The criteria for outpatients receiving regional anesthesia remain the same as for other outpatient procedures, including the level of fitness and fasting status. The advantages of regional analgesia cannot be relied upon to avoid the recognized risks of preexisting medical conditions, such as obstructive sleep apnea. Although regional anesthesia may reduce the need for opioids in such patients, standard guidelines for monitoring and postoperative observation nevertheless must be observed (7). The indications and contraindications for regional techniques also remain the same: the presence of coagulopathy, infection, lack of cooperation, and neurologic disease must be considered. In addition, in the outpatient, significant obesity may increase the potential for block failure and complications (8), although these patients should not necessarily be excluded from consideration.

Patient educations remains a challenge in the outpatient setting. Ambulatory patients are frequently interviewed by the anesthesiologist only on the morning of surgery, and a detailed explanation of a regional technique and acceptance by the patient can consume precious time. Preferably, a preoperative evaluation can be scheduled in advance, or a phone call can at least initiate the educational process. Ideally, the surgeon will be an advocate of regional techniques and start the acceptance process during her preoperative counseling.

Standard American Society of Anesthesiologists (ASA) monitoring guidelines apply. As with all regional techniques, the smallest volume of the local anesthetic drug in a solution of the lowest possible concentration that will give the desired effect should be used. Because of the risk of toxicity, as well as the more common risk of respiratory depression from sedative medications, a dedicated observer trained in advanced life support must be available to monitor mental status, especially with local anesthesia and sedation provided by the surgeon.

Although rapport, gentleness, and skill in performing the block usually make premedication unnecessary, preoperative sedation for regional anesthesia may be appropriate. Midazolam, 1 to 2 mg, intravenously is an excellent asset to regional
anesthesia, often ablating the recall of unpleasant needle insertions or paresthesias. The sedative-amnestic effect can limit its usefulness if the patient becomes confused and can no longer cooperate with the anesthesiologist. Heavy sedation can also prolong time to discharge.

For uncomfortable procedures (which probably includes all multiple needle insertions), analgesia may be provided with a short-acting narcotic such as fentanyl (50 to 100 μg). Again, excessive doses are to be avoided because of the risk of respiratory depression and the potential for increased nausea and vomiting. Supplemental oxygen during the performance of blocks and during surgery is advisable. The short-acting analgesics alfentanil and remifentanil might be appealing, but their duration is too brief to be useful for the performance of most blocks.

If further intraoperative sedation is needed, an intravenous (IV) propofol infusion in doses of 25 to 50 μg/kg/min is useful.

In the outpatient setting, speed of room turnover and discharge are important considerations. Although the regional anesthetic techniques described here will allow more rapid discharge and enhanced analgesia, additional time is spent in performing blocks and in allowing adequate onset time of local anesthetic blockade. For the outpatient anesthesiologist, several modifications of choices are helpful.

The selection of rapid-onset blocks and drugs is helpful. In that regard, IV regional and spinal anesthesia techniques are particularly helpful. These can be performed in the operating room itself with little delay in the start of surgery and may be as efficient as general anesthesia itself (9). Selection of rapid-acting drugs, such as 2-chloroprocaine or lidocaine, also provides more rapid onset. Raising the pH of commercial local anesthetic solutions (by adding 1 mEq of sodium bicarbonate to each 10 mL of solution) has also been shown to speed onset of the intermediate duration amino amide local anesthetics for peripheral nerve blocks (10), although this remains controversial.

The optimal time-saver in outpatient surgery is the performance of a block in a location separate from the operating room (9,11). This can be a dedicated anesthesia induction room or a designated corner of the PACU. A separate location, with all of the necessary equipment, drugs, and monitors can allow undisturbed performance of the block and the start of the required “soak time” while the operating room is being prepared. Several investigators have shown that with such an arrangement, the “anesthesia-related time” in the operating room can actually be less than with a general anesthetic technique (12,13). Use of a separate area includes the potential to include additional personnel to aid in block performance. Although an additional anesthesia provider to give sedation and assistance is ideal, PACU nurses or technicians can also help with positioning, preparation of equipment, and manipulation of nerve stimulators or ultrasound devices.

