What are the safest injection techniques to avoid vascular complications when using hyaluronic acid (HA) fillers for nasolabial fold treatment?

Safe Injection Techniques for Nasolabial Fold Treatment to Avoid Vascular Complications

The safest injection technique for nasolabial fold treatment is using a cannula rather than a needle, combined with pre-procedural Doppler ultrasound mapping of facial vasculature to avoid arterial injury. 1, 2

Anatomical Considerations and Pre-Procedure Assessment

• Vascular mapping is essential: Use Doppler ultrasound before injection to identify the facial artery location, which varies significantly between patients 1

  • 31% of patients have facial artery lateral to the nasolabial fold
  • 13% have it in the subdermal layer
  • 29% have it in the subcutaneous layer
  • 24% have it in the muscular layer
  • 4% have it in the submuscular layer

• Patient preparation:

  • Apply topical anesthesia (compounded pharmacy-based, not over-the-counter) for at least 30 minutes prior to procedure 3
  • Ensure proper skin cleansing with antibacterial soap or scrub followed by 70% alcohol in a circular rubbing motion 3

Injection Techniques by Device Type

Cannula Technique (Preferred)

• Use a 25G cannula with only two entry points for the nasolabial fold 3
• Benefits: Significantly reduces pain, edema, hematoma, and redness compared to needles 2
• Injection depth: Based on pre-procedure ultrasound, inject in layers that bypass the facial artery 1
• Direction: Use retrograde injection technique (withdrawing while injecting) 3

Needle Technique (When necessary)

• Use small gauge needles (27-30G) 3
• Injection depth: Above the orbicularis oris muscle for vessel safety 3
• Angle: Approximately 45-degree angle of insertion 3
• Technique: Inject in a retrograde fashion into each quadrant 3
• Volume: 0.2 to 0.5 mL per quadrant 3

Layer-Specific Approach Based on Ultrasound Findings

1. When facial artery is lateral to nasolabial fold:

   • Safe to inject in subdermal, subcutaneous, and deep layers along the fold

2. When facial artery is beneath the nasolabial fold:

   • Target layers above or below the identified artery location
   • Avoid the specific layer containing the artery

3. For deep nasolabial folds:

   • Consider intraoral approach to access Ristow's space, which may reduce risk of vascular complications 4

Safety Measures to Prevent Vascular Complications

1. Pre-injection:

   • Map facial vasculature with Doppler ultrasound 1
   • Ensure proper skin preparation with antiseptic 3
   • Have patient wear surgical mask during procedure 3

2. During injection:

   • Inject slowly with minimal pressure
   • Aspirate before injection when using needles
   • Limit volume to 0.2-0.5 mL per quadrant 3
   • Maintain sterile technique throughout procedure 3

3. Post-injection:

   • Monitor for immediate signs of vascular compromise (blanching, pain)
   • Advise patient to avoid sunlight and heavily scented facial products for 24 hours 3

Treatment Schedule

• Optimal results require a minimum of three treatments with 21-day intervals 5
• Maintenance treatments recommended every 6 months 5
• For long-term correction, repeat treatments show effectiveness for at least 48 weeks in approximately 80% of patients 6

Potential Complications and Management

• Bruising: Most common side effect, typically resolves within 2 weeks without treatment 1
• Vascular occlusion: Immediate recognition and management is critical
• Infection: Rare with proper antiseptic technique

The evidence clearly demonstrates that using a cannula with pre-procedural Doppler ultrasound mapping provides the safest approach for nasolabial fold injections, significantly reducing the risk of vascular complications while maintaining effective aesthetic outcomes.