Troubleshooting FoCUS Image Acquisition: Patient Positioning, Transducer Manipulation, and Image Optimization

Focused cardiac ultrasound allows clinicians to perform problem-oriented ultrasound exams at the bedside to answer real-time clinical questions. The process is rapid, pragmatic, and repeatable in the clinical setting. The implications of this exam are applicable across the spectrum of critical illness because it provides information to aid in the clinical assessment of cardiac function, fluid status, and other hemodynamic features.

Demonstrating this procedure will be doctors Adam Gottula and Suhas Devangam, fellow physicians, and Dr.Jessica Koehler, faculty physician at my institution. Begin by placing the patient in the supine position. If there is difficulty obtaining the parasternal long axis image, place the patient on their left side and extend their arm above their head.

Place the transducer at an oblique angle between the third and fifth intercostal space of the parasternal region, with the transducer marker pointing to the patient's right shoulder. Visualize the right ventricle, left ventricle, left atrium, mitral valve, left ventricular outflow tract, aortic valve, and descending thoracic aorta. Then visualize the simultaneous opening and closing of the mitral and aortic valves to ensure the image is not foreshortened.

Now start with an initial depth of approximately 15 to 20 centimeters, and adjust the depth so that the tip of the mitral valve is in the center of the image and the descending thoracic aorta is visible. Adjust the gain to maximize the visibility of the myocardium and mitral valve, and move the focus of the region of interest most focused at a depth of the mitral valve. To obtain this image, place the patient as previously demonstrated or in the supine position.

Place the transducer approximately 90 degrees relative to the transducer in the parasternal long axis. Then tilt the transducer until the mid papillary muscles are visualized for the focus assessment. Tilt the transducer toward the base of the heart.

Start with a deeper image to identify any pleural effusion. Adjust the depth to include the full depth of the left ventricle and diffuse centimeters beyond to ensure that a pericardial effusion would be fully visualized. Adjust the gain to maximize visualization of the septum and papillary muscles.

Afterward, adjust the focus to the papillary muscles. Position the patient on their left side with their left arm extended above their head. If a significant artifact is present, have the patient exhale and hold their breath to minimize pulmonary artifact.

Position the transducer in the fourth through sixth intercostal space along the left anterior auxiliary line, with the transducer marker pointed to the left axilla. Move the transducer lateral, medial or coddle to obtain an optimal apical four chamber view. If necessary, lift the breast tissue to allow probe access.

If the left ventricular apex is not fully visualized, move the transducer lateral while orienting the transducer toward the right shoulder. In the normal heart, the apex of the left ventricle is at the top and center of the sector, the right ventricle is triangular and smaller, and the myocardium should be uniform from the apex to the atrio ventricular valves. Now capture an apical four chamber view that includes both atria ventricles, the inter ventricular septum, and the lateral portions of the tricuspid and mitral annuli.

The aortic valve and left ventricular outflow tract should only be present in an apical five chamber view. To improve the image of the valves, slide the transducer up or down a rib space, and tilt the base of the transducer down. If the base of the transducer is tilted too far down, an apical five chamber view, including the aortic valve, will appear, and the transducer should be tilted back up to optimize the apical four chamber view.

Rotate the base of the transducer toward the patient's midline to optimize the inter ventricular septum position, which should be present vertically in the center of the image. Image both the atria and increase the depth to include both atria at the image's deepest point and accommodate the left and right ventricular free walls. Adjust the gain to maximize visibility, often resulting in increased echogenicity of the myocardium, the mitral valvular annulus, and the tricuspid valvular annulus.

Adjust the focus to the depth of the valvular annuli. The focused cardiac ultrasound parasternal long axis, parasternal short axis, apical four chamber, subcostal four chamber, and inferior vena cava images are being shown. The stereotactic and psychomotor aspects of the focused cardiac ultrasound require repetition, time, and experience to achieve mastery.

The experience should include the performance of exams on patients with varying body habitus in a diversity of clinical settings. There are some clinical scenarios in which limitations cannot be overcome. A skilled provider will recognize situations in which focused cardiac ultrasound should not be performed and pursue alternative investigations such as transesophageal or comprehensive transthoracic echocardiography.