James Paul

Femoral nerve block improves analgesia outcomes after total knee arthroplasty: a meta-analysis of randomized controlled trials.

Background:Femoral nerve blockade (FNB) is a common method of analgesia for postoperative pain control after total knee arthroplasty. We conducted a systematic review to compare the analgesia outcomes in randomized controlled trials that compared FNB (with and without sciatic nerve block) with epidural and patient-controlled analgesia (PCA). Methods:We identified 23 randomized controlled trials that compared FNB with PCA or epidural analgesia. These studies included 1,016 patients, 665 with FNB, 161 with epidural, and 190 with PCA alone. Results:All 10 studies of single-shot FNB (SSFNB) used concurrent PCA opioids. SSFNB was found to reduce PCA morphine consumption at 24 h (−19.9 mg, 95% credible interval [CrI]: −35.2 to −4.6) and 48 h (−38.0 mg, 95% CrI: −56.0 to −19.7), pain scores with activity (but not at rest) at 24 and 48 h (−1.8 visual analog pain scale, 95% CrI: −3.3 to −0.02 at 24 h; −1.5 visual analog pain scale, 95% CrI: −2.9 to −0.02 at 48 h) and reduce the incidence of nausea (0.37 odds ratio, 95% CrI: 0.1 to 0.9) compared with PCA alone. SSFNB had similar morphine consumption and pain scores compared with SSFNB plus sciatic nerve block, and SSFNB plus continuous FNB. Conclusions:SSFNB or continuous FNB (plus PCA) was found to be superior to PCA alone for postoperative analgesia for patients having total knee arthroplasty. The impact of adding a sciatic block or continuous FNB to a SSFNB needs to be studied further.

Deliberate hypotension in orthopedic surgery reduces blood loss and transfusion requirements: A meta-analysis of randomized controlled trials

PurposeTo determine if deliberate hypotension decreases blood loss and transfusion requirements in patients undergoing orthopedic surgery, a systematic review of all randomized trials addressing this issue was undertaken.MethodsElectronic databases, citations lists and review articles were searched for potential articles. Relevant articles met the following inclusion criteria: English language, humans undergoing orthopedic surgery, deliberate hypotension used by any method, intraoperative blood loss measured as an outcome, and the trial methodology being randomized and controlled. Four outcomes were analyzed, including estimated blood loss, blood transfused, surgery duration, and quality of the surgical field. For all analyses, the random-effects model was used.ResultsSeventeen articles met the inclusion criteria. The surgeries studied included total hip arthroplasty (seven), orthog