A trend skill that makes pediatric intensivists stand out: Critical care echocardiography

Abstract

Recently, the use of point‐of‐care ultrasonography (POCUS) by pediatricians especially in emergency and intensive care departments has become increasingly popular. Critical care echocardiography (CCE) quickly and accurately identifies cardiac function, allowing intensivists to manage critically ill pediatric patients by manipulating vasoactive–inotrope–fluid treatment based on the echocardiographic results. Training courses for POCUS are increasingly available and more intensivists are learning how to use CCE. In this review, we focus on the importance and utility of CCE in pediatric intensive units and how it assists in the management of hemodynamically unstable pediatric patients. We highlight the common measurements carried out by intensive care specialists and emphasize the role of the CCE methods in PICUs.

Introduction

Most pediatric intensive care units (PICUs) have adopted point‐of‐care ultrasonography (POCUS) technology.¹, ² Many pediatric intensive care organizations offer advanced instructional classes and promote POCUS use by the pediatric intensive care specialists. The European Society of Pediatric and Neonatal Intensive Care (ESPNIC) global evidence‐based guide regarding POCUS for severely ill neonates and children supports POCUS use in PICUs.³ Critical care echocardiography (CCE), a significant application of POCUS, is used in the routine assessment of patients in most PICUs.⁴, ⁵ It was used 79.3% in a survey conducted at the PICUs in Turkey.⁶ CCE is a key tool for hemodynamic evaluation in intensive care units as it provides timely assessment of haemodynamic changes in severely ill pediatric patients and assists with determining the appropriate clinical treatment.⁷, ⁸ POCUS is utilized to evaluate ventricular systolic function, cardiac output, volume status and response to fluid management; detection and management of pericardial effusion/cardiac tamponade and cardiac arrest in pediatrics.⁹, ¹⁰

Assessment of ventricular systolic function

Left ventricular (LV) systolic function is used for haemodynamic monitoring of severely ill patients. Ranjit et al.¹¹ demonstrated the role of echocardiographic assessment of LV systolic function in haemodynamic assessment in addition to physical examination and invasive blood pressure monitoring of pediatric patients with septic shock. Assessment of LV systolic function may be qualitative or quantitative. Myocardial thickening is visually assessed in the qualitative examination of the LV systolic function.¹² Quantitative assessment includes LV ejection fraction (EF) can be measured from different echocardiography views: the parasternal long axis view, the apical four chamber and subcostal views. The change in the ventricular chamber diameter or volume in systole is measured.⁹ The EF can be measured in the M‐mode or two‐dimensional mode. The EF calculation in the M‐mode, is extensively utilized in clinical practice and pediatric patients.⁹ The measurement of the LV end‐systolic diameter (LVESD) and LV end‐diastolic diameter (LVEDD) are made just below the mitral valve leaflets in the parasternal long‐axis view (Figure 1). EF (%) = [(LVEDD³ − LVESD³)/LVEDD³] × 100.¹³ Quantitative EF measurements are crucial in the treatment of severely ill adults and pediatric patients¹⁴, ¹⁵ and can be used alongside the patients’ preload, cardiac output and tissue perfusion to optimize the management of inotropic agents¹⁶ and provide care to hemodynamically unstable pediatric patients.¹⁷, ¹⁸ The EF is classified as normal (EF ≥ 55%), slightly reduced (EF 41%–55%), moderately reduced (EF 31%–40%) and greatly reduced (EF ≤ 30%).¹³

Figure 1.

M‐mode in parasternal long axis.

