4.2 Thoracic Trauma, Pneumothorax & Pleural Space Emergencies

4.2 Thoracic Trauma, Pneumothorax & Pleural Space Emergencies

Clinical Scenario: A 28-year-old male arrives at the trauma bay following a rollover crash in severe respiratory distress and cyanosis. Vital signs: BP 72/40 mmHg, HR 146 bpm, RR 38, SpO2 78% on 15 L/min non-rebreather. Exam reveals absent right breath sounds, hyperresonance to percussion, distended neck veins, and tracheal deviation to the left.

Tension vs. Open Pneumothorax: Pathophysiology & Immediate Decompression

Tension Pneumothorax

Arises from parenchymal, bronchial, or chest wall tears creating a one-way valve: air enters the pleural space during inspiration but cannot exit during expiration.

1. Intrapleural Hypertension: Air accumulates, raising intrapleural pressure above atmospheric and central venous pressures.
2. Mediastinal Shift: The ipsilateral lung collapses, and positive pressure shifts mediastinal structures contralaterally, kinking the superior and inferior vena cavae.
3. Acute Obstructive Shock: Impaired venous return reduces right ventricular preload and cardiac output, producing severe hypotension, reflex tachycardia, jugular venous distention (JVD), and hypoxemia. In severe hypovolemic trauma, JVD may be absent.

Decompression Techniques

• Needle Thoracostomy: Immediate temporary bridge to tube thoracostomy:
  • Catheter Selection: Large-bore (14-gauge) catheter length $\ge 3.25$ inches (8 cm); standard 1.75-inch (4.5 cm) catheters fail in up to 50% of adults.
  • Anatomical Landmarks: Preferred ATLS site is the 4th or 5th intercostal space (ICS) at the anterior axillary line on the affected side. The alternative site is the 2nd ICS at the midclavicular line. Always insert directly over the superior margin of the lower rib to avoid the neurovascular bundle. Pressurized air release confirms decompression.
• Tube Thoracostomy: Definitive drainage. Place it promptly after needle decompression, or perform immediate definitive drainage when a trained team can do so without delay. Insert a 28–32 French chest tube for traumatic hemopneumothorax (20–24 Fr for simple pneumothorax) within the triangle of safety (bordered by pectoralis major, latissimus dorsi, apex of axilla, and 5th ICS).

Open Pneumothorax ("Sucking Chest Wound")

A full-thickness chest wall defect allows air to enter the pleural space. Larger defects can seriously impair ventilation.

• Emergency Management: Immediately apply a sterile three-sided occlusive dressing (or vented chest seal). The dressing adheres during inspiration (blocking air entry) and flutters open during expiration (venting pleural air).
• Exam Trap: An unvented seal can trap air and cause tension pneumothorax. If breathing or circulation worsens after sealing, lift or remove the seal, reassess immediately and decompress suspected tension.

Massive Hemothorax & Emergency Thoracotomy Indications

Massive hemothorax results from lacerated intercostal arteries, internal mammary arteries, or hilar vessels. Exam demonstrates dullness to percussion, diminished breath sounds, and flat neck veins.

Surgical Thoracotomy Indications

Urgently involve trauma surgery when physiology and output indicate ongoing major bleeding. Typical escalation triggers are listed below. ED resuscitative thoracotomy is reserved for selected traumatic arrest or profound shock under trauma protocols; drainage volume alone does not establish that indication:

1. Initial chest tube drainage $\ge 1,500$ mL of blood upon insertion.
2. Ongoing chest tube blood loss around 200 mL/hr for 3 consecutive hours is a common escalation trigger. Instability warrants earlier action.
3. Refractory shock despite balanced 1:1:1 massive transfusion (PRBCs, FFP, platelets).

Thoracentesis for Pleural Effusion

Diagnostic thoracentesis samples an unexplained effusion; therapeutic aspiration can relieve a large symptomatic effusion. Review consent, bleeding risk and imaging. For fluid aspiration, select the site with ultrasound in the procedure position, use sterile technique and local anesthesia, and enter above the rib to reduce neurovascular injury. Send fluid tests appropriate to the differential, including protein/LDH, cell count, culture or cytology. Drain therapeutic fluid slowly by manual aspiration or gravity; generally limit a single attempt to 1.5 L and stop earlier for chest pain, persistent cough or worsening breathlessness. Assess for pneumothorax, bleeding and re-expansion pulmonary edema. Postprocedure imaging is indicated for symptoms or suspected complications, rather than automatically after every uncomplicated aspiration.

Chest Tube Drainage Systems & Air Leak Troubleshooting

Differentiating Patient vs. System Air Leaks

With persistent water-seal bubbling, assess breathing and oxygenation, then inspect the insertion site, tube position, connections and collection unit. An external side hole or loose connection can mimic a patient air leak. Avoid clamping a bubbling drain because it can trap pleural air. If the source is unclear, involve the pleural or trauma team for supervised troubleshooting.

Flail Chest & Severe Pulmonary Contusion

Pathophysiology

Flail chest occurs when $\ge 3$ consecutive ribs are fractured in $\ge 2$ places, creating a free-floating chest wall segment. The segment collapses inward during inspiration and bulges outward during expiration (paradoxical respiration).

However, the primary driver of life-threatening hypoxemia is the underlying pulmonary contusion (crush injury causing alveolar hemorrhage, edema, microvascular thrombosis, and surfactant loss). Contusions evolve over 24–48 hours, causing severe V/Q mismatch and reduced lung compliance.

Multimodal Resuscitation Strategy

1. Multimodal Analgesia (First-Line): Pain causes splinting, atelectasis, secretions retention, and pneumonia. Consider thoracic epidural analgesia or a paravertebral block when appropriate to improve cough and ventilation while limiting systemic opioids. Augment with IV acetaminophen, low-dose ketamine (0.1–0.2 mg/kg/hr), and titrated opioids. Avoid acute NSAIDs in hemorrhage or renal injury.
2. Judicious Fluid Balance: Contused lung capillaries leak excessively. Overzealous crystalloid hydration precipitates alveolar flooding and ARDS. Restore perfusion when shock is present and avoid excess crystalloid once perfusion is adequate.
3. Ventilatory Support:
   • Non-Invasive Ventilation (CPAP/BiPAP): Provides internal pneumatic splinting in alert, cooperative patients without shock or severe TBI.
   • Intubation Indications: Refractory hypoxemia ($PaO_2/FiO_2 <150$), severe acidosis ($pH <7.25$, $PaCO_2 >55$ mmHg), shock, $GCS \le 8$, or multisystem trauma.
4. Surgical Rib Fixation (SSRF): Consider early surgical consultation for flail chest, ventilator weaning failure attributable to chest wall injury, or selected severely displaced fractures with persistent respiratory compromise or pain.