LIFE-SAVING

Waikato Times, Volume 117, Issue 19545, 6 April 1935, Page 20 (Supplement)

LIFE-SAVING

ARTIFICIAL RESPIRATION. VARIOUS METHODS DESCRIBED. NEED FOR EFFICIENCY. No. V. Before describing the various methods of artificial respiration it may be advisable to briefly describe the structure of the human chest and explain how respiration and circulation are carried out. The chest or thorax is a conical shaped cavity surrounded by the ribs which pass from the spine at the back to the breast-bone in front. It contains the heart, the lungs and the air pipes leading to them, 'the 'large blood vessels and the gullet (food pipe), and It is separated ‘from the abdomen by an arched muscle known as the diaphragm. The heart, a hollow muscular organ about the size of a clenched first, is situated in the chest immediately above the diaphragm, behind the breastbone, between the lungs and slightly to the left of the middle line of the 'body. It is divided into two parts, and each part 'has an upper and a lower chamber, the upper being called auricles and the lower ventricles. The lungs, which occupy the whole of the chest except the part occupied by the heart, bloodvessels gullet, are highly elastic and lie on eaoh side of the chese behind the ribs. The trachea or windpipe phases down the front of the neck from the larynx Into the chest, where It divides into two branches, one for each lung. These branches, which are known as bronchi, divide and subdivide when they are in the lungs Into numerous smaller branches known as bronchial tubes which expand at their terminals into little air cells and over which is spread a network of capillary blood vessels. The pleura is a double membranous bag the outer bag of which lines the chest while the Inner covers the lungs. The venous or Impure blood contains carbonic acid which It accu-

mutates In Its circulation round the body and therefore, beng deficient In oxygen, It Is no longer oapable of nourishing the tissues. This blood Is returned by veins through the superior venua cava and. Inferior vena cava to the right auriole of the heart and from there it Is pumped Into the right ventricle and through the pulmonary artery to the lungs. Air breathed through the nose passes down the trachea and bronchi and through the bronchial tubes to the air cells in the lungs and from this the blood is recharged with oxygen. After Its passage through the lungs the blood passes back through the pulmonary veins to the left auricle of the 'heart, and from there to the left ventricle, whence it Is conveyed through the aorta Into arteries to all parts of the body. The action of the heart In thus propelling the blood is by alternate contraction and delation. The contraction of the two auricles is simultaneous and Is immediately followed by that of the two ventricles. Asphyxia, examples of which are afforded by drowning, suffocation, choking, and as the consequence of electric shock is caused by a deficient supply of air to the lungs. The oxygen gradually diminishes while the carbonic acid Increases until the air In the lungs becomes too impure to purify the blood and venous instead of arterial blood ,in circulated back through all parts of the body. This reaches the brain and renders it Inactive. Shortly insensibility ocours, the face becomes dark and the heart eventually ceases to beat.

Respiration or breathing Is divided into two parts—lnspiration and expiration—brought about by alternate expansion and contraction of the chest. Inspiration is brought about by expansion of the chest when air rushes in through the trachea and fills the lungs. It is chiefly a muscular act, the ribs are raised, the arch of the diaphragm falls and 'becoming flattened increases the capacity of the chest. In expiration, which is brought about largely through the resiliency or the lungs, chest and abdomen, the ribs fall and the arch of the diaphragm rises, thus reducing the capacity of the chest and forcing out impure air. A pause follows the expiration. However, even after expiration a large quantity of air remains in tho lungs and this can he partly expelled by pressure on the chest and abdomen. When this pressure is released air again enters the lungs. (To be Concluded).