• Karen C. Nielsen, MD
• Marcy S. Tucker, MD
• Susan M. Steele, MD

        GENERAL CONSIDERATIONS AND BRIEF HISTORY: ADVANTAGES OF NERVE BLOCKS IN AMBULATORY SURGERY

The development of ambulatory surgery and that of peripheral nerve blocks (PNBs) occurred over two separate historic timelines. The performance of outpatient or ambulatory surgeries commenced in the mid-1800s, and its utilization rapidly escalated throughout the next century. By 1980, 16.3% of all surgeries were performed on an outpatient basis. By 1984 this number rose to 30% and the Society for Ambulatory Anesthesia (SAMBA) was born. The total outpatient rate approached 50% by 1990, 60% in 1997, and may have hit 70% in 2003.^1,2 During the same span of time, techniques for PNBs were also being discovered. The decades from 1884, (when Koller and Brettauer first instilled ocular cocaine in Heidelberg, Germany³) to 1912 and 1914, (when Kappis and Heidenhein described the interscalene block,⁴) marked the birth of PNBs. Despite the coexistence of both ambulatory anesthesia and PNB techniques for over a century, they were not typically used concurrently.

        As ambulatory surgery acquired today’s popularity and widespread use, the scope of surgical procedures similarly expanded to become more invasive and pain-inducing. Suddenly, physicians were faced with a dual challenge: provide short-acting anesthesia thus achieving home-readiness within hours of surgery, concurrent with long-acting postoperative analgesia permitting the patient to remain discharged to the home environment. The differences between these dual desires have proven irreconcilable with modern opiate analgesia. This has been recently documented by Apfelbaum and colleagues, who quantified the shortcomings of ambulatory analgesic regimens. They found that 78% of those queried had felt pain of moderate (52%), severe (22%) or extreme (7%) intensity.⁵

        In response to ambulatory anesthesia’s dilemma, PNB techniques offer solutions ideal for an outpatient anesthetic: site-specific surgical anesthesia and a decreased dependency on general anesthesia (GA). In so doing, PNBs buffer the response to surgical stress, better maintain functional residual capacity, defend against loss of immunologic function, and avoid or shorten the period of postoperative ileus.⁶ By providing effective analgesia, PNBs can reduce patient exposure to opioids and their side effects. This allows for a more rapid discharge of satisfied patients to their home environment, resulting in cost savings for the ambulatory surgery center. As a cornerstone of multimodal analgesia, PNBs with long-acting local anesthetic (LA) help reduce patient readmission for pain or other side effects. Extending the effect of LA through continuous peripheral nerve blocks (CPNBs) further lengthens the period of low side-effect postoperative analgesia in the home environment.

        Despite the advances in PNBs and CPNBs, these techniques remain underutilized skills in ambulatory anesthesia. As recently as the year 2000, Dexter and Macario⁷ revealed that ambulatory surgeries utilized regional anesthesia in only 8% of cases. A 1997 survey by Hadzic and coworkers found that although 98% of anesthesiologists used some regional techniques, less than half of respondents placed at least five PNBs per month.⁸ A 2001 survey by Klein and colleagues concurred that although interscalene, axillary, and ankle blocks were performed more often, major conduction PNBs of the lower extremity were not commonly employed. Further analysis indicated that 85% of anesthesiologists discharged patients with long-acting PNBs of the three aforementioned types, but only 36% were willing to place a long-acting femoral nerve block. Many factors contribute to avoidance of long-lasting PNBs including fear of patient injury or self-care deficits at home, logistical issues related to the time needed for performance and onset of the PNB, as well as unfamiliarity with techniques.⁹ Concerns regarding unfamiliarity with techniques will persist as long as inadequacies exist in resident education.^10–12 But the issues of perceived outcome benefits versus risks, time required for PNB performance, and PNB reliability will likely remain the deciding factors in its use for outpatients. Regardless of the reason, the result remains the same: outpatient PNB remains a vastly underutilized technique. The real history of PNB and ambulatory surgery remains to be written.

