AM cards report PEARLS 2/2: pulsus paradoxus and lung whiteout

  • Pulsus Paradoxus does NOT always mean cardiac tamponade! Ddx includes both cardiac (tamponade OR constrictive pericarditis) and noncardiac (from exaggerated changes in intrathoracic pressure during inspiration/expiration – most common causes being severe asthma and emphysema, massive PE)
    • Going back to physiology: even in normal circumstances, our SBP drops with inspiration because inspiration à decrease in intrathoracic cavity pressure à increased venous return to heart à septal bowing into LV reducing systemic outflow. The difference between SBP on inspiration vs expiration can be exaggerated whenever there is an increased fall in pressure on inspiration, or increased rise in pressure on expiration (eg decreased compliance of lung). In tamponade, RV has nowhere to stretch so septum bulges into the LV more.
    • See attached JAMA Rational Clinical Exam article on pericardial effusions and cardiac tamponade – sensitivity and specificity of a pulsus paradoxus are 98% and 70% respectively for a pulsus >10, and 98% and 83% for a pulsus >12!
    • Link to previous AM report PEARLS on pericardial effusions here!
  • Unilateral whiteout on CXR + mediastinal shift:
    • Most common ddx for unilateral whiteout (all comers) = consolidation, pleural effusion, and collapse/atelectasis. Presence of tracheal deviation/mediastinal shift can help in your ddx!!
    • No mediastinal shift: ddx consolidation/pna, small/mod effusion
    • Mediastinal shift AWAY from whiteout = mass effect: large effusion leading to increased pressure on that side of lung (in this case, given the acuity, think about worsening malignant pleural effusion or bleeding into the effusion (eg from anticoagulation)
    • Mediastinal shift TOWARDS whiteout = volume loss: lung collapse, post-pneumonectomy
  • Implications EGFR+ NSCLC – when put on EGFR inhibitors, life expectancy increases by about 2 months

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