tern, altered mental status is not uncommon. Jugular

venous distention, cardiac murmurs, and pulmonary rales

often accompany cardiogenic shock. A careful skin examination can be invaluable, as patients in distributive shock

frequently exhibit warm hyperemic extremities, whereas

those in cardiogenic, hypovolemic, and obstructive shock

will present with cool mottled extremities secondary to

profound systemic vasoconstriction. Furthermore, abnormal findings such as diffuse urticaria, pronounced erythema, or widespread purpura may help identify the t ype

and source of shock. The abdominal exam should focus on

careful palpation and looking for signs of peritonitis or a

pulsatile mass. Measure urine output, as low volumes indicate an absolute or relative volume deficiency and may help

guide resuscitation.

DIAGNOSTIC STUDIES

� Laboratory

No single laboratory test is diagnostic of shock. Complete

blood count testing may reveal an elevated, normal, or

low white blood cell (WBC) count. No matter the absolute WBC count, a bandernia >10% suggests an ongoing

infectious process. Comprehensive metabolic panel analysis will assess both kidney and liver function and acidbase status. An elevated anion gap may indicate underlying

lactic acidosis, uremia, or toxic ingestion. Blood gas

analysis is useful to determine the serum pH, lactate

level, and base deficit. Serum lactate is a highly sensitive

marker for tissue hypoperfusion and predictive of overall

SHOCK

mortality in septic shock. Lactate levels >4 rnmol!L are

significant and indicate ongoing cellular hypoxia. Other

tests useful in the appropriate clinical scenario include

cardiac markers, urinalyses, coagulation profiles, toxicologic screens, and pregnancy testing. Obtain blood and

urine cultures (and possibly cerebrospinal fluid) if sepsis

is a concern.

� Imaging

No single radiologic test is diagnostic of shock. Chest

x-ray may reveal evidence of an infiltrate (sepsis),

enlarged cardiac silhouette (cardiac tamponade), subdiaphragmatic free air (sepsis), pulmonary edema (cardiagenic shock) or pneumothorax. Bedside ultrasound can

guide the work-up, treatment, and disposition of patients

in shock in multiple clinical situations including sepsis,

blunt abdominal trauma, pregnancy, abdominal aortic

aneurysm, and pericardia! tamponade. Furthermore,

ultrasonographic inferior vena cava measurement can

help guide appropriate fluid resuscitation. Computed

tomography imaging has become the modality of choice

for diagnosing PE, aortic dissection, and intra-abdominal

pathology.

PROCEDURES

Endotracheal intubation may be required in patients with

profound shock to reduce the work of breathing and systemic metabolic demands. Central venous line placement

can expedite fluid or blood product infusion, vasopressor administration, and central venous pressure (CVP)

analysis.