Diclofenac for day-care arthroscopy surgery: comparison with a standard opioid therapy

Development of polycarbonate urethane-based materials with controlled diclofenac release for cartilage replacement

Hydrogels are very promising human cartilage replacement materials since they are able to mimic its structure and properties. Besides, they can be used as platforms for drug delivery to reduce inflammatory postsurgical reactions. Polycarbonate urethane (PCU) has been used in orthopedic applications due to its long-term biocompatibility and bio-durability. In this work, PCU-based hydrogels with the ability to release an anti-inflammatory (diclofenac) were developed, for the first time, for such purpose. The materials were reinforced with different amounts of cellulose acetate (CA, 10%, 15%, and 25% w/w) or carbon nanotubes (CNT, 1% and 2% w/w) in order to improve their mechanical properties. Samples were characterized in terms of compressive and tensile mechanical behavior. It was found that 15% CA and 2% CNT reinforcement led to the best mechanical properties. Thus, these materials were further characterized in terms of morphology, wettability, and friction coefficient (CoF). Contrarily to CNTs, the addition of CA significantly increased the material's porosity. Both materials became more hydrophilic, and the CoF slightly increased for PCU + 15%CA. The materials were loaded by soaking with diclofenac, and drug release experiments were conducted. PCU, PCU + 15%CA and PCU + 2%CNT presented similar release profiles, being able to ensure a controlled release of DFN for at least 4 days. Finally, in vitro cytotoxicity tests using human chondrocytes were also performed and confirmed a high biocompatibility for the three studied materials.

Pain relief after ambulatory surgery: Progress over the last decade

The concept of fast-track or ambulatory surgery appeared to facilitate early recovery and discharge from the hospital and early resumption of normal daily activities after elective surgical procedures as well to reduce the health-care costs. Multimodal/balanced analgesia is an increasingly popular approach for this. The use of conventional modalities including central neuraxial blockade and opioids cannot be extended to patients undergoing fast-track surgery. Hence, an aggressive perioperative analgesic regimen/protocol is required for effective pain relief, with minimal side effects and which could be managed easily by the patient or the relatives at home away from the hospital setting. Pharmacological therapy and regional anesthesia techniques have been utilized for postoperative pain management. The use of perineural, incisional, and intra-articular catheters and local anesthetic administration through elastomeric and electronic pumps is promising approach for effective pain management at home. The key to successful pain management of such procedures requires individually tailored education to patients or caregivers including information on treatment options for postoperative pain and use of multimodal analgesia. This review provides an overview of the current armamentarium of drugs and modalities available for effective management of patients undergoing day care surgeries and sheds light on newer modalities available.

The determination of histopathological and biochemical effects of the rabbit knee joint injected dexketoprofen trometamol

This study was conducted to investigate possible histopathological effects and biochemical reflections of intra-articular dexketoprofen trometamol. A total of 24 New Zealand rabbits were included in the study. Blood sampling was carried out from all animals on the first day, then they were randomly allocated either to the control group (Group C, n = 9) or the dexketoprofen trometamol group (Group D, n = 15). Group C underwent each two intra-articular injections of saline, 0.25 mL into right and 0.50 mL into left knee. Group D was injected 0.25 mL (6.25 mg) dexketoprofen trometamol into the right knee and 0.50 mL (12.5 mg) into the left. The groups were divided randomly into three. Tissue and blood samples were collected from Groups C1 and D1 on the first day, C2 and D2 on the second day and C3 and D3 on the 10th day of the study. Interleukin-1 (IL-1β), interleukin-6 (IL-6), tumour necrosis factor-alpha (TNF-α) and C-reactive protein (CRP) levels were studied. The histopathological examination of C and D groups did not present any deterioration. IL-6 basal levels were significantly higher in Group D2 compared with C2 and C3 compared with D3. Basal TNF-α levels were higher compared with day 1 in Group C1, and IL-6 and CRP levels were higher in Group D3. Also, none of the increases in these values are supported by histopathological evaluation results. Consequently, we suppose that dexketoprofen trometamol does not cause histopathological deterioration in articular cartilage of rabbits, and the increases in biochemical parameters exclusively are not clinically significant.

