Table 10.1 compares clinical findings by type of shock including some common examples Hypovolemic Shock Hypovolemia (decreased circulating blood volume) is the most common cause of shock in children Volume losses from vomiting and diarrhea secondary to gastrointestinal infections are the most prevalent etiology of hypovolemic shock worldwide Other causes of hypovolemic shock include hemorrhage (trauma, postsurgical, gastrointestinal), plasma losses (burns, hypoproteinemia, pancreatitis), and extragastrointestinal water losses (glycosuric diuresis, heat stroke) Acute hypovolemia results in decreased cardiac output due to a fall in preload with a compensatory increase in heart rate and SVR A fall in blood pressure detected within the baroreceptors of the carotid sinus leads to an increase in the sympathetic nervous system activity, stimulating cardiac chronotropy and vascular smooth muscle constriction as well as epinephrine release from the adrenal medulla Upregulation of the renin–angiotensin–aldosterone (RAA) system and release of antidiuretic hormone (ADH) from the posterior pituitary gland promote sodium and water retention by the kidneys Angiotensin II is also a direct vasoconstrictor, contributing to the observed increase in SVR Cardiogenic Shock The term cardiogenic shock is generally reserved for a decrease in cardiac output resulting from a decrease in myocardial contractility Shock due to obstruction of blood flow from certain types of congenital heart lesions is better classified as obstructive shock (see below) Although myocardial depression can occur in all forms of shock, primary deficits in myocardial contractility leading to cardiogenic shock are caused by viral myocarditis, anomalous left coronary artery arising from the pulmonary artery (ALCAPA), incessant arrhythmias, drug ingestions (e.g., cocaine), metabolic derangements (e.g., hypoglycemia), and postoperative complications of cardiac surgery Characteristic signs of cardiogenic shock are congestive heart failure, including pulmonary rales, a gallop cardiac rhythm, hepatomegaly, jugular venous distention, pitting peripheral edema, and cardiomegaly on chest radiograph Laboratory findings of elevated creatine kinase, troponin, or brain natriuretic protein (BNP) levels may herald myocardial dysfunction, but are not universally present As in hypovolemic shock, upregulation of the sympathetic nervous system, RAA system, and ADH, as well as the natriuretic peptides (BNP and atrial natriuretic peptide) raises SVR to compensate for a low cardiac output Unlike hypovolemic shock, however, the