This procedure adheres to the ethical standards of the institutional committee on human experimentation and the Helsinki Declaration. Ultrasound is considered a minimal-risk procedure; therefore, written consent from the patient is generally not required. Patients with concerns about neurological changes in an appropriate clinical setting were included in the study. Those with open head wounds, surgical incisions, or surgical dressings at the insonation site were excluded. The consumables and equipment used in this study are listed in the Table of Materials.
1. Transducer selection
<ol>
	<li>Select the phased-array probe (1-5 MHz) for TCCD scan. This probe provides the smallest footprint for insonation of the transtemporal window. 
	NOTE: The term &#34;phased-array probe&#34; is often used to refer to the linear phased-array sector arc probe6,10. This terminology can be ambiguous, as all contemporary ultrasound transducers utilize phasing to direct the ultrasound beam. To keep things concise, this review will use &#34;phased-array probe&#34; in place of &#34;linear phased-array sector arc probe.</li>
</ol>
2. Machine settings
<ol>
	<li>Set the machine to the transcranial preset. This preset is available in most modern machines. This sets the indicator to the right of the screen. 
	NOTE: If Transcranial preset is not available, the Cardiac preset can be utilized. The indicator will be to the left of the screen for this preset.
	<ol>
		<li>Set the initial mode to B-Mode (2-dimensional grayscale11). Set Depth 13-16 cm. 
		NOTE: This depth will capture a hyperechoic convex line, which represents the ipsilateral temporal bone, usually at a depth of about 1-2 cm. Whereas the contralateral temporal bone will be seen as concave hyperechoic structure at depth of 14-16 cm.</li>
		<li>For the best scanning ergonomics, position the machine so that the ultrasound screen is directly in line with the ultrasound probe.</li>
	</ol>
	</li>
</ol>
3. Patient position
<ol>
	<li>Place the patient in a supine position with the head of the bed at 30 degrees.</li>
</ol>
4. Scanning technique
<ol>
	<li>Apply Gel to the probe.</li>
	<li>Place the probe on the transtemporal window (Figure 1), parallel to the ground with the index mark aimed towards the patient anterior. 
	NOTE: The transtemporal area lies just above the zygomatic arch and infront of the tragus of the ear6.</li>
</ol>
5. Transcranial views
<ol>
	<li>Use a sliding motion to scan through the nearby brain tissue until the intracranial structures that are relevant are identified. These act as a starting point to identify the landmarks needed for PoCUS TCCD.</li>
	<li>Identify the ipsilateral temporal bone, which is typically seen at around 1 cm11.</li>
	<li>Identify the contralateral temporal bone, which is typically around 14-16 cm11. 
	NOTE: The ipsilateral temporal window appears as a concave or linear hyperechoic structure. The contralateral temporal window is more concave looking11.</li>
	<li>Identify the third ventricle, which appears as two hyperechoic lines with a thin hypoechoic structure in between which represent cerebrospinal fluid. 
	NOTE: This is typically seen at depth of 6-8 cm11. Use sliding or sweeping motion until structure above is identified12. This is not an essential step for this protocol. If not clearly identified can proceed with the next step.</li>
</ol>
6. Color Doppler interrogation of the middle cerebral artery (MCA)
<ol>
	<li>Start with the view obtained from the step in the prior section.</li>
	<li>Start by reducing the depth to have the far field be 10 cm.</li>
	<li>On the left side of the top half of the ultrasound screen locates the large color flow sampling box. 
	NOTE: The MCA should now appear as a linear structure with blood flow directed towards the ultrasound transducer. Red color indicates flow moving towards the transducer.</li>
	<li>Initiate Pulse Wave Doppler and center the box over the MCA`s red color flow signal.</li>
	<li>Obtain a Spectral Doppler wave form. 
	NOTE: Normal MCA blood flow velocity displays a sharp systolic upstroke followed by a gradual deceleration during diastole13.
	<ol>
		<li>Trace the contour to measure the velocity time Integral for one cardiac cycle. 
		NOTE: In ultrasound with transcranial mode, multiple values will automatically be generated once the tracing is complete.</li>
		<li>Ensure that MFV or Time Average Velocity (TAV) or Time adjusted peak velocity (TAP) or Time average maximum Velocity (TAMAX) is displayed. If not, calculate2 it by (PSV + (EDV x 2))/3. 
		NOTE: Mean flow velocity above 120 could raise the concern for possible increased risks of vasospasm. The Angle of insonation must ideally be between 0-30 degrees otherwise measured velocities will be underestimated14. Mean flow velocity (MFV), Time adjusted peak velocity (TAP), Time average maximum Velocity (TAMAX) and Time Average velocity (TAV) will be used interchangeably.</li>
		<li>Ensure that Pulsatility index is displayed. If not, calculate it by using the formula PSV-EDV)/MFV15. 
		NOTE: The PI can be converted to an estimate of ICP using the following formula: ICP = (10.93 x PI)-1.28. Progression to PI &#62; 2 could raise the concern for elevated ICP16. PI is resistant to off-axis insonation as it is a relative ratio. All measurements in this value will be affected equally thus PI value will remain preserved17.</li>
	</ol>
	</li>
</ol>
7. Post-procedural steps
<ol>
	<li>Review the acquired images and Doppler spectra to ensure that they meet diagnostic quality standards.</li>
	<li>Ensure that all images and Doppler data are properly saved and labeled for future reference and analysis.</li>
	<li>Inform the patient about any follow-up steps or additional tests if required.</li>
</ol>

