Name: point-of-care ultrasound: a review of ultrasound parameters for predicting difficult airways
Uploaded: 2023-04-07T13:30:00
Description: Watch this Scientific Journal Video about Point-of-Care Ultrasound: A Review of Ultrasound Parameters for Predicting Difficult Airways at JoVE.com

This study was supported, in part, by the National Institutes of Health/National Cancer Institute (Bethesda, Maryland) Cancer Support Grant P30 CA008748.

This scanning protocol is for clinical training and has not been published elsewhere. The ultrasound images were obtained from a volunteer and de-identified. As per the institutional guidelines, this protocol is beyond the Common Rule and FDA definition of the human research subject, and formal IRB approval is not required.
1. Transducer and image optimization
<ol>
	<li>Use a linear array 12-4 MHz transducer. This is a high-frequency transducer for superficial imaging struct...

<ol>
	<li>Apfelbaum, J. L., 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=American+Society+of+Anesthesiologists+Practice+Guidelines+for+Management+of+the+Difficult+Airway.">American Society of Anesthesiologists Practice Guidelines for Management of the Difficult Airway.</a> Anesthesiology. 136 (1), 31-81 (2022).</li><li>Ji, S. 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=Correlation+between+modified+LEMON+score+and+intubation+difficulty+in+adult+trauma+patients+undergoing+emergency+surgery.">Correlation between modified LEMON score and intubation difficulty in adult trauma patients undergoing emergency surgery.</a> World Journal of Emergency Surgery. 13, 33 (2018).</li><li>Hall, E. A., Showaihi, I., Shofer, F. S., Panebianco, N. L., Dean, A. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ultrasound+evaluation+of+the+airway+in+the+ED:+A+feasibility+study.">Ultrasound evaluation of the airway in the ED: A feasibility study.</a> Critical Ultrasound Journal. 10 (1), 3 (2018).</li><li>Chou, H. -. 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=Tracheal+rapid+ultrasound+exam+(T.R.U.E.)+for+confirming+endotracheal+tube+placement+during+emergency+intubation.">Tracheal rapid ultrasound exam (T.R.U.E.) for confirming endotracheal tube placement during emergency intubation.</a> Resuscitation. 82 (10), 1279-1284 (2011).</li><li>Sotoodehnia, M., Rafiemanesh, H., Mirfazaelian, H., Safaie, A., Baratloo, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ultrasonography+indicators+for+predicting+difficult+intubation:+A+systematic+review+and+meta-analysis.">Ultrasonography indicators for predicting difficult intubation: A systematic review and meta-analysis.</a> BMC Emergency Medicine. 21 (1), 76 (2021).</li><li>Prasad, 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=Comparison+of+sonography+and+computed+tomography+as+imaging+tools+for+assessment+of+airway+structures.">Comparison of sonography and computed tomography as imaging tools for assessment of airway structures.</a> Journal of Ultrasound in Medicine. 30 (7), 965-972 (2011).</li><li>Andruszkiewicz, P., Wojtczak, J., Sobczyk, D., Stach, O., Kowalik, I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effectiveness+and+validity+of+sonographic+upper+airway+evaluation+to+predict+difficult+laryngoscopy.">Effectiveness and validity of sonographic upper airway evaluation to predict difficult laryngoscopy.</a> Journal of Ultrasound in Medicine. 35 (10), 2243-2252 (2016).</li><li>Adhikari, S., 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=Pilot+study+to+determine+the+utility+of+point-of-care+ultrasound+in+assessing+difficult+laryngoscopy.">Pilot study to determine the utility of point-of-care ultrasound in assessing difficult laryngoscopy.</a> Academic Emergency Medicine. 18 (7), 754-758 (2011).</li><li>Ezri, 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=Prediction+of+difficult+laryngoscopy+in+obese+patients+by+ultrasound+quantification+of+anterior+neck+soft+tissue.">Prediction of difficult laryngoscopy in obese patients by ultrasound quantification of anterior neck soft tissue.</a> Anaesthesia. 58 (11), 1111-1114 (2003).