CH 139 Preservation and Clinical Use of Platelets Flashcards
The expected response to a prophylactic platelet transfusion in nonrefractory thrombocytopenic patients is assessed by two parameters:
(1) the number of platelets that circulate immediately after transfusion,
measured by platelet recovery
(2) the survival time of the transfused platelet
measured by days to next transfusion
(1) the number of platelets that circulate immediately after transfusion,
is measured by
by platelet recovery
(2) the survival time of the transfused platelet is measured by
days to next transfusion
Platelets circulate for a shorter time in thrombocytopenic patients (____days) compared with normal subjects (____ days)
≤5
8–10
mechanisms by which platelets are lost from circulation:
(1) senescence- platelets are removed by the mononuclear phagocyte system
(2) random- platelets are consumed during hemostasis to provide endothelial support
random platelet loss is about _____ platelets/L per day
7.1 × 10^9
T/F
the more thrombocytopenic a patient is, the higher the percentage of their circulating platelets that will be removed by senescence versus randomly
False
the more thrombocytopenic a patient is, the higher the percentage of their circulating platelets that will be removed randomly versus lost by senescence
1 random donor PC contains on average_____platelets, the daily requirement for endothelial support should be 1 PC/day
8.3 × 10^10
the daily platelet requirement for endothelial support should be ____PC/day
1
______platelets is needed daily for endothelial support
4.8 × 10^10
Incidence of spontaneous bleeding increases at platelet counts____ in children with acute leukemia
< 100 × 109/L
Major bleeding more common below platelet count of ____, as high as ___%
5 × 109/L
33
T/F
Life-threatening bleeding rarely occurs above platelet counts of 5 × 109/L to 10 × 109/L without disruption of the vessel wall.
True
conducted to better understand the effects of platelets dosage in prophylactic transfusion on clinical signs of bleeding, the use of platelet and red-cell transfusions, changes in the recipient’s post-transfusion platelet count, days to next transfusion, and adverse events.
PLADO trial
PLADO trial
T/F
the low platelet transfusion dose led to a decreased number of platelets transfused per patient and a lower number of transfusions given
FALSE
the low platelet transfusion dose led to a decreased number of platelets transfused per patient, but an increased number of transfusions given
PLADO Trial
T/F
Platelet doses between 1.1 x 1011/m² and 4.4 x 1011/m² had no significant effect on the incidence of bleeding in patients with hypoproliferative thrombocytopenia.
T
World Health Organization (WHO) bleeding scale. Describe.
WHO 1-2-2a-3-4
WHO Grade 1 bleeding: noticeable, no clinical significance
WHO Grade 2 bleeding, which requires some minor intervention to control bleeding,
WHO Grade 2a: Grade 2 bleeding excluding skin manifestations
WHO Grade 3: Bleeding requires red cell transfusion related
to treatment of bleeding
or
Significant intervention to treat bleeding, eg, endoscopy or surgery
WHO Grade 4: Bleeding that is fatal or life- threatening
Platelet Transfusion Therapy in Hematologic Malignancy
T/F
There is disturbance of endothelial integrity that frequently occurs with aggressive therapies.
Inflammation can induce hemorrhage in periods of thrombocytopenia
Mucositis, GVHD, infection, and organ dysfunction can all increase daily platelet consumption and negatively affect posttransfusion platelet increments and lifespan
T-T-T
A platelet transfusion threshold of _____ in stable patients has been recommended
less than 10 × 109/L
T/F Patients with active infection or fever, or those who are bleeding may require higher transfusion thresholds.
T
T/F
a decrease in the number of platelet transfusions administered in the therapeutic only arms compared with the prophylactic transfusion arms, this strategy is safe in the majority of patients undergoing HSCT or induction chemotherapy for acute leukemia
FALSE
a decrease in the number of platelet transfusions administered in the therapeutic only arms compared with the prophylactic transfusion arms, this strategy CANNOT be considered safe in the majority of patients undergoing HSCT or induction chemotherapy for acute leukemia
______ platelets are used daily to maintain endothelial integrity in an individual weighing 70 kg with an est. blood volume of 5 L
4.8 × 10^10
current standard dose of 2.2 × 1011 platelets/m2
equivalent to ____ or______
equivalent to 4–6 pooled PC or 1 apheresis platelet
T/F
In PLADO study, low-dose therapy may be the most cost-effective strategy, at least during hospitalization
T
major risk of platelet storage at 22 °C
bacterial overgrowth
T/F
once platelets have been stored beyond 5 days, there is little increased risk from bacterial overgrowth
True
The FDA has approved platelet storage for up to____ days provided the use of approved bacterial detection testing or pathogen reduction technology.
