No Difference in Pain After Spine Surgery with Local Wound Filtration of Morphine and Ketorolac: A Randomized Controlled Trial

BackgroundControlling postoperative pain after spinal surgery is important for rehabilitation and patient satisfaction. Wound infiltration with local anesthetics may improve postoperative pain, but true multimodal approaches for achieving analgesia after spinal surgery remain unknown.Questions/purposesIn this randomized, controlled, double-blind trial after lumbar interbody fusion, we asked: (1) Does multimodal analgesia reduce VAS pain scores by a clinically important amount? (2) Does this analgesic approach reduce the amount of morphine patients consume after surgery? (3) Is this approach associated with fewer opioid-related side effects after surgery?MethodsThis study included 80 adult patients undergoing lumbar interbody fusion who were randomized into two groups: A control group (n = 40) who received infiltration of the surgical incision at the end of the procedure with an injection of 0.5% bupivacaine 100 mg (20 mL) and epinephrine 0.5 mg (0.5 mL), and the multimodal group (n = 40), who received wound infiltration with the same approach but with different medications: 0.5% bupivacaine 92.5 mg (18.5 mL), ketorolac 30 mg (1 mL), morphine 5 mg (0.5 mL), and epinephrine 0.5 mg (0.5 mL). There were no between-group differences in the proportion of patients who were male, nor in the mean age, height, weight, preoperative pain score, or surgical time. All treatments were administered by one surgeon. All patients, the surgeon, and the researchers were blinded to the allocation of patients to each group. Pain at rest was recorded using the VAS. Postoperative morphine consumption (administered using a patient-controlled analgesia pump) and opiod-associated side effects including nausea/vomiting, pruritus, urinary retention, and respiratory depression were assessed; this study was analyzed according to intention-to-treat principles. No loss to follow-up or protocol deviations were noted. We considered a 2-cm change on a 10-cm scale on the VAS as the minimum clinically important difference (MCID). Differences smaller than this were considered unlikely to be important.ResultsAt no point were there between-group differences in the VAS scores that exceeded the MCID, indicating no clinically important reductions in pain associated with administering multimodal injections. The highest treatment effect was observed at 3 hours that showed only a -1.3 cm mean difference between the multimodal and the control groups (3.2 ± 1.8 versus 4.5 ± 1.9 [95% CI -1.3 to -0.3]; p < 0.001), which was below the MCID. Morphine consumption was very slightly higher in the control group than in the multimodal group (2.8 ± 2.8 versus 0.3 ± 1.0, mean difference 2.47; p < 0.001). The percentage of patients reporting opioid-related side effects was lower in the multimodal group than in the control group. The proportions of nausea and vomiting were higher in the control group (30% [12 of 40] than in the multimodal group (3% [1 of 40]; p = 0.001). All of these side effects were transient and none was severe.ConclusionsMultimodal wound infiltration with an NSAID and morphine did not yield any clinically important reduction in pain or opioid consumption. Since no substantial benefit of adding these drugs to a patient’s aftercare regimen was achieved, and considering the potential risks of administering opioids and NSAIDs (such as, polypharmacy in older patients, serious adverse effects of NSAIDs), we recommend against routine use of this approach in clinical practice.Level of EvidenceLevel I, therapeutic study.     

Neomycin-loaded poly(styrene sulfonic acid-co-maleic acid) (PSSA-MA)/polyvinyl alcohol (PVA) ion exchange nanofibers for wound dressing materials

In this study, poly(styrene sulfonic acid-co-maleic acid) (PSSA-MA) blended with polyvinyl alcohol (PVA) was electrospun and then subjected to thermal crosslinking to produce PSSA-MA/PVA ion exchange nanofiber mats. The cationic drug neomycin (0.001, 0.01, and 0.1%, w/v) was loaded onto the cationic exchange fibers. The amount of neomycin loaded and released and the cytotoxicity of the fiber mats were analyzed. In vivo wound healing tests were also performed in Wistar rats. The results indicated that the diameters of the fibers were on the nanoscale (250 ± 21 nm). The ion exchange capacity (IEC) value and the percentage of water uptake were 2.19 ± 0.1 mequiv./g-dry fibers and 268 ± 15%, respectively. The loading capacity was increased upon increasing the neomycin concentration. An initial concentration of 0.1% (w/v) neomycin (F3) showed the highest loading capacity (65.7 mg/g-dry fibers). The neomycin-loaded nanofiber mats demonstrated satisfactory antibacterial activity against both Gram-positive and Gram-negative bacteria, and an in vivo wound healing test revealed that these mats performed better than gauze and blank nanofiber mats in decreasing acute wound size during the first week after tissue damage. In conclusion, the antibacterial neomycin-loaded PSSA-MA/PVA cationic exchange nanofiber mats have the potential for use as wound dressing materials.