</li><li>Yadav, N. K., Rudingwa, P., Mishra, S. K., Pannerselvam, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ultrasound+measurement+of+anterior+neck+soft+tissue+and+tongue+thickness+to+predict+difficult+laryngoscopy+-+An+observational+analytical+study.">Ultrasound measurement of anterior neck soft tissue and tongue thickness to predict difficult laryngoscopy - An observational analytical study.</a> Indian Journal of Anaesthesia. 63 (8), 629-634 (2019).</li><li>Martinez-Garcia, A., Guerrero-Orriach, J. L., Pino-Galvez, M. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ultrasonography+for+predicting+difficult+laryngoscopy.+Getting+closer.">Ultrasonography for predicting difficult laryngoscopy. Getting closer.</a> Journal of Clinical Monitoring and Computing. 35 (2), 269-277 (2020).</li><li>Carsetti, A., Sorbello, M., Adrario, E., Donati, A., Falcetta, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Airway+ultrasound+as+predictor+of+difficult+direct+laryngoscopy:+A+systematic+review+and+meta-analysis.">Airway ultrasound as predictor of difficult direct laryngoscopy: A systematic review and meta-analysis.</a> Anesthesia and Analgesia. 134 (4), 740-750 (2022).</li><li>Petrisor, C., Szabo, R., Constantinescu, C., Prie, A., Hagau, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ultrasound-based+assessment+of+hyomental+distances+in+neutral,+ramped,+and+maximum+hyperextended+positions,+and+derived+ratios,+for+the+prediction+of+difficult+airway+in+the+obese+population:+A+pilot+diagnostic+accuracy+study.">Ultrasound-based assessment of hyomental distances in neutral, ramped, and maximum hyperextended positions, and derived ratios, for the prediction of difficult airway in the obese population: A pilot diagnostic accuracy study.</a> Anaesthesiology Intensive Therapy. 50 (2), 110-116 (2018).</li><li>Reddy, P. B., Punetha, P., Chalam, K. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ultrasonography+-+A+viable+tool+for+airway+assessment.">Ultrasonography - A viable tool for airway assessment.</a> Indian Journal of Anaesthesia. 60 (11), 807-813 (2016).</li><li>Wu, J., Dong, J., Ding, Y., Zheng, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Role+of+anterior+neck+soft+tissue+quantifications+by+ultrasound+in+predicting+difficult+laryngoscopy.">Role of anterior neck soft tissue quantifications by ultrasound in predicting difficult laryngoscopy.</a> Medical Science Monitor. 20, 2343-2350 (2014).</li><li>Pinto, 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=Predicting+difficult+laryngoscopy+using+ultrasound+measurement+of+the+distance+from+skin+to+the+epiglottis.">Predicting difficult laryngoscopy using ultrasound measurement of the distance from skin to the epiglottis.</a> Journal of Critical Care. 33, 26-31 (2016).</li><li>Falcetta, S., 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=Evaluation+of+two+neck+ultrasound+measurements+as+predictors+of+difficult+direct+laryngoscopy:+A+prospective+observational+study.">Evaluation of two neck ultrasound measurements as predictors of difficult direct laryngoscopy: A prospective observational study.</a> European Journal of Anaesthesiology. 35 (8), 605-612 (2018).</li><li>Chalumeau-Lemoine, L., 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=Results+of+short-term+training+na&#239;ve+physicians+in+focused+general+ultrasonography+in+an+intensive-care+unit.">Results of short-term training na&#239;ve physicians in focused general ultrasonography in an intensive-care unit.</a> Intensive Care Medicine. 35 (10), 1767-1771 (2009).</li></ol>

Ultrasound of the airway is an effective methodology to examine the airway. The goal is to incorporate airway examination into daily practice to give additive value to the standard pre-anesthetic assessment of the airway before the induction of anesthesia.
It is best to start the scanning protocol from the submandibular space with the transducer positioned along the long axis of the body - the sagittal plane. From there, the transducer is turned in the transverse position along the midline and...

