A TECHNIQUE FOR RETROGRADE AUTOLOGOUS PRIMING

The following is a description of a retrograde autologous priming (RAP) technique. Our prime consists of 2,000cc isolyte solution, and 12.5g mannitol, 50mg benadryl, and 20mg famotidine. The prime drugs are not mixed with the prime because the total prime is reduced to about 500cc after the RAP is completed. The RAP process is initiated just before the bypass is commenced. This is done in order to minimize the potential drawbacks of RAP, such as lowered cardiac output, and hemodynamic instability. The aortic side could be thought of as "afterload" and the venous side is "preload". The preload is the most important factor in cardiac output, so the drainage via the right side of the heart is done at the last minute when the bypass could be easily initiated in an emergency. The RAP is performed in close collaboration with the anesthesiologist in order to keep the patient hemodynamically stable.

Step 1. All the cannulas, including the retrograde cardioplegia cannula, are inserted and connected to the heart lung machine. The aortic line is drained first, the clamp is applied at position A, and Clamp C is removed thus allowing the blood to flow retrograde from the aortic cannula towards the filter. We use a venous bag in place of a hardshell reservoir, and we have a purge line going from the top of the filter to the venous bag with a 3 way stopcock in the middle of it. The purge line is disconnected from the stopcock and the fluid is drained from the aortic canula, retrograde into the aortic line and up the filter to the purge line. The fluid is directed through the purge line into a container on the floor. Once the blood in the arterial line reaches the filter the aortic part of the drainage is done and the venous side of the drainage is initiated. The clamp is reapplied at point C, and clamp A is removed.

Step 2. The sample port on the venous side is disconnected and the blood is slowly drained into a container on the floor. Once, the blood reaches the sample port the sample port is connected back to the venous line. The clamp at position B is slowly released to allow the venous reservoir to fill with blood. The blood pump is kept in a slow recirculation mode. At the same time the purge line at the top of the filter is used to remove the fluid into a container. Once the blood reaches the top of the filter the clamp B is applied to the venous line and the fluid is discarded.