Clinical Pearls

        PATIENT SELECTION

Several factors, both negative and positive, aid the anesthesiologist in excluding or selecting an ambulatory patient for a nerve block. The primary absolute negative factor is patient refusal of PNB. Assuming acceptance of the technique however, patient selection depends on benefits outweighing the risks to patient safety during placement of the block and, secondarily, on patient safety after discharge with an insensate extremity. Primary patient exclusion begins with a stated allergy to LA. Another reason to reconsider PNBs involves deep or noncompressible nerve block sites in a sufficiently anticoagulated patient. Although central neuraxial blockade can certainly be used in patients receiving a variety of anticoagulants,¹³ the rules governing its use are likely too stringent to be applied to all PNB techniques. If a patient can accept the traumatic risk of an elective direct laryngoscopy, they can likely also weather the risk of a femoral nerve block from an experienced operator.

        Immunologic concerns warrant exclusion if an infection is present at the nerve block site. Patients with sever pulmonary disease are not often scheduled to have procedures in an ambulatory facility, however, moderate to severe chronic obstructive pulmonary disease (COPD) in a patient warrants cautious consideration prior to selection of paravertebral block (PVB) or brachial plexus blockade. Although PNB techniques offer potential benefits over GA and narcotic analgesia, the consequences of pneumothorax and phrenic nerve paralysis must be weighed cautiously. Another screening consideration surrounds the patient with nerve injury. This is especially true in patients with either a worsening or improving nerve deficit that is under consideration for blockade. Although the literature provides no evidence that administration of PNBs in patients with preexisting neuropathy carries a risk of worsening the neurologic deficit, the complexity of the management and neurologic follow-up of these patients may outweigh the benefits of nerve blocks. Central nervous lesions can also cause anxiety in the consideration of peripheral block. Some advocate steering clear of patients with fluctuating central lesions like multiple sclerosis to avoid perceived liability surrounding the patient’s natural disease progression; these opinions are not substantiated in the literature, however. The final consideration of acute risks versus benefits applies not to patient physiology, but to the environment in which the PNB is placed. If it is to occur outside of the operating room, standard American Society of Anesthesiology monitors, suction, oxygen and resuscitative gear and medicines are required. More information on application of regional anesthesia in patients with coexisting disease can be found in Part VIII of this textbook (Regional Anesthesia in Patients with Special Considerations).

        After excluding patients in whom the immediate risks outweigh potential benefits of PNBs, concerns still remain regarding patient safety after discharge home with an insensate extremity. However, concerns of rendering the patients immobile in their home environment can be abated by the well-developed social support network that usually surrounds this subset of patients. In sharp contrast to these patients would be the patient with a weak nonoperative leg who has received a lower extremity block. Lower extremity block must also be carefully weighed in the morbidly obese, the frail elderly, and the patient with Parkinson disease because they are at a higher risk of falling. Postoperative surgical issues occasionally intrude on selection of long-duration PNB with the need for functional nerve assessment.

        Conversely, PNBs should be actively encouraged for patients about to undergo an invasive or extensive surgery on an extremity, such as open joint reconstruction or replacement, osteotomies, tendon transfers, fracture repair, or manipulation of arthrofibrosis. PNBs should also be sought for patients with chronic pain conditions and opioid tolerance to aid them in management of postoperative pain. Patients with complex regional pain syndrome (CRPS) have demonstrated a pattern of abnormal nerve healing and are prone to redevelopment of CRPS in the operative extremity. Regional anesthesia has been shown to be beneficial in preventing a recurrence when clonidine is used with intravenous regional anesthesia (IVRA) or when the most proximal and sympatholytic PNB is employed.^14,15 PNBs can also be of great benefit for patients undergoing surgeries that are particularly emetogenic, such as mastectomy, or for those with histories of postoperative nausea and vomiting (PONV) or opioid intolerance. Long-acting or continuous PNBs can also help patients avoid other side effects of opioids. Respiratory depression can be avoided in the COPD patient, and ileus or constipation can be limited after herniorrhaphy. Regional anesthesia (RA) can help prevent the need for airway manipulation in patients with asthma. PNBs can reduce surgical blood loss,¹⁶ assuaging concerns of the anemic or Jehovah’s Witness patient. A final (and controversial) benefit also exists in using PNB to help the anesthesiologist sidestep the issue of an anticipated difficult airway.