Airway management is a crucial part of a patient&#39;s perioperative care and is an essential skill for an anesthesiologist. Failure to secure a proper airway can result in unplanned intensive care admissions and complications, prolonged hospital stays, and an increased risk of brain damage and death. The American Society of Anesthesiologists (ASA) 2022 difficult airway task force updated the definition of a difficult airway to include the following: difficult mask ventilation, a difficult laryngoscopy view, a high number of intubation attempts, the use of advanced airway adjuncts, and difficult extubation or ventilation1. The visual assessment of the airway before intubation includes looking for, evaluating, and allocating a Mallampati score, observing for signs of obstruction, and assessing the neck mobility. This is commonly known as the LEMON method. Additional assessments include radiographic, oropharyngeal, or external anatomic airway structure assessments and the upper lip bite test2.&#160;No method is without limitations as a predictor of significant intubation difficulty. These many quality assessments may explain why the incidence of difficult airways varies from 5% to 22% and the positive predictive value (PPV) is low. A recent meta-analysis showed a low prevalence of difficult intubation in patients with a Mallampati score of III or IV, making the Mallampatti scoring system less sensitive and specific than measured ultrasound parameters3. Images of the airway provided on ultrasound are comparable to radiography, rendering it an appealing alternative. Ultrasound of the airway has been gaining momentum as an adjunct in airway management since point-of-care ultrasound protocols were introduced and shown to be supported by clinical data based on identifying endotracheal tube placement in trauma patients4. Ultrasound provides the clinician with a dynamic anatomical assessment, which is impossible with clinical examination alone.
Studies indicate the added value of specific ultrasound parameters in determining a difficult laryngoscopy visualization. The feasibility of point-of-care ultrasound (POCUS) for airway management in the perioperative setting is still an area of great interest. Ultrasound reliably images all the structures visualized by CT, and infrahyoid airway structures agree well with the parameters measured by CT5. Various ultrasound measurements at different levels of the neck have been studied. The following measurements correlate with difficult direct laryngoscopy: (1) the hyomental distance (HMD); (2) the thyrohyoid membrane (THM); (3) the distance from the skin to the epiglottis (DSE); (4) the distance from the skin to the hyoid bone (SHB); and (5) the distance from the skin to the vocal cords (SVC). This method is suitable for general populations and specific populations, such as those with obesity. A full stomach, rapid sequence intubation, gross visual anatomical abnormalities, and restricted neck mobility from different causes preclude using ultrasound to assess the airway.
This narrative review discusses the significant ultrasound parameters in the POCUS of the airway and supplies training suggestions that can be used in everyday practice. Ultrasound is simple, portable, easy, and has a short learning curve.
Sound above a frequency of 20 MHz is called ultrasound, and medical imaging uses 2-15 MHz. Ultrasound waves are transmitted and received by an ultrasound transducer, commonly called an ultrasound probe. The resistance of the ultrasound wave traveling through tissue is called the acoustic impedance. Ultrasound waves reflect from the tissue-air interface back to the transducer, and different tissues have different acoustic impedances. Bone gives a strong echo, meaning it is referred to as being hyperechoic and appears white. In addition, bone absorbs the ultrasound waves, and nothing passes beyond it. This phenomenon is described as acoustic shadowing. Airway structures that contain cartilage create a small echo; they are described as hypoechoic structures and appear dark on the ultrasound image. As calcifications develop with aging, these structures appear more echogenic5.&#160;A more heterogenic appearance is seen with muscle and connective tissue. Glandular tissue appears brighter, meaning this tissue is hyperechoic. It is essential to understand the air-tissue border concept. The ultrasound waves do not travel through the air but return to the transducer, creating a strong reflection. The returning echo signal is a dispersion artifact - a reverberation causing multiple white lines. The ultrasound beam at the air-mucosa interface creates a bright white line. Denser tissue appears brighter on the screen, and the structures beyond cannot be observed. Clinically, only the tissue from the skin to the anterior luminal surface of solid tissue is visualized. The posterior wall of the pharynx and larynx cannot be visualized. Acoustic shadowing reflects the ultrasound beams returning to the probe6.
The ultrasound transducers include a curved low-frequency (C5-1 MHz) transducer, a high-frequency linear array (L12-4 MHz), (L12-5) MHz, or&#160;(L13-6 MHz) transducer. The airway structures are superficial within 2-3 cm from the skin but are deeper in obese patients due to the increased anterior neck fat tissue. The curved low-frequency C5-1 MHz transducer displays a broader field of view for a better submandibular view. If only one transducer is available, then the high-frequency linear array performs all ultrasound examinations relevant to the airway assessment. The transducer must have complete contact with the skin. A generous amount of conductive gel is needed to maintain the skin contact. In males, it is challenging to prevent air from being trapped between the skin and the transducer due to the prominent thyroid cartilage. In this instance, minimal caudal and cranial adjustments can be used to optimize the image.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Gel-Lubricant jelly</td>
			<td>MediChoice</td>
			<td>13143 gram, LUB Sterile</td>
			<td>Bacteriostatic,water soluble-alcohol free.</td>
		</tr>
		<tr>
			<td>Philips SPARQ Point of Care System</td>
			<td>Philips</td>
			<td>Transducer L12-4 MHz</td>
			<td>Broadband linear. 128elements. 38.4 mm.</td>
		</tr>
	</tbody>
</table>