Parecoxib and indomethacin delay early fracture healing: a study in rats

Nonsteroidal antiinflammatory drugs (NSAIDs) are used to reduce inflammatory response and pain. These drugs have been reported to impair bone metabolism. Parecoxib, a specific COX-2 inhibitor, exerts an inhibitory effect on the mineralization of fracture callus after a tibial fracture in rats. Decreased bone mineral density (BMD) at a fracture site may indicate impairment of early healing, casting doubt on the safety of using COX-2 inhibitors during the early treatment of diaphyseal fractures. Forty-two female Wistar rats were randomly allocated to three groups. They were given parecoxib, indomethacin, or saline intraperitoneally for 7 days after being subjected to a closed tibial fracture stabilized with an intramedullary nail. Two and 3 weeks after surgery, the bone density at the fracture site was measured using dual energy xray absorptiometry (DEXA). Three weeks after the operation the rats were euthanized and the healing fractures were mechanically tested in three-point cantilever bending. Parecoxib decreased BMD at the fracture site for 3 weeks after fracture, indomethacin for 2 weeks. Both parecoxib and indomethacin reduced the ultimate bending moment and the bending stiffness of the healing fractures after 3 weeks. These results suggest COX inhibitors should be avoided in the early phase after fractures.

Negative effect of parecoxib on bone mineral during fracture healing in rats

BACKGROUND AND PURPOSE

Non-steroidal anti-inflammatory drugs (NSAIDs) are conventional cyclooxygen-ase (cox) inhibitors commonly used in musculoskeletal trauma to reduce the inflammatory response and pain, but they also seem to affect bone metabolism. Parecoxib is a cox inhibitor that selectively inhibits cox-2. Through their selective mechanism of action, these newer drugs are supposed to reduce the gastrointestinal side effects of conventional cox inhibitors. The effects on bone metabolism and healing have, however, not been fully elucidated. Thus, there are reasons for concern regarding the potential negative effects of these drugs on bone metabolism and bone repair. We investigated the effects of short-term administration of parecoxib on bone mineral formation and bone healing in rats.

ANIMALS AND METHODS

26 female Wistar rats were given parecoxib intraperitoneally for 7 days after a closed tibial fracture that was stabilized with an intra-medullary nail, and 26 animals were given saline. At 2, 3, and 6 weeks after surgery bone mineral density (BMD) at the fracture site was measured using dualenergy X-ray absorptiometry (DEXA). 6 weeks after the fracture, 14 rats from the parecoxib group and 16 rats from the placebo group were killed for mechanical testing, and the rest of the animals were killed for tissue analysis. The healing fractures and the intact contralateral tibias were mechanically tested by three-point cantilever bending.

RESULTS

The BMD at the fracture site was calculated as the average of the results after 2,3, and 6 weeks. Mean BMD was lower in the parecoxib group, 0.23 (SD 0.06) g/ cm2, than in the control group, 0.27 (SD 0.05) g/cm2 (p = 0.01). There were no statistically significant differences in mechanical properties of the healing fractures after 6 weeks. However, the study may have lacked sufficient statistical power to determine whether a negative effect on healing had occurred.

INTERPRETATION

No mechanical differences were detected between the control and treatment groups after 6 weeks, but they may have been present earlier in the fracture healing process. Our findings do, however, indicate that parecoxib given postoperatively for a week has a negative effect on mineralization during the early phase of fracture healing.

The changing role of non-opioid analgesic techniques in the management of postoperative pain

Given the expanding role of ambulatory surgery and the need to facilitate an earlier hospital discharge, improving postoperative pain control has become an increasingly important issue for all anesthesiologists. As a result of the shift from inpatient to outpatient surgery, the use of IV patient-controlled analgesia and continuous epidural infusions has steadily declined. To manage the pain associated with increasingly complex surgical procedures on an ambulatory or short-stay basis, anesthesiologists and surgeons should prescribe multimodal analgesic regimens that use non-opioid analgesics (e.g., local anesthetics, nonsteroidal antiinflammatory drugs, cyclooxygenase inhibitors, acetaminophen, ketamine, alpha 2-agonists) to supplement opioid analgesics. The opioid-sparing effects of these compounds may lead to reduced nausea, vomiting, constipation, urinary retention, respiratory depression and sedation. Therefore, use of non-opioid analgesic techniques can lead to an improved quality of recovery for surgical patients.

