There have been several references1 in recent journals questioning the advisability of utilizing blood transfusions under pressure because of the possibility of the blood leaving the system too rapidly and air entering the body, with resulting fatal air emboli. It is generally agreed that if the person who is introducing the air under pressure into the transfusion bottle has nothing else to do, he can stop the transfusion before air enters the vein. Recently, however, instances have been reported to me in which during the stress of operating attention was diverted from the transfusion bottle and air entered the recipient's veins, with fatal air emboli resulting.
The device presented here has been designed with the knowledge that it involves no new principle, but it is felt that its use in connection with pressure transfusions is new and can serve as a life-saving safety mechanism. As can be seen from