Standardizing PoC TCCD Ultrasound Protocols for Critical Care in Adults

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	<li>Aaslid, R., Markwalder, T. M., Nornes, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Noninvasive+transcranial+Doppler+ultrasound+recording+of+flow+velocity+in+basal+cerebral+arteries.">Noninvasive transcranial Doppler ultrasound recording of flow velocity in basal cerebral arteries.</a> J Neurosurg. 57 (6), 769-774 (1982).</li><li>Nicoletto, H. A., Burkman, M. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Transcranial+Doppler+series+part+II:+Performing+a+transcranial+Doppler.">Transcranial Doppler series part II: Performing a transcranial Doppler.</a> Am J Electroneurodiag Technol. 49 (1), 14-27 (2009).</li><li>Gunda, S. T., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+comparative+study+of+transcranial+color-coded+Doppler+(TCCD)+and+transcranial+Doppler+(TCD)+ultrasonography+techniques+in+assessing+the+intracranial+cerebral+arteries+haemodynamics.">A comparative study of transcranial color-coded Doppler (TCCD) and transcranial Doppler (TCD) ultrasonography techniques in assessing the intracranial cerebral arteries haemodynamics.</a> Diagnostics (Basel). 14 (4), 387 (2024).</li><li>Caldas, J., Rynkowski, C. B., Robba, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=POCUS,+how+can+we+include+the+brain?+An+overview.">POCUS, how can we include the brain? An overview.</a> J Anesth Analg Crit Care. 2 (1), 55 (2022).</li><li>Rajajee, V., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Transcranial+color-coded+sonography+with+angle+correction+as+a+screening+tool+for+raised+intracranial+pressure.">Transcranial color-coded sonography with angle correction as a screening tool for raised intracranial pressure.</a> Crit Care Explor. 5 (9), e0953 (2023).</li><li>Bathala, L., Mehndiratta, M., Sharma, V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Transcranial+Doppler:+Technique+and+common+findings+(part+1).">Transcranial Doppler: Technique and common findings (part 1).</a> Ann Indian Acad Neurol. 16 (2), 174 (2013).</li><li>Barlinn, K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Increased+pulsatility+of+the+intracranial+blood+flow+spectral+waveform+on+transcranial+Doppler+does+not+point+to+peripheral+arterial+disease+in+stroke+patients.">Increased pulsatility of the intracranial blood flow spectral waveform on transcranial Doppler does not point to peripheral arterial disease in stroke patients.</a> J Stroke Cerebrovas Dis. 24 (1), 189-195 (2015).</li><li>Bronshteyn, Y. S., Blitz, J., Hashmi, N., Krishnan, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Logistics+of+perioperative+diagnostic+point-of-care+ultrasound:+Nomenclature,+scope+of+practice,+training,+credentialing/privileging,+and+billing.">Logistics of perioperative diagnostic point-of-care ultrasound: Nomenclature, scope of practice, training, credentialing/privileging, and billing.</a> Int Anesthesiol Clin. 60 (3), 1-7 (2022).</li><li>Robba, C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Basic+ultrasound+head-to-toe+skills+for+intensivists+in+the+general+and+neuro+intensive+care+unit+population:+Consensus+and+expert+recommendations+of+the+european+society+of+intensive+care+medicine.">Basic ultrasound head-to-toe skills for intensivists in the general and neuro intensive care unit population: Consensus and expert recommendations of the european society of intensive care medicine.</a> Intensive Care Med. 47 (12), 1347-1367 (2021).</li><li>Fischetti, A. J., Scott, R. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Basic+ultrasound+beam+formation+and+instrumentation.">Basic ultrasound beam formation and instrumentation.</a> Clin Tech Small Anim Pract. 22 (3), 90-92 (2007).</li><li>. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Aium+practice+guideline+for+the+performance+of+a+transcranial+Doppler+ultrasound+examination+for+adults+and+children.">Aium practice guideline for the performance of a transcranial Doppler ultrasound examination for adults and children.</a> J Ultrasound Med. 31 (9), 1489-1500 (2012).</li><li>Lau, V. I., Arntfield, R. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Point-of-care+transcranial+Doppler+by+intensivists.">Point-of-care transcranial Doppler by intensivists.</a> Crit Ultrasound J. 9 (1), 21 (2017).</li><li>Naqvi, J., Yap, K. H., Ahmad, G., Ghosh, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Transcranial+Doppler+ultrasound:+A+review+of+the+physical+principles+and+major+applications+in+critical+care.">Transcranial Doppler ultrasound: A review of the physical principles and major applications in critical care.</a> Int J Vasc Med. 2013, 1-13 (2013).</li><li>Lepic, T., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Importance+of+angle+corection+in+transcranial+color-coded+duplex+insonation+of+arteries+at+the+base+of+the+brain.">Importance of angle corection in transcranial color-coded duplex insonation of arteries at the base of the brain.</a> Vojnosanit Pregl. 72 (12), 1093-1097 (2015).</li><li>Gosling, R. G., King, D. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+role+of+measurement+in+peripheral+vascular+surgery:+Arterial+assessment+by+Doppler-shift+ultrasound.">The role of measurement in peripheral vascular surgery: Arterial assessment by Doppler-shift ultrasound.