Clinical Pearls

        TECHNIQUE SELECTION

Interscalene Brachial Plexus Block

Interscalene PNB anesthetizes the brachial plexus, typically at the C6 nerve root. The popularity of this block relates to its utility in providing long-lasting analgesia after painful ambulatory orthopedic shoulder surgery. When Hadzic¹⁷ compared interscalene block to GA in 50 patients for outpatient rotator cuff surgery, he found that patients with PNB had more frequent postanesthesia care unit (PACU) bypass (76% vs 16%), suffered less pain, ambulated earlier, met discharge criteria sooner (123 min vs 286 min), had fewer unplanned réadmissions (0 vs 16%), and were more satisfied with their care. Brown coworkers¹⁸ found similar results and fewer postoperative side effects after interscalene block versus GA (pain 14% vs 45%, PONV 8% vs 43%, urinary retention 0% vs 25%, hospital admissions 17% vs 48%). In a large retrospective review comparing interscalene block with GA, D’Alessio and colleagues¹⁹ further demonstrated reductions in nonsurgical intraoperative time (29 ± 9 min vs 49 ± 12 min) and PACU time (72 ± 24 min vs 102 ± 40 min), as well as decreased anesthetic side effects in PACU.

        Al-Kaisy’s group²⁰ prospectively compared interscalene block with 10 mL 0.125% bupivacaine against placebo for outpatient shoulder arthroscopy done under GA. They found decreased pain and morphine use (2.7 ± 2.6 mg vs 9.5 ± 5.2 mg) during the PACU stay and a faster achievement of discharge criteria (139 ± 34 min vs 193 ± 59 min) with the nerve block. They also noted no difference between patient groups in their 24-h opioid use following PNB resolution at 2 h. In a similar study, Laurila and associates²¹ compared a low-volume interscalene block with a subacromial bursa block and placebo. They also found the interscalene block to be the most effective for early postoperative pain control.

        Singelyn and coworkers²² compared patients undergoing arthroscopic acromioplasty with interscalene PNB, isolated suprascapular nerve block, intraarticular LA, or systemic opioids. They concluded that interscalene PNB was most proficient, that suprascapular block was an alternative option, but that intraarticular LA injection offered no benefit to intravenous (IV) opioids.

        Failure to achieve surgical anesthesia with interscalene PNB ranges from 0 to 9.5%,^18–20,23 requiring conversion of 16% of cases to GA.¹⁸ Although side effects often include shortness of breath, dysphonia, and Horner’s syndrome^18,24 they rarely thwart discharge planning. More importantly, studies on inpatients have demonstrated a low risk of neurologic injury. In a series of 520 patients having single-injection or continuous interscalene block, Borgeat and colleagues²⁵ found that 14% had paresthesia, dysesthesia, or nonsurgical pain 10 days after surgery. The majority of these symptoms gradually resolved, leaving only one patient symptomatic with a plexus injury 9 months after surgery. The combination of an efficacious PNB, its relatively benign clinical application, and demonstrated benefits compared with GA ensure ongoing use of the interscalene block.

Clinical Pearls

Supraclavicular Brachial Plexus Block

        The supraclavicular PNB approaches the brachial plexus trunks between the clavicle and the first rib. Due to the close proximity of the trunks at this level and the close apposition of the surrounding fascia, the supraclavicular block can provide more reliable anesthesia with faster onset distal to the shoulder than the axillary approach. Bedder and associates²⁶ showed that supraclavicular block using 0.5% bupivacaine provided onset of sensory anesthesia in 4.0 ± 1.2 min and peak effect in 17.7 ±1.8 min. Consequently, supraclavicular block is ideal for rapid-turnover outpatient procedures of the elbow, wrist, and hand. Because the axillary nerve may be spared with this PNB, supraclavicular block is not always reliable for shoulder surgeries.²⁷ With the supraclavicular block, the needle insertion site is near the dome of the lung. Anecdotal reports have associated the “plumb- bob” technique with an unacceptably high risk of pneumothorax, leading many practitioners to avoid this block. Nevertheless, no study supports this concern or warrants prolonged observation of a patient after an uneventful anesthetic and recovery. To the contrary, Franco and Vieira²⁸ demonstrated the safety of supraclavicúlar PNB in a series of 1001 patients anesthetized by both consultants and residents. Touting a clinical efficacy of 97.2%, no major complications were reported. These data highlight the potential usefulness and safety profile of this as yet underutilized technique.

