Using historical utilization and evidence‑based tools to set appropriate target inventory levels.
Why determining inventory matters
Effective inventory management is essential for balancing patient care, safety, and maintaining an adequate blood supply across Ontario hospitals.
This section provides tools to help facilities assess usage patterns and determine optimal inventory levels.
Key Principles of Inventory Management
| BALANCE | STEWARDSHIP | CONTINUOUS MONITORING | VALUE RESOURCE |
| Maintain inventory sufficient for daily/emergency needs while avoiding unnecessary stockpiling.1 | Avoid overstocking or stockpiling to reduce unnecessary discards due to outdating or waste. | Monitor inventory at regular intervals. Adjust inventory when hospital services or surgical volumes change.2 | Treat blood components as a valuable and limited resources. |
Quality Indicators for Monitoring Inventory Levels
- Rate of Outdating Components:
High outdating suggests overstocking, while low rates may indicate inadequate inventory if redistribution is not performed at your hospital. Review the provincial utilization graphs to compare outdate rates. Goal is to be meeting or below the provincial average. - Number of Urgent Requests
Frequent “STAT” requests to blood supplier may indicate insufficient inventory level. - Frequency of Redistribution of Components.
Excessive redistribution to maintain low outdate rate may indicate unnecessarily high inventory levels. Review the provincial utilization graphs graphs to compare outdate rates. Goal is to be meeting or below the provincial average.
Tools to Determine Appropriate Inventory Levels
Utilizing the Canadian Blood Services (CBS) portal3 to report monthly disposition of blood components and products helps hospitals recognize success and improvement in their blood utilization practices. One of the tools provided is the automatic calculation of average daily demand for components and a suggested days on hand estimation tool. In Ontario, it is highly encouraged for all hospitals to report their monthly disposition. For those sites that may not access this portal below are some ways to determine your inventory targets.
| Red Blood Cells (RBC) | |
|---|---|
| Weekly Usage | Track weekly RBC usage by ABO and Rh type over six months. Exclude the highest week and calculate the average for ideal stock[TC1] [LA2] . Ideal weekly inventory = # of units used/ (# of weeks tracked – 1) |
| Average Daily Red Cell Demand (ADRD) | Record daily usage by ABO and Rh type over one quarterCalculate the average daily red cell demand (ADRD) Average daily redcell demand = # of units used/90 days (4) Use 6 to 9 days on hand (DOH) [LA3] x ADRD as your optimal inventory, adjusting for distance to the blood supplier (e.g., 10-12 DOH x ADRD for more remote sites)If you are closer to blood supplier (<1hour) a 6 DOH x ADRD would be reasonable |
| Inventory Calculator | Tools like ORBCoN’s RBC calculator provide quick estimates based on annual transfusion numbers. Customize ABO proportions to reflect local patient population or use the Canadian distribution of blood groups5 to create your estimated inventory. The calculator will calculate 1-day up to 10-day inventory. Tips: Minimum inventory should support basic emergency patient care, typically at least 4 group O Rh-positive and 2 group O Rh-negative. Adjustments may depend on patient demographics, proximity to other hospitals, the frequency of transfusions, and delivery times from the blood supplier.If a 10-day inventory calculation yields fewer than 2 units, it is generally unnecessary to routinely stock that blood group and Rh type. It is best practice to order group and Rh specific RBCs on demand for patient use, when possible, rather than using non-group specific units. |
| Platelets (PLT) [LA4] | |
| Average Daily Platelet Demand | Not all hospitals need to stock platelets. Order as needed from the blood supplier. Hospitals with frequent or large trauma programs may choose to maintain on-site inventory to reduce delays and limit the need for frequent deliveries. |
| Inventory Calculator | Tools like ORBCoN’s PLT calculator provide quick estimates based on average daily usage. While PLT demand can vary daily, the tool uses annual usage data to provide a starting point or validate current inventory levels. Tips: In general, a 1 to 2 DOH is optimal.Standing orders may be offered by the blood supplier to help hospitals maintain inventory levels to maximize ordering and delivery efficiencies. |
Managing Inventory During Blood Shortages[KS5]
During shortages, hospitals should adjust inventory to maximize total blood inventory available provincially, for life-threatening cases. The Ontario Hospital Toolkit for Emergency Blood Management6 provides detailed guidance to determine appropriate target levels of inventory during the different phases of a blood shortage.
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Inventory Calculator for Red Cells
A tool for hospitals to use to perform a very quick estimate of what their ideal RBC inventory levels should be. By entering your annual number of RBC units transfused (for the most current year), an estimate of average daily use will be calculated by the formula locked in to the table.
By entering the disposition information reported into the CBS disposition portal for your hospital into this calculator, you can determine your green, amber and red phase inventory levels. If your hospital is able to report disposition to CBS by ABO/Rh, then ABO proportion calculation will be based on what is actually transfused at your site. If your site does not report by ABO/Rh then your ABO proportion will be calculated based on current Canadian population probabilities for ABO/Rh. -
Inventory Calculator for Platelets
This tool will serve as a broad estimate of the suggested levels if stock is held on site.
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Calculating Blood Inventory Levels
Calculating your Blood Component Inventory. How do you decide your ideal stock levels?
References:
- Chapman JF. Unlocking the essentials of effective blood inventory management. Transfusion 2007;47:190S-196S.
- Blood and Inventory Management Resources | National Blood Authority [Internet]. Blood.gov.au. 2024 [cited 2025 Jan 15]. Available from: https://www.blood.gov.au/blood-products/blood-product-management/blood-and-inventory-management-resources
- Canadian Blood Services Hospital Portal
- The National Plan for Management of Shortages of Labile Blood Components [Internet]. [cited 2025 Jan 21]. Available from: https://nacblood.ca/sites/default/files/2023-09/2023-09-26%20National%20Plan%20for%20Management%20of%20Shortages%20of%20Labile%20Blood%20Components.pdf
- How rare are blood types? [Internet]. www.blood.ca. Available from: https://www.blood.ca/en/stories/blood-types-canada-how-common-or-rare-are-they
- Ontario Contingency Plan for the Management of Blood Shortages Version 3 [Internet]. 2016 [cited 2025 Jan 21]. Available from: https://transfusionontario.org/wp-content/uploads/2020/06/2.1-Ontario-Plan-3_Plan_2016-12-21FINAL-REVISED.pdf