Ringer's lactate solution has been shown to be an excellent initial intravenous fluid therapy for trauma resuscitation. Unfortunately, current guidelines mandate that only normal saline be administered with blood products because of the danger of creating emboli. In theory, the calcium in Ringer's lactate solution could overwhelm the chelating capacities of the citrate in stored blood, resulting in clot formation. These clots could be directly infused into the circulation, possibly under pressure in critically ill patients, and could lead to clinically significant emboli. Lorenzo and colleagues studied clot formation when blood products were administered with either normal saline, Ringer's lactate solution or Ringer's lactate solution with additional calcium chloride.

Twenty-five units of whole blood and 26 units of packed red blood cells were infused with one of five solutions: normal saline, standard Ringer's lactate solution or Ringer's lactate solution mixed with an additional 1, 2 or 5 g per L of calcium chloride. Using standard blood filter tubing, each mixture was infused at rates similar to those used in trauma resuscitation. Infusion time was noted, the appearance of gross clot in the filter was recorded, and the filter was weighed to determine the amount of clot formed.

In the whole-blood group, no differences were found in infusion times among any of the solutions. Filter weight did not differ between normal saline and standard Ringer's lactate but increased significantly with the solutions containing the additional 1 and 2 g per L of calcium chloride. In infusions with packed red blood cells, infusion times were significantly increased between normal saline and the highest calcium concentrations of Ringer's lactate. There was a trend toward increased filter weight as the calcium content increased, but this did not reach statistical significance. Some gross clot formation was observed in both whole blood and packed red blood cells with all solutions. The appearance of gross clot formation was significantly increased using Ringer's lactate with the highest concentration of calcium versus normal saline.

The authors conclude that Ringer's lactate containing the calcium concentrations in common usage does not cause increased coagulation when used in blood transfusion. In acute trauma situations, Ringer's lactate has proved to be an excellent initial intravenous fluid therapy because it is isotonic and has few side effects. Changing intravenous solution bags from Ringer's lactate to normal saline when blood is transfused can cause unwarranted delay and anxiety. The authors recommend amendments to standard blood bank recommendations to allow the use of Ringer's lactate with the transfusion of blood products at rapid infusion rates.