Therapeutic Applications for Bedside Ultrasonography

Bedside ultrasonography is a modality that is rapidly increasing in popularity due to its ease of use, increased availability, near immediate time to diagnosis, and reimbursement potential. Clinicians may not be aware of the wide diversity of therapeutic applications for ultrasound that can safely and easily be employed. Clinicians may dramatically increase their ultrasound armamentarium by ensuring they are avoiding common pitfalls and utilizing all the benefits that their ultrasound equipment has to offer. The image shown demonstrates the spinous process (arrow) from an ultrasound-guided lumbar puncture.

Ultrasound is also well supported in the literature for identification of foreign bodies and procedural guidance for their removal. Ultrasound may be able to detect radiolucent foreign bodies that do not appear on x-rays. In some cases, a sinus tract with air may be detected and help localize the foreign body. In the image shown note the hyperechoic line with a small reverberation artifact, typical of foreign bodies (yellow arrow). The hyperechoic lines on the left of the screen (blue arrow) are from a large-bore needle being inserted for attempted removal. Under direct visualization the occult foreign body can be readily manipulated and retrieved.^[1,2]

Ultrasound can help provide regional anesthesia for fracture reductions. Fractures can be readily identified by a step-off in the bone cortex; ultrasound is especially helpful in identifying radiographically occult fractures such as in patients with osteopenia. A fracture or hematoma block can then be performed by angling the needle pathway (dashed orange lines) such that the tip lines up with the fracture (arrow). Anesthetic can then be injected without the need for intravenous access. This is especially helpful in patients who are elderly, intoxicated, or with brain injury for whom sedating and hypotensive effects of systemic narcotics can be dangerous.^[3-5]

Ultrasound-guided femoral nerve blocks are being employed as a means of analgesia in elderly patients with hip fractures. By reducing or eliminating the need for narcotics, ultrasound-guided femoral nerve blocks are viewed as a safe way of controlling pain in this high-risk population. A noncutting spinal needle should be utilized. Care must be taken to appropriately identify the needle track (dashed orange lines) pathway to the femoral nerve (yellow circle) in order to avoid the superior (SFA) and deep femoral arteries (DFA). After injection, pressure should be applied with the patient in the Trendelenburg position to facilitate anesthetic spread.^[6]

Ultrasound-guided nerve blocks of the forearm (radial, median, and ulnar) provide excellent anesthesia in hand and wrist procedures. The procedure is typically performed in the proximal forearm. Nerves can be identified by their honeycomb appearance and anisotropy (i.e., brightness changes as the operator changes the beam angle).

Identification and evaluation of joint effusions are common tasks for the emergency and acute care physician. Ultrasound-guided arthrocentesis can assist in this process, particularly in joints in which the physician is less familiar with anatomic landmarks such as the elbow, ankle, or hip. Pictured is a small hip effusion (Ef) with the femur (Fe) and acetabulum (Ac) as important landmarks. Reactive effusions will have an anechoic appearance while septic effusions are more likely to have internal echoes. Lipohemarthrosis may appear as multiple fluid levels.

A large knee effusion (Ef) is shown, likely chronic in nature. Notice the thickened synovium (Sn) with an appearance similar to bowel in ascites. A needle for arthrocentesis (arrow) is being placed to the right of the synovium (hyperechoic area with small reverberation artifact). Ultrasound is usually unable to determine the etiology of the synovial proliferation.

Shoulder dislocations can be readily identified with treatment facilitated by ultrasonography. A curvilinear transducer is placed over the posterior lateral aspect of the affected shoulder, inferior to the scapular spine. A vacated glenohumeral joint space (yellow arrow) can be readily identified between the dislocated humeral head (H) and glenoid (G). Under guidance, a needle can be inserted to drain hemarthrosis and inject anesthetic. Once the local anesthetic has taken effect, the shoulder can be more easily reduced without the need for intravenous access. Relocation can then be confirmed with ultrasound.^[7,8]

Ultrasound-guided lumbar punctures are especially helpful in patients who are obese or have spinal disorders because the surface landmarks may be obscured. Placing the probe in the transverse plane allows identification of the midline of the spine, which is marked. The probe is then placed in the sagittal orientation to identify the interspinous space (line) between the 2 spinous processes, which is marked. The spinal needle can then be placed at the intersection of the 2 lines and the lumbar puncture can proceed as normal.

