Paul Zufferey

Effects of nonsteroidal antiinflammatory drugs on patient-controlled analgesia morphine side effects: meta-analysis of randomized controlled trials

Nonsteroidal antiinflammatory drugs (NSAIDs) are commonly combined with intravenous morphine patient-controlled analgesia to relieve postoperative pain. NSAIDs have a documented 30–50% sparing effect on morphine consumption. However, most of the studies have not demonstrated a decrease in morphine adverse effects. A meta-analysis of randomized controlled trials was performed to evaluate the risk of morphine adverse effects in patients treated with NSAIDs. Twenty-two prospective, randomized, double-blind studies including 2,307 patients were selected. NSAIDs decreased significantly postoperative nausea and vomiting by 30%, nausea alone by 12%, vomiting alone by 32% and sedation by 29%. A regression analysis yielded findings indicating that morphine consumption was positively correlated with the incidence of nausea and vomiting. Pruritus, urinary retention, and respiratory depression were not significantly decreased by NSAIDs.

Do Antifibrinolytics Reduce Allogeneic Blood Transfusion in Orthopedic Surgery

Studies have shown that antifibrinolytic (aprotinin, tranexamic acid, or ϵ-aminocaproic acid) reduce blood loss in orthopedic surgery. However, most lacked sufficient power to evaluate the efficacy and safety on clinical outcomes. This meta-analysis aims to evaluate whether intravenous antifibrinolytics, when compared with placebo, reduce perioperative allogeneic erythrocyte transfusion requirement in adults undergoing orthopedic surgery and whether it might increase the risk of venous thromboembolism. From MEDLINE, EMBASE, and the Cochrane Controlled Trials Register, the authors identified 43 randomized controlled trials in total hip and knee arthroplasty, spine fusion, musculoskeletal sepsis, or tumor surgery performed to July 2005 (for aprotinin, 23 trials with 1,268 participants; tranexamic acid, 20 with 1,084; ϵ-aminocaproic acid, 4 with 171). Aprotinin and tranexamic acid reduced significantly the proportion of patients requiring allogeneic erythrocyte transfusion according to a transfusion protocol. The odds ratio was 0.43 (95% confidence interval, 0.28–0.64) for aprotinin and 0.17 (0.11–0.24) for tranexamic acid. Results suggest a dose–effect relation with tranexamic acid. ϵ-Aminocaproic acid was not efficacious. Unfortunately, data were too limited for any conclusions regarding safety. Although the results suggest that aprotinin and tranexamic acid significantly reduce allogeneic erythrocyte transfusion, further evaluation of safety is required before recommending the use of antifibrinolytics in orthopedic surgery.

A semi-mechanistic absorption model to evaluate drug–drug interaction with dabigatran: application with clarithromycin

AIM The aim of this study was to develop a PK/PD model to assess drug-drug interactions between dabigatran and P-gp modulators, using the example of clarithromycin, a strong inhibitor of P-gp. METHODS Ten healthy male volunteers were randomized to receive in the first treatment period a single 300 mg dose of dabigatran etexilate (DE) and in the second treatment period 500 mg clarithromycin twice daily during 3 days and then 300 mg DE plus 500 mg clarithromycin on the fourth day, or the same treatments in the reverse sequence. Dabigatran plasma concentration and ecarin clotting time (ECT) were measured on 11 blood samples. Models were built using a non-linear mixed effect modelling approach. RESULTS The best PK model was based on an inverse Gaussian absorption process with two compartments. The relationship between dabigatran concentration and ECT was implemented as a linear function. No continuous covariate was associated with a significant decrease in the objective function. The concomitant administration of clarithromycin induced a significant change only in DE bioavailability, which increased from 6.5% to 10.1% in the presence of clarithromycin. Clarithromycin increased peak concentration and AUC by 60.2% and 49.1% respectively. CONCLUSION The model proposed effectively describes the complex PK of dabigatran and takes into account drug-drug interactions with P-gp activity modulators, such as clarithromycin.

Cervical epidural anesthesia is associated with increased cancer-free survival in laryngeal and hypopharyngeal cancer surgery: a retrospective propensity-matched analysis.

