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Regional anesthesia can offer many advantages for the ambulatory patient population (see Chapter 43 Chapter 44 Chapter 45 ). In addition to limiting the anesthetized area to the surgical site, common side effects of general anesthesia (e.g., nausea, vomiting, dizziness, lethargy) can be avoided.[360] Furthermore, the need for postanesthesia nursing care is decreased if effective analgesia is provided in the early postoperative period.[361] [362] It has been suggested that regional anesthesia techniques are the most cost-effective in the outpatient setting because of the lower incidence of side effects and improved recovery in comparison to general anesthesia.[361] Proper patient selection along with the skill and enthusiasm of the surgical and anesthesia teams will allow an even wider variety of procedures to be performed with regional anesthetic techniques in the future. Another important factor to successful implementation of a regional anesthesia program for ambulatory surgery is the availability of an induction room to perform the block before the patient enters the operating room.[363]
Spinal anesthesia is the simplest and most reliable regional anesthetic technique. However, the incidence of side effects is surprisingly high when used in the ambulatory setting. The most troublesome complications of outpatient spinal anesthesia are residual effects of the block on motor, sensory, and sympathetic nervous system function, which can contribute to delayed ambulation, dizziness, urinary retention, and impaired balance.[364] In addition, post-dural puncture headache and backache remain problems after spinal anesthesia. Although the incidence of post-dural puncture headache can be minimized with the use of small-bore, 25-gauge, pencil-point needles, the incidence of failed blocks appears to be higher. [365] When compared with general anesthesia, the use of spinal anesthesia, even with small doses of short-acting local anesthetics, is associated with a high incidence of backache (35% versus 14%).[364] [366]
Short-acting local anesthetics (e.g., lidocaine and procaine) are preferable to bupivacaine and tetracaine in out-patients to ensure a more rapid recovery. However, the use of lidocaine is controversial because of numerous reports of transient neuropathic symptoms (i.e., radicular nerve root irritation).[367] [368] As a result, investigators are recommending the use of isobaric lidocaine, as well as combinations of small-dose hypobaric lidocaine combined with fentanyl or sufentanil. The addition of fentanyl (10 to 25 µg) prolongs sensory but not motor blockade and appears to decrease the time to voiding and full recovery.[369] In studies involving outpatients undergoing laparoscopy, a small-dose hypobaric solution of 1% lidocaine (20 to 25 mg) with fentanyl (25 µg) led to significantly faster recovery and less intraoperative hypotension than did 50 to 75 mg of hyperbaric lidocaine alone.[370] [371] [372] However, addition of the opioid analgesic increases the incidence of pruritus and PONV. Intrathecal fentanyl-induced pruritus is more severe with procaine than with lidocaine or bupivacaine. [373] Adjunctive use of droperidol (0.625 mg) or nalbuphine (4 mg), or both, can decrease these side effects.[374] Intrathecal bupivacaine should be reserved for ambulatory procedures with an anticipated duration of more than 2 hours because of its more prolonged recovery.[370] [375] [376] Outpatients should be allowed to recover motor function fully before discharge. After complete recovery of motor function, residual sympathetic blockade and orthostatic hypotension are less likely to be a problem on ambulation.[377] [378] However, functional balance may be impaired for 150 to 180 minutes after spinal anesthesia.[379]
Epidural anesthesia is technically more difficult to perform, it has a slower onset of action, the potential for intravascular or intrathecal injection exists, and it is associated with a greater chance of an incomplete sensory block than spinal anesthesia is. The use of 3% 2-chloroprocaine epidural anesthesia achieved discharge times comparable to those of small-dose lidocaine spinal anesthesia for outpatient knee arthroscopy while avoiding post-dural puncture headache and transient neurologic symptoms.[380] Another advantage of epidural anesthesia is the ability to extend the duration of anesthesia for procedures with a variable surgical time. Use of the short-acting local anesthetic 2-chloroprocaine for outpatient epidural anesthesia was associated with a high incidence of back pain from muscle spasm as a result of the preservative ethylenediaminetetraacetic acid (EDTA).[381] However, the newer formulations are preservative free and are associated with a discharge time comparable to that of general anesthesia.[382] Epidural 3% 2-chloroprocaine enables readiness for discharge home 1 hour sooner than 1.5% lidocaine does for knee arthroscopy.[383] The use of combined spinal-epidural anesthesia allows for the reliability of spinal anesthesia with the flexibility of continuous epidural anesthesia.[384] [385] [386] Patients receive an initial small dose of intrathecal local anesthetic with a needle-through-needle technique, and then an epidural catheter is placed. The small initial dose of intrathecal drug results in lower sensory levels, reduced side effects, and faster recovery from the sensory-motor blockade. If necessary, the epidural catheter could be used to extend the block beyond the duration of the spinal anesthetic.
