DAT and Selection of RBC Units for Transfusion

In 1984 effective with the 13th Edition AABB Standards, the requirements for performing a direct antiglobulin test and autocontrol for compatibility testing were eliminated.  The DAT is very important to detect delayed hemolytic transfusion reactions, certain autoimmune conditions, and drug-related hemolysis.

Since that time, the immediate-spin crossmatch and now the electronic computer paperless crossmatch may be used for most compatibility testing in place of the classic, antiglobulin-phase (indirect antiglobulin test) crossmatch.

If an antiglobulin phase (indirect antiglobulin test–IAT) crossmatch is performed, a donor unit with a positive DAT will cause a false-positive reaction.  Since most crossmatching does not include the IAT, it will not be affected by the DAT status of a donor unit.

Policy:

  1. Donor RBC units will NOT be routinely tested for DAT as part of component processing.
  2. The type of compatibility testing selected for a particular patient should be the technically simplest one (no need to do extra work unless so instructed by the transfusion medicine consultant/designate):
  3. Do a full antiglobulin-phase IAT crossmatch if ANY of the following applies:
    1. There are no two independent ABO/D typings on the patient during the current admission.
    2. The ABO/D type of the current admission does not match the historical information.
    3. The patient has a detectable antibody at 37C
    4. The patient has a history of a clinically significant antibody but no current antibody
    5. Whenever the consultant, transfusion medicine/designate requests it.
    6. Whenever the Medinfo HIIG record so indicates (in comment section)
  4. Do the immediate-spin crossmatch if ALL of the following apply:
    1. Only one determination of the ABO/D type
    2. The historical ABO/D type agrees with the current type.
    3. There are no antibodies reacting at 37C AND there is no history of antibodies at 37C.
  5. Use the computer/electronic crossmatch if ALL of the following apply:
    1. There are two determinations of the ABO/D type and they both agree with each other.
    2. The historical ABO/D type agrees with the current type.
    3. There are no antibodies reacting at 37C AND there is no history of antibodies at 37C.
  6. When to do a DAT on a donor unit:
    1. Patient antibody screen is negative but the full AHG crossmatch is incompatible.
    2. Part of a transfusion reaction workup where the AHG crossmatch of donor cells and patient serum is incompatible.
    3. Whenever the consultant, transfusion medicine/designate requests it.
  7. If a donor unit is found with a positive DAT, perform:
    • Do polyspecific and monospecific (IgG and C3) antisera
    • Perform an acid-elution.
    • Send the results to the transfusion medicine consultant/designate for review.
    • The reviewer will enter his review in the Medinfo HIIG in the Donor Consultation Section both as global donor comment and a result-specific comment against the antibody screen result.
    • Use of the DAT-positive donor unit:
      1. Select another RBC unit for the transfusion.
      1. The final decision to use the unit will be made by the Transfusion Medicine consultant/designate.

Important:  Don’t do a classic AHG/IAT phase crossmatch unless you have to do it  (see conditions above.)  A donor unit with a DAT is unlikely to be clinically significant and may be transfused safely to the patient in most situations.  Patients receiving electronic-crossmatch and immediate-spin crossmatch are receiving units with positive DAT without incident.

References:

  1. Standards for Blood Banks and Transfusion Services, Current Edition, AABB, Bethesda, MD, USA
  2. Guidelines to the Preparation, Use, and Quality Assurance of Blood Components, European Committee (Partial Agreement) on Blood Transfusion (CD-P-TS), Current Edition
  3. Technical Manual, Current Edition, AABB, Bethesda, MD, USA

Autologous Transfusion and Responsibilities

This is the process I developed for HMC Doha. The Medical Director (here Head, Transfusion Medicine HTM) is actively involved in the development of policies, processes, and procedures for ALL types of autologous donation in conjunction with the National Transfusion Committee NTC.

  1. Predeposit:  Directly under the control of the HTM for all aspects:  policies, procedures, and direct performance of the procedures, including annual review of criteria
  2. Perioperative:  HTM involved in conjunction with Surgery and Anesthesia through the NTC.
  3. Intraoperative:  HTM involved in conjunction with Surgery and Anesthesia through the NTC.
  4. Postoperative:  HTM involved in conjunction with Surgery and Anesthesia through the NTC.

