Shock in the operating room.

Many factors may contribute to producing a shock state within the surgical environment. The classic causes of shock--hypovolemia, cardiac failure, and sepsis--occur commonly in the operating room. Additionally, concurrent surgery and anesthesia may contribute to produce clinical shock. Surgery may produce hypovolemia from "third space" loss and/or from blood loss. Some anesthetic drugs, by inhibiting the autonomic nervous system, impair the body's ability to compensate for hypovolemia, cardiac failure, or sepsis. Other entities such as tension pneumothorax, drug allergy, or mechanical factors produced by surgical exposure may contribute to hemodynamic compromise of the patient. Shock that occurs outside the surgical suite may also be produced by a variety of insults. One or more factors may contribute to inadequate tissue perfusion, thus making diagnosis of the cause(s) of shock a clinical challenge. Presented in this review is an anesthesiologist's approach to shock on a macrocirculatory level. Two important concepts are vital to this approach. First, one must act immediately to restore adequate perfusion to the brain and heart when confronted with a patient in shock. This is possible without knowing the specific cause(s) of the poor perfusion. Second, a rapid, accurate diagnosis of the cause(s) must be made if the patient is slow to respond to the initial therapy. Through the use of pulmonary artery catheterization, the factors producing any given shock state may be identified, and appropriate therapy may be instituted and monitored.