Block technique also impacts efficiency. Selection of simpler techniques with easily identified landmarks (arteries, prominent bones, tendons) will be easier to initiate, and may have higher reliability than techniques that rely on complex geometric measurements and drawings. Similarly, nerve localization technique can improve speed. Electrical neural stimulation identifies nerves at a greater distance than paresthesia techniques, and the use of the more complex ultrasound may prove to be an even faster way to localize nerves and direct injection of the local anesthetic (14,15). The choice of technique must include the level of familiarity and comfort of the operator, since the learning of new approaches is always associated with increased time. All of these considerations should be included when modifying the approach to performing regional anesthesia in the outpatient setting.

Before discharge, the patient must meet standard discharge criteria for alertness and hemodynamic stability. This does not imply full recovery of a peripheral nerve blockade, since one of the advantages is the potential for discharge with effective residual analgesia. Multiple studies have confirmed the safety of discharging patients with anesthetized extremities (16). Careful instruction must be given in order to avoid injury. In addition, patients must be provided with an appropriate sling for the arm or crutches for the leg, or other protection for the numb extremity or anesthetized area. The usual outpatient precautions about an adult accompaniment home and for the first 24 hours also apply, and are even more essential for the patient with an immobile extremity.

Patients who have received epidural or spinal block must have full recovery of motor function before discharge. If all sensory anesthesia has regressed, particularly with a full return of perineal sensation, then sympathetic blockade and orthostatic hypotension should not be a problem on ambulation. Urinary retention is not a frequent problem with short-acting neuraxial techniques (17), but can occur in older males and in patients who have had operations with groin or perineal incisions. It is most frequently related to overdistention of the bladder during the period of sensory loss. If this overdistention goes beyond the usual cystometric capacity of the bladder, return of function is delayed. This most frequently happens with longer-acting spinal anesthetics such as bupivacaine or higher doses of lidocaine associated with the use of epinephrine. With low doses of lidocaine, very low doses of bupivacaine (5–6 mg), or the use of chloroprocaine, the frequency is similar to that associated with general anesthesia in the outpatient setting. If there is any uncertainty, the bladder volume can be assessed by physical examination or ultrasound, and simple catheter drainage performed if distention is present. Following this (or if no distention is present), most patients can be discharged home with instructions to return to the emergency room should problems develop later.

A delayed complication of spinal anesthesia is the potential for postdural puncture headache. This has occurred as often as 10% in previous reports, but has been significantly reduced by the use of smaller-gauge rounded-bevel needles in the last 15 years. The current literature suggests that the incidence is not greater than 2% in the outpatient setting, and may be considerably lower in patients over 40 years of age. One of the problems is that the symptoms do not usually occur until a day or so following discharge, and thus they may necessitate more complex management in the outpatient setting. Patients should all be advised of the potential symptoms of postdural puncture headache and be given clear instructions for follow-up contacts if these symptoms arise. The diagnosis and treatment are discussed elsewhere in this text, and are generally the same in the outpatient as for the inpatient. It is more problematic to require the outpatient to return to the hospital for therapy, and thus conservative measures are more frequently pursued for a longer period of time. The risk of this complication must be weighed against the definite advantages of the speed of onset of
spinal anesthesia, which makes it the most competitive regional anesthetic technique for use in an outpatient environment.

Postoperative and postdischarge analgesia are a challenge in the outpatient. Prolonged regional blockade is ideal, but most patients will also require some supplemental systemic analgesia. To avoid the side effects of opioids, a multimodal postoperative analgesia regimen should be planned for when the regional block resolves. Simple steps such as elevation, immobilization, and cold therapy are appropriate. Nonopioid analgesics should be the first addition. Acetaminophen is underutilized in the United States, but can provide an effective base of analgesia that reduces the need for opioid treatments. Nonsteroidal analgesics are also very effective, and often can be administered preoperatively to provide a preemptive reduction of analgesic needs (18). Intraoperative use of ketorolac has been shown to reduce narcotic requirements without producing nausea or respiratory depression. It is particularly effective in orthopedic and gynecologic procedures, although contraindicated in the presence of significant coagulopathy or renal disease. Doses of 30 mg IV (15 mg in elderly patients) are useful. The use of local infiltration with local anesthetics is another excellent alternative, especially effective in pediatric patients. Instillation of bupivacaine into knee joints following arthroscopy will also reduce narcotic requirements (19).