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.

This paper aims to provide significant ultrasound parameters that are predictive of a difficult laryngoscopy. To date, 30 studies have analyzed several different ultrasound parameters. Two meta-analyses have identified the five most studied parameters that significantly differ between easy and difficult direct laryngoscopy views and have higher sensitivity and specificity than the classic Mallampatti classification12. This narrative review follows the scanning protocols from the studies shown in <...

Watch this Scientific Journal Video about Point-of-Care Ultrasound: A Review of Ultrasound Parameters for Predicting Difficult Airways at JoVE.com

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

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 ...

The ultrasound image acquisition can guide the standard ultrasound assessment of the airway. Ultrasound can provide the clinician with a dynamic anatomical airway assessment, which is not possible with clinical examination alone. The technique is simple and one can practice it on oneself and colleagues.It is possible to achieve competency after about 20 exams. Begin by asking the patient to lie down in a supine position without a pillow. To ensure standardization and best measurements, ask the patient to maintain the head and neck in a neutral position.Ask the patient to rest their tongue on the lower incisors. For consistency, the tongue should remain in the same position throughout the ultrasound examination. Once the patient is positioned correctly, apply a gel medium on the transducer to ensure there is no air between the skin and the transducer.Place the transducer transversely on the anterior neck of the patient with minimal pressure, while preserving skin contact. Then place the transducer midline on the central axis in the transverse position. And beginning from the submandibular space with slow fine movements, move the transducer cordally.For a submandibular image, place the transducer longitudinally in the submental space along the body's central axis. Click on freeze, followed by clicking on measure, then measure the distance from the outer border of the mentum to the hyoid bone. As the value of the distance in centimeters pops up on the screen, click on acquire.Rotate the transducer in the transverse position and place it over the central axis of the neck. Manipulate the transducer cordally with fine slow movements for visualizing the structures of interest. To visualize the thyroid hyoid membrane or THM, palpate the thyroid cartilage and the hyoid bone, and place the transducer in between the transverse position, while ensuring it stays in the central axis of the neck.Sequentially, click on freeze and measure before measuring the distance from the skin to the anterior border of the epiglottis in the center. As the distance in centimeters pops up on the screen, click on acquire. Then move the transducer one centimeter to the right and as demonstrated previously, repeat the measurement.Once the distance value appears on the screen, acquire the data. Next, move the transducer one centimeter to the left of the center and repeat the process of acquiring the measurement. Average the three measurements to obtain the THM.Keep the transducer in the same position and stay in the next central axis to view the hypoechoic curvilinear epiglottis as a dark space. Click on freeze, followed by clicking on measure. Then measure the distance from the skin to the center of the bright white line.As the value of the distance in centimeters pops up on the screen, click on acquire. Move the probe one centimeter left of the midline and acquire the measurement again. Then move the transducer one centimeter to the right of the midline to acquire the measurement for the third time.Average the three measurements to obtain the distance from the skin to the epiglottis or DSC. Angle the transducer tail about 20 degrees down. Palpate the hyoid bone and place the transducer directly over the hyoid bone while keeping the probe in the central axis of the neck.Sequentially, click on freeze and measure. Measure the distance from the skin to the center of the hyoid bone, seen as a bright echogenic line, curved upside down above the hypoechoic shadow and acquire the data. Move the probe one centimeter lateral to the midline on the left to acquire one more measurement.For the third measurement, move the transducer one centimeter to the right of the midline and average the three measurements to obtain the distance from the skin to the hyoid bone or SHB. To measure the distance from the skin to the vocal cords or SVC, place the transducer transversely over the thyroid cartilage while staying in the central axis of the neck. Click on freeze followed by clicking on measure.Then measure the distance from the skin to the upper border of the right vocal cord and acquire the data. Repeat the same measurement on the left vocal cord and average the two measurements to obtain the SVC. In 30 studies, several different ultrasound parameters predictive of a difficult laryngoscopy were analyzed.Two meta-analyses identified the five most studied parameters that significantly differed between easy and difficult direct laryngoscopy views. In the neutral position, an HMD value of 3.4 to 4.5 centimeters was associated with difficult direct laryngoscopy. The parameter had a sensitivity and a specificity of 100%and 71.4%respectively, and was predictive in general and obese populations.A TMH value higher than 2.8 centimeters predicted a difficult laryngoscopy. This parameter had a sensitivity of 64.7%and a specificity of 77.1%A meta-analysis found DSE as the parameter correlating the most with difficult direct laryngoscopy. The average DSE value greater than 2 to 2.5 centimeters had a positive predictive value of about 30%to 50%while the negative predictive value of the parameter ranged from 95%to 97%An SHB greater than 1.28 centimeters correlated with difficult direct laryngoscopy.The parameter had a sensitivity and specificity of 85.7%and 85.1%respectively. In difficult direct laryngoscopies, SVC measurements from about 0.9 to 1.3 centimeters were reported. Maintaining the head in the neutral position and resting the tongue on the lower incisors is important.The transducer must rest on the central axis of the neck and should be moved slowly. Ultrasound can be incorporated into daily practice as an adjunct to the clinical examination of the airway.

