Clinical documentation

Administration of Blood Products Through Signature Edition^® Volumetric Pumps (Models 7100 and 7200)

Rodney A. Hasler, M.E.
Senior Clinical Study Specialist

SUMMARY

Studies have been performed by an independent laboratory to screen for potential pump-induced hemolysis with the Signature Edition^® Volumetric Pumps. These studies indicate no clinically significant hemolysis is induced by delivering blood products with an IVAC^® Signature Edition^® Volumetric Pump and Model 72980 Blood Administration Set or the Model 72023 Administration Set. Additionally, there did not appear to be any substantial adherence of platelets to the infusion set, nor was there significant release of cytosolic LDH due to membrane damage.

The practice of pump-assisted transfusion is still evolving. The convenience, improvement in flow rate control, and volume control afforded by infusion pumps make them an attractive alternative to pressure sleeve or gravity infusion of blood products.

When IV infusion pumps are used to infuse blood products, the concern most often expressed is whether passage through the pump mechanism contributes significantly to hemolysis of red blood cells. Many factors may affect hemolysis during transfusion (see Table 1). Because the influence of any combination of these factors may converge on a given transfusion event, it has been difficult for clinicians to establish guidelines which define acceptable cell damage. For example, FDA guidelines for the evaluation of shelf life require post-transfusion survival of red cells to be only 75% of the cells initially present when the unit was drawn.¹ In many instances the relationship between the amount of blood product infused and the resulting clinical response is not known. Of course the clinical condition of the patient will determine individual tolerance to infusion of red cell breakdown products.

TABLE 1
Factors effecting hemolysis during blood product transfusions

• Type of blood component
• Age of the blood product
• Viscosity
• Storage conditions (temperature, preservatives, container material)
• Handling (agitation, kneading to resuspend settled cells)
• External pressure applied to the blood bag
• In-line blood filters (pore size, filter material, degree to which clots occlude surface area)
• Interaction between blood components and fluid path surfaces or materials
• Type of mechanical infusion device, if any
• Infusion rate
• Needle or catheter gauge

There is a great deal of variation in transfusion practices among institutions. Infusion pumps do not completely automate transfusion, and are not intended to replace the nurse or other professionals in monitoring the process. For example, red cells tend to clump and settle in the blood bag prior to entering the tubing. The bag still must be mixed occasionally to resuspend the cells, as is common transfusion practice with or without pump-assisted administration.

Testing indicates that any concern about the contribution to hemolysis by the action of the Signature Edition Volumetric Pumps is not a practical concern. Stresses on cells forced through tubing diameter changes, filters and needle hubs would be similar whether flow was generated by a Signature Edition Volumetric Pump or under gravity flow.

METHODS

P.D. Mintz, M.D., Professor of Pathology and Internal Medicine and G. Anderson, SBB (ASCP), University of Virginia Health Sciences Center, performed studies in 1994 on the Model 7100 Signature Edition Volumetric Pump with the Model 72980 Blood Administration Set and the Model 72023 Administration Set.

Four units of red blood cells (adenine-saline added, AS1) and four pools of platelets per set were pumped in a laboratory setting. Testing was performed at or near the blood products' outdate. To detect any red cell damage, mean corpuscular volume (MCV) was measured on each sample and RBC histograms were printed. Cell-free supernatants were prepared by double centrifugation and were measured for free hemoglobin, lactose dehydrogenase (LDH), and potassium (K+). The hematocrit of each sample was determined in order to have some measure of the viscosity of the blood being pumped. Samples for each test run was collected under the five conditions in Table 2.

Pooled platelets were also tested by sampling at the five conditions listed in Table 2. Platelet concentration, mean platelet volume (MPV), and percent LDH release were used as markers for platelet loss and membrane disruption.

TABLE 2
Sampling conditions red blood cells and pooled platelets

• Directly from unit
• After passage through the filter and administration set by gravity alone (no pre-priming)
• After 20 ml of blood/platelets had been pumped at 999 ml/hr without a needle attached
• After 100 ml of blood (or 50 ml of platelets) had been pumped at 999 ml/hr with a 19g needle attached
• With needle attached as unit finished

RESULTS

None of the assays for red cell damage displayed clinically significant differences over their appropriate control. For the MCV, LDH, K+, and free hemoglobin, there were no significant differences by examination among sample means. There was one instance in which the LDH rose by 1000 U/L and the K+ rose 12 mmo/L from the unit control to the test conditions. Since both of these parameters were measured on the same instrument and the corresponding free hemoglobin did not increase, this isolated event is most likely a technical error in the testing (such as a dilution error). The platelet concentration, MPV and LDH release reflect no significant differences between the sample means by observation

CONCLUSION

Model 7100 and 7200 pumps have the same pumping mechanism, and therefore the same effect on blood hemolysis. Dr. Mintz and Mr. Anderson concluded that the Signature Edition^® Volumetric Pumps; when used with the Model 72980 Blood Administration Set or the Model 72023 Administration Set, did not induce any clinically significant hemolysis. Additionally, there did not appear to be any substantial adherence of platelets to the infusion set, nor was there significant release of cytosolic LDH due to membrane damage.²