Background:

There are four basic types of autologous transfusion:  preoperative, perioperative hemodilution, intraoperative, and postoperative drainage/collection.  The use of all of the above techniques can significantly decrease the need for homologous blood and as an added benefit reduce the risk of the disease transmission and immunosuppressive effects of such homologous transfusions.

Preoperative collection can make available packed red blood cells, whole blood, platelets, FFP, and/or cryoprecipitate.  However, at most two units of blood per week can be collected.  RBC’s can be stored for up to 42 days in the liquid state, frozen RBC’s up to ten years, platelets up to five days, and fresh frozen plasma and cryoprecipitate up to one year.  The last collection cannot be less than 72 hours prior to the surgery time.  Units can be collected as long as the patient’s hematocrit remains above 33%.  Supplemental iron and erythropoietin can increase the number of units harvested.  The biggest obstacle to using this service is the coordination of the patient scheduling for this procedure.  The blood bank does not have the resources to prospectively analyze the surgical scheduling and make the various appointments, contact the attending physician, etc.  Thus, this service is vastly underutilized.

PHD or Perioperative hemodilution (also called acute normovolemic hemodilution) is useful in cases when the anticipated blood loss is at least one liter and the initial hematocrit is at least 34%.  This includes essentially all types of surgery, but in particular cardiac, vascular, orthopedic, and urologic cases.  The patient’s hematocrit Hct. is lowered to the range of 20-25% and the blood is replaced by crystalloid in a ratio of 3:1–i.e. three times as much fluid as blood, or in the case of colloid replacement, a 1:1 ratio of colloid plus 0.5 to 1.0 ml. of crystalloid.  Crystalloid has the advantage of being readily removed by diuretic use.  However, this technique should not be undertaken when vascular access is inadequate or appropriate monitoring devices are lacking.  The physician performing PHD must be familiar with the compensatory mechanisms normally invoked when the hemoglobin is acutely lowered.

Another new twist to PHD is the perioperative collection of platelets by a special attachment to a cell-saving machine.  This could allow collection of a typical apheresis load, about 6 to 10 units of fresh platelets for potential use.  There are currently studies underway to determine if this has particular clinical advantages to warrant the additional cost.

Intraoperative salvage may be performed with a number of canister or automated devices.  The latter is usually used when there are large volumes (usually 3 or more units) of blood to be salvaged.  Depending on the body site, the recovered material is at least filtered and may or may not be washed.  Care must be taken to collect the blood at a low suction rate and with minimal turbulence to minimize hemolysis.

Postoperative drainage collection of certain sites such as post-knee replacement surgery or chest wounds involves a canister collection device.  This blood may or may not be filtered before reinfusion.

Note that perioperative and intraoperative material can only be transfused up to six or eight hours at room temperature or 24 hours if refrigerated at 1-6 degrees (depending on the method used) post collection to minimize the risk of infection.  Intraoperative collection is usually contraindicated in cases of cancer and if the bowel has been violated.

Other Issues:

The transfusion criteria for autologous blood is the same as for allogeneic units. If you wouldn’t transfuse if no autologous blood were available, you shouldn’t transfuse because you have it!

The same compatibility testing algorithm applies both the autologous and allogeneic units.

Policy:

  1. Scope:
    1. Predeposit collection of Whole Blood/RBCs and plasma is under the authority of Transfusion Medicine.
    2. Perioperative hemodilution, intraoperative cell salvage, and postoperative drainage collection is under the authority of the National Transfusion Committee in conjunction with the Departments of Surgery and Anesthesia.
      1. Head, Transfusion Medicine will liaise with the clinical departments as needed.
      2. Transfusion Medicine may provide blood bags for perioperative hemodilution upon request.
    3. Transfusion Medicine does not receive autologous collections—perioperative, intraoperative, or postoperative drainage collection.
  2. Processes directly under Transfusion Medicine authority:
    1. Autologous collection of whole blood/RBCs (predeposit) for elective surgeries will be considered especially if the patient has a dangerous antibody for which antigen-matched units cannot be easily obtained (e.g. anti-k (cellano), anti-PP1Pk (anti-Tja), anti-H (Bombay and Para-Bombay phenotypes).
    2. Autologous collection of plasma may be considered for patients with IgA deficiency with documented specific anti-IgA antibodies.
    3. Autologous collection of platelets may be considered for patients with anti-platelet antibodies and platelet refractoriness.
    4. Other requests will be reviewed by the Head, Transfusion Medicine or designate.
    5. The final decision to proceed with items 2.1 and 2.2 will be made by the Head, Transfusion Medicine or his designate.
  3. Process for Transfusion Medicine Autologous Procedures
    1. The requesting physician shall provide a written order to the Blood Donor Center.
    2. The request will be reviewed by a transfusion medicine physician.
    3. If rejected, the requesting physician will be notified with the reason for the rejection.
    4. If approved, the donor shall be screened by the usual donation process except:
      1. Hgb >= 11 g/dl will be acceptable for whole blood collection.
      2. Females may also donate autologous plasma.
      3. The last autologous donation will be at least 72 hours before the elective procedure.
    5. Marker testing:  Components from autologous donors with confirmed positive cases of HBV, HCV, HIV, syphilis, malaria, or HTLV infection will NOT be used for autologous donation and will be destroyed.
    6. Computer:  Autologous collections will be entered as specifically as such in the Medinfo  Hematos IIG blood bank computer system and be labeled as autologous in their corresponding ISBT labels.
    7. Crossover of autologous units requires review and approval by a transfusion medicine physician–only those cases where the donor met the standard donor criteria will be considered.
    8. The transfusion criteria for autologous units shall be the same as for homologous blood.
    9. Both autologous and allogeneic units will follow the same compatibility testing algorithm.