Free fluid within the abdomen may be reliably detected by ultrasound with as little as 100 mL of fluid present. While traditionally paracentesis was performed blindly in the left lower quadrant, ultrasound guidance allows localization of fluid in a variety of dependent areas. The light blue arrow demonstrates the needle tip entering the ascitic area, safely away from the underlying bowel. It is important to pan through the potential site of access to ensure floating loops of bowel are safely distant. In general, 5-7 cm of clear space is needed to accommodate bowel motion.

Pericardial tamponade is a life-threatening disease that can be readily diagnosed and treated with the assistance of ultrasound. Pericardial fluid is readily identified as a hypoechoic collection (yellow arrow) surrounding the heart (RV = right ventricle, LV = left ventricle). At the same time, hemodynamics can be examined by looking for abnormal septal motion, right-sided inversion, and decreased respiratory variation of the diameter of the inferior vena cava. Ultrasound visualization ensures the needle tip is pericardial and not intracardiac and allows confident evacuation and, if indicated, drain placement.

Multiple specialties in medicine have described the utility of ultrasound-guided placement of central lines. In comparison with the traditional landmark approach, ultrasound-guided central line placement results in fewer complications, less time to successful cannulation, and fewer needle sticks. The image shown is a transverse ultrasound view of an internal jugular cannulation with the arrow pointing to the needle with associated reverberation artifact as it cannulates the vessel. Special echogenic polymer-coated needles can be used, which will make the needle more visible during cannulation.^[9,10]

An alternative approach to ultrasound-guided central line placement is a long axis orientation. After first identifying the vessel in a transverse orientation, the sonographer rotates the probe 90° to obtain a long axis view. This method allows visualization of the needle in the plane of the ultrasound beam, potentially reducing cannulation through the posterior wall of the vessel. The blue arrows show the wire as it is being threaded into the vessel. The needle or wire will be most visible when perpendicular to the ultrasound beam, which can be achieved by either rocking the ultrasound probe or using beam steering technique.

Peripheral intravenous (IV) placement under ultrasound guidance is a difficult procedure to master, but its use can avoid central lines, decrease the time to successful IV placement, and reduce the number of punctures. The ideal vein will be shallow, large, and have a straight course. Long catheters (20 gauge, 1.88") are often needed. The blue dashed lines indicate the path of the needle as it approaches one of the paired brachial veins (V1), while the red arrow shows the typical "target sign" as the needle tip enters the vessel. The other brachial vein (V2) and brachial artery (A) are identified.^[11,12]

A long axis approach to peripheral IV placement with dashed lines representing the needle path is shown. The most common complications are arterial puncture or paresthesia. The vein should be readily differentiated from the artery because it should be compressible with a venous waveform on color flow or spectral Doppler. Cannulating the shallower cephalic or basilic veins reduces the risk for arterial puncture. Paresthesias are usually secondary to injury to the median or median cutaneous nerves.

Related Slideshows

• Best Practices: Arthrocentesis
• Best Practices: Regional Blocks
• Bedside Ultrasonography, Gallbladder Evaluation
• Life-Threatening Pericardial/ Myocardial Pathology
• Other Slideshows

For more information, see the following resources:

• Medscape Reference: Abdominal Bedside Ultrasonography
• Medscape Reference: Bedside Ultrasonography for Lumbar Puncture
• Medscape Reference: Bedside Ultrasonography for Pneumothorax
• Medscape Reference: Pericardiocentesis

Contributor Information

Authors
Richard A. Taylor, MD
Ultrasound Fellow, Clinical Instructor
Department of Emergency Medicine
Yale University School of Medicine
New Haven, Connecticut

Disclosure: Richard A. Taylor, MD, has disclosed no relevant financial relationships.

Christopher Moore, MD
Associate Professor of Emergency Medicine
Director, Division of Emergency Ultrasound
Emergency Ultrasound Fellowship Director
Yale University School of Medicine
New Haven, Connecticut

Disclosure: Christopher Moore, MD, has disclosed no relevant financial relationships.

Contributor Information

Editor
Lars Grimm, MD, MHS
House Staff
Department of Diagnostic Radiology
Duke University Medical Center
Durham, North Carolina

Disclosure: Lars Grimm, MD, MHS, has disclosed no relevant financial relationships.

Reviewer
Timothy Jang, MD
Assistant Professor of Medicine
David Geffen School of Medicine
University of California, Los Angeles
Director of Emergency Ultrasound
Olive View-UCLA Medical Center
Clinical Faculty, Washington University School of Medicine
Torrance, California

Disclosure: Timothy Jang, MD, has disclosed no relevant financial relationships.