</a> Proc Royal Soc Med. 67 (6P1), 447-449 (1974).</li><li>Chan, K. -. H., Miller, J. D., Dearden, N. M., Andrews, P. J. D., Midgley, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+effect+of+changes+in+cerebral+perfusion+pressure+upon+middle+cerebral+artery+blood+flow+velocity+and+jugular+bulb+venous+oxygen+saturation+after+severe+brain+injury.">The effect of changes in cerebral perfusion pressure upon middle cerebral artery blood flow velocity and jugular bulb venous oxygen saturation after severe brain injury.</a> J Neurosurg. 77 (1), 55-61 (1992).</li><li>White, H., Venkatesh, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Applications+of+transcranial+Doppler+in+the+ICU:+A+review.">Applications of transcranial Doppler in the ICU: A review.</a> Intensive Care Med. 32 (7), 981-994 (2006).</li><li>Alexandrov, A. V., Neumyer, M. M., Alexandrov, A. V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Cerebrovascular ultrasound in stroke prevention and treatment. , 17-32 (2004).</li><li>Alexandrov, A. V., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Practice+standards+for+transcranial+Doppler+(TCD)+ultrasound.+Part+II.+Clinical+indications+and+expected+outcomes.">Practice standards for transcranial Doppler (TCD) ultrasound. Part II. Clinical indications and expected outcomes.</a> J Neuroimaging. 22 (3), 215-224 (2012).</li><li>Bellner, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Transcranial+Doppler+sonography+pulsatility+index+(pi)+reflects+intracranial+pressure+(icp).">Transcranial Doppler sonography pulsatility index (pi) reflects intracranial pressure (icp).</a> Surg Neurol. 62 (1), 45-51 (2004).</li><li>Czosnyka, M., Matta, B. F., Smielewski, P., Kirkpatrick, P. J., Pickard, J. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cerebral+perfusion+pressure+in+head-injured+patients:+A+noninvasive+assessment+using+transcranial+Doppler+ultrasonography.">Cerebral perfusion pressure in head-injured patients: A noninvasive assessment using transcranial Doppler ultrasonography.</a> J Neurosurg. 88 (5), 802-808 (1998).</li><li>Nedelmann, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Consensus+recommendations+for+transcranial+color-coded+duplex+sonography+for+the+assessment+of+intracranial+arteries+in+clinical+trials+on+acute+stroke.">Consensus recommendations for transcranial color-coded duplex sonography for the assessment of intracranial arteries in clinical trials on acute stroke.</a> Stroke. 40 (10), 3238-3244 (2009).</li><li>Rasulo, F. A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Transcranial+Doppler+as+a+screening+test+to+exclude+intracranial+hypertension+in+brain-injured+patients:+The+impressit-2+prospective+multicenter+international+study.">Transcranial Doppler as a screening test to exclude intracranial hypertension in brain-injured patients: The impressit-2 prospective multicenter international study.</a> Critical Care. 26 (1), 110 (2022).</li><li>Robba, C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Basic+ultrasound+head-to-toe+skills+for+intensivists+in+the+general+and+neuro+intensive+care+unit+population:+Consensus+and+expert+recommendations+of+the+european+society+of+intensive+care+medicine.">Basic ultrasound head-to-toe skills for intensivists in the general and neuro intensive care unit population: Consensus and expert recommendations of the european society of intensive care medicine.</a> Intensive Care Med. 47 (12), 1347-1367 (2021).</li><li>Chang, J. J., Tsivgoulis, G., Katsanos, A. H., Malkoff, M. D., Alexandrov, A. V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Diagnostic+accuracy+of+transcranial+Doppler+for+brain+death+confirmation:+Systematic+review+and+meta-analysis.">Diagnostic accuracy of transcranial Doppler for brain death confirmation: Systematic review and meta-analysis.</a> Am J Neurorad. 37 (3), 408-414 (2016).</li><li>Baumgartner, R. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Transcranial+color-coded+duplex+sonography.">Transcranial color-coded duplex sonography.</a> J Neurol. 246 (8), 637-647 (1999).</li><li>Hassler, W., Steinmetz, H., Pirschel, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Transcranial+Doppler+study+of+intracranial+circulatory+arrest.">Transcranial Doppler study of intracranial circulatory arrest.</a> J Neurosurg. 71 (2), 195-201 (1989).</li><li>Zweifel, C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Reliability+of+the+blood+flow+velocity+pulsatility+index+for+assessment+of+intracranial+and+cerebral+perfusion+pressures+in+head-injured+patients.">Reliability of the blood flow velocity pulsatility index for assessment of intracranial and cerebral perfusion pressures in head-injured patients.</a> Neurosurg. 71 (4), 853-861 (2012).</li><li>Simm, R. F., De Aguiar, P. H. P., De Oliveira Lima, M., Paiva, B. L., Zuccarello, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Cerebral vasospasm: Neurovascular events after subarachnoid hemorrhage. , 75-76 (2013).</li><li>De Riva, N., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Transcranial+Doppler+pulsatility+index:+What+it+is+and+what+it+isn't.">Transcranial Doppler pulsatility index: What it is and what it isn't.</a> Neurocritic Care. 17 (1), 58-66 (2012).</li></ol>