References:

  1. Standards for Blood Banks and Transfusion Services, 29th Edition, AABB, Bethesda, MD, USA, 2014
  2. TRM.41600 CAP Checklist Standard, 2015

Processes and Software Building 11: Middleware and Truth Tables

I try never to forget that in most cases, the simplest solution is the best.  This applies to software as well.  The ideal situation is to have one interface to the blood bank software.

In many laboratory softwares, there is a middleware to interpret the raw data as it comes out of the equipment which may reformat it and interpret it.  This approach means that you have to have one interface then middleware and then finally the software.

Inevitably, both the middleware and the laboratory software will need updating.  Can you assume that they will still work after either or both are updated?  Will there be regression errors?

A good example of regression errors is the Microsoft Windows Feature Update (sometimes referred to as the Update from Hell!).  Previously working functionality gets broken, data can be lost, etc.

In Medinfo, you store a truth table of possible results and interpretations.  Medinfo will directly read the machine interface data, interpret it according to the rules you make.  The data can be numeric or alphanumeric or both.  Each test, each equipment can have its own unique rules if necessary.

In my opinion, it is best to avoid middleware if your blood bank software can perform this function directly.  When you upgrade it, it is much less likely to show errors—and you only have to deal with one vendor.  Can you be certain that the middleware vendor and the blood bank software vendor will work well together to resolve any issues?

The following are some examples of truth tables, i.e. the rules for interpretation and disposition of interface results actually used at HMC Doha during my tenure there:

Example 1:  Blood Component Production Truth Table

Production can only proceed if the volumes are within the specified ranges.  This is very important if you are going to perform pathogen-inactivation since the ultraviolet illuminator requires a specific range, even more so if you are adding Mirasol (riboflavin) and PAS (platelet additive solution).


Example 2: ABO/D Antigen Typing:

One manufacturer’s requirements:

Example 3:  Complicated D Typing Algorithm:

The acceptable range for automatic interpretation is much more complicated for D typing with the Ortho Vision MAX and uses 3 different monoclonal cocktails:

Example 4:  Direct Antiglobulin Test Algorithm:

Both alphanumeric and numeric results are used.

Example 5:  Four-Cell Antibody Screen:

Truth table for interpretation requires both alphanumeric and numeric results:


Conclusion:

If you are fortunate to have a dedicated blood bank software, you may not need middleware.  Otherwise, you may need to use it for linking to general laboratory systems.  Hopefully, your vendors will cooperate with each other.

To Be Continued:

2/7/20

Processes and Software Building 9: Enforcing GMP

Enforcing Good Manufacturing Process Through A Dedicated Blood Bank Software

Blood components are a drug and like medications must be consistently produced and follow Good Manufacturing Practices GMP.  The following system that I set up for HMC Doha Qatar blood collection and processing is an example of the impact of Medinfo donor software on enhancing our safety and GMP compliance.  In earlier posts, I provided the Medinfo flowcharts for these processes.

