What is Bier's block?

What is Bier's Block?

Bier's block is an intravenous regional anesthesia technique that provides anesthesia to an entire extremity by injecting local anesthetic into a vein distal to a pneumatic tourniquet, which prevents the anesthetic from entering systemic circulation while creating a bloodless surgical field. 1, 2

Technique Overview

The procedure involves several key steps 2:

• Exsanguination: Blood is removed from the extremity by elevation and wrapping 1, 2
• Tourniquet application: A pneumatic tourniquet is inflated proximal to the surgical site 2
• Anesthetic injection: Lidocaine (typically 0.5%) is injected into a vein distal to the tourniquet 1, 3
• Anesthesia onset: The tourniquet prevents systemic circulation of the anesthetic while providing complete anesthesia distal to the tourniquet 2

Modern Variations

Traditional Upper Arm Technique

The conventional approach uses a double tourniquet on the upper arm with significant amounts of lidocaine, requiring a minimum tourniquet inflation time of 30 minutes due to concerns about cardiac and neurologic toxicity 1.

Forearm Technique (Preferred for Hand Surgery)

A forearm Bier block with tourniquet placed distal to the elbow is safer and more efficient than the traditional upper arm technique for hand procedures. 1, 3

Key advantages of the forearm approach include 1, 3:

• Reduced lidocaine dose: Only 25 mL of 0.5% lidocaine (125 mg total) is needed, compared to higher doses with upper arm technique 1, 3
• Shorter tourniquet time: Average tourniquet time of 10-16 minutes versus the standard 30-minute minimum 1, 4
• Lower complication risk: Minimal potential for cardiac or neurologic toxicity due to reduced anesthetic volume 1
• Improved efficiency: Decreased operating and recovery room times 1

Clinical Applications

Bier's block is ideally suited for 1, 3, 2:

• Carpal tunnel release (most common indication) 3
• Trigger finger release 3, 4
• Excision of hand masses 4
• Management of extremity trauma requiring surgical intervention 2
• Any hand procedure requiring anesthesia without obscuring anatomy with local infiltration 3

Safety Profile

Complication Rate

The technique demonstrates excellent safety when performed correctly 3, 4:

• Overall complication rate: 0.3-1.2% in modern series 3, 4
• Common minor complications: Transient nausea, vomiting, paresthesias, tinnitus (all self-resolving) 3, 4
• No conversions to general anesthesia required in recent large series 3

Critical Safety Considerations

The minimum tourniquet time of 30 minutes traditionally recommended for upper arm Bier blocks can be safely reduced to as little as 15-17 minutes when using the forearm technique with lower lidocaine volumes. 4

However, several variables affect safety 4:

• Proper tourniquet function: Mechanical failure can lead to premature systemic release of anesthetic 1
• Accurate dosing: Excessive lidocaine doses increase toxicity risk 1
• Correct injection site: Inadvertent arterial injection must be avoided 5

Rare Catastrophic Complications

One case report documented loss of an upper extremity following Bier block, likely due to erroneous injection of a foreign substance into the venous system, inadvertent arterial cannulation, or idiosyncratic allergic reaction 5. This underscores the importance of meticulous technique and verification of proper venous access.

Practical Implementation

For outpatient hand procedures, use a forearm tourniquet with 25 mL of 0.5% plain lidocaine (125 mg), maintaining tourniquet inflation for the duration of the procedure (typically 10-24 minutes). 1, 3

Most patients can be discharged within 49 minutes postoperatively, with only 9.1% requiring supplemental analgesics before discharge 3. Some procedures can be performed with Bier block as the sole anesthetic without additional sedation 3.