PoC ultrasound is increasingly playing a vital role in the diagnosis and management of patients with acute organ dysfunction, as seen with RUSH and FAST exams. However, when evaluating cerebral function, to date there is little published guidance for clinicians seeking to perform PoC TCCD. 
To develop this PoC protocol, we chose to adapt TCCD rather than TCD imaging. In contrast to traditional TCD, TCCD combines B-mode and color Doppler, allowing for angle correction that results in more acc...

First described by Aaslid et al. in 1982, transcranial Doppler (TCD) ultrasonography offered a method to evaluate intracranial blood flow and velocity1. Later, transcranial color-coded duplex ultrasound (TCCD) was developed to allow color-coded visualization of intracerebral vasculature. This permits TCCD to partly overcome a limitation of TCD: angle dependence. Specifically, as a result of Doppler shift, measurements of blood flow velocity are most accurate if the angle of the ultrasound beam and the axis of the vessel are between 0-30 degrees2. While flow velocity measurements in TCD assume an angle close to zero, TCCD allows visualization of the angle of insonation and thus angle-corrected velocity measurements3.
TCCD includes several Doppler measurements including but not limited to: pulsatility index (PI), mean flow velocities (MFV), and or time-adjusted velocity (TAV)4. Using these measurements, TCCD permits non-invasive screening for several important conditions including vasospasm, increased intracranial pressure (ICP), and cerebral circulatory arrest, each of which manifests with a unique hemodynamic and sonographic signature5.
Firstly, in the context of cerebral vasospasm following subarachnoid hemorrhage (aneurysmal or traumatic), TCCD provides real-time visualization of intracranial blood flow, allowing for the detection of narrowing or constriction of cerebral arteries. By measuring MFV (defined as end-diastolic velocity + 1/3(peak systolic velocity + end diastolic velocity)6, clinicians can quantify the severity of vasospasm up to 2.5 days prior to the onset of symptoms7. Concurrently, by measuring PI (defined as peak systolic velocity - end diastolic velocity)/mean velocity), one can detect elevated values (&#62;1.2)7. Elevated values in turn suggest increased cerebrovascular resistance, highlighting the compromised distal perfusion associated with distal vessel vasospasm7or increased intracranial&#160;pressure. The combined use of TCCD, PI, and MFV facilitates early detection and monitoring of vasospasm, enabling prompt interventions to prevent ischemic injury and improve patient outcomes.
Second, in cases of increased ICP, cerebrovascular dynamics can be assessed through PI and MFV. PI and MFV reflect changes in cerebral blood flow and vascular resistance, both of which are impacted by elevations in ICP. Increased ICP may result in elevated PI values due to impaired cerebrovascular compliance, while decreased MFV indicates reduced cerebral perfusion secondary to elevated intracranial pressures4. Monitoring these parameters allows clinicians to gauge the severity of ICP elevation, guide treatment decisions, and assess the response to interventions aimed at lowering ICP.
Third, in the event of cerebral circulatory arrest, PI and MFV assessments play a critical role in confirming the cessation of cerebral blood flow. Rapid identification of cerebral circulatory arrest using TCCD and hemodynamic parameters is essential for initiating time-sensitive interventions, such as advanced neurocritical care measures, to restore cerebral perfusion if detected in a timely manner.
In summary, TCCD offers a non-invasive bedside tool to screen for cerebral vasospasm, increased ICP, and cerebral circulatory arrest. By providing real-time visualization and quantification of cerebral hemodynamics, TCCD enables clinicians to diagnose, monitor, and manage these critical neurological conditions, with potential for improving patient outcomes and reducing morbidity and mortality. But despite the known diagnostic value of transcranial ultrasound, point-of-care utilization of TCCD in critical care medicine remains variable, in part because training in this modality across hospitals is still inconsistent due to a lack of standardized training and education.
To address these gaps, this article proposes a TCCD image acquisition protocol in adults that can be used at the point-of-care (PoC). In general, a PoC ultrasound is one that is performed and interpreted by a patient&#39;s primary treating provider8. This is in contrast to a consultative ultrasound which is requested by a patient&#39;s primary treating provider but performed by a separate specialist team. Whereas consultative TCD or TCCD typically includes Doppler interrogation of multiple cerebral arteries, this PoC protocol centers on selective interrogation of the middle cerebral artery (MCA) for two reasons: (1) the MCA is typically the easiest branch of the Circle of Willis to insonate with TCCD and (2) The MCA is responsible for approximately 70% of the flow from the internal carotid artery, therefore analysis of the MCA can bring a good information about cerebral blood flow as a whole9.
This PoC TCCD protocol includes transducer selection and placement, sequence acquisition, and image optimization. Further, use of PoC TCCD will be discussed as a means of screening for the following three conditions: vasospasm, raised intra-cranial pressure, and progression of cerebral circulatory arrest.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Low Frequency Ultrasound Probe (C35xp)</td>
			<td>SonoSite (FujiFilm)</td>
			<td>P19617</td>
			<td></td>
		</tr>
		<tr>
			<td>SonoSite X-porte Ultrasound</td>
			<td>SonoSite (FujiFilm)</td>
			<td>P19220</td>
			<td></td>
		</tr>
		<tr>
			<td>Ultrasound Gel</td>
			<td>AquaSonic</td>
			<td>PLI 01-08</td>
			<td></td>
		</tr>
	</tbody>
</table>

