The vulnerable microcirculation in the critically ill pediatric patient

Abstract

In neonates, cardiovascular system development does not stop after the transition from intra-uterine to extra-uterine life and is not limited to the macrocirculation. The microcirculation (MC), which is essential for oxygen, nutrient, and drug delivery to tissues and cells, also develops. Developmental changes in the microcirculatory structure continue to occur during the initial weeks of life in healthy neonates. The physiologic hallmarks of neonates and developing children make them particularly vulnerable during critical illness; however, the cardiovascular monitoring possibilities are limited compared with critically ill adult patients. Therefore, the development of non-invasive methods for monitoring the MC is necessary in pediatric critical care for early identification of impending deterioration and to enable the initiation and titration of therapy to ensure cell survival. To date, the MC may be non-invasively monitored at the bedside using hand-held videomicroscopy, which provides useful information regarding the microcirculation. There is an increasing number of studies on the MC in neonates and pediatric patients; however, additional steps are necessary to transition MC monitoring from bench to bedside. The recently introduced concept of hemodynamic coherence describes the relationship between changes in the MC and macrocirculation. The loss of hemodynamic coherence may result in a depressed MC despite an improvement in the macrocirculation, which represents a condition associated with adverse outcomes. In the pediatric intensive care unit, the concept of hemodynamic coherence may function as a framework to develop microcirculatory measurements towards implementation in daily clinical practice.

Preservation of myocardial contractility during acute hypoxia with OMX-CV, a novel oxygen delivery biotherapeutic

“…This excessive O 2 release has been shown to cause oxidative stress to the tissues through the production of toxic reactive oxygen species (ROS) and to induce detrimental microvascular shunting mechanisms that may inappropriately impair tissue perfusion. Delivery of excess O 2 in the setting of shock is a frequent contributor to microcirculatory shunting with significant clinical consequences [ 31 ]. While vascular indices can frequently be normalized within the macrocirculation in the setting of shock, tissue perfusion can nevertheless be compromised because of shunting at the microcirculatory level.…”

Childhood Obesity, Endothelial Cell Activation, and Critical Illness

“…Several studies reported associations between poor outcomes and EA in critically ill children ( 63 – 67 ). Likewise, the link between childhood obesity and poor outcomes in critical illness is well-established ( 68 – 71 ).…”

Endothelial Cell Function and Dysfunction in Critically Ill Children

“…16 The term hemodynamic coherence refers to jointly functioning or dysfunctional macrovascular and microvascular blood flow (eg, normal blood pressure and normal CRT or low blood pressure and prolonged CRT). 17 In critically ill children, hemodynamic coherence may break down, and macrovascular parameters may not reflect microvascular flow at the cellular level, classically illustrated by the low blood pressure and flash CRT state of toxic shock syndrome. Arteriolar EC dysfunction results in pathologic vasoregulation and maldistribution of blood flow manifest as flash or prolonged capillary refill.…”