New developments in spinal anesthesia.

Spinal anesthesia can be used effectively and efficiently for a variety of cases in both the inpatient and the ambulatory surgery setting. Choice of agent, dose, distribution, use of adjuncts, and occasionally the use of continuous spinal anesthesia can tailor the spinal anesthetic to a specific type and duration of surgery. Although spinal anesthesia is extremely safe, adherence of new guidelines for patients receiving anticoagulant drugs, LMWH in particular, may minimize the risk of neurologic injury from spinal bleeding. At present, intrathecal adjuncts, such as neostigmine and clonidine used with local anesthetics, have shown limited usefulness, whereas lipophilic opioids, such as fentanyl, appear to increase duration and quality of spinal block without increasing the time to recovery. In the future, shorter-acting local anesthetics, possibly in conjunction with continuous catheter technologies, may reduce recovery times after spinal anesthesia without increasing risk. Spinal agents with long-acting analgesic properties that do not produce sensorimotor deficits may go beyond the immediate perioperative period and relieve postoperative pain. Currently there is controversy surrounding the use of spinal lidocaine and the occurrence of TNS, especially in the outpatient setting. The prudent use of small-dose bupivacaine and possibly procaine may reduce this risk, further supporting the use of spinal anesthesia for ambulatory as well as inpatient surgical procedures.