Shock

A 53-year-old man with long-standing ischemic cardiomyopathy is admitted to the intensive care unit with hypotension following a 24-hour episode of viral gastroenteritis. He is given intravenous fluids. The following day he develops chest pain, shortness of breath, and mental status changes.

On physical examination, temperature is 38.2 °C (100.8 °F), heart rate is 100/min, blood pressure is 75/45 mm Hg, respiration rate is 12/min, and he is mildly lethargic. Jugular venous pressure is difficult to assess. The lungs are clear. Cardiac examination reveals regular rhythm, a normal S1 and S2, and the presence of an S3. There is peripheral edema bilaterally to the thighs, and the extremities are cool. A pulmonary artery catheter is placed and provides the following data.

Laboratory Studies
Central venous pressure

12 mm Hg (normal, 0-5 mm Hg)
Pulmonary artery pressure

40/15 mm Hg (normal, 20-25/5-10 mm Hg)
Pulmonary capillary wedge pressure

18 mm Hg (normal, 6-12 mm Hg)
Cardiac output

3.5 L/min (normal, 4-8 L/min)

Which of the following is the most likely diagnosis?
A Cardiogenic shock
B Hypovolemic shock
C Septic shock
D Toxic shock

Key Point
The pulmonary capillary wedge pressure is elevated and the cardiac output is low in patients with primary cardiogenic shock.

Answer and Critique (Correct Answer = A)

This patient has cardiogenic shock, manifested by hypotension and evidence of hypoperfusion (decreased mental status, cool extremities). The pulmonary artery catheter data show volume overload—central venous and pulmonary capillary wedge pressures are elevated. The volume overload and low cardiac output are most consistent with cardiogenic shock.

Septic shock and toxic shock are types of distributive shock, result from a severe decrease in systemic vascular resistance, and are often associated with an increased cardiac output and low pulmonary capillary wedge pressure. Although the patient was febrile, the hemodynamic data do not support either septic shock or toxic shock. Hypovolemic shock is associated with reduced pulmonary capillary wedge pressure, cardiac output, central venous pressure, and pulmonary artery pressure. Even though the patient had a bout of viral gastroenteritis that could result in hypovolemia, the hemodynamic data are most compatible with cardiogenic shock.
Bibliography

1. Summerhill EM, Baram M. Principles of pulmonary artery catheterization in the critically ill. Lung. 2005;183:209-19. [PMID: 16078042]