200 APPLIED ANATOMY. 



In emphysema the lung, being distended, occupies more nearly the outlines of the 

 pleura and its area of resonance is increased. In pleural effusion it is compressed and even 

 sometimes collapsed. As it shrinks it recedes inward and backward and is pushed 

 from the chest-wall by the layer of fluid (Fig. 217). The pressure of the fluid within 

 causes the intercostal spaces to be obliterated and sometimes even to bulge instead of 

 being depressed. As the expansion of the lung is prevented, the chest does not move 

 on the affected side, or expand with the respiration, as it does on the healthy side. 

 This can be demonstrated by measuring the two sides of the chest. At the end 

 of expiration the affected side will be from i to 3 cm. greater in circumference than the 

 healthy one. If the pleural effusion is on the right side it may push the heart to the 

 left and raise its apex beat and cause it to pulsate beyond the nipple line and even in 

 the axilla. If it is on the left side the costomediastinal sinus (page 196) becomes 

 distended with fluid or plastic lymph and this obscures or conceals the heart' s impulse. 

 If the effusion is very large the heart is pushed over toward the right and its apex 

 beat is seen in the third or fourth interspace on the right side even so far over as 

 the mammary line. 



Should the effusion be purulent it may perforate the chest- wall, or open into the 

 pericardium anteriorly, the oesophagus posteriorly, and into the stomach or peritoneal 

 cavity below. If it perforates the chest-wall it usually does so anteriorly between the 

 third and sixth interspaces, most often in the fifth. 



Paracentesis. Where the pleural effusion is serous it is usually drawn off by 

 an aspirating needle or trocar. 



For diagnostic purposes a hypodermic syringe needle is often used, as the chest- 

 walls are usually thin enough to allow this to be done, particularly if a suitable spot 

 is chosen and the patient is a child. Care should be exercised not to strike a rib. 

 The spot chosen for puncture may be indicated by dulness on percussion. It may 

 be anywhere, but when a choice is permissible the puncture should be made in the 

 sixth interspace about in the middle or postaxillary line. Another preferred spot is 

 in the eighth interspace, below the angle of the scapula. The sixth interspace may be 

 determined in several ways, viz. : 



1. Begin at the angulus sterni (angle of Ludwig) and follow out the second rib 

 to the parasternal or midclavicular line, thence count down to the sixth rib and 

 follow it to the midaxillary line. 



2. The nipple is in the fourth interspace, follow it to the axillary line and count 

 two spaces down. 



3. The apex beat of the heart is in the fifth interspace, follow it around to the 

 axillary line and take the next space below. 



4. Find the last rib that articulates with the sternum it is the seventh ; follow it 

 around and take the space above. 



5. With the arm to the side the inferior angle of the scapula marks the seventh 

 interspace; take the interspace next above. 



6. A horizontal line at the level of the nipple cuts the midaxillary line in about 

 the sixth interspace. 



7. The lower edge of the pectoralis major touches the side of the chest at the 

 fifth rib. Follow it to the axillary line and go two spaces lower. 



8. By raising the arm the serrations of the serratus anterior muscle attached to 

 the fifth, sixth, seventh, and eighth ribs become visible; that attached to the sixth rib 

 is the most prominent and is attached farthest forward. 



Empyema. When the pleural effusion is purulent, tapping is not sufficient, 

 am drainage is resorted to. It is not considered necessary to open the pleural 

 cavity at its lowest part but the sites chosen are usually the sixth or seventh inter- 

 space in the mid- or postaxillary line. The movements of the scapula are apt to 

 interfere with drainage immediately below its angle, hence the opening is usually 

 made farther forward. The surgeon may or may not resect a rib. 



The ribs may He so close together as to compress the drainage-tube; in such 

 case a resection is done if the patient's condition permits. 



Incision for Empyema. In certain cases the condition of the patient may 

 demand that as little as possible be done, and that quickly. The point of operation 

 is selected by one of the guides already given, perhaps the level of the nipple. 



