pulmonary embolism Flashcards
Massive PE
acute PE with obstructive shock or SBP <90 mmHg (haemodynamic compromise)
Sub-massive PE
acute PE without systemic hypotension (SBP ≥90 mm Hg) (no haemodynamic compromise) but with either RV dysfunction or myocardial necrosis
Clinical features
History
May be asymptomatic SOB Pleuritic chest pain Apprehension Cough Haemotypsis Leg pain Collapse = massive PE Acute cardiovascular collapse
Clinical features
Examination
Pale, mottled skin Tachypnoea Tachycardia Signs of DVT Hypotension Altered LOC Elevated JVP Parasternal heave Loud P2 Central cyanosis
Risk Factors
Major (SLOMMP)
Surgery: (major abdominal/pelvic, hip/knee replacements, post ICU)
Lower limb problem: (#, varicose veins)
Obstetrics: ( late pregnancy, C/S, puerperium)
Malignancy: (abdominal/pelvic, advanced/metastatic)
Mobility: hospitalization, institutional care
Previous VTE
Risk Factors Minor (COM)
Cardiovascular – congenital heart disease, CHF, HT, superficial venous thrombosis, CVL
Oestrogens – OCP, HRT
Miscellaneous – COPD, neurological disability, occult malignancy, thrombotic disorder, long distance travel, obesity, other (IBD, nephrotic syndrome, dialysis, myeloproliferative disorders, paroxysmal nocturnal haemoglobinuria, Bechet’s disease)
Risk Factor (Thrombophillias)
Factor V Leiden mutation Prothrombin gene mutation Hyperhomocysteinaemia Antiphospholipid antibody syndrome Deficiency of antithrombin III, protein C or protein S High concentrations of factor VIII or XI Increased lipoprotein (a) -> test in those < 50years with recurrent or a strong FHx
Markers useful for risk stratification in acute PE
Clinical markers
Shock
Hypotension – Defined as a systolic blood pressure of <90 mmHg or a pressure drop of >40 mmHg for >15 min
Markers useful for risk stratification in acute PE
Markers of right ventricular dysfunction
RV dilatation, hypokinesis or pressure load on echocardiography
RV dilation on spiral CT
BNP or NT-proBNP elevation
Markers useful for risk stratification in acute PE
Markers of myocardial injury
Cardiac Trop T or I positive
Investigation: ECG
(Dilation of the right atrium and right ventricle with consequent shift in the position of the heart. Right ventricular ischaemia. Increased stimulation of the sympathetic nervous system due to pain, anxiety and hypoxia.) Sinus Tachycardia Q(III), S(I) deep, T(III)- inverted Non-specific ST changes Right axis deviation (that is so extreme it seems as if the heart has deviated to the left (0 and -90) P-pulmonale (Peaked P wave in lead II) Right ventricular strain pattern RBBB (complete/incomplete) Atrial tachyarrhythmias Dominant R-wave in V1
Investigation: Imaging
CXR:Rules out other pathology, focal oligaemia, wedge density (pulmonary infarction)
USS:
Point of care lower limb compression ultrasound for DVT- Should either follow or precede d-dimer testing should this be readily accessible. Treatment should start, if the point of care compression ultrasound is positive. Should the point of care ultrasound be negative, a d-dimer (if not already performed) will need to be requested and if negative, a CTPA or VQ scan ordered
CTPA:
Gold standard for evaluating PE.
The advantages of CTPA is that is fast (can be used with a single breath), accurate (sensitivity and specificity >90%) and it can diagnose other intrathoracic pathology. The disadvantages are artefact (patient movement can cause between 5-10% of CT’s to be unreadable), contrast load (requires contrast and is subject to the contraindications applicable to its usage) and radiation exposure. Calculates RV/LV ratio (>0.9) = severe
V/Q scan
Only used now when CT is contraindicated (normal scan, low, intermediate and high probability with various criteria) The result is given as a probability. Result should be used in conjunction with Pre-test probability score. Many studies are non-diagnostic. It is difficult to interpret in COPD and Asthma. V/Q scan is usually used when a patient has a contra-indication to intravenous contrast use. A good rule of thumb is to perform a chest x-ray first and to perform VQ scan only in those with a normal appearance.
ECHO:
Transthoracic ECHO and IVC assessment. PE is more likely with the following findings:
Right ventricular dilatation
Right ventricular size does not change from diastole to systole
D shaped left ventricle
Acute tricuspid regurgitation
Inferior vena cava >2.5cm and < 50% collapse
40% of patients with a PE will have right ventricular abnormalities on echo
Paradoxical septal motion towards the LV
Investigations:LABS
ABG:
D-dimer: reassuring if negative to exclude PE, use in conjunction with clinical probability
Troponin T: elevation is associated with adverse outcome even in normotensive patients, also associated with haemodynamic instability in patients with non-massive PE
BNP: if low correlates well with uneventful course
Specific Treatment
THROMBOLYSIS
tPA (alteplase)*
100mg (0.6mg/kg) over 120 minutes followed by anticoagulation
Streptokinase
1 million units over 24 hours
*Drugs of choice
Not used in non-massive or low risk PEs
Can be used up to 14 days after symptoms begin
PE resolve more quickly than with heparin alone
As successful as embolectomy in massive PE (earlier the better)
Indicated in patients with RV compromise + haemodynamically unstable
contraindications: absolute – bleeding, recent stroke, HI, current GI bleeding, relative – PUD, surgery within 7 day, prolonged CPR
If bleeds -> FFP and anti-fibrinolytics
Specific Treatment
ANTICOAGULATION
ANTICOAGULATION
Anticoagulants
Dose
Enoxaparin*
1mg/kg SC 12 hourly
Heparin
80 units/kg IV bolus, followed by 18 units/kg/hour IV infusion
*Drugs of choice
Start immediately when there is a suspicion (prior to imaging)
LMWH as good as heparin
Give straight after thrombolysis
Then needs warfarin (INR 2-3)