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Point-Of-Care Ultrasound Screening for Proximal Lower Extremity Deep Venous Thrombosis

Acute lower extremity deep venous thrombosis (DVT) is a serious vascular disorder that requires accurate and early diagnosis to prevent life-threatening sequelae. While whole leg compression ultrasound with color and spectral Doppler is commonly performed in radiology and vascular labs, point-of-care ultrasound (POCUS) is becoming more common in the acute care setting. Providers appropriately trained in focused POCUS can perform a rapid bedside examination with high sensitivity and specificity in critically ill patients. This paper describes a simplified yet validated approach to POCUS by describing a three-zone protocol for lower extremity DVT POCUS image acquisition. The protocol explains the steps in obtaining vascular images at six compression points in the lower extremity. Beginning at the level of the proximal thigh and moving distally to the popliteal space, the protocol guides the user through each of the compression points in a stepwise manner: from the common femoral vein to the femoral and deep femoral vein bifurcation, and, finally, to the popliteal vein. Further, a visual aid is provided that may assist providers during real-time image acquisition. The goal in presenting this protocol is to help make proximal lower extremity DVT exams more accessible and efficient for POCUS users at the patient&#39;s bedside.

Traditionally, lower extremity deep venous thrombosis (DVT) is diagnosed by radiology-performed venous duplex ultrasound. Providers appropriately trained in focused point-of-care ultrasound (POCUS) can perform a rapid bedside examination with high sensitivity and specificity in critically ill patients. We describe the scanning technique for focused POCUS DVT lower extremity examination.

Acute lower extremity deep venous thrombosis (DVT) is a serious vascular disorder that requires accurate and early diagnosis to prevent life-threatening ...

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 ...

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 ...

Gastric Ultrasound Technique for Mitigating Peri-Procedural Aspiration Risk

Gastric Point of Care Ultrasound in Adults: Image Acquisition and Interpretation

Over the past two decades, diagnostic point-of-care ultrasound (POCUS) has emerged as a rapid and non-invasive bedside tool for addressing clinical inquiries related to gastric content. One emerging concern pertains to patients about to undergo sedation and/or endotracheal intubation: the elevated risk of aspiration from the patient&#39;s stomach contents. Aspiration of gastric contents into the lungs poses a serious and potentially life-threatening complication. This occurs more frequently when the stomach is considered &#34;full&#34; and can be affected by the techniques employed for airway management, making it potentially preventable. To mitigate the risk of peri-procedural aspiration, two distinct medical specialties (anesthesiology and critical care medicine) have independently developed techniques to utilize ultrasonography for identifying patients requiring &#34;full stomach&#34; precautions. Due to these separate specialties, the work of each group remains relatively unfamiliar outside its respective field. This article presents descriptions of both techniques for gastric ultrasound. Furthermore, it explains how these approaches can complement each other when one of them falls short. Regarding image acquisition, the article covers the following topics: indications and contraindications, selection of the appropriate probe, patient positioning, and troubleshooting. The article also delves into image interpretation, complete with example images. Additionally, it demonstrates how one of the two techniques can be employed to estimate gastric fluid volume. Lastly, the article briefly discusses medical decision-making based on the findings of this examination.

