Differential Diagnosis for Unstable Patient with High Cardiac Output and Low SVR

• Single most likely diagnosis:
  • Septic shock: This condition is characterized by a high cardiac output and low systemic vascular resistance (SVR), often due to the vasodilatory effects of inflammatory mediators released in response to infection.
• Other Likely diagnoses:
  • Anaphylactic shock: Similar to septic shock, anaphylactic shock can present with high cardiac output and low SVR due to widespread vasodilation caused by the release of histamine and other mediators.
  • Neurogenic shock: Typically seen in patients with severe spinal cord injuries, neurogenic shock can result in low SVR due to loss of sympathetic tone, leading to vasodilation.
  • Hepatogenic shock (in cases of severe liver disease): Although less common, severe liver disease can lead to a state of vasodilatory shock, characterized by high cardiac output and low SVR.
• Do Not Miss (ddxs that may not be likely, but would be deadly if missed.):
  • Adrenal insufficiency: Although rare, adrenal insufficiency can present with hypotension and low SVR, and high cardiac output may be seen as a compensatory mechanism. Missing this diagnosis can be fatal.
  • Thyrotoxic crisis: A life-threatening condition that can cause high cardiac output and low SVR due to the excessive effects of thyroid hormones on the cardiovascular system.
• Rare diagnoses:
  • Beri-Beri (Thiamine deficiency): A rare cause of high-output heart failure, which can present with low SVR.
  • Aortic regurgitation: Severe aortic regurgitation can lead to a high cardiac output state, and if associated with significant vasodilation, could present with low SVR, although this is less common in the context of shock.