A Technique For Highly Oxygenated Crystalloid Cardioplegia Delivery

____________ _ (/. Extra-Corpor. Techno/. 20[ 1]: p. 35-39 Spring 1988) Development of a new cardioplegic solution (oxygenated crystalloid) and method of delivery is discussed from in vivo and in vitro testing and clinical use in over 4000 clinical cases. Assemblage of existing components into a new and safe device is presented. Introduction _____________ _ Since the onset of cold potassium cardioplegia as a standard practice, a myriad of refinements to this technique has taken place over the last few years. Originally, temperature of the potassium solutions was the controversial topic; however, this debate finally subsided at our center and acceptable ranges were settled on from 4-8 oc. 1 The subject of temperature brought with it the question of which technique for cooling the solution was best: coil (polyvinyl chloride or metal), heat exchanger, or other methods. Another area of concern was the method of delivery. At our institutions, the initial method of choice (no longer used), was the syringe technique, administered via a 60 ml syringe into the aortic root by the surgeon. We, as well as the surgeons, felt that this system had its inherent faults, such as the possibility of air or particulate emboli. 2 After modifying a Pall transfusion filter to filter out gross microemboli, the problem of air emboli as introduced via the syringe technique was still a possibility. Direct communications to: Jeffrey N. Kauffman, B.S., CCP, Emory University Hospital, Room 313-D, 1365 Clifton Road, NE, Atlanta, GA 30322 Submitted for publication February 1986. 36 The Journal of Extra-Corporeal Technology Eventually, we moved to a recirculating system using a double roller pump, pumping through an ice bath via a PVC coil. We were concerned, however, with the problem of massive air embolism being introduced by the perfusionist. We tried to limit this possibility by using collapsible bags (with all air evacuated) and a bubble trap (which offers minimal safety at best). After using several systems we determined three basic requirements for our system: 1. Due to the low temperatures of the solution (37 oq, a silastic tubing was thought necessary to achieve relatively high flow (200-400 ml/min) and high pressure (aortic root pressure of 80-95 torr). One quarter inch PVC tubing became stiff and collapsed at these temperatures and flows. However, some air emboli filtersb cracked due to particulate matter thought to be from silastic tubing (Personal communication from American Bentley). We have since employed Bentley Bypass 65 class VI 1!16" x 1/4" polyvinyl chloride tubingb with no filter leaks and still maintain adequate flows. 2. There was a marked difference (1-4 oq in efficiencies of cooling coils used. This was determined to be caused by surface area and heat exchange capabilities of PVC vs. aluminum or stainless steel. We settled on an aluminum coil (not compatible with blood). Ice baths also presented great variabilities in temperatures. The "magnetic stirrer"b concept proved to be the most efficient. (Graph 1) 3. A dual purpose filter (particulate and emboli) which had low priming volume and was easy to a Pall Biomedical Products Corp., East Hills, NY 11548 b American Bentley, Co., Irvine, CA 92714 Volume 20, Number 1, Spring 1988 131 12 l:r--6---lY __ ........ -6-----6--~----!::,