Pulmonary embolism Flashcards
What is PE?
This is a life-threatening condition resulting from dislodged thrombi; occluding the pulmonary vasculature.
Right heart failure and cardiac arrest may occur.
Aetiology of PE
About 50% of DVT will embolise to the pulmonary vasculature, resulting in a PE.
Virchow’s triad.
Pathophysiology of PE
Thrombi rarely develop de novo in the pulmonary vasculature.
PE is closely related to DVT.
An embolus is some material (air bubble, clot) which is transported in the bloodstream and lodges in a blood vessel at a different site.
Obstruction increases pulmonary vascular resistance (PVR) increasing the work of the right ventricle. This compensates by increasing HR.
Decreased RV output progresses to hypotension and shock.
Signs and symptoms of PE
Sudden-onset pleuritic chest pain Dyspnoea Haemoptysis and syncope are less common. Increased RR Tachyarrythmias Possibly signs of DVT
Investigations for PE
Wells score
D-dimer
CTPA (diagnostic)
V/Q lung scan
Differentials of PE
Angina (unstable) MI Pneumonia Acute bronchitis COPD flare up Asthma flare up CHF Pericarditis Cardiac tamponade Pneumothorax Pulmonary HTN Panic disorder
Management of PE in an acute setting
-Assess for signs of shock or hypotension (ABCDE approach), which can indicate a high-risk (massive/central) PE.
-A high-risk PE is defined as a systolic blood pressure (SBP) <90 mmHg or a SBP drop by ≥40 mmHg for >15 minutes, if not caused by a new-onset arrhythmia, hypovolaemia, or sepsis.
-Signs of shock include altered cognition, cool extremities, mottled or ashen skin, slow capillary refill, and oliguria.
If the patient is in peri-arrest/cardiac arrest and PE is suspected it is common practice to give thrombolysis immediately without waiting for results of investigations.
-Give intravenous fluids if SBP <90 mmHg or there are other signs of shock:
Give either normal saline or Hartmann’s; start with a 500 mL fluid challenge.
Monitor for signs of heart failure:
The leading cause of death in patients with high-risk PE is acute right ventricular (RV) failure with resulting hypotension.
-Ensure early respiratory support:
Titrate oxygen to 94% to 98%(or 88% to 92% in patients at risk of hypercapnic respiratory failure).
Use mechanical ventilation if necessary. Beware that this can worsen hypotension so monitor blood pressure closely.
Arrange emergency primary reperfusion for any patient with shock or hypotension.
-Systemic thrombolysis is the standard treatment of choice.
Do not allow supportive therapy to delay thrombolysis, which may quickly restore haemodynamic stability.
Use vasoactive drugs if SBP remains <90 mmHg after thrombolysis and adequate fluid resuscitation.
-Give anticoagulation early if indicated:
Check the patient has no contraindications to anticoagulation.
You do not need to wait for the results of investigations to give anticoagulation if PE is highly suspected.
Be aware of special cases such as pregnancy, renal impairment, and active cancer as these groups will need a specific type/dose of anticoagulant.
Treatment of PE
Anticoagulation can usually be stopped after 3 months following a provoked PE.
-A provoked PE is one associated with a transient risk factor that was present in the 3 months prior to the PE.
Transient provoking risk factors include surgery; trauma; significant immobility (bedbound, unable to walk unaided, or likely to spend a substantial proportion of the day in bed or in a chair); pregnancy or puerperium; use of oral contraceptive/ hormone replacement therapy.
Treatment for longer than 3 months is generally not recommended following a provoked PE, provided that the transient risk factor no longer exists.
Unprovoked PE
Anticoagulation is typically continued for >3 months after an unprovoked PE.
An unprovoked PE is a PE in a patient who either:
Did NOT have a transient risk factor (as listed above) in the 3 months prior to the PEOR
Has a provoking risk factor that persists (such as active cancer, thrombophilia, obesity).
Complications of PE
Acute bleeding during treatment Pulmonary infarction Cardiac arrest/death HIT Recurring VTE
What is a massive PE?
This is a large clot which lodges in the right side of the heart, or in both pulmonary arteries.
It classically presents with syncope.
Massive PE is diagnosed by presence of systolic pressure (<100 mmHg) or cardiogenic shock.
It is a medical emergency and requires urgent thrombolysis.
What is VTE prophylaxis?
PE remains leading cause of preventable in-hospital deaths.
VTE prophylaxis consists of pharmacological and non-pharmacological measures to diminish risk of DVT and PE.
Risks of VTE
Previous VTE Thrombophilia Malignancy Postoperative setting Trauma Indwelling central catheter Chronic medical conditions Increasing age Obesity
Treatment for VTE prophylaxis?
Early mobilisation
Graduated compression stockings
Intermittent pneumatic compression devices
LMWH or UFH
