Guía de la American Heart Association (1996)

Management of Venous Thromboembolism in Children Venous thromboembolism in children is much less common than in adults. In general, recommendations for antithrombotic therapy have been extrapolated from those used for adults. However, optimal dosing for antithrombotic therapy in children is likely to differ from adults because the anticoagulant response to antithrombotic agents is different. Incidence Incidence of DVT/PE in the adult population is ~2.5% to 5.0%.2,54,245 In comparison, incidence of DVT/PE in the general pediatric population is reported to be 0.07 per 10 000 and 5.3 per 10 000 hospital admissions.246-248 Other comparisons illustrating the lower risk of DVT/PE during childhood are the <1% incidence of clinically apparent DVT/PE after lower limb or scoliosis surgery249 and the relative absence of DVT/PE in children with congenital thrombophilias.250,251 Clinical Features Ninety-five percent of DVT/PE in pediatric patients occurs as a complication of serious diseases such as prematurity, cancer, trauma/surgery, and congenital heart disease.250-253 Congenital prethrombotic disorders account for <10% of DVT/PE in children.250,251 Children at greatest risk for DVT/PE are younger than 1 year or teenaged.250-253 DVT in the lower extremities is the most frequent noncentral venous line thrombotic complication in children.251 The clinical presentations of DVT and PE are similar to those in adults.248,250,251,253 Central Venous Lines Forty percent of DVT in children and more than 80% in newborns occurs in the upper venous system secondary to use of central venous lines,250-252 which are employed for short-term intensive care or long-term supportive care in children requiring total parenteral nutrition or therapy for cancer. Central venous line-related DVT requires repeat anesthesia for replacement and can be complicated by PE254-257; it can cause superior vena cava syndrome257-261 and chylothorax257,258,262,263 and can obliterate the upper venous system264,265 and so lead to postthrombotic syndrome in the upper extremities. Treatment of Children Children older than 2 months who have DVT or PE should be treated with intravenous heparin (bolus 75 U/kg; initial maintenance of 20 U/kg per hour) sufficient to prolong the aPTT to a range that corresponds to an anti-factor Xa level of 0.3 to 0.7 U/mL. Treatment with heparin should be continued for 5 to 10 days and oral anticoagulation overlapped with heparin for 4 to 5 days. For many patients heparin and warfarin can be started together and heparin discontinued on day 6 if the INR is therapeutic. Heparin therapy should be used for a longer period for massive PE or iliofemoral thrombosis. Long-term anticoagulant therapy should be continued for at least 3 months, with oral agents (initial dose 0.2 mg/kg per day) to prolong PT to an INR of 2.0 to 3.0. Either indefinite warfarin therapy with an INR of 2.0 to 3.0, low-dose anticoagulant therapy (INR, <2.0), or close monitoring should be considered for children with a second recurrence of venous thrombosis or a continuing risk factor such as central venous line, antithrombin deficiency, or protein C or S deficiency. Newborns with a central venous line in place should be treated with intravenous heparin in doses of 1 to 5 U/h through the catheter.266-270 Treatment of Newborns The optimal regimen for anticoagulation therapy in treatment of newborns with DVT, PE, or arterial thrombosis is uncertain. If anticoagulation is indicated, a short course (10 to 14 days) of intravenous heparin (75 U/kg bolus; maintenance 28 U/kg per hour), sufficient to prolong the aPTT to an anti-factor Xa level of 0.3 U/mL, should be used. The role of thrombolytic agents in treatment of VTE is uncertain. Further clinical investigation is needed before more definitive recommendations can be made. If thrombolytic therapy is used, either urokinase or TPA is preferable to streptokinase, and supplementation with plasminogen may be helpful. nger half-life after subcutaneous injection, which allows administration once daily without frequent monitoring.244