The Future of Orthopedic Anesthesia

Here’s a look at 5 promising ways to tamp down the intense, persistent post-surgical pain of orthopedic surgery.

With CNBs, a percutaneous indwelling (or perineural) catheter provides a continuous local anesthetic. CNBs can relieve pain for days after surgery, as opposed to nerve blocks that provide analgesia for hours.

“People are realizing that single-shot blocks don’t do much good, especially if you’re trying to minimize opioid use,” says Gregory Hickman, MD, medical director and director of anesthesia at the Andrews Institute Ambulatory Surgery Center in Gulf Breeze, Fla. He places CNBs in cases ranging from rotator cuff and labrum repairs to total-knee replacements.

So what’s the sweet spot for CNB usage? “We leave the block in for 4 days, and patients discontinue the use of the catheter on day 4,” says Dr. Hickman. “We used to only do 3 days, but we noticed patients had some pain on that fourth day.”

Long-lasting pain relief. Opioid-sparing. Single-dose infiltration. What’s not to like about Exparel (liposomal bupivacaine)? Administered directly at the incision site during surgery, Exparel provides up to 72 hours of post-op pain relief, says Pacira Pharmaceuticals. Some say that number could be on the high side.

“We’ve done our own internal study and found that Exparel can last anywhere from 48 to 72 hours, but in most cases, it’s closer to 48,” says Dr. Hickman. “That means it wears off at an inopportune time for recovering patients.”

Plus, there’s the commitment aspect. “You’re essentially married to Exparel for the duration of usage, and you have to wait until it wears off,” says Nabil Elkassabany, MD, the director of orthopedic anesthesia at the Hospital of the University of Pennsyl-vania in Philadelphia. “If you do a femoral nerve block with a catheter, and you have a weak leg at 8 in the morning, all you have to do is stop the infusion for a few hours and the weakness will improve.”

Few challenge Exparel’s claim that it reduces the need for opioids. Studies have shown that patients went longer before needing opioids and required fewer opioids than those who didn’t receive Exparel.

With Medicare now reimbursing for Exparel in ambulatory surgical centers, many expect a surge in the drug’s usage. Exparel could soon face competition from other long-lasting local analgesics.

“Yes, Exparel is the only commercial drug out there right now, but there are a number of drugs in various stages of testing,” says Dr. Elkassabany. “I’m confident that in 5 or 10 years from now, you’ll have multiple drugs on the market.”

3. New uses for old drugs

Cryoanalgesia “will probably be common in 5 years,” says Brian M. Ilfeld, MD, MS, professor of anesthesiology in residence in the department of anesthesiology at the University of California San Diego.

Cryoanalgesia may be performed percutaneously by guiding a probe — with no hole at the end of it — next to a target nerve and then passing nitrous oxide through it until it hits the tip of that probe where the pressure drops and there’s dramatic cooling of the gas. The gas is then evacuated out through the probe, without getting injected or entering the patient’s tissue, but the ultimate effect is quite drastic. The tip of the probe freezes, creating an ice ball that encompasses the target nerve and subsequently freezes. Result: The nerve stops working and the patient gets pain relief ranging from 4 to 8 weeks, says Dr. Ilfeld.

For outpatient orthopedic procedures, the potential benefits of cryoanalgesia are significant, says Dr. Ilfeld, adding that it’s a safe and familiar procedure because it’s essentially the same as a peripheral nerve block. “Anesthesiologists who know how to do peripheral nerve blocks with ultrasound guidance already know how to do cryo,” says Dr. Ilfeld.

Another benefit of cryoanalgesia is the cost. After the initial purchase of the device, facilities will only need to pay for nitrous oxide and to resterilize reusable probes (although disposable probes are available).

What’s needed is more research into how cryo will be applied to common orthopedic procedures. “With procedures like shoulder arthroplasty and rotator cuff repair, we’d never do cryo on the entire brachial plexus, but we’d possibly treat the suprascapular nerve that innervates about two-thirds of the joint capsule,” says Dr. Ilfeld. “But these assumptions are all theoretical until we have quality randomized trials to draw from.”

The FDA cleared peripheral nerve stimulation decades ago for chronic pain, but it could prove useful in managing acute pain. You insert the lead of the nerve stimulator in a similar manner as a perinatal catheter using ultrasound guidance, but it delivers a small electric current to the nerve instead of a local anesthetic. Physicians only have to get the lead within 1 cm to 2 cm of the nerve, and it can remain in place for up to 60 days to outlast the pain of surgery. It’s also portable. Unlike continuous catheters that require patients to carry around a bulky infusion pump, stimulation devices are so small patients can stick them directly to their skin, leaving nothing to carry.

There are potential drawbacks. Peripheral nerve stimulation is significantly more expensive than cryo. Plus, there are questions about its potency. “According to the initial trials, nerve stimulation is nowhere near as potent as a long-lasting local anesthetic,” says Dr. Ilfeld.

But that’s not necessarily a deal-breaker. If you can use a local, anesthetic-based single-injection nerve block, and get the patient out of the PACU and home, then peripheral nerve stimulation becomes a very potent analgesic, says Dr. Ilfeld.

How potent? Early feasibility studies show very low opioid use and very low pain scores for procedures such as rotator cuff repairs, cases that are traditionally very painful after surgery. OSM