Comparison of the Efficacy and Safety of Intravenously Administered Dexketoprofen Trometamol and Ketoprofen in the Management of Pain after Orthopaedic Surgery

OBJECTIVE

This study aimed to evaluate the analgesic efficacy and tolerability of dexketoprofen trometamol, a nonsteroidal anti-inflammatory drug, in comparison with that of racemic ketoprofen (both administered by intravenous infusion), in patients with postoperative pain.

METHODS

This was a multicentre, randomised, double-blind, parallel-group study. 252 patients with moderate to severe pain following hip or knee replacement surgery performed under general anaesthesia were randomly assigned to receive either dexketoprofen trometamol 50 mg or ketoprofen 100 mg, both administered by intravenous infusion every 8 hours over 2 days. A level of > or =40 mm on a 100 mm visual analogue scale (VAS) for pain was required for inclusion in the study. Pain intensity on the VAS at different time-points after the administration of the first dose was assessed and the sum of pain intensity differences (SAPID(0-8 h)) was calculated as the primary efficacy variable. The use of rescue medication, maximum pain intensity difference (PID(max)), time to PID(max) and safety were also evaluated.

RESULTS

The mean (+/- SE) adjusted SAPID(0-8 h) scores in the per-protocol population were 310.9 +/- 19.2 and 326.3 +/- 19.0 mm x h after dexketoprofen trometamol and ketoprofen treatment, respectively. The 95% CI for the difference between treatments (-59.1 to 28.3) was fully included within the range of equivalence of +/-65.3 mm x h. There were no significant differences with regard to secondary variables. The need for rescue analgesia was high in both groups; 81.3% of patients receiving dexketoprofen trometamol treatment and 87.1% receiving ketoprofen treatment required rescue analgesia. The time to achieve PID(max) was 284.7 and 308.5 min after dexketoprofen and ketoprofen, respectively. Treatment- related adverse events were experienced by 16% of patients in the dexketoprofen trometamol group compared with 21.3% in the ketoprofen group. Most patients were concomitantly treated with low-molecular-weight heparin (94.4%), and no haemorrhagic events related to the surgical procedure were reported. No adverse events related to renal function were detected during the study.

CONCLUSION

The two medications were equivalent in terms of analgesic activity in the management of postoperative pain after orthopaedic surgery. The high use of rescue analgesics indicates a need for a multimodal approach to analgesia in this type of surgery. Dexketoprofen trometamol appeared to show a trend towards a better tolerability profile compared with the racemic compound.

Intra-articular Injection of Tenoxicam in Rats: Assessment of the Local Effects on the Articular Cartilage and Synovium

This study investigated the possible local adverse effects of intra-articular administration of tenoxicam in the rat knee joint. A total of 50 rats were given 0.25 ml of a standard preparation of tenoxicam by injection into the right knee joint and 0.25 ml of 0.9% saline solution by injection into the left knee joint as a control. Groups of 10 rats were killed 24 h, 48 h, 7 days, 14 days and 21 days after tenoxicam administration. Two rats were sham operated; one was killed on the first day and the other on the second day after this procedure. All the joints were prepared and sectioned for histological examination. Tissue loss and oedema were observed in the specimens obtained 24 h and 48 h after treatment with tenoxicam. No pathological changes were observed in the 7-day, 14-day and 21-day specimens, or in the control joints. Caution should be exercised when using intra-articular tenoxicam for postoperative analgesia.

Comparison between intra-articular bupivacaine with epinephrine and epinephrine alone on short-term and long-term pain after knee arthroscopic surgery under general anesthesia in day-surgery patients

BACKGROUND

: Postarthroscopy analgesia has been provided with intra-articular bupivacaine, but reported results are conflicting regarding efficacy and the duration of analgesia. The immediate and long-term effects of intra-articular bupivacaine with epinephrine after arthroscopic knee surgery were therefore studied in a day surgery setting.

METHODS

: 120 ASA I-II patients scheduled for arthroscopic knee surgery were given general anesthesia with spontaneous breathing via a laryngeal mask. In a randomized and blinded fashion half of them received, at the end of surgery, intra-articularly 20 mL 0.5% bupivacaine with epinephrine (B + E-group) and the other half 20 mL saline with epinephrine (S + E-group). All patients received ketoprofen 100 mg i.v. during surgery and another 100 mg 2-3 h postoperatively. The patients were observed for about 4.5 h in the day surgery unit before discharge.

