Overview
- 1.
Two techniques can be used to perform a digital block:
- a.
Tendon sheath injection
- b.
Web space injection
- a.
- 2.
The web space injection technique is more painful but provides a complete digital block more reliably.
Indications for Use
A digital block is used for soft tissue injuries about the finger distal to the proximal interphalangeal joint.
Precautions
- 1.
Warnings not to use epinephrine in a digit are based on misinterpretations of invalidated data.
- 2.
Do not use a digital block if the metacarpophalangeal (MP) joint is surrounded by infection.
Pearls
When administering a tendon sheath injection, the dorsal block can be enhanced by skirting the tendon sheath on either side and injecting on the dorsum of the hand.
Equipment
- 1.
Antiseptic: A chlorhexidine prep stick or alcohol-soaked gauze
- 2.
Syringe: A 10-mL syringe
- 3.
Needles:
- a.
A large-bore, blunt-tipped drawing-up needle
- b.
A 1½-in., 25-gauge needle
- a.
- 4.
Anesthetics (for a typical adult):
- a.
Lidocaine: 5 mL of 2%
- b.
Bupivacaine: 5 mL of 0.5%
- a.
- 5.
Sterile gloves
- 6.
4 × 4 in. gauze
Basic Technique
- 1.
Patient positioning: Place the hand on a bedside table with the arm in pronation.
- 2.
Landmarks:
- a.
The web space on either side of the affected digit or tendon sheath.
- b.
The digital nerves are injected on either side of the affected digit.
- a.
- 3.
Steps:
- a.
Position the patient.
- b.
Prepare the anesthetic.
- c.
Palpate the landmarks.
- d.
Prepare the skin with an antiseptic solution.
- e.
Numb the skin with ethyl chloride (if desired).
- f.
Inject the anesthetic:
- (1)
Inject the anesthetic on both sides for a web space block.
- (2)
Inject the anesthetic on the volar tendon sheath and incorporate the dorsal skin.
- (1)
- g.
Place a sterile bandage over the injection site.
- a.
Detailed Technique
- 1.
Position the patient.
- 2.
Prepare the anesthetic. A single 10-mL syringe is required.
- 3.
Palpate the landmarks.
- 4.
Prepare the skin with an antiseptic solution.
- 5.
Numb the skin with ethyl chloride (if desired).
- 6.
Inject the anesthetic (web space injection):
- a.
Enter from the dorsal aspect at a 90-degree angle to the skin.
- b.
Insert the needle, aiming in the volar direction.
- c.
Maintain patient contact to note any paresthesias.
- d.
Aspirate the needle before injection to ensure that intravascular placement has been avoided.
- e.
Advance the needle volarly until it is almost subcutaneous.
- f.
Inject 2 mL of the anesthetic. Be vigilant for any warning signs of intravascular injection.
- g.
Slowly withdraw the needle. Repeatedly aspirate and then inject another 1 mL as the needle is withdrawn.
- h.
Repeat the injection on the other side of the digit.
- a.
- 7.
Inject the anesthetic (tendon sheath injection):
