Association of peri-operative prescription of non-steroidal anti-inflammatory drugs with continued prescription of opioids after total knee arthroplasty: a retrospective claims-based cohort study.

Non-steroidal anti-inflammatory drugs (NSAIDs) are one of the mainstays of multimodal pain management. While effective for acute pain control, recent pre-clinical evidence has raised concerns regarding an association between NSAIDs and chronic pain and potential opioid use. Our objective was to explore the association between peri-operative use of prescription NSAIDs and the need for continued opioid prescriptions lasting 90-180 days in previously opioid-naïve patients undergoing total knee arthroplasty. A database of health claims in the USA was used to identify all opioid-naïve adult patients who underwent primary knee arthroplasty between January 2010 and October 2021. We evaluated the magnitude of association between peri-operative prescription NSAID claims and claims for opioids at 90 days postoperatively using multivariable logistic regression models. Secondary outcomes included: the magnitude of association between peri-operative NSAID prescription and claims for opioids at 180 days postoperatively; and identifying other potential factors associated with opioid claims at 90 days postoperatively. After risk adjustment using multivariable logistic regression models in the 789,736-patient cohort, the adjusted odds ratio (95%CI) for a continuous claim of opioids at 90 and 180 days postoperatively among patients with a peri-operative NSAID prescription within 30 days was 1.32 (1.30-1.35), p < 0.001; and 1.12 (1.10-1.15), p < 0.001, respectively. This estimate of effect remained robust at 90 days after accounting for known potential confounders, including pre-existing knee pain and acute postoperative pain severity. Similar analysis of other pain medications (e.g. paracetamol) did not detect such an association. This population-based cohort study suggests that peri-operative prescription NSAID use may be associated with continued opioid prescription claims at 90 and 180 days after knee arthroplasty, even after adjusting for other observed covariates for continuous opioid claims. These novel findings can inform clinical decision-making for post-surgical pain management, risk-benefit discussions with patients and future research.

Network meta-analysis of the analgesic effectiveness of regional anaesthesia techniques for anterior cruciate ligament reconstruction.

Anterior cruciate ligament reconstruction can cause moderate to severe acute postoperative pain. Despite advances in our understanding of knee innervation, consensus regarding the most effective regional anaesthesia techniques for this surgical population is lacking. This network meta-analysis compared effectiveness of regional anaesthesia techniques used to provide analgesia for anterior cruciate ligament reconstruction. Randomised trials examining regional anaesthesia techniques for analgesia following anterior cruciate ligament reconstruction were sought. The primary outcome was opioid consumption during the first 24 h postoperatively. Secondary outcomes were: rest pain at 0, 6, 12 and 24 h; area under the curve of pain over 24 h; and opioid-related adverse effects and functional recovery. Network meta-analysis was conducted using a frequentist approach. A total of 57 trials (4069 patients) investigating femoral nerve block, sciatic nerve block, adductor canal block, local anaesthetic infiltration, graft-donor site infiltration and systemic analgesia alone (control) were included. For opioid consumption, all regional anaesthesia techniques were superior to systemic analgesia alone, but differences between regional techniques were not significant. Single-injection femoral nerve block combined with sciatic nerve block had the highest p value probability for reducing postoperative opioid consumption and area under the curve for pain severity over 24 h (78% and 90%, respectively). Continuous femoral nerve block had the highest probability (87%) of reducing opioid-related adverse effects, while local infiltration analgesia had the highest probability (88%) of optimising functional recovery. In contrast, systemic analgesia, local infiltration analgesia and adductor canal block were each poor performers across all analgesic outcomes. Regional anaesthesia techniques that target both the femoral and sciatic nerve distributions, namely a combination of single-injection nerve blocks, provide the most consistent analgesic benefits for anterior cruciate ligament reconstruction compared with all other techniques but will most likely impair postoperative function. Importantly, adductor canal block, local infiltration analgesia and systemic analgesia alone each perform poorly for acute pain management following anterior cruciate ligament reconstruction.

Analgesic benefits of the quadratus lumborum block in total hip arthroplasty: a systematic review and meta-analysis.