point of care transcranial color-coded duplex ultrasound of the middle cerebral artery

In the assessment and management of many clinical problems, point-of-care (PoC) ultrasound is an emerging bedside tool. Transcranial color-coded duplex (TCCD) ultrasound can be valuable in multiple situations, including for patients who are unconscious or have an equivocal neurologic examination, as it helps rule in specific intracranial pathologies. Despite the known diagnostic value of transcranial ultrasound, its use in critical care medicine remains variable. This variability is partly due to inconsistent training across hospitals, stemming from a lack of standardized education and training. Additionally, the brain has often been overlooked in many critical care protocols, such as RUSH (Rapid Ultrasound for Shock and Hypotension) and FAST (Focused Assessment with Sonography in Trauma) exams. To address these gaps, this article proposes a protocol for PoC TCCD image acquisition in adults, detailing indications, limitations, transducer selection, placement, sequence acquisition, and image optimization. Furthermore, the use of PoC TCCD is discussed as a means of screening for three conditions: vasospasm, raised intracranial pressure, and progression of cerebral circulatory arrest.

This section will describe the analysis and interpretation of data obtained from the protocol above and its clinical utility. Figure 1 shows the physical location on the head where the TCCD is performed: in the transtemporal window. Figure 2 demonstrates this transtemporal window showing the ipsilateral MCA being interrogated with pulse-wave Doppler (PWD). With the PWD box placed at a depth of 45-65 mm18, a velocity profile should emerge ...

Point of Care Transcranial Color-Coded Duplex Ultrasound of the Middle Cerebral Artery

Transcranial ultrasound is an essential tool for monitoring patients with various neurological conditions. Although it is commonly used in a protocolized fashion in consultative studies, the brain has been overlooked in many protocols utilizing point-of-care ultrasound (PoCUS). This study proposes a PoCUS image acquisition protocol.

In the assessment and management of many clinical problems, point-of-care (PoC) ultrasound is an emerging bedside tool. Transcranial color-coded duplex ...

point-care-transcranial-color-coded-duplex-ultrasound-middle-cerebral

Research

JoVE Journal

Medicine

443 Views.  University of Southern California, Keck school of Medicine. Transcranial ultrasound is an essential tool for monitoring patients with various neurological conditions. Although it is commonly used in a protocolized fashion in consultative studies, the brain has been overlooked in many protocols utilizing point-of-care ultrasound (PoCUS). This study proposes a PoCUS image acquisition protocol.

