VTE in Children (bsh 2011, Addendum 2021)

 

intro

Annual incidence: 1 per 100,000 children

>90% 2o to medical/surgical risk factors

Bimodal age distribution: Neonates & adolescents

 

Diagnostic Imaging

 

DVT

Lower limb: USS and repeat after 1 week if first scan normal

Blocked line: CXR, linogram +/- MRV

Central Vein: Contrast MRV (alt: CT)

 

PE

VQ if CXR normal

CT if VQ non-diagnostic (alt: MRA)

 

Cerebral Venous Thrombosis

Urgent T2* MRI and MRV (alt: Pre- and Post- contrast CT)

Conventional angiography if MRI non-diagnostic

 

Laboratory Investigation

 

FBC, U&E and PT/APTT for safety of anticoagulation

Antiphospholipid antibodies if unprovoked —> long term AC if positive

Protein C and S only if purpura fulminans

Antithrombin only if early onset of spontaneous thrombotic events

 

Do not test D-dimer

Do not test heritable thrombophilias, consequence of a positive result not clear

 

Management

 

VTE

LMWH followed by warfarin (INR 2.5), DOAC or continuous LMWH

  • 3 months if provoked

  • 6 months if idiopathic

  • Long term if Antiphospholipid antibodies or recurrent VTE

Consider thrombolysis if extensive clot

Remove lines 2-4 days after start LMWH

IVC filter only if AC contraindicated

 

Cerebral Venous Thrombosis

LMWH / UFH / DOAC if small, or no, intracranial haemorrhage

  • 3 months if provoked and trigger has resolved. Re-image at end of treatment

  • 6 months if idiopathic. Re-image at end of treatment

  • Long-term if risk factors persist

No AC if haemorrhage is intraventricular or causing mass effect

  • If no AC —> re-image to look for clot extension

Prophylaxis

Physical prophylaxis in older children who are at risk of VTE

LMWH prophylaxis if multiple risk factors

No prophylaxis for lines, but avoiding siting in femoral or subclavian veins.

 

UFH Dosing

Loading – 75 iu/kg over 10 minutes

Then - <1 year olds 28 iu/kg/hr, >1 year olds 20 iu/kg/hour

 

Dalteparin Dosing 

200 u/kg OD or 100 u/kg BD

50% larger dose if <8 weeks old or weight <5 kg (due to low antithrombin levels)

Prophylactic dose is half the treatment dose

 

Target Anti-Xa: 0.5-1.0 for treatment, 0.1-0.4 for prophylaxis

 

DOACs (BSH Addendum 2021) 

Trials for Rivaroxaban (EINSTEIN-Jr) and Dabigatran (DIVERSITY) now published and found these two DOACs to be non-inferior to standard of care. Trials for Apixaban and Edoxaban ongoing. The guideline discusses the limitations in some detail but concludes:

  • Rivaroxaban and dabigatran should be offered for the treatment of VTE in people <18 years old

  • Five day’s parenteral anticoagulation should be given before starting the DOAC

  • Recommend warfarin for triple-positive APS, and suggest an alternative to DOAC for non-triple APS.