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How to Make Continuous Infusions Work
10 tips from experienced practitioners.
Dianne Taylor
Publish Date: October 27, 2008   |  Tags:   Anesthesia

When continuous peripheral nerve block infusions work, they are as close to a panacea for post-op pain as you can get. Yet many anesthesiologists hesitate to send patients home with infusions in place, concerned over complications or patients managing their own care. Here's advice from experienced practitioners.

1. Screen patients
While peripheral nerve blocks work for almost all patients because their targeted effects are localized, exclude patients with hepatic or renal insufficiency as a way to avoid local anesthetic toxicity, says Brian M. Ilfeld, MD, MS, associate professor with the University of California San Diego Anesthesiology Department and Center for Pain Medicine. Also exclude those with heart or lung disease when the infusion may affect the phrenic nerve and ipsilateral diaphragm function (like interscalene or cervical paravertebral catheters), since this can cause ipsilateral diaphragm paralysis, says Dr. Ilfeld.

Screen for allergies to latex and the analgesic itself, says James P. Sullivan, DPM, a podiatric surgeon with the Jersey Shore University Medical Center in Neptune, N.J., and Ocean Medical Center in Brick, N.J. And don't send infusion pumps home with patients who, for any reason, can't comply with homecare instructions, he says.

2. Transition anesthesia carefully
Finetune the surgical anesthetic so it lasts only as long as the surgery itself. When the patient gets to the PACU, he should wake up without pain, but then the analgesia should begin to lighten so the patient regains some feeling, says Dr. Ilfeld. "We want a dramatic decrease in pain, but the patient still needs to have some feeling," he says. "We don't want complete numbness because if the patient can't feel a limb, he can't protect it." Dr. Ilfeld uses a more dilute anesthetic post-op and decreases the basal rate of the infusion while offering patient-controlled boluses for breakthrough pain. This, he says, prevents patients from trying to stand - and falling - in recovery and at home.

3. Secure the catheter
Catheter loosening and dislodgement is a common cause for concern. Even slightly loose catheters are more likely to leak, and leaking, in turn, further increases the risk of complete dislodgement, says Dr. Ilfeld. He uses several methods to reduce this risk, starting with hair removal, followed by subcutaneous tunneling of the catheter, application of a liquid adhesive under a medical dressing and the placement of a specially designed stabilization device like the Statlock. "Still, the rate of catheter dislodgement will also depend on the anatomic location," he says. "Blocks placed deep through the muscle come out less often than those closer to the surface." Popliteal catheters can also be hard to secure, since patients use crutches and there's a lot of movement around the knee. And the longer the catheter remains in, the higher the risk of dislodgement. Still, says Dr. Ilfeld, if you use these approaches and keep the catheter secure, your dislodgement rate should be less than 5 percent.

4. Consider extra padding
Orthopedic patients who receive continuous infusions may require extra padding and careful bandaging, especially around such bony prominences as the medial and lateral malleoli, and the anterior tibial crest, says Dr. Sullivan. Due to the analgesic's effectiveness, these patients may not know if a bandage is too tight; extra padding will help prevent ischemia.

5. Ensure bolus capability
Pick a pump that lets patients self-administer boluses of analgesic on top of the basal infusion. Each patient's pain threshold is different, and the same maintenance dose that works for one may not work for another, says anesthesiologist Robert Muscio, MD, medical director at the Center for Advanced Surgery & Pain Management in Neptune, N.J. Research shows that patients who can't self-bolus usually need larger doses of oral opiates for breakthrough pain. Since practitioners often tailor the maintenance dose to maximize infusion duration and reduce the motor block, breakthrough pain can be expected. A bolus dose helps patients get through physical therapy. "We typically bolus patients with 10 to 15cc of 0.25 percent bupivacaine before surgery, which lasts six to eight hours," says Dr. Muscio. "We maintain them on about 2cc per hour, with the ability to bolus every 15 minutes."

6. Tighten all connections
Before sending patients home, make sure all connections along the entire infusion system are tight - including the locks between the syringe and catheter, says Dr. Sullivan. "Sometimes leakage can come from the reservoir area, and it will slide down the catheter toward the bandage," he says. "This moistens the bandage and can loosen the catheter."

7. Educate patients and caregivers
Along with standard outpatient instructions, review block expectations, breakthrough pain treatment, instructions not to drive or operate machinery, catheter site care, bolus instructions, limb protection, weight-bearing considerations, what to do if the catheter leaks, signs and symptoms of possible catheter- and anesthetic-related complications, and the catheter removal plan.

Have a caretaker present during verbal instruction, as most patients have some post-op cognitive dysfunction. Manage expectations, says Dr. Muscio, so patients don't "think the catheter will resolve their pain 100 percent," which isn't always the case.

  • Do patients and their caretakers understand the challenges of going home with an insensate limb? Ensure they don't inadvertently bear weight.
  • Show patients how to use the bolus capability. If they overuse it and the analgesic overflows, the catheter may leak. Patients should also understand that there are safety measures built into the pumps to prevent overdose. When patients know this, they may feel less anxious.
  • Tell patients that the relief from the bolus will take a few minutes. Tell them to use adjunctive opioids if the pain remains unacceptable 15 minutes after the bolus dose, says Dr. Ilfeld.
  • Stress that heavy activity, restlessness or pulling on the site can cause leakage and catheter dislodgement. "They need to be as leery of the site as possible," says Dr. Sullivan.
  • Prepare patients to expect some leakage. Catheters come with numerous holes in their tips, and there's often a hole very near the skin, which causes some analgesic leakage. "It's not uncommon for catheters to wet the dressing a little, and this is the most common call I get from these patients," says Dr. Muscio. "Tell patients that this is normal. Show them the catheter holes." Distinguish between a slight clear leakage and bloody discharge. In the latter case, patients must contact the practitioner right away.
  • Teach patients and caregivers how to remove the catheter. Set up the catheter so the tapes and special locking devices overlap and peel off as one unit. This makes it relatively easy for patients to remove their own catheters. "If they don't overlap, it can be quite a chore to remove them," says Dr. Ilfeld.

8. Rx opioids for breakthrough pain
Since the continuous infusion won't provide complete pain relief, prescribe adjunctive opioids. This is easy to forget because the initial surgical block may be in effect during discharge, and patients often leave the facility pain-free. Once the block wears off, the patient's needs for adjunctive analgesic can rise depending on such factors as the type of surgery, other pain-relief methods like cryotherapy and the infusion regimen. In addition, patients will need back-up pain relief should the catheter turn out to be improperly placed or dislodged. "It's impossible to accurately predict which patients will require oral opioids," says Dr. Ilfeld, who gives all patients a prescription for oral analgesics and tells them to fill it immediately after leaving the facility.

9. Be available 24-7
Right now, different centers have different post-op support requirements. All facilities require a caretaker to drive the patient home and, at the minimum, facilities perform at least one follow-up phone call. Some also require the caretaker to stay with the patient overnight. Others require two calls a day, and some even provide a nursing visit. "If we're sending a patient home right after a total joint, for example, the patient will need a caretaker for the duration of the infusion," says Dr. Ilfeld. No matter what our practitioners all agree that you need to provide a telephone number to all patients and be available to take their calls 24-7.

10. Let patients remove their catheters
Research shows that 98 percent of patients are comfortable removing their own catheters. "When we first started, we asked patients to come in to the facility for catheter removal," says Dr. Sullivan. "We quickly realized this wasn't necessary. Almost all patients take out their own catheters now, and the less often they need to get in and out of the car, the happier they are."

Dr. Ilfeld also suggests having a nurse available to support patients over the telephone while they're removing their catheters.

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