Resp emergencies Flashcards
PE, pneumothorax, tension pneumothorax, sarcoidosis
What is pulmonary embolism?
Refers to a life-threatening condition where the formation of a blood clot in the pulmonary arterial vasculature, causing severe respiratory dysfunction.
Basically arises from a blood clot formed in the veins, e.g. DVT.
Causes of pulmonary embolism?
Venous thrombosis
Rare causes:
- right ventricular thrombus (post MI)
- septic emboli (from right-sided endocarditis)
- fat, air, or amniotic fluid embolism
- neoplastic cells
- parasites
Risk factors for pulmonary embolism?
Any cause of immboility or hypercoagulability:
- recent surgery
- recent stroke or MI
- disseminated malignancy
- thrombophilia/antiphospholipid syndrome
- pregnancy
- postpartum
- prolonged bed rest
- COCP
- HRT
How does pulmonary embolism present in a pt?
Depends on the number, size, and distribution of the emboli. Small emboli may be asymptomatic, whereas large emboli may be fatal.
Typical triad:
- Sudden-onset SOB
- Pleuritic chest pain
- Haemoptysis
Cough
Syncope
Tachypnoea
Tachycardia
Hypoxia
Low-grade pyrexia (fever)
Hypotension
Cyanosis
Pleural rub
Pleural effusion
Scars from recent surgery
Signs of right heart strain
- raised JVP
-parasternal heave
- loud P2
Signs of DVT
- unilateral swollen calf/leg
- tender calf
- vein distention
- erythema
- warm to touch
What is PERC score?
Rules out pulmonary embolism if none of the factors below are identified. If one factor is a ‘YES’, then you can’t rule out PE.
Low risk →no further diagnostic testing required → pt can be safely discharged or investigate other underlying cause
Score out of 8.
- age ≥50 (1)
- HR ≥100 (1)
- O2 sat <95% (1)
- unilateral leg swelling (1)
- haemoptysis (1)
- recent surgery or trauma (1)
- prior PE or DVT (1)
- hormone use (1)
What is Wells’ criteria for pulmonary embolism?
Risk stratifying pts with a suspected PE.
Total score 12.5.
If Well’s score is ≤4:
- D-dimer
- low D-dimer rules out PE
- if it raised, do CTPA or V/Q scan
If Well’s score >4:
- CTPA
- If CTPA -ve, suspect DVT do US doppler
- clinical signs and symptoms of DVT (3)
- PE is #1 diagnosis OR equally likely (3)
- HR >100 (1.5)
- immbolisation at least 3 days OR surgery in the last 4 wks (1.5)
- haemoptysis (1)
- prior PE or DVT (1.5)
- malignancy with tx within 6 months or palliative (1)
Investigations pulmonary embolism (PE)?
ECG
- normal or sinus tachycardia
- massive PE: right heart strain (P pulmonale, right axis deviation, RBBB, non-specific ST/T wave changes)
- classic rare S1Q3T3 (deep S waves in lead I, pathological Q waves in lead III and inverted T waves in lead III)
CXR
- signs of pneumothorax and pneumonia
- Fleischner sign (enlarged pulmonary artery)
- Hampton’s hump (a peripheral wedge shaped opacity)
- Westermark sign (regional oligaemia)
CTPA (CT pulmonary angiogram)
- diagnostic test of choice for PE
- very sensitive
- will show a filling defect in the pulmonary vasculature
V/Q scan (ventilation/perfusion) – preferred if the patient has renal impairment, contrast allergy or is pregnant
Lower limb Duplex
– helpful if a DVT is thought to be the cause of the PE
- this IVx is first-line – before a CTPA – in pregnancy
Bloods:
- D-dimer (raised if lysis of cross-linked fibrin within the thrombus)
- FBC
- CRP
- U&E
- Clotting function
-ABG (type 1 respiratory failure and/or a respiratory alkalosis)
What is D-dimer? When is D-dimer helpful?
Breakdown product of cross-linked fibrin by the fibrinolytic system.
Raised D-dimer -if lysis of cross-linked fibrin within the thrombus.
If D-dimer is low in pts who have low probability of PE, then you can be reassured that pt is unlikely to have PE.
Very high D-dimer levels should increase suspicion of PE, but not diagnostic.
When is D-dimer worthless?
- Recent surgery or trauma
- Patient has other auto-immune or
inflammatory process going on in
the body - Liver / Renal / Heart Failure
- Pregnancy
- Sepsis
- Sickle cell disease
- Acute MI or Stroke
How is suspected pulmonary embolism managed?
Immediate hospital admission if suspect PE in pts with:
haemodynamic instability:
- cardiac arrest
- obstructive shock (systolic BP <90 mmHg, end-organ hypoperfusion)
- persistent hypotension
pregnant or have given birth within the past 6 wks
Wells score >4
- hospital admission for immediate CTPA, if not offer interim anticoagulation
Wells score <4
- D-dimer test within 4 hrs, if not offer interim anticoagulation
- +ve D-dimer = CTPA, or interim anticoagulation
- -ve D-dimer = stop interim anticoagulation, alternative diagnosis
Before starting on interim anticoagulation, do baseline blood tests (FBC, renal, liver, prothrombin time, activated partial thromboplastin time).
How is confirmed pulmonary embolism (PE) managed?
Anticoagulant tx (DOAC -rivaroxaban or apixaban or dabigatran)
Thrombolysis (breaks down clots)
Embolectomy (if thrombolysis is contraindicated)
Inferior vena cava (IVC) filters
- if pt has recurrent DVTs despite anticoagulation or if anticoagulation is contraindicated
What is pneumothorax?
Refers to the presence of air within the pleural space and the subsequent collapse of the lung.
How are the causes classified? Give examples.
Spontaneous
* Primary (no underlying lung pathology)
- typically tall thin young men
- secondary (underlying lung pathology)
- obstructive (asthma/COPD)
- infective (TB and pneumonia)
- fibrotic (cystic fibrosis and idiopathic pulmonary fibrosis)
- neoplastic disease (bronchial carcinoma)
- connective tissue disease (Marfan’s syndrome and Ehlers-Danlos syndrome)
Trauma
- iatrogenic
- non-iatrogenic (either a penetrating trauma or blunt trauma with rib fracture)
Presentation of pneumothorax?
sudden-onset SOB
pleuritic chest pain
tachypnoeic
respiratory distress
On the affected side:
- reduced or absent chest expansion
- hyper-resonant percussion note
- diminished or absent breath sounds (no added sounds)
- vocal resonance (or tactile vocal fremitus) is reduced
- tinkling crepitations when fluid present
Opposite the affected side:
- mediastinal displacement
Tension pneumothorax include:
- signs of haemodynamic compromise (tachycardia and hypotension)
- tracheal deviation to the opposite side.
Investigations for pneumothorax?
CXR
- assess degree of collapse (small is <2cm rim of air around the lung; large is >2cm)
