8.10:
Local Anesthetics: Clinical Application as Intravenous Regional Anesthesia
Intravenous regional anesthesia or the Bier block technique uses exsanguinated or blood-drained vessels to transport local anesthetics or LAs to the peripheral nerve trunks. This technique is mainly used for surgeries on the upper extremity.
In this technique, an IV cannula is placed close to the surgery site. Then the arm is raised to drain the blood passively. Starting from the cannula insertion site, the arm is tightly bandaged to obstruct blood flow.
Next, a tourniquet is placed around the proximal arm and inflated to 100 mm HG above the patient's systolic blood pressure to isolate the veins from the systemic circulation. After removing the bandage, the LA is injected into the cannula to pass through the exsanguinated veins.
The injected LA causes complete anesthesia of the extremity within 10 minutes. However, the tourniquet should remain inflated for 30 minutes to prevent the LAs from entering the systemic circulation.
Premature deflation of the tourniquet causes the pain to return quickly and releases toxic levels of LA into circulation.
8.10:
Local Anesthetics: Clinical Application as Intravenous Regional Anesthesia
Intravenous regional anesthesia or the Bier block technique is used to anesthetize a specific limb or extremity. It uses exsanguinated or blood-drained vessels to transport local anesthetics or LAs to the peripheral nerve trunks. Lidocaine without vasoconstrictors like epinephrine is most commonly used for this technique. Other drugs used are prilocaine, ropivacaine, and chloroprocaine. Bupivacaine is not recommended for this technique due to its high cardiac toxicity.
One of the advantages of the Bier block technique is its rapid onset of action. Anesthesia is achieved within five minutes after the injection, allowing for efficient pain control during procedures. Additionally, the procedure can be performed on an outpatient basis, avoiding the need for general anesthesia and its associated risks. The technique requires minimum additional equipment and can be done in a simple clinical environment.
However, its use is limited to certain areas, like the arm. Other disadvantages include the quick return of pain after tourniquet deflation and high systemic toxicity on premature tourniquet release. Contraindications of this technique include hypersensitivity to local anesthetics, deep vein thrombosis or impaired limb perfusion, hypertension, open wounds, and significant limb injuries.