Pulsus paradoxus is an exaggerated fall in a patient’s systolic blood pressure during inspiration by greater than 10 mm Hg.

The fall in systolic blood pressure during inspiration in normal individuals is less than 10 mmHg.

How to check for pulses paradoxus?

Pulsus paradoxus is not checked as you check for radial, brachial, or carotid pulses. It is checked with a blood pressure measuring apparatus and a stethoscope.

Instruments required:

  • a manual blood pressure apparatus (sphygmomanometer) &
  • Stethoscope.

How to check for pulses paradoxus?

Ask the subject or the patient to lie in a semi-recumbent position. Tell the patient to breathe normally.

First, check the patients’ blood pressure as usual. Then, record two systolic sounds as:

  • Inflate the blood pressure cuff to at least 20 mmHg above the patients’ systolic blood pressure.
  • Then, very slowly deflate the blood pressure cuff until you hear the first Korotkoff sound during expiration but not during inspiration.
  • Record the blood pressure reading at this point.
  • Next, continue deflating the blood pressure cuff very slowly until you can hear the first Korotkoff sound during both inspiration and expiration.
  • Record this reading again.
  • Calculate the difference between the two readings.
  • If the difference between the first and the second systolic sound is greater than 10 mmHg, this patient has pulses paradoxus.

What is the significance of pulses paradoxus?

How do you differentiate between the pericardial and non-pericardial causes of pulses paradoxus?

Pulses paradoxus in non-pericardial disease will usually manifest with a drop in systolic and diastolic pressures.  This is in contrast to pericardial disease in which the drop is mainly in systolic pressure, diastolic pressure is usually minimally affected, and thus pulse pressure will be narrower.

What are the causes of Pulsus Paradoxus?

Cardiac causes:

  • Pericardial Causes:
    • Cardiac Tamponade
    • Constrictive pericarditis
  • Non-pericardial causes.
    • RV infarction
    • Restrictive cardiomyopathy

Noncardiac causes:

  • Pulmonary causes:
    • COPD
    • Asthma
    • Pulmonary Embolism
    • B/L Large Pleural Effusion
    • Tension pneumothorax
  • Cardiac compression (Any cause )

The most important cause is Cardiac Tamponade

Note: Cardiac tamponade may occur without pulses paradoxus in the following conditions:

  • Intracardiac shunts
  • Moderate to Severe valvular insufficiency
  • A co-existing disease that significantly increases left or right ventricular diastolic pressure such severe systemic hypertension, aortic stenosis, or cor pulmonale
  • Aortic dissection resulting in pericardial effusion/tamponade
  • Cardiac tamponade in Hypovolemia
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