Applied Cardiovascular Physiology in the PICU

Normal cellular function is critically dependent upon oxygen, as evidenced by the relative complexity of the organ systems that have evolved to transport oxygen from the surrounding environment to the cells – namely, the cardiac, respiratory, peripheral vascular, and hematopoietic systems. Cells do not have the means to store oxygen, and are therefore dependent upon a continuous supply that closely matches the changing metabolic needs that are necessary for normal metabolism and cellular function. If oxygen supply is not aligned with these metabolic requirements, hypoxia will ensue, eventually resulting in cellular injury and/or death. In addition to the body’s compensatory mechanisms to augment oxygen delivery to the tissues, most of the management of critical illness is directed at restoring the normal balance between oxygen delivery and oxygen consumption. A thorough understanding of cardiovascular physiology, particularly as it applies to the management of the critically ill child in the Pediatric Intensive Care Unit (PICU) is therefore of utmost importance.