RESULTS

: The results showed that in comparison with the S + E-group, significantly fewer patients in the B + E-group needed analgesics (P < 0.0001) and the amount required was also significantly less postoperatively, before discharge (about 4.5 h postoperatively) (P < 0.0001). The latency to the need for the first postoperative analgesic was shorter in the S + E-group patients (P < 0.0001). At home, during seven days after discharge, the need for analgesic (oral ketoprofen 100 mg) was greater in the B + E-group (P < 0.05), especially only during the second postoperative day, but the visual analoque pain scale (VAPS) scores were low with no differences between the groups. No complication occurred.

CONCLUSION

: It is concluded that a good postoperative pain control of intra-articular bupivacaine with epinephrine was found only in the immediate postoperative period (i.e. before discharge) in a day-surgery arthroscopic knee surgery patients.

Postoperative analgesia after arthroscopic knee surgery: a randomized, prospective, double-blind study of intravenous regional analgesia versus intra-articular analgesia

SUMMARY

The aim of this study was to determine the quality of postoperative analgesia in patients undergoing arthroscopic knee surgery using preoperative intravenous regional analgesia. After initial consultation with a statistician, we allocated 36 patients randomly and double-blind to 1 of 3 groups. Group A received intravenous regional analgesia preoperatively, group B received standard postperative intra-articular analgesia, and group C received saline and acted as the placebo. Our results showed no statistically significant difference in pain levels between the groups. However, there was a significantly larger amount of morphine administered by patient-controlled pumps in the placebo group when compared with the 2 treatment groups. There was no such difference between the 2 treatment groups. We concluded that preoperative regional analgesia in this setting is as good as but no better than intra-articular analgesia and that neither technique has any advantages over diclofenac plus patient-controlled analgesia.

Postoperative pain control in ambulatory surgery

Optimizing postoperative pain control is the key to further advancement in the field of ambulatory anesthesia. The current situation in postoperative pain management indicates room for improvement, especially in the area of patient education and the development of individualized discharge analgesic packages. Multimodal analgesia provides superior analgesia with a lower side-effect profile. Preoperative administration of analgesia would decrease the intraoperative analgesic requirement, which may lead to a smooth and rapid recovery. Finally, new, portable analgesic delivery systems are under investigation and may prove to be the method of choice for future postoperative pain, management in ambulatory anesthesia.

Low-dose intra-articular ketorolac for pain relief following arthroscopy of the knee joint

The systemic administration of nonsteroidal anti-inflammatory agents has been shown to improve analgesia following arthroscopy of the knee joint. Ketorolac 60 mg, when given intra-articularly, provides better postoperative analgesia than an identical dose administered systemically. We compared the postoperative analgesic effect of ketorolac 10 mg given intravenously with 5 mg intra-articularly in 60 patients undergoing arthroscopy of the knee joint under general anaesthesia. Patients were randomly allocated in a double-blind manner to receive 0.25% bupivacaine 20 ml and ketorolac 5 mg intra-articularly (n = 27) or intravenous ketorolac 10 mg followed by 0.25% bupivicaine 20 ml (n = 30) at the end of surgery. There were no differences between the groups in terms of their physical characteristics or in the nature of procedure performed. There was no statistical difference between the two groups in time to first analgesia or postoperative visual analogue pain scores at 1, 2 and 4 h (p = 0.6). The median consumption of a standard analgesic was reduced in the intra-articular group in the second 24-h period but this did not achieve statistical significance (p = 0.08). Only five patients in total needed postoperative morphine. A reduced amount of locally applied ketorolac (5 mg) provides similar analgesia to a higher systemic dose (10 mg) following knee arthroscopy.

Intra-articular tenoxicam relieves post-arthroscopy pain

BACKGROUND

Nonsteroidal anti-inflammatory drugs have been documented to be effective in the treatment of postoperative pain. The aim of this study was to evaluate the analgesic effect of local intra-articular injection of tenoxicam compared with intravenous injection on postoperative pain after arthroscopy.

METHODS

After day-case arthroscopy, 60 patients were randomized to receive either tenoxicam 20 mg in 20 ml of normal saline intra-articularly and 2 ml of normal saline i.v., or 20 ml of normal saline intra-articularly and 2 ml tenoxicam 20 mg i.v. Postoperative pain was assessed using a visual analogue scale and measuring analgesic requirements.