Video: Point of Care Transcranial Color-Coded Duplex Ultrasound of the Middle Cerebral Artery

Mouse Model of Middle Cerebral Artery Occlusion

Stroke is the most common fatal neurological disease in the United States 1. The majority of strokes (88%) result from blockage of blood vessels in the brain (ischemic stroke) 2. Since most ischemic strokes (~80%) occur in the territory of middle cerebral artery (MCA) 3, many animal stroke models that have been developed have focused on this artery. The intraluminal monofilament model of middle cerebral artery occlusion (MCAO) involves the insertion of a surgical filament into the external carotid artery and threading it forward into the internal carotid artery (ICA) until the tip occludes the origin of the MCA, resulting in a cessation of blood flow and subsequent brain infarction in the MCA territory 4. The technique can be used to model permanent or transient occlusion 5. If the suture is removed after a certain interval (30 min, 1 h, or 2 h), reperfusion is achieved (transient MCAO); if the filament is left in place (24 h) the procedure is suitable as a model of permanent MCAO. This technique does not require craniectomy, a neurosurgical procedure to remove a portion of skull, which may affect intracranial pressure and temperature 6. It has become the most frequently used method to mimic permanent and transient focal cerebral ischemia in rats and mice 7,8. To evaluate the extent of cerebral infarction, we stain brain slices with 2,3,5-triphenyltetrazolium chloride (TTC) to identify ischemic brain tissue 9. In this video, we demonstrate the MCAO method and the determination of infarct size by TTC staining.

We demonstrate in the video a method for producing a middle cerebral artery occlusion in adult mice using an intraluminal monofilament. We also show how to evaluate the extent of cerebral infarction by 2,3,5-triphenyltetrazolium chloride (TTC) staining.

Stroke is the most common fatal neurological disease in the United States 1. The majority of strokes (88%) result from blockage of blood vessels in the ...

The Application Of Permanent Middle Cerebral Artery Ligation in the Mouse

Focal cerebral ischemia is among the most common type of stroke seen in patients. Due to the clinical significance there has been a prolonged effort to develop suitable animal models to study the events that unfold during ischemic insult. These techniques include transient or permanent, focal or global ischemia models using many different animal models, with the most common being rodents.
The permanent MCA ligation method which is also referred as pMCAo in the literature is used extensively as a focal ischemia model in rodents 1-6. This method was originally described for rats by Tamura et al. in 1981 7. In this protocol a craniotomy was used to access the MCA and the proximal regions were occluded by electrocoagulation. The infarcts involve mostly cortical and sometimes striatal regions depending on the location of the occlusion. This technique is now well established and used in many laboratories 8-13. Early use of this technique led to the definition and description of &#x201C;infarct core&#x201D; and &#x201C;penumbra&#x201D; 14-16, and it is often used to evaluate potential neuroprotective compounds 10, 12, 13, 17. Although the initial studies were performed in rats, permanent MCA ligation has been used successfully in mice with slight modifications 18-20 .
This model yields reproducible infarcts and increased post-survival rates. Approximately 80% of the ischemic strokes in humans happen in the MCA area 21 and thus this is a very relevant model for stroke studies. Currently, there is a paucity of effective treatments available to stroke patients, and thus there is a need for good models to test potential pharmacological compounds and evaluate physiological outcomes. This method can also be used for studying intracellular hypoxia response mechanisms in vivo. 
Here, we present the MCA ligation surgery in a C57/BL6 mouse. We describe the pre-surgical preparation, MCA ligation surgery and 2,3,5 Triphenyltetrazolium chloride (TTC) staining for quantification of infarct volumes.

Middle cerebral artery (MCA) ligation is a technique to study focal cerebral ischemia in animal models. In this method, the middle cerebral artery is exposed by craniotomy and ligated by cauterization. This method gives highly reproducible infarct volumes and increased post-operative survival rates compared to other methods available.

Focal cerebral ischemia is among the most common type of stroke seen in patients. Due to the clinical significance there has been a prolonged effort to ...

Utilizing a Cranial Window to Visualize the Middle Cerebral Artery During Endothelin-1 Induced Middle Cerebral Artery Occlusion

Creation of a cranial window is a method that allows direct visualization of structures on the cortical surface of the brain1-3. This technique can be performed in many locations overlying the rat cerebrum, but is most easily carried out by creating a craniectomy over the readily accessible frontal or parietal bones. Most frequently, we have used this technique in combination with the endothelin-1 middle cerebral artery occlusion model of ischemic stroke to quantify the changes in middle cerebral artery vessel diameter that occur with injection of endothelin-1 into the brain parenchyma adjacent to the proximal MCA4, 5. In order to visualize the proximal portion of the MCA during endothelin -1 induced MCAO, we use a technique to create a cranial window through the temporal bone on the lateral aspect of the rat skull (Figure 1). Cerebral arteries can be visualized either with the dura intact or with the dura incised and retracted. Most commonly, we leave the dura intact during visualization since endothelin-1 induced MCAO involves delivery of the vasoconstricting peptide into the brain parenchyma. This bypasses the need to incise the dura directly over the visualized vessels for drug delivery. This protocol will describe how to create a cranial window to visualize cerebral arteries in a step-wise fashion, as well as how to avoid many of the potential pitfalls pertaining to this method.

This article describes a method for visualizing rat cerebral arteries through a cranial window using temporal craniectomy in order to view proximal portions of the middle cerebral artery (Figure 1). This versatile method can be combined with various techniques of drug delivery to measure cerebral artery reactivity in vivo.

