DRUGS AND INTERNAL COOLING— DAMMANN and MULLER 



433 



NEEDLE VALVE 



jsmaamnmnai 



SUCTION 



SILASTIC 

 GASKETS 



TEFLON COATED 



PORCELAIN DISC 



(20 MICRON PORE SIZE) 



PORCELAIN DISC 

 (4.4 MICRONS 

 PORE SIZE) 



>SEPARATION 



FIBERGLASS SCREEN 

 ROLL COATED 

 WITH ANTIFOAM 



/COALESCENCE 



/DISPERSION 



SILASTIC 



Fig. 1. — Diagram of a small pump-oxygenator. 



By immersion of the coil in an ice-salt mixture, differential hypothermia (fig. 2) 

 can be rapidly induced in the upper part of the dog's body where the temperature 

 can be lowered to or close to 0° C. This might not be necessary in eventual clinical 

 applications. We did it only to prove that the temperature at which water freezes 

 is not harmful to large, adult, nonhibernating mammals. 



At about 13° C. the last heart beat is recorded (fig. 3) and cardiac arrest can 

 be maintained as long as the temperature is kept that low. The heart is still irritable 

 because mechanical stimulation can elicit a slow contraction at 6° C. On rewarming 

 the blood the heart starts to beat again in sinus rhythm and at about 30° C. the 

 pump-oxygenator can be turned off. 



This technique has the following advantages : it is rapid and clean ; hypothermia 

 is selective for organs perfused w'ith cold blood ; no drifting to lower temperatures 

 takes place ; shivering is minimal or absent ; the volume of the instrument is so small 

 that it can be filled with cold Ringer's solution ; the increased oxygen consumption 

 of rewarmed organs is simultaneously and automatically covered with an adequate 



