Washed red cells: theory and practice

Abstract

Washing of red cells is sometimes performed to reduce allergic reactions due to contaminating plasma proteins or to reduce the concentration of potassium accumulating in the supernatant of red cells during storage as an alternative to transfusion of fresher red cells in patients at risk of hyperkalaemia. There are a variety of methods for washing red cells, and the laboratory data suggest that variables such as age of red cell before washing, washing method and solution, storage medium and length of storage time after washing can all effect the final red cell quality. Studies suggest that washing removes 90-95% plasma, but the proportion of units below 0Á05 mg/dl IgA (equivalent to IgA deficient) is variable dependent upon methods used. Although potassium levels are reduced immediately following washing, the rate of leakage following subsequent storage is method-dependent, requiring careful consideration of shelf life if potassium reduction is the goal. Other markers of red cell quality such as haemolysis are negatively impacted by washing so a reduced shelf life compared to standard red cells is appropriate, especially following irradiation. Data from animal models and clinical studies on possible additional benefits of washing, such as reduced lung or kidney injury, are mixed, ranging from some benefit to some harm, and further studies are warranted.

Familial pseudohyperkalemia induces significantly higher levels of extracellular potassium in early storage of red cell concentrates without affecting other standard measures of quality: A case control and allele frequency study

“…We do not yet know whether other manufacturing processes may perturb the potassium homeostasis of FP RCC. For example, the removal of potassium‐rich supernatant in FP units may disrupt the equilibrium cation gradient across the FP RBC membrane and cause further potassium loss, destabilizing the RBC; that is, when WB donations are refrigerated prior to manufacture into RCC, or during “washing” of RCC, warranted for recipients allergic to plasma proteins 35 . Moreover, irradiation of RBC, a routine practice for specific patient recipient groups, is known to increase the rate of potassium leakage.…”

Effect of washed versus unwashed red blood cells on transfusion‐related immune responses in preterm newborns

“… 14 It would appear from the current data that the beneficial effect of PRBC washing is also evident in the extremely preterm newborn. Washing may, however, result in post‐washing increases in potassium and haemolysis, 29 and as a result, washed PRBCs have a reduced shelf life of 28 days compared with that of 35 for standard unwashed leucodepleted PRBCs. In addition, while animal data report conflicting effects on survival and end‐organ injury, 30 , 31 a recent review concludes that it is unclear how these data relate to humans.…”

“…In addition, while animal data report conflicting effects on survival and end‐organ injury, 30 , 31 a recent review concludes that it is unclear how these data relate to humans. 29 …”

“…In addition, while animal data report conflicting effects on survival and end-organ injury, 30,31 a recent review concludes that it is unclear how these data relate to humans. 29 While a 'two-insult' hypothesis has been proposed to underlie TRIM with long-term or permanent alteration to immune function compounded by repeat transfusion exposure, 32 the exact mechanism remains poorly understood.…”

The Effects of Free Heme on Functional and Molecular Changes During Ex Vivo Normothermic Machine Perfusion of Human Kidneys

“…Although pRBCs can be stored for up to 42 days, over time their condition deteriorates ( 7 ). During storage the destruction of the RBC membrane causes the release of haemoglobin and free heme ( 8 , 9 ). This is further exacerbated during NMP when RBCs come into contact with artificial surfaces and by the perfusion pump ( 10 , 11 ).…”