Comparison of 3 Techniques for Ultrasound-guided Femoral Nerve Catheter Insertion

Not Applicable

Completed

Brief Summary: This is a randomized study which will compare three femoral nerve catheter insertion techniques. Subjects will be randomized into one of thee groups, Group 1: ultrasound guided femoral nerve catheter using a stimulation needle and stimulating catheter, .Group 2: ultrasound guided femoral nerve catheter using a stimulation needle, but non-stimulating catheter, or Group 3: ultrasound guided femoral nerve block without stimulation.

Detailed Description: This is a randomized study which will compare three femoral nerve catheter insertion techniques. Subjects will be randomized into one of thee groups, Group 1: ultrasound guided femoral nerve catheter using a stimulation needle and stimulating catheter, .Group 2: ultrasound guided femoral nerve catheter using a stimulation needle, but non-stimulating catheter, or Group 3: ultrasound guided femoral nerve block without stimulation.

* Pain Scores after surgery with be measured using the VAS (Visual Analogue Scale). Subjects will be asked to rate their pain on a scale of 1-10.

* Block Performance time is the time from starting the block (after prepping and draping) until catheter is placed.

* Opioid requirements will be measured as the total amount of opioids (converted to morphine sulfate equivalents) used both during surgery, and during the first 48 hours after surgery.

* Block failure rate will be calculated as the rate of cases that requires repeating the block after surgery.

Recruitment & Eligibility

Inclusion Criteria

18 to 80 years old at time of surgery.
Male or female patients undergoing total knee replacement under either general or neuraxial anesthesia (spinal or epidural). Intraoperative, patients will receive spinal anesthetics with 15 mg bupivacaine and 25mcg of fentanyl intrathecally.

Exclusion Criteria

Primary Outcome Measures

Name	Time	Method
Time Weighted Average Verbal Response Scale Pain Score	48 hours after surgery	Time weighted average of verbal response scale (VRS) pain score on a scale from 0 (no pain) to 10 (worst pain imaginable). Verbal Response Scale (VRS) pain scores after surgery - which ranged from 0 (no pain) to 10 (maximum intolerable pain) - were assessed every 30 minutes in the recovery area and every 4 hours thereafter up to 48 hours postoperatively. These individual measurements were averaged for each patient using a time-weighted formula. (For a given patient, the observed VRS pain score profile as a function of time was linearly interpolated and integrated using the trapezoidal rule; then, the time-weighted average was calculated as the value of this integral divided by the total monitoring time of 48 hours.).
Opioid Consumption	48 hours after surgery	cumulative opioid consumption, where all opioids were converted to IV morphine equivalents

Secondary Outcome Measures

Name	Time	Method
Incremental Cost of Femoral Nerve Blocks	postoperative period when block is used	The incremental cost between strategies was calculated as the additional cost of one strategy to the next less costly strategy. There was no variance in the price because these prices were contracted with the hospital. The contracted price for a hospital does not change or fluctuate.
Block Performance Time	time elapsed from beginning the block to catheter placement	Block performance time, defined as the time from block start until catheter placement.