EM Trauma 18: Pulmonary

Question 1

Remarks on penetrating chest injuries

Answer 1

Presume penetrating chest injuries in the “cardiac box”, an area bounded by the sternal notch, xiphoid process, and nipples, to involve the heart or great vessels until proven otherwise

Question 2

Remarks on thoracic trauma

Answer 2

In polytrauma patients, thoracic trauma is the 3rd leading cause of death after abdominal trauma and head trauma.

Question 3

Breath sounds are most readily heard in the

Answer 3

Axillae

Question 4

Remarks on rib fractures

Answer 4

Localized and consistent tenderness over ribs should be attributed to rib fractures, even in the absence of findings on conventional chest radiography

Question 5

Remarks on physical exam findings for pneumothorax

Answer 5

The sensitivity of auscultation for the detection of a traumatic hemopneumothorax is only 50%.

Subcutaneous emphysema of the chest, however, has a specificity of 98% for underlying overt or occult pneumothorax

Question 6

Specific pulmonary injuries

Answer 6

1. Pulmonary contusion
2. Hemothorax
3. Pneumothorax
4. Pneumomediastinum
5. Pulmonary hematoma
6. Pulmonary laceration with hemopneumothorax
7. Aspiration

Question 7

Pulmonary contusion is defined as

Answer 7

Direct injury to the lung resulting in both hemorrhage and edema in the absence of a pulmonary laceration.

Pulmonary contusions are a source of severe morbidity and mortality following penetrating and blunt trauma

Question 8

The most common cause of pulmonary contusion

Answer 8

compression-decompression injury to the chest,
such as seen in high-speed motor vehicular crashes

Question 9

2 stages of pulmonary contusion

Answer 9

1. Direct injury to lung parenchyma
2. Cardiopulmonary decompensation (from IV fluid resuscitation)

Question 10

Diagnosing pulmonary contusion

Answer 10

1. Chest pain, tachypnea, chest wall contusions, and hypoxia suggest underlying pulmonary contusion
2. Areas of lung opacification on chest imaging within 6 hours of blunt trauma are usually considered diagnostic of pulmonary contusion
3. CT is more sensitive for the detection of pulmonary contusions than plain radiographs, with as many as 70% of pulmonary contusions not visible on the initial radiograph

Question 11

Pulmonary contusion and ARDS

Answer 11

Patients who have a contusion >20% of lung volume have up to an 80% risk of developing ARDS

Question 12

Treatment of pulmonary contusion

Answer 12

1. Maintenance of adequate ventilationed
   - aggressive chest physiotherapy
   - obligatory mech vent should be avoid
2. Pain control
3. Avoidance of unnecessary fluid administration
4. Steroids should not be used for pulmonary contusions

Question 13

Preferred method of pain control for pulmonary contusions

Answer 13

Epidural analgesia
however, consider intercostal nerve blocks and paravertebral analgesia when an epidural is conraindicated

Question 14

Most common cause of hemothorax

Answer 14

Bleeding from direct lung injury

Question 15

Remarks on hemothorax

Answer 15

1. If the hemothorax is juddged large enough to drain (>200 to 300 mL), tube thoracostomy remains the standard of care
2. Fluid colletions >200 to 300 mL can usually be seen on upright or decubitus chest radiographs
3. Large clots in the pleural space can act as a local anticoagulant by releasing fibrinolysins from their surface
4. Bleeding from multiple small intrathoracic vessels often stops fairly rapidly after the hemothorax is completely evacuated

Question 16

When to consider surgical exploration in hemothorax?

Answer 16

> 1,500 mL of blood evacuated immediately after tube thoracostomy,
chest tube drainage of blood at 150 to 200 mL/hour for 2 to 4 hours,
or persistent blood transfusion is required to maintain hemodynamic stability

Question 17

Common causes of massive hemothorax

Answer 17

injury to the lung parenchyma,
intercostal arteries,
or internal mammary arteries

Question 18

A massive hemothorax is life-threatening by what 3 mechanisms?

Answer 18

1. Decreased preload from acute hypovolemia
2. Hypoxia from alveolar hypoventilation, ventilation-perfusion mismatch, anatomic shunting from collapsed lung
3. Further decrease in preload and increased pulmonary vascular resistance (PVR) from hydrostatic pressure exerted by the massive hemothorax

Question 19

Absence of lung sliding is not 100% specific for pneumothorax as it can also be seen in

Answer 19

large pulmonary contusions
incorrect endotracheal tube placement

Question 20

Remarks on occult pneumothoraces

Answer 20

Intubation and positive-pressure ventilation may convert a small occult pneumothorax into a tension pneumothorax

Question 21

Pneumothorax after a stab wound may be delayed for up to

Answer 21

6 hours
Consequently, repeat chest imaging in 4 to 6 hours is indicated in these patients or at any time when symptoms worsen

Question 22

Remarks on tension pneumothorax

Answer 22

1. Diagnose and treat tension pneumothorax clinically, before the chest radioraphy is obtained
2. The midclavicular approach in needling avoids the internal mammary/thoracic artery which are located approx 3 cm lateral to the sternal border and avoids mediastinal vessels
3. Patients requiring assisted ventilation with a tension pneumothorax are more likely to be hypoxic, be hypotensive, and experience cardiac arrest than those who are breathing sponaneously.

Question 23

Causes for failure of complete lung expansion or evacuation of a pneumothorax

Answer 23

1. Improper connections or leaks in the external tubing or water-seal colleciotn apparatus
2. Improper positioning of the chest tube
3. Occlusion of bronchi or bronchioles by secretions or foreign body
4. Tear of one of the large bronchi
5. Large tear of the lung parenchyma

Question 24

Management of an open pneumothorax

Answer 24

1. Cover the wound with a three-sided dressing
2. Avoid complete occlusion, as this may convert the injury into a tension pneumothorax
3. Do not insert a chest tube through the trauma wound, as it is likely to follow the missile or knife tract into the lung or diaphragm