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How do we breathe

Stimulus from higher centre situated at brain, leads to contraction of chest wall, lowering of diaphragm and  increase in capacity of thoracic cage, which draws the lung surfaces alongwith it, the lining expands, and air gushes in. This is inspiration.

On next stimulus from brain, the reverse process starts, with relaxation of muscles of chest wall; the diaphragm is raised, capacity of thoracic cage reducess, lungs contract and air is expelled. This is expiration. 

Role of Breathing

The normal rate of breathing is 15-18 times per minute. If more, it indicaes distress, shock, pain, CO2 poisoning.


Oxygen is essential for life, and it constitutes one fifth of normal air, by volume. When we breathe fresh air, its oxygen content goes into the blood in our lungs; as this blood circulates, oxygen reaches all parts of our body. At the same time, CO2 (Carbon dioxide) generated in the body is taken into the blood on its return journey to the lungs, where it is purified once again. The exchange of CO2 / O2 in lungs is explained below: 

During respiration, inhaled air reaches upto the last cell of lungs (ALVEOLI) and comes in contact with terminal ends of blood vessels (capillaries). Here the partition between air and blood is very thin, which allows free passage of gases but not of fluids. Therefore oxygen from fresh air goes into the blood and carbon-di-oxide (CO2), from blood comes to the lungs cells, thus purifying the blood but making the lung air charged with CP2. This impure air is later exhaled.


Acute reduction in fresh air supply to lungs due to any cause is called asphyxia.

Causes of Asphyxia:


1.                    Higher centre of brain affected due to electric shock & gas poisoning.

2.                    Obstruction in respiratory tract due to:

a        Vapour or gases : Noxious mine gases, fumes etc.

          b        Fluids               : Water – drowning cases

          c        Solids               : Food particles




Direct pressure from outside on neck e.g. buried under mass of fallen coal.

Signs & Symptoms

Early Stage


1.                    Shortness of breath

2.                    Weakness, Giddiness

3.                    Rapid pulse

4.                    Semi-consciousness

5.                    Swelling in veins of neck

6.                    Flushed face, bluish lips 

Signs & Symptoms:

Later Stage


1.                    Slow and intermitted breathing

2.                    Slow and irregular pulse

3.                    Lips, nose, ears, fingers & toes turn bluish

4.                    Complete unconsciousness 


1.                    Remove cause, if possible

2.                    Give artificial respiration, immdeiately. Even the slightest delay may be dangerous for the victim.

3.                    Combat shock

Methods of Artificial Respiration

The first-aider can himself give artificial respiration to the victim by four different methods:

1.                    Holger – Nielsen method

2.                    Schafer’s method

3.                    Silvester’s method

4.                    Mouth-to-mouth resuscitation

The methods should be crefully understood; for this practical demonstrations may be arranged; thereafter it should be practiced regularly. Unless the first aider has practiced regularly, he might falter at the time of emergency and fail to revive the victim.

Mechanical resuscitators  are also being manufactured in our country. These resuscitatiors are based on the principle of mouth-to-mouth respiration and come under the brand names of ARYVIVE and LIAF.  The first aider should learn their use. These resuscitators are very effective in case of electric shock or gas poisoning.