Microsurgery: Transplantation and Replantation by Harry J. Buncke, MD, et al.
  Table of Contents / Chapter 39:
Anesthesia for Microsurgery
  1. The interscalene block is most useful for shoulder and proximal upper extremity surgery. When it is used for hand surgery, large volumes of local anesthetic are needed, increasing the risk of a toxic reaction. Even with a larger dose of anesthetic, the ulnar distribution is difficult to block. The advantages of this block are rapid onset of anesthesia in the shoulder and upper arm and a low incidence of pneumothorax. Complications include vertebral artery puncture and possible injection, causing immediate convulsion; intrathecal injection into a dural cuff, causing a total spinal and thoracic duct puncture with left-sided blocks. Frequently, the stellate ganglion, phrenic nerve, or recurrent laryngeal nerves are blocked, and the patient should be told of symptoms that may occur from such blocks. The interscalene block is amenable to a continuous technique by the insertion of an angiocath into the sheath.

2. Superclavicular block of the brachial plexus has long been used for upper extremity surgery, but it is less common now. The risk of pneumothorax is greatest with this brachial plexus block. The instance of complications is reported to be from 0.5% to 10%.17,20 The advantage of this technique is that a relatively small volume of anesthetic provides rapid onset of excellent anesthesia of the upper extremity except for the shoulder and the distribution of the intercostobrachial nerve. As with the interscalene technique, the anesthetic may spread to block the stellate ganglion and the phrenic or the recurrent laryngeal nerves.


3. Axillary block of the brachial plexus was described first in 1911, but it was not until the studies of Delong,19 Erikkson,20 and several others during the 1960s that it gained widespread use. It rapidly became popular for surgery distal to the elbow because it is easily performed and has relatively few complications, making it the safest of the brachial plexus blocks. This block does, however, have some limitations. For this block to be performed, the patient must be able to abduct the arm. Large volumes of anesthetic solution are needed for upper arm or shoulder anesthesia, and the proximal spread is unpredictable. The musculocutaneous nerve is sometimes missed because it leaves the sheath proximal to the site of injection, thus leaving the radial side of the forearm unanesthetized. Nevertheless, the continuous axillary block is useful in microsurgery for intraoperative anesthesia and for postoperative pain relief; it also provides a continuous sympathetic block. It is probably the most common type of regional anesthetic currently used in microsurgery. One must carefully secure the catheter in position with a suture or dressing so that it cannot be easily dislodged. Injections of local anesthetic can be made intermittently or continuously with the use of a volume pump. The catheter may be left in place for several days with no apparent problems.

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