The quadratus lumborum block (QLB) is reported to reduce pain and improve function following total hip arthroplasty; however, randomised controlled trials evaluating the benefits of adding this block to general or spinal anaesthesia in this population are conflicting. We performed a systematic review seeking randomised controlled trials investigating QLB benefits for total hip arthroplasty, stratifying comparisons regarding the addition of QLB to either general or spinal anaesthesia. The primary outcome was 24-h area under the curve (AUC) pain score. Pain scores were interpreted in the context of a population-specific minimal clinically important difference of 1.86 cm on a 10-cm visual analogue scale, or an AUC pain score of 5.58 cm.h. Secondary outcomes included analgesic consumption, functional recovery and opioid-related side-effects. In all, 18 trials (1318 patients) were included. Adding QLB to general or spinal anaesthesia improved 24-h AUC rest pain scores by a mean difference (95%CI) of -3.56 cm.h (-6.70 to -0.42; p = 0.034) and - 4.19 cm.h (-7.20 to -1.18; p = 0.014), respectively. These improvements failed to reach the pre-determined minimal clinically important difference, as did the reduction in analgesic consumption. Quadratus lumborum block improved functional recovery for general, but not spinal, anaesthesia. Opioid-related side-effects were reduced with QLB regardless of anaesthetic modality. Low-to-moderate quality evidence suggests that the extent to which adding QLB to either general or spinal anaesthesia reduces postoperative pain and opioid consumption after total hip arthroplasty is statistically significant but may be clinically unimportant for most patients. However, adding QLB to general anaesthesia might enhance functional recovery. Taken together, our findings do not support the routine use of QLB as part of multimodal analgesic regimens for total hip arthroplasty.

Quality of recovery scores in deep serratus anterior plane block vs. sham block in ambulatory breast cancer surgery: a randomised controlled trial.

Deep serratus anterior plane block has been widely adopted as an analgesic adjunct for patients undergoing breast surgery, but robust supporting evidence of efficacy is lacking. We randomly allocated 40 patients undergoing simple or partial mastectomy with sentinel node biopsy to receive either a pre-operative deep serratus anterior plane block (serratus group) or a placebo injection (sham group), in addition to systemic analgesia. The primary outcome measure was the quality of recovery score at discharge, as assessed by the quality of recovery-15 questionnaire at various time-points. Secondary analgesic outcomes included: pain severity; postoperative opioid consumption; opioid-related side-effects; patient satisfaction up to 7 days postoperatively; and persistent postoperative pain up to 3 months after surgery. All patients who were recruited completed the study. There were no differences in the quality of recovery-15 scores between patients in the serratus and control groups, with mean (SD) scores of 96 (14) and 102 (20) for the control and serratus groups, respectively. We were also unable to detect differences in any of the secondary analgesic outcomes examined. The addition of a deep serratus anterior plane block to systemic analgesia does not enhance quality of recovery in patients undergoing ambulatory breast cancer surgery.

Intra-articular infiltration analgesia for arthroscopic shoulder surgery: a systematic review and meta-analysis.

Phrenic-sparing analgesic techniques for shoulder surgery are desirable. Intra-articular infiltration analgesia is one promising phrenic-sparing modality, but its role remains unclear because of conflicting evidence of analgesic efficacy and theoretical concerns regarding chondrotoxicity. This systematic review and meta-analysis evaluated the benefits and risks of intra-articular infiltration in arthroscopic shoulder surgery compared with systemic analgesia or interscalene brachial plexus block. We sought randomised controlled trials comparing intra-articular infiltration with interscalene brachial plexus block or systemic analgesia (control). Cumulative 24-h postoperative oral morphine equivalent consumption was designated as the primary outcome. Secondary outcomes included visual analogue scale pain scores during the first 24 h postoperatively; time-to-first analgesic request; patient satisfaction; opioid-related side-effects; block-related adverse events; and any indicators of chondrotoxicity. Fifteen trials (863 patients) were included. Compared with control, intra-articular infiltration reduced 24-h postoperative analgesic consumption by a weighted mean difference (95%CI) of -30.9 ([-38.9 to -22.9]; p < 0.001). Intra-articular infiltration also reduced the weighted mean difference (95%CI) pain scores up to 12 h postoperatively, with the greatest reduction at 4 h (-2.2 cm [(-4.4 to -0.04]); p < 0.05). Compared with interscalene brachial plexus block, there was no difference in opioid consumption, but patients receiving interscalene brachial plexus block had better pain scores at 2, 4 and 24 h postoperatively. There was no difference in opioid- or block-related adverse events, and none of the trials reported chondrotoxic effects. Compared with systemic analgesia, intra-articular infiltration provides superior pain control, reduces opioid consumption and enhances patient satisfaction, but it may be inferior to interscalene brachial plexus block patients having arthroscopic shoulder surgery.

