Pulmonary embolism and DVT Flashcards Preview

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Flashcards in Pulmonary embolism and DVT Deck (70):



How do DVTs occur?


Starts with damage to the endothelium, which causes vasoconstriction and subsequent platelet activation (primary haemostasis) and of clotting factors (secondary haemostasis), which forms a fibrin plug




What are risk factors for the development of DVT?

  • Trauma
  • Hormones - COCP, pregnancy
  • Road traffic accidents
  • Operations
  • Malignancy
  • Blood disorder - polycythaemia etc.
  • Old age, obesity
  • Serious illness
  • Immobilisation
  • S plenectomy

Others include dehydration and previous DVT




What are signs of DVT?


  • Calf warmth
  • Swelling
  • Tenderness
  • Erythema
  • Pitting oedema




What are symptoms of DVT?

Can be asymptomatic

If symptomatic

  • Leg swelling
  • Calf tenderness
  • Persistent discomfort




What type of clot is a DVT?



Red clot - rich in fibrin and trapped erythrocytes (hence redness)


Important to remember for treatment - red clots are treated using heparins and warfarin, as they target fibrin production




If someone presented with suspected DVT, what is important to do when examining the leg?



Look at colour, feel warmth, feel for pulses, and MEASURE CALF CIRCUMFERENCE




How would you determine what investigations to do on someone presenting with DVT?



Wells Score for DVT to assess risk




If someone presented with features of a DVT, what else would be part of a differential diagnosis?


  • Cellulitis
  • Ruptured baker's cyst
  • Tumour
  • Calf muscle haematoma
  • Necrotising fasciitis - if really acute




How would distinguish a DVT from cellulitis?


Usually manifest redness, heat, and swelling in the dermis of the affected leg.

The affected area is likely to be smaller than in DVT (which may involve the entire foot, calf, or thigh), but the signs more pronounced.




What criteria are assessed in the DVT Wells score?


  • Active cancer = +1
  • Paralysis/plaster = +1
  • Bed >3 days/surgery within 4 weeks = +1
  • Tender veins = +1
  • Entire leg swelling = +1
  • Calf swelling >3 cm = +1
  • Pitting oedema = +1
  • Collateral veins = +1
  • Alternative diagnosis likely = -2




What does a DVT Wells score of =0 mean?



DVT unlikely




What does a DVT wells score of 1-2 indicate?



DVT moderately likely




What does a DVT wells score of >2 indicate?



DVT highly likely




What investigations would you do if someone had a Wells score of <2?



  • D-dimer




What investigations would you do in someone with DVT Wells score of >2?



D-dimer and Doppler ultrasound




What are important questions to ask in someone with swollen legs (9 questions...)?

  1. Is it both legs?
  2. Any trauma?
  3. Any pain
  4. Is she Pregnant?
  5. Any Pitting?
  6. Any skin changes?
  7. Are they Mobile?
  8. PMH/Medical History?
  9. Any oedema elsewhere?




If someone presented with swollen legs, what oedematous conditions would you consider?


  • Nephrotic syndrome
  • CCF




What does bilateral leg swelling indicate?



Implies systemic disease with increased venous pressure or decreased intravascular oncotic pressure




What are causes of bilateral leg swelling?


  • Right heart failure
  • Renal/liver failure
  • Venous insufficiency
  • Vasodilators - nifedipine, amlodipine
  • Pelvic mass
  • Pregnancy




How would you managet someone with a DVT?


Early mobilisation

Adequate hydration


  • LMWH
  • Introduce Warfarin - switch to just warfarin when INR 2-3


  • Inferior vena caval filter




How long would you treat someone with a DVT with warfarin which was caused by a surgical procedure?



3 months




How long would you treat someone with warfarin for a DVT if no cause of DVT was found?



6 months




How long would you treat someone with warfarin for DVT if they had recurrent DVT?







What measures could you take to prevent DVT from developing?


  • Stop the pill 4 weeks pre-op
  • Mobilisation
  • Prophylactic LMWH
  • Compression stockings
  • Intermittent pneumatic compression devices - those that are immobile




What are complications of a DVT?


