METHODS: In order to investigate current availability and protocolized implementation of MMM among neurocritical care units in US and non-US intensive care units, we designed a cross-sectional survey consisting of a self-administered online questionnaire of 20 closed-ended questions disseminated by the Neurocritical Care Society. RESULTS: Twenty-one critical care practitioners responded to our survey with a 76% completion rate. The most commonly utilized non-invasive neuromonitoring modalities were continuous electroencephalography followed by transcranial doppler. The most common invasive modalities were external ventricular drain followed by parenchymal intracranial pressure (ICP) monitoring. MMM is most utilized in patients with subarachnoid hemorrhage and there were no differences regarding established institutional protocol, 24-h cEEG availability and invasive monitor placement between teaching and non-teaching hospitals. MMM is considered standard of care in 28% of responders' hospitals, whereas in 26.7% it is deemed experimental and only done as part of clinical trials. Only 26.7% hospitals use a computerized data integration system. CONCLUSION: Our survey revealed overall limited use of MMM with no established institutional protocols among institutions. Ongoing research and further standardization of MMM will clarify its benefit to patients suffering from severe brain injury.

Ultrasonografía transcraneal en el paciente crítico / Transcranial sonography in the critical patient

La ultrasonografía transcraneal es una técnica no invasiva y disponible a pie de cama que se ha convertido en una herramienta accesible y consolidada en la evaluación y el manejo clínico de los pacientes neurocríticos. Se trata de una técnica en continuo crecimiento cuyos fundamentos (y sus limitaciones) deben ser conocidos por el intensivista. Esta revisión aporta un enfoque práctico para el intensivista, incluyendo las diferentes ventanas y planos de insonación y su papel en la patología específica propia de los pacientes neurocríticos y en los pacientes críticos de otras etiologías. (AU)

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. (AU)

Cold stimulation of the oral cavity redistributes blood towards the brain in healthy volunteers.

BACKGROUND: The aim of this study was to analyze cold stimulation-induced changes in cerebral and cardiac hemodynamics. METHODS: Upon ingestion of an ice cube, the changes in resistance index, mean flow velocity and flow index of the middle cerebral arteries (MCA) were assessed using transcranial Doppler sonography. Extracranial duplex sonography was used to measure the mean flow velocity and resistance index of the right internal carotid artery (ICA). The change in mean arterial pressure, heart rate, root mean square of successive differences (RMSSD) and end-tidal carbon dioxide pressure were analyzed additionally. These changes were compared to sham stimulation. RESULTS: Compared with sham stimulation, cooling of the oral cavity resulted in significant changes in cerebral and cardiac hemodynamics. The cold stimulation decreased the resistance index in the MCA (-4.5% ± 5.4%, p < 0.0001) and right ICA (-6.3% ± 15.6%, p = 0.001). This was accompanied by an increase in mean flow velocity (4.1% ± 8.0%, p < 0.0001) and flow index (10.1% ± 43.6%, p = 0.008) in the MCA. The cardiac effects caused an increase in mean arterial pressure (1.8% ± 11.2%, p = 0.017) and RMSSD (55% ± 112%, p = 0.048), while simultaneously decreasing the heart rate (-4.3% ± 9.6%, p = 0.0001). CONCLUSION: Cooling of the oral cavity resulted in substantial changes in cerebral and cardiac hemodynamics resulting in a blood flow diversion to the brain.