Anesthesia for Hand Surgery
The goal of anesthesia for procedures involving the upper extremity is to provide the most comfortable and safe experience for the patient during surgery. Various options are available, each of which have particular benefits and risks. The decision regarding which anesthetic technique is chosen is dependent upon various factors, including the extent, site, and expected duration of surgery; need for sedation; general medical health of the patient, and personal preference, among others. The following is a brief discussion of various anesthetic techniques commonly utilized when performing surgery on the hand and wrist.
- Local anesthesia. The simplest anesthetic technique is to inject medications (local anesthetics) directly into the site where a procedure will be performed. This is commonly used for simple, small operations, which can be performed quickly. Advantages of local anesthesia include quick onset, minimal expense, and simplicity. In addition, a local anesthetic is most commonly administered by the surgeon, and there is no need for the services of an anesthesiologist. Disadvantages of local anesthesia include inability to anesthetize a large area, distortion of tissues from the local anesthetic substance, and discomfort and pain associated with use of a tourniquet. For select patients, local anesthesia can be administered along with intravenous sedatives provided by an anesthesiologist. This technique is beneficial for those patients who require sedation due to anxiety or a potential need for more prolonged surgical time.
- Hematoma block. A useful technique in providing anesthesia for the manipulation of certain fractures is called a “hematoma block.” This technique involves injecting anesthesia directly into the fracture site, where blood and fluid has accumulated. The local anesthetic mixes with the fluid (fracture hematoma) and numbs the ends of the bone. This technique allows for fracture manipulation and reduction to take place with minimal discomfort. Similar to local anesthesia, this procedure can be performed without sedation in an office, clinic, or outpatient surgical setting. Hematoma blocks are most commonly utilized for distal radius fractures.
- Regional anesthesia (nerve) blocks. Regional anesthesia utilizes medications to selectively block the sensory function of specific nerves in the extremities. There are a variety of regional anesthetic techniques, including digital blocks, wrist blocks, intravenous regional anesthetic blocks, and Axillary blocks.
- Digital blocks are a simple and quick method to anesthetize individual fingers and the thumb for many small procedures. With this technique, a local anesthetic is injected at the site where the two digital nerves enter the digits. Digital blocks can provide rapid anesthesia to select digits, which is useful for many simple office and outpatient surgical procedures.
- Wrist blocks are based upon the anatomy of the three nerves at the wrist level. The palmar surface of the thumb, index, middle, and radial-half of the ring finger are supplied by the median nerve, which enters the wrist through the carpal tunnel. The Ulnar nerve passes through Guyon’s tunnel, which boundaries are formed by the Hook of Hamate and Pisiform, two carpal bones on the medial or ulnar side of the wrist. The ulnar nerve supplies the medial side of the ring finger, and the little finger. Lastly, the radial nerve passes through the wrist in the subcutaneous tissue over the radial styloid. The radial nerve supplies sensation to the dorsal (or top) of the thumb, index, and (occasionally) middle finger. Local blocks can be given at the site where these three nerves enter the wrist to provide anesthesia for specific procedures in the hand and digits.
- Intravenous (IV) regional anesthesia is a technique whereby local anesthesia medication is injected into a vein, and then infiltrates out into the soft tissue to provide anesthesia to the whole arm. First, a needle is placed into a vein, and then the blood is removed from the extremity by use of a rubber bandage wrapped from the fingers to the upper arm. A tourniquet on the upper arm is then inflated, which prevents blood from refilling the venous system. Local anesthetic medication is then injected through the previously positioned needle into the empty vein, and the tourniquet then prevents it from getting into the rest of the body. The venous system of the arm becomes filled with the local anesthetic, which then slowly leaks out and numbs the extremity. This is a commonly used technique which provides anesthesia to the entire upper extremity for one to two hours. Intravenous regional anesthesia is commonly preferred for routine hand and wrist surgeries because it is well tolerated, safe, reliable, and has a rapid onset.
- Axillary block anesthesia is a technique which can also provide anesthesia to the whole arm. After the nerves exit the spinal cord, they connect from the Axillary (armpit) and upper arm to the forearm and hand. In the axillary area, local anesthetic medication is injected adjacent to the nerves, which blocks nerve function to the lower arm. This technique may provide adequate anesthesia for the entire upper extremity for several hours – allowing many complex surgical procedures to be performed. Axillary blocks are commonly used in providing lasting pain relief for many hours following extensive surgical procedures.
- General anesthesia is also utilized for many hand surgical procedures. Contemporary techniques are used to safely put the patient “to sleep,” often on an outpatient basis. General anesthesia requires an anesthesiologist and monitoring, and must be performed in a surgery center or hospital setting. Certain medical conditions may preclude the use of general anesthesia. For many patients, a preoperative evaluation by an internist or family doctor is beneficial in determining whether there are any medical factors which may place the patient at increased risk for general anesthesia.