The Journal of The New York School of Regional Anesthesia & Pain Medicine

Peripheral Nerve Blocks For Ambulatory Surgery Of The Lower Extremity

By: Admir Hadzic, M.D., Ph.D. & Jerry D. Vloka, M.D., Ph.D.

Since 1990s virtually all minor surgery and a substantial proportion of major surgery in the United States have been performed in hospital-affiliated, freestanding, and office-based ambulatory surgery units. While the surgical procedures are similar whether they are performed in the inpatient or outpatient setting, the anesthetic technique and nursing care are quite different. The majority of ambulatory surgery procedures are associated with a relatively minor surgical trauma. Thus the discharge of these patients to their homes is frequently limited by the time required to recover from anesthesia. The peripheral location of the surgical site in lower extremity surgery and the possibility to block the pain pathways at multiple levels, present a clear advantage for peripheral nerve blocks over either neuraxial or general anesthesia in ambulatory surgery setting. The use of specific nerve blocks provides anesthesia qualitatively comparable to that of spinal anesthesia [1, 2] but limited to the area of surgical interest. This obviates the need for general anesthesia or excessive sedation during surgery and eliminates the "wake-up" time, which coupled with postoperative analgesia facilitates early discharge homes.

Postoperative pain is one of the major challenges in ambulatory anesthesia practice.[3] It has been recently suggested that concerns about postoperative nausea and vomiting as well as prolonged sedation may lead anesthesiologists to underutilize opioids in surgical outpatients. This may lead to inadequate pain relief in the immediate postoperative period, which in turn may result in more pain and discomfort after discharge than in those patients whose pain was adequately controlled after surgery. [4, 5] In a study of 10,000 ambulatory surgery patients, patients who had orthopedic surgery had the highest incidence (16%) of postoperative pain. [4] It is especially this group of patients who are the greatest beneficiaries of peripheral nerve blocks. Many regional block techniques will in addition to surgical anesthesia provide an extended and superb postoperative analgesia. For example, customary doses of 0.5% bupivacaine or ropivacaine for ankle-foot block result in over 12 hours of complete analgesia after the surgery. Similarly, when 0.5-0.75% ropivacaine is used for popliteal block, analgesia up to 24 hours with minimal motor block is a norm. Another excellent example of how regional block techniques can be useful in the same-day surgery is anterior cruciate ligament reconstruction. This procedure is associated with severe postoperative pain frequently requiring hospital admissions. However, femoral or lumbar plexus block (with sciatic block when indicated) provide not only an excellent anesthesia but also superb analgesia facilitating timely discharge. [6]

With the ever increasing scope and complexity of the orthopedic procedures, the degree of postoperative pain is becoming a major limiting factor in ability to perform these surgeries in out-patients. However longer duration of analgesia can be achieved by using long acting local anesthetics or placing catheters in the vicinity of the nerves of interest. [7] With this method, the peripheral block is administered through a larger bore needle and a catheter, similar to those used in epidural anesthesia, is inserted and secured in place. The anesthetic can then be delivered either through an elastometric infusion pump or portable, battery powered infusion pumps with PCA capabilities at patients homes. Alternatively, peripheral nerve block catheters can be used to "top-up" with a long-acting local anesthetic before discharging patients homes.

By avoiding excessive use of narcotics in treatment of postoperative pain one can decrease the incidence of nausea, vomiting and unnecessary sedation before discharge home. However the full benefit of peripheral nerve block techniques depends not only on the skillful performance of the block and the right choice of the local anesthetic but also on patient management in the recovery room. The recovery room nurses, their education and institutional PACU discharge protocols seem to have an important, if not determining role over whether the advantages of regional anesthetic regimen can be transformed in an increased overall efficiency and earlier patient discharge. [8] In contrast to a common misconception that patients receiving peripheral nerve blocks must regain motor and sensory function before discharge homes, residual neuronal blockade is not only desirable by actually essential for effective postoperative analgesia and facilitation of early discharge. An active role of the anesthesiologist in the PACU, including the education of the PACU personnel, as well as a frequent communication with the PACU personnel is the best approach to capitalizing on many advantages of regional blocks.