RESULTS

Pain scores were significantly lower in the intra-articular group at rest and during active flexion of the knee at 1, 2 and 4 hours postoperatively and during walking at 6 hours postoperatively (P < 0.05). Significantly more patients in the intravenous group required supplemental opioid analgesia within the first 4 hours postoperatively (P < 0.05).

CONCLUSION

Intra-articular tenoxicam 20 mg provided better analgesia and decreased the requirements for postoperative analgesic compared with i.v. tenoxicam 20 mg.

Preoperative application of piroxicam gel compared to a local anaesthetic field block for postoperative analgesia

The non-steroidal anti-inflammatory drugs inhibit prostaglandin synthesis and hence have an analgesic action. Following topical administration, the drug is concentrated in the tissues and so can have a local analgesic effect. This study investigated the effect of the preoperative application of topical piroxicam on postoperative analgesic requirement compared to a placebo group and a conventional local anaesthetic field block. Forty-two patients presenting for in-patient inguinal hernia repair were randomly allocated on a double-blind basis to have either piroxicam gel 15gm applied preoperatively, or an inguinal field block with 20 ml of 0.375% bupivacaine following induction of anaesthesia, or no treatment. Postoperative Visual Analogue Scores for pain on moving in group P, I or C on admission at 1h, 2h, and 4 h following surgery were: 2 vs 1 vs 6.5; 3 vs 3 vs 5; 3 v 2 vs 4.5; 3 vs 2 vs 5.0, respectively (P < 0.005). Median(range) time to first analgesia was 25.4(15-70) min in group I, 30.3(10-49) min in group P; this was not significantly different from group C21.5(7-70) min. Over the first 24 hours the postoperative morphine requirement was significantly less in the two treatment groups 30(20)mg in group I and 34(17) mg in group P and 71(15) in group C, P < 0.0001. There were no apparent NSAID-induced side-effects, or effects on wound healing. The preoperative administration of piroxicam (15gm) topically compared favourably with a preoperative local anaesthetic field block with respect to VAS scores, time to first analgesia and total morphine consumption. And both treatment groups provided significantly superior analgesia than the control group.

Patients' attitudes to rectal drug administration

One hundred adult patients attending for day case surgery were surveyed by anonymous questionnaire in order to determine their attitudes to rectal drug administration. Fifty four patients did not want an analgesic drug (diclofenac sodium) administered rectally whilst under anaesthesia, all preferring to take it orally if available. Ninety eight patients thought that drugs administered per rectum should always be discussed with them beforehand and a few had very strong feelings about this route of administration. We suggest that prescribers of rectal diclofenac should always discuss it with patients pre-operatively. Whilst many are happy to have suppositories, some young patients are sensitive about this and prefer to take such medication by mouth.

A comparison of diclofenac with ketorolac for pain relief after knee arthroscopy

We performed a double-blind controlled trial to compare the analgesic effect of two nonsteroidal anti-inflammatory drugs. We compared rectal diclofenac 100 mg given 1 h before induction of anaesthesia with intravenous ketorolac 10 mg given immediately before anaesthesia in 40 patients undergoing arthroscopy of the knee as day cases. A visual analogue scale was used to assess pain prior to discharge. Pain, analgesic consumption, sleep disturbance and restriction of activities were recorded by telephone enquiry 24 h after surgery. There was no difference in the pain parameters, sleep disturbance, or restriction of activity between groups. We suggest that ketorolac 10 mg intravenously and diclofenac 100 mg rectally provide comparable postoperative analgesia in the first 24 h after arthroscopy of the knee.

Analgesia following day-case knee arthroscopy--the effect of piroxicam with or without bupivacaine infiltration

Sixty patients presenting for day-case arthroscopy of the knee under general anaesthesia were studied. Patients were randomly allocated to receive, in addition to intramuscular piroxicam 20 mg, either bupivacaine 0.25% 20 ml applied locally to the knee at the end of the procedure (n = 30) or no further intra-operative analgesia (n = 30). Visual analogue pain scores were significantly lower at 1, 2 and 4 h postoperatively in the bupivacaine group (p < 0.05). A higher proportion of patients in the piroxicam-only group required supplemental analgesia before discharge from hospital. The combination of piroxicam and bupivacaine provided superior analgesia to piroxicam alone.