Clinical Pearls

Infraclavicular Brachial Plexus Block

Infraclavicular PNB is approached at the division and cord level of the brachial plexus. PNB at this level provides anesthesia appropriate for procedures done on the mid to distal upper extremity. As with supraclavicular PNB, this block has a high success rate and a low risk of pneumothorax.^29–31

        Hadzic and coworkers³² contrasted patients who underwent ambulatory wrist surgery with GA with those who received infraclavicular PNB. As a group, those patients with GA had lower PACU bypass rates (24% vs 76%), higher rates of PONV (32% vs 8%), and more numerous requests for analgesia (48% vs 0%). Fewer patients in the infraclavicular group reported inability to concentrate in the PACU (8% vs 56%), though statistical significance was lost by the time that discharge criteria were met. Although the infraclavicular block performed in the operating room prolonged induction by 5 min, total operative time was similar to GA. Discharge criteria were met more quickly in the PNB group (100 ± 44 min vs 203 ±91 min), and opioid use was similar in both groups over the first 48 h.

        Desroches³³ used infraclavicular PNB to achieve surgical anesthesia in 91% of outpatients and required 7 min or less for block execution. The risk of pneumothorax remained low at 0.7%, although published rates of vascular puncture can be as high as 17%.³⁴ The newer techniques with needle redirection laterally should reduce the risk of pneumothorax to practically negligible.

Clinical Pearls

Axillary Brachial Plexus Block

The brachial pulse allows for facile location of the axillary artery and the common sheath that invests the branches of the brachial plexus. This reliable landmark, the low risk of pneumothorax, and the usefulness of this PNB for surgical anesthesia of the mid to distal upper extremity has helped to make the axillary block the most popular PNB in the United States.^8,9 Axillary PNB can be successfully executed with a nerve stimulator, paresthesia, or the transarterial technique.

        Septa within the fascial sheath^35,36 may limit the rate of diffusion of LA to terminal nerves and result in individual nerve sparing. This can in turn lead to nerve sparing as well as delayed anesthetic set-up. In an attempt to overcome this problem, the stimulation and injection of individual nerves has been studied.³⁷ Bouaziz and associates³⁸ attempted to make an additional improvement in outcome by utilizing 0.5% bupivacaine to anesthetize the ulnar and median nerves and 2% lidocaine for the others. This strategy resulted in long-lasting anesthesia of a palmar incision with faster recovery of the remaining arm. Koscielniak-Nielsen and coworkers³⁹ investigated success and patient perceptions using multiple-stimulation in unmedicated outpatients. They found that electrolocation was uncomfortable for 80%, but that 98% would have the same technique in the future. Thirteen percent would request sedation in the future, and 95% were comfortable being discharged with an insensate extremity. Despite this success, although block performance only took an average of 9.8 min, block onset took an additional 23 min using a 1:1 mixture of 0.75% ropivacaine and 2% mepivacaine. Utilization of a preoperative “block room” can eliminate the delay of LA set-up, decrease nonsurgical operating room time, and improve overall efficiency.^40,41

        Outpatient axillary PNB is not without the risk of block failure or complication. Davis and colleagues⁴² reviewed 530 such blocks and found a 7% incidence of block failure requiring GA and a 2 % incidence of inadequate postoperative analgesia requiring admission. Complications were rare, with a less than 1% incidence of LA toxicity and no persistent neurologic deficits. Cooper’s group⁴³ reviewed the anesthetics of 1149 outpatients and found that 93% of those who responded would have an axillary block in the future. Those who were reluctant to have another block were more likely to have experienced any side effect (ie, bruising or pain in the axilla).