  • Pulmonary embolism
  • Stroke - if ASD present
  • Post-phlebitic syndrome
  • Bleeding complications from treatment




What is the mechanism behind dyspnoea in thromboembolism?


It is thought that pressure receptors or C-fibres in the pulmonary vasculature or right atrium are activated and interact with central systems, contributing to dyspnoea




If you found a DVT on investigation, what other investigation might you do?

Look for causes

  • Thrombophilia testing
  • Underlying malignancy - Urine dip, FBC, LFT, Ca2+, CXR +/- CT abdo/pelvis if >40




What is a pulmonary embolism?



A venous thrombi, usually from a DVT, passes into the pulmonary ciruclation and blocks flow to the lungs




In a PE, which physiological process occurs (alveolar dead space or shunting) and what would be the V/Q ratio (>1)?



Alveolar dead space - V/Q mismatch >1




What are risk factors for PE?

  • Trauma
  • Hormones - COCP, pregnancy
  • Road traffic accidents
  • Operations
  • Malignancy
  • Blood disorder - polycythaemia etc.
  • Old age, obesity
  • Serious illness
  • Immobilisation
  • Splenectomy

Others include dehydration and previous DVT




What symptoms might you see in someone with a PE?

Sudden onset

  • Dyspnoea - can be severe
  • Cough +/- haemoptysis
  • Pleuritic chest pain
  • Syncope




Why can haemoptysis occur in PE?


Any condition that results in pulmonary venous hypertension may cause haemoptysis. For example, left ventricular failure can lead to increasingly high pulmonary venous pressures. These high pressures damage venous walls, causing blood excursion into the lung and eventually haemoptysis.




Why might you get raised JVP in PE?



PE may be large enough to create back pressure into the right heart, atrium and venous system, thus resulting in




Why might you get a pleural rub in PE?



Inflammatory process is triggered by emboli, which spreads into the plerua and causes loss of normal pleural lubrication




Why does tachycardia occur in PE?



Activation of the sympathetic nervous system and/or catecholamine release due to a combination of hypoxia and reduced stroke volume and resultant CO (heart tries to compensate)




Why does hypotension occur in PE?



Reduced SV, therefore reduced CO - heart tries to compensate




Why can those with PE develop a gallop rhythm?



Due to heart failure caused by PE - rapid ventricular against stiff ventricular walls causes the sound




Why would you get a loud P2 in PE?



Increased PHT of any cause causes the pulmonary valve to slam shutand cause a louder than normal P2




Why would you get right ventricular heave in PE?







What might you see on ECG in someone with a PE?


  • Sinus Tachycardia
  • RV strain - T-wave inversion V1 to V4 and inferior leads, RBBB, right axis deviation
  • RA enlargement - P pulmonale, RV dilation i.e. dominant R in V1
  • S1Q3T3 pattern - rare




What might you see on X-ray in PE?


  • Hampton Hump - Wedge infarcts
  • Westermarks signs - Regional oligaemia
  • Fleischer's Sign - Enlarged pulmonary artery
  • Elevated hemidiaphragm
  • Effusions




What are the criteria for the PE Wells Score?


  • Clinical signs and symptoms of DVT = +3
  • Alternative diagnosis less likely = +3
  • HR >100 = +1.5
  • Immobilisation (>3/7days) / surgery in the past month = +1.5
  • Previous DVT/PE = +1.5
  • Haemoptysis = +1
  • Cancer - on treatment, past 6 months or palliative = +1




What causes tachypnoea in PE?



Compensatory response to either a drop in O2 or a rise in CO2




Why might you get central cyanosis in someone with PE?


A V/Q mismatch or shunting of blood through the lungs, without adequate oxygenation, will increase the quantity of deoxygenated haemoglobin that passes out of the lungs, leading to reduced oxygen saturation




What signs might you see in someone with a a mild PE?


  • Tachycardia
  • Tachypnoea
  • Decreased SpO2
  • Pleural Rub
  • Mild fever




How would you approach investigating someone with a PE?