This is an outline of the processes I built in conjunction with the Medinfo software engineers:

  1. Registration:
    1. Read the barcode on the specified picture ID (usually a Qatar Residency/Citizen card).
      1. Retrieve the prospective donor’s demographics in English and Arabic from the Ministry of Interior.
      2. Check the donor deferral database (Qatar has only one), defer if contraindicated according to the rules built into Medinfo.
    2. Choose the type of donation (apheresis or whole blood;  volunteer, directed, or autologous).
    3. Print a consent form and ISBT specimen labels for the donation.
  2. Pre-Collection Screening:
    1. Perform the donor questionnaire on-line in English or Arabic:  this has contingent fields and could exceed 60 questions depending on the answers provided.
    2. Proceed to donor physical exam (vital signs and arm check).
  3. Collection:
    1. Collect the whole blood or apheresis component and specimen tubes:  determine if the collection meets the volume requirement and time limit.
    2. Send the specimens for donor marker and donor immunohematology testing.
    3. Send the raw components for processing.
  4. Donor Marker Testing:
    1. Perform NAT, EIA, and LIA marker testing according to algorithms defined in Medinfo.
    2. Perform follow-up reflex marker testing according to Medinfo criteria.
  5. Component Processing:
    1. Process the raw whole blood in the Reveos machine into PRBCs, leukodepleted plasma, and buffy coat platelets.
    2. Filter/leukodeplete the RBCs.
    3. If marker test results pass:
      1. Pool the buffy coat platelets according to the platelet yield index for a yield of 2.4E11/dose.
      2. Add platelet additive solution PAS and pathogen inactivate (Mirasol).
      3. Pathogen inactivate the whole-blood-derived plasma.
      4. Divide the apheresis plasma into 200-250 ml aliquots and pathogen inactivate.
    4. Divide the apheresis platelets to provide a yield of 2.4E11 in each dose, then pathogen-inactivate (PAS had been added at the time of the apheresis collection).
  6. Donor Immunohematology Testing:
    1. Perform ABO/D testing and antibody screen (identification if positive):
    2. If antibody screening positive, discard the component.
      1. If ABO discrepancy, send for manual review and approval, otherwise discard.
  7. Labelling, Storage, and Transfer:
    1. If all criteria were met, attach the final ISBT label (this can only be printed based on the acceptance of each component).
    2. Place the components into storage (37C, 1-6C, or <= minus 18C).
    3. Distribute to the hospital blood banks using Inter-Depot Transfer function.

I emphasize that only if all criteria across all areas pass is the final ISBT label printed.  Medinfo is not a label printing program.  It enforces the rules ruthlessly.  My technical staff tell me that it is merciless—as it should be for patient safety.

Attachments:  None—please refer to earlier posts regarding collection, processing, donor testing, and inter-depot transfer.

28/6/20

Processes and Software Building 8: Reveos and Mirasol

Automated Component Processing:  Reveos and Mirasol Pathogen-Inactivation

The production instruments have more complicated interfaces than the testing equipment discussed in the previous post:

In the collection area (on-site or remote), the cvolume of the whole blood and collection time are recorded in Medinfo and based on the rules, production may only occur within specified volume and collection time.  Otherwise, Medinfo will block further processing.

The ISBT unit number of the whole blood units are read by the Reveos.  Only those units passing the collection criteria will proceed to separation.

In about 20 minutes, the Reveos machine will simultaneously process four units of whole blood into packed RBCs, leukodepleted plasma, buffy coat platelets, and residual buffy coat.  The volumes of the RBCs, plasma, and platelets are recorded in Reveos.  For the platelets, the platelet yield index is also provided.

Within Medinfo, these parameters are compared to criteria of acceptability according to the manufacturer.  Volumes for the platelets and plasma must be within certain ranges to permit pooling and pathogen inactivation and additive solution.  Medinfo will not permit these subsequent procedures if the values are out of range and the intermediate components will be discarded.

Here is a sample of Reveos acceptable ranges for component volumes:

E4207 – Whole Blood CPD 450 mL

Volume Consequences

< 400 mL Discard

400 – 500 mL OK

> 500 mL Discard

E5259 – Leukodepleted Packed Red Blood Cells

Volume Consequences

< 230 mL Discard

230 – 330 mL OK

> 330 mL Discard

E2807 – Platelets Concentrate 20-24°C

Volume Consequences

< 20 mL Discard

20 – 55 mL OK

> 55 mL Manual decision

E2555 – FP24:  Plasma Frozen <= 24h

Volume Consequences

< 170 mL Discard

170 – 360 mL OK

> 360 mL Manual decision

All these production parameters are permanently stored in Medinfo as part of the production record of that unit.  The actual location (bucket) of the whole blood unit in the Reveos is also available.

