Emergency Medicine · Pulmonary Emergencies
The facts most likely to be tested
Tension pneumothorax is a clinical diagnosis characterized by hemodynamic instability and obstructive shock due to a one-way valve mechanism in the pleural space.
Physical examination reveals absent breath sounds on the affected side, hyperresonance to percussion, and tracheal deviation away from the affected side.
The immediate, life-saving intervention is urgent needle decompression performed at the fifth intercostal space in the anterior axillary line or the second intercostal space in the mid-clavicular line.
Obstructive shock occurs because the increased intrathoracic pressure decreases venous return to the heart, leading to decreased cardiac output and hypotension.
Jugular venous distension (JVD) is a classic finding resulting from the impaired venous return to the right atrium.
Definitive management following needle decompression requires the placement of a tube thoracostomy (chest tube) in the fifth intercostal space.
Imaging is contraindicated in patients with suspected tension pneumothorax because the diagnosis is made clinically and delay for a chest X-ray can be fatal.
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A 24-year-old male is brought to the emergency department after a motor vehicle collision. He is tachypneic and diaphoretic with a blood pressure of 80/50 mmHg and a heart rate of 135 bpm. Physical exam reveals absent breath sounds on the right side, hyperresonance to percussion on the right, and tracheal deviation to the left. Jugular venous distension is noted on neck inspection. The patient is becoming increasingly obtunded.
What is the most appropriate next step in management?
Immediate needle decompression
The patient presents with the classic clinical triad of tension pneumothorax (hypotension, absent breath sounds, and tracheal deviation); because this is a clinical diagnosis, immediate needle decompression is required before any imaging.
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Etiology / Epidemiology
Occurs when air enters the pleural space via a one-way valve mechanism, most commonly from penetrating trauma or mechanical ventilation.
Clinical Manifestations
Presents with hemodynamic collapse, tracheal deviation away from the affected side, and unilateral absent breath sounds.
Diagnosis
A clinical diagnosis; do not delay treatment for imaging. If stable, chest X-ray shows deep sulcus sign.
Treatment
Immediate needle decompression followed by tube thoracostomy. Never delay for imaging.
Prognosis
Rapidly fatal if untreated due to obstructive shock. Survival is excellent with immediate decompression.
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Epidemiology & Etiology
Commonly follows blunt or penetrating chest trauma, but can occur spontaneously in patients with underlying COPD or bullous emphysema. Iatrogenic causes include positive pressure ventilation or failed central line placement. It is a life-threatening emergency requiring immediate recognition.
Pertinent Anatomy
The pleural space is a potential space between the visceral and parietal pleura. In tension pneumothorax, air accumulates under pressure, causing the mediastinum to shift toward the contralateral side, compressing the superior and inferior vena cava.
Pathophysiology
A one-way valve allows air to enter the pleural space during inspiration but prevents exit during expiration. This leads to progressive intrapleural pressure elevation, causing collapse of the ipsilateral lung. The resulting mediastinal shift kinks the great vessels, drastically reducing venous return and causing obstructive shock.
Clinical Manifestations
Patients present with severe respiratory distress, tachycardia, and hypotension. Physical exam reveals unilateral absent breath sounds, hyperresonance to percussion, and tracheal deviation. Jugular venous distension is a classic sign of impaired venous return, though it may be absent in hypovolemic patients.
Diagnosis
This is a clinical diagnosis based on physical exam findings. Imaging is contraindicated in unstable patients. If the patient is stable, a chest X-ray will demonstrate a large pneumothorax with contralateral mediastinal shift and a deep sulcus sign.
Treatment
Perform immediate needle decompression using a large-bore needle in the 2nd intercostal space at the mid-clavicular line or 4th/5th intercostal space at the anterior axillary line. Follow immediately with tube thoracostomy (chest tube) connected to underwater seal drainage. Do not delay for imaging in the setting of hemodynamic instability.
Prognosis
Untreated tension pneumothorax leads to cardiac arrest within minutes. With immediate decompression, the prognosis is excellent, provided the underlying lung injury is managed. Monitor for re-expansion pulmonary edema following tube placement.
Differential Diagnosis
Cardiac Tamponade: Beck's triad present without absent breath sounds
Massive Hemothorax: Dullness to percussion instead of hyperresonance
Myocardial Infarction: No respiratory distress or unilateral breath sound changes
Pulmonary Embolism: Clear breath sounds and no tracheal deviation
Simple Pneumothorax: Stable vitals and no mediastinal shift