X-RAY VISION Ultrasound can significantly decrease continuous nerve block placement time and increase success

As we enter a new era of perioperative analgesia that focuses on improving patient recovery and satisfaction while decreasing opioid use, continuous peripheral nerve blocks (CPNBs) are becoming increasingly popular as part of a multimodal analgesia regimen. We're all pretty familiar with the reasons to consider CPNBs in the outpatient setting (see "Making the Case for Continuous Nerve Blocks" on page 40), but what about the keys to successfully administering them? This month we give our list of 8 tips for placing CPNBs. Though not exhaustive, taking this list into account will go a long way toward ensuring success while minimizing delays and complications.

1. Choose the right patient
This is perhaps the most important step to help avoid trouble with CPNBs. You are inserting a foreign device that can cause infection, nerve injury or local anesthetic toxicity. Patients must comprehend instructions and warnings from both a language and an educational standpoint. You should feel you can trust the patient to maintain insertion site integrity, change pump settings if appropriate and to alert you of concerns. The patient must also have realistic expectations in terms of placement, maintenance and analgesia.

2. Choose the right surgeon
You and the surgeon should be on the same page before proceeding with a CPNB, including understanding the time it will take to place the block, the degree and duration of analgesia expected, and common problems that may occur (for example, quadricep weakness with a femoral CPNB). A surgeon who expects pain scores of 0, or who doesn't know that Horner's syndrome from your interscalene block is common and inconsequential, may think poorly of your block — even if it was a complete success in your eyes. Ensure the catheter can be placed without delaying surgery. A dedicated block area is ideal. Also remember you must document that the surgeon actually "requested" the catheter in order to be paid for it. Establishing that he wanted the block can additionally prevent you from being thrown under the bus if complications occur, and help you when requesting more equipment or support.

INFECTION PREVENTION To prevent infections related to continuous nerve blocks, use a skin antiseptic and create a sterile field with towels or drapes.

3. Use the right equipment
A quality ultrasound machine can significantly decrease CPNB placement time and increase success. Your machine should afford easy visualization of anatomy for placement of your most common blocks. Make sure you can record ultrasound images of your blocks, associated with patient data and filed in the patient chart or stored electronically in case of a billing audit. Don't forget to choose appropriate probes. For example, a curvilinear probe is a wise investment if you do a lot of blocks that require deeper needle insertion, such as sciatics or infraclaviculars.

There are multiple needles designed to improve ultrasound visualization, so trial and choose wisely. Don't forget that the crux of CPNB is the infusion. Pick an infusion device that works best for your practice and patient population. Today's options vary in design, programmability, ease of use and price. Once you choose an infusion device, you must decide whether to fill them at your facility, or order them prefilled.

4. Choose your local anesthetic wisely
Choosing a local anesthetic involves both initial injection during placement and subsequent infusion via the catheter. The majority of anesthesiologists infuse 0.2% ropivacaine (Naropin) via the catheter at pre-determined rates +/- bolus settings. Ropivacaine has become commonplace in this setting due to a favorable safety profile and the propensity for analgesia with reduced motor involvement.

The choice of local anesthetic for initial injection is considerably more varied and largely depends on practice environment. Some staff at our institution use 2% lidocaine with epinephrine, which allows for rapid confirmation of a successful primary block and subsequent evaluation of analgesia with the catheter infusion alone. This approach can lessen overall catheter failures, but assumes you have the time, manpower, desire and expertise to replace suboptimal catheters. Using longer-acting local anesthetics such as 0.5% ropivicaine (Marcaine) limits evaluation of the catheter infusion before PACU discharge, but several of our staff recommend it in settings where catheter replacement is impractical. The emphasis here is on getting a good primary block for the first 16 to 24 hours (when analgesic requirements are the highest), and then hoping catheter placement is sufficient to maintain some degree of analgesia afterwards.

5. Know where your catheter rests
Considerable variability exists regarding CPNB placement techniques. Many use nerve stimulation while others prefer ultrasound, or even a combination of both. We can debate the efficacy of an individual style, but user familiarity ultimately determines a physician's success. Due to visual confirmation, patient comfort and a theoretical increase in safety, our preference is ultrasound. Ultrasound aids needle positioning, and affords continuous visualization during catheter placement and local anesthetic injection. When ultrasound is unavailable and we are using nerve stimulation, we always try to obtain stimulation with less than 0.5 milliamps. Remember not to overfeed catheters, especially if you can't visualize and are not stimulating them. It makes no sense to perfectly position a needle next to a nerve (either by nerve stimulation or ultrasound) and then blindly thread your catheter 3 to 5cm beyond it.

DRAWBACKS
Continuous Blocks Aren't for Everybody

Continuous nerve blocks are not without their drawbacks.

• The cost of equipment. It's an advantage to do blocks using ultrasound, but ultrasonographic equipment is a major purchase for a smaller surgery center. But as William F. Urmey, MD, associate attending anesthesiologist at the Ambulatory Surgery Center at the Hospital for Special Surgery in New York, N.Y., explains, "the advent of portable ultrasonographic guidance and catheters lets you place the needle or catheter optimally to ensure analgesia of a specific area."
• CPNBs take time to place. A single-shot block takes a minute, but placing a catheter takes time, says Jeffrey M. Richman, MD, director of regional anesthesia and acute pain at the University of Maryland St. Joseph's Medical Center in Towson, Md.
• CPNBs require an additional time commitment Not only do CPNBs take longer to place, but they require a 24/7 pain service to follow up with patients, answer any questions and address any issues.
• CPNBs are not recommended for every case. "Sometimes pain is an advantage in understanding what is happening to the patient," says Dr. Urmey. "In these cases you don't want a complete blockade; a partial blockade may be warranted." Also, if there is a chance for compartment syndrome, a block is not recommended. Additionally, septic patients are not candidates for regional anesthesia. CPNBs are not an option for patients with coagulopathy or abnormal bleeding, and in certain cases, with severe neuropathy.
• The patient must be able to care for himself. The patient must be able to care for himself. A CPNB should not be placed in a person who is mentally incapacitated. Ensure a caregiver will be present to help out with the care of the patient and the catheter. "If sending a patient home with a catheter, ensure the caregiver is capable of helping out, including removing the catheter when instructed," says Dr. Richman.