Perineural and intravenous dexamethasone and dexmedetomidine: network meta-analysis of adjunctive effects on supraclavicular brachial plexus block.

Both perineural and intravenous dexamethasone and dexmedetomidine are used as local anaesthetic adjuncts to enhance peripheral nerve block characteristics. However, the effects of dexamethasone and dexmedetomidine based on their administration routes have not been directly compared, and the relative extent to which each adjunct prolongs sensory blockade remains unclear. This network meta-analysis sought to compare and rank the effects of perineural and intravenous dexamethasone and dexmedetomidine as supraclavicular block adjuncts. We sought randomised trials investigating the effects of adding perineural and intravenous dexamethasone or dexmedetomidine to long-acting local anaesthetics on supraclavicular block characteristics, including time to block onset and durations of sensory, motor and analgesic blockade. Data were compared and ranked according to relative effectiveness for each outcome. Our primary outcome was sensory block duration, with a 2-h difference considered clinically important. We performed a frequentist analysis, using the GRADE framework to appraise evidence. One-hundred trials (5728 patients) were included. Expressed as mean (95%CI), the control group (local anaesthetic alone) had a duration of sensory block of 401 (366-435) min, motor block duration of 369 (330-408) min and analgesic duration of 435 (386-483) min. Compared with control, sensory block was prolonged most by intravenous dexamethasone [mean difference (95%CI) 477 (160-795) min], followed by perineural dexamethasone [411 (343-480) min] and perineural dexmedetomidine [284 (235-333) min]. Motor block was prolonged most by perineural dexamethasone [mean difference (95%CI) 294 (236-352) min], followed by intravenous dexamethasone [289 (129-448)min] and perineural dexmedetomidine [258 (212-304)min]. Analgesic duration was prolonged most by perineural dexamethasone [mean difference (95%CI) 518 (448-589) min], followed by intravenous dexamethasone [478 (277-679) min] and perineural dexmedetomidine [318 (266-371) min]. Intravenous dexmedetomidine did not prolong sensory, motor or analgesic block durations. No major network inconsistencies were found. The quality of evidence for intravenous dexamethasone, perineural dexamethasone and perineural dexmedetomidine for prolongation of supraclavicular sensory block duration was 'low', 'very low' and 'low', respectively. Regardless of route, dexamethasone as an adjunct prolonged the durations of sensory and analgesic blockade to a greater extent than dexmedetomidine. Differences in block characteristics between perineural and intravenous dexamethasone were not clinically important. Intravenous dexmedetomidine did not affect block characteristics.

Peri-articular infiltration analgesia for shoulder surgery: a systematic review and meta-analysis.

Effective analgesic alternatives to interscalene brachial plexus block are sought for shoulder surgery. Peri-articular infiltration analgesia is a novel, less invasive technique, but evidence surrounding its use is unclear. This systematic review and meta-analysis aims to evaluate the utility of peri-articular infiltration analgesia in shoulder surgery. We searched literature for trials comparing peri-articular infiltration analgesia with control or with interscalene brachial plexus block. Control groups received no intervention, placebo or systemic opioids. The primary outcome was cumulative oral morphine equivalent consumption during the first 24 h postoperatively. Secondary outcomes included: rest pain scores up to 48 h; risk of side-effects; and durations of post-anaesthetic care unit and hospital stay. Data were pooled with random-effects modelling. Seven trials (383 patients) were included. Compared with control, peri-articular infiltration analgesia reduced 24-h oral morphine consumption by a mean difference (95%CI) of -38.0 mg (-65.5 to -10.5; p = 0.007). It also improved pain scores up to 6 h, 36 h and 48 h, with the greatest improvement observed at 0 h (-2.4 (-2.7 to -1.6); p < 0.001). Peri-articular infiltration analgesia decreased postoperative nausea and vomiting by an odds ratio (95%CI) of 0.3 (0.1-0.7; p = 0.006). In contrast, peri-articular infiltration analgesia was not different from interscalene brachial plexus block for analgesic consumption, pain scores or side-effects. This review provides moderate evidence supporting peri-articular infiltration for postoperative analgesia following shoulder surgery. The absence of difference between peri-articular infiltration analgesia and interscalene brachial plexus block for analgesic outcomes suggests that these interventions are comparable, but further trials are needed to support this conclusion and identify the optimal peri-articular infiltration technique.

