Overview
Definition:
Central venous catheter (CVC) thrombosis in pediatrics refers to the formation of a blood clot within or around a CVC, obstructing blood flow and potentially leading to catheter dysfunction or serious complications
This can involve thrombus formation on the catheter surface, within the lumen, or extending into the central veins.
Epidemiology:
The incidence of CVC-related thrombosis in pediatric patients varies widely, ranging from 2% to over 50%, depending on patient population (e.g., oncology, critical care), catheter type, duration of use, and diagnostic methods employed
Prematurity, underlying malignancy, sepsis, and inherited thrombophilias are significant risk factors.
Clinical Significance:
CVC thrombosis is a common complication in critically ill or chronically ill children requiring vascular access
It can lead to loss of access, increased morbidity (pain, swelling, venous distension, post-thrombotic syndrome), catheter-related infections, and, in severe cases, pulmonary embolism or stroke
Early recognition and appropriate management are crucial for optimizing patient outcomes and preserving venous capital.
Clinical Presentation
Symptoms:
Signs of CVC thrombosis may include absent or sluggish blood return from the catheter
Edema or swelling of the ipsilateral limb or face
Engorgement of superficial veins in the affected area
Pain or tenderness along the catheter tract or in the limb
Fever or signs of local infection (erythema, purulence) may also be present, though not always directly due to thrombosis itself.
Signs:
Physical examination may reveal a palpable venous cord, limb asymmetry in size, palpable lymphadenopathy, or a positive Homan's sign (though unreliable)
Vital signs may be normal, but tachycardia or tachypnea could suggest a more widespread thrombotic event like PE
A non-functioning or partially functioning catheter on aspiration is a key clinical clue.
Diagnostic Criteria:
Diagnosis is typically made based on clinical suspicion combined with imaging
While there are no formal diagnostic criteria for CVC thrombosis itself akin to DVT, a combination of the following is used: clinical signs and symptoms suggestive of thrombosis, and positive findings on vascular imaging
Catheter tip cultures are essential to rule out catheter-related bloodstream infection (CRBSI).
Diagnostic Approach
History Taking:
Key history points include duration of catheterization, catheter type and insertion site, underlying medical conditions (malignancy, cardiac disease, inflammatory conditions), history of previous thrombosis or thrombophilia, and recent immobility or trauma
Inquire about any changes in catheter function or associated symptoms.
Physical Examination:
A thorough physical examination should focus on the insertion site, the ipsilateral limb/extremity for edema, erythema, tenderness, and venous distension
Palpate for venous cords
Assess for signs of systemic illness or pulmonary embolism
Examine the integrity of the skin over the catheter tract.
Investigations:
The gold standard for diagnosis is ultrasound with Doppler of the suspected venous segment and the catheter tip
Echocardiography may be used for suspected superior vena cava (SVC) or right atrial thrombus
Laboratory investigations may include a complete blood count (CBC), coagulation profile (PT/INR, aPTT), D-dimer (less sensitive in pediatrics), and possibly thrombophilia workup if recurrent thrombosis is suspected
Catheter tip cultures are crucial if infection is suspected.
Differential Diagnosis:
Other causes of arm or leg swelling and pain in a child with a CVC include cellulitis, local trauma, allergic reaction to the catheter or infusate, superior vena cava syndrome (due to extrinsic compression), or venous stenosis (post-inflammatory or post-radiation)
Differentiating between catheter-related thrombosis and CRBSI is critical.
Management
Initial Management:
If CVC thrombosis is suspected and the catheter is functioning, attempts to aspirate sluggish blood or administer thrombolytics may be considered
If the catheter is not essential, removal may be the first step, followed by anticoagulation
If the catheter is essential for life-saving therapy, it may be left in situ while anticoagulation is initiated, with careful monitoring.
Medical Management:
Anticoagulation is the cornerstone of management for confirmed CVC thrombosis
In pediatric patients, unfractionated heparin (UFH) or low-molecular-weight heparin (LMWH, e.g., enoxaparin) are commonly used
LMWH is often preferred for its predictable pharmacokinetics and subcutaneous administration
Dosing is typically weight-based and adjusted based on PTT (for UFH) or anti-Xa levels (for LMWH)
Thrombolytic therapy with agents like alteplase (tPA) may be used for occluded catheters to restore patency, administered as a continuous infusion or dwell time
Warfarin may be used for longer-term anticoagulation after initial heparin therapy, with target INR 2-3.
Surgical Management:
Surgical intervention is rarely indicated for CVC thrombosis itself
It may be considered in rare cases of extensive thrombosis causing severe limb ischemia, or for removal of large thrombi that cannot be managed with anticoagulation or thrombolysis
Catheter removal with or without surgical thrombectomy may be an option.
Supportive Care:
Supportive care includes pain management, elevation of the affected limb, and meticulous monitoring for signs of extension of thrombosis or complications like pulmonary embolism
Compression stockings may be used once acute swelling subsides for post-thrombotic syndrome
If CRBSI is present, prompt antibiotic therapy is initiated.
Complications
Early Complications:
Catheter dysfunction (occlusion)
Catheter-related bloodstream infection (CRBSI)
Extension of thrombus into proximal veins
Pulmonary embolism (PE)
Swelling and pain in the affected limb.
Late Complications:
Post-thrombotic syndrome (chronic venous insufficiency)
Venous stenosis or occlusion
Development of new thrombotic events
Recurrence of thrombosis.
Prevention Strategies:
Use of maximal sterile barrier precautions during insertion
Optimal catheter tip placement
Avoiding unnecessary dwell time
Diligent catheter care and flushing protocols
Prompt removal of catheters when no longer needed
Careful selection of insertion sites to minimize risk to central veins
Education of healthcare providers on CVC care.
Prognosis
Factors Affecting Prognosis:
The prognosis depends on the extent of thrombosis, the presence of underlying thrombophilia, the speed and appropriateness of treatment, and the presence of complications such as PE or CRBSI
Early diagnosis and treatment generally lead to better outcomes and preservation of venous function.
Outcomes:
With prompt and appropriate anticoagulation and/or thrombolysis, most pediatric patients achieve resolution of catheter thrombosis and restoration of catheter function
Complete resolution of thrombus may take weeks to months
However, some may develop long-term sequelae like post-thrombotic syndrome.
Follow Up:
Follow-up includes monitoring for signs and symptoms of recurrent thrombosis or post-thrombotic syndrome
In cases with significant thrombophilia, prolonged anticoagulation and specialist hematology follow-up may be required
Regular reassessment of vascular access needs is also important.
Key Points
Exam Focus:
Remember that absent or sluggish blood return is the most common sign of CVC thrombosis
LMWH is often the preferred initial anticoagulant in pediatrics due to its predictability
D-dimer is less reliable in children
Ultrasound with Doppler is the primary diagnostic modality.
Clinical Pearls:
Always consider CVC thrombosis in a child with a central line presenting with unexplained limb swelling or pain
Differentiate between catheter occlusion due to fibrin sheath vs
intraluminal clot vs
external compression
Do not blindly remove a central line if it is essential for therapy
assess for thrombosis and manage accordingly.
Common Mistakes:
Delaying diagnosis by attributing symptoms solely to infection or catheter malfunction without imaging
Inadequate anticoagulation dosing or duration
Failure to consider underlying thrombophilias in recurrent cases
Over-reliance on D-dimer for diagnosis in pediatric patients.