THE RELATION OF ACAPNIA TO SHOCK, AND A 

 CONSIDERATION OF THE MECHANICAL 

 EFFECTS OF ARTIFICIAL HYPER- 

 RESPIRATION UPON THE 

 CIRCULATION 



HENRY H. JANEWAY and EPHRAIM M. EWING 



(Laboratories of Experimental Surgery and Physiology of the New York 

 University and Bellevue Hospital Medical School^) 



It has been claimed that the most important factor in the causa- 

 tion of shock is diminution of the carbon-dioxide content in the 

 blood and that this diminution is a regulär consequence of all influ- 

 ences resulting in shock. That carbon dioxide exercises significant 

 physiological f unctions cannot be denied ; determination, theref ore, 

 of the true significance of the diminution of its normal proportion 

 in the blood is important and bears a special relation to the various 

 methods of artificial respiration utilized in thoracic surgery. 



This study was undertaken for the purpose of investigating the 

 relation of acapnia to shock. All experiments were performed on 

 dogs. 



The first series of experiments was conducted for the purpose 

 of studying the effect of Variation- in intrapulmonic air-pressure 

 upon the blood-pressure. The thorax was opened laterally, a T-tube 

 connected with a water-manometer was tied in a small bronchus, and 

 the heart enclosed in a Henderson cardimeter connected with a 

 recording tambour. The blood-pressure was recorded from the 

 carotid artery, The thorax was then closed and intratracheal insuf- 

 flation was given from an apparatus provided with an exhaust valve, 

 which reduced the pressure to approximately zero from four to 

 twelve times per minute. When the machine was running at a pres- 

 sure of 6 mm. of Hg there was an average rise of blood pressure 

 of 15 mm., each time the exhaust valve operated. 



* The work presented in this paper was begun in the Laboratory of Biological 

 Chemistry of Columbia University, at the College of Physicians and Surgeons; 

 BiocHEMicAL Bulletin, 1912, ii, p. 175. 



403 



