Blood inventory management in the type and screen era

Previous models on the management of hospital blood inventories have mostly dealt with the optimization of variables related to the assigned, cross-matched inventory. Because the type and screen (T and S) procedure allows blood banks to manage surgical reserves with only unassigned inventories, it becomes necessary to gain insight into the factors that determine the efficiency of this kind of blood inventory.

Stochastic model that simulates the routine operation of a hospital blood bank inventory over a finite number of days was used. Factors that were analysed for their influence on outdate and shortage rates included the mean (MEAN) and variation (CVAR) in daily transfusion, the remaining shelf life of blood units shipped from the blood supplier (RSL) and the number of days between consecutive shipments (INT).

Outdate and shortage rates grew exponentially with CVAR, an effect that could be partially counterbalanced by increasing RSL. The variables, MEAN and INT, had little influence on the inventory, provided that blood stocks shipped from the supplier are targeted at the expected average demand for transfusion and RSL is greater than INT.

In hospitals that do not hold cross-matched inventories, CVAR is the major parameter in determining the blood inventory performance. Hospitals with large CVAR must be supplied with young red blood cell (RBC) units, whereas hospitals with smaller CVAR perform well with older stocks. These results advocate for using each hospital's CVAR as the leader parameter in regional optimization policies based on recycling blood units among participating hospitals.