RBCs are manually leukodepleted and the final volumes recorded in Medinfo based on weight.  Based on the platelet yield index, platelets are pooled and the final volume recorded.   Those permissible volumes are next treated with platelet additive solution PAS and then pathogen inactivated.  The acceptable volumes are based on the process used, e.g. platelets in plasma versus platelets in PAS.

How a sophisticated blood bank software like Medinfo enforces good manufacturing process at all stage of production will be a future topic.

To Be Continued:

26/6/20

Processes and Software Building 7: Interfaces 2

Blood Bank instruments may perform tests and release test results in a numerical or alphanumeric format or both.  For example, nucleic acid and enzyme immunoassay may release a qualitative result (e.g. positive, reactive, borderline/grayzone, negative, nonreactive).  Alternatively, the machine may release the signal to cutoff ratio (S/CO) as a numeric result.

Blood bank software may use either kind of result on which to base interpretative rules for acceptability of the donor.  The qualitative result criteria are based on the quantitative SC/O but the equipment automatically interprets this.  The S/CO ratio of 1 is the cut-off point.  Thus a value of 0.99 is negative and the value 1.01 is positive.  But is it really so clear-cut since the difference between the two is so small?  Thus, some people have added the term grayzone for values close to but below the cutoff.  Could a value of 0.95 be an early infection?

I personally prefer to see the actual cutoff but use the manufacturer’s criteria for interpretation.  As a physician, it is good to review the S/CO on serial exams.  If a borderline or grayzone result becomes positive, then perhaps the original result indicated early infection.  The question still remains, what is the grayzone?  0.95 to 0.99, 0.90 to 0.99, etc.  Some accrediting schema have not used grayzone for interpretation.

With Medinfo’s blood bank software, I could chose either option or both—or at least store the S/CO as a nonreported result for subsequent review.  I could even chose, test by test, in a series between reporting either S/CO or the qualitative result.

Semiquantitative results, e.g. in {0, 1+, 2+, 3+, 4+} are qualitative and could also include mixed field (mf) and hemolyzed (h).  I showed examples of this with ABO/D antigen typing in a previous post—see attachment.

On the contrary, the results from blood production equipment may include parameters such as time of preparation, original volume, final volumes for each component, platelet yield index as an indirect measure of platelet count.  When there is pooling, the final total volume is critical to determine if pathogen-inactivation procedures and platelet additive solution can be used.  This is a much more complicated interface.

The blood production equipment interface issues will be considered in a future post.

Attachment:

ABO/D sample typing process in Medinfo

To Be Continued:

24/6/20

Inter-Depot Transfer: Further Thoughts

In my recent post, I provided sample flows and parameter mapping for delivery of blood components.  The final components from the component preparation center may be sent to various depots (freestanding location and/or hospital blood banks.  There should be complete traceability for every step (from donor reception, collection, testing, and processing) transport between locations, and finally the exact storage site, which might include which refrigerator/freezer/incubator and even shelf/position number for each component is stored.  The end of that document showed rules for type/antigen matching.

For disaster planning, rapid inventory enumeration by type is very important.  This can be very time-consuming manually.  With our Hematos blood bank system, we could quickly get total inventory across the Qatar or by hospital in less than one minute.  We could also quickly find antigen-matched units across the system and reserve it at any one site for another if necessary.

Smart blood bank dispensing refrigerators, as offered by Haemonetics and Angelatoni, may also serve as depots and take the place of a hospital blood bank for some dispensing.  These solutions can also capture vital information about the storage conditions of the components and prevent release if the storage criteria are not met.  They can also interface with blood bank computer systems and use the main system’s logic for the dispensation rules.

Upon receipt at the hospitals from the blood processing center, the forward ABO and D typing must be confirmed.  We used D reagents which detected partial D so that we would call such donor units as D-positive.  However, if a patient type reagent insensitive to partial D types were used, it is possible for a unit to be typed as D-negative whereas in the donor center it might be D-positive.  Sometimes, nothing types consistently as D-positive:  all you can say is that with a particular reagent and lot number, there is or isn’t reactivity.

The greatest complexity is for RBCs since potentially so many antigens exist.  Criteria for matching/ignoring certain antigens must be made.  Critically significant antibodies such as the Kell, Duffy, Kidd, and certain Rh (D and c) must be antigen matched.  A robust blood bank computer system can enforce these rules.

