CARDIOVASCULAR FUNCTIOXS— D'AMATO 159 



2. Case, R. B., Berglund, E., and Sarnoff, S. J.: Ventricular function. II. Quantitative rela- 



tionsliip between coronary flow and ventricular function with observations on unilateral 

 failure, Circulation Research 2: 319, 1954. 



3. Delorme, E. J.: Experimental cooling of the blood stream. Lancet 263: 914, 1952. 



DISCUSSION 



Dr. Edzvard Uricdmaii: 1 wotild like to present some of the observations on cardio- 

 dynamics made dtiring a recent study of hemorrhagic shock in hypothermic dogs. 

 In table I are data derived from dogs anesthetized with ether and cooled by immer- 

 sion in ice water until the rectal temperature reached 28° C. After a brief period to 

 allow for desaturation of ether, the animals were bled to an arterial pressure of 

 30 mm. Hg. for an average of 7 hours. They were then transfused and rewarmed. 

 Hypothermia lowers the arterial pressure, pulse rate, cardiac output, and pulmonary 

 ventilation, but the oxygen content of the arterial blood is adequately sustained. 



After the induction of shock, the pulse rate falls still further instead of rising 

 as in the normothermic dog. There is a precipitous further decline in cardiac output 

 to 181 cc, thereby reducing the stroke volume to less than 3 cc. With an oxygen 

 consumption of only 20% of normal during shock, the sharp rise in A-V oxygen 

 difiference must signify an almost static peripheral circulation. For this reason, to- 

 gether with the much reduced effect of respiration on return flow, the venous return 

 to the heart is extremely small. The consequently slow flow through the pulmonary 

 circuit explains the adequacy of the very low ventilatory volume for the maintenance 

 of normal arterial oxygen content. Because of the low level of tissue metabolism, 

 hypercapnia does not develop in the face of a depressed respiration. (No significant 

 shift in arterial blood pH was observed in any of our experiments.) 



Following transfusion and rewarming there is a return to normal or nearly nor- 



TABLE I 



Cardiovascular and Respiratory Dynamics in Doss Precooled Under Ether and 

 Subsequently Subjected to Hemorrhagic Shock 



3592 



1909 



181 



3355 22.7 5.5 14.8 123.0 18 



(4) (4) (4) (4) (4) (23) 



