Pulmonary Embolism Flashcards
Pulmonary embolism
An obstruction of the pulmonary artery or one of its branches, caused by material (thrombus, tumor, air, or fat) which traveled from another location of the body.
Virchow’s Triad
- Hypercoagulability (cancer, thrombophilia, inflammatory disease).
- Vessel wall injury (surgery, chemical irritation, inflammation)
- Stasis of blood
Risk Factors
- pregnancy
- malignancy
- central venous catheter
- surgery
- trauma
- heart failure
- immobilization
- oral contraceptives
- hormone therapy
- congenital heart disease
- severe liver disease
- IBD
- Inherited thrombophilia (factor V, antithrombin deficiency)
Location of embolism
- Saddle (inner)
- Lobar
- Segmental
- subsegmental
- moving distally
Clinical presentation of PE
- Dyspnea on exertion or at rest
- pleuritic chest pain
- calf or thigh pain/swelling
- orthopnea
- hemoptysis
- wheezing
Signs of PE
- Tachypnea(54%)
- Edema, erythema, tenderness or a palpable cord in the calf or thigh(47%)
- Tachycardia(24%)
- Rales(18%)
- Decreased breath sounds(17%)
- Accentuated P2(15%)
- Jugular venous distention(14%)
- Fever
Lab tests
- CBC: can have leukocytosis
- ESR: elevated
- LDH: elevated
- AST: elevated
- Metabolic Panel: evaluate renal function to determine ability to give contrast
- Troponin, BNP or NT-proBNP: used for risk stratification
EKG
- Sinus tachycardia
- Nonspecific ST segment and T-wave changes
- Atrial arrhythmias
- New right bundle branch block
- S1Q3T3
Chest Xray with PE
- Usually non-specific findings
- -cardiomegaly
- -pleural effusion
- -elevated hemidiaphragm
- -pulmonary artery enlargement
- -atelectasis
- Can also be normal in up to 22% of patients
Chest CT
- Gold standard in diagnosing PE
- CT angiogram with contrast to visualize pulmonary arteries and assess for filling defect
- Contrast contraindicated in renal impairment (CrCl <30)
Ventilation perfusion scan
- Need to have “normal” chest Xray, otherwise may have false positive
- Most are read as “indeterminate”
Assessing RV
- Evaluation of right ventricular (RV) function is an important tool for risk assessment
- Screening can occur with either echocardiogram or prognostic biomarkers (troponin, BNP,) even if the PESI score is low
Initial treatment
- hemodynamic stability
- Supple O2
- IV fluids or vasopressors
- if diagnostic testing is delayed empiric anticoagulation is often initiated
Is anticoagulation appropriate?
- Determine pts bleeding risk
- absolute contraindications: hemorrhagic stroke, recent surgery, intracranial/spinal cord tumors, active bleeding
- Alternative tx: IVC filter or embolectomy
Thrombolytics
-TNKase (tenecteplase) and Retavase (reteplase)
=Reserved for hemodynamically unstable patients
-RV strain without hypotension is not an indication for thrombolytics
-“Possible” indications:
Presence of severe hypoxemia, Extensive clot burden, Free floating intracardiac clot
Contraindications for lytics: Absolute/major
Intracranial neoplasm or lesion
- Recent intracranial or spinal surgery/trauma (<2 months)
- History of hemorrhagic stroke
- Active bleeding
- Nonhemorrhagic stroke within last 3 months
- -Suspected aortic dissection
Relative contraindications for lytics
-Uncontrolled hypertension (SBP> 200, DBP >110)
-Nonhemorrhagic stroke >3 months
-Surgery within the past 3 weeks
-Pregnancy
>75 years old
-Current anticoagulation use
Alternative tx: These are considered if thrombolytics are contraindicated or has failed
- Catheter directed thrombolysis
- Surgical embolectomy
Catheter directed thromboylysis
- Thrombolytics delivered directly to pulmonary arteries
- Usually reserved for patients who remain unstable after systemic thrombolytics
- Benefit: utilizes lower dose of lytic which reduces risk of bleeding
Initial anticoagulation
- DOAC (apixaban and rivaroxaban can be used on day 1 of treatment, edoxaban and dabigatran requires 5-10 days pf bridging)
- LMWH
- UFH
Unfractionated Heparin
- Mechanism of Action: Binds to antithrombin, resulting in structural change and increase ability to inactivate factor Xa and thrombin
- Half life ½- 2 hours
- Can be used in pregnancy and renal impairment
- Reversal: Protamine
Low Molecular Weight Heparin (Lovenox)
- Same mechanism of action as UFH
- Contraindicated if creatinine clearance is <30 mL/min
- Half life approx 12 hours
- Reversal: Protamine
Heparin Induced Thrombocytopenia
-Defined as platelet count falling by ≥50%
-4 T’s Criteria (MD Calc)
-Must be confirmed by heparin antibody assay (PF4), if confirmed, list heparin as allergy
-Alternative anticoagulants should be utilized:
Argatroban, bivalrudin, fondaparinux
-If HIT is confirmed, once platelet counts have recovered (typically >50k), can initiate warfarin as there is increased risk of clotting with HIT
DOAC
- Rivaroxaban, apixaban, edoxaban, dabigatran
- Currently no generic in the US
- All DOACs have overall lower all cause mortality related to bleeding when compared to warfarin
- Apixaban and low dose edoxaban have lower GI bleeding rates compared to warfarin
DOAC MOA
- Oral direct factor Xa inhibitors include apixaban, rivaroxaban, and edoxaban and they work by preventing factor Xa from attaching prothrombin to thrombin.
