What is the most appropriate regional nerve block for an upper lip laceration?

Infraorbital Nerve Block for Upper Lip Laceration

The infraorbital nerve block is the definitive choice for anesthetizing upper lip lacerations, with the intraoral approach being superior to the percutaneous technique. 1

Anatomic Rationale

The superior lateral lip receives its sensory innervation from the infraorbital nerve, a terminal branch of the maxillary division of the trigeminal nerve, making this the anatomically correct block for upper lip anesthesia. 1

Preferred Technique: Intraoral Approach

Use the intraoral approach rather than the percutaneous approach for superior outcomes. 2 The evidence demonstrates:

• Longer duration of anesthesia (1.6 hours vs 0.9 hours with percutaneous approach) 2
• Higher success rate (100% vs 75% for percutaneous technique) 2
• Less painful administration when topical anesthetic is applied first 2
• Better postoperative analgesia in clinical practice 3

Step-by-Step Procedural Technique

Preparation

• Apply topical anesthetic (viscous lidocaine for 1 minute) to the oral mucosa before injection 1, 2
• Prepare the injection site with antiseptic solution 1
• Use a 27-gauge needle 2

Injection Protocol

• Aspirate before injection to ensure the needle is not intravascular—this is mandatory to prevent systemic toxicity including seizures, cardiovascular collapse, and respiratory arrest 1
• Inject slowly over 20 seconds to minimize discomfort and tissue trauma 1, 2
• Use 2.5 mL of 2% buffered lidocaine (or use amide-type local anesthetics such as lidocaine or bupivacaine as preferred agents) 1, 2

Needle Direction

• Direct the needle medially and cephalad until the infraorbital foramen is reached 4
• The infraorbital canal angles approximately 44 degrees relative to the Frankfurt plane 5
• Males may require slightly steeper angulation (4 degrees more) than females 5

Critical Safety Considerations

• Always aspirate before every injection to prevent intravascular administration 1
• Use ultrasound guidance when available to reduce the risk of local anesthetic systemic toxicity 1
• Warm the anesthetic solution rather than using room temperature solution to reduce discomfort 1
• Allow sufficient onset time (typically several minutes) before proceeding with laceration repair to avoid perceived block failure 1
• Have resuscitation equipment immediately available 6

Common Pitfalls to Avoid

• Do not skip the aspiration step—this is the most critical safety measure 1
• Do not inject too rapidly, as this increases pain and tissue trauma 1
• Do not proceed with the procedure before adequate onset time has elapsed 1
• Avoid using cold anesthetic solution, which increases patient discomfort 1