Continuous Blocks Hasten Discharge For TKA Patients

Potential benefits ‘enormous,’ but questions about safety remain

Author Michael Vlessides in  Anesthesia News Sept 8, 2010

 Toronto—Patients who undergo total knee arthroplasty and receive a four-day continuous femoral nerve block for pain achieve hospital discharge criteria 15 hours faster than those who receive only an overnight infusion of local anesthetic, according to a recent study.

The results, although not quite as promising as findings from a single-center study that preceded the new trial, suggest that the prolonged ambulatory blocks can get knee replacement patients out of the hospital faster.

“Compared with an overnight continuous femoral nerve block, does a four-day ambulatory continuous femoral nerve block shorten the time to discharge readiness? The answer is yes,” said Brian M. Ilfeld, MD, MS, associate professor of anesthesiology at the University of California, San Diego, who led the research.

Compelling Numbers

More than 1 million knee and hip arthroplasties are performed every year in the United States, and that number is expected to grow to 4 million annually within the next 20 years (J Bone Joint Surg Am 2007;89:780-785). Providing perineural infusions at home—following a single night in the hospital—to patients who undergo total knee arthroscopy (TKA) may improve their quality of life, reduce their risk for infection and reduce their risk for morbidity resulting from errors by health care providers, Dr. Ilfeld said.

The potential financial savings are enormous, too, Dr. Ilfeld added. More than 315,000 TKAs are performed annually in the United States, at a cost of more than $25,000 each and more than $7 billion overall. Between 50% and 70% of those outlays involve hospitalization and ancillary services.

“While the percentage of TKA procedures that ambulatory perineural infusion could be applied to is unknown, this technique constitutes a potentially significant fiscal advantage,” Dr. Ilfeld said. “In addition, decreasing hospitalization duration allows for an increased census and therefore increased operating room capacity.”

In an earlier study (Anesthesiology 2008;108:703-713), Dr. Ilfeld’s group found that the four-day ambulatory continuous femoral nerve block decreased the time to attain discharge criteria by 46 hours (25 vs. 71 hours, on average, respectively). However, he said, that trial involved an “artificial research environment” of a stand-alone clinical research center with one-to-one patient–nurse staffing ratio.

“The question is: Can we generalize from this single study to all patients?” Dr. Ilfeld said. “So we chose to redo this study at four public and private hospitals, hoping to have the results more generalizable to the general population.”

Dr. Ilfeld and colleagues enrolled 77 patients into the trial, each of whom received the preoperative continuous femoral nerve block, which was kept in place until the following morning. Patients were then randomized to either continue with perineural ropivacaine (n=39) or switch to saline (n=38).

The primary end point was the time patients needed to attain the following discharge criteria: adequate analgesia, independence from IV opioids and the ability to walk at least 30 meters. Patients were discharged with their continuous block and a portable infusion pump as early as the third day after surgery. Their catheters were removed on the fourth postoperative day.

Patients who received 0.2% perineural ropivacaine for four days reached all three discharge criteria in a median of 47 hours, compared with 62 hours for those who received ropivacaine alone until the morning following surgery (P=0.028), the researchers said.

Dr. Ilfeld, who reported his group’s findings at the 2010 Spring meeting of the American Society of Regional Anesthesia and Pain Medicine (abstract 2), said patients undergoing the four-day infusion met the discharge criterion for pain relief in 20 hours (range, 0-38 hours), compared with 38 hours (range, 15-64 hours) for controls (P=0.009). Independence from IV opioids was attained in 21 hours (range, 0-37 hours) for the treatment group and 33 hours (range, 11-50 hours) for controls (P=0.061). The 30-meter ambulation benchmark was reached in 40 (range, 25-68 hours) and 45 hours (range, 25-66 hours), respectively (P=0.780), a difference that was not statistically significant.

Falling Short?

Although Dr. Ilfeld described the results as clinically significant, he also noted some important caveats. “Continuous femoral nerve blocks induce quadriceps weakness,” he said. “And there were four falls in three patients in the four-day block group.” No falls were recorded among patients receiving normal saline.

Dr. Ilfeld said his group will soon be publishing data showing that continuous peripheral nerve blocks of the lower extremities increase the risk for falling after knee and hip arthroplasty (Anesthesia & Analgesia, in press).

Perhaps as important as the trial’s clinical findings was the realization that scientific investigations do not always mimic real life. “If you want to [apply] those results to your own center, it’s probably better to use the multicenter study results,” Dr. Ilfeld said. However, he stressed, “I do not now suggest, nor have I ever suggested that ambulatory infusion be used outside carefully controlled and [institutional review board]-overseen clinical trials until more details are available.”

André P. Boezaart, MD, PhD, professor of anesthesiology at the University of Florida, in Gainesville, said the risks associated with continuous femoral nerve blocks are not from the infusion itself, but rather the effects of the medication.

The falls are “assumed to be from weak quadriceps muscles, which is not an unavoidable side effect of the procedure,” Dr. Boezaart said.

