Respiratory Failure

In respiratory failure, the lungs are unable to perform their job of gas exchange.  In gas exchange, oxygen is transferred from the air into the blood to be carried to different organs and carbon dioxide is expelled from different organs of the body.  Oxygen is required by every tissue of the body.  When oxygen supply is insufficient, tissue death can occur.  This is a life-threatening condition, leading to severe shortness of breath, confusion, unconsciousness and death. 

Causes

Respiration or air exchange is a complex process which is controlled by specialized cells in the brain and facilitated by muscles, lungs and blood vessels.  Basic air exchange happens in the small air sacs or alveoli.  Air is pulled into the air sacs through the airways by the muscles of the chest wall and diaphragm.  The rib muscles and the muscles of the neck also help in the process.  These muscles, called the respiratory muscles, are controlled by the respiratory center in the brain, which in turn, is influenced by cells which are sensitive to oxygen and carbon dioxide levels in the blood. The decrease in oxygen, or increase in carbon dioxide in the blood, leads to stimulation of these cells, which causes the respiratory muscles to contract more.  Malfunction of any part of this chain can lead to respiratory failure.  

1)      Air moves into the alveoli but air exchange or transfer of oxygen does not take place because of thickening of the wall that separates air and the blood.

a.      Interstitial fibrosis

b.      ARDS

c.      Pulmonary embolus

2)     Air cannot be moved in and out of the lung. 

a.      Stroke- where the respiratory area of the brain does not work

b.      Drug overdose or alcohol poisoning- where the respiratory control is depressed

c.      Polio, Myasthenia Gravis- where muscles become too weak to move air in and out

d.      Chest wall trauma leading to lung collapse

e.      Alveolar disease lung COPD or asthma