Antithrombotic Therapy in Children: Antiplatelet Therapy in Pediatric Patients

Antithrombotic Therapy in Children: Antiplatelet Therapy in Pediatric PatientsAdverse Effects of Oral Anticoagulants: Bleeding is the main complication of oral anticoagulants. Minor bleeding, which is of minor clinical consequence (bruising, nosebleeds, heavy menses, coffee-ground emesis, microscopic hematuria, bleeding from cuts and loose teeth, ileostomy), occurs in approximately 20% of children receiving oral anticoagulants (one level IV study). The risk of serious bleeding in children receiving oral anticoagulants for mechanical prosthetic valves is acceptable at <3.2/% patient-years (13 level V studies) (see below). Significant bleeding complications occur in approximately 1.7% of children receiving oral anticoagulants for secondary prevention.
Nonhemorrhagic complications of oral anticoagulants, such as tracheal calcification or hair loss, have been described on rare occasions in young children. Although oral anticoagulants do not affect bone density in adults, the effects on children have not been assessed. At this time, there are no other serious complications of oral anticoagulants reported in the pediatric population. buy allegra online

Treatment of Oral-Anticoagulant-Induced Bleeding: Vitamin K is the antidote for oral anticoagulants. The dose to be administered and concurrent use of vitamin-K-depen-dent factor replacement (either fresh frozen plasma or prothrombin complex concentrates) are dependent on the clinical problem. Table 8 provides guidelines for reversal of oral anticoagulant therapy in children with no bleeding and those with significant bleeding.
Antiplatelet Therapy in Pediatric Patients
Age-Dependent Features: Compared to platelets from adult control subjects, neonatal platelets are hyporeactive to thrombin, adenosine diphosphate (ADP)/epinephrine, and thromboxane A2. This hyporeactivity of neonatal platelets is the result of a defect intrinsic to neonatal platelets. Paradoxically, the bleeding time is short in newborns, due to increased RBC size, high hematocrit values, and increased levels and multimeric forms of von Willebrand factor. No studies of platelet function in healthy children were identified, except for the bleeding time, which, relative to adults, is prolonged throughout childhood according to two of three studies. These physiologic differences suggest that the optimal dosage of antiplatelet agents in newborns and children may also differ from that in adults.
Table 8—Reversal of Oral Anticoagulation Therapy

1. No bleeding
A) Rapid reversal of oral anticoagulants is necessary and the patient will require oral anticoagulants again in the near future: give vitamin K, 0.5 to 2 mg subcutaneously or IV (not intramuscularly), depending on the patient’s size.
B) Rapid reversal of oral anticoagulants is necessary and the patient will not require oral anticoagulants again: vitamin Kx 2-5 mg subcutaneously or IV (not intramuscularly).
2. Significant bleeding
A) Significant bleeding that is not life-threatening and will not cause morbidity: treat with vitamin Kx as in 1A plus FFP (20 mL/kg IV).
B) Significant bleeding that is life-threatening and will cause morbidity: treat with vitamin Kx IV (5 mg) by slow infusion over 10-20 min because of the risk of anaphylactic shock. Consider giving prothrombin concentrate (containing factors II, VII, IX, X), 50 U/kg IV rather than FFP (20 mL/kg IV).