The pediatric intensive care unit (PICU), like other intensive care units (ICU), is a dynamic place that provides multidisciplinary care with the integration of numerous medical and surgical subspecialists who come together with a common goal—the care of a critically ill child. Predictably, the diseases span the spectrum of adult ICU care and range from acute illnesses such as septic shock and sepsis-related cardiomyopathy to hemorrhagic shock with traumatic visceral rupture. While the problems are similar to those encountered in adult ICUs, three additional layers of complexity are important to understand when caring for a critically ill child, namely age, size, and developmental status; all of these have relevance for critical care ultrasonography. First, many differential diagnoses encountered in the PICU are age dependent, which is important for the ultrasonographer to remember when performing ultrasound for diagnostic purposes on a child. Second, a child’s size may range from <2 to >200 kg, which has important implications for the technical aspects of ultrasound procedures. Finally, children may not be able to cooperate with an examination or procedure like adults can, making the use of ultrasonography, a pain-free and noninvasive tool, an ideal method for extending one’s physical examination. Bedside ultrasound is an important and evolving tool for pediatric intensivists and can be used to evaluate many disease processes, assist in procedural interventions, and assess for complications related to those procedures. While ultrasound technology has long been available, recent advancements have improved image quality and capabilities and have reduced equipment bulk, making point-of-care use in critical care areas considerably more feasible.¹ This chapter aims to provide a practical discussion on the use of bedside ultrasonography in the PICU.

Ultrasound use in the PICU ranges from being an aid for vascular access to being a versatile instrument that is able to perform an acute, comprehensive assessment of the critically ill child at the bedside and monitor response to critical treatment. Common indications for bedside ultrasound in the PICU are listed in Table 5-1.

Similarly, equipment also ranges from simple ultrasound with the use of a linear probe for vascular access to an instrument with multiple probes that can be manipulated and enhanced to provide the best visualization of cardiac, abdominal, vascular, and thoracic structures (see Chapter 3). Pediatric-sized probes are also available. Small hockey stick style linear probes have a small footprint and are able to provide excellent images in less accessible areas of the body such as the neck or axillae; small-phased array probes are also available for focused echocardiography but are infrequently necessary.

In some PICUs, a portable notebook-type ultrasound system is placed on a mobile cart with a curvilinear abdominal probe, a linear high frequency probe, and a low-frequency cardiac probe. These probes can be manipulated in terms of frequency, depth of ultrasound beam, and use of Doppler technology, but many systems have a very short power-on-to-scan-time and require very little manipulation to provide good images. They are lightweight, easily maneuvered, and have a very small footprint. These systems receive regular use in vascular access, thoracic and abdominal ultrasonography and focused echocardiography.

The use of procedural ultrasound in vascular access, namely central venous catheter placement, is more efficient and safer than techniques using palpation and landmarks.² Studies have demonstrated that the routine use of internal jugular central venous line (CVL) placement in children under ultrasound guidance improves speed and results in fewer attempts and fewer complications. Specifically, a study by Verghese et al.³ investigating the use of ultrasound imaging to place internal jugular CVLs in infants prior to cardiac surgery found that imaging reduces the number of cannulation attempts, time to catherization, and number of carotid artery punctures, and improves the success rate for catheter placement. Similarly, a study by Alderson et al.,⁴ which compared ultrasound-guided internal jugular cannulation with landmark techniques in infants, revealed that ultrasound assistance improves success rates and reduces time to cannulation. In addition, Maecken et al.⁵ demonstrated that the inconsistent location and relationship between the internal jugular vein and carotid artery makes ultrasound guidance a useful tool.

Ultrasound guidance is beneficial in several ways. First, a survey of the vessels prior to deciding upon an access site is useful in children with vascular and anatomic abnormalities or those who have disease processes that predispose them to venous clotting or have undergone multiple cardiac catheterization procedures through access of the femoral vessels. Second, ultrasound helps confirm the position and relative position of the vein and its relationship to the artery and other anatomic structures (Figures 5-1, 5-2, and Video 5-1). Third, placement of the catheter using the landmark method or by palpating the artery can be imprecise, so ultrasound guidance may be used to improve specificity. Fourth, children, who tend to have smaller structures and more subcutaneous fat, frequently do not have reliable landmarks. Fifth, ultrasound can be used to confirm proper placement of the catheter (Figure 5-3). Finally, after difficult or repeated attempts to obtain vascular access, ultrasound can confirm whether a perivascular hematoma may be impeding vessel cannulation (refer Chapter 27 for a step-by-step guide to the use of ultrasound in venous cannulation).

Video 5-2 shows a longitudinal image of an internal jugular vein with a guide wire in the lumen. Ultrasound-guided confirmation of vessel cannulation has been made prior to dilation of the vessel.

Focused or bedside echocardiography, combined with physical examination, has proven to improve clinical diagnosis and management of acutely ill patients. Point-of-care echocardiographic examination is typically geared towards answering a specific clinical question regarding the current state of hemodynamics and is generally shorter in duration than a traditional examination.⁶ Data indicate that portable echocardiography performed by noncardiologists is largely accurate in diagnosing cardiac issues such as pericardial effusion (91%), left ventricular (LV) size (96%), and LV systolic function (96%).⁷ Specifically, pericardial effusions appear as anechoic areas within the pericardial space (Figure 5-4), with right atrium and ventricle compression present in tamponade. Reduced LV function may be identified via observation of limited cardiac wall movement between diastole and systole.⁸

In the pediatric cardiac ICU, focused echocardiography aids in the diagnosis and management of pericardial effusion/tamponade, depressed cardiac function, hemodynamically significant pleural effusions, and aids in volume status assessment. It can also be performed quickly during the pulse check of advanced cardiac life support, to diagnose potential causes of cardiac arrest.⁸ In addition, using more advanced techniques, right-sided heart failure can be rapidly evaluated with an assessment of right ventricular (RV) volume, tricuspid regurgitation, and paradoxical septal wall motion. These findings may be used to augment data from other hemodynamic measurements to confirm RV failure due to right ventriculotomy or pulmonary hypertension. Similar findings are seen in adult patients and older pediatric patients who have hemodynamically significant pulmonary embolism.

Transthoracic echocardiogram is the most widely used primary imaging technique for characterizing simple and complex structural cardiac defects,^9,10 and may be employed in a focused manner in the ICU. Importantly, it is noninvasive, universally available, and can provide detailed and quantifiable information on intracardiac morphology and function, valve gradients, pulmonary artery pressure, and chamber hypertrophy and enlargement at the bedside of the critically ill patient.^9,11 While transesophageal echocardiography may need to be used as an alternative in patients with poorer transthoracic windows, this is usually not an issue among pediatric patients.⁹

The need to assess cardiac function may be underestimated in the general PICU.¹² The use of focused echocardiography may be useful in guiding patient management in undifferentiated, fluid-resistant hypotension. It allows the rapid assessment of global cardiac function, LV chamber dimensions, volume status, and identifies hemodynamically significant pericardial effusions (Table 5-2), all of which may influence management. Spurney et al.⁷ demonstrated that with limited training and limited echocardiographic views (Figures 5-5 and 5-6), PICU physicians are capable of diagnosing significant pericardial effusions, decreased LV systolic function, and LV enlargement. Milner et al.¹³ showed that children with altered mental status and tachycardia may be diagnosed with pericardial effusion and tamponade by cardiologist-performed bedside echocardiography, resulting in earlier diagnosis and improved outcomes. Focused bedside echocardiography also enables clinicians to perform serial bedside examinations and allows for important assessment and reassessment of the adequacy and efficacy of therapy (Videos 5-3 and 5-4).