Author Spotlight: Point-of-Care Ultrasound for Gastric Content Assessment and Risk Stratification in Perioperative Care 

This protocol introduces two methods for image acquisition in gastric ultrasonography. Additionally, tips are provided for interpreting this information to assist in medical decision-making.

Over the past two decades, diagnostic point-of-care ultrasound (POCUS) has emerged as a rapid and non-invasive bedside tool for addressing clinical ...

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 ...

Probe Selection and Machine Presets for Point-of-Care Ultrasound of the Abdominal Aorta

To perform a point of care ultrasound evaluation of the abdominal aorta, select a 2.5 to 3.5 megahertz curvilinear probe, which provides the best visualization for most adults. Alternatively, use the phased array probe of 1 to 5 megahertz, commonly called cardiac probe, which is typically used for echocardiography. Use the abdominal preset on the machine regardless of the probe used.Set the mode to B mode or two-dimensional gray scale and the depth to 20 centimeters. Adjust the depth once the aorta is visualized to keep the aorta in the midfield of the screen. Choose a lower frequency range for patients with a high body mass index to improve image acquisition.

Imaging the Abdominal Aorta in the Transverse Plane Using Point-of-Care Ultrasound

To begin scanning, position the patient's supine with the abdomen exposed. Hip flexion, if tolerated by the patient, relaxes the abdominal muscles and may improve image acquisition. Apply ultrasound gel to the transducer.Orient the transducer and the transverse plane with the indicator toward the patient's right. Ensure that the indicator position matches the one displayed on the screen. Place the transducer just distal to the patient's xiphoid process and apply light pressure to visualize the anterior aspect of the vertebra with its hyperechoic shadow casting arch.Slide the transducer coddly until the celiac trunk is visualized. The celiac trunk is short and quickly bifurcates into the hepatic artery and splenic artery, which together form the seagull sign. Capture these images for later review by clicking the button on the system that records clips.Slide the transducer coddly to view the superior mesenteric artery or SMA. Coming off the anterior aorta, SMA follows a path parallel to the aorta to course inferiorly. The splenic vein courses anterior to the SMA and the left renal vein courses between the SMA and the aorta.Measure the AP diameter of the suprarenal aorta by optimizing a live image of the aorta in this location, and then pressing the system's freeze button. Press caliper or measure and move the track ball or touch pad of the system to the outer edge of the anterior wall, the adventitia and click select. Next, move the track ball or touch pad again to the outer edge of the posterior wall and click select.Wait for the system to generate a measurement. Click the button on the system that saves still images to save this image as a still image containing the measurement. Continue scanning in a transverse plane to visualize the entirety of the aorta through the bifurcation and capture the images.When a live image of the distal aorta is optimized, measure the AP diameter of the infrarenal aorta. Press caliper or measure and move the track ball or touch pad of the system to the outer edge of the anterior wall, the adventitia and click select. Move the track ball or touch pad again to the outer edge of the posterior wall and click select.Wait for the system to generate a measurement. Save the still image as demonstrated previously. Adjust the depth as the abdominal aorta courses coddly through the abdomen becoming more superficial and tapering slightly.Continue scanning coddly through the aortic bifurcation into the left and right iliac arteries. Adjusting the depth to maintain the aorta in vertebral body in the middle of the screen. Capture images while scanning through the bifurcation.When imaging the abdominal aorta in the transverse plane, an aorta measuring greater than 3 centimeters was considered aneurysmal. Such aneurysms also showed the presence of a hematoma filling most of the lumen. The presence of an intimal flap within the lumen of the aorta indicated aortic dissection.Depending on the chronicity of the dissection, the flap was either thin and moved with the pulsations of the aorta or thickened and had an adjacent hematoma. An acute thoracic aortic dissection was found to extend through the abdominal aorta and into the right iliac artery.