Background and Objectives Regional anesthesia preserves perioperative immune competence and may reduce the risk of recurrence and metastasis after cancer surgery. Cervical epidural anesthesia provides adequate analgesia for head and neck cancer surgery, but its impact on cancer recurrence is unknown. Methods This study was a single-center retrospective cohort study of patients undergoing larynx or hypopharynx cancer surgery between January 1984 and December 2008. One hundred eleven patients had general anesthesia combined with intraoperative and postoperative cervical epidural; 160 had general anesthesia alone with postoperative morphine. From this cohort, matched pairs were selected using a propensity score to balance potential confounders of receiving epidural anesthesia. The primary end point was the length of cancer-free survival after surgery until September 2009. Results Propensity-based matching produced 65 pairs. Matching was effective in achieving balance between groups for each of the preoperative variables collected. Combined epidural and general anesthesia (68% 5-year cancer-free survival; 95% confidence interval [CI], 57%–82%) was associated with significantly increased cancer-free survival compared with general anesthesia alone (37% 5-year cancer-free survival; 95% CI, 25%–54%) with a corresponding adjusted hazard ratio of 0.49 (95% CI, 0.25–0.96; P = 0.04). Patients in the epidural group had an increased overall survival compared with the non–epidural group (P = 0.03). Conclusions The association between cervical epidural anesthesia and increased cancer-free survival found in this retrospective study should be an important hypothesis to further investigate in head and neck cancer surgery.

Optimal low-molecular-weight heparin regimen in major orthopaedic surgery A meta-analysis of randomised trials

Low-molecular-weight heparins (LMWH) are routinely used for thromboprophylaxis in major lower limb orthopaedic surgery. However the optimal LMWH regimen, offering the greatest efficacy with an acceptable risk of bleeding, has not been clearly established with regard to dose and timing of treatment initiation. We performed a meta-analysis of all available randomised trials comparing LMWH to placebo. Relative risks (RR) and corresponding 95% confidence intervals (CI) were calculated. By means of subgroup analysis, we evaluated the consistency of the results according to the timing of treatment initiation (preoperative versus postoperative) and dose of LMWH used (low doses, i.e. 4000 anti-Xa IU or below versus high doses). The possibility of a dose-effect relationship of LMWH was also evaluated by meta-regression. Thirteen studies were included (1925 patients). In four studies, LMWH treatment was started postoperatively. Daily LMWH doses ranged from 3000 anti-Xa IU to over 6000 anti-Xa IU. Compared to placebo, LMWH significantly reduced the risk of asymptomatic deep-vein thrombosis (DVT) (RR=0.51, 95% CI=[0.45-0.59], p<0.001) without significantly increasing the risk of major haemorrhage (RR=0.80 [0.36-1.79], p=0.58). We found no convincing evidence that starting prophylaxis preoperatively was associated with a significantly reduced risk of asymptomatic DVT relative to starting postoperatively. Our results showed a strong correlation between the risk of DVT and LMWH dose (meta-regression, test of slope p=0.03). These findings are tentative because the comparisons are across trials, but nevertheless suggest that the different LMWH regimens currently recommended are effective and safe.

Ultra-performance LC MS/MS method for quantification of clopidogrel active metabolite

A sensible ultra-performance LC-MS method was developed and validated for the quantification of clopidogrel active metabolite in human plasma, with clopidogrel D4 as internal standard. Plasma pretreatment involved a one-step protein precipitation with acetonitrile. The separation was performed by reverse-phase chromatography on a C8 column. The method was linear over the concentration range of 1-150 ng/mL. The intra- and inter-day precision values were below 17% and accuracy was from 1.7 to 7.5% at all quality control levels. The lower LOQ was 0.8 ng/mL. Sample analysis time was reduced to 5 min including sample preparation (limited to protein precipitation). The present method was successfully applied to a clopidogrel active metabolite pharmacokinetic study following oral administration to healthy volunteers.

Quantification of total and unbound tranexamic acid in human plasma by ultrafiltration liquid chromatography/tandem mass spectrometry: Application to pharmacokinetic analysis

The present work describes the development and validation of rapid, sensitive and accurate liquid chromatography method, coupled with tandem mass spectrometry detection, for quantification of tranexamic acid in human plasma using isotopically labeled internal standard (IS). A one-step plasma protein precipitation was performed with acetonitrile. UPLC BEH amide column was used for chromatographic separation. Tranexamic acid and IS were detected in multiple reaction monitoring in electrospray positive ionization. The method was linear over the concentration range of 0.8-200mg/L. The intra- and inter-day precision values were below 11.5% and accuracy was better than 9.6%. Total analysis time was reduced to 6min including sample preparation. The present method was successfully applied to pharmacokinetic pilot study in patients undergoing orthopedic surgery. Ultrafiltration allowed confirming the weak binding to plasma proteins and confirming that total plasma TXA concentration is measured by this assay.