For other components, antigen/typing may be less important.  In fact, in most situations, any type of platelets can be given to anyone (except neonates).  Despite the potentially incompatible plasma, there is rarely significant hemolysis.  In fact, if pooling platelets without regard to blood types is done, a platelet transfusion is a common cause of a positive direct antiglobulin test DAT—something that is not clinically significant.  No one died of a positive DAT by itself for this reason.

Specific rules for compatible plasma types are important, but nowadays, low-titer group A plasma may be used like universal AB plasma.  The challenge is to be able to perform the ABO titration (specifically anti-B) quickly—titration can be a slow process, even with automated equipment.  A similar situation for low-titer, universal group O whole blood requires both anti-A and anti-B titration (I will return to this topic in a future post).

Overview: Inter-Depot Transfer and Allocation of Blood Components

While I was working in Qatar, this was the overall process for transfer and allocation of blood components. Once they were finally labelled (only possible if all criteria had been meet), they were transferred from the Blood Donor Center BDC to Hamad General Hospital Blood Bank, from which they were distributed to all hospital blood banks in Qatar. Similarly, units could be transferred between the various hospital blood banks.

One could track components as being in:

  1. BDC
  2. Transit BDC to HGHBB
  3. HGHBB inventory
  4. Transit HGHBB to another hospital blood bank
  5. Transit between any two hospital blood banks

An inventory manifest would be printed to show all transferred units.

For patient use, allocation rules applied which would determine if an electronic or a full antiglobulin-phase crossmatch could be used and whether specific antigen-matched components were required.

There were also separate rules for emergency release if the standard criteria could not be met.

Active Inventory Management: Further Discussion

Yesterday’s post showed my active blood inventory management scheme for my previous position in Qatar.  I thought today I would elaborate on how I adjust the inventory based on critical shortages and planning for disasters and other major events.

I always review the critical shortages to check for atypical usage (e.g. a disaster situation) or production issues (equipment breakdown, shortage of donors during holiday period).

If it is due to increased utilization, I try to adjust the critical and desirable inventories upward to cover the shortfall for future events.  However, it is not always possible if the event is a one-of-a-kind situation unlikely to recur.  Also, I must take into account the available resources (supplies, kits, manpower, equipment) to see if I can cope with the increase.

If it is due to resource issues, I see if I can bolster those by recommending increases or improving utilization of what is available.

Very important is through-put:  How quickly can I produce components from whole blood or apheresis components?  This was one of the major reasons we shifted away from PCR to other NAT testing with single-well processes since to minimize the need to make additional runs (Grifols Panther System).  Also, automated component processing can greatly speed production (one Reveos can process four whole blood units in about 23 minutes or about 12 units in 75 minutes.)  Those staff can be busy with other tasks while the machines are working.

In the system I developed in Qatar, we could complete processing into components (RBCs, buffy coat platelet pools, leukodepleted plasma)–Reveos 3C Program, all marker and immunohematology testing, leukoreduction of the pools and RBCs, Mirasol pathogen inactivation, and platelet additive solution in as little as five hours!!  There is great need for speed in a place that must be 100% self-sufficient in all blood components. We could even further reduce the total processing time if we only made RBCs and plasma, Reveos 2C Program

In rapid turn-around events, it is most helpful to have a robust blood bank computer system that can scale to the challenge.  Also, it must mercilessly enforce all the rules starting with donor qualification, screening, collection through testing and production.  At times of emergency, it is difficult to meet Good Manufacturing Processes manually.

After each major shortage, I recommend a “post-mortem” analysis of the situation with senior donor and quality staff to analyze our processes and see if we can further optimize them for the future.  A report is prepared and reviewed by me as the Division Head/Medical Director of the Blood Bank.  If possible, we implement our recommendations.  If not, I request additional resources from the Administration.

As regards Disaster Planning, I always asked Administration how many victims did they want to save?  When I got the response, I always try to adjust inventory by two extra RBCs and one adult platelet dose (> 2E11) per salvageable victim.  This may come at the expense of increased wastage, especially in a region that cannot export the excess, unused stock.

The exasperating issue is that I didn’t get a clear answer on this last point.  What number should I use?  I made a spreadsheet showing calculations for a variety of endpoints, e.g. 100, 500, 1000 treatable victims and sent this to Administration to consider.