Critical Care Trauma Centre


Question of the Week: January 14, 2000

Describe the significant finding on the following arterial pressure waveform?



Pulsus Alternans.


  • Every other arterial pressure wave has a decreased systolic blood pressure.
  • The R - R interval on the ECG and systolic - systolic interval on the arterial line are regular, ruling out arrhythmia as the cause for the fluctuating systolic pressure.
  • Considered a significant difference if there is a 20 mmHg difference between alternating systolic pressures.
Generally caused by severe left ventricular failure or pericardial effusion.

Pulsus alternans in a pulmonary artery tracing can indicate severe right ventricular failure.

Brenda Morgan: January 14, 2000


Daily, E., & Schroeder, J. (1994).  Techniques in Bedside Monitoring.  Mosby: Toronto. p. 23, 202, 155-54, 157.

Return to Main Page