ADJUSTMENT OF LUXG SHIELD 



I'D!) 



off and keep the aneurism needle from entering the chest 

 cavity proper. Beside this aneurism needle insert another 

 in the same opening and pull the sides of the opening thus 

 made far enough apart to insert the bent end of the glass 

 tube shown in Fig. 201. Be sure the pleura does not close 

 the inner end of the tube. This is the most common source 

 of failure in this experiment. The edge of the lung may 

 also move up when inflated and close the tube. Watch this. 

 With hemostats clamp the glass tube (catching the 

 strings) air-tight in the chest wall. Now close the chest 



Fig. 200. Lung shield made of thin sheet brass with a wire rim soldered around 

 the edge to add strength. A little more than one-half natural size. The large notch 

 passes down over the pedicle of the right lung. To the right of the large notch is seen 

 a grooved channel for the passage (mesially) of the inferior vena cava. (For method 

 of use see text.) 



and fasten it air-tight either with hemostats or by sewing. 

 Connect the glass tube to a large bowled recording tam- 

 bour. This records the lung volume changes. The record 

 should be about two to three inches high. The adjustable 

 by-pass may be opened to allow excess air (which the tam- 

 bour can't hold) to escape. (Air also will then enter the 

 by-pass again when the lungs collapse. This exchange is 

 approximately constant, however, with regular artificial 

 respiration and will not interfere with the validity of the 



