PE Flashcards
define PE, DVT, VTE
Pulmonary embolus (PE) occurs when a clot from a vein, originating in the venous sinuses of the calf or the femoral vein or the pelvis, detaches and becomes lodged in the pulmonary arterial tree
Occasionally the right side of the heart is a source of a pulmonary embolus.
Deep vein thrombosis (DVT) is the formation of blood clots in deep veins of the legs. In a majority of patients, PE is a consequence of DVT
when sensitive diagnostic methods were used, DVT was detected in around 70% of patients with PE
clinically important PEs originate from proximal DVT of the leg e.g. - popliteal, femoral or iliac veins
Venous thromboembolism (VTE) is the term used to describe a thrombus in a vein which may detach from the site of origin and travel through blood to a distant site, a phenomenon called embolism. PE and DVT represent different clinical manifestations of VTE
Non thrombotic pulmonary emboli are rare. Causes include:
- septic emboli
- fat emboli
- amniotic fluid
- venous air embolism
- intravascular foreign bodies
- tumor emboli
RFs
Risk Factors: SPASMODICAL
Sex: F
Pregnancy
Age: ↑
Surgery (classically 10d post-op straining at stool)
Malignancy
Oestrogen: OCP/HRT
DVT/PE previous Hx
Immobility
Colossal size
Antiphospholipid Abs
Lupus Anti-coagulant
s/s
symptoms:
- chest pain: typically pleuritic
- dyspnoea
- haemoptysis
- syncope
signs:
- tachycardia
- tachypnoea
- fever
- cyanosis
- RHF: hypotension, high JVP, loud P2
- evidence of cause: DVT
never always presents as textbook pic in real life
factors that make PE more likely:
- Tachypnea (respiratory rate >16/min) - 96%
- Crackles - 58%
- Tachycardia (heart rate >100/min) - 44%
- Fever (temperature >37.8°C) - 43%
ix of PE
All patients with symptoms or signs suggestive of a PE should have a history taken, examination performed and a chest x-ray to exclude other pathology.
If a PE is still suspected a two-level PE Wells score should be performed:
- Clinical signs and symptoms of DVT (minimum of leg swelling and pain with palpation of the deep veins) = 3
- An alternative diagnosis is less likely than PE = 3
- Heart rate > 100 beats per minute= 1.5
- Immobilisation for more than 3 days or surgery in the previous 4 weeks = 1.5
- Previous DVT/PE = 1.5
- Haemoptysis = 1
- Malignancy (on treatment, treated in the last 6 months, or palliative) = 1
Clinical probability simplified scores
- PE likely - more than 4 points
- PE unlikely - 4 points or less
If a PE is ‘likely’ (more than 4 points) arrange an immediate computed tomography pulmonary angiogram (CTPA). If there is a delay in getting the CTPA then give LMWH until the scan is performed.
- if the CTPA is negative then patients do not need further investigations or treatment for PE
- if postive - treat!!
If a PE is ‘unlikely’ (4 points or less) arranged a D-dimer test.
- If this is positive arrange an immediate computed tomography pulmonary angiogram (CTPA).
- If there is a delay in getting the CTPA then give LMWH until the scan is performed.
- if d-dimer is negative -> excludes PE.
If the patient has an allergy to contrast media or renal impairment a V/Q scan should be used instead of a CTPA. [but vq scan frequently gives unequivocal results]
bloods: FBC, U+E, clotting, d-dimer, increased ESR
ECG
- the classic ECG changes seen in PE are a large S wave in lead I, a large Q wave in lead III and an inverted T wave in lead III - ‘S1Q3T3’. However this change is seen in no more than 20% of patients
- right bundle branch block and right axis deviation are also associated with PE
- sinus tachycardia may also be seen
CXR: occasionally show reduced vascular markings
blood gases show impaired gas exchange with arterial hypoxaemia and hypocapnia [from hyperventilation + poor gas exchange: low pao2, low paco2, high pH
mx- start asap, most PE deaths occur w/i 1 hour
oxygen if hypoxic, 10-15 L per min
morphine 5-10 mg iv with anti-emetic if pt is in pain/v distressed
iv access + start LMWH/fondaparineux
if low BP give 500mL IV fluid bolus + get ICU input
haemodynamically unstable??
- yes- consider thrombolysis [eg. alteplase 10mg iv bolus then IVI] thrombolysis is now recommended as the first-line treatment for massive PE where there is circulatory failure (e.g. hypotension).
- no-
- if sbp > 90- start wardarin- must give w/i 24 hrs of diagnosis
- is sbp persistently <90 consider vasopressors eg. dobutamine IV + consider adding noradrenaline= aim for SBP >90mmHg
nb::::::::::::: vitamin K antagonist (i.e. warfarin) should be given within 24 hours of the diagnosis [ An exception to this is for patients with a massive PE where thrombolysis is being considered. In such a situation unfractionated heparin should be used.
now give TEDS
+ WEAR TEDS STOCKINGS IN HOSPITAL
+ MAY GIVE GRADUATED COMPRESSION STOCKINGS FOR 2 YRS IF DVT: to prevent post-phlebitic syndrome
and initiate long term anticoagulation:
- the LMWH or fondaparinux should be continued for at least 5 days or until the international normalised ratio (INR) is 2.0 or above for at least 24 hours, whichever is longer, i.e. LMWH or fondaparinux is given at the same time as warfarin until the INR is in the therapeutic range
- warfarin should be continued for at least 3 months. At 3 months, NICE advise that clinicians should ‘assess the risks and benefits of extending treatment’
- NICE advise extending warfarin beyond 3 months for patients with unprovoked PE. This essentially means that if there was no obvious cause or provoking factor (surgery, trauma, significant immobility) it may imply the patient has a tendency to thrombosis and should be given treatment longer than the norm of 3 months
- for patients with active cancer NICE recommend using LMWH for 6 months
- VC filter if repeat DVT/PE despite anticoagulation
which surgical patients are at risk of PE
- Surgery greater than 90 minutes at any site or greater than 60 minutes if the procedure involves the lower limbs or pelvis
- Acute admissions with inflammatory process involving the abdominal cavity
- Expected significant reduction in mobility
- Age over 60 years
- Known malignancy
- Thrombophilia
- Previous thrombosis
- BMI >30
- Taking hormone replacement therapy or the contraceptive pill
- Varicose veins with phlebitis
thromboprophylaxis: mechanical agents
- Early ambulation after surgery is cheap and is effective
- Compression stockings (contra -indicated in peripheral arterial disease)
- Intermittent pneumatic compression devices
- Foot impulse devices
thromboprophylaxis: pharmacological agents, list them!
Low molecular weight heparin
Binds antithrombin resulting in inhibition of factor Xa
use: In patients with normal renal function, low doses typically given in those with moderate to high risk of thromboembolic events. It is given as once daily subcutaneous injection
Unfractionated heparin
Binds antithrombin III with affects thrombin and factor Xa
use: Effective anticoagulation, administered intravenously it has a rapid onset and its therapeutic effects decline quickly on stopping and infusion. Its activity is measured using the APTT. If need be it can be reversed using protamine sulphate
Dabigatran
Orally administered direct thrombin inhibitor
- Used prophylaxis in hip and knee surgery.
- It does not require therapeutic monitoring.
- It has no known antidote and should not be used in any patient in whom there is a risk of active bleeding or imminent likelihood of surgery
chest signs seen in PE
Signs of pleural effusion, such as dullness to percussion and diminished breath sounds, may be present.
