Compatibility of packed erythrocytes and Ringer's lactate solution.

Packed erythrocytes are frequently reconstituted with crystalloid during rapid infusion. Dilution of whole blood with calcium containing solutions, such as Ringer's lactate has been cautioned against, citing possible clot formation because of chelation of the citrate anticoagulant. We studied the compatibility of Ringer's lactate solution and citrate phosphate dextrose (CPD)-preserved packed erythrocytes to evaluate the safety of using Ringer's lactate solution as a diluent in the emergency setting. Aliquots of CPD-preserved packed erythrocytes were diluted with either Ringer's lactate or normal saline solutions in ratios between 5:1 to 1:20 (packed erythrocyte to crystalloid), incubated at room temperature or 37 degrees centigrade and examined for clot formation at intervals up to two hours. Although clotting occurred at dilutions of 1:1 (packed erythrocytes to Ringer's lactate solution) and beyond, no clot formation occurred in the clinically relevant dilutions between 5:1 and 2:1. Thirty-two additional units of CPD-preserved packed erythrocytes were diluted to hematocrit values of 35, 45, 55 or 65 per cent and passed through a 170 micron filter. Flow rates of packed erythrocytes diluted with Ringer's lactate and normal saline solutions were compared. There was no difference in flow rates between packed erythrocytes diluted with Ringer's lactate compared with normal saline solutions. Ringer's lactate solution can be safely used as a packed erythrocyte diluent in patients requiring rapid blood transfusions.