Anatomical Considerations for Mediastinal and Pleural Chest Tube Insertion
For safe and effective chest tube insertion, the 'safe triangle' in the mid-axillary line between the 4th and 5th intercostal space is the optimal anatomical location for both mediastinal and pleural chest tubes. 1
Anatomical Landmarks and Safe Zones
The 'Safe Triangle'
- Definition: Bordered by the anterior border of latissimus dorsi, lateral border of pectoralis major muscle, and a line superior to the horizontal level of the nipple, with an apex below the axilla 1
- Optimal intercostal space: 4th-5th intercostal space in the mid-axillary line 1
- Rationale: This location minimizes risk to vital structures including:
- Intercostal vessels (which run under the ribs laterally but in the middle of intercostal spaces posteriorly) 2
- Abdominal organs (particularly with lower insertions)
- Major neurovascular bundles
Patient Positioning
- For conscious patients under local anesthesia: Position slightly rotated with arm on affected side behind head to expose axillary area 2
- Alternative positions:
- Upright leaning over a table with a pillow
- Lateral decubitus position 2
- For general anesthesia: Position flat on back, with adjustments if the marked site is posterior 2
Imaging Guidance
- Ultrasound guidance is strongly recommended to:
- Confirm effusion/pneumothorax location
- Identify optimal insertion site
- Avoid vital structures
- Reduce complications 2
- CT guidance may be necessary for complex loculated effusions or difficult anatomy 2
Drain Selection and Insertion Technique
Drain Size
- Small-bore drains (8-12 FG) are preferred for most situations as they:
- Large-bore drains may be considered for:
- Hemothorax
- Very thick purulent effusions
- Large air leaks 2
Insertion Technique
- Never use substantial force or trocars during insertion to avoid traumatic complications 2, 1
- Seldinger technique is recommended for small-bore catheter insertion 2
- Blunt dissection is recommended for larger tubes (>24F) 3
- Sterile technique is essential:
- Sterile gloves, gown, equipment
- Sterile towels after effective skin cleansing with betadine or chlorhexidine
- Large area of skin preparation 2
Common Complications and Anatomical Pitfalls
Potential Complications
- Vascular injury: Particularly to intercostal vessels
- Organ injury: Lung, liver, spleen, heart
- Nerve damage: To intercostal nerves or lateral thoracic wall nerves
- Misplacement: Into fissures or subcutaneous tissues
- Infection: At insertion site or empyema
Anatomical Pitfalls to Avoid
- Posterior insertion: Higher risk of intercostal artery injury as they run in the middle of intercostal spaces posteriorly 1
- Too low insertion: Risk of subdiaphragmatic placement and abdominal organ injury
- Too anterior insertion: Risk of internal mammary artery injury
- Too superior insertion: Risk of neurovascular bundle injury (which runs along the inferior border of ribs)
Post-Insertion Management
- Chest radiograph must be performed after insertion to:
- Connect to unidirectional flow drainage system (underwater seal bottle) kept below patient's chest level 2
- Secure drain properly to prevent dislodgment:
- Non-absorbable suture to narrow incision around drain
- Stay suture through skin and criss-crossed up drain
- Special dressings/fixation devices for small catheters 2
Special Considerations for COVID-19
During the COVID-19 pandemic:
- Consider chest tube insertion as an aerosol-generating procedure
- Use appropriate PPE (Level 2)
- Take extra precautions to avoid open communication with pleural space
- Consider clamping ventilator circuit before accessing pleural cavity in ventilated patients 2
By understanding and respecting these anatomical considerations, clinicians can minimize complications and optimize outcomes for patients requiring chest tube insertion.