Shock and Hemodynamic Instability Flashcards

What is the pathophysiologic mechanism underlying cardiogenic shock?

Answer: Pump failure reduces cardiac output causing tissue hypoperfusion

Cardiogenic shock results from the heart's inability to maintain adequate cardiac output, leading to tissue hypoperfusion despite normal or elevated filling pressures.

Which clinical finding indicates a positive response to a fluid challenge in a hypotensive patient?

Answer: Increase in pulse pressure and improvement in mental status

A positive fluid response is indicated by improved perfusion markers such as increased pulse pressure, improved mentation, and decreased heart rate.

A patient in decompensated shock has cold, mottled extremities and a capillary refill of 5 seconds. What organ is most immediately at risk?

Answer: Kidneys (acute tubular necrosis)

Prolonged hypoperfusion in shock preferentially damages the kidneys, causing acute tubular necrosis and acute kidney injury.

What is the significance of a serum lactate greater than 4 mmol/L in a shock patient?

Answer: Indicates severe tissue hypoperfusion and high mortality risk

A lactate >4 mmol/L reflects severe anaerobic metabolism from tissue hypoperfusion and is associated with significantly increased mortality.

Which intervention is definitive for obstructive shock caused by tension pneumothorax?

Answer: Needle decompression followed by chest tube thoracostomy

Needle decompression (2nd ICS MCL or 4th/5th ICS AAL) releases trapped air, converting tension pneumothorax to simple pneumothorax, followed by chest tube.

Which parameter is most useful for determining if a patient will respond to fluid resuscitation?

Answer: Passive leg raise test with cardiac output monitoring

The passive leg raise (PLR) test predicts fluid responsiveness by temporarily increasing venous return; a rise in cardiac output confirms preload responsiveness.