What are platypnea, orthopnea, and trepopnea?

Definitions of Positional Dyspnea Terms

Platypnea is dyspnea that worsens when upright and improves when lying down; orthopnea is dyspnea that worsens when lying flat and improves when sitting or standing upright; trepopnea is dyspnea that occurs or worsens in one lateral decubitus position but improves in the other lateral position. 1

Platypnea

• Breathing difficulty triggered by standing or sitting upright that is relieved by lying flat (supine position)
• Often accompanied by orthodeoxia (oxygen desaturation >5% or arterial oxygen pressure drop >4 mmHg when upright) 2
• The combination is called platypnea-orthodeoxia syndrome (POS)
• Mechanism: Results from right-to-left shunting through either:
  • Intracardiac pathways (most common): Patent foramen ovale with structural abnormalities like aortic dilation or right atrial compression that redirect blood flow when gravitational forces change with position 2, 3
  • Intrapulmonary pathways: Parenchymal or vascular lung disease 2

Clinical Pitfall

Platypnea is counterintuitive and easily missed because most clinicians expect dyspnea to worsen when lying down (orthopnea), not improve. Patients may have symptoms misattributed to other causes for years before diagnosis 3.

Orthopnea

• Dyspnea that occurs or worsens when lying flat and improves when sitting or standing upright
• Classic cardiac symptom suggesting elevated left atrial pressure or ventricular dysfunction 4
• Commonly associated with:
  • Congestive heart failure
  • Valvular heart disease
  • Pericardial disease
• Patients typically report needing multiple pillows to sleep or sleeping in a recliner

Trepopnea

• Breathing difficulty that is comfortable in one lateral position but labored in the opposite lateral position 1, 5
• Less commonly recognized than orthopnea or platypnea
• Associated with unilateral pathology that creates position-dependent ventilation-perfusion mismatch:
  • Unilateral lung disease (tumor, consolidation)
  • Unilateral vascular obstruction (pulmonary artery stenosis)
  • Unilateral airway obstruction 5
• Pattern: Patients typically prefer lying on the "good lung" side down to optimize perfusion to the better-ventilated lung

Key Diagnostic Approach

When evaluating positional dyspnea, systematically assess oxygen saturation and arterial blood gases in different positions (supine, upright, left lateral, right lateral) to objectively document the positional component 2. This simple bedside maneuver provides critical diagnostic information that directs subsequent imaging and workup.