As stated previously, patients with heterozygote deficiencies are usually protected during childhood, except in the presence of a secondary challenge such as a CVL. The reported incidence of inherited prothrombotic disorders in children with DVT/PE varies from 10 to over 60%. In children with cancer and DVT/PE, the reported incidence is 3%, the incidence of CVL-related DVT/PE is 83% and the incidence of congenital heart disease and DVT/PE is 56% (n = 32, 18, 9, respectively). These three studies varied in design from retrospective case series to prospective cohort studies. In particular, different definitions of prothrombotic disorders (for example, some included elevated lipoprotein plasma levels) and different patient selection procedures (idiopathic or secondary) make the true incidence of prothrombotic disorders in children with DVT/PE uncertain. Screening for prothrombotic disorders in children with thrombosis, regardless of the presence or absence of clinical risk factors, is probably worthwhile. The role of screening children with major illnesses, or, for example, children about to have a CVL inserted, in order to administer prophylaxtic therapy is unknown.
Although there is agreement on the initial treatment of DVT/PE in children with anticoagulants and on the need for prophylaxis in high-risk situations, there is a paucity of information on the risks and benefits of long-term prophylaxis versus careful monitoring with intermittent prophylaxis. Further studies are required. ventolin inhaler
Homozygous PC or PS Deficiency
In contrast to heterozygous PC or PS deficiency, homozygous PC/PS deficiency presents within hours of birth with purpura fulminans, cerebral and/or ophthalmic damage which occurred in utero, and, on rare occasions, large vessel thrombosis. Purpura fulminans is an acute, lethal syndrome of rapidly progressive hemorrhagic necrosis of the skin due to dermal vascular thrombosis. Since 1980, 44 patients with homozygous PC deficiency and 1 patient with homozygous PS deficiency were reported in the literature (references available upon request). Thirty-three patients presented in the neonatal period and eight as children or adults. All patients presenting at birth with purpura fulminans had undetectable levels of PC or PS, whereas patients with delayed presentation had detectable levels of PC, ranging from 0.05 to 0.20 U/mL. These children usually presented with DVT following a minor secondary insult and developed oral-anticoagulant-induced skin necrosis.