Describing the attack of PND
Normally after 30 minutes to 2 hours of lying in bed for sleep, the patient wakes up with feeling of intense suffocation or chocking sensation. Classically he sits upright gasping in bed with legs hanging by bed or rushes to open the window to get cool air, hoping it will relieve his symptom. Profuse sweating occurs and it may be accompanied by a dry, repetitive cough which is due to ‘ Acute Interstitial edema’. This may resolve with in 30 minutes and sometimes may end fatally.
- There is redistribution of blood volume from the lower extremities and splanchnic beds to the lungs in supine posture. In patients there is a significant reduction in vital capacity and pulmonary compliance with resultant shortness of breath. Additionally, in congestive heart failure the pulmonary circulation may already be overloaded, and there may be reabsorption of edema fluid from previously dependent parts of the body.The failing left ventricle is suddenly unable to match the output of a more normally functioning right ventricle; this results in pulmonary congestion.
- Other theories include decreased responsiveness of the respiratory center in the brain.
- Decreased adrenergic activity in the myocardium during sleep.
Pulmonary congestion decreases when the patient assumes a more erect position, and this is accompanied by an improvement in symptoms.
PND is the earliest symptoms of Acute left heart failure. ‘Cardiac asthma’ is said to be closely related to PND.
Clinical examination at the time of attack of PND:-
a. Severe dyspnea and orthopnea: Tachypnea may be present.
b. Anxious and pale with profuse sweating.
d. Pulse- tachycardia, feeble
e.Blood pressure may be high.
f. Jugular venous pulse is raised.
g.Heart- S3 gallop rhythm can be heard, signs of underlying heart disease.
h. Lungs- Vesicular breath sound with prolonged expiration, Crepitations – basal , ronchi
References: (Bedside Clinics in Medicine, Ncbi.nlm.nih.gov)