Advancing Bedside Care: A Multidisciplinary Guide to Kidney-Genitourinary POCUS

Point-of-Care Kidney and Genitourinary Ultrasound in Adults: Image Acquisition

A range of conditions involving the kidneys and urinary bladder can cause organ-threatening complications that are preventable if diagnosed promptly with diagnostic imaging. Common imaging modalities include either computed tomography or diagnostic ultrasound. Traditionally, ultrasound of the kidney-genitourinary system has required consultative teams consisting of a sonographer performing image acquisition and a radiologist performing image interpretation. However, diagnostic point-of-care ultrasound (POCUS) has recently emerged as a useful tool to troubleshoot acute kidney injury at the bedside. Studies have shown that non-radiologists can be trained to perform diagnostic POCUS of the kidneys and bladder with high accuracy for a set number of important conditions. Currently, diagnostic POCUS of the kidney-genitourinary system remains underused in actual clinical practice. This is likely because image acquisition for this organ system is unfamiliar to most clinicians in specialties that encounter acute kidney injury, including primary care, emergency medicine, intensive care, anesthesiology, nephrology, and urology. To address this multi-specialty educational gap, this narrative review was developed by a multi-disciplinary group to provide a specialty-agnostic framework for kidney-genitourinary POCUS image acquisition: indications/contraindications, patient positioning, transducer selection, acquisition sequence, and exam limitations. Finally, we describe foundational concepts in kidney-genitourinary ultrasound image interpretation, including key abnormal findings that every bedside clinician performing this modality should know.

Author Spotlight: Developing a Bedside Protocol for Kidney and Genitourinary Ultrasonography

Point-of-care ultrasound (POCUS) of the renal and genitourinary (renal-GU) system can help to screen for certain causes of kidney dysfunction. However, despite its clinical utility, renal-GU POCUS remains underutilized due to a lack of training among clinicians. To address this gap, this article describes renal-GU image acquisition and interpretation.

A range of conditions involving the kidneys and urinary bladder can cause organ-threatening complications that are preventable if diagnosed promptly with ...

Training Novices in POCUS for Vascular Cannulation Using Simulation Models

Using Simulation Models to Train Clinicians in the Use of Point-of-Care Ultrasound 

The use of point-of-care ultrasound (POCUS) has shown to be a beneficial non-invasive vascular access assessment method by clinicians, which can provide critical elements of visual and measurable information that proves to be useful in the context of vascular access cannulation, in combination with the practical skill of the clinician performing the cannulation. However, the use of POCUS in this context is to practically train and enable individuals who are novices in using this technique to become proficient in performing this task subsequently on patients in a careful and successful way. The simulation of these vascular conditions may be useful to help healthcare professionals learn, understand, apply, and establish such practical skills for vascular cannulation safely to achieve the desired outcomes. This project intended, through the attendance of a half-day workshop, to establish skills to use POCUS in connection with simulation models and perform specific tasks to enable clinicians to use this method in their clinical practice for vascular access cannulation in patients. A mixed-methods longitudinal study design was used to evaluate the effect of a point-of-care ultrasound workshop for peripheral intravenous cannula insertion, including specific tasks for the participants to be performed on simulation models. A total of 81 individuals participated in 11 half-day workshops through 2021 and 2022. Offering a workshop that uses simulation models in combination with various POCUS devices is useful in establishing this newly learned skill in clinicians, such as measurements of depth, caliper, and direction of a vein with POCUS prior to cannulation providing essential anatomical facts to the operator, which increases the likelihood of first-time success in cannulation.

Author Spotlight: Evaluating Clinicians&#039; Adoption of Ultrasound-Guided Vascular Cannulation Through Simulation Training

The present protocol describes an ideal solution to train novices in the use of point-of-care ultrasound devices for the practical clinical skill of visually assessing distinct individual anatomical vascular conditions prior to and during an intended venous vascular cannulation using point-of-care ultrasound in a patient.

The use of point-of-care ultrasound (POCUS) has shown to be a beneficial non-invasive vascular access assessment method by clinicians, which can provide ...