What are the recommended landmarks for chest drain insertion?

Recommended Landmarks for Chest Drain Insertion

Chest drains should be inserted in the 'safe triangle' in the mid-axillary line between the 4th and 5th intercostal space to minimize risk to vital structures. 1

The 'Safe Triangle' Anatomical Definition

The 'safe triangle' is precisely defined as:

• Bordered anteriorly by the lateral edge of pectoralis major muscle
• Bordered posteriorly by the anterior border of latissimus dorsi
• Bordered inferiorly by a line superior to the horizontal level of the nipple
• With an apex below the axilla 2, 1

This anatomical location is optimal because it:

• Minimizes risk to vital structures including intercostal vessels
• Avoids damage to underlying organs
• Prevents injury to breast tissue that could result in unsightly scarring
• Reduces risk of traumatic insertion 2

Ultrasound-Guided Placement

• Ultrasound guidance is strongly recommended to:

  • Confirm effusion/pneumothorax location
  • Identify the optimal insertion site
  • Avoid vital structures
  • Reduce complications 1

• Small bore percutaneous drains should be inserted at the site suggested by ultrasound 2

• Large bore surgical drains should also be placed at the site suggested by ultrasound, but preferentially within the 'safe triangle' 2

Anatomical Considerations

Nipple Position as a Landmark

• The nipple generally corresponds to the 5th intercostal space in both male and female patients when in supine position 3
• Even in female patients with larger breasts, when lying supine, the nipple remains a reliable landmark as gravity pulls breast tissue laterally rather than inferiorly 3

Intercostal Vessel Considerations

• The intercostal arteries run in the middle of the intercostal spaces posteriorly
• Laterally (in the mid-axillary line), they run under the ribs, making this position safer 2
• This is why posterior drain placement carries a higher risk of vascular injury

Patient Positioning

For patients under local anesthesia:

• Position slightly rotated with the arm on the affected side behind the head to expose the axillary area
• Alternative positions include upright leaning over a table with a pillow or lateral decubitus position 1

For patients under general anesthesia:

• Position flat on the back
• If the marked site is posterior, roll the patient to facilitate access 2

Common Pitfalls and Safety Considerations

1. Never use substantial force or a trocar to insert a drain 2
2. Never insert too posteriorly due to risk of intercostal artery injury
3. Never insert too low (below the safe triangle) due to risk of diaphragm/abdominal organ injury
4. Never insert without ultrasound guidance when available
5. Always confirm proper placement with a post-procedure chest radiograph 2, 1

In neonates, special consideration must be given to the narrow safety corridor between the chest wall and heart, particularly for left-sided pneumothoraces, where the distance can be as small as 2.8-5.2 mm depending on the intercostal space 4

By following these landmark guidelines and using appropriate imaging guidance, the risk of complications from chest drain insertion can be significantly minimized while ensuring effective treatment.