How I treat venous thrombosis in children

Neonatal haemostasis and the management of neonatal thrombosis

“…Furthermore, using the APTT to assess the efficacy of UFH requires frequent blood sampling and that often creates practical difficulties in an ill newborn. Ideally anti-Xa activity would be a better assessment of UFH with an aim to achieve anti-Xa activity of between 0Á3-0Á7 u/ml (Manco-Johnson, 2006;Monagle et al, 2012;Saxenhouse, 2012). This is a lower range than for LMWH because of UFH's combined effect on thrombin and FXa.…”

“…UFH has both marked anti-thrombin and anti-Xa activity; the former being responsible for the increase in APTT that is traditionally used to monitor UFH's anticoagulant effect. APTT monitoring in neonates is problematical because of a raised baseline and a non-linear dose effect on the APTT seen in neonates (Manco-Johnson, 2006). Furthermore, using the APTT to assess the efficacy of UFH requires frequent blood sampling and that often creates practical difficulties in an ill newborn.…”

“…However it is well known that neonatal anti-Xa assays are prone to fluctuating results, with only 27% being within the desired therapeutic range in one study and yet, despite this, efficacy appears to be unaffected (Lulic-Botica et al, 2012). Heparin resistance can be addressed by further increases in dose or, if this strategy fails, by replacing ATIII by infusions of fresh frozen plasma; one paper described five neonates who received ATIII concentrate with good effect (Manco-Johnson, 2006).…”

“…It is clear from the more recent literature that with increasing experience in the use of rTPA, these contraindications are no longer considered to be absolute. Recombinant tissue plasminogen activator is most often administered systemically but it can by also be locally infused directly into the affected blood vessel (Manco-Johnson, 2006;Williams, 2009). rTPA is also very effective when instilled at low dose to unblock central lines.…”

“…This is the cause of heparin resistance seen during the neonatal period. The aim is to achieve a 4-h post-dose anti-Xa concentration of between 0Á5-1Á0 u/ml (Manco-Johnson, 2006;Monagle et al, 2012;Saxenhouse, 2012). Premature neonates require even higher doses than term babies (Monagle et al, 2012).…”