FIGURE 131.10 Probe position for the parasternal long cardiac view FIGURE 131.11 Normal parasternal long cardiac view: Right ventricle (RV), left ventricle (LV), mitral valve (MV), aortic root (Ao), pericardium (P) Fluid will accumulate just above the pericardium in a pericardial effusion The apical four-chamber view can be the most difficult cardiac view to obtain This window is obtained at the apex of the heart by placing the probe over the patient’s point of maximal impulse, typically around the fifth intercostal space, and aiming toward the patient’s right shoulder (probe marker pointing to the patient’s right) In this view, all four chambers of the heart can be seen and it can provide information about the relative dimensions of the right and left ventricles Pitfalls There are several reasons why a sonographer may not see the heart during the cardiac examination In the subxiphoid view, the heart often lies deeper than the depth set on the screen To avoid this, the depth should be set to its maximum level and once the heart is located, the depth should be changed accordingly to optimize and center the image In addition, the angle of the probe in the subxiphoid view may be too steep Remember that from the subxiphoid position, the heart lies superiorly, and thus the head of the transducer must be pointed in that direction, toward the left shoulder In the subxiphoid view, air from the stomach can scatter the ultrasound beams, rendering the image useless Slide the probe to the patient’s right, away from the stomach, thereby using the liver as an acoustic window instead In the parasternal views, rib shadows are often encountered The probe may be shifted to the patient’s left, be rotated, or be angled obliquely to better fit the transducer footprint in between adjacent ribs The apical four-chamber view can be a challenging view to obtain Having the patient sit forward or lying in the left lateral decubitus position can bring the heart forward and closer to the probe allowing better visualization Chest Thoracic ultrasound can be used for the rapid identification of pulmonary pathology, including pneumothorax and pleural effusion Ultrasound has long been the reference standard for the identification of pleural effusions and can also be used to guide procedures such as thoracentesis POCUS may be more sensitive for the diagnosis of pneumothorax than a single supine chest x-ray Anatomy The principles of lung ultrasound are different than those for ultrasound imaging of other organs due to the fact that air scatters ultrasound waves, making direct visualization of lung tissue difficult Lung ultrasound thus relies mainly on the interpretation of image artifacts in order to identify pathology In the normal lung, the visceral and parietal pleura merge to form a single pleural line that appears as a hyperechoic (bright) line below the muscle of the chest wall and immediately deep to the ribs Normal lung sliding occurs as the visceral pleura glides back and forth over the parietal pleura ( Video 131.11 ) On dynamic ultrasound imaging this appears as a slight movement or “sparkling” pattern of the hyperechoic pleural line that varies with the respiratory cycle On M-mode, normal lung sliding generates what is referred to as the “seashore sign” where the top of the image (representing the nonmoving chest wall) appears as horizontal lines, or the “waves,” and the bottom of the image (representing the aerated, expanded lung) appears as the “grains of sand” (Fig 131.12 A ) Technique Pediatric lung ultrasound is generally performed using a linear, high-frequency probe because this provides adequate depth and higher-quality image resolution than a convex, low-frequency probe Patient positioning will depend on the clinical scenario—patients who are critically ill can be examined in the supine position, while those who are more stable can be placed in the seated position In addition, certain findings will be more easily seen with different patient positioning For example, pneumothorax will be more easily detected in the anterior lung fields of a supine patient, while pleural effusions will be better visualized in the lower lung fields of a seated patient Starting in the longitudinal view with the probe marker pointing toward the patient’s head, the lung can be scanned sequentially in all areas of the thorax or, alternatively, a more targeted assessment can be performed Pneumothorax will appear as the absence of lung sliding ( Videos 131.11 [normal] and 131.12 [pneumothorax]) On M-mode, this will appear as the “stratosphere” or “barcode” sign, with the entire image showing no movement and thus appearing as horizontal lines all the way down (Fig 131.12 B ) Pleural effusions, which can generally first be seen in the posterior costophrenic sulcus, appear as an anechoic fluid layer overlying the pulmonary parenchyma Transudate and hemothorax may appear as simple, anechoic fluid ( Video 131.13 ) while an empyema can have internal septations or organized fibers ( Video 131.14 ) FIGURE 131.12 A: Normal motion-mode of lung Commonly referred to as “seashore” sign with “waves” and “sand.” B: Pneumothorax, known as the “barcode” sign Pitfalls Lung sliding from the opposing pleura can be a subtle finding and has the potential for misinterpretation by the novice sonographer Additionally, cardiac movement, especially when scanning on the left side of the chest, can sometimes be confused for lung sliding Newer ultrasound machines may have significant postprocessing in order to minimize artifacts and create clearer images This postprocessing can interfere with traditionally described thoracic imaging artifacts and make interpretation more difficult ... (representing the aerated, expanded lung) appears as the “grains of sand” (Fig 131.12 A ) Technique Pediatric lung ultrasound is generally performed using a linear, high-frequency probe because this