Letter to the editor: Randomized double-blind trial of short- versus long-acting analgesia at the sacrospinous ligament
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We had the great pleasure to read the article titled “Randomized double-blind trial of short- versus long-acting analgesia at the sacrospinous ligament” written by Propst et al. .
The randomized double-blind trial attempted to evaluate and compare the potency of postoperative analgesia induced by liposome bupivacaine or lidocaine in patients undergoing in sacrospinous ligament fixation (SSLF). Over 8 months, 31 female patients with pelvic organ prolapse (POP) and undergoing SSLF were studied in those to two arms. The primary outcome was postoperative buttock-specific pain, of which the visual analog scale (VAS) scores were used as the pharmacodynamics index. Results reveled no differences between two arms in VAS scores assessing postoperative buttock-specific pain. The conclusions drawn were that there is no benefit between the use of long- and short-acting local anesthetics at the sacrospinous ligament in surgery for SSLF.
The assessment frequency of pharmacodynamics index has an important impact on result accuracy. Several studies in rats have shown that the mean duration of sensory nerve blockade induced by liposome bupivacaine was ~5 h [2, 3]. In rat experiments of liposome bupivacaine, the effectiveness of nerve block was measured at certain intervals that were less than one h in the first few hours [2, 3, 4].
There was one limitation in the methods used by Propst et al. . VAS scores were collected at the following time points: 1, 3, 6, 12, 24, 36, 48, 72, 96, and 120 h postoperatively. Time intervals of VAS scores collection postoperatively were not frequent enough for precise outcomes detection. Similarly, another clinical trial article researching the potency of liposomal bupivacaine in posterior colporrhaphy collected VAS at 4, 18, and 24 h postoperatively . The time intervals used when collecting experimental outcomes in pharmacodynamic research should be appropriately determined and based on the duration of efficacy to obtain accurate results.
Compliance with ethical standards
Conflicts of interest
- 1.Propst K, O'Sullivan DM, Steinberg AC. Randomized double-blind trial of short- versus long-acting analgesia at the sacrospinous ligament. Int Urogynecol J. 2018. https://doi.org/10.1007/s00192-018-3758-4.
- 4.McAlvin JB, Padera RF, Shankarappa SA, Reznor G, Kwon AH, Chiang HH, et al. Multivesicular liposomal bupivacaine at the sciatic nerve. Biomaterials. 2014;35(15):4557–64. https://doi.org/10.1016/j.biomaterials.2014.02.015.CrossRefGoogle Scholar