Factors of Excessive Artificial Respiration. 131 



of muscle. Precipitates of calcium phosphate are rapidly dis- 

 solved by acids, and would dissolve slowly in neutral calcium- 

 free solutions. In view of these considerations I propose to 

 devote some time to the study of the osmotic properties of calcium 

 phosphate precipitates, as well as to those of precipitates of 

 calcium carbonate and of magnesium phosphate and magnesium 

 carbonate. 



86 (782) 



The mechanical factors of excessive artificial respiration and a 

 consideration of their relation to the acapnial theory of shock. 



By H. H. Janeway and E. M. Ewing. 



[From the Department of Physiology, Univeristy and Bellevue 

 Hospital Medical College.} 

 It has been claimed that the most important factor in the 

 causation of shock is diminution of CO2 within the blood, and 

 that this diminution is a regular consequence of all influences 

 resulting in shock. That C0 2 possesses important physiological 

 functions cannot be denied. An investigation therefore of the 

 true significance of a diminution of its normal amount within the 

 blood is important and bears a special relation to various methods 

 of artificial respiration utilized in thoracic surgery. The present 

 experiments were undertaken for the purpose of investigating the 

 effects of acapnia and the relation of some factors concerned in its 

 production to shock. In all of them dogs were used. The first 

 series was performed for the purpose of studying the effect 

 of variations 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 cardiometer in series with a record- 

 ing tambour. The blood pressure was recorded from the 

 carotid artery. The thorax was closed and the animal was 

 subjected to intratracheal insufflation from an apparatus pro- 

 vided with an exhaust valve which reduced the pressure to 

 approximately zero about four (4) to twelve (12) times per 

 minute. The blood pressure averaged 150 mm. Hg. when the 

 intrapulmonic air pressure was not allowed to exceed 6 mm. Hg. 



