Understanding Pulsus Paradoxus

Pulsus paradoxus is a clinical sign characterized by an exaggerated decrease in systolic blood pressure during inspiration—specifically, a drop of more than 10 mmHg. Normally, when you inspire, the increased negative intrathoracic pressure slightly lowers systolic pressure; however, in pulsus paradoxus, this drop is significantly more marked.

Causes pulsus paradoxus

Pulsus paradoxus is primarily associated with conditions that affect the heart, the pericardium (the sac around the heart), and the lungs. Some potential causes of pulsus paradoxus include:

Cardiac causes

• Cardiac tamponade or pericardial effusion: This condition is caused by a build-up of fluid in the pericardium which puts pressure on the heart. This stops the chambers of the heart from filling properly and hence reduces the ability of the heart to pump blood around your body
• Constrictive pericarditis: This is a condition where the walls of the pericardium surrounding your heart stiffen and become too thick, preventing your heart from beating properly
• Restrictive cardiomyopathy: Here, the muscles of your heart ventricles stiffen and cannot fill with blood, reducing blood flow in your heart
• Acute myocardial infarction (heart attack)
• Tricuspid atresia: A congenital condition where you are born without a tricuspid valve in your heart – the valve that controls blood flow from the right atrium to the right ventricle

Pulmonary causes 

• Large pleural effusion: Excess fluid build-up in the pleural cavity (the fluid-filled space that surrounds your lungs)
• Pulmonary embolism: A condition where one of the pulmonary arteries in the lungs is blocked by a blood clot
• Tension pneumothorax (collapsed lung)
• Severe asthma exacerbation
• Chronic obstructive pulmonary disease (COPD)
• Obstructive sleep apnea

Other causes

• Profound hypovolemia
• Superior vena cava obstruction
• Obesity
• Volvulus of the stomach (gastric volvulus)
• Thoracic outlet syndrome

Pathophysiology

• Intrathoracic Pressure Changes: During inspiration, negative intrathoracic pressure enhances venous return to the right side of the heart. In conditions such as pericardial tamponade, this extra blood in the right ventricle causes the interventricular septum to shift toward the left. The resultant encroachment on the left ventricular space reduces its filling capacity and stroke volume, leading to a more pronounced fall in systolic blood pressure during inspiration.
• Conditions Associated: Pulsus paradoxus is most commonly associated with pericardial tamponade. It can also be seen in severe asthma, constrictive pericarditis, and other conditions that impair the heart’s filling by affecting the intrathoracic pressure dynamics.

Clinical Evaluation

• Measurement Technique: Using a manual blood pressure cuff and a stethoscope:
  1. Inflate the cuff until Korotkoff sounds disappear.
  2. Slowly deflate the cuff and note the pressure at which the sounds return only during expiration.
  3. Continue deflating and record the pressure at which audible sounds are heard throughout the respiratory cycle. If the difference between the two pressures exceeds 10 mmHg, pulsus paradoxus is present.
• Significance in Practice: An exaggerated inspiratory drop in systolic blood pressure is an important bedside clue. It alerts clinicians to underlying cardiopulmonary conditions that may require urgent intervention. Recognizing pulsus paradoxus can prompt further diagnostic evaluation, including echocardiography or other imaging studies, to determine the underlying cause.

How to Assess Pulsus Paradoxus

There are several ways to detect and measure pulsus paradoxus. You can use a sphygmomanometer (standard blood pressure cuff), palpate the patient’s radial pulse, or observe the intra-arterial waveform if the patient has an arterial line.

• Using a sphygmomanometer
  • Make sure the patient is breathing normally.
  • Inflate the blood pressure cuff 10 to 20 mm Hg beyond the peak systolic pressure.
  • Then deflate the cuff slowly at a rate of 2 mm Hg/second until you hear the first Korotkoff sound during expiration; note the systolic pressure.
  • Continue to deflate the cuff, observing the patient’s respirations. In pulsus paradoxus, the Korotkoff sounds will disappear with inspiration and return with expiration.
  • Continue to deflate the cuff until the Korotkoff sounds emerge during both inspiration and expiration; note the systolic pressure.
  • Subtract the second systolic reading from the first. A difference of more than 10 mm Hg is abnormal. Peripheral pulses may not be palpable or may disappear completely with a drop in systolic blood pressure greater than 20 mm Hg.
• Palpating the patient’s pulse
  • Palpate the patient’s radial pulse over several cycles of slow inspiration and expiration.
  • A significant decrease in the strength of the pulse during inspiration may indicate pulsus paradoxus.
• Observe the intra-arterial blood pressure waveform
• For a patient in the intensive care unit with an intra-arterial line, you can assess the waveform. With pulsus paradoxus you will see a decrease in the amplitude of the systolic pressure on inspiration. 

Treatment for Pulsus Paradoxus

Pulsus paradoxus is not a condition itself but a clinical sign indicating underlying issues such as cardiac tamponade, severe asthma, or constrictive pericarditis. Treatment focuses on addressing the root cause. Here are the key approaches:

1. Emergency Interventions

• Cardiac Tamponade:
  • Perform pericardiocentesis to remove excess fluid from the pericardial sac and relieve pressure on the heart.
• Severe Asthma or COPD Exacerbation:
  • Administer bronchodilators (e.g., albuterol) and corticosteroids to reduce airway inflammation.
  • Provide oxygen therapy or mechanical ventilation if necessary.

2. Medical Management

• Constrictive Pericarditis:
  • Use diuretics to manage fluid overload and reduce symptoms.
  • Consider surgical intervention, such as pericardiectomy, for severe cases.
• Respiratory Conditions:
  • Treat underlying infections or inflammation with antibiotics or anti-inflammatory medications.

3. Supportive Care

• Monitoring:
  • Regularly assess vital signs and cardiac function to track improvement.
• Fluid Management:
  • Optimize fluid balance to prevent exacerbation of symptoms.

4. Long-Term Management

• Address chronic conditions contributing to pulsus paradoxus, such as asthma or heart disease, through lifestyle modifications, medication adherence, and regular follow-ups.

REFERENCES

1. Van Dam MN, Hashmi MF, Fitzgerald BM. Pulsus Paradoxus. [Updated 2024 Feb 28]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2025 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK482292/
2. Borlaug, B. A. (2019). Pulsus Paradoxus. UpToDate.  https://www.uptodate.com/contents/pulsus-paradoxus-in-pericardial-disease
3. Lippincott Advisor (2020, October 2). Pulsus Paradoxus. Lippincott Solutions. https://advisor.lww.com/lna/document.do?bid=2&did=914524
4. Sarkar M, Bhardwaj R, Madabhavi I, Gowda S, Dogra K. Pulsus paradoxus (https://pubmed.ncbi.nlm.nih.gov/29873194/). Clin Respir J. 2018 Aug;12(8):2321-2331. Accessed 12/29/2022.
5. Van Dam MN, Fitzgerald BM. Pulsus Paradoxus (https://www.ncbi.nlm.nih.gov/books/NBK482292/). 2022 May 1. In: StatPearls [Internet]. Treasure Island, FL: StatPearls Publishing; 2022 Jan-. Accessed 12/29/2022.
6. York, N. L., Kane, C., & Smith, C. S. (2018). Identification and Management of Acute Cardiac Tamponade. Dimensions of critical care nursing: DCCN, 37(3), 130–134. https://doi.org/10.1097/DCC.0000000000000295

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