How to manage severe thrombocytopenia (low platelet count) in a patient on Extracorporeal Membrane Oxygenation (ECMO)?

Management of Severe Thrombocytopenia on ECMO

For patients on ECMO with severe thrombocytopenia, maintain platelet counts >100,000/μL through aggressive platelet transfusion, maintain hemoglobin >10 mg/dL, fibrinogen >200 mg/dL, and antithrombin III >1 U/mL, while continuing anticoagulation with heparin to maintain ACT 180-220 seconds. 1

Platelet Transfusion Threshold

The American Heart Association explicitly recommends maintaining platelet count >100,000 per mm³ in ECMO patients, particularly those with postcardiotomy support or ongoing bleeding risk. 1 This is a higher threshold than general critical care because:

• ECMO circuits expose blood to large foreign surface areas, creating simultaneous thrombotic and bleeding risks 1
• Thrombocytopenia on ECMO is associated with increased bleeding events and reduced survival, with even mild thrombocytopenia (100-149×10⁹/L) increasing bleeding risk by 61% 2
• Recent multicenter data shows a linear relationship where each 10×10⁹/L decrease in platelet count increases bleeding risk by 3.7% 2

Anticoagulation Management During Severe Thrombocytopenia

Continue heparin anticoagulation targeting ACT 180-220 seconds even with severe thrombocytopenia, while providing platelet transfusion support. 1 The rationale:

• Stopping anticoagulation risks catastrophic circuit thrombosis and patient thromboembolism 1
• Autopsy studies show one-third of ECMO patients develop venous thrombus and systemic emboli, most undetected before death 1
• While ECMO without anticoagulation is technically feasible using heparin-bonded circuits, it carries grim prognosis with only 14% survival in one series 3

Monitor beyond ACT alone: Check anti-Factor Xa levels (target 0.3-0.7 U/mL), PTT (1.5-2.5× control), fibrinogen, and antithrombin III levels at least daily. 1

Comprehensive Hematologic Support

Beyond platelets, aggressively correct all coagulation deficiencies: 1

• Hemoglobin >10 mg/dL - Maintain with packed red blood cell transfusion
• Fibrinogen >200 mg/dL - Replace with cryoprecipitate or fibrinogen concentrate
• Antithrombin III >1 U/mL - Supplement with fresh frozen plasma or AT III concentrate, especially in infants <1 year who commonly develop AT III deficiency 1

Surgical Bleeding Control

Every effort must be made to identify and surgically control bleeding sites - this is the single most important intervention for bleeding on ECMO. 1 Medical management alone is insufficient when surgical bleeding persists. Ongoing bleeding despite transfusion support is associated with poor survival. 1

Antifibrinolytic Therapy

Consider epsilon-aminocaproic acid (EACA) for persistent bleeding: loading dose 100 mg/kg followed by 30 mg/kg/hour infusion for up to 72 hours. 1 However, be aware that fatal thrombosis has been reported with this regimen in neonates. 1

Recombinant Factor VIIa (90 μg/kg) may reduce bleeding but carries significant thrombotic risk including oxygenator occlusion requiring emergent circuit change and limb ischemia requiring amputation. 1 Reserve this for life-threatening hemorrhage only.

Heparin-Bonded Circuits

Consider heparin-bonded ECMO circuits with minimal heparinization as a strategy to decrease bleeding risk in high-risk patients. 1 Small series show some patients can be maintained for extended periods with reduced or no systemic heparin using these circuits. 1

Critical Pitfalls to Avoid

• Never rely on ACT alone - It must be confirmed with anti-Factor Xa and PTT levels 1
• Do not withhold heparin loading dose if patient is already anticoagulated from cardiopulmonary bypass, as additional heparin increases bleeding risk 1
• Suspect antithrombin III deficiency if escalating heparin doses are needed to maintain target ACT, especially in infants 1
• Visually inspect the ECMO circuit regularly for clot formation regardless of laboratory values 1

Special Consideration: Heparin-Induced Thrombocytopenia

If HIT is suspected (typically after 5+ days of heparin exposure with platelet drop), switch to argatroban as an alternative anticoagulant. 4 This direct thrombin inhibitor has been successfully used in adult ECMO patients with HIT.

Prognosis

Recent pediatric data suggests that severe thrombocytopenia (<50×10⁹/L) during ECMO, while associated with increased in-hospital mortality, does not increase on-ECMO mortality or prolong ECMO duration. 5 However, adult immunocompromised patients with severe thrombocytopenia requiring ECMO without anticoagulation have dismal outcomes with only 14% survival. 3