ASA August 2003 Newsletter

Comfortably Numb (at Home): Trends in Regional Anesthesia and Pain Medicine

Terese T. Horlocker, M.D., President
American Society of Regional Anesthesia and Pain Medicine

“Just a little pin prick…
…but you may feel a little sick”

With these words in their 1979 classic “Comfortably Numb,” British rock group Pink Floyd unwittingly described the standard of postoperative pain management of the day: on-demand, opioid injection. Pain relief was delayed while the nurse responded to the patient’s request, obtained access to the opioid cabinet and finally administered the conservative dose of morphine or meperidine intramuscularly. Side effects were remedied in a similar fashion. The development of infusion pumps in the 1980s was followed by the introduction of patient-controlled (intravenous and neuraxial) analgesia, which revolutionized acute pain management.¹ Adverse events associated with epidural morphine infusions² resulted in a shift toward a local anesthetic-opioid combination in an attempt to minimize the disadvantages of each component.³ Currently, this regimen (along with nonopioid adjuvants) remains the standard for patients undergoing thoracic or abdominal surgery. Still, concern over neuraxial catheters in the presence of anticoagulation and the need for inpatient admission during catheterization have led to increased popularity of peripheral nerve blocks over the last decade.

The techniques of peripheral neural blockade were developed early in the history of anesthesia, but the improved safety and general anesthesia supplanted their use. For example, in their respective textbooks published in the first decades of the 20th century, Braun⁴ and Labat⁵ described intraoperative management of patients undergoing intra-abdominal, head and neck and extremity procedures using infiltration, peripheral, plexus and splanchnic blockade since neuraxial techniques were not widely applied at the time. The available local anesthetics, cocaine and procaine, essentially limited applications to intraoperative anesthesia. However, the introduction of long-acting local anesthetics as well as innovations in equipment technology, including the development of stimulating needles and catheters and portable pumps allowing local anesthetic infusion after hospital dismissal,⁶ have increased the success rate and popularity of continuous peripheral blockade.

Clinical studies consistently demonstrate improved perioperative outcomes in both inpatient and outpatient settings. Following major knee surgery, continuous femoral nerve block is associated with increased joint range of motion and earlier dismissal compared to conventional opioid analgesia and decreased catheter (technical) problems compared to continuous epidural block.^7,8 Likewise, indwelling brachial plexus catheters are often an integral component of rehabilitation following shoulder and elbow surgery.⁹ Placement of a peripheral catheter/
portable pump system may allow surgery previously considered “inpatient” to be performed on an outpatient basis.1¹⁰

Perhaps the most intriguing application of peripheral blockade is minimally invasive surgery (MIS), which encompasses new techniques, equipment innovations and advancements in adjuvant therapy. Patients undergoing MIS hip or knee replacement receive a combination sciatic-continuous lumbar plexus block for intraoperative anesthesia and postoperative analgesia. Breakthrough pain is managed solely with oral analgesics. Importantly, no intravenous opioids are administered. Patients are discharged home, sometimes on the operative day, with an indwelling psoas compartment catheter for 48 hours. Additional clinical studies are needed to define the safety and optimal applications of continuous peripheral techniques, particularly in patients dismissed with an indwelling catheter and ongoing local anesthetic infusion. In addition, the role of peripheral blockade in prevention and treatment of chronic pain syndromes remains largely unstudied.

Thus, peripheral nerve blocks represent a new era in regional anesthesia and analgesia. Competence in these techniques is crucial to future practice models. However, adequate training and proficiency affect utilization. A nationwide survey reported that while 98 percent of anesthesiologists perform peripheral techniques, most perform less than five per month (although most predict increased use in the future).¹¹ Likewise, despite improvements in needle/catheter technology and neural localization, these blocks often remain underutilized.

Studies evaluating proficiency in technical skills have noted that regional anesthetic procedures are significantly more difficult to learn than the basic manual skills necessary for a general anesthetic, such as intubation and arterial cannulation. While “minimum clinical experience” has been defined for several regional anesthetics, the minimum block numbers required for accreditation may be less than those needed to acquire competency in the technique.^{12, 13}

Finally, the majority of resident training programs do not provide formal training in peripheral blockade. Experienced clinicians and trainees both must have access to anatomic sections and simulators, allowing the proceduralist to explore the anatomical relationships between nerves and related structures prior to patient contact. Educational efforts by professional societies must increase to meet the clinical demand.

In conclusion, regional blockade has dramatically shifted over the last two decades from intermittent intramuscular opioid injection during an extended hospitalization to a continuous peripheral nerve block with a portable (and often disposable) pump delivering a local anesthetic solution in the home, supplemented by nonopioid analgesics. Given the current state of the art, one can only surmise our patients are “…comfortably numb.”

References:

1. Kwan JW. High-technology I.V. infusion devices. Am J Hosp Pharm. 1989; 46:320-335.

2. Stenseth R, Sellevold O, Breivik H. Epidural morphine for postoperative pain: Experience with 1085 patients. Acta Anaesthesiol Scand. 1985; 29:148-156.

3. Fischer RL, Lubenow TR, Liceaga A, et al. Comparison of continuous epidural infusion of fentanyl-bupivacaine and morphine-bupivacaine in management of postoperative pain. Anesth Analg. 1988; 67:559-563.

4. Braun H. Local Anesthesia: Its Scientific Basis and Practical Use, 3rd ed. Philadelphia: Lea & Febiger; 1914.

5. Labat G. Regional Anesthesia: Its Technic and Clinical Application. Philadelphia: W. B. Saunders; 1922.

6. Ilfeld BM, Morey TE, Enneking FK. Continuous infraclavicular brachial plexus block for postoperative pain control at home: A randomized, double-blinded, placebo-controlled study. Anesthesiology. 2002; 96:1297-1304.

7. Singelyn FJ, Deyaert M, Joris D, Pendeville E, Gouverneur JM. Effects of intravenous patient-controlled analgesia with morphine, continuous epidural analgesia and continuous three-in-one block on postoperative pain and knee rehabilitation after unilateral total knee arthroplasty. Anesth Analg. 1998; 87:88.

8. Capdevila X, Barthelet Y, Biboulet P, et al. Effects of perioperative analgesic technique on the surgical outcome and duration of rehabilitation after major knee surgery. Anesthesiology. 1999; 91:98.

9. O’Driscoll SW, Giori NJ. Continuous passive motion (CPM): Theory and principles of clinical application. J Rehabil Res Dev. 2000; 37:179-188.

10. Ilfeld BM, Morey TE, Wang RD, Enneking FK. Continuous popliteal sciatic nerve block for postoperative pain control at home: A randomized, double-blinded, placebo-controlled study. Anesthesiology. 2002; 97:959-965.

11. Hadzic A, Vloka JD, Kuroda MM, et al. The practice of peripheral nerve blocks in the United States: A national survey. Reg Anesth Pain Med. 1998; 23:241-246.

12. Konrad C, Schupfer G, Wietlisbach M, Gerber H. Learning manual skills in anesthesiology: Is there a recommended number of cases for anesthetic procedures? Anesth Analg. 1998; 86:635-639.

13. Kopacz DJ, Neal JM, Pollock JE. The regional anesthesia “learning curve.” What is the minimum number of epidural and spinal blocks to reach consistency? Reg Anesth. 1996; 21:182-190.

Terese T. Horlocker, M.D., is Professor of Anesthesiology, Mayo Clinic, Rochester, Minnesota.

return to top