Pulmonary Embolism Flashcards
What are the risk factors for PE?
(Think Virchow’s triad - venous stasis, vessel wall injury and hypercoagulability)
Same as for any VTE, e.g.:
- Prolonged immobility
- Active cancer
- Immobilisation
- > 60yrs
- Obesity
- Oestrogen medication (HRT, COCP)
- Late pregnancy
- Varicose veins, superficial thrombophlebitis
- Dehydration
- Thrombophilia
- FHx/PMHx of clotting
- Smoking
Others:
- Septic emboli from infective endocarditis
- COVID19
- (FATBAT)
What is the pathophysiology of a PE?
Clot in the pulmonary vessels, often secondary to a peripheral clot that has become embolic i.e. DVT-> PE
Provoked vs unprovoked:
- Provoked = clearly obvious cause e.g. immobile limb leading to DVT leading to PE
- Unprovoked = no clear cause, requires different management, actually more common
How does a PE present?
Chest pain = pleuritic (sharp, worse on inspiration), sudden onset
Haemoptysis, cough
Tachycardia, tachypnoea
Low grade pyrexia
Possible hypotension, jugular venous distension + Kussmaul sign (increased JV distension when inspiring) (massive PE)
Examination:
- Look for signs of DVT
- Cardioresp exam - often normal; important to exclude other causes of CP, haemoptysis etc. e.g. pneumonia, pneumothorax etc.
How do you investigate a PE acutely? What are the main findings?
ECG:
- Main finding: sinus tachycardia
- Other: right heart strain, AF, RBBB
- Rarely: S1Q3T3 (deep S waves in I and Q waves in III and TWI in III)
- Rule out cardiac chest pain
Bloods:
- D-dimer (see scoring)
- CRP - raised
- FBC - WCC/neutrophils (rule out pneumonia)
- U+E - renal function pre-CTPA
- Clotting - pre-Tx
- Troponin - to rule out cardiac cause (though can also be raised in PE)
ABG:
- Low PaO2, reduced PaCO2 due to hyperventilation or acidosis
CXR:
- Mainly to rule out pulmonary cause
- Can get pleural effusions
CT pulmonary angiography (CTPA):
- Gold standard
- A contrast scan (therefore need to consider allergies and renal function - Cr clearance <30ml/min = contraindicated)
- Will appear as darker areas against the contrast within the pulmonary arties; saddle PE = spans branching of pulmonary artery into L+R
V/Q scanning:
- Less sensitive + less information compared to CTPA but still can be used for Dx
Transthoracic echocardiogram:
- May show right heart strain
- Can be useful converging evidence if other modalities unavailable
Leg USS:
- To rule in/out DVT
What is the two-tier Well’s score for PE?
Clinical Sx of DVT - 3
PE more likely than other Dx - 3
Previous PE/DVT - 1.5
Tachycardia/HR>100 - 1.5
Surgery in the past 4 weeks OR immobilisation at least 3 days - 1.5
Haemoptysis - 1
Malignancy w/treatment within 6/12 OR palliative - 1
> 4 = PE likely, for CTPA confirmation or immediate Mx if unstable
If <4 - can use PERC/Pulmonary Embolism Rule-out Criteria to double check whether needs further Ix: (all 1 point)
- Age >50
- HR >100
- Sats <95% OA
- Unilateral leg swelling
- Haemoptysis
- Recent surgery or trauma
- Prior PE or DVT
- Hormone use
If Wells <4 and PERC >1 - D-dimer - for results in <4hrs - else give interim anticoag
How do you manage a PE acutely?
Oxygen:
- 15L on NRM if sats <92%
Pain relief:
- e.g. morphine
Fluids:
- If shocked
Antiemetics
Anticoagulation:
- (assess bleeding risk with HASBLED)
- DOAC e.g. rivaroxaban, apixaban OR Warfarin (but less so now)
- If neither appropriate - LMWH e.g. enoxaparin for 5/7 then edoxaban
- (special cases can be discussed with respiratory)
Massive PE:
- PE + hypotension/shock = thrombolysis
What long term management for PE is required?
Investigation:
- When there is no clear precipitant, we need to rule out other serious pathology e.g. Ca
- CT chest/abdo/pelvis
- Screening for antiphospholipid syndrome, hereditary thrombophilias
Anticoagulation:
- Provoked - DOAC/warfarin for 3/12, then review, if Sx improved can stop; or continue until resolved/re-evaluate for chronic PE
- Unprovoked - DOAC/warfarin for life
Other:
- Modifiable risk factor reduction
What is the PESI score?
Pulmonary Embolism Severity Index:
- Age
- Sex = M+10
- Hx Ca = +30
- Hx CCF = +10
- Hx chronic lung disease = +10
- HR >110 = +20
- SBP <100mmHg = +30
- RR >30 = +20
- Temp <36 = +20
- Altered mental state (disorientation, lethargy, coma etc) = +60
- Sats <90 = +20
Low risk <65 - can treat as outpatients
Up to: >125 = 10-25% 30 day mortality
