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What is a pulmonary embolus

Occlusion of a portion of pulmonary artery circulation by an embolus, disrupting blood flow to lungs and decreasing gas exchange


What are the two types of pulmonary embolus?

1) Thrombotic embolus (blood clot)

2) Non-thrombotic embolus (fat, amniotic fluid, air)


Where do the majority of PE's come from?

DVT from legs (thrombotic)


Where does a thrombotic PE occlude blood flow?

From the pulmonary artery to the pulmonary vein (preventing blood from getting to lungs for gas exchange)


What are the 3 classifications of PE?

1) Massive PE
2) Submassive PE
3) Low risk PE


What is a massive PE?

Acute PE with sustained hypotension (<90mmHg or 40mmHg drop from baseline), tissue hypoperfusion, hypoxemia.

Must rule out MI before starting inotropes


How do pts die from massive PE? Heart issues or lung issues

Pts die from RV failure.

Dual blood circulation in lungs from the bronchiole + pulmonary arteries make lung infarct unlikely


What is a submassive PE?

Acute PE with stable hemodynamic status but evidence of RV dysfunction or myocardial necrosis


What is a low risk PE?

Normal BP, no RV dysfunction or signs of MI


What are the risk factors for PE?


1) Venous stasis
2) Hypercoagulability
3) Vessel damage


What can cause venous stasis?

Immobility, NMBAs, illness, pregnancy, AFIB, increased estrogen, obesity


What can cause hypercoagulability?

Oral contraceptives, estrogens, coag disorders


What can cause vessel damage that increases risk of PE?

Trauma, surgery, atherosclerosis, inflammation


What are the 4 things that happen (pathophys) during massive PE?

1) Increased deadspace in the affected lung (alveolar deadspace)

2) Bronchoconstriction in the affected lung (compensatory mechanism)

3) Compensatory shunting to the unaffected lung (V/Q mismatch)

4) Hemodynamic changes (pulmonary hypertension due to flow obstruction)
--> Mediators released at site of clot causes pulmonary vasoconstriction


Why do the lungs bronchoconstrict during massive PE?

Low perfusion to the lung means low CO2 is carried up to alveoli. Compensatory bronchoconstriction kicks in to help pt retain CO2 as body thinks serum CO2 is low


What are the causes of RV failure as a result of massive PE?

1) Flow obstruction in pulmonary artery causes pulmonary hypertension

2) Increased workload for RV due to increased afterload

3) Decreased preload at the L ventricle decreases CO and BP

4) Too much blood backs up into RV, not enough O2, RV dilates, cells die


What is the effect of the mediators released from the PE clot?

Pulmonary vasoconstriction from the clot mediators on top of compensatory pulmonary vasoconstriction in hypoxemia makes hypoxia and pulmonary hypertension worse


How is PE diagnosed?

Spiral CT with contrast

Required for definitive diagnosis: Pulmonary angiography, V/Q scan (cannot do if vented)

CXR, echocardiogram (assess RV)

Doppler (Assess DVT)



What are ABG changes associated with massive PE/

Initially resp alkalosis then combined acidosis from anaerobic metabolism and resp failure


What are assessment findings related with massive PE?

Resp distress, pleuritic chest pain, cough, signs of DVT, distended neck veins, ventricular arrythmias, tachycardia, crackles, decreased breath sounds


What is medical management for PE?

Ventilation, hemodynamic management, anticoags, thrombolytic agents (only for massive PE, best given within 48hrs)

Catheter directed treatment, surgical embolectomy, IVC filter


What is a pneumothorax?

Accumulation of BLOOD or AIR in the pleural space


What are the 3 types of pneumothorax?

1) Open pneumo
2) Closed pneumo
3) Tension pneumo


What is an open pneumo and what can cause it?

Opening in the pleural cavity by laceration to chest wall or parietal pleura. Air enters the space.

Can be caused by trauma, central line insertion, rib fractures


What is a closed pneumo and what can cause it?

No disruption to parietal pleura but visceral pleura is torn

Can be caused by alveolar rupture, blunt chest wall trauma, pneumonia, emphysema "blebs"


What is a tension pneumothorax and what can cause it?

Air enters pleural space on inspiration but cannot exit on expiration. More air builds up and causes lung collapse and mediastinal shift.

Can be caused by both open and closed pneumo


Why is mediastinal shift bad?

Compresses the heart and other lung will also collapse


What is pathophys for open or closed pneumo?

1) Air enters pleural space
2) Affected lung compressed, collapses
3) Alveoli underventilation


What is pathophys for tension pneumo?

1) Pressure in pleural space increases
2) Affected lung collapses, causing mediastinal shift
3) Decreased preload, CO from pressure on major vessels
4) Unaffected lung also collapses


What are key assessments for pneumo?

Decreased chest expansion on affected side, resp distress, subcutaneous emphysema, tracheal deviation, hyper-resonance and decreased breath sounds on affected side