ORTHOPNEA and PND

 Dyspnoea on lying flat

It is a sign of advanced heart failure

Lying flat increases venous return and in patients with left ventricular impairment may precipitate pulmonary edema.

Lying flat causes a steep increase in left atrial and pulmonary capillary pressure resulting in pulmonary congestion and severe dyspnea.

This severity can be graded by number of pillows used at night.eg -three pillow orthopnea

Causes 1.Biventricular failure 

PND-Paroxysmal nocturnal dyspnea

Sudden breathlessness waking the patient from sleep.caused by accumulation of alveolar fluid.patient may choke or gasp for air , patient open windows in an attempt to relieve their stress

Causes 1.Left heart failure

2.cardiomyopathy

3.Aortic valve disease

Reference -Macleod edition 13 page 102