Platelet Refractoriness: Platelet Cross-Matching Requests

Transcription

1 Platelet Refractriness: Platelet Crss-Matching Requests Platelet Transfusin Guidelines: Platelet prducts are generally in shrt supply in the UCSF hspital bld bank and at Bld Centers f the Pacific (BCP), the bld supplier fr UCSF. T help guide prviders in mre apprpriate use f these valuable resurces, the hspital Transfusin Cmmittee, clinical services cmmnly using platelets, and the Transfusin Service have set sme useful guidelines fr platelet transfusin. These guidelines can be fund n the transfusin service website in the UCSF nline Lab Manual: Evaluatin f a Patient with Platelet Refractriness: Crssmatched platelets are frequently requested fr patients wh seem t be refractry t platelet transfusin. It is imprtant t nte that it is much mre cmmn t have a nn-immune cause fr an inadequate pst-transfusin increment, as ppsed t an immune cause. Cmmn scenaris that may suggest a patient is all-immunized while in fact they are nt include: 1. The pst-cunt was drawn many hurs after the platelet transfusin. Patient may have had an apprpriate platelet increment in the immediate pst-transfusin perid and subsequently the cunt decreased gradually ver time. 2. The pre-cunt was drawn many hurs befre the platelet transfusin. Patient may have had a much lwer immediate pre-transfusin platelet cunt in viv, and therefre the increment bserved wuld have been apprpriate fr that pre-cunt, while it appeared inadequate based n the platelet cunt dne much earlier. 3. The platelet dse given was nt large enugh t increase the cunt sufficiently. An example wuld be: a. Number f platelets in the unit was n the lwer acceptable range (~3.0 x per unit), and the patients had a high BSA (bdy surface area). 4. The patient is cnsuming platelets (but is NOT all-immunized): a. Fever b. Sepsis c. Mucsitis d. Occult r bvius bleeding e. DIC f. Splenmegaly (sequestratin f platelets) g. GvHD h. Hematpietic Stem Cell Transplantatin i. Hepatic ven-cclusive disease (VOD) 1 March 2014

2 j. Medicatins such as Amphtericin k. Drug-Induced Thrmbcytpenia (DIT) l. Platelet autantibdies (ITP, Pst-Transfusin Purpura) In rder t determine whether r nt yur patient may be all-immunized t platelet prducts it is necessary t perfrm multiple 10 min-1 hur pst transfusin cunts (bld sample drawn between 10 min-1 hur after end f platelet transfusin). Crrected Cunt Increment (CCI) Calculatin: When a request fr crss-matched platelets is received by the bld bank, the lab medicine resident uses the 10 min-1 hur pst cunt values t calculate multiple crrected cunt increments (CCIs) t help decide whether r nt a patient wuld benefit frm crss matched platelets. CCI = [pst cunt-pre cunt] x BSA (m2) x 1011 # f platelets transfused Bld bank uses the exact number f platelets in the specific unit transfused t the patient fr accurate CCI calculatin, but when this number is nt available the minimum acceptable number f platelets in each apheresis unit (3.0 x ) may be used instead. If the CCI is < 7.5 n at least tw ccasins, platelet crssmatching may be indicated. An nline tl is als available at: This tl uses 3.0 x as the estimated number f platelets transfused per each apheresis unit. (Nte: make sure yu check the Pheresis bx instead f Randm dnr ) Example: Pre-transfusin platelet cunt: 3,000/ L 1 hur pst-transfusin platelet cunt= 21,000/ L BSA=1.85 m 2 1 apheresis unit was transfused ~3.0 x platelets [21-3] x 1.85 x CCI = 3 x = 11.1 Hw is a Platelet Crssmatch Test Perfrmed? Yur patient s plasma is tested against a panel f platelets frm the mst recent platelet dnrs at BCP (usually thse units that were dnated the day befre and/r n the same day as crss-match testing). The test methd currently used is a slid phase red cell adherence assay (Capture-P, Immucr). Mre infrmatin n this test 2 March 2014

