The Study Of Platelet Inventory Control Problem In Hospital

With the improvement of medical level and the popularity of component blood transfusion,the demand of platelet has increased over the past decades.Scientific and reasonable platelet inventory management has important economic and social significance,which can avoid unreasonable waste,improve the utilization of blood and relieve the pressure of blood supply to some extent.As an essential product of medical and health,besides the characteristic of short life cycle and highly uncertain demand,platelets also have features such as unreliable supply and heterogeneous demand(regular demand and emergency demand).Recent researches showed that the platelet freshness during transfusion would also have a certain effect on the health of patients.The random heterogeneity of demand,the uncertainty of supply,the high perishability of platelets and the effect of transfusion freshness on patient care increased the difficulty of the inventory control problem of platelets.Because platelet belongs to short cycle perishable products,it is necessary to consider the shelf life of platelets for platelets inventory management research,including ordering policy and issuing policy.The former determined the amount of fresh platelets replenished each time,while the latter determined the issuing order of inventory with different shelf life to meet different demand.This paper chose Markov Decision Process model to explore the optimal inventory management policy.Because the state space of this model is large and the common concave-convex property does not exist,it is impossible to discuss the structural characteristics of the optimal control policy.Therefore,this paper put forward a parametric heuristic policy,and used the method of combining the discrete event simulation and genetic algorithm to optimize the parameters of the heuristic control policy.The main works of this article were as follows:There are two main types of heterogeneous platelets demand in hospital.Regular demand refers to the platelets prepared for general surgery.General surgery can be postponed when supply is insufficient,and the demand can be backlogged.Emergency demand refers to the clinical massive hemorrhage and emergency treatment etc.The emergency demand cannot be backlogged when the supply is insufficient.High cost emergency blood collection or temporary allocation were needed to meet the demand,otherwise the patient may have life risk.This paper began with a simplified model of single-category demand,established Markov Decision Process model,explored the optimal ordering and issuing policy of platelets in hospital under regular demand and emergency demand separately,and summarized the main features of the optimal control policy under single-category demand.The parametric heuristic policy was designed as follows: The ordering policy was a threshold policy with a lower limit,and the issuing policy was a quota policy,that is,the freshest platelets of a fixed quota were reserved for future demand,and the remaining platelets issued from the freshest.The lower limit of order quantity ensured that the system has a certain amount of fresh inventory in any state to meet the uncertainty of future demand.The quota issuing policy ensured that the system could transfuse platelets as fresh as possible while responding to the uncertainty of future demand.The threshold and quota were optimized by genetic algorithm,and the numerical experiment results showed that the maximum deviation of parametric heuristic ordering and issuing policy with the optimal control policy was less than 2%.Based on the research of single-category demand,this paper studied hospital platelet inventory control under random heterogeneous demand,established Markov Decision Process model,and found that the optimal ordering and issuing policy were more complicated under random heterogeneous demand by solving the optimal control policy.The parametric heuristic policy based on the optimal policy was designed as follows: The ordering policy was a threshold policy with a lower limit,but when the soon-to-expire inventory was larger than a certain amount,the system needed to order an extra amount of platelets.The issuing policy was a combination of quota policy and reserve policy,that is,the freshest platelets with fixed quota were reserved for future demand and emergency demands on the day.The threshold and quota were optimized by genetic algorithm,and the numerical experiment results showed that the maximum deviation of parametric heuristic ordering and issuing policy with the optimal control policy was less than 1.5%.The majority researches of blood product inventory assumed that the blood supply was deterministic.However,in practice,due to the uncertainty of donor behavior and the uncertainty of blood test results,the supply of blood products usually cannot arrived on time according to the order quantity.Based on the random heterogeneous demand model,this paper studied the influence of uncertain supply on different threshold parameters and different policy performance.The experiment results showed that there was no significant change in the structure of the optimal issuing policy.The optimal ordering policy was more active when the actual replenishment quantity fluctuated down around the order quantity,and the ordering policy was steadier with the change of state when the actual replenishment quantity fluctuated up and down around the order quantity.