“We do not know the optimal dose to provide sensory analgesia without affecting motor nerves, but our anecdotal experience with a 0.1% ropivacaine infusion at 1 to 3 mL per hour has been satisfactory,” added Andrea T. Esch, MD, also of the University of Florida, in Gainesville. “Although infection historically has a higher risk of occurring at a femoral site than other locations, it is not a legitimate enough concern to pursue earlier discontinuation or avoidance of this technique.”

Dr. Ilfeld’s poster was recognized as one of the three best presented at the meeting

CMS Changes Conditions of Participation (CoP) for Anesthesia Services Part 1 of 4

The Centers for Medicare and Medicaid Services (CMS) recently revised the Conditions of Participation (CoP) for anesthesia services which is outlined in Transmittal 59 dated May 21, 2010. This four (4) part blog post outlines the major compliance challenges associated with the new CoP and solutions to help hospitals assess vulnerabilities in anesthesia and sedation services.

The revised guidance added a significant amount of new language to the old guidelines. In summary, the revised language addresses the following four (4) areas:

  1. Types of Anesthesia Services: The revised guidance provides definitions of the various types of anesthesia related services (i.e. general anesthesia, regional anesthesia, monitored anesthesia, topical/local anesthesia, minimal sedation, moderate sedation) and indicates whether they involve the administration of “anesthesia”.
  2. Administration/Supervision Requirements: The revisions provide additional guidance regarding who may administer anesthesia and the supervision requirements of non-physician personnel, specifically Certified Registered Nurse Anesthetists (“CRNAs”).
  3. Pre and Post anesthesia evaluations: The revisions refine the interpretive guidelines by explaining the requirements for pre and post anesthesia evaluations.
  4. Intra-operative Reports: The guidance indicates the minimum elements required under the current standard of care for an anesthesia intra-operative report or record.

Part 1: Defining Anesthesia and Related Services

The new changes clearly define both anesthesia and sedation, borrowing from definitions found in the American Society of Anesthesiologists’ (ASA) most recent set of practice guidelines (Anesthesiology 2002; 96:1004-17), summarized here:

  • Anesthesia involves the administration of a medication to produce a blunting or loss of pain, voluntary and involuntary movement, autonomic function, and memory and/or consciousness.
  • Patients often require assistance in maintaining a patient airway, or correcting depressed spontaneous ventilation due to drug-induced depression of neuromuscular function.
  • Cardiovascular function may be impaired.
  • Anesthesia is used for those procedures when loss of consciousness is required for the safe and effective delivery of surgical services.

Monitored Anesthesia Care (MAC) includes the monitoring of the patient by a practitioner who is qualified to administer anesthesia. Deep sedation/analgesia is included in MAC.

  • In Deep Sedation/Analgesia, patients cannot be easily aroused but respond purposefully following repeated or painful stimulation.
  • The ability for the patient to independently maintain breathing function may be impaired.
  • Patients may require assistance maintaining an airway, spontaneous ventilation may be inadequate.
  • Cardiovascular function is usually maintained.
  • Deep sedation/analgesia includes the use of propofol.
  • Must be delivered or supervised by a practitioner as specified in 42 CFR 482.52(a).

Regional Anesthesia is the delivery of anesthetic medication at a specific level of the spinal cord and/or to peripheral nerves used when loss of consciousness is not desired, but sufficient analgesia and loss of voluntary and involuntary movement is required.

  • Regional anesthesia includes epidurals, spinals and other central neuraxial nerve blocks.
  • Given the potential for the conversion and extension of regional to general anesthesia in certain procedures, administration of regional and general anesthesia must be delivered or supervised by a practitioner as specified at 42 CFR 482.52(a).
  • Epidural or spinal route for the purpose of analgesia—during labor and delivery—is not considered anesthesia, and therefore it is not subject to the anesthesia supervision requirements.
  • If C-section is necessary, anesthesia supervision requirements would apply (42 CFR 482.52(a)).

In contrast, the new CoP also outline those services not subject to the anesthesia administration and supervision requirements (42 CFR 482.52(a)):

Topical or Local Anesthesia or Minimal Sedation in which:

  • Patients respond normally to verbal commands.
  • Although cognitive function and coordination may be impaired, ventilation and/or cardiovascular functions are unaffected.

Moderate Sedation/Analgesia (“Conscious Sedation”) in which:

  • Patients respond purposefully to verbal commands, either alone or accompanied by light tactile stimulation.
  • No interventions are required to maintain a patient airway.
  • Spontaneous ventilation is adequate.
  • Cardiovascular function is usually maintained.

Rescue Capacity

  • Hospitals are required to ensure that procedures are in place to rescue patients whose level of sedation becomes deeper than initially intended.
  • Intervention by a practitioner with expertise in airway management and advanced life support is required.
  • The qualified practitioner corrects the adverse physiologic consequences of the deeper-than-intended level of sedation and returns the patient to the originally intended level of sedation.

Tips for Compliance

To comply with this section of the regulations, changes in policies and practices may be necessary. Assuring that all areas have been addressed is the only way of avoiding violations on future surveys. Begin by assuring that the following items have been established in policy and practice:

  • Align the definitions for anesthesia and sedation with those supported by CMS and ASA.
  • Define where the different levels of anesthesia can occur and under what circumstances.
  • Evaluate the level of compliance with the requirements at each location where anesthesia and sedation is administered.