MECHANICAL PHENOMENA OF EXTERNAL RESPIRATION 229 



being universal; in the uncivilized and semi-civilized races that 

 have been investigated, the women breathe like the men. It is 

 therefore probable that the predominance of the costal type among 

 women of European race is a peculiarity developed by a mode of 

 dressing which hampers the movements of the diaphragm while 

 permitting the elevation of the ribs. This conclusion is strengthened 

 by the fact that in children no difference exists /both boys and girte 

 show the abdominal type of respiration.! 



All this refers to ordinary breathing.- / In forced respiration, when 

 the need for air becomes urgent, costal breathing always becomes 

 prominent alike in men, in women, and in animals, for by elevation 

 of the ribs the capacity of the chest can be increased to a greater 

 degree than by any contraction of the diaphragm. 



In forced inspiration, indeed, all the muscles that can elevate the 

 ribs may be thrown into contraction, as well as other muscles which 

 give these fixed points to act from. During a paroxysm of asthma, 

 for example, the patient may grasp the back of a chair with his 

 hands, so as to fix the arms and shoulders and allow the pectorals 

 and serratus magnus to raise the ribs. Similarly in forced expiration 

 all the muscles are used which can depress the ribs, or increase the 

 intra-abdominal pressure and push up the diaphragm. 



Artificial Respiration. An efficient pulmonary ventilation can be 

 obtained by various methods when the natural breathing is in abey- 

 ance. In animals the method most commonly employed for ex- 

 perimental purposes is the rhythmical inflation of the lungs by a 

 pump or bellows, or by a stream of compressed air which is regularly 

 interrupted, the chest being allowed to collapse after each inflation. 

 When the animal is to be kept alive after the experiment the inflation 

 is produced through a tube introduced through the glottis. If the 

 animal is not to be kept alive, the apparatus is generally connected 

 with a cannula in the trachea. In man the exchange of air between 

 the atmosphere and the lungs may be most readily accomplished 

 by strong rhythmical compression of the lower part of the chest. 

 This forces out some of the air from the lungs; on relaxing the 

 pressure the chest expands again and air is drawn in. Schafer has 

 shown that this is the most efficient method of respiration in re- 

 suscitation of the apparently drowned. ' The patient is placed face 

 downwards on the ground, with a folded coat under the lower part 

 of the chest. The operator puts himself athwart or at the side of 

 the patient, facing his head and kneeling upon one or both knees 

 (Fig. no), and places his hands on each side over the lower part 

 of the back (lowest ribs). He then slowly throws the weight of his 

 body forward to bear upon his own arms, and thus presses upon 

 the thorax and forces air out of the lungs. He then gradually 

 relaxes the pressure by bringing his own body up again to a 

 more erect position, but without moving the hands.' Air is thus 



