What is the optimal location for a chest drain insertion?

Optimal Location for Chest Drain Insertion

The optimal location for chest drain insertion is the 'safe triangle' in the mid-axillary line, specifically between the 4th and 5th intercostal space. 1, 2

The 'Safe Triangle' Defined

The 'safe triangle' is anatomically defined as:

• Bordered by the anterior border of latissimus dorsi
• Bordered by the lateral border of pectoralis major muscle
• A line superior to the horizontal level of the nipple
• An apex below the axilla 1

This location minimizes risk to underlying structures and avoids damage to muscle and breast tissue that could result in unsightly scarring.

Specific Recommendations Based on Drain Type

Small Bore Percutaneous Drains

• Should be inserted at the optimum site suggested by chest ultrasound 1
• Typically placed in the 4th or 5th intercostal space in the mid-axillary line 2, 3
• Ultrasound guidance is strongly recommended to identify the exact location

Large Bore Surgical Drains

• Should be inserted at the optimum site suggested by ultrasound
• Preferentially placed in the mid-axillary line through the 'safe triangle' 1
• Size 8-12 FG catheters are recommended as they are as effective as larger tubes while causing less discomfort 1

Important Anatomical Considerations

• Intercostal arteries run in the middle of the intercostal spaces posteriorly, whereas laterally they run under the ribs 1
• This creates a higher risk of traumatic insertion if drains are placed posteriorly
• The neurovascular bundle is not always safely protected in the subcostal groove as traditionally taught 4
• The "Safe Zone" for insertion is between 50-70% of the way down an interspace to avoid the variably positioned superior intercostal neurovascular bundle 4

Positioning Considerations

• For cooperative patients under local anesthesia: position slightly rotated, with the arm on the affected side behind the patient's head to expose the axillary area 1
• Alternative positions include upright leaning over a table with a pillow or in the lateral decubitus position 1
• For patients under general anesthesia: position flat on their back, with adjustment if the marked site is posterior 1

Common Pitfalls and How to Avoid Them

1. Incorrect space identification: Studies show that traditional methods of identifying the fifth intercostal space can be unreliable, with potential for insertion in the 6th intercostal space or below in up to 80% of cases 5

   • Solution: Use real-time ultrasonography to confirm the intercostal space during the procedure

2. Gender-specific risks: In 44% of women, using the nipple to identify the fifth intercostal space may result in locating the sixth intercostal space or below, risking subdiaphragmatic insertion 5

   • Solution: Rely on ultrasound guidance rather than external landmarks in women

3. Traumatic insertion: Using trocars or excessive force can cause damage to intrathoracic structures 1

   • Solution: Never use substantial force or trocars for insertion

4. Complications: Potential complications include hemothorax, dislocation, lung lacerations, and injury to organs in the thoracic or abdominal cavity 2, 3

   • Solution: Follow proper technique and use ultrasound guidance when available

Remember that a chest radiograph should always be performed after insertion of a chest drain to check the drain position and ensure a pneumothorax has not developed 1.