The most recent addition to the armamentarium of the outpatient anesthesiologist is the use of indwelling peripheral nerve catheters for home infusions after discharge (20). This technique requires more time for insertion, but fortunately is facilitated by the development of new needle/catheter combination sets and the use of stimulating catheters to ensure better localization. Ultrasound had also aided in nerve localization and catheter placement for these techniques. Multiple types of pumps are now available allowing flexibility in dose, patient control, and duration of therapy, and they are generally reliable in delivering the programmed doses (21). Securing the catheters has been a challenge in some locations (especially the neck), but the process of tunneling the catheter and using an occlusive dressing and adhesive has improved the success. Careful patient instruction and close follow-up are required, usually necessitating anesthesiologist availability 24 hours a day by phone. Concern about the potential of local anesthetic toxicity appears to be minimal when dilute concentrations of 0.2% ropivacaine or 0.125% bupivacaine are used. Removal of the catheters can be performed on follow-up visits to the surgeon’s office or outpatient center, but most patients are able to remove the catheters safely at home. Arrangements need to be made for recovery of the reusable pumps, or clear instructions about disposal of the disposable model pumps. Despite the added work required for this therapy, extensive experience has shown the reliability and relative safety of these techniques (22). Multiple studies have shown significant advantages in prolonged analgesia, particularly for the more painful orthopedic procedures of the upper and lower extremity, and greatly enhanced patient satisfaction (23).

Upper extremity surgery is frequently performed in the outpatient setting. Regional anesthetic techniques are especially suitable for outpatient upper extremity surgery because they have relatively rapid onset and do not limit ambulation at the time of discharge. Many of these blocks can be performed with a single-injection technique, and the nerves are relatively superficial, making it an easy application of regional technique for outpatients.

Arthroscopic shoulder surgery is one of the more commonly performed upper extremity surgeries in the outpatient setting. Interscalene brachial plexus blockade, with its inherently associated cervical plexus blockade, offers ideal anesthesia for shoulder procedures. Interscalene anesthesia has the advantage of being a single-injection technique, and is thus simple and rapid to perform. Interscalene blockade by itself is sufficient for many of the procedures performed on the shoulder, such as distal clavicle resection, subacromial decompression, and even rotator cuff repair. Insertion of posterior shoulder cannula ports can sometimes be uncomfortable for the patient and may need to be treated with supplemental injections of fentanyl or local anesthesia at the sites. Again, the use of intermediate-duration amino amides provides excellent anesthesia for most of the surgical procedures, as well as 4 to 6 hours of analgesia postoperatively. If longer analgesia is sought with the long-acting amino amides, often a corresponding delay in onset of blockade occurs. For prolonged analgesia, insertion of a continuous catheter is ideal, but again may require more preparation time. Interscalene catheters are especially prone to migration with neck movement, and tunneling and secure dressing is useful. In these situations, an induction room is especially useful (11). Although the interscalene block can be relied on for most surgeries, many practitioners (depending upon the specific traditions of their own operating room) may choose to provide additional supplemental analgesia with a propofol infusion and a laryngeal mask airway to ensure adequate ventilation in a patient who is frequently positioned and draped in a way that makes it difficult for the anesthesiologist to maintain contact with the airway intraoperatively. The use of this technique can also avoid the delay needed for onset of total anesthesia with the regional block, but allow a low dose of propofol and a fully alert and comfortable patient on arrival in PACU. If general anesthesia alone is used, the addition of a suprascapular nerve block at the end of the procedure will add significant
analgesia, allowing earlier discharge (32), but this is not useful if an interscalene has been performed (33).

Several investigators have shown significant advantages to the use of the interscalene technique for shoulder surgery, especially in providing early postoperative analgesia, freedom of nausea, increased PACU phase 1 bypass, and reduced overnight admission rates (13,34,35,36,37). Several investigators report decreased operating room times when their blocks were performed in an induction area (12,13,36). Most authors have used higher concentrations of long-acting amino amides, such as 0.5% bupivacaine or 0.5% or 0.75% ropivacaine to provide prolonged duration, but lower concentrations can produce less motor blockade, which might be more acceptable to patients (34,35). Unfortunately, with all of these regimens, the duration of analgesia is limited to 12 to 18 hours, and the benefits do not persist long after discharge (38).