— Gail O. Guterl

6. Guard against infections, leaks and accidental pulls
Although rare, infections related to CPNBs can lead to serious consequences. We wear sterile gloves for all CPNBs, use a skin antiseptic and create a sterile field with towels or drapes. Place ultrasound probes in a sterile sleeve. Use sufficient gel and try to make a smooth, bubble-free interface between the sleeve and the probe so as not to diminish visualization. We suggest a tissue adhesive (Dermabond, for example) where the catheter exits the skin; it acts as a barrier against infection and leaks, and helps prevent catheter migration. Make sure you remove all blood, local anesthetic and ultrasound gel, and consider Mastisol Liquid Adhesive to ensure that the dressing stays firmly in place. We use a statlock device to hold the catheter in place, and then apply sterile Tegaderm transparent dressings. Remember to secure catheters away from the surgical or tourniquet field, or uncomfortable places for the patient. With proper attention and routine, leaks, infections and accidental pulls should be minimal.

7. See your patient in PACU
Visit patients in the PACU to assess catheter function and overall patient satisfaction, and to reiterate instructions. If a catheter is not working, troubleshoot and remedy the problem — by replacing the catheter, performing a rescue single shot, or simply removing the catheter and using other modes of analgesia. If the nerve block impedes normal motor activity (a femoral catheter, for example), make sure a sling or knee immobilizer is in place. Give the patient written instructions on block, infusion device and safety issues, and ensure he can contact someone at all times for concerns. Finish by reviewing other prescribed pain medications and how they should be taken. The goal is clear communication, patient safety and patient satisfaction.

CPNB PLACEMENT
Making the Case for Continuous Nerve Blocks

With a continuous nerve block, you can send a patient home and know he won't have pain for 2-3 days, getting him past the worst period for post-operative pain. "Regional anesthesia is the only way you can guarantee ongoing analgesia without the side effects of general anesthesia," says William F. Urmey, MD, associate attending anesthesiologist at the Ambulatory Surgery Center at the Hospital for Special Surgery in New York, N.Y. Other benefits include:

1. Patient satisfaction. Patient satisfaction is high for continuous blocks, says Jeffrey M. Richman, MD, director of regional anesthesia and acute pain at the University of Maryland St. Joseph's Medical Center in Towson, Md. Patients experience fewer side effects such as nausea and vomiting, sedation, constipation and pruritis, he says. Continuous nerve blocks are associated with minimal side effects and provide unlimited block duration at a distance from spinal and epidural areas so you don't have problems with the neuraxis, says Dr. Urmey. "If patients are taking anticoagulants, CPNBs let you avoid epidural hematomas. They have better sleep patterns post-operatively, less urinary retention and are up and about quicker and able to commence therapy."
   In his research, Dr. Richman has determined there is a 35 to 50% reduction in pain scores for patients with a CPNB as compared with those taking opioids.
   CPNB patients often receive a call from the anesthesiologist to check on their progress. "Anecdotally, I have seen this type of attention and care increase our reputation as a good place to go for surgery," says Dr. Richman.
2. Patient outcomes. With CPNBs, there's little or no pain with practically no side effects. When patients have less pain they tend to be up and about sooner, and the risk of DVT is lowered, says Dr. Urmey.
3. Cost savings. In a study reported in 2006, Dr. Richman estimated a $10.12 savings per patient because fewer interventions are required to treat intra-operative and post-operative side effects such as nausea and vomiting (Anesth Analg 2006;102:248-257).
4. OR team satisfaction. "I quickly discovered giving an injection and having a patient wake up pain-free was very satisfying to me as an anesthesiologist," says Dr. Richman. "That drove my interest in trying to expand on the types of blocks I could do." For Dr. Urmey, regional anesthesia is now almost second nature: "99% of surgeries I'm involved in are regional anesthesia."
5. Flexibility. With CPNBs, you can adjust the dosage, even stop it post-op to "ensure the nerves are OK and then restart it for pain control," says Dr. Urmey. "We have done that in certain circumstances to ensure a patient recovers motor function and for patients who might be especially anxious or are afraid of waking up with a numb limb." There are many types of blocks for all types of surgeries. "We do femoral, sciatic, axillary, interscalene, infraclavicular, supraclavicular, paravertebral and popliteal," says Dr. Richman.

— Gail O. Guterl

8. Keep good documentation to help troubleshoot
In the busy environment that most anesthesia providers work in, we can do multiple procedures back to back without much of a break. When you place a CPNB, however, you must absolutely track these patients. This can be as easy as storing patient data and contact info in a secure Excel file. Contact the patient daily until the catheter is removed, asking about the catheter site, pain score, current adjuncts and how much volume is left in the pump. All of this information will readily help troubleshoot issues that may arise. When the catheter is pulled, the tip of the catheter should be visualized and verified.