EM Trauma 18: Pulmonary Flashcards
Remarks on penetrating chest injuries
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
Remarks on thoracic trauma
In polytrauma patients, thoracic trauma is the 3rd leading cause of death after abdominal trauma and head trauma.
Breath sounds are most readily heard in the
Axillae
Remarks on rib fractures
Localized and consistent tenderness over ribs should be attributed to rib fractures, even in the absence of findings on conventional chest radiography
Remarks on physical exam findings for pneumothorax
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
Specific pulmonary injuries
- Pulmonary contusion
- Hemothorax
- Pneumothorax
- Pneumomediastinum
- Pulmonary hematoma
- Pulmonary laceration with hemopneumothorax
- Aspiration
Pulmonary contusion is defined as
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
The most common cause of pulmonary contusion
compression-decompression injury to the chest,
such as seen in high-speed motor vehicular crashes
2 stages of pulmonary contusion
- Direct injury to lung parenchyma
- Cardiopulmonary decompensation (from IV fluid resuscitation)
Diagnosing pulmonary contusion
- Chest pain, tachypnea, chest wall contusions, and hypoxia suggest underlying pulmonary contusion
- Areas of lung opacification on chest imaging within 6 hours of blunt trauma are usually considered diagnostic of pulmonary contusion
- 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
Pulmonary contusion and ARDS
Patients who have a contusion >20% of lung volume have up to an 80% risk of developing ARDS
Treatment of pulmonary contusion
- Maintenance of adequate ventilationed
- aggressive chest physiotherapy
- obligatory mech vent should be avoid - Pain control
- Avoidance of unnecessary fluid administration
- Steroids should not be used for pulmonary contusions
Preferred method of pain control for pulmonary contusions
Epidural analgesia
however, consider intercostal nerve blocks and paravertebral analgesia when an epidural is conraindicated
Most common cause of hemothorax
Bleeding from direct lung injury
Remarks on hemothorax
- If the hemothorax is juddged large enough to drain (>200 to 300 mL), tube thoracostomy remains the standard of care
- Fluid colletions >200 to 300 mL can usually be seen on upright or decubitus chest radiographs
- Large clots in the pleural space can act as a local anticoagulant by releasing fibrinolysins from their surface
- Bleeding from multiple small intrathoracic vessels often stops fairly rapidly after the hemothorax is completely evacuated
When to consider surgical exploration in hemothorax?
> 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
Common causes of massive hemothorax
injury to the lung parenchyma,
intercostal arteries,
or internal mammary arteries
A massive hemothorax is life-threatening by what 3 mechanisms?
- Decreased preload from acute hypovolemia
- Hypoxia from alveolar hypoventilation, ventilation-perfusion mismatch, anatomic shunting from collapsed lung
- Further decrease in preload and increased pulmonary vascular resistance (PVR) from hydrostatic pressure exerted by the massive hemothorax
Absence of lung sliding is not 100% specific for pneumothorax as it can also be seen in
large pulmonary contusions
incorrect endotracheal tube placement
Remarks on occult pneumothoraces
Intubation and positive-pressure ventilation may convert a small occult pneumothorax into a tension pneumothorax
Pneumothorax after a stab wound may be delayed for up to
6 hours
Consequently, repeat chest imaging in 4 to 6 hours is indicated in these patients or at any time when symptoms worsen
Remarks on tension pneumothorax
- Diagnose and treat tension pneumothorax clinically, before the chest radioraphy is obtained
- 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
- 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.
Causes for failure of complete lung expansion or evacuation of a pneumothorax
- Improper connections or leaks in the external tubing or water-seal colleciotn apparatus
- Improper positioning of the chest tube
- Occlusion of bronchi or bronchioles by secretions or foreign body
- Tear of one of the large bronchi
- Large tear of the lung parenchyma
Management of an open pneumothorax
- Cover the wound with a three-sided dressing
- Avoid complete occlusion, as this may convert the injury into a tension pneumothorax
- 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
