Bier block is intravenous regional anesthesia which was originally introduced by August K. G. Bier in 1908 and thus the name.
The main advantages of this technique are its simplicity and reliability.
With tourniquet tied intravenous anaesthetic agent like lignocaine is injected in previously exsanguinated limb. There is a direct diffusion of the local anesthetic from the vessels into the nearby nerves as the drug is not distributed due to circulation blockage by tourniquet.
Peripheral nerve endings of the extremities are nourished by small blood vessels. Injection of a local anesthetic solution into a venous system results in diffusion of the local anesthetic into the nerve endings with the consequent development of anesthesia. The duration of the anesthesia and analgesia are limited by the duration tourniquet.
A small IV intravenous catheter (e.g, 22-gauge) is introduced and secured in the dorsum of the patient’s hand on the affected limb. After exsanguination of the limb, the cuffs are inflated.
When double cuffs are used following sequence of events carry better exsanguination and bring distal cuff in zone of anesthesia.
The usual recommended pressure is systolic blood pressure+100 mm Hg
The anaesthetic agent is pushed through the cannula. Within 5 minute, the effect of anesthesia can be noticed.
Note: After about 30-45 minutes the patients report discomfort due to tourniquet pressure. When this happens, the distal cuff is inflated and proximal cuff is deflated. This provides another 15-20 minutes of relief from discomfort. The sequence is
When the surgery is done, a gradual deflation of the tourniquet is done to avoid toxicity of the drug in the body. Some anesthetists recommend deflation for 10 seconds and reinflation for one minute and then gradual deflation.
The release of the tourniquet will result in a rapid resolution of anesthesia and analgesia.
Complications are mostly limited to systemic toxicity from the local anesthetic or problems with the tourniquet.
- Systemic toxicity of local anesthetic
- Hematoma formation at iv catheter site
- Engorgement of the extremity – Avoidable with proper tourniquet application
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