ON TARGET One of the best ways to minimize CPNB-related risks is ultrasound, which provides real-time visualization and decreases insertion time and discomfort.

As more patients and providers experience the benefits of single-shot regional anesthesia in outpatient settings, many are wondering whether they can take the next step, asking, "Can we improve things further by using continuous peripheral nerve blockade?" The answer is a qualified yes. CPNB is being used more often in outpatient settings and the results have generally been positive. There are risks to consider, however, including infection, the potential for respiratory distress, local anesthetic systemic toxicity and falls.

What you can do to minimize risks
The keys to minimizing those risks boil down to careful patient and case selection, combined with clear and thorough communication. If you understand and mitigate the risk factors, you can achieve the benefits while minimizing the potential dangers.

• Upper extremity CPNB. This achieves and maintains potent analgesia and is widely used in the outpatient setting. It has several indications. For years, brachial plexus catheters have enabled patients having surgery on the shoulder, arm, forearm, wrist or hand to report lower pain scores and less nausea, and be discharged faster. Thanks to interscalene catheters, many shoulder surgeries that might previously have required hospital admissions have also been done as outpatient procedures. The same can be said of supra- and infraclavicular catheters, which have increased the number of hand and arm procedures carried out in outpatient settings.

The primary concern with upper extremity CPNB is respiratory complications. Supra- and infraclavicular blockades can cause pneumothoraces — air between the lung and chest — that aren't always immediately apparent. The risk of this complication may be increased when using a larger needle and with the increased manipulation necessary for catheter placement. Phrenic nerve blockade is another real and potentially very significant risk of interscalene and even supraclavicular blockade.

One of the best ways to minimize these risks is to use ultrasound, which not only gives real-time needle visualization and allows for more exact placement, it also lowers local anesthetic volumes, decreases insertion time and decreases discomfort. With or without ultrasound, be especially careful with continuous upper extremity blockade in patients with compromised cardiorespiratory function.

ADDED RISK Patients who have lower extremity CPNB are susceptible to falls and need to wear knee immobilizers at home.

• Lower extremity CPNB. Lower extremity CPNB is also increasing in popularity as anesthesia providers become more proficient with placement, and surgeons and patients become more familiar with the superior pain relief it provides. Femoral nerve catheters have helped convert anterior cruciate ligament surgery to the outpatient setting, and sciatic/ popliteal catheters have let ankle fracture and podiatric patients go home immediately after surgery.

PRACTICAL PEARLS
5 Tips for CPNB Success

Implementing outpatient CPNB can be daunting. However, under the right circumstances, the benefits (decreased pain, fewer opioid side effects, eliminated admissions, shortened discharge times, decreased costs and increased patient and surgeon satisfaction) outweigh the risks. These 5 tips may require a little extra time and/or expense, but they can help ensure success and prevent readmission, or worse:

1. Select patients who can be counted on to understand and take necessary precautions and to follow through on instructions.
2. Educate patients (and family or friends) and reiterate instructions both before and after surgery.
3. When possible, use ultrasound to facilitate placement.
4. Use liquid adhesive to prevent infections and catheter leaks.
5. To prevent falls and further injuries, make sure patients with lower extremity CPNB have knee immobilizers and patients with upper extremity CPNB have arm slings.

— Jerome M. Adams, MD, MPH, & Ryan D. Nagy, MD

But with the increasing use of lower extremity CPNB come additional risks — along with an increased risk of infection comes the very real risk of patient falls. The increased risk of infection is the result of catheter placement in less-visible, less-clean and less-dry areas. Those less-accessible placements make it more difficult for patients to watch and maintain their catheters. In fact, all of the clinically significant catheter infections we've seen at our institution have occurred with lower-extremity sites. We even saw a (non-infected) catheter patient who returned for a surgery follow-up exam 30 days after his surgery with his femoral catheter still in.

Naturally, patients are also more susceptible to falls if their lower extremity nerves are blocked and they can't feel their legs. That's one reason proper patient selection and education are of paramount importance with this group. Additionally, any patient who receives a femoral nerve block, especially a catheter, needs to wear a knee immobilizer at home.

Ideally, you'll educate patients first in a pre-op clinic, again just before surgery and again before discharge. Educate family members or friends who accompany the patient home. Both the patient and the family need to understand all instructions and all potential problems. Handouts that reiterate everything, list contact information and include FAQs are helpful. Don't forget to educate your surgeons about CPNBs, as they're frequently the first people patients contact when they have concerns.

When to avoid CPNB
If a patient is going home alone or has a language or other communication barrier, lower extremity CPNB is not a good option. As a case in point, a schizophrenic patient of ours received a sciatic catheter and a rescue femoral nerve block for an ankle fracture. He went home alone without a knee immobilizer and fell, fracturing his femur.

Also check for any predisposing comorbidities or risk factors. Ultimately, you need to feel confident that the patient is trustworthy and that there has been sufficient communication and education. Remember, for all outpatient CPNB, the patient becomes your surrogate eyes, ears and intervener/ protector. To prevent problems, communication after discharge is essential. We've found that daily phone conversations are sufficient for most patients. If you have any doubt, consider admitting the patient or using a different pain control method.