Introduction
With the developments of the last three decades, outpatient surgery now constitutes more than 60% of surgery performed in most medical centers in the United States. It has initiated major revisions in the approach to anesthetic management and has been supported by the development of new drugs and techniques. Outpatient anesthesia requires more rapid recovery and a faster return to full mental function than standard inpatient procedures. It also requires minimum nausea, vomiting, and postoperative pain that might otherwise delay hospital discharge or precipitate unplanned overnight admission. The emphasis on home discharge has also elevated the patient’s perception of “satisfactory” anesthesia, which now includes a greater emphasis on alertness, a sense of well-being, and adequate pain relief at home without disabling side effects. Fortunately, new general anesthetic agents meet many of these requirements, especially rapid induction and emergence, which will theoretically improve the turnover in ambulatory surgery units.
Local anesthesia for the performance of surgery is ideal. Local anesthetics cause no loss of consciousness and provide excellent residual postoperative analgesia. This combination makes local anesthetic agents attractive options for outpatient surgery, where rapid discharge with minimal nausea and sedation is important to health care providers and patients. Regional anesthesia has been shown in some series to provide the same advantages, but meta-analysis of published series fails to show accelerated discharge despite better analgesia and nausea control. Neuraxial (spinal and epidural) techniques have also been advocated because of their rapid onset of dense anesthesia, but they also do not improve discharge and, like peripheral nerve blocks, require additional time for performance. Neuraxial approaches also require resolution of the block before a patient can walk, and they obviously require an alternative method of postoperative analgesia. There is also the issue of the potential for postspinal headaches and, more recently, transient neurologic symptoms (TNS) after spinal anesthesia.
Thus, although there are several advantages to regional techniques, it is legitimate to question whether regional anesthetic techniques are appropriate in the outpatient setting.
Options
Major options available in outpatient anesthesia are local, general, and regional techniques. For the sake of focus, this chapter will not include a discussion of local infiltration anesthesia techniques because these have universally been shown to be ideal techniques in outpatient anesthesia. This includes the use of local anesthesia for retrobulbar, peribulbar, or topical anesthesia for cataract surgery, which has been associated with a low risk of morbidity and with rapid discharge and high satisfaction in the elderly high-risk patient group undergoing this operation. Local techniques are also excellent for other superficial surgeries, such as hernia repair, breast biopsy, and perianal procedures.
General anesthesia is the most frequently used alternative, primarily because of the newer drugs available. The introduction of rapid-induction and fast-emergence general anesthetic agents (i.e., sevoflurane, desflurane, and propofol) in the last 30 years has produced dramatic improvement in the early emergence from general anesthesia. These advantages are balanced by side effects. The absence of analgesia in the postoperative period necessitates the addition of opioids and their attendant mental obtundation and nausea. The inhalational agents themselves continue to be associated with a 20% to 50% risk of postoperative nausea and vomiting, although this can be minimized by generous use of prophylactic medication. Propofol appears to be associated with a lower frequency of this complication but requires greater resources to administer and is no less expensive than the volatile drugs.
The regional techniques offer a third alternative, also with advantages and drawbacks. The two major categories are peripheral nerve blockade (PNB) and neuraxial blockade (NAB). Continuous peripheral nerve catheters (CPNB) have emerged as a third application. There are multiple reports of PNB, including intravenous regional anesthesia of the upper and lower extremities, as well as specific nerve blocks of the brachial and lumbar plexus (summarized in the recent meta-analysis ). They require a somewhat longer time to perform and a longer time for initiation of adequate anesthesia than either general anesthesia or the neuraxial techniques. NAB includes the use of spinal as well as epidural and caudal injection. Caudal anesthesia is primarily limited to pediatric practice, where it is usually performed as an adjunct to a general anesthetic in this patient population. Spinal anesthesia should be the most effective example of regional techniques in the outpatient setting because of its simplicity of performance and rapidity of onset but may be limited by prolonged discharge times.
Evidence
Most of the reports of regional techniques for outpatients are from enthusiastic supporters and usually do not include a comparative general anesthesia group. These reports are positive in their descriptions of analgesia, discharge times, and patient satisfaction. Although randomized blinded comparative studies are more desirable, it is impossible to perform a “blinded” study comparing the two because even the most naive of observers would be able to distinguish the presence of a local anesthetic block from a general anesthetic. It is also difficult to successfully randomly assign patients to different techniques for many procedures and many patient populations. Nevertheless, the literature search and meta-analysis already mentioned reviewed 15 studies comparing general anesthesia with NAB ( Table 51-1 ) and seven comparing PNB with general anesthesia ( Table 51-2 ). These studies support the use of regional techniques when compared with general anesthesia in terms of superior analgesia and reduced nausea but raise concerns about the time involved and the impact on significant outcomes such as discharge time ( Table 51-3 ).
| Outcome | Number of Trials | Neuraxial (Mean) | General (Mean) | Odds Ratio or WMD (95% CI) |
|---|---|---|---|---|
| Induction time (min) | 7 | 17.8 | 7.8 | 8.1 (4.1 to 12.1) † |
| PACU time (min) | 10 | 56.1 | 51.9 | 0.42 (–7.1 to 7.9) |
| VAS in PACU | 7 | 12.7 | 24.4 | –9 (–15.5 to –2.6) * |
| Nausea | 12 | 5% | 14.7% | 0.40 (0.15 to 1.06) |
| Phase 1 bypass | 4 | 30.8% | 13.5% | 5.4 (0.6 to 53.6) |
| Need for analgesia | 11 | 31% | 56% | 0.32 (0.18 to 0.57) † |
| ASU discharge time (min) | 14 | 190 | 153 | 34.6 (13 to 56.1) * |
| Patient satisfaction | 11 | 81% | 78% | 1.5 (0.8 to 23.1) |
| Outcome | Number of Trials | Nerve Block (Mean) | General (Mean) | Odds Ratio or WMD (95% CI) |
|---|---|---|---|---|
| Induction time (min) | 6 | 19.6 | 8.8 | 8.1 (2.6 to 13.7) * |
| PACU time (min) | 6 | 45.2 | 72 | –24.3 (–36.3 to –12) * |
| VAS in PACU | 7 | 9.6 | 35.8 | –24.5 (–35.7 to –13.3) * |
| Nausea | 6 | 6.8% | 30% | 0.17 (0.08 to 0.33) * |
| Phase 1 bypass | 6 | 81% | 315 | 14.3 (7.5 to 27.4) * |
| Need for analgesia | 6 | 6.2% | 42.3% | 0.11 (0.03 to 0.43) * |
| ASU discharge time (min) | 6 | 133.3 | 159.1 | –29.7 (–75.3 to 15.8) |
| Patient satisfaction | 4 | 88% | 72% | 4.7 (1.8 to 12) * |
| Neuraxial Block | Peripheral Nerve Block | |
|---|---|---|
| Induction time | Increased | Increased |
| PACU time | Same | Reduced |
| PACU VAS | Reduced | Reduced |
| Nausea | Same | Decreased |
| Phase 1 bypass | Same | Increased |
| Need for analgesics | Reduced | Reduced |
| ASU discharge time | Prolonged | Same |
| Patient satisfaction | Same | Greater |
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