RAPID TRANSFUSION OF PACKED RED-BLOOD-CELLS - EFFECTS OF DILUTION, PRESSURE, AND CATHETER SIZE

Study objective: To examine flow rates and quantify red blood cell (RBC) destruction using various catheter sizes, pressures, and dilutions in the transfusion of packed RBCs. Design: Study equipment was identical to that used in clinical practice. Laboratory tests consisting of plasma free hemoglobin, hematocrit, RBC count, and plasma potassium were used to assess RBC destruction. Statistical analysis was performed using the two-tailed Student's t-test. Statistical significance was considered to be .05. Intervention: Packed RBCs were transfused in vitro through 16-, 18-, 20-, and 22-gauge catheters using no pressure, 150 mm Hg, and 300 mm Hg pressure as well as dilutions of 0, 100, and 250 mL normal saline. Outcome measures: Flow rates in milliliters per minute were recorded for all combinations. The extent of RBC destruction was estimated using RBC count, hematocrit, plasma free hemoglobin, and serum potassium. Results: Increases in flow rates of tenfold simply by diluting the units with 250 mL normal saline and sevenfold with the application of a pressure device were seen at all catheter sizes. The combination of both dilution and pressure increased flow rates 33-fold, varying between 70 and 300 mL/min for 22- and 16-gauge catheters, respectively. No significant difference in RBC destruction was seen among the four catheter sizes. Conclusion: Flow rates of packed RBCs sufficient for volume resuscitation can be achieved using 20- and 22-gauge catheters without evidence of increased RBC destruction. When it is impossible to obtain large-bore venous access or when such access would necessitate a delay of five to ten minutes, smaller catheters used in conjunction with dilution, pressure, or both should be considered.