- Oral direct thrombin inhibitors (dabigatran) works by preventing thrombin from attaching fibrinogen to fibrin
Pros to DOACS
- No dietary restrictions
- No monitoring
- Does not require bridging (apixaban and rivaroxaban)
- Fewer drug-drug interactions
- Lower rates of bleeding when compared to warfarin
Cons to DOACS
- Unclear dosing with obesity
- Reversal not readily available at smaller institutions
- Limited research in severe renal impairment
- Some require twice daily dosing
- Cost
DOAC drug-drug interactions: Increases DOAC blood levels
-Clarithromycin/erythromycin
-Verapamil/diltiazem
-Amiodarone
Fluconazole/ketoconazole/itraconazole
-Cyclosporine/tacrolimus
DOAC drug-drug interactions: Decreases DOAC blood levels
- Aniepileptics (Phenytoin, Phenobarbital, Carbamazepine)
- Rifampin
- St. John’s Wart
DOAC reversals: Dabigatran (Pradaxa)
-Idarucizumab (Praxbind); initial dose: 5 grams
DOAC Reversals: Apixaban (Elliquis), Betrixaban (Bevyxxa), Edoxaban (Lixiana, Savaysa), Rivaroxaban (Xarelto)
-Andexanet alfa (AndexXa) if available: initial dose depends on the dose of the factor Xa inhibitors and the interval since the last dose
OR
-4-factor PCC (Kcentra, Octapiex) if andexanet alfa is not available; initial dose 50 units per kg
Warfarin
- Mechanism of action: Blocks the conversion of inactive vitamin K to its active form within the liver resulting in non-functioning clotting factors
- Active clotting factors need to be depleted before fully anticoagulated
- Full therapeutic affect is usually achieved in 5-7 days
- Half life 12-72 hours
- Reversals: Vitamin K, FFP
Warfarin Pros
- Inexpensive
- Several reversal agents, easily accessible
- Able to monitor for compliance
- No renal restrictions
- Once daily dosing
Warfarin Cons
- Requires bridging
- Requires monitoring
- Dietary restrictions
- Higher rates of bleeding compared to DOACs
- Several drug-drug interactions
- Usually only therapeutic 65% of time
Warfarin Bridging
-When transitioning to warfarin from LMWH or UFH:
LMWH or UFH should have been used for at least 5 days
-INR should be ≥2.0 for 2 days before discontinuing LMWH or UF
-Does not require hospitalization if patient is stable
Duration of therapy
- Provoked VTE should be treated for typically 3 months
- Malignancy related PE should continue treatment while they have active cancer
- Unprovoked VTE, after 3 months should be assessed for bleeding risk, but should be considered for prolonged secondary prevention
- Consider Thrombophilia follow up for guidance on duration of therapy for special circumstances
Provoked
-Surgery with general anesthesia
-Cesarean section
-Confined to bed for at least 3 days
-Estrogen therapy
-Pregnancy
-Active cancer
-Inflammatory bowel disease
-Reduced mobility >3 days
Inheritable thrombophilia
Primary Prevention for VTE
- Heparin (5,000 units subQ every 8 hours)
- Lovenox, typical dose is 40 mg daily
IVC Filter
Used for patients who anticoagulation is contraindicated, anticoagulation has failed, or complication from anticoagulation has occurred
Treatment w/ concurrent malignancy
-Prior to 2019, recommendation for treatment of VTE in the setting of malignancy was LMWH, research has shown superior efficacy with apixaban