Should continuous rather than single-injection interscalene block be routinely offered for major shoulder surgery? A meta-analysis of the analgesic and side-effects profiles.

BACKGROUND: Major shoulder surgery is associated with moderate-to-severe pain, but consensus on the optimal analgesic approach is lacking. Continuous catheter-based interscalene block (CISB) prolongs the analgesic benefits of its single-injection counterpart (SISB), but concerns over CISB complications and difficulties in interpreting comparative evidence examining major and minor shoulder procedures simultaneously, despite their differences in postoperative pain, have limited CISB popularity. This meta-analysis evaluates the CISB analgesic role and complications compared with SISB for major shoulder surgery. METHODS: We retrieved randomised controlled trials (RCTs) comparing the effects of CISB to SISB on analgesic outcomes and side-effects after major shoulder surgery. Postoperative opioid consumption at 24 h was designated as the primary outcome. Secondary outcomes included 24-48 h opioid consumption, postoperative rest and dynamic pain scores up to 72 h, time-to-first analgesic, recovery room and hospital stay durations, patient satisfaction, postoperative nausea and vomiting, respiratory function, and block-related complications. RESULTS: Data from 15 RCTs were pooled using random-effects modelling. Compared with SISB, CISB reduced 24- and 48-h oral morphine consumption by a weighted mean difference [95% confidence interval] of 50.9 mg [-81.6, -20.2], (P=0.001) and 44.7 mg [-80.9, -8.7], (P<0.0001), respectively. Additionally, CISB provided superior rest and dynamic pain control beyond 48 h, prolonged time-to-first analgesic, enhanced satisfaction, and reduced postoperative nausea and vomiting without complications. CISB caused an 11.0-11.7% decrease in respiratory indices. Result heterogeneity was successfully explained. CONCLUSIONS: High-level evidence indicates that CISB provides superior analgesia up to 48 h after major shoulder surgery, without increasing side-effects, compared with SISB. The importance of CISB-related changes in respiratory indices is questionable.

Evidence basis for using perineural dexmedetomidine to enhance the quality of brachial plexus nerve blocks: a systematic review and meta-analysis of randomized controlled trials.

BACKGROUND: Dexmedetomidine has been proposed as a perineural local anaesthetic (LA) adjunct to prolong peripheral nerve block duration; however, results from our previous meta-analysis in the setting of brachial plexus block (BPB) did not support its use. Many additional randomized trials have since been published. We thus conducted an updated meta-analysis. METHODS: Randomized trials investigating the addition of dexmedetomidine to LA compared with LA alone (Control) in BPB for upper extremity surgery were sought. Sensory and motor block duration, onset times, duration of analgesia, analgesic consumption, pain severity, patient satisfaction, and dexmedetomidine-related side-effects were analysed using random-effects modeling. We used ratio-of-means (lower confidence interval [point estimate]) for continuous outcomes. RESULTS: We identified 32 trials (2007 patients), and found that dexmedetomidine prolonged sensory block (at least 57%, P < 0.0001), motor block (at least 58%, P < 0.0001), and analgesia (at least 63%, P < 0.0001) duration. Dexmedetomidine expedited onset for both sensory (at least 40%, P < 0.0001) and motor (at least 39%, P < 0.0001) blocks. Dexmedetomidine also reduced postoperative oral morphine consumption by 10.2mg [-15.3, -5.2] (P < 0.0001), improved pain control, and enhanced satisfaction. In contrast, dexmedetomidine increased odds of bradycardia (3.3 [0.8, 13.5](P = 0.0002)), and hypotension (5.4 [2.7, 11.0] (P < 0.0001)). A 50-60µg dexmedetomidine dose maximized sensory block duration while minimizing haemodynamic side-effects. No patients experienced any neurologic sequelae. Evidence quality for sensory block was high according to the GRADE system. CONCLUSIONS: New evidence now indicates that perineural dexmedetomidine improves BPB onset, quality, and analgesia. However, these benefits should be weighed against increased risks of motor block prolongation and transient bradycardia and hypotension.

Reduced hemidiaphragmatic paresis with extrafascial compared with conventional intrafascial tip placement for continuous interscalene brachial plexus block: a randomized, controlled, double-blind trial.

