Digital Block

Published on 16/03/2015 by admin

Filed under Orthopaedics

Last modified 22/04/2025

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Chapter 5 Digital Block

Overview

1. Two techniques can be used to perform a digital block:

a. Tendon sheath injection
b. Web space injection

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 performing 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: Chlorhexidine prep stick or alcohol-soaked gauze
2. Syringe: 10-mL syringe
3. Needle:

a. Large-bore, blunt-tipped, drawing-up needle
b. 1½-inch, 25-gauge needle

4. Anesthetic (for a typical adult):

a. Lidocaine: 5 mL of 2%
b. Bupivacaine: 5 mL of 0.5%

5. Sterile gloves
6. 4 × 4 inch gauze

Basic technique

1. Patient positioning: Place the hand on a bedside table with the arm in pronation.
2. Landmarks:

a. 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.

3. Steps:

a. Position the patient.
b. Prepare the anesthetic.
c. Palpate landmarks.
d. Prepare the skin with an antiseptic solution.
e. Numb the skin with ethyl chloride (if desired).
f. Inject anesthetic:

(1) Inject anesthetic on both sides for a web space block.
(2) Inject anesthetic on the volar tendon sheath and incorporate dorsal skin.

g. Place a sterile bandage over the injection site.

Detailed technique

1. Position the patient.
2. Prepare the anesthetic. A single 10-mL syringe is required.
3. Palpate landmarks.
4. Prepare the skin with an antiseptic solution.
5. Numb the skin with ethyl chloride (if desired).
6. Inject anesthetic (web space injection):

a. Enter from the dorsal aspect at a 90-degree angle to the skin.
b. Insert the needle, aiming in a 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 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.

7. Inject anesthetic (tendon sheath injection):

a. Enter from the volar aspect just proximal to the MP joint at a 90-degree angle to the skin for the thumb (Figure 5-1) and fingers (Figure 5-2).
b. Insert the needle, aiming at the flexor sheath in a dorsal 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 until it contacts the tendon sheath.
f. Inject 5 mL of anesthetic. Be vigilant for any warning signs of intravascular injection.
g. Slowly withdraw the needle to the level of the subcutaneous tissue.
h. Redirect the needle to skirt the flexor sheath on either side and advance into the dorsum of the hand (Figure 5-3). Repeatedly aspirate the needle and then inject another 2.5 mL.
i. Repeat the injection on other side of the flexor sheath.

8. Place a sterile bandage over the injection site.
image

Figure 5-1

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Figure 5-2

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Figure 5-3

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