The Application of Point-of-Care Ultrasonography (POCUS) in the Management of Acute Respiratory Distress Syndrome (ARDS) in the Intensive Care Unit

We have organized standardized procedures for performing POCUS on ARDS patients in the intensive care unit. Bedside ultrasound technology has developed rapidly in multiple fields, yet there is a lack of standardized research specifically targeting patients with ARDS. To begin, perform a longitudinal scan in the intercostal space and locate the pleural line approximately 0.5 centimeters below the rib line, visible as a hyperechoic horizontal line.

Identify A-lines as horizontal hyperechoic artifacts of the pleural line indicative of a high gas volume ratio beneath the pleura. Using M mode, check for the presence of the seashore sign, indicating normal lung sliding, or the stratosphere sign, indicating absent lung sliding, suggestive of pneumothorax. Then, identify B-lines as vertical hypoechoic artifacts originating from the pleural line that extend to the bottom of the screen and erase the A-lines.

Now, check for the shred sign, represented by subpleural hypoechoic areas with irregular boundaries, indicating small consolidations. Look for a tissue-like pattern in areas of large consolidation, characterized by liver-like echogenicity. Use a right ventricular focused apical four-chamber view.

At end diastole, trace the right ventricular endocardial border to measure the end diastolic area. Measure the right ventricular free wall thickness at end diastole. Now, use the M mode to measure tricuspid annular plane systolic excursion.

Measure the inferior vena cava diameter and collapsibility during a sniff. Next, identify the diaphragm as a three-layered structure with a hypoechoic muscle layer between hypoechoic pleural and peritoneal lines. Record B mode clips or still images during end inspiration and end expiration.

Then, measure the diaphragm thickness from the middle of the pleural line to the middle of the peritoneal line. Now, place the probe sagittal below the right costal margin between the midclavicular and anterior axillary lines to scan the right diaphragm, then, place the probe sagittal below the left costal margin between the anterior and midaxillary lines to scan the left diaphragm. For femoral vein assessment, place the patient in a supine position with hips externally rotated into the frog leg position to optimize exposure.

For popliteal vein evaluation, maintain the knee in slight flexion between 15 and 30 degrees to avoid venous compression. In obese patients, use lateral decubitus or prone positioning to improve acoustic access and tissue displacement when standard views are inadequate. Start scanning the femoral zone at the inguinal crease to identify the common femoral vein.

Move the probe distally to visualize the junction of the femoral vein and the deep femoral vein. Compress the vein every centimeter along its course to assess venous compressibility. Scan the popliteal zone from the popliteal vein to the confluence of the anterior tibial, posterior tibial, and peroneal veins.

Compress the vein every one centimeter to confirm full compressibility. Identify the liver as the cephalad structure located on the left side of the screen. Locate the aorta or inferior vena cava and adjust the imaging depth to visualize their posterior boundaries or the vertebral body.

Sweep the probe laterally from left to right while keeping it perpendicular to the skin. Identify the stomach, liver, pancreas, superior mesenteric artery, aorta, and inferior vena cava. Use the supine position to assess gastric fullness, noting that it cannot exclude the presence of contents.

Place the patient in the right lateral decubitus position to allow gravitational flow of gastric contents into the antrum for more accurate volume measurement. Measure the cross-sectional area of the gastric antrum at the level of the aorta to avoid underestimation of volume. Ensure the aorta is correctly identified during measurement.

Representative ultrasound images showed normal pulmonary findings, including visible pleural lines, A-lines, and the seashore sign. The presence of fewer than three B-lines per intercostal space was observed, but the concurrent appearance of a shred sign indicated focal pulmonary consolidation. A stratosphere sign was observed, characterized by static horizontal lines and absence of the seashore sign, indicating pneumothorax.

Ultrasound imaging showed pleural effusion with accompanying pulmonary consolidation, as evidenced by air bronchogram signs. Varying degrees of pleural effusion accumulation were observed in two cases. Echocardiography revealed clear visualization of cardiac chambers, including both atria and ventricles.

Diaphragm motion patterns were evaluated. Ultrasound assessment of the lower extremity veins showed compressibility testing at the common femoral vein and the popliteal vein. Ultrasound of the stomach showed an empty stomach with a bullseye appearance and minimal clear basal secretions.

Repositioning the patient in right lateral decubitus allowed the gastric contents to gravitate toward the antrum. We have established that our comprehensive POCUS protocol enables time multi-system assessment to guide personalized management of ARDS in the ICU. Our protocol addresses the gap in standardized multi-organ POCUS guidelines for dynamic monitoring and intervention in ARDS beyond isolated lung ultrasound scoring.

Future research will focus on standardizing training, validating POCUS-driven therapeutic algorithms, and exploring its utility in resource-limited settings.