BACKGROUND.: The incidence of hemidiaphragmatic paresis with continuous interscalene brachial plexus block (CISB) can approach 100%. We tested the hypothesis that extrafascial placement of the catheter tip reduces the rate of hemidiaphragmatic paresis compared with intrafascial tip placement for CISB while providing effective analgesia. METHODS.: Seventy patients undergoing elective major shoulder surgery under general anaesthesia were randomized to receive an ultrasound-guided CISB plexus block for analgesia with the catheter tip placed either within (intrafascial group) or immediately outside (extrafascial group) the brachial plexus sheath midway between the levels of C5 and C6. Catheters were bolus dosed with ropivacaine 0.5% 20 ml before surgery, followed by an infusion of ropivacaine 0.2% at 4 ml h -1 for the first 2 days after surgery. The primary outcome was hemidiaphragmatic paresis measured by M-mode ultrasonography on postoperative day (POD) 1. Secondary outcomes included forced vital capacity, forced expiratory volume in 1 s, and rest pain scores. RESULTS.: The incidence of hemidiaphragmatic paresis on POD 1 was significantly reduced in the extrafascial group {intrafascial, 41% [95% confidence interval (CI) 25-59%]; extrafascial, 15% (95% CI 5-32%); P =0.01}. We were unable to detect a difference between groups in any of the functional respiratory outcomes or in rest pain scores [numerical rating scale (1-10): intrafascial, 3 (95% CI 2-3); extrafascial, 3 (95% CI: 2-4); P =0.93] on POD 1. CONCLUSIONS.: Placement of the catheter tip immediately outside of the brachial plexus sheath reduced the incidence of hemidiaphragmatic paresis on POD 1 associated with ultrasound-guided CISB while providing effective analgesia after major shoulder surgery. Our results do not support the routine placement of the catheter tip within the brachial plexus sheath for CISB. CLINICAL TRIAL REGISTRATION.: NCT02433561.

Extrafascial injection for interscalene brachial plexus block reduces respiratory complications compared with a conventional intrafascial injection: a randomized, controlled, double-blind trial.

BACKGROUND: Hemidiaphragmatic paresis after ultrasound-guided interscalene brachial plexus block is reported to occur in up to 100% of patients. We tested the hypothesis that an injection lateral to the brachial plexus sheath reduces the incidence of hemidiaphragmatic paresis compared with a conventional intrafascial injection, while providing similar analgesia. METHODS: Forty ASA I-III patients undergoing elective shoulder and clavicle surgery under general anaesthesia were randomized to receive an ultrasound-guided interscalene brachial plexus block for analgesia, using 20 ml bupivacaine 0.5% with epinephrine 1:200 000 injected either between C5 and C6 within the interscalene groove (conventional intrafascial injection), or 4 mm lateral to the brachial plexus sheath (extrafascial injection). The primary outcome was incidence of hemidiaphragmatic paresis (diaphragmatic excursion reduction >75%), measured by M-mode ultrasonography, before and 30 min after the procedure. Secondary outcomes were forced vital capacity, forced expiratory volume in 1 s, and peak expiratory flow. Additional outcomes included time to first opioid request and pain scores at 24 h postoperatively (numeric rating scale, 0-10). RESULTS: The incidences of hemidiaphragmatic paresis were 90% (95% CI: 68-99%) and 21% (95% CI: 6-46%) in the conventional and extrafascial injection groups, respectively (P<0.0001). Other respiratory outcomes were significantly better preserved in the extrafascial injection group. The mean time to first opioid request was similar between groups (conventional: 802 min [95% CI: 620-984 min]; extrafascial: 973 min [95% CI: 791-1155 min]; P=0.19) as were pain scores at 24 h postoperatively (conventional: 1.6 [95% CI: 0.9-2.2]; extrafascial: 1.6 [95% CI: 0.8-2.4]; P=0.97). CONCLUSIONS: Ultrasound-guided interscalene brachial plexus block with an extrafascial injection reduces the incidence of hemidiaphragmatic paresis and impact on respiratory function while providing similar analgesia, when compared with a conventional injection. CLINICAL TRIAL REGISTRATION: NCT02074397.

Facilitatory effects of perineural dexmedetomidine on neuraxial and peripheral nerve block: a systematic review and meta-analysis.

