AND BLOOD PRESSURE 



145 



If both abdomen and chest participate in the breathing, inter- 

 mediate results will be obtained, one effect will counteract the 

 other ; and if abdomen or chest do not participate to the same 

 relative extent during different instants of a particular act, com- 

 plex curves will result which are beyond analysis. When a patient 

 is asked to take a deep breath, the breathing is often disorderly 



A ABOOMEff 



C ABOOMEH 



BP.L.nt 



D. CHEST 



Flo. 18. Influence of chest and abdominal breathing on the pulse (Lewis). 



in character, starting perhaps as intercostal and finishing as 

 abdominal. 



In man a deep intercostal respiration, if not prolonged, yields a 

 fall of pressure, and conversely a deep diaphragmatic inspiration 

 yields a rise. But as the normal respiratory curves of blood 

 pressure are of very complex origin, and the different factors in- 

 volved vary widely, it is not possible to state what the effect on 

 blood pressure will be, unless the conditions and nature of the 

 respiratory act are known. The ordinary statement in the text- 

 books that inspiration raises and expiration lowers blood pressure 

 is altogether unjustified by the records. The pressure almost 



