Pulmonary Embolism

   

  • blockage of the pulmonary artery by foreign matter or by a blood clot

 

  • obstruction in the pulmonary circuit
  • embolis obstructs capillaries
  • may lead to infarction
  • 30% lethal

 

Etiology

  1. mostly from Deep Vein Thrombosis
  • majority originate in iliac veins
  • others commonly originate in popliteal or femoral veins
  1. air
  2. tumor cells
  3. fat – from marrow cavity as marrow fat enters damaged vessels
  4. vegitation on heart valves eg in endocarditis
  5. amniotic fluid – periparteum into uterine vessels

 

Pathophysiology

  • embolis depends on the size of the vessel within arterial bed
  • vessel # and size determines location
  • perfusion impaired
  • ventilation is affected
  • perfusion imbalance occurs
  • hypotension results
  • if large vessel is involved
  • increased pulmonary venous resistance
  • atelectasis

 

  • alveolar secretions – surfactant produced by group of alveolar cells
  • alveolar cells draw fluid from blood
  • damage to surfactant-producing cells
  • no surfactant is produced
  • the alveoli collapse

 

  • decreased cardiac output
  • obstruction in right side of pulmonary circuit
  • decreased volume into right atrium
  • decreases blood volume to left side of heart

 

  • platelets infiltrate embolis area
  • release of degranulators
  • inflammatory mediators act on bronchiole smooth muscle and pulmonary arteries
  • constriction causes hemodynamic instability

 

  • complication
  • Right sided heart failure
  • right side that pumps into pulmonary circuit

 

Manifestations

  • size and location dependent
  • small emboli are mostly asymptomatic

 

most common compensatory responses

  1. tachycardia
  2. increased respiratory rate
  3. dyspnea
  4. tachapnea
  5. fever – no infection – due to inflammatory response

 

Dx:

  • lung scan
  • Iodine 131 Isotope Labelled Human Serum Albumin (131 I-HSA) via IV – mildly invasive
  • pulmonary angiogram – highly invasive

 

Tx:

  • prompt recognition
  • prevent Deep Vein Thrombosis – anticoagulants and thrombolytics

Porth, C, M. and Matfin, G. 2009. Pathophysiology. Concepts of Altered Health States. 8th ed. Lippincott Williams and Wilkins.

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