For short superficial surgical procedures (<60 minutes) limited to a single extremity, the intravenous regional (Bier) block technique with 0.5% lidocaine is a simple and reliable technique (see Chapter 44 ). This procedure, which can be used for either upper or lower extremity
If more profound and prolonged anesthesia of the upper or lower extremity is required, a major regional block of the brachial plexus (e.g., axillary block or interscalene block) or femoral-popliteal nerves can be extremely valuable in the ambulatory setting (see Chapter 44 ).[392] [393] The "three-in-one block" (femoral, obturator, and lateral femoral cutaneous nerves) performed with the use of a perivascular technique is useful for outpatient knee arthroscopy and anterior cruciate ligament repairs because it provides excellent postoperative analgesia. Use of a simple femoral nerve block with 0.25% or 0.5% bupivacaine improves postoperative analgesia after arthroscopic anterior cruciate repairs.[393] Ankle blocks are also effective techniques for surgery on the foot. However, popliteal nerve blocks are simple to perform and provide excellent postoperative analgesia after foot and ankle surgery.[394] More importantly, these peripheral blocks can be extended by using continuous local anesthetic infusions.[395] [396]
A wide variety of continuous peripheral nerve blocks are being used for painful ambulatory surgery procedures.[397] [398] A continuous popliteal nerve block provides for improved analgesia, decreased opioid use, and greater patient satisfaction after painful foot and ankle procedures.[395] [396] After painful upper extremity procedures, a continuous brachial plexus perineural block was found to decrease not only pain and opioid usage but also sleep disturbances, and it improves patient satisfaction.[399] Continuous femoral nerve block provides more effective pain relief after anterior cruciate ligament repair than intra-articular analgesia does.[400] The use of disposable nonelectronic pumps may offer advances over mechanical pumps in the ambulatory setting.[401] Patient-controlled regional anesthesia has also been used effectively for pain control outside the hospital after hand surgery.[402]
Other popular peripheral nerve blocks include combined deep and superficial cervical plexus blocks, which reduces pain and opioid requirements after thyroid surgery.[403] When compared with intravenous regional and general anesthesia for carpal tunnel surgery, distal nerve blocks at the wrist were associated with improved intraoperative cardiovascular stability and earlier discharge.[404] Paravertebral somatic nerve blocks can be used as an alternative to ilioinguinal-hypogastric nerve block for inguinal herniorrhaphy.[405] However, the risk of serious side effects (e.g., pneumothorax) is a concern with paravertebral blocks.
In pediatric patients, peripheral nerve blocks can be performed immediately after induction of general anesthesia to reduce the anesthetic requirement and provide postoperative analgesia (see Chapter 45 ).[377] Historically, caudal anesthesia has been the most popular technique to reduce postoperative pain in children undergoing lower abdominal, perineal, and lower extremity procedures. However, this central neuraxis block is associated with more side effects and a longer recovery time than peripheral nerve blocks (e.g., dorsal penial nerve block).[406] Other popular regional anesthetic techniques for children include blockade of the ilioinguinal and iliohypogastric nerves to minimize postherniorrhaphy pain and use of the dorsal penial nerve block and subcutaneous ring block for postcircumcision pain.[406] [407] Interestingly, simple wound infiltration (or instillation) with local anesthetics may be as effective as a caudal or ilioinguinal nerve block in reducing pain after inguinal hernia repair.[408] Studies also suggest that systemic ketorolac (1 mg/kg) is as efficacious as caudal blockade and has a lower incidence of side effects when combined with local anesthetic infiltration. [409] Similarly, topical lidocaine ointment is an effective alternative to both a peripheral nerve block and opioid analgesics for postcircumcision pain.[410]
Of all the anesthetic techniques suitable for outpatients, local infiltration of the operative site with dilute solutions of local anesthetics may be the simplest and safest approach to reducing postoperative pain. Outpatient urologic procedures (e.g., vasovasostomy, orchiopexy, and hydrocele and spermatocele repairs) performed with local anesthesia can significantly decrease the overall cost.[20] Outpatient knee arthroscopy can also be performed under local anesthesia (e.g., 20 to 30 mL of 0.5% bupivacaine).[411] In addition, inguinal herniorrhaphy has been performed under local anesthesia, with excellent patient acceptance and minimal postoperative complications (e.g., urinary retention). [412] [413] A combination of local infiltration and intercostal nerve blocks has been used for lithotripsy. [414] Careful patient (and surgeon) selection is required for operations performed with local infiltration or a field block techniques. Local anesthetic supplementation during general and spinal anesthesia (e.g., infiltration with bupivacaine, 0.25% to 0.5%) will also decrease incisional pain in the postdischarge period.[415]
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