3 can be fund here: Brchure_US_Web.pdf Hw are the Results f Platelet Crssmatches Reprted? The first time the Bld Bank Resident is cnsulted t evaluate a new patient suspected f being platelet refractry, they will enter a cnsult nte in APeX, including a brief assessment f patient and results f the initial crss-match r HLA testing. The results are reprted as the number f units that are reactive ut f the ttal tested. - Units that are REACTIVE against patient plasma are INCOMPATIBLE. - Units that did NOT shw reactivity are cnsidered COMPATIBLE. Fr example: Platelet crss-match results shw reactivity in 20 ut f 30 units tested means nly ne third f dnrs tested were fund t be cmpatible. At this time, results f all subsequent platelet crssmatch tests will als be entered in APeX as a cnsult nte by the Bld Bank Resident. Interpretatin f the Platelet Crssmatch Results: - If 100% f the dnr platelet units tested are cmpatible, yur patient is NOT ALLOIMMUNIZED and has sme ther reasn fr inapprpriate respnse t platelet transfusins (fr example, nn-immune mediated causes). Crssmatch cmpatible units are NOT indicated in such cases. - If 100% f the dnr platelet units tested are reactive (incmpatible), this mst likely suggests a significant degree f allimmunizatin t HLA antigens, althugh in rare instances platelet-specific allantibdies r autantibdies (the latter seen in ITP) may be the reasn fr such significant reactivity. In such instances bld bank will recmmend a repeat crss-matching against a new set f platelet dnrs, and als may cnsider HLA Class I typing/ anti-hla Class I antibdy testing in case there is a need fr HLA-matched platelet units. - Mst platelet crss-matching results fall smewhere in the middle f these tw extremes, suggesting mild, mderate r significant degree f allimmunizatin. - Crss-matched platelets are nly helpful fr platelet refractriness due t allimmunizatin (either t HLA antigens, r rarely t platelet specific antigens). - Crss-matched platelets d nt prevent transfusin reactins. - In patients wh have a cmbinatin f immune and nn-immune causes fr platelet refractriness there is n guarantee that the crss-matched platelets will be superir t randm dnr units. 3 March 2014

4 - Crss-matching is nt indicated fr patients with platelet-specific autantibdies (ITP patients) as it is expected these patients destry bth self and nn-self platelets equally. Ordering Crss-matched Platelets: Requesting crssmatched platelets is a different prcess than RBC crssmatching and it is imprtant t nte: - Unlike RBC crss-matching (dne n-site in ur bld bank), platelet crssmatching is perfrmed ffsite at the BCP Immunhematlgy reference lab, therefre needs mre careful crdinatin between bld bank and clinical services. - If yu suspect yur patient is allimmunized, perfrm 10 min-1 hur psttransfusin platelet cunts. If yur patient still shws inadequate increments, please cntact the lab medicine/bld bank resident at (r pager ) as sn as pssible t discuss the case and pssible need fr platelet crss-matching. - If the lab medicine/bld bank apprves crssmatching, yu may rder the test in APeX as fllws: Order Miscellaneus Outside Lab Test Pririty: STAT Test Descriptin: Platelet Crssmatch Cntainer details: 2 large lavender tp tubes Additinal Infrmatin: draw and send t bld bank befre 10 AM n weekdays; sign and date bth tubes - Platelet crss-matching can nly be sent ut Mnday-Friday. PLEASE fllw the instructins f the Bld Bank Resident n when t rder the Platelet Crssmatch test. - Samples fr crss-matching shuld be received in the bld bank as early as pssible in the mrning f testing (definitely befre 10AM). - Each platelet crss-matching requires 2 large lavender tp tubes. Additinal Infrmatin: - Results f crssmatch testing are available the same afternn, but actual platelet prducts may becme available slightly later (usually the next day after results are available, but smetimes the night f the crssmatch), given the time required t cmplete bacterial and infectius marker testing. - Shelf-life f platelets is significantly shrter than an average RBC unit: 4 March 2014

5 Platelet shelf-life is 5 days frm day f dnatin, but at least 2 days f this will be dedicated t infectius disease and bacterial screening. Therefre by the time a unit is available fr transfusin the shelf-life is nly 1-3 days. In cntrast, RBC shelf-life is 35 r 42 days (depending n anticagulant used) Transfusing Crss-Matched and HLA-Cmpatible Platelets It is VERY imprtant t cntinue checking 10 min-1 hur platelet cunts after EACH crss-match r HLA-cmpatible unit. This is especially useful fr patients with a significant degree f all-reactivity. Patients respnd differently t each transfused unit and ccasinally, there is discrepancy between in vitr crssmatching r HLA antibdy cmpatibility, and in viv respnses t varius dnrs. Perfrming the pst cunt will allw the bld bank and BCP t identify dnrs that have prven t be mst cmpatible clinically, and therefre prvide the best units fr the patient. Such dnrs can ften be recruited and are willing t repeatedly dnate fr the patient (histrically cmpatible). Useful review articles n platelet refractriness: - Nvtny, VMJ. Preventin and management f platelet transfusin refractriness. (1999) Vx Sanguinis, 76: Slichter, SJ. Algrithm fr managing the platelet refractry patient. (1997) J Clin Apheresis, 12:4-9 - Dzik, S. Hw d I: platelet supprt fr refractry patients. (2007) Transfusin, 47: March 2014