UNLABELLED: Nerve blocks improve postoperative analgesia, but their benefits may be short-lived. This quantitative review examines whether perineural dexmedetomidine as a local anaesthetic (LA) adjuvant for neuraxial and peripheral nerve blocks can prolong the duration of analgesia compared with LA alone. All randomized controlled trials (RCTs) comparing the effect of dexmedetomidine as an LA adjuvant to LA alone on neuraxial and peripheral nerve blocks were reviewed. Sensory block duration, motor block duration, block onset times, analgesic consumption, time to first analgesic request, and side-effects were analysed. RESULTS: were combined using random-effects modelling. A total of 516 patients were analysed from nine RCTs. Five trials investigated dexmedetomidine as part of spinal anaesthesia and four as part of a brachial plexus (BP) block. Sensory block duration was prolonged by 150 min [95% confidence interval (CI): 96, 205, P<0.00001] with intrathecal dexmedetomidine. Perineural dexmedetomidine used in BP block may prolong the mean duration of sensory block by 284 min (95% CI: 1, 566, P=0.05), but this difference did not reach statistical significance. Motor block duration and time to first analgesic request were prolonged for both intrathecal and BP block. Dexmedetomidine produced reversible bradycardia in 7% of BP block patients, but no effect on the incidence of hypotension. No patients experienced respiratory depression. Dexmedetomidine is a potential LA adjuvant that can exhibit a facilitatory effect when administered intrathecally as part of spinal anaesthesia or peripherally as part of a BP block. However, there are presently insufficient safety data to support perineural dexmedetomidine use in the clinical setting.

Duration of analgesic effectiveness after the posterior and lateral transversus abdominis plane block techniques for transverse lower abdominal incisions: a meta-analysis.

BACKGROUND: Both posterior and lateral transversus abdominis plane (TAP) block techniques provide effective early (0-12 h) postoperative analgesia after transverse incision surgery. However, whether either technique produces prolonged analgesia lasting beyond 12 h remains controversial. This meta-analysis examines the duration of analgesia associated with posterior and lateral TAP blocks in the first 48 h after lower abdominal transverse incision surgery. METHODS: We retrieved randomized controlled trials (RCTs) investigating the analgesic effects of TAP block compared with control in patients undergoing lower abdominal transverse incision surgery. Outcomes sought included interval postoperative i.v. morphine consumption and also rest and dynamic pain scores at 12, 24, 36, and 48 h postoperatively. Opioid-related side-effects and patient satisfaction at 24 and 48 h were also assessed. The 12-24 h interval morphine consumption was designated as a primary outcome. RESULTS: Twelve RCTs including 641 patients were analysed. Four trials examined the posterior technique and eight assessed the lateral technique. Compared with control, the posterior TAP block reduced postoperative morphine consumption during the 12-24 h and 24-48 h intervals by 9.1 mg (95% CI: -16.83, -1.45; P=0.02) and 5 mg (95% CI: -9.54, -0.52; P=0.03), respectively. It also reduced rest pain scores at 24, 36, and 48 h, and also dynamic pain scores at 12, 24, 36, and 48 h. Differences were not significant with the lateral TAP block. CONCLUSION: Based on the comparisons with control, the posterior TAP block appears to produce more prolonged analgesia than the lateral TAP block. Future RCTs comparing these two techniques are required to confirm our findings.

Peri-operative intravenous administration of magnesium sulphate and postoperative pain: a meta-analysis.

Intravenous magnesium has been reported to improve postoperative pain; however, the evidence is inconsistent. The objective of this quantitative systematic review is to evaluate whether or not the peri-operative administration of intravenous magnesium can reduce postoperative pain. Twenty-five trials comparing magnesium with placebo were identified. Independent of the mode of administration (bolus or continuous infusion), peri-operative magnesium reduced cumulative intravenous morphine consumption by 24.4% (mean difference: 7.6 mg, 95% CI -9.5 to -5.8 mg; p < 0.00001) at 24 h postoperatively. Numeric pain scores at rest and on movement at 24 h postoperatively were reduced by 4.2 (95% CI -6.3 to -2.1; p < 0.0001) and 9.2 (95% CI -16.1 to -2.3; p = 0.009) out of 100, respectively. We conclude that peri-operative intravenous magnesium reduces opioid consumption, and to a lesser extent, pain scores, in the first 24 h postoperatively, without any reported serious adverse effects.

The analgesic efficacy and safety of neuraxial magnesium sulphate: a quantitative review.

