RESPIRATION. 555 



the shoulder-blades. Draw forward the patient's tongue, and keep it project- 

 ing beyond the lips ; an elastic band over the tongue and under the chin will 

 answer this purpose, or a piece of string or tape may be tied around them, or 

 by raising the lower jaw the teeth may be made to retain the tongue in that 

 position. Remove all tight clothing from about the neck and chest, especially 

 the braces" .... " To imitate the movements of breathing : Standing at the 

 patient's head, grasp the arms just above the elbows, and draw the arms gently 

 and steadily upward above the head, and keep them stretched upward for two 

 seconds. By this means air is drawn into the lungs. Then turn down the 

 patient's arms, and press them gently and firmly for two seconds against the 

 sides of the chest. By this means air is pressed out of the lungs. Repeat 

 these measures alternately, deliberately, and p'erseveringly about fifteen times 

 in a minute, until a spontaneous effort to respire is perceived, immediately 

 upon which cease to imitate the movements of breathing, and proceed to 

 induce circulation and warmth." 



The restoration of respiratory movements is usually facilitated by periodical 

 traction of the tongue, which acts as a reflex stimulus to the respiratory centre. 



I. THE EFFECTS OF THE RESPIRATORY MOVEMENTS ON THE 



CIRCULATION. 



The respiratory movements are accompanied by marked changes in the cir- 

 culation. If a tracing be made of the blood-pressure and .the pulse (Fig. 140), 

 and at the same time the inspiratory and expiratory movements be noted, it 



FIG. 140. Blood-pressure and pulse tracing showing the changes during inspiration (IN.) and expi- 

 ration (EX.). 



will be seen that the blood-pressure begins to rise shortly after the onset of 

 inspiration, commonly after a period occupied by one to three heart-beats, and 

 reaches a maximum after the lapse of a similar brief interval after the begin- 

 ning of expiration, when it begins to fall, reaching a minimum after the 

 beginning of the next inspiration. During inspiration the pulse-rate is more 

 frequent than during expiration and the character of the pulse-curve is some- 

 what different. 



The Effects on Blood-pressure. The changes in blood-pressure are 

 mechanical effects due to the actions of the respiratory movements. When it 

 is remembered that the lungs and the heart with their great blood-vessels are 

 placed within an air-tight cavity, that the lungs become inflated through the 

 aspiratory action of the muscles of inspiration, and that during inspiration 



