CardiovascularDifficulty 3/5
A patient has a cardiac index of 1.6 L/min/m2, pulmonary artery occlusion pressure of 26 mmHg and systemic vascular resistance of 1,900 dynes/sec/cm-5. Which shock state do these numbers describe?
- ACardiogenic shock, because the pump fails and filling pressures rise behind it
- BDistributive shock, because vascular resistance is abnormal and output is inadequate
- CObstructive shock caused by a tension pneumothorax reducing venous return
- DHypovolaemic shock, because cardiac index is low and filling pressure has fallen
Show answer and rationale
Correct: A. Low cardiac index with a high PAOP and high SVR is the classic cardiogenic pattern: the pump fails, filling pressures rise behind it, and the body compensates by vasoconstricting. Hypovolaemia would show a low PAOP and distributive shock a low SVR.
- D — Hypovolaemia lowers filling pressures; this PAOP is high.
- B — Distributive shock is characterised by a low SVR, not 1,900.
- C — Obstructive shock is possible with high filling pressure but would present with acute deterioration and other signs rather than these steady-state numbers.