7
When platelets are stored in a platelet additive solution, the longest storage times achieved is ____ days
6
platelets were collected by a Haemonetics apheresis machine could be stored for ____ days.
13
T/F.
lifespan of the platelet is not intrinsic to the cell
T
in normal subjects, fresh autologous platelet survivals are only____days.
8 to 10
T/F
the method of platelet collection may significantly affect storage duration
T
Two methods of pathogen reduction involve adding an agent prior to UV light exposure
adding amotosalen (Intercept system)
adding riboflavin (Mirasol system)
Effects of Mirasol and Intercept methods in platelets
reduction in posttransfusion autologous radiolabeled platelet recoveries and survivals by a 15% to 25%, vs with similarly stored nontreated platelets from the same subjects
can be effective for patients with severe allergic reactions, as well as critical for patients with IgA deficiency to prevent anaphylactic transfusion reactions
Washed platelets
- reduce the risk of allergic transfusion reactions
- do not appear to reduce the risk of febrile nonhemolytic transfusion reactions
Platelet Additive Solutions
T/F Posttransfusion CCIs are higher with PAS platelets compared with standard platelets
TRUE
Posttransfusion CCIs are lower with PAS platelets compared with standard platelets
Indication for platelet volume reduction
- for infants/young children in whom an adult volume may be excessive
- for patients with recurrent allergic reactions and febrile nonhemolytic transfusion reactions that are not mitigated by premedication
- when the recipient and donor have an ABO incompatibility
indications for γ-Irradiation of platelets
(a) patients receiving stem cell transplantation and/or fludarabine chemotherapy
(b) intrauterine transfusions
(c) granulocyte transfusions
(d) crossmatched, HLA-matched, or directed donation blood
(e) patients who are severely immunocompromised (due to treatment or disease or other factors)
(f) in populations that are genetically homogenous
T/F
transfusion study in thrombocytopenic patients:
- γ-irradiation decreased one-hour posttransfusion increments by 2.8 × 109/L and showed an increased HR of 1.45 for the development of platelet refractoriness
TRUE
Trial to Reduce Alloimmunization to Platelets
T/F
γ-irradiation prolonged the duration of HLA alloantibodies in patients in whom these antibodies developed during the course of their transfusions. hence, indiscriminate use of γ-irradiation should be avoided
TRUE
clear indications for providing leukoreduced platelet products:
(a) reduction of platelet alloimmunization,
(b) prevention of CMV transmission by transfusion,
(c) reduction in febrile transfusion reactions
The majority of transfusion reactions were ____ (46.8%), followed by ___ (36.1%).
allergic
febrile nonhemolytic transfusion reactions
T/F
Randomized placebo-controlled data suggest that premedication with acetaminophen and antihistamines alter the rate of allergic transfusion reactions
FALSE
Randomized placebo-controlled data suggest that premedication with acetaminophen and antihistamines does NOTalter the rate of allergic transfusion reactions
The major advantage of APs
enough platelets can be collected from a single donor to constitute a transfusion dose
The PLADO trial
T/F
absolute increments for random-donor, whole-blood platelets (rdWBPs) at 4 hours post transfusion were on average 3.5 × 109/L lower than AP, with no differences for these parameters at 24 hours
TRUE
T/F
Major ABO-incompatible (donor red cell A or B antigens incompatible with recipient’s anti-A or anti-B antibodies), AND minor ABO- incompatible (donor’s anti-A or anti-B antibodies incompatible with recipient’s red cell A or B antigens), transfusions were associated with lower increments of 2.2 × 109/L and lower CCIs of 1.4 × 109/L ) at 4 hours post transfusion.
False
Major ABO-incompatible (donor red cell A or B antigens incompatible with recipient’s anti-A or anti-B antibodies), BUT NOT minor ABO- incompatible (donor’s anti-A or anti-B antibodies incompatible with recipient’s red cell A or B antigens), transfusions were associated with lower increments of 2.2 × 109/L (P = .0001) and lower CCIs of 1.4 × 109/L (P < .0001) at 4 hours post transfusion,
T/F
At 24 hours post- transfusion, major ABO-mismatched transfusions had lower platelet increments of 2.6 × 109/L and CCIs were less by 1.8 × 109/L, but there was no effect of minor ABO incompatibility on these measurements at any time point.
TRUE
T/F
Transfusion intervals showed only minimal effects based on transfusion type (AP or rdWBP) and only for low-dose platelet transfusions (1.1 × 1011 platelets/m2), the interval was 3.9 hours less for ABO-major-mismatched transfusions.
TRUE
2 methods to prepare platelet concentrate from whole blood
Platelet-rich plasma (PRP) method
Buffy-coat (BC) method
The FDA requires at least _____ platelets/concentrate and ____ platelets/apheresis collection.
