Identify the type of nerve block shown in the image.
A. Digital Block.
B. Axillary Block.
C. Brachial Plexus Block.
D. Bier’s Block.
Ans:D. Bier’s Block.
Also referred as “INTRAVENOUS REGIONAL ANAESTHESIA”
- Provides intense anesthesia for short cases (45-60 minutes) on the forearm or hand.
- A double pneumatic tourniquet is placed on the arm after an IV is started in the hand.
- The arm is elevated and exsanguinated, the proximal tourniquet is inflated above systolic pressure
- So that no blood can enter in that limb and it remains exsanguinated.
- Lidocaine without adrenaline is the DOC for the technique.
- A few clinician prefers prilocaine over lidocaine because of its higher therapeutic index – least toxic LA
- Tornique cuff deflation, premature release or failure of tourniquet can cause release of LA into circulation and toxicity may occur
- So, cardiotoxic LAs like bupivacaine and etidocaine are contraindicated for Bier’s block
- Anesthesia is achieved after 5-10 minutes. After 20-30 minutes tourniquet pain develops, at which point the distal tourniquet (which is over anesthetized skin) is inflated and the proximal cuff is deflated.
Important to note in Bier’s block:
1. Application of IVRA and sickle cell anemia:
- The basic idea in intravenous regional anesthesia is to exsanguinate the extremity by applying an arterial tourniquet to isolate it from circulation and inject the local anesthetic into the extremities in the venous system.
- This technique of intravenous regional anesthesia makes it dangerous for application in sickle cell anemia because,
- Children with sickle cell anemia are prone to develop massive hemolysis in case of low oxygen tension, or in cases where blood flow slow’s down.
- During tourniquet application in intravenous regional anesthesia, blood flow slows down and can precipitate the acute hemolytic crisis in the patient with sickle cell anemia.
- Therefore, IVRA is contraindicated in sickle cell anemia.
Other Upper Extremities Nerve Blocks:
- Generally performed at the level of the cricoid cartilage in the interscalene groove.
- Best for shoulder and upper arm surgery.
- Performed at the level of the trunks, which are tightly bundled vertically on top of the first rib and just posterior to the subclavian artery as it prepares to dive under the clavicle. Provides excellent anesthesia for the entire arm and hand.
- Performed at the level of the cords as the plexus emerges from beneath the clavicle and enters the axilla. Like the supraclavicular, this block provides good homogeneous anesthesia to the hand, forearm elbow and upper arm.
- Performed at the level of the branches. Best used for procedures distal to the elbow. The axillary pulse is the key landmark, and the block should be performed at the highest level that the pulse is palpable.
Digital block :
- Isolated finger surgery can be performed with a digital block. Each digit is supplied by 4 small digital nerves that enter the digit at its base in each of the four corners.