SLR - January 2019 - Jeanny Rickards

Efficacy of Two Regional Pain Control Techniques in Pediatric Foot Surgery

Reference: Lloyd CH, Srinath AK, Muchow RD, Iwinski HJ Jr, Talwalkar VR, Walker JL, Montgomery C, Milbrandt T. Efficacy of Two Regional Pain Control Techniques in Pediatric Foot Surgery. J Pediatr Orthop. 2016 Oct-Nov;36(7):720–4.

Scientific Literature Review

Reviewed By: Jeanny Rickards, DPM
Residency Program: Drexel University College of Medicine/Hahnemann University, Philadelphia, PA

Podiatric Relevance: Understanding postoperative pain control in pediatric patients undergoing bony foot and ankle surgery, arthrodesis and osteotomies, with three different anesthetic techniques: 1) general anesthesia (GA), 2) GA + peripheral nerve block (PNB) with nerve stimulation (NS) or 3) GA + PNB with NS and ultrasound (US) guidance.

Methods: Retrospective chart review was performed from 2004 until 2012. One hundred three patients were stratified into three groups. GA was induced by mask using sevoflurane or intravenously with propofol. A single anesthesiologist performed all single-shot nerve blocks. Injected anesthetic was 0.25 percent bupivacaine or 0.2 percent ropivacaine, with 5 µg/mL epinephrine. Total volume did not exceed 3 mg/mL patient’s body weight. Visual analog scale (VAS) measured pain levels at two, four, six, eight, 12 and 24 hours postoperatively. Days of hospitalization, morphine and oxycodone use by weight and time to first PRN opioid use were recorded. All statistics were run in SPSS version 21. Post hoc tests were used when significant differences were found. One-way analysis of variance tested for length of stay (LOS), opioid use and time to first PRN analgesic. The percentage of pain-free (VAS 0) patients was calculated for each time point and analyzed using Z-test. All significance levels were set at P ≤ 0.05.

Results: Primary analysis showed no significant differences in pain scores between groups for postoperative hours two through 12. The US group had the highest proportion of patients pain-free for the first six hours, significantly greater than the GA group, but not statistically different to the NS group. Pain scores were highest for all groups at 24 hours, particularly for the US group with an average VAS score of 5.2±2.4, higher than both GA (3.4±2.6) and NS (3.5±2.5) groups at that time point. However, available data showed the US group dropped back to the level of the other two groups after this 24-hour spike. Regarding postoperative opioid use, both US and NS groups had significantly longer time to first PRN opioid use and used approximately 1/10th the amount of morphine. Average LOS was not significantly different.

Conclusion: Both US- and NS-PNB were associated with lower intravenous morphine use and a longer time to first PRN opioid dose, a clear benefit, as compared to GA. In adults, US-PNB has been shown to reduce the number of complications and to improve quality of regional blockade when compared with NS-PNB. Oberndorfer found in their randomized, blinded study that US-PNB lasted longer (508 vs. 335 min of NS-PNB) and required lower volumes of anesthetic to be successful. The 24-hour pain spike is consistent with bupivacaine and ropivacaine pharmacokinetics, indicating a strong rebound effect. Discussion of a possible solution to this effect includes the use of continuous PNB, longer-acting oral opioid taken before surgery or liposomal long-release bupivacaine, yet to be studied in children. Thus, as we continue to grow as a new generation of foot and ankle surgeons, it is important to understand the effect of anesthesia and its different techniques as part of our integral postoperative pain management in the pediatric population undergoing bony foot and ankle surgery.

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