        Chan and coworkers⁴⁴ prospectively compared axillary block with IVRA and GA in 126 individuals having outpatient hand surgery. The RA groups required less opioids and had a decreased incidence of PONV (p < 0.05). But the induction time, overall discharge time, and cost were least in the IVRA group (p < 0.05).

Clinical Pearls

Iliohypogastric-Ilioinguinal Nerve Block

The iliohypogastric (T12, LI) and ilioinguinal (LI) nerves provide sensory innervation to the inferior abdomen and buttocks, the superomedial thigh, and part of the external genitalia. Block of these nerves is easily and efficiently performed 2 cm medial and 2 cm superior to the anterior superior iliac spine. Alternatively, the surgeon can apply LA to the nerves directly during an inguinal hernia repair. In the literature, the iliohypogastric-ilioinguinal nerve block has been used successfully as an adjunct to GA in surgeries such as inguinal herniorrhaphy and varicocelectomy.⁴⁵ When compared with placebo,⁴⁶ local wound infiltration,⁴⁷ subarachnoid block (SAB),⁴⁸ or GA alone,⁴⁸ ilioinguinal-iliohypogastric nerve block has been associated with decreases in postoperative pain scores,^46–48 postoperative opioid requirements,^46,47 PONV,⁴⁸ cost,⁴⁸ and discharge times.⁴⁸ Complications with this nerve block are usually related to the proximity of these nerves to the femoral nerve. Inadvertent femoral nerve block^49,50 can result in difficulty with ambulation and may be difficult to differentiate from direct surgical trauma to the nerve. Overall, although data demonstrate its usefulness as an adjunct for hernia surgery, the magnitude of benefit seen may not support its routine use when compared with the simple alternative of surgical wound infiltration and multimodal analgesia.

Clinical Pearls

Lumbar Plexus Block

The lumbar plexus block anesthetizes the femoral, obturator, and lateral femoral cutaneous nerves more reliably than more distal approaches to the femoral nerve.⁵¹ Although lumbar plexus block is useful for procedures that range from hip⁵² to knee^53–55 arthroplasty, the expansiveness of this block may be disadvantageous to outpatients unless a short-acting local anesthetic is used (eg, chloroprocaine). Loss of iliopsoas muscle function prevents flexion at the hip and increases the difficulty of ambulating with crutches or even a walker. Furthermore, there exists a risk of epidural spread of LA, ranging between 1.8% to 8.9%.^56,57 This may be caused by injecting LA too medially after eliciting the muscular response of a single nerve root. Such a mishap may prevent a patient from walking and delay discharge when long-acting local anesthetics are used.

        Knee arthroscopy remains a commonly performed ambulatory surgical procedure for which lumbar plexus PNB may be useful. Two randomized prospective trials compared lumbar plexus PNB with SAB or GA for this procedure. Jankowski and associates⁵⁸ found that more than twice the number of GA patients (45%) required analgesics in PACU versus those who received lumbar plexus PNB (21%) or SAB (14%). Although pain scores were higher at all points in the GA group, because mean scores were low even in this group they questioned whether lumbar plexus block was really necessary for this procedure. Hadzic and coworkers⁵⁹ presented compelling support for a lumbar plexus block and sciatic nerve block over GA for knee arthroscopy. By utilizing lumbar plexus and sciatic PNBs they were able to decrease severe PONV from 62% to 12%, odynophagia from 60% to 28% and time to achieve discharge criteria from 205 ± 94 min to 131 ± 62 min. The percent achieving PACU bypass increased with PNBs from 24% to 72%. Although PNBs (placed in the operating room) lengthened the time required for induction by 7 min, there was no overall increase in length of time spent in the operating room.

Clinical Pearls

Related posts:

Regional Anesthesia in the Patient with Preexisting Neurologic Disease. The History of Local Anesthesia. Stimulating Catheters. Ultrasound-Assisted Nerve Blocks in Adults. Cutaneous Blocks for the Upper Extremity. Cervical Plexus Block.

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