Creation of a cranial window is a method that allows direct visualization of structures on the cortical surface of the brain1-3. This technique can be ...

Modeling Stroke in Mice: Permanent Coagulation of the Distal Middle Cerebral Artery

Stroke is the third most common cause of death and a main cause of acquired adult disability in developed countries. Only very limited therapeutical options are available for a small proportion of stroke patients in the acute phase. Current research is intensively searching for novel therapeutic strategies and is increasingly focusing on the sub-acute and chronic phase after stroke because more patients might be eligible for therapeutic interventions in a prolonged time window. These delayed mechanisms include important pathophysiological pathways such as post-stroke inflammation, angiogenesis, neuronal plasticity and regeneration. In order to analyze these mechanisms and to subsequently evaluate novel drug targets, experimental stroke models with clinical relevance, low mortality and high reproducibility are sought after. Moreover, mice are the smallest mammals in which a focal stroke lesion can be induced and for which a broad spectrum of transgenic models are available. Therefore, we describe here the mouse model of transcranial, permanent coagulation of the middle cerebral artery via electrocoagulation distal of the lenticulostriatal arteries, the so-called &#8220;coagulation model&#8221;. The resulting infarct in this model is located mainly in the cortex; the relative infarct volume in relation to brain size corresponds to the majority of human strokes. Moreover, the model fulfills the above-mentioned criteria of reproducibility and low mortality. In this video we demonstrate the surgical methods of stroke induction in the &#8220;coagulation model&#8221; and report histological and functional analysis tools.

Various murine models of middle cerebral artery occlusion (MCAO) are widely used in experimental brain research. Here, we demonstrate the model of transcranial permanent distal MCAO which produces consistent cortical infarction of a size corresponding to damage imposed by the majority of human ischemic strokes.

Stroke is the third most common cause of death and a main cause of acquired adult disability in developed countries. Only very limited therapeutical ...

Point-of-Care Lung Ultrasound in Adults: Image Acquisition

Consultative ultrasound performed by radiologists has traditionally not been used for imaging the lungs, as the lungs&#39; air-filled nature normally prevents direct visualization of the lung parenchyma. When showing the lung parenchyma, ultrasound typically generates a number of non-anatomic artifacts. However, over the past several decades, these artifacts have been studied by diagnostic point-of-care ultrasound (POCUS) practitioners, who have identified findings that have value in narrowing the differential diagnoses of cardiopulmonary dysfunction. For instance, in patients presenting with dyspnea, lung POCUS is superior to chest radiography (CXR) for the diagnosis of pneumothorax, pulmonary edema, lung consolidations, and pleural effusions. Despite its known diagnostic value, the utilization of lung POCUS in clinical medicine remains variable, in part because training in this modality across hospitals remains inconsistent. To address this educational gap, this narrative review describes lung POCUS image acquisition in adults, including patient positioning, transducer selection, probe placement, acquisition sequence, and image optimization.

Point-of-care ultrasound (POCUS) of the lungs provides quick answers in rapidly changing clinical scenarios. We present an efficient and informative protocol for image acquisition for use in acute care settings.

Consultative ultrasound performed by radiologists has traditionally not been used for imaging the lungs, as the lungs&#39; air-filled nature normally ...

Point-of-Care Ultrasound: A Review of Ultrasound Parameters for Predicting Difficult Airways

Airway management remains a crucial part of perioperative care. The conventional approach to assessing potentially difficult airways emphasizes the LEMON method, which looks for and evaluates the Mallampati classification, signs of obstruction, and neck mobility. Clinical findings help predict a higher likelihood of difficult tracheal intubation, but no clinical result reliably excludes difficult intubation. Ultrasound as an adjunct to clinical examination can provide the clinician with a dynamic anatomical airway assessment, which is impossible with clinical examination alone. In the hands of anesthesiologists, ultrasound is becoming more popular in the perioperative period. This method is particularly applicable for identifying proper endotracheal tube positioning in specific patient populations, such as those who are morbidly obese and patients with head and neck cancer or trauma. The focus is on identifying the normal anatomy, correctly positioning the endotracheal tube, and refining the parameters that predict difficult intubation. Several ultrasound measurements are clinical indicators of difficult direct laryngoscopy in the literature. A meta-analysis revealed that the distance from the skin to the epiglottis (DSE) is most associated with a difficult laryngoscopy. An ultrasound of the airway could be applied in routine practice as an adjunct to the clinical examination. A full stomach, rapid sequence intubation, gross visual anatomical abnormalities, and restricted neck flexibility prevent using ultrasound to assess the airway. The airway evaluation is performed with a linear array transducer of 12-4 MHz, with the patient in the supine position, with no pillow, and with the head and neck in a neutral position. The central axis of the neck is where the ultrasound parameters are measured. These image acquisitions guide the standard ultrasound examination of the airway.

