What is Orthopnea?
Orthopnea is uncomfortable awareness of breathing while lying flat (supine position), which prompts patients to sleep propped up with 3 or more pillows, in a chair, or in a recliner to maintain comfortable breathing. 1
Clinical Definition
Orthopnea manifests as at least one of the following 1:
- Uncomfortable awareness of breathing while in a supine position
- Positioning with 3 or more pillows or in a chair/recliner to maintain comfortable breathing during sleep
- Recurrent supine cough without other known cause (may be an orthopnea equivalent)
When documenting orthopnea, the date of onset and duration should be recorded 1.
Underlying Mechanisms
The pathophysiology of orthopnea involves multiple respiratory changes when transitioning from sitting to supine:
In Heart Failure Patients:
- Expiratory flow limitation (EFL) develops or worsens in the supine position 2, 3
- Increased airway resistance (rising from 4.7 to 7.9 cm H₂O/L×s) 4
- Decreased lung compliance (dropping from 0.08 to 0.07 L/cm H₂O) 4
- Markedly increased diaphragmatic work (pressure-time product rising from 181 to 243 cm H₂O×s/min) 4
- The increased inspiratory effort correlates strongly with orthopnea severity (r=0.80) 4
In COPD Patients:
- Tidal expiratory flow limitation occurs in both seated and supine positions 5
- Dynamic pulmonary hyperinflation increases inspiratory threshold load 5
- Lower end-expiratory lung volume in supine position increases airway resistance 5
Clinical Context
Orthopnea is a cardinal symptom of volume overload and elevated left ventricular filling pressures in heart failure patients 1. It should be assessed alongside other volume status indicators including paroxysmal nocturnal dyspnea, peripheral edema, and weight gain 1.
Important caveat: Orthopnea is not exclusive to heart failure—it occurs commonly in COPD patients and results from different but overlapping mechanisms involving expiratory flow limitation and dynamic hyperinflation 5, 3.