As a technique for administering regional anesthesia, dual guidance — the use of ultrasound imaging in conjunction with electrical stimulation to locate and target nerves — can help deliver safer, more successful peripheral nerve blocks, particularly among providers who are still developing their regional anesthesia skill sets. Here's a review of the advantages that dual guidance offers, what your facility will need to perform it and why it's possible your providers might even come to outgrow the method.

The case for dual guidance
Neither Medicare nor most third-party insurers reimburse surgical facilities for the addition of ultrasound to electrical nerve stimulation. CPT code 76942, Ultrasonic guidance for needle placement (e.g., biopsy, aspiration, injection, localization device), imaging supervision and interpretation, is not separately payable on Medicare's 2011 ancillary services list.

So why invest in the equipment and training necessary to implement dual guidance techniques in your regional anesthesia program? Because it will very likely pay you back in perioperative efficiency. As I've advised anesthesia providers and surgical administrators alike (see "Dual Guidance: Regional Anesthesia's Win-Win," Outpatient Surgery Magazine, July 2010, page 47, or at http://tinyurl.com/6xjy2a9), dual guidance offers anesthesia providers a few major advantages in placing peripheral nerve blocks.

• It confirms anatomy. Finding the nerve you want to anesthetize with electrical stimulation alone can prove challenging, since no 2 patients' anatomies are exactly alike. Ultrasound guidance eliminates the guesswork, confirming the location and identity of the nerve you're targeting and letting you place the local anesthetic as close as possible to it.
• It provides a backup. Motor response from nerve stimulation can be fickle. If you don't get the response you want, you have 2 options. You can either keep probing, cranking up the electrical current and the patient's anxiety; or inject the local anesthetic, secure in the knowledge that the ultrasound device has confirmed the location.
• It offers visualization. Ultrasound's real-time imaging shows not only the exact location of the nerves, but also the needle, its advancement toward and interaction with the nerve, and the spread of the injected anesthetic around the nerve, which verifies that the drug hasn't been delivered into the bloodstream and away from the site.

The upshot of this combination and the accuracy it offers is that local anesthesia takes action faster and more effectively. Greater nerve block success rates mean less of a need for general anesthesia and consequently faster recoveries and discharges. Plus, patients see less of a risk for temporary or permanent nerve damage and other complications of flawed anesthetic injections.

Some physicians have been hesitant about ordering regional anesthesia for fear that it will create delays in the surgical process. But dual guidance actually stands to improve the efficiency of just about any orthopedic procedure that requires the blocking of femoral, sciatic, axillary, interscalene or other nerves.

Preparing for the process
Dual guidance for regional anesthesia doesn't require a large amount of heavy equipment to accomplish, but there are a few purchases to budget for before you can get started: a peripheral nerve stimulator, an ultrasound imaging unit, needles and nerve block supplies, and perhaps optional accessories such as local anesthetic infusion pain pumps depending on your post-op pain management protocol.

If your anesthesia providers have been placing nerve blocks, you probably already have a peripheral nerve stimulator. If you don't have one, it can be obtained for about $1,000. It's a fairly simple piece of equipment; what it does is electrically "jump start" a nerve. There aren't too many challenging decision points to be made here, other than the model you choose should include a dial that lets you raise or lower the amount of current delivered — keeping in mind, of course, that there is no reliable, standard amount of milliamperage that guarantees a needle tip in close proximity to the nerve will always be effective, and always be non-injurious to the nerve.

Ultrasound imaging units can range from $28,000 to $35,000. There are several prominent manufacturers in this market. It may be advisable to have your anesthesia providers trial more than 1 product, with each of the devices in the facility simultaneously for a head-to-head trial.

My feeling is that the more compact, the more portable and the simpler the machine, the better. A small footprint doesn't take up much space when it's in use or in storage; portability lets you perform blocks in the OR, in a designated block room or in a pre-op bay; and too many knobs, bells and whistles can make it a needlessly complex device for the task. Consider investing in an ultrasound machine de-signed specially for administering blocks.

Of course, image quality is of paramount importance in your purchasing decision. I maintain that 90% of performing a block is identifying your target. If you cannot see the anatomy well, performing any block will be a struggle. In addition to high-quality images, your choice should also have the ability to store and print images.

At our facility, we focus on inexpensive needles that get the job done. In short, "getting the job done" means "we can see it on ultrasound." We've trialed echogenically enhanced ("reflective") needles, which are said to improve visibility, but we've found that with practice, we don't tend to need the extra enhancement. We don't use stimulating catheters, as we've found them to be expensive, time-consuming to place, and occasionally difficult to remove. What's more, in dual guidance using a stimulating needle and stimulating catheter would be redundant. The probes on the ultrasound that work well for us is the linear, 6mHz to 13mHz transducer. Curvilinear probes can add quite a bit of expense (possibly more than 60% of the cost of the entire machine), and we find that for our mostly adult patient population, the linear probe works fine.

As for the block itself, we keep it simple. We standardize the local anesthetic volume and concentration of our blocks and we look for the most cost effective way to do them. For our single-shot blocks, the overall cost of supplies for skin prep, nerve location and local anesthetic injection is under $30. If your post-op pain management regimen includes supplementing the nerve block with the continuous local anesthetic infusion of a pain pump for 2 to 3 days afterward, that will add a couple of hundred dollars in supplies.

Last but not least, your staff needs training and practice. There needs to be a commitment from your anesthesia providers to attend courses for hands-on training in ultrasound imaging techniques, and a commitment from your surgeons to be supportive of the learning curve. Visit other facilities to see how their anesthesia teams place blocks.

Hand-eye coordination is the ultimate aim of this training, though only through the repeated practice of scanning patients does a person get the sense of what to look for. At our facility, we've administered over 6,000 peripheral nerve blocks with ultrasound in the past 4 years. I've personally performed over 1,000 and I've probably watched another 1,500 being placed. What we've learned is, the more images you see, the more confident you become. So we often watch each other doing blocks, even if just for a couple of minutes. Every time you watch, you improve, even if you're not the one holding the probe.

Means to an end?
Perhaps the highest praise I can bestow on dual guidance for regional anesthesia is that it may improve your skills to the point that you eventually won't need both tools anymore to deliver a block. Given both nerve stimulation and ultrasound imaging, you'd think you had the best of both worlds, but in my opinion, the greatest value of the pairing is that eventually it makes the electro-location method obsolete.

The major advantage of dual guidance is that it lets anesthesia providers train their eyes to believe what they see. Until you have enough practice, you aren't convinced that what you think is a nerve is actually a nerve. It's like training wheels on a bike. There'll come a day when you have the skill and confidence to just jump on a two-wheeler and go.

Historically, I learned to do blocks with a nerve stimulator alone. Then I employed the dual technique. Now, I'd say 99% of the time I use ultrasound only, as do many of my colleagues here. The only time we tend to use a nerve stimulator is on the rare occasions when we're unable to visualize anatomical structures through ultrasound, such as with larger patients.

Medical literature has yet to make a convincing case that complications emerging from ultrasound location only, as opposed to location by nerve stimulation or dual guidance, are statistically different, and I personally believe that with time, ultrasound alone will prove to be the safer option. As for our results, we are fortunate to have an overall success rate of 98% for our patients.