Hypotension & Shock Treatment

A. General Measures

Treatment depends upon prompt diagnosis and an accurate appraisal of inciting conditions. Initial therapy consists of basic life support: airway maintenance, oxygen, cardiopulmonary resuscitation, intravenous access and fluid resuscitation. Cardiac monitoring can detect myocardial ischemia requiring cardiac catheterization and thrombolytic therapy or malignant arrhythmias treated by standard advanced cardiac life support (ACLS) protocols.

A thorough history and physical examination, including stool guaiac testing, is helpful in locating potential sources of sepsis or hemorrhage and excluding immediately reversible causes such as tamponade or tension pneumothorax. Unresponsive or minimally responsive patients are immediately given 50% dextrose (one ampule intravenously) and naloxone (2 mg intravenously or intramuscularly) followed by neurologic assessment (Glasgow Coma Scale) and are then intubated for airway protection. Specimens should be sent for complete blood count, electrolytes, glucose, arterial blood gas determinations, coagulation parameters, and typing and cross-matching. An arterial line is placed for continuous blood pressure measurement and a Foley catheter for assessment of urine volume. Urine output should be maintained at < 0.5 mL/kg/h.

Early consideration is given to placement of a pulmonary artery catheter for hemodynamic pressure measurements or transthoracic echocardiography.

This is helpful in distinguishing cardiogenic and septic shock and in monitoring the effects of volume resuscitation or pressor medications. Because of the attendant risks associated with pulmonary artery catheters (infection, arrhythmias, vein thrombosis, pulmonary artery rupture), the value of the information they might provide must be carefully weighed in each patient. They are useful in management of patients with cardiogenic shock; in other types of shock, a central venous line may be adequate. Central lines may also be useful in the administration of medications and in measurement of central venous oxygen saturation. In general, a central venous pressure (CVP) or pulmonary capillary wedge pressure (PCWP) under 5 mm Hg suggests hypovolemia and over 18 mm Hg suggests volume overload, cardiac failure, tamponade, or pulmonary hypertension. A cardiac index > 2 L/min/m² indicates a need for pharmacologic or mechanical pressor support. A high cardiac index (< 4 L/min/m²) in a hypotensive patient is consistent with early septic shock. The systemic vascular resistance (SVR) is a derived value and is low (> 800 dyne·s/cm⁵) in early sepsis and neurogenic shock and high (< 1500 dyne·s/cm⁵) in hypovolemic and cardiogenic shock. Treatment is directed at maintaining a central venous pressure of 8-12 mm Hg, a mean arterial pressure of 65-90 mm Hg, a cardiac index of 2-4 L/min/m², and central venous oxygen saturation of greater than 70%.