Functional Hemodynamic Assessment in Shocked Patients in the Pediatric Intensive Care Unit

Shock is a leading cause of morbidity and mortality in pediatric patients worldwide (1, 2). The prevalence of sepsis and septic shock has been reported to be around 1-26% of shock cases with mortality rates ranging from 5 to 35% in hospitalized children globally (3, 4).

Appropriate fluid resuscitation is crucial in the management of children with shock (5). The current American College of Critical Care Medicine (ACCM), Pediatric Advanced Life Support (PALS), and Surviving Sepsis Campaign Guidelines have focused on the implementation of early and goal-directed fluid therapy (6, 7). Many studies have shown that mortality in pediatric patients with septic shock has been significantly decreased with aggressive fluid administration (8, 9). However, overzealous fluid administration can also lead to fluid overload (FO) and has been associated with complications such as acute respiratory distress syndrome (ARDS), which results in poor outcomes including increased hospital length of stay and mechanical ventilator days (10-13). As a result, in the recent decades, a more restrictive approach for fluid resuscitation has emerged in adults and children vs. the usual aggressive fluid therapy (14-16).

Traditional use of subjective findings such as pulse volume, capillary refill time, and clinical signs of hydration status to predict fluid responsiveness (FR) has been proven to be unreliable (17, 18).

While there is a growing body of the literature on the use of non-invasive devices for objective hemodynamic monitoring, there is a paucity of the literature related to the assessment of FR using these measures in children with shock (19).

Noninvasive monitoring techniques for the assessment of various cardiovascular parameters are increasingly accepted as the current medical practice. Electrical cardiometry (EC) is one such method for the determination of stroke volume (SV), cardiac output (CO), and other hemodynamic parameters and is based on changes in electrical conductivity within the thorax (20).

ICON® based on Electrical Cardiometry™ (EC) technology (Osypka Medical GmbH, Berlin, Germany) is a noninvasive, continuous hemodynamic monitoring device. It determines the CO by measuring variations in the thoracic electrical bioimpedance with phases of a cardiac cycle. During diastole, the erythrocytes in the aorta assume a random orientation (more impedance), while during systole the pulsatile blood flow causes them to align parallel to both the blood flow and the electrical current (less impedance). The magnitude of the maximum rate of change of impedance with a change in the orientation of erythrocytes gives a peak aortic blood flow acceleration and stroke volume (21).

Cardiac index (CI), systemic vascular resistance index (SVRI), cardiac contractility, stroke volume variation (SVV) and thoracic fluid content (TFC) are derived using complex mathematical formulae and patented algorithms. The accuracy and the clinical utility of electrocardiometry have been validated against other measures of CO like direct Fick' s method, thermodilution, and transthoracic and transesophageal echocardiography in a wide spectrum of patient conditions and populations across all ages, including critically ill patients, intraoperative settings, cardiac catheterization, and congenital heart diseases (22-26).