A Surgeon's View: Dispelling Some Common PNB Myths

Keith Kenter, MD, Cincinnati

August, 2008

I'VE BEEN A HUGE FAN OF peripheral nerve blocks since the early 1990s, and today I offer a block to every one of my shoulder surgery patients. However, many of my colleagues in orthopedic surgery are not as enthusiastic. The reason, I think, is that they still subscribe to myths about PNBs that can prevent them from realizing their great advantages for patients and institutions alike. Here's a look at some of the most common myths and why they should no longer hold surgeons back.

Myth 1: PNBs prolong turnover time. PNBs do require some scheduling adjustments, but once you make them, PNBs actually reduce turnover time significantly. The key is to have the anesthesia team begin blocking the next patient outside the OR while the surgeon finishes the current case. That way, the patient is ready as soon as the surgeon is. Once this process is in place, cases with peripheral nerve blocks turn over quickly. Once the shoulder patient is in the OR, positioning is also much quicker. Since these patients don't need general anesthesia, we don't have to fuss with head control issues, and we don't need to intubate. And because the patient remains hemodynamically unaffected, we don't have to wait for emergence from general anesthesia after the procedure is over.

Myth 2: Lower extremity PNBs prevent safe ambulation. Skilled professionals can administer blocks that provide pain control while still allowing safe ambulation. It's important to distinguish between surgical pain control and post-op pain control. A short-acting anesthetic with a relatively high concentration during surgery can provide "solid" pain relief. After surgery, a longer acting anesthetic with a low concentration can continue pain relief while having less impact on motor function. Modern pumps can vary flow rates through continuous nerve-block catheters to provide even more flexibility.

Myth 3: Local anesthetic infusion is as effective as a PNB for pain control. It's true that some commercially sponsored studies comparing blocks with local infusion suggest that the two provide equivalent pain control. However, the independent studies indicate that PNBs are much more effective. For my patients, PNBs clearly provide better pain control. In my view, PNBs make a lot more theoretical sense because they stop the transmission of the pain signal and prevent the pain cascade from getting started, whereas a local infusion only ameliorates the response after the fact. Recent evidence also suggests that intra-articular infusions can cause chondrolysis in the shoulder.

Myths are powerful, persistent and persuasive, but we need to be guided by the truth. The truth about PNBs is that they prevent pain and PONV much more successfully than any other tool in our arsenal, and they're an invaluable component of a good multimodal pain control regimen. Discuss them with your anesthesia team and your patients.

Dr. Kenter is a sports medicine surgeon with the Division of Sports Medicine and Shoulder Reconstruction, Department of Orthopaedic Surgery, University of Cincinnati Medical Center.


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