5.5 × 10^10
3.0 × 10^11
The incremental increase in platelet count after a platelet transfusion is dependent on (2)
platelet dose (number) and
patient’s blood volume
The corrected count increment (CCI), is generally measured _____ after a platelet transfusion
30 minutes to 1 hour
Platelet refractoriness is defined as patients who have (2)
CCI < 5 × 109/L on at least 2 consecutive occasions
2 sequential one-hour platelet increments of < 11 × 109/L
Formula for CCI
[(post-transfusion platelet count </μL>) - (pre- transfusion platelet count </μL>)] x (body surface area < m2>) / (number of platelets transfused < x1011/μL>).
most common cause of platelet refractoriness
non-immunologic
Trial to Reduce Alloimmunization to Platelets: factors that most likely resulted in platelet refractoriness, in order of frequency (8)
(a) developing lymphocytotoxic antibodies
(b) being male, or female with two or more pregnancies
(c) heparin administration
(d) fever
(e) bleeding [increased plt consumption]
(f) transfusion of γ-irradiated platelets
(g) receiving an increasing number of platelet transfusions
Patients who have been previously transfused or pregnant may fail to increase their platelet count after transfusion because of HLA antibodies directed against the ______ antigens on the platelet surface
class I HLA
T/F transfusion of platelets to ITP patients is appropriate only for life- or organ-threatening bleeding; platelets transfused survive only a few hours
TRUE
Platelet transfusion was associated with an increased risk of _____ thrombosis in patients with TTP and HIT, but not in patients with ITP
arterial
T/F clopidogrel have shorter half-lives, as do the active metabolites of these drugs, and may continue to affect platelets for more than 1 week
FALSE
clopidogrel have much longer half-lives, as do the active metabolites of these drugs, and may continue to affect platelets for more than 1 week
T/F
The impact of platelet transfusions is clear in patients taking antiplatelet agents who have preexisting thrombocytopenia and/or require surgical intervention for life-threatening bleeding
FALSE
The impact of platelet transfusions is less clear in patients taking antiplatelet agents who have preexisting thrombocytopenia and/or require surgical intervention for life-threatening bleeding
A target platelet counts of _____ should be used in life-threatening bleeding, such as intracerebral bleeding or diffuse alveolar hemorrhage, to minimize compromise of healthy tissue
100 × 109/L
For diffuse microvascular bleeding, platelet count of _____ are recommended but difficulties in obtaining timely results during massive hemorrhage make the feasibility of this approach unrealistic
100 × 109/L
In massive transfusion (>10 U/24 hours), a transfusion ratio of _____AP to ____ of red blood cells to be associated with significantly improved survival at 24 hours and 30 days in combat casualties requiring a MT within 24 hours of injury
1 AP platelet component to every 8 units (1:2)
Pragmatic Randomized Optimal Platelet and Plasma Ratios study
T/F Both 24-hour and 30-day mortality rates were significantly improved when the numbers of platelets and plasma transfusions were increased to a 1:1 ratio with red blood cell transfusions
T
At platelet counts of < 100 × 109/L, there is an _____relationship between platelet count and bleeding time; that is, as the platelet count decreases, the bleeding time increases
inverse
The need for a prophylactic platelet transfusion for an invasive procedure must consider: (4)
platelet count,
platelet function,
endothelial integrity,
consequences of prolonged bleeding
T/F
Abnormal coagulation parameters, drugs, or diseases (eg, uremia or modest to severe anemia) that inhibit platelet function should be corrected as much as possible before any procedure
T
CVP insertion
only patients with pre-procedure platelet counts below ______ were at increased risk of bleeding vs with counts > 100 × 109/L
20 × 109/L
LP can often be safely performed at platelet counts______
< 20 × 109/L
a bleeding patient post CABG may benefit from platelet transfusion, even in the setting of a normal platelet count as a result of the
effect of bypass on platelet function
T/F
TRAs is recommended as an adjunct to or replacement for platelet transfusions in patients with hypoproliferative thrombocytopenia
FALSE
TRAs cannot be routinely recommended as an adjunct to or replacement for platelet transfusions in patients with hypoproliferative thrombocytopenia
Platelet Transfusions in Neonates
T/F
patients who received transfusion(s) below the high threshold level 50 × 109/L had a lower rate of severe complications and bleeding than those patients in whom transfusion was held until the higher threshold level 25 × 109/L was reached
FALSE
patients who received transfusion(s) below the high threshold level 50 × 109/L had a higher rate of severe complications and bleeding than those patients in whom transfusion was held until the lower threshold level 25 × 109/L was reached
PLADO Study
Platelet transfusion intervals were significantly_____ in the higher-dose groups, resulting in_____transfusion events, which may make higher dose transfusions the preferred strategy for outpatients.
longer
fewer