The occasionally brought bias that the use of peripheral nerve blocks decreases the OR efficiency is neither true or substantiated by the available data. In fact, there is a considerable evidence that points to the contrary. Peripheral nerve blocks result in a rapid onset of anesthesia, predictable recovery and superb postoperative analgesia. These characteristics make them uniquely suited in outpatients without a negative impact on operating room efficiency. In fact, performing peripheral nerve blocks instead of neuraxial or general anesthesia is likely to increase the OR efficiency, since there is no time required for special patient positioning or hemodynamic interventions nor the "wake up" time such as after general anesthesia. However, postoperative nursing care remains an important factor in affecting the final discharge home. [9] This holds true even in patients who receive general anesthesia in addition to peripheral nerve blocks. [10] The turnover time can be even further reduced when the regional blocks are performed in the block rooms. While some labor intensive techniques may not gain acceptance because they require operating room time, many blocks can be placed in a well monitored preoperative holding area or a block room. This setup essentially obviates induction and emergence time and can greatly contribute to an efficiently run operating room.

The future for regional anesthesiologists in ambulatory surgery has never been brighter and more promising. The use of better equipment and an increasing insight into the functional regional anesthesia anatomy has resulted in a renaissance of the field. A number of more practical, accurate and efficacious new techniques have been introduced which have much simplified the cumbersome and complicated anatomical landmarks in the traditional approaches to major conduction blocks. [11, 12, 13, 14] More importantly, these new techniques are easier to master and teach and can be used even in patients in whom the classical approaches are not feasible. These techniques also likely to improve the acceptance of nerve blocks by the surgeons, patients and anesthesiologists.The introduction of continuous peripheral blocks has vastly increased the usefulness and flexibility of peripheral nerve blocks by extending analgesia for several days after the surgery. [15, 16] A wider implementation of these techniques may allow an increase in the scope and extent of orthopedic surgery in outpatients.

A significantly better equipment with improved insulated needles, catheters and nerve stimulators have become available. We have also seen the introduction of substantially less toxic and equally effective new local anesthetics, ropivacaine and levobupivacaine. The unique advantages of regional blocks can be further expanded by the concomitant use of various local anesthetic additives, such as a2 agonists. For instance, the use of clonidine with intermediate-acting local anesthetics is reported to result in a dose-dependent prolongation of anesthesia, analgesia and motor blockade. In the very near future regional anesthesia is likely to acquire ultra-long acting local anesthetic formulations lasting days to weeks following a single injection (liposomes and microspheres). This will clearly revolutionize the way we practice regional anesthesia. In addition to offering a controlled and prolonged delivery, these new formulations will be biodegradable, nonimunogenic and substantially less toxic.

After a relatively dormant period of several decades, there has been a recent explosion of new information, research and teaching in regional anesthesia. A few remarkable and innovative texts and interactive CD-ROM programs of remarkable educational value have been published. [17, 18, 19, 20] With an expansion of the Internet and global communication, the information is just a couple of clicks of keyboard and a few seconds away (Advances in Regional Anesthesia: www.AnesthesiaRegional.com). Recognizing the value of regional anesthesia techniques and the need for teaching of the various techniques, organized anesthesia societies, such as American Society of Anesthesiologists (ASA), American Society of Regional Anesthesia (ASRA) and the New York State Society of Anesthesiologists (NYSSA-PGA), host a number of regional anesthesia workshops at their yearly meetings. ASRA also organizes throughout the country a number of exceptionally highly rated regional one-day workshops in nerve blocks. A recent introduction of centers of excellence preceptorship programs by the generous support of pharmaceutical industry enabled those practitioners with some experience in regional anesthesia to significantly expand their abilities through a one-on-one intense two-day courses at the participating institutions (Astra-Zeneca Centers of Excellence Preceptorship Program).

A number of highly efficacious peripheral nerve block techniques can be used to provide excellent surgical anesthesia and good postoperative analgesia in patients undergoing lower extremity ambulatory surgery. It is almost universally accepted that these techniques offer numerous advantages in this setting and it is very likely that a shift away from central neuraxial blockade and general anesthesia toward peripheral nerve blocks will continue to take place in the near future. Judiciously and skillfully performed nerve blocks can facilitate fast-tracking (i.e., bypassing the postanesthesia care unit), allow early mobilization, decrease hospital stay, reduce unanticipated hospital admission, and reduce health care costs. With the rapidly expanding scope of ambulatory surgery, emergence of better block techniques and equipment, and imminently pending development of substantially more flexible local anesthetics, nerve blocks are rapidly becoming the anesthetic of choice for majority of patients undergoing ambulatory surgery.

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