Assessment of cardiac output and cardiac index

The management of the optimal fluid and inotropic–vasopres‐ sor–inodilator therapy in severely ill pediatric patients should be planned by calculating cardiac output while conducting fluid therapy and inotrope treatment in children with shock,¹⁹ especially in shock conditions which result in high mortality and morbidity in severely ill children.²⁰ The rate of CCE use in cardiac output assessments was 31% in Turkey PICUs.⁶ The latest two septic shock guidelines stressed the significance of the cardiac index calculations in treatment plans.²¹, ²² The assessment of cardiac output by CCE requires two measurements: the diameter of the LV outflow tract (LVOT) in the parasternal long axis view (Figure 2) and the LVOT‐velocity time integral (LVOT‐VTI)measured with pulsed‐wave Doppler below the aortic valve in the apical four chamber view (Figure 3). Stroke volume (SV) is calculated using these measurements and multiplied by heart rate (HR) to calculate the cardiac output [CO = (HR × LVOT‐VTI × (LVOT² × 3.14)/4].²³ Cardiac index is determined by dividing the CO by the body surface area (calculated from height and weight) of the patient. The ideal cardiac index in children with septic shock, recommended by Surviving Sepsis Campaign, is between 3.5 and 5.5 L/min/m².²⁴

Figure 2.

Measurement of of LVOT in the parasternal long axis.

Figure 3.

LVOT‐VTI measurement by using Doppler ultrasound.

Pulse index Contour Cardiac Output (PiCCO) is an invasive gold standard for measurement of cardiac output.²⁵ We have demonstrated that cardiac index measurements by CCE compare favourably with PiCCO measurements and may be as important as invasive PiCCO‐monitoring measurements in the planning of the vasopressor–inotrope and fluid treatment for the severely ill pediatric patients.²⁰

Assessment of volume status

Pediatric patients in the PICUs have a greater risk of hemodynamic instability and it is crucial to determine preload and planning suitable for parenteral fluid therapy for them. Fluid resuscitation is a substantial part of the early control of shock. Correct fluid therapy is essential in decreasing the risk of mortality and morbidity related to multiple organ failure²⁶ and CCE can provide information on volume status and fluid responsiveness.²⁷ There are two methods to assess volume status and fluid responsiveness with CCE. The first is to examine inferior vena cava (IVC) diameter. IVC is highly sensitive to fluid changes and changes in intrathoracic pressure. The vessel collapses with inspiration and opens with expiration during spontaneous breathing. The IVC diameter provides an evaluation of the patients’ fluid status. The evaluation of IVC diameter by POCUS is fast, non‐invasive and easy.²⁶, ²⁸ IVC collapsibility (in spontaneously breathing patients) and IVC distensibility (in mechanically ventilated patients) indices are measured through bedside POCUS.²⁹, ³⁰ Fluid responsiveness can also be estimated by examining the respiratory change in the aortic peak flow velocity on Doppler during inspiration and expiration in those under mechanical ventilation.²⁷

Assessment of pericardial effusion and pericardial tamponade

Pericardial effusions are often assessed using CCE (Figure 4) which can also be used to guide treatment³¹ and identify pericardial tamponade, which is an emergency cause of obstructive shock. CCE can be used to guide pericardiocentesis.³²

Figure 4.

Pericardial effusion adjacent ot the posterior wall in low parasternal long axis view.

Cardiopulmonary resuscitation

Ultrasonography is beneficial in cardiopulmonary resuscitation in determining the reversible reasons for cardiac arrest,³³ but a study of 23 adults with cardiac arrest in the emergency department reported that POCUS use during cardiopulmonary resuscitation caused prolonged pulse check times and postponed high‐quality chest compressions.³⁴ Long et al.³⁵ found that the use of POCUS did not improve survival in cardiac arrest and they did not recommend transthoracic ultrasonography to be used regularly in cardiac arrest, especially for shockable rhythms. In conclusion, CCE is widely used and growing among pediatric intensive care specialists and is important and beneficial for pediatric intensive care patients. We aim to become more familiar with POCUS and CCE techniques which quickly respond to our acute problems in haemodynamically unstable patients and help pediatric intensive care specialists to become more effective in PICUs.

Author contributions

Dincer Yildizdas: Conceptualization (equal), supervision (lead), writing ‐ original draft (equal) and writing – review and editing (lead).

Nagehan Aslan: Conceptualization (equal), and writing – original draft (lead).

Funding

There are no funding sources.

Conflict of interest

The authors declare no conflict of interest.