What is Bronchial asthma | cardiac asthma

Bronchial asthma

Introduction

Bronchial asthma is the respiratory disease characterized by difficult breathing with wheezing.

Wheezing-

Wheezing refers to whistling type of respiration. It is due to bronchiolar constriction, caused by spastic contraction of smooth muscles in bronchioles, leading to obstruction of air passage.

 Obstruction is further exaggerated by the
edema of mucus membrane and accumulation of mucus in the lumen of bronchioles.

Causes of bronchial asthma

1. Inflammation of air passage: 

Leukotrienes released from eosinophils and mast cells during inflammation cause bronchospasm.

2. Hypersensitivity:

Hypersenstivity of afferent glossopharyngeal
and vagal ending in larynx and afferent trigeminal endings in nose:
Hypersensitivity of these nerve endings is produced by some allergic substances like foreign proteins.

3. Pulmonary edema and congestion of lungs caused by left ventricular failure: 

Asthma developed due to this condition is called cardiac asthma.

Features of bronchial asthma-

Asthma is a paroxysmal (sudden) disorder because the attack commences and ends abruptly.
During the attack, the difficulty is felt both during inspiration and expiration.

Bronchioles have inherent tendency to dilate
during inspiration and constrict during expiration. So, more difficulty is experienced during expiration.

During expiration, great effort is exerted by all the expiratory muscles causing compression of chest.

Production of whistling sound-

There is severe contraction of abdominal muscles also. So, air from lungs is pushed through the constricted bronchioles,
producing a whistling sound.

Because of difficulty during expiration, the lungs are not deflated completely, so that the residual volume (RV) and functional residual capacity (FRC) are increased.

There is reduction in:
 i. Tidal volume (TV)
 ii. Vital capacity (VC)
 iii. Forced expiratory volume in 1 second (FEV1)
iv. Alveolar ventilation
v. Partial pressure of oxygen in blood.

Carbon dioxide accumulates, resulting in-
• acidosis,
 • dyspnea (shortness of breath) and
 • cyanosis.

Treatment-
• bronchodilators
• anti allergics ( cetrizine)
• use inhaler