ANESTHESIA FOR HAND SURGERY
For procedures lasting more than 45 minutes and/or bony procedures with significant pain expected, surgeons often prefer to use regional anesthesia. This allows for longer tourniquet times without discomfort and continuous pain relief for 12 to 24 hours postoperatively. The choice of supraclavicular versus axillary block and the mixture of short-versus long-acting anesthetic is chosen by the anesthesiologist in consultation with the surgeon, directing the anesthesia to the nerves affecting the region of the hand being operated upon.
Bier Block Anesthesia
The usual risks of general anesthesia can also be avoided with the use of Bier block regional anesthesia. Axillary and supraclavicular blocks are often time consuming, especially in patients who are in significant pain and unable to fully cooperate with the examiner. Intravenous regional, or Bier block, anesthesia is a good choice for reductions of the forearm fractures and for elective procedures in the hand. The method is safe and reliable, producing adequate muscle relaxation and pain relief for up to 45 minutes without tourniquet discomfort.
First, an intravenous line is established in the normal, uninjured forearm to provide immediate access for the administration of sedative medications. In the injured limb, a butterfly needle is placed in a dorsal vein in the hand, distal to the fracture site. A 0.33% lidocaine solution is given in a dose of 0.5 mg/kg. (A 1% lidocaine solution is diluted threefold with normal saline to produce a 0.33% lidocaine solution.) The syringe containing the dilute anesthetic solution is then attached to the butterfly needle. The arm is exsanguinated either by elevating it for 3 to 4 minutes or by wrapping it carefully with an elastic bandage. A double pneumatic tourniquet is placed on the arm proximal to the fracture site. The more proximal of the two cuffs is inflated to 250 to 300 mm Hg. Within 1 minute after the injection, the patient usually experiences significant relief of pain. Mottling of the skin is another indication that the block is effective.
If tourniquet pain develops before the procedure is completed, the distal cuff of the tourniquet can be inflated and the proximal cuff released; because the area under the now inflated distal cuff is anesthetized by the block, the tourniquet can remain inflated longer without causing discomfort. After 30 to 45 minutes, most of the lidocaine has been bound to tissues in the forearm; therefore, removing the tourniquet at this time does not release a large dose of lidocaine into the general circulation. When the tourniquet is released, however, the patient’s pulse and respirations must be monitored because cardiac arrhythmias and seizures have occurred in some patients. A conservative practice is to maintain the tourniquet for 45 minutes (20 minutes has been used routinely as a minimum time), then release it slowly while monitoring vital signs. Moderately long- acting local anesthesia is required for postprocedural pain relief and is given locally around the site of fracture or surgery before discontinuing the Bier block.
Digital Block And Local Anesthesia
For smaller procedures in the fingers distal to the metacarpophalangeal joints a digital block gives excellent anesthesia and is easily administered. A dorsal approach to the web space is made with the needle, and a bolus of 1 to 2 mL of 1% to 2% lidocaine is placed under the skin as the needle is placed more volar, down to the subcutaneous layers bathing the neurovascular bundle.
Through the same insertion site, the needle is passed across dorsally, subcutaneously infiltrating another 1 to 2 mL until the next web space. A new insertion site is then made in the already anesthetized web space on the other side of the finger, dispensing another 1 to 2 mL of lidocaine down to the volar neurovascular bundle. Local anesthesia placed subcutaneously can be used for small procedures directly over the site of incision.
Joint And Tendon Sheath Injections
It is very common for patients suffering from arthritis or tendonitis to require an injection of corticosteroid as an anti-inflammatory agent. These injections are typically given in a mixture with local anesthetic to ease the discomfort during the postinjection phase.