Eighteen published trials have examined the use of neuraxial magnesium as a peri-operative adjunctive analgesic since 2002, with encouraging results. However, concurrent animal studies have reported clinical and histological evidence of neurological complications with similar weight-adjusted doses. The objectives of this quantitative systematic review were to assess both the analgesic efficacy and the safety of neuraxial magnesium. Eighteen trials comparing magnesium with placebo were identified. The time to first analgesic request increased by 11.1% after intrathecal magnesium administration (mean difference: 39.6 min; 95% CI 16.3-63.0 min; p = 0.0009), and by 72.2% after epidural administration (mean difference: 109.5 min; 95% CI 19.6-199.3 min; p = 0.02) with doses of between 50 and 100 mg. Four trials monitored for neurological complications: of the 140 patients included, only a 4-day persistent headache was recorded. Despite promising peri-operative analgesic effect, the risk of neurological complications resulting from neuraxial magnesium has not yet been adequately defined.

In-depth characterization of polyolefin plastomers/elastomers (ethylene/1-octene copolymers) through hyphenated chromatographic techniques.

The chemical composition distribution (CCD) of three single site made ethylene/1-octene copolymers was investigated through offline-hyphenation of solvent gradient interaction chromatography (SGIC) with 1H NMR. Thus, a clear, non-linear correlation between SGIC elution time and chemical composition was found under the specific measurement conditions applied here. The application of 1H NMR as detection allowed to determine the CCD with unprecedented accuracy. 2D-LC of the copolymers revealed the correlation between CCD and molar mass distribution (MMD) in a quantitative manner. Furthermore, this approach allowed a comparison between the response behavior of an evaporative light scattering detector (ELSD, semi-quantitative, commonly applied in SGIC) and that of an infrared (IR) detector (quantitative, commonly applied in SEC). As a result, it could be shown that ELSD results are close to IR results for the system investigated here, in other words, the often-criticized semi-quantitative response behavior of the ELSD is affecting results in an acceptable manner.

Does regional anaesthesia improve outcome after total hip arthroplasty? A systematic review.

Total hip arthroplasty (THA) is amenable to a variety of regional anaesthesia (RA) techniques that may improve patient outcome. We sought to answer whether RA decreased mortality, cardiovascular morbidity, deep venous thrombosis (DVT) and pulmonary embolism (PE), blood loss, duration of surgery, pain, opioid-related adverse effects, cognitive defects, and length of stay. We also questioned whether RA improved rehabilitation. To do so, we performed a systematic review of the contemporary literature to compare general anaesthesia (GA) and RA and also systemic and regional analgesia for THA. To reflect contemporary surgical and anaesthetic practice, only randomized controlled trials (RCTs) from 1990 onward were included. We identified 18 studies involving 1239 patients. Only two of the 18 trials were of Level I quality. There is insufficient evidence from RCTs alone to conclude if anaesthetic technique influenced mortality, cardiovascular morbidity, or the incidence of DVT and PE when using thromboprophylaxis. Blood loss may be reduced in patients receiving RA rather than GA for THA. Our review suggests that there is no difference in duration of surgery in patients who receive GA or RA. Compared with systemic analgesia, regional analgesia can reduce postoperative pain, morphine consumption, and nausea and vomiting. Length of stay is not reduced and rehabilitation does not appear to be facilitated by RA or analgesia for THA.

High performance liquid chromatography of polyolefin plastomers/elastomers (ethylene/1-octene copolymers) - Comparison of different solvent systems.

A series of ethylene/1-octene copolymers with different chemical composition was separated in six binary mobile phases using solvent gradients and a column packed with porous graphite Hypercarb™. It was found that the elution volumes of the samples were to a larger extent influenced by the choice of desorption promoting solvent (desorli: 1,2-dichlorobenzene vs. 1,2,4-trichlorobenzene) than by the choice of adsorption promoting solvent (2-ethyl-1-hexanol, 1-decanol, n-decane). Elution volumes increased with decreasing number of chlorine atoms in the desorlis as well as with increasing polarity of the adsorlis. The resolution of HPLC systems depended pronouncedly on the choice of solvent pair: While in the majority of the tested HPLC systems, the chromatograms of the polymer samples indicate a shoulder, in n-decane→TCB the samples eluted without indication of a shoulder. In addition to the influence of different solvents on the samples elution behavior, the response of the employed detector, an evaporative light scattering detector (ELSD), was investigated. Its response was found to depend pronouncedly on the nature of the used solvents. Overall, the solvent pair 1-decanol→TCB appears to be the optimal compromise between the considered parameters and thus the best choice for HPLC of ethylene/1-octene copolymers.