- The development of coagulopathy in severely ill COVID-19 patients is a marker of poor prognosis.
- Coagulopathy associated with COVID-19 may have features of both DIC and thrombotic microangiopathy (TMA).
- Micro-thrombosis has been identified on lung and renal pathology on postmortem examination of COVID-19 patients but there is no evidence to initiate therapeutic anticoagulation in response.
- It remains uncertain whether thrombosis occurs as part of a primary thrombotic process or as an end-point of a profound inflammatory state.
- Bleeding appears to be uncommon in COVID-19 patients.
- Lymphopenia is the most common laboratory finding but is not sensitive or specific.
- Elevation in D-dimer has been observed in COVID-19, particularly in critically ill patients.
- It’s unclear if elevated D-dimer reflects hypercoagulability or underlying inflammatory state or both.
- Thrombocytopenia is not marked, though lower platelet count may be associated with increased critical illness and mortality.
- We recommend thromboprophylaxis with weight-adjusted low molecular weight heparin (LMWH) in all hospitalized COVID-19+ or COVID-19 suspected patients in the absence of contraindications (e.g. active bleeding, platelet count less than 25)
- We recommend intermittent pneumatic compression devices if pharmacological thromboprophylaxis is contraindicated.
- If using intermittent pneumatic compression devices, we recommend a daily assessment of suitability to initiate pharmacologic thromboprophylaxis.
- We do not recommend higher dose thromboprophylaxis unless part of a clinical trial.
- We do not recommend initiation of antiplatelet agents for thromboprophylaxis in COVID-19 patients unless part of a clinical trial.
- We recommend the use of LMWH for critically ill patients requiring therapeutic anticoagulation.
- The use of LMWH in patients with impaired renal function may require monitoring of anti-Xa levels. We recommend consultation with an ICU pharmacist.
- Therapeutic anticoagulation is recommended for known evidence-based indications (e.g. venous thromboembolism, mechanical prosthetic heart valves, atrial fibrillation) in the absence of contraindications.
- Critically ill COVID-19 patients on therapeutic anticoagulation with direct oral anticoagulants or warfarin should be switched to therapeutic subcutaneous LMWH, if possible.
- We recommend against routine initiation of therapeutic anticoagulation outside of usual evidence-based indications unless part of a clinical trial.
- We recommend against the use of thrombolytic drugs (tPA) in COVID-19 patients outside of usual evidence-based indications unless part of a clinical trial.
Venous Thromboembolism (VTE)
- There may be higher VTE rates in critically ill COVID-19 patients despite pharmacological thromboprophylaxis although this data is unconfirmed
- For suspected deep vein thrombosis (DVT), obtain a Doppler ultrasound to confirm.
- For suspected pulmonary embolism (PE), obtain CTPA to confirm
- If unable to obtain CTPA, consider leg dopplers.
- If unable to confirm diagnosis and suspicion for PE remains high, suggest therapeutic anticoagulation in the absence of contraindications.
Anticoagulation in Hemodialysis
- Global and local experience suggests dialysis circuit clotting is more frequent in COVID-19 patients compared to other critically ill patients with AKI requiring RRT
- We do not recommend the therapeutic anticoagulation of all patients with AKI and COVID-19 outside of clinical trials.
- For AKI requiring RRT, we recommend patient-specific consideration for therapeutic anticoagulation as not all patients will require systemic anticoagulation.
- A higher proportion of COVID-19 patients are expected to require anticoagulation to reduce dialysis circuit clotting compared to other non-COVID critically ill patients.
- If there is evidence of dialysis circuit clotting, or clotting is expected based COVID-19+ and renal failure, initiate therapeutic anticoagulation prior to initiation of dialysis if there are no contra-indications
- We recommend low molecular weight heparin (dalteparin or tinzaparin) given subcutaneously rather than unfractionated heparin infusion for therapeutic anticoagulation
- We recommend dalteparin 100 units/kg subcutaneously BID (or equivalent tinzaparin) with no weight maximum
- LMWH has several advantages over unfractionated heparin
- Subcutaneous delivery – conservation of tubing, infusion pump availability
- More predictable, controlled level of anti-coagulation
- No routine PTT monitoring is required, and PTT may be less reliable in COVID-19 critically ill patients
- Lower risk of HITT
- We recommend sending anti-Xa levels on day 5 of LMWH therapy and appropriate dose adjustment made in consultation with ICU pharmacist