A point-of-care ultrasound (POCUS) is a simple, non-invasive, and portable tool that enables dynamic airway assessment. Several studies have attempted to determine the role of ultrasound parameters as an adjunct to clinical examination in predicting difficult laryngoscopies.

Airway management remains a crucial part of perioperative care. The conventional approach to assessing potentially difficult airways emphasizes the LEMON ...

Optic Nerve Sheath Point of Care Ultrasound: Image Acquisition

The goal of this protocol is to develop a standardized method for acquiring images of the optic nerve sheath and measuring the optic nerve sheath diameter (ONSD). Diagnostic ultrasound of the ONSD to detect intracranial hypertension has traditionally faced many problems because of methodologic discrepancies. Due to inconsistencies in the measuring techniques, the potential for ONSD to become a non-invasive bedside monitoring tool for ICP has been hampered. However, establishing a transparent, consistent methodology for measuring the ONSD would support its use as a valid and reliable method of identifying intracranial hypertension. This is important as it has both high sensitivity and specificity in acute care settings. This narrative review describes ONSD POCUS image acquisition, including patient positioning, transducer selection, probe placement, the acquisition sequence, and image optimization. Further, visual aids are provided to assist in real-time during image acquisition. This method should be considered for patients for whom there are concerns regarding intracranial hypertension but who do not have an intracranial monitor in place.

Point-of-care ultrasound (POCUS) of the optic nerve sheath diameter (ONSD) has been shown to be useful in identifying patients with increased intracranial pressure (ICP). However, the non-standardized technique for this POCUS has hampered its use. We present a standardized image acquisition protocol for use in the acute care setting.

The goal of this protocol is to develop a standardized method for acquiring images of the optic nerve sheath and measuring the optic nerve sheath diameter ...

Imaging the Abdominal Aorta with Point-of-Care Ultrasound

An Approach to Point-Of-Care Ultrasound Evaluation of the Abdominal Aorta

Disorders of the abdominal aorta, including aneurysms and dissection, have potentially high rates of morbidity and mortality. While computed tomography (CT) is the current gold standard to image the abdominal aorta, the process of obtaining a CT may be time-consuming, requires the use of intravenous contrast dye, and involves exposure to ionizing radiation. Point-of-care Ultrasound (POCUS) can be performed at the bedside and has excellent sensitivity and specificity for the diagnosis of abdominal aortic aneurysm and excellent specificity for the diagnosis of abdominal aortic dissection. Additionally, POCUS is non-invasive, cost-effective, lacks ionizing radiation, requires no intravenous contrast dye, and can be performed without taking the patient from a critical care area. Screening for abdominal aortic aneurysm (AAA) can be done in primary care settings as well. 
This article will review the approach to POCUS of the abdominal aorta to evaluate such critical pathology. In this paper, we will review the sonographic anatomy of the abdominal aorta as well as the choice of the ultrasound probe, description of POCUS image acquisition, and some pearls and pitfalls of using POCUS to aid in the diagnosis of potentially life-threatening abdominal aortic pathology.

Author Spotlight: Using Point-of-Care Ultrasound for Comprehensive Evaluation of the Abdominal Aorta

This protocol reviews the steps to image the abdominal aorta with point-of-care ultrasound. We discuss image acquisition, troubleshooting imaging pitfalls and artifacts, and the recognition of life-threatening abdominal aortic pathology.

Disorders of the abdominal aorta, including aneurysms and dissection, have potentially high rates of morbidity and mortality. While computed tomography ...

Ultrasound in Evaluating Diaphragm Dysfunction and Monitoring Treatment

Measuring Diaphragm Thickness and Function Using Point-of-Care Ultrasound

The diaphragm is the main component of the respiratory muscle pump. Diaphragm dysfunction can cause dyspnea and exercise intolerance, and predisposes affected individuals to respiratory failure. In mechanically ventilated patients, the diaphragm is susceptible to atrophy and dysfunction through disuse and other mechanisms. This contributes to failure to wean and poor long-term clinical outcomes. Point-of-care ultrasound provides a valid and reproducible method for evaluating diaphragm thickness and contractile activity (thickening fraction during inspiration) that can be readily employed by clinicians and researchers alike. This article presents best practices for measuring diaphragm thickness and quantifying diaphragm thickening during tidal breathing or maximal inspiration. Once mastered, this technique can be used to diagnose and prognosticate diaphragm dysfunction, and guide and monitor response to treatment over time in both healthy individuals and acute or chronically ill patients.

Author Spotlight: Unraveling the Impact of Mechanical Ventilation on Diaphragm Function and Patient Outcomes 

Diaphragm thickness and function can be assessed in healthy individuals and critically ill patients using point-of-care ultrasound. This technique offers an accurate, reproducible, feasible, and well-tolerated method for evaluating diaphragm structure and function.

The diaphragm is the main component of the respiratory muscle pump. Diaphragm dysfunction can cause dyspnea and exercise intolerance, and predisposes ...