Tension Pneumothorax: Recognition & Needle Decompression

By Chester "Chet" Shermer, MD, FACEP · 2026-05-04

About the author: Dr. Chester Shermer, MD, FACEP

Why Tension Pneumothorax Is a Leading Cause of Preventable Battlefield Death

Tension pneumothorax is the second leading cause of preventable death on the battlefield, behind only uncontrolled hemorrhage. It is also one of the most treatable — if recognized and treated in time.

The challenge is that in a tactical environment, the classic textbook signs are often absent, unreliable, or obscured by noise, body armor, and the chaos of combat. This guide will walk you through a practical, TCCC-aligned approach to recognition and needle decompression.

Understanding the Pathophysiology

When air enters the pleural space and cannot escape — due to a one-way valve effect from a penetrating wound or ruptured alveolus — pressure builds progressively with each breath. This causes:

1. Ipsilateral lung collapse — the affected lung cannot expand
2. Mediastinal shift — the heart and great vessels are pushed toward the unaffected side
3. Vena cava kinking — venous return to the heart is impaired
4. Obstructive shock — cardiac output falls, leading to cardiovascular collapse

Without intervention, tension pneumothorax is rapidly fatal.

Recognition in Tactical Environments

Classic Signs (Often Unreliable in the Field)

The signs taught in the classroom — tracheal deviation, jugular venous distension (JVD), absent breath sounds — are late findings that are difficult to assess in a noisy, low-light tactical environment with a casualty in body armor.

Do not wait for tracheal deviation or JVD to treat a suspected tension pneumothorax. These are late, pre-terminal findings.

Practical Recognition: Focus on These

In the field, base your clinical suspicion on:

• Mechanism of injury: penetrating chest trauma, blast injury, rib fractures from blunt trauma
• Respiratory distress: increasing difficulty breathing, tachypnea, accessory muscle use
• Unilateral decreased breath sounds: the most reliable bedside finding — assess with your ear against the chest wall
• Tachycardia: early compensatory response
• Hypotension: indicates obstructive shock — this is a late and urgent finding
• Deteriorating mental status: hypoxia and decreased cerebral perfusion

The MARCH Algorithm Context

Tension pneumothorax falls under R for Respiration in the MARCH algorithm. After controlling massive hemorrhage and securing the airway, a systematic respiratory assessment is mandatory for all penetrating chest trauma casualties.

Needle Decompression: Step-by-Step

Indications

Perform needle decompression when you have:

• Penetrating chest trauma AND respiratory distress or hemodynamic instability
• Blunt chest trauma with suspected tension pneumothorax
• Any casualty with a chest seal who is deteriorating (consider occluded or malfunctioning seal)

Equipment

• 14-gauge or 10-gauge, 3.25-inch (8 cm) needle-catheter — standard military issue; longer needles are required due to body armor and chest wall thickness in military-age males
• Alternatively: a commercial 14-gauge × 3.25-inch needle decompression device (e.g., the ARS)

Procedure: 2nd Intercostal Space, Midclavicular Line (2ICS-MCL)

1. Identify the 2nd intercostal space by palpating the sternal angle (angle of Louis) and moving laterally to the 2nd rib; the space below is the 2nd ICS
2. Move to the midclavicular line — directly below the midpoint of the clavicle
3. Insert the needle perpendicular to the chest wall, just above the 3rd rib (to avoid the neurovascular bundle on the inferior margin of the 2nd rib)
4. Advance until you feel a loss of resistance and hear a rush of air
5. Remove the needle, leaving the catheter in place
6. Secure the catheter and monitor for clinical improvement

Procedure: 4th/5th Intercostal Space, Anterior Axillary Line (4/5 ICS-AAL)

The anterior axillary line approach is one of two CoTCCC-recommended sites — current TCCC guidance allows either site. Many providers favor the AAL in tactical settings because it avoids the internal mammary artery and is more reliable in patients with thick chest walls:

1. Identify the 4th or 5th intercostal space at the anterior axillary line (the line extending from the anterior axillary fold)
2. Insert the needle perpendicular to the chest wall, just above the rib
3. Advance until loss of resistance; remove needle, secure catheter

Signs of Successful Decompression

• Rush of air from the needle
• Improvement in respiratory distress
• Improvement in hemodynamic status (rising BP, slowing HR)
• Improved mental status

Chest Seals and Tension Pneumothorax

Vented vs. Non-Vented Seals

• Vented chest seals (e.g., Hyfin Vent, HALO Vent) are preferred for penetrating chest wounds — the flutter valve allows air to escape while preventing air entry
• Non-vented seals can convert an open pneumothorax to a tension pneumothorax if the wound is not completely sealed or if air continues to accumulate

Managing a Deteriorating Casualty with a Chest Seal

If a casualty with a chest seal deteriorates:

1. Burp the seal — lift one edge to allow trapped air to escape
2. If no improvement, perform needle decompression on the affected side
3. Replace the chest seal after decompression

Common Mistakes

Key Takeaways

• Tension pneumothorax is the second leading cause of preventable battlefield death — treat it aggressively
• Classic signs (tracheal deviation, JVD) are late findings — do not wait for them
• Either CoTCCC-recommended site may be used — the 4th/5th ICS at the anterior axillary line or the 2nd ICS at the midclavicular line — with a 14g (or 10g) × 3.25-inch needle
• Always reassess after decompression and consider bilateral treatment if the casualty does not improve

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