THE PERICARDIUM. 



203 



upward and downward as well as to the sides. When greatly distended the peri- 

 cardium may reach to the first interspace above, 2.5 cm. (i in.) to the right of the 

 sternum, to the seventh cartilage below, and to the left nipple line or even beyond. 

 The arching of the diaphragm causes a sternophrenic sinus behind the sternum anal- 

 ogous to the costophrenic sinus at the lower edge of the chest. This becomes dis- 

 tended by pericardial effusions in the same manner as does the costophrenic sinus in 

 pleural effusions. A puncture in the sixth space close to the left edge of the sternum 

 enters this sinus. The increased area in cases of distention from pericardial effusions 

 has led Osier to advise tapping in the fourth -interspace, either at the left sternal 

 margin or 2.5 cm. from it, or at the fifth interspace 4 cm. (i% in.) from the sternal 

 margin; or by thrusting the needle upward and backward close to the costal margin 

 in the left costoxiphoid angle. 



It is important to avoid wounding the internal mammary artery, which is usually 



FIG. 219. Paracentesis of the pericardium. 



nearer to the sternum above (0.5 to i cm. to its outer side) and farther from it (2 to 

 3 cm. ) below. 



The danger of wounding the pleura in aspirating with a needle has probably 

 been overestimated, but when drainage is to be employed the danger is certain. 



Drainage of the Pericardium. To drain the pericardium requires the 

 removal usually of at least one of the costal cartilages. A drainage-tube can some- 

 times be introduced by first making a short incision in the fifth or sixth interspace 

 close to the left edge of the sternum, then puncturing the pericardium, dilating the 

 puncture with forceps, and introducing the tube. The costal cartilages usually lie so 

 close together as to interfere with the proper introduction of a tube, hence the neces- 

 sity of resection. A flap may be made or a straight incision. The latter is some- 

 times made over the fifth costal cartilage, which is then resected. If desired 

 sixth and seventh cartilages are also removed and even a piece of the left edge of 

 sternum. The intercostal muscles having been raised, the cartilages are remove 



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