Formal Project Prize Session
Single Shot Versus Continuous Saphenous Nerve Block for Postoperative Pain Management after Total Knee Replacement: A Randomised, Double-Blind Trial
Chin-Chin CHAN1, Vansie KWOK2
1 Department of Anaesthesiology and Operating Theatre Services, Queen Elizabeth Hospital, Hong Kong, 2 Associate Consultant, Department of Anaesthesiology and Perioperative Medicine, Hong Kong Children’s Hospital, Hong Kong
Background and Objectives: Saphenous nerve block (SNB) reduces pain following total knee replacement (TKR) but there is no consensus yet regarding the optimal mode of administration. The aim of this study was to compare the analgesic efficacy of single shot SNB and continuous SNB after TKR. We hypothesized that single shot SNB is comparable with continuous SNB in post-op pain score and opioid consumption (primary end point). Secondary end points were patient satisfaction, opioid-related side effects and catheter-related adverse events.
Methods: We performed a double-blind, randomised, controlled study of patients scheduled for unilateral TKR under spinal anaesthesia. The patients were randomised to receive either a single shot SNB (4 – 6ml 1% ropivacaine, followed by placebo injection) or continuous SNB (4 – 6ml of 1% ropivacaine, followed by intermittent boluses of ropivacaine at total 6 times per day) via a catheter. Post-op pain scores, daily and total fentanyl and tramadol consumption, patient satisfaction, opioid-related side effects and other adverse events were compared between the two groups.
Results: We enrolled 64 patients, of which 58 patients were analysed. Only the mean pain score during physiotherapy on post-op day 1 was significantly lower in the continuous SNB group at 4.34, compared with 5.45 in the single shot group (P = 0.044) using numeric rating scale. The difference did not continue into post-op day 2 (P = 0.952). There were also no differences regarding pain at rest, pain during active flexion, opioid consumption, or any of the secondary outcomes between the groups.
Conclusions: Continuous SNB provided better pain control only on post-op day 1 during physiotherapy as compared with single shot SNB. Pain scores at other measured time points and opioid consumption were comparable between the groups.