Decide if non-massive or massive. If non-massive - Wells score, then:

  • Confirm diagnosis
  • Determine severity
  • Look for causes




How would you confirm/Exclude the diagnosis of PE?


  • Low Wells score - D-Dimer - if negative exclude
  • High Wells score or D-dimer positive - CTPA or V/Q (if CTPA contraindicated)




How would you investigate the severity of a PE?


  • Clinical Signs
  • Bloods - ABG's, FBC, U+E's
  • ECG
  • CXR
  • Echocardiogram
  • Bilateral leg Doppler (look for DVTs)




What signs might you see in someone with a severe PE?

  • Decreased SpO2
  • Tachycardia
  • Tachypnoea
  • Hypotension
  • Raised JVP with prominent a wave
  • Gallop rhythm
  • Pleural rub
  • Loud P2 and splitting of S2
  • Tricuspid/pulmonary regurgitation
  • Right venticular heave
  • Cyanosis




If you suspected a massive PE, how would you investigate?



CTPA or Bedside Echo

Move to HDU




What would you do if someone with a suspected non-massive PE had a Wells score <4?



  • Negative - excluded
  • Positive - CXR (determine if normal or abnormal)/Consider need for immediate CTPA




What would you do if someone with a suspected non-massive PE had a Wells score of >4?



Perform CXR - determine if normal or abnormal




If someone with suspected non-massive PE had a normal CXR, what would you do?


Determine PESI score

  • <86 - Discharge to AEC
  • 87-124 - Send for V/Q Scan
  • >125 - Consider HDU




If someone with suspected non-massive PE had an abnormal CXR, what would you do?


Determine PESI score

  • <86 - Discharge to AEC
  • 87-124 - Send for CTPA
  • >125 - Consider HDU




What investigations might you do to look for the causes of PE?


  • USS - Legs, abdo and pelvis
  • CT - Abdo/pelvis
  • Inherited coagulopathy screen
  • Autoimmune screen




What is the gold standard investigation for PE?



CT pulmonary angiography




When would you start LMWH in someone with a suspected PE?



If theare deemed high risk, start before CTPA - START BEFORE CONFIRMATION




When would you start warfarin in someone with a suspected PE?



After PE has been confirmed




What dose of LMWH would you start someone on with a suspected PE?







How would you manage someone with a PE?


  • O2 therapy
  • LMWH (when suspected), then switch to warfarin (when confirmed)
  • Analgesia
  • IV fluids - if hypotensive
  • Consider thrombolysis




When would you consider thormbolysis in someone with a PE?



  • Haemodynamic instability - systemic hypotension, Evidence of RHF
  • Cardiac arrest




What thrombolytic agents could you use for a PE?


  • Alteplase
  • Streptokinase




Why do you need to be careful when giving opiods in PE?



Can cause systemic vasodilation, worsening hypotension




What other options are available in those who thrombolysis is contraindicated in?


  • Pulmonary embolectomy
  • IVC filter




Why do those with PE become hypoxaemic and hypocapnic on ABG?


A PE causes V/Q mismatch and inflammation. Inflammation causes bronchoconstriction which causes hypoxia, leading to respiratory centres increasing respiratory drive, cause CO2 to be blown off





What would you see on ABG in someone with PE; acidosis or alkalosis?



Respiratory alkalosis




What is D-Dimer?


A fibrin degradation product (or FDP), a small protein fragment present in the blood after a blood clot is degraded by fibrinolysis. It is so named because it contains two D fragments of the fibrin protein joined by a cross-link.




Why would you not give diuretics orr vasodilators in PE?



Will cause worsening hypotension due to reduction in cardiac output and reduced TPR




Why do you give LMWH cover whilst starting somone on warfarin?


Warfarin initially decreases protein C levels faster than the coagulation factors, it can paradoxically increase the blood's tendency to coagulate when treatment is first begun (many patients when starting on warfarin are given heparin in parallel to combat this), leading to massive thrombosis with skin necrosis and gangrene of limbs. Therefore heparin is used to cover this hypercoagulable state




What additional investigations woul you consider in women over 40 with unprovoked DVT?


  • CT Abdo/Pelvis
  • Mammogram