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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