Conclusions
This proof-of-concept study demonstrates the feasibility of washing stored RBCs using a simple, disposable system with efficiency comparable to that of conventional centrifugation, and thus represents a significant first step towards enabling low-cost washing of stored blood at bedside.
Methods
Stored RBCs were diluted to 10% haematocrit (Hct) with normal saline, matching the conventional washing procedure. The dilute RBC suspensions were passed through a column of coiled tubing to allow RBC sedimentation in normal gravity, thus separating them from the washing solution. Washed RBCs were collected using bifurcations located along the tubing. Washing efficiency was quantified by measuring Hct, morphology, deformability, free haemoglobin and total-free protein.
Results
The gravity-driven washing system operating at 0·5 ml/min produced washed RBCs with final Hct of 36·7 ± 3·4% (32·3-41·2%, n = 10) and waste Hct of 3·4 ± 0·7% (2·4-4·3%, n = 10), while removing 80% of free haemoglobin and 90% of total-free protein. Washing improved the ability of stored RBCs to perfuse an artificial microvascular network by 20%. The efficiency of washing performed using the gravity-driven system was not significantly different than that of conventional centrifugation. Conclusions: This proof-of-concept study demonstrates the feasibility of washing stored RBCs using a simple, disposable system with efficiency comparable to that of conventional centrifugation, and thus represents a significant first step towards enabling low-cost washing of stored blood at bedside.