Diclofenac sodium versus fentanyl for analgesia in laparoscopic sterilization

The effectiveness of an anaesthetic technique employing diclofenac sodium as an analgesic given preoperatively by intramuscular injection was compared against one employing intravenous fentanyl in patients undergoing laparoscopic sterilization. Postoperative pain was marked and both drugs provided partial relief only. Patients in the diclofenac group had pain scores that were initially higher than those in the fentanyl group and the difference between the groups was statistically significant (P < 0.02). Patients in the diclofenac group who received postoperative supplemental morphine analgesia recorded lower pain scores at 30 min than comparable patients in the fentanyl group (P < 0.03). These findings suggest that neither drug provides sufficient analgesia for laparoscopic sterilization when given as a sole analgesic. Investigation of a combined analgesic technique employing morphine and a non-steroidal anti-inflammatory drug is warranted.

Indomethacin as adjunct analgesia following open cholecystectomy

Fifty patients scheduled for elective cholecystectomy were randomised to receive either indomethacin suppositories 200 mg p.r. at the end of anaesthesia, followed by 100 mg bd for three days, or placebo suppositories according to the same regimen. All patients were given intravenous pethidine via patient-controlled analgesia (PCA) postoperatively. The mean dose of pethidine required by the patients in the indomethacin group was significantly less than that used by the placebo group, the cumulative dose after three days being 530.7 mg (SD 664.0) and 1151.0 mg (682.0) for the indomethacin and placebo groups respectively. At the same time the patients in the indomethacin group had lower pain scores both at rest and with movement, though this was only statistically significant on the first day on movement. There was no statistical difference between the groups with respect to the incidence of nausea, indigestion, proctitis, volume of drainage from the wound drain, or width of bruising around the wounds. Serum creatinine levels were compared pre- and postoperatively where possible and showed no change in either group.

Diclofenac for pain relief after arthroscopy: a comparison of early and delayed treatment

The effect of diclofenac on pain after arthroscopy of the knee joint was investigated in 64 patients. The aim of this double-blind, placebo-controlled, randomised study was to compare administration before surgery with delayed treatment. The effect on postoperative pain was evaluated by means of a Visual Analogue Scale and recording of the need for additional analgesics postoperatively. After surgery, hourly assessments were performed within 6 h after the anaesthetic block (approximately 5 h after start of surgery), and on the morning after surgery. Both treatment with diclofenac before surgery and delayed treatment were superior to placebo concerning pain scores within 6 h after onset of anaesthesia (P < 0.0065 and P < 0.0005, respectively). On the morning after surgery, only delayed treatment was superior to placebo (P < 0.02). No differences in pain scores were evident between the different groups treated with diclofenac. No differences in the need for additional analgesics were found.

A comparison of diclofenac and ketorolac for postoperative analgesia following day-case arthroscopy of the knee joint

Seventy-one patients presenting for day-case arthroscopy were randomly allocated to receive either intramuscular diclofenac 75 mg or ketorolac 30 mg immediately after induction of anaesthesia. One hour after operation visual analogue pain scores were significantly lower in the ketorolac group compared with those receiving diclofenac. Pain scores at 2 and 4 h postoperatively were not significantly different between the two groups although six of those receiving diclofenac required opioid analgesia compared with only one in the ketorolac group. Discomfort in the operated knee was similar for both groups on the day following surgery, but pain from the intramuscular injection site was significantly greater in the diclofenac group. Intramuscular ketorolac 30 mg provided better postoperative analgesia and less pain at the injection site than diclofenac 75 mg.

Day case laparoscopy: a survey of postoperative pain and an assessment of the value of diclofenac

A randomised, controlled study was undertaken to assess the postoperative pain and side effects experienced by patients undergoing day case diagnostic laparoscopy and laparoscopic sterilisation, and to evaluate the effectiveness in these patients of peroperative diclofenac. Patients undergoing laparoscopic sterilisation had significantly higher pain scores at one hour postoperatively, and at discharge, than patients undergoing diagnostic laparoscopy (p less than 0.01) but there were no significant differences in pain scores 24 hours after discharge. The incidence of postoperative side effects following discharge from hospital was high, but there were no significant differences between the groups. Diclofenac had no significant effect in either group on the severity of postoperative pain, or the incidence of postoperative side effects.