Medical Edge Newspaper Column

Type Of Surgical Anesthesia Is An Individual Matter

March 20, 2006
DEAR MAYO CLINIC:
What is the safest type of anesthesia for an older person undergoing knee-replacement surgery?

ANSWER:
While all common types of anesthesia are safe and effective when administered by properly trained individuals, none can be considered safest or most effective. Optimal selection depends on the patient's history, and communication between patient and anesthesiologist.

Knee-replacement surgery, also known as total knee arthroplasty, or TKA, can help relieve pain and restore function in severely diseased knee joints. In this procedure, a surgeon cuts away damaged bone and cartilage from your thighbone, shinbone, and kneecap, and inserts an artificial joint. Made of metal alloys, high-grade plastics and polymers, the prosthesis closely approximates your natural knee's ability to roll and glide as it bends.

More than 300,000 patients undergo TKA every year in the United States, and some 90 percent experience significant pain relief, improved mobility and a better overall quality of life as a result.

As with most other invasive surgeries, TKA requires anesthesia. Options include general anesthesia (the patient is put to sleep); regional anesthesia (numbing part of an awake patient's body); or a combination of the two.

General anesthesia typically involves the administration of an inhaled anesthetic gas along with intravenous pain medications, sedatives and muscle relaxants. When patients are anesthetized in this manner, their airways must be secured and protected by a breathing tube.

Regional anesthesia entails the administration of local anesthetics, which block the transmission of pain signals from the surgical site to the brain. One commonly used regional application is spinal anesthesia (injection of a local anesthetic into the cerebrospinal fluid, which is contained within the dura, the covering of the spinal cord and nerve roots). A second regional application in common use is epidural anesthesia (injection into the area -- the epidural space -- just outside the dura that surrounds the spinal cord). Both approaches are similar in their placement and ability to block sensations from the lower half of the body.

Another form of regional anesthesia rapidly gaining popularity is numbing the sensory nerves through peripheral nerve blocks (injection near the nerves) or through catheters placed next to the nerves. These regional blocks use local anesthetics that are extremely effective at preventing and alleviating postoperative pain and minimizing the side effects sometimes seen with narcotic pain relievers.

At Mayo Clinic, most patients scheduled for TKA currently receive peripheral blocks of the femoral and sciatic nerves, coupled with a general or spinal anesthetic. This combined technique has resulted in improved patient satisfaction, better pain reduction and a reduced stay in the hospital.

Although this combination has been very effective for the majority of our patients, no one approach is recommended for all. Patients must share their medical, surgical and anesthetic history with their anesthesiologist, so that an individualized anesthetic plan can be devised for their surgery. After discussion and careful thought, one patient may find that a general anesthetic is a more logical option, while another patient would likely have a better outcome with a regional anesthetic.

-- Michael J. Brown, M.D., Anesthesiology, Mayo Clinic, Rochester, Minn.