Intravenous Tranexamic Acid Bolus plus Infusion Is Not More Effective than a Single Bolus in Primary Hip Arthroplasty: A Randomized Controlled Trial

Background: Preoperative administration of the antifibrinolytic agent tranexamic acid reduces bleeding in patients undergoing hip arthroplasty. Increased fibrinolytic activity is maintained throughout the first day postoperation. The objective of the study was to determine whether additional perioperative administration of tranexamic acid would further reduce blood loss. Methods: This prospective, double-blind, parallel-arm, randomized, superiority study was conducted in 168 patients undergoing unilateral primary hip arthroplasty. Patients received a preoperative intravenous bolus of 1 g of tranexamic acid followed by a continuous infusion of either tranexamic acid 1 g (bolus-plus-infusion group) or placebo (bolus group) for 8 h. The primary outcome was calculated perioperative blood loss up to day 5. Erythrocyte transfusion was implemented according to a restrictive transfusion trigger strategy. Results: The mean perioperative blood loss was 919 ± 338 ml in the bolus-plus-infusion group (84 patients analyzed) and 888 ± 366 ml in the bolus group (83 patients analyzed); mean difference, 30 ml (95% CI, −77 to 137; P = 0.58). Within 6 weeks postsurgery, three patients in each group (3.6%) underwent erythrocyte transfusion and two patients in the bolus group experienced distal deep-vein thrombosis. A meta-analysis combining data from this study with those of five other trials showed no incremental efficacy of additional perioperative administration of tranexamic acid. Conclusions: A preoperative bolus of tranexamic acid, associated with a restrictive transfusion trigger strategy, resulted in low erythrocyte transfusion rates in patients undergoing hip arthroplasty. Supplementary perioperative administration of tranexamic acid did not achieve any further reduction in blood loss.

Indirect comparison meta-analysis of two enoxaparin regimens in patients undergoing major orthopaedic surgery. Impact on the interpretation of thromboprophylactic effects of new anticoagulant drugs.

Two enoxaparin dosage regimens are used as comparators to evaluate new anticoagulants for thromboprophylaxis in patients undergoing major orthopaedic surgery, but so far no satisfactory direct comparison between them has been published. Our objective was to compare the efficacy and safety of enoxaparin 3,000 anti-Xa IU twice daily and enoxaparin 4,000 anti-Xa IU once daily in this clinical setting by indirect comparison meta-analysis, using Buchers method. We selected randomised controlled trials comparing another anticoagulant, placebo (or no treatment) with either enoxaparin regimen for venous thromboembolism prophylaxis after hip or knee replacement or hip fracture surgery, provided that the second regimen was assessed elsewhere versus the same comparator. Two authors independently evaluated study eligibility, extracted the data, and assessed the risk of bias. The primary efficacy outcome was the incidence of venous thomboembolism. The main safety outcome was the incidence of major bleeding. Overall, 44 randomised comparisons in 56,423 patients were selected, 35 being double-blind (54,117 patients). Compared with enoxaparin 4,000 anti-Xa IU once daily, enoxaparin 3,000 anti-Xa IU twice daily was associated with a reduced risk of venous thromboembolism (relative risk [RR]: 0.53, 95% confidence interval [CI]: 0.40 to 0.69), but an increased risk of major bleeding (RR: 2.01, 95% CI: 1.23 to 3.29). In conclusion, when interpreting the benefit-risk ratio of new anticoagulant drugs versus enoxaparin for thromboprophylaxis after major orthopaedic surgery, the apparently greater efficacy but higher bleeding risk of the twice-daily 3,000 anti-Xa IU enoxaparin regimen compared to the once-daily 4,000 anti-Xa IU regimen should be taken into account.

Quality of Life After Cardiac Surgery Based on the Minimal Clinically Important Difference Concept

BACKGROUND Health-related quality of life (HRQOL) is an increasingly important issue in assessing the consequences of any surgical or medical intervention. Our study aimed to evaluate change in HRQOL 6 months after elective cardiac operations and to identify specific predictors of poor HRQOL. METHODS In this prospective, single-center study, HRQOL was evaluated before and 6 months after the operation using the Medical Outcome Study 36-Item Short Form Health Survey questionnaire and its two components: the Physical Component Summary and the Mental Component Summary. We distinguished patients with worsening of HRQOL according to the minimal clinically important difference. All consecutive adult patients undergoing cardiac operations were included. RESULTS The preoperative and postoperative 36-Item Short Form Health Survey questionnaires were completed by 326 patients, and 24 patients died before completing follow-up questionnaires. On the basis of the definition used, clinically significant deterioration of HRQOL was observed in 93 patients (26.6%) for the Physical Component Summary and in 99 patients (28.2%) for the Mental Component Summary. Renal replacement for acute renal failure and mechanical ventilation for longer than 48 hours were independent risk factors for Physical Component Summary and Mental Component Summary worsening or death. CONCLUSIONS Although our study showed overall improvement of quality of life after cardiac operations, more than one-quarter of the patients manifested deterioration of HRQOL at 6 months postoperatively. The findings from this study should help clinicians to inform patients about their likely postoperative functional status and quality of life.