What are the key points to know about tension pneumothorax?

Tension Pneumothorax: Non-Negotiable Essentials

Definition & Pathophysiology

Tension pneumothorax is a life-threatening emergency where intrapleural pressure exceeds atmospheric pressure throughout the entire respiratory cycle due to a one-way valve mechanism, causing progressive air accumulation that impairs venous return, reduces cardiac output, and leads to cardiovascular collapse. 1

• Air enters the pleural space during inspiration but cannot escape during expiration, creating progressive pressure buildup 1
• The mechanism causes mediastinal shift, reduced venous return, and kinking of great vessels leading to hemodynamic instability 1, 2
• Critical point: Tension development is NOT dependent on pneumothorax size—small pneumothoraces can become life-threatening 1

Clinical Recognition (DO NOT WAIT FOR IMAGING)

The diagnosis is purely clinical—never delay treatment for radiographic confirmation as this is immediately life-threatening. 3

Cardinal Signs (Recognize These Immediately):

• Rapid labored respiration with progressive respiratory distress 1, 3
• Cyanosis, profuse sweating, and tachycardia 1
• Hypoxemia and hypotension (hypotension is a LATE finding that immediately precedes cardiorespiratory collapse) 2
• Decreased or absent breath sounds on affected side 4
• Progressive increase in airway pressure on mechanical ventilation 4

High-Risk Scenarios (Maintain High Suspicion):

• Patients on mechanical ventilation or non-invasive ventilation who suddenly deteriorate or develop pulseless electrical activity (PEA) arrest 1, 3
• Frequently missed in ICU settings 1
• Recent central line attempts (especially subclavian) 4
• Positive pressure ventilation can convert undetected small pneumothorax into tension pneumothorax 4

Immediate Management (Time-Critical)

Step 1: Needle Decompression (FIRST-LINE EMERGENCY TREATMENT)

Use a 7 cm needle (minimum 4.5 cm) for initial decompression—shorter needles fail in 32.84% of cases because chest wall thickness exceeds 3 cm in 57% of patients. 1, 3

Needle Specifications:

• Length: 7 cm preferred (minimum 4.5 cm, 14-gauge or larger) 1, 3
• Each additional cm of needle length reduces failure rate by 7.76% 1
• Standard 3-6 cm needles are inadequate in most patients 1

Site Selection (CRITICAL—Location Matters):

For RIGHT-sided tension pneumothorax:

• 2nd intercostal space, midclavicular line (2MCL) OR 5th intercostal space, midaxillary line (5MAL) 1, 3

For LEFT-sided tension pneumothorax:

• ONLY 2nd intercostal space, midclavicular line (2MCL) to avoid cardiac injury 1, 3
• Do NOT use lateral approaches on the left side due to cardiac injury risk 1

Technique:

• Insert cannula perpendicular to chest wall 3
• Advance fully to the hub 3
• Hold needle/catheter unit in place for 5-10 seconds before removing needle 3
• Leave the cannula in place until chest tube is functioning 1, 3

Step 2: Definitive Management

Insert chest tube immediately after needle decompression—the cannula is only a temporizing measure. 1, 3

• Connect to underwater seal drainage system 3
• Confirm proper function by observing bubbling in underwater seal before removing decompression cannula 1, 3
• Obtain chest radiograph to confirm tube position and lung re-expansion 3

Step 3: Supportive Care

• Administer high-concentration oxygen immediately 1
• Provide adequate analgesia 3
• Monitor vital signs and respiratory status continuously 3

Critical Pitfalls to Avoid

Common Error #1: Using needles that are too short

• 57% of patients have chest wall thickness >3 cm, making standard needles ineffective 1
• Use minimum 4.5 cm, preferably 7 cm needles 1, 3

Common Error #2: Delaying treatment for imaging

• This is a clinical diagnosis requiring immediate intervention 3
• Chest X-ray findings correlate poorly with clinical severity 1

Common Error #3: Removing decompression cannula before chest tube is functional

• Keep cannula in place until bubbling confirms chest tube function 1, 3

Common Error #4: Incorrect anatomic site identification

• Paramedics and physicians frequently misidentify the correct location 5
• Practice landmark identification: 2nd ICS is below the 2nd rib, MCL is midpoint of clavicle

Common Error #5: Missing diagnosis in ventilated patients

• Any sudden deterioration or PEA arrest in ventilated patients = tension pneumothorax until proven otherwise 1, 3
• Progressive hypoxemia and tachycardia are EARLY signs—do not wait for hypotension 2

Special Populations

Patients on positive pressure ventilation:

• Always require tube thoracostomy as positive pressure maintains air leak 3
• Small undetected pneumothorax can rapidly progress to tension with positive pressure 4

Cystic fibrosis patients:

• Higher mortality risk (median survival 30 months after pneumothorax) 1
• 40% develop contralateral pneumothoraces 1