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Getting a “Knee Up” on Pain

Gone are the days when patients with knee replacements arrive on our unit postoperatively with multiple and often confusing orders for pain management.

Almost gone are the side effects — lethargy, confusion, nausea, vomiting, and pruritis that often accompany the use of narcotics. In the past, a PCA pump, plus IV and PO narcotics for breakthrough pain, was often routine to treat postop pain after total knee replacement. Not only could this approach affect length of stay in the hospital, but it could also color the patients’ perception of their care.

Although management of pain using narcotics is still available, there has been a concerted effort to lessen the use of systemic medications in favor of using our newly introduced femoral nerve block procedure.

The femoral nerve block involves a bolus of local anesthetic; ropivacaine is injected around the femoral nerve through an indwelling catheter, which is placed at the femoral nerve site at the time of surgery. A pain pump attached to the catheter continuously infuses ropivacaine to the area surrounding the femoral nerve. This protocol is being used throughout our unit, unless a patient is allergic to ropivacaine, which we have not seen yet.

Trial and error

Kathy Hughes, RN, and Dori Kerner, PT

Our journey to developing our current protocol began as most do — through trial and error. Our first attempt at local pain management solely involved the use of bolus injections of ropivacaine.

The first injection was performed in the recovery room by the anesthesiologist – the bolus of local anesthetic was injected through a catheter into the space around the femoral nerve in the femoral triangle. The bolus was effective for a time frame of approximately eight to 12 hours. If needed, the anesthesiologist could reinject the site through the indwelling catheter every 24 hours, for a total of three injections.

This local approach to pain management significantly decreased the patients’ perception of their pain at the surgical site and lessened the need for systemic narcotics for breakthrough pain.

Although the nerve block was usually highly effective, there were some variables that interfered with the success of this approach. For example, the duration of bolus effectiveness could be unpredictable, and the motor blockade at the knee could result in knee-buckling when the patient began walking postoperatively. In addition, patients often voiced a fear of falling, and staff had anxiety about safely mobilizing these patients because of the risk.

We knew that the local anesthetic aspect of pain management was on target, but perhaps the method of delivery needed to change. This is when ropivacaine pain pumps were introduced to the postop protocol for total knee replacements. Instead of receiving up to three separate bolus injections through the femoral catheter, the pain pump now delivers a continuous typical dose of 6 mL/hr of ropivacaine. In addition, the patient now has the ability to self-bolus a lesser amount (usually 2 mL) of the drug on demand.

Looking at outcomes

To evaluate the effectiveness of the changes from our first attempt at a new protocol to what we now use, we began tracking objective data — the use of supplemental systemic narcotics, existence of knee-buckling, and the average distance a patient ambulated on the first two postop days.

The baseline data was collected in the last quarter of 2006, before we began using the pain pumps. In January of 2007, we began our new protocol, using a continuous infusion of anesthetic, and started to collect comparison data.

We accomplished this with the cooperation of the staff from Anesthesiology, Recovery Room, Education, Physical and Occupational Therapy, and the Joint Replacement Center.

The results of our data collection included the following information —

• Before using the pain pump, 91% of patients had PCA pumps for on-demand narcotics. By the fourth quarter of 2007, only 9% of patients required narcotics through a PCA pump.

• When using boluses only, 41% of patients experienced knee-buckling. After the switch to a continuous indwelling catheter drip, only 26% experienced buckling.

• With boluses only, the average postop day-1 ambulation distance was three feet. After introducing the continuous drip, it was 23 feet.

• The average postop day-2 ambulation distance was 49 feet, with the bolus-only approach; after the change, it was 120 feet.

Our work continues

Throughout the past year, we have continued to tweak the protocol. When the ropivacaine pump and PO medications were not enough, we introduced one change -Toradol, an anti-inflammatory.

We usually give a loading dose of 30mg IV of Toradol, followed by 15mg IV push every six to eight hours for up to two days. We have had great success with this drug when we gave it with PO narcotics. Because pain is subjective, each patient’s needs are individualized.

Although placement of the catheter is performed with ultrasound guidance and the catheter tip is blunted so as not to enter the nerve but rather lay beside it, repositioning by the anesthesiologist may occasionally be required.

The results speak for themselves — our local pain management protocol has yielded positive patient outcomes in both patient comfort and ambulation, thus reducing the need for an extended length of hospital stay.

Editor’s Note: For more information on this procedure, contact the authors at Saint Francis Hospital, at (845) 431-8769.

By | 2020-04-15T15:24:17-04:00 June 2nd, 2008|Categories: New York/New Jersey Metro, Regional|0 Comments

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