26540_CH04_pepp.qxd 3/2/06 9:11 AM Page 83 Hypovolemic Shock 83 Table 4-2 Summary of Different Types of Shock Shock Type Physiologic Insult Common Causes Treatment Hypovolemic Volume loss Hemorrhage Rapid transport Gastroenteritis (vomiting, diarrhea) IV fluid boluses Burns Prolonged poor fluid intake Distributive Decreased vascular tone Sepsis Rapid transport Anaphylaxis Fluid administration Drug overdose Epinephrine for anaphylaxis Spinal cord injury (neurogenic shock) Dopamine or epinephrine for septic shock Cardiogenic Heart failure Congenital heart disease Rapid transport Cardiomyopathy Cautious crystalloid fluid administration, Dysrhythmia 10 mL/kg Drug overdose Consider a vasopressor like dopamine, dobutamine, or epinephrine Obstructive Obstructed blood flow Pericardial tamponade Rapid transport Pneumothorax Needle thoracostomy Fluid administration myocardial function, and vascular stability are out-of-hospital setting. Bleeding from all determinants of effective systemic cardiovas- blunt injuries such as falls or vehicle colli- cular function. If any one of these factors is sions with the child as a pedestrian, bicy- impaired by illness or injury, the body will clist, or passenger is the most frequent attempt to compensate and normalize perfusion cause of hypovolemia. Vomiting and diar- through modification of other physiologic com- rhea from gastroenteritis is a second com- ponents. This is reflected in the clinical signs mon cause. of decreased perfusion, such as tachycardia, The signs and symptoms of hypovolemic vasoconstriction, and increased myocardial shock vary with the amount, duration, and contraction. timing of fluid loss. As intravascular volume There are four general classes of shock— is further compromised by ongoing fluid hypovolemic, distributive, cardiogenic, and losses (such as profuse diarrhea), the child obstructive (Table 4-2)—reflecting impairment may progress from compensated to decom- of the three major functional components of pensated shock. circulation: the blood volume, the vascular sys- tem, and the heart. Studies of hypovolemia— Early (Compensated) the most common type of pediatric shock— Hypovolemic Shock have allowed researchers to describe the clinical signs that characterize the progression Children who lose bodily fluids through of shock from a compensated state (adequate minor blood loss or dehydration from gas- systolic blood pressure) to an uncompensated troenteritis usually show no clinically signifi- state (hypotension). However, the clinical cant effects on circulation. However, if fluid signs characterizing the progression of distrib- losses are more than about 5% of body utive, cardiogenic, or obstructive shock are less weight, the body compensates for decreased well defined. This reflects the complex physi- blood flow by predictable adjustments in car- ology of these other forms of shock. diovascular physiology. This is compensated shock. Signs of compensated hypovolemic shock are tachycardia and peripheral vaso- Hypovolemic Shock constriction. Vasoconstriction causes the signs of abnormal circulation to skin: delayed Hypovolemia (loss of fluid) is the most capillary refill time, and decreased pulse common cause of shock in children in the strength, poor skin color (pallor or mottling),.