Hematology Flashcards
Depletion of which clotting components is responsible for bleeding associated with massive transfusion reactions?
A) Fibrinogen and platelets
B) Factors II, VII, IX, X and platelets
C) Factors V, VII
D) Fibrinogen, factors V, VIl and platelets
D) Fibrinogen, factors V, VIl and platelets
Massive transfusion is defined as the replacement by transfusion of more than 50% of the blood volume in 12 to 24 hours. This can result in a multifactorial coagulation defect, with the underlying problem being washout of coagulation proteins and platelets. Other possible complications of massive transfusion include hypothermia, acidosis, and hypocalcemia. Clotting factors and platelets suffer quantitative and qualitative losses in banked whole blood, so a similar clinical picture can emerge when whole blood rather than packed red blood cells are used. As a general rule, in children who weigh more than 30 to40 kg, 4U of platelets (or half of an apheresis unit), and 1 U of fresh-frozen plasma should be given for every 5 U of blood delivered. In smaller children, 10 ml/kg of platelets and 10 to 15 ml/kg of fresh-frozen plasma should be given for every 40 to 50 ml/kg of blood transfused. If the fibrinogen is low, cryoprecipitate also may be needed. Persistent bleeding after factor and platelet repletion suggests another etiology of the bleeding.
Factors II, VII, IX and X are the vitamin K-dependent factors. Selective deficiency of these factors suggests liver disease. Factors V and VII have the shortest shelf life in banked blood, but massive transfusion depletes fibrinogen and platelets as well.
Describe symptoms and management of engraftment syndrome in HSCT
Fever, rash, pulmonary involvement 10-20 days after transplant
May also see: weight gain, AKI, diarrhea
Due to pro-inflammatory surge with neutrophil recovery
Treat with corticosteroids
Which of the following statements about heparin-induced thrombocytopenia (HIT) type Il is true?
A) Thrombotic risk persists until platelet counts return to normal.
B) It does not occur with exposure to heparin-bonded central venous catheters.
C) The pathophysiology includes antibody formation against an antigenic compound composed of heparin and platelet factor 4.
D) Heparin-induced aggregation study is the gold standard for diagnosis.
C) The pathophysiology includes antibody formation against an antigenic compound composed of heparin and platelet factor 4.
There are two types of heparin-induced thrombocytopenia (HIT). Type I is a nonimmune asymptomatic transient thrombocytopenia that occurs in some patients treated with heparin. HIT type Il is a serious, immune-mediated prothrombotic process, potentially leading to significant morbidity and mortality. It can develop after exposure to any form of heparin delivered in any fashion, including therapeutic, unfractionated heparin, low-molecular-weight heparin for deep vein thrombosis prophylaxis, or exposure to heparin-bonded central catheters. The platelet count usually falls within 7 to 14 days of exposure. After all exposure to heparin is discontinued, counts usually return to normal within 1 week; however, the thrombotic risk persists for weeks.
Thrombocytopenia results from the clearance of platelets after antibodies form a heparin-platelet factor 4 complex. Thrombotic conditions develop when the binding of the heparin-platelet factor 4 antibody to the platelet results in platelet activation and release of prothrombotic platelet-derived microparticles.
There are two basic assays for diagnosis of HIT type II. The heparin induced platelet aggregation study is more widely available and technically easier. However, 14C-serotonin release assay is considered the gold standard.
A 7-month-old male infant with trisomy 21 has been in the cardiac ICU on a ventilator for the past 4 months. His initial surgical procedure was tetralogy of Fallot and AV canal repair at 3 months, followed by replacement of his mitral valve at 5 months. Recently, he was started on vancomycin, ceftriaxone, and fluconazole for fever and leukocytosis, digoxin for a run of supraventricular tachycardia, and polyethylene glycol 3350 for constipation. His other medications include warfarin, enalapril, spironolactone, and furosemide. His INR, which had been consistently 2.5, is now 4. Which of the following drugs is responsible for the prolonged INR?
A) Vancomycin
B) Ceftriaxone
C) Fluconazole
D) Digoxin
E) Polyethylene glycol 3350
C) Fluconazole
Inducers and inhibitors of hepatic biotransformation are important causes of drug interactions. Fluconazole is not metabolized by the cytochrome P450 system but impairs phenytoin and warfarin metabolism by potent inhibition of CYP2C enzymes. Fluconazole also inhibits metabolism of numerous drugs that are substrates of the CYP3A enzyme system. Starting fluconazole was the cause of increased INR in this patient.
(End of Year Wrap Up)
In a child with methemoglobinemia, what is the pulse oximeter reading most likely to be?
A) The same as the true saturation
B) Higher than true saturation
C) Lower than true saturation
D) It varies, depending on the tissue perfusion
E) It depends on the hemoglobin concentration
B) Higher than true saturation
Pulse oximeter technology uses only two wavelengths of light for saturation measurements, which does not allow differentiation of oxyhemoglobin from carboxyhemoglobin and methemoglobin. Cooximetry, however, uses four wavelengths of light, which can identify carboxyhemoglobin and methemoglobin. Carboxyhemoglobin is read by pulse oximetry as oxyhemoglobin; patients can be significantly hypoxemic with normal pulse oximetry readings. Methemoglobin depresses pulse oximeter readings, but the relationship between methemoglobin level and pulse oximetry reading is not linear, and pulse oximeter saturations level out at 85% after which further decreases in methemoglobin concentration do not cause further decreases in pulse oximetry readings.
(End of Year Wrap Up)
Which of the following statements regarding stroke in pediatric patients with sickle cell is true?
A) Emergent transfusion with simple packed red blood cells
B) CT is more beneficial than MRI in the detection of early ischemic parenchymal changes.
C) Silent cerebral infarction occurs in up to 25% of patients younger than 20 years of age.
D) Most strokes in this patient population are hemorrhagic.
C) Silent cerebral infarction occurs in up to 25% of patients younger than 20 years of age.
(End of Year Wrap Up)
A 10-year-old boy who underwent a hematopoietic stem cell transplant 15 days ago is transferred to the ICU with increased respiratory distress. Over the past 5 days, right upper quadrant pain, hepatomegaly, ascites, peripheral edema, and pleural effusions have developed. An ultrasound of the liver shows attenuated hepatic venous flow. What is the most likely etiology of the patient’s clinical findings?
A) Sepsis
B) Disseminated cvtomegalovirus
C) Superior vena cava svndrome
D) Veno-occlusive disease
E) Acute graft-versus-host disease
D) Veno-occlusive disease
(End of Year Wrap Up)
A 10-day-old infant presents with a subdural hemorrhage following minor trauma. Further history reveals that the child was bornat home and has not yet been seen by a medical provider. Coagulation studies reveal a prolonged PT, normal aPTT, and normal platelets. What clotting factors are most likely to be deficient in this infant’s coagulopathy?
A) I, V, VII, IX
B) II, V, VII, IX
C) II, VII, VIII, X
D) II, VII, IX, X
E) II, IX, X, XIII
D) II, VII, IX, X
(End of Year Wrap Up)
Which of the following laboratory findings is typically found in hemophagocytic lymphohistiocytosis?
A) Hypotriglyceridemia
B) Hypoferritinemia
C) Hyperfibrinogenemia
D) Low soluble CD25 (soluble IL-2 receptor)
E) Low NK-cell activity
E) Low NK-cell activity
(End of Year Wrap Up)
Which of the following is a key component of the pathophysiology of disseminated intravascular coagulation in sepsis?
A) Proteins C and S are increased.
B) Tissue factor drives thrombin formation.
C) The primary process is activation of the intrinsic pathway.
D) Thrombin is rapidly inactivated by antithrombin III (AT-Ill)
B) Tissue factor drives thrombin formation.
(End of Year Wrap Up)
A 1-year-old male infant with a 6-day history of diarrhea is admitted to the ICU due to persistent hypoxia. He is cyanotic, with an Sp0 2 of 85% that was minimally responsive to supplemental 02. A chest radiograph is normal, as is his cardiac examination. An ECHO shows no anatomic heart disease. Arterial blood gas values are as follows: pH 7.39, PaC02 40 mm Hg, Pa02 95 mm Hg on room air. Which of the following statements about the evaluation and management of this child’s condition is true?
A) His blood will appear cherry red when exposed to air.
B) The antidote includes amyl nitrite, sodium nitrite, and sodium thiosulfate.
C) Serial co-oximetry readings should be obtained to monitor the effects of therapy.
D) The underlying mechanism is oxidation of the hemoglobin molecule from the ferrous to the ferric form
D) The underlying mechanism is oxidation of the hemoglobin molecule from the ferrous to the ferric form
(End of Year Wrap Up)
A 4-year-old girl who has a history of hemoglobin SS disease presents with fever, cough and tachypnea, which quickly progresses to hypoxic respiratory failure requiring intubation. A CBC reveals a WBC of 28,000 cells/pL, hemoglobin of 7 g/dL, hematocrit of 21%, and a platelet count of 110,000 cells/pL. Arterial blood gas values are as follows: pH 7.28, PaC02 58 mm Hg, Pa02 58 mm Hg on Fi02 1.0, and PEEP 10 cm H20. What is the first most appropriate step in management?
A) Fluid restriction
B) Sedation with midazolam infusion
C) Antibiotic coverage with gentamicin
D) Transfusion with packed red blood cells to a hemoglobin of 10 g/dL
D) Transfusion with packed red blood cells to a hemoglobin of 10 g/dL
(End of Year Wrap Up)
How does CAR T-cell therapy work?
CAR T-cells are genetically modified autologous T-cells directed at the B-lymphocyte antigen CD19, stimulates T-cell activation to recognize target cells (ALL blasts)
Cytokine release syndrome from CAR-T cell therapy
Risk of toxicity higher with higher disease burden
CRS within first 7-10 days after infusion, release of cytokines including IFN gamma, IL-5, IL-6, IL-10, granulocyte-macrophage colony-stimulating factor
Signs: fever, myalgia, headache, hypotension, MODS, capillary leak
Treatment: tocilizumab (IL-6), steroids in severe cases
ICANS: delirium, hallucinations, tremors, AMS, language disturbance, seizures, encephalopathy, rarely cerebral edema
ICANS can be in first 6-8 weeks after infusion
Management includes supportive care and use of corticosteroids - methylprednisolone (tocilizumab doesn’t cross BBB), siltuximab (direct IL-6 antagonist that may prevent IL-6 from entering CNS), seizure prophylaxis with keppra
CSF: elevated IL-6, increased CAR-T cells
Severe CRS can evolve into HLH/MAS
One of the main side effects of vincristine?
Neuropathic pain
Inhibition of microtubule polymerization and subsequent destruction of peripheral neuronal axon
Treatment: tricyclic antidepressants, SNRIs, gabapentin/pregabalin, ketamine, methadone, lidocaine, topical capsaicin, spinal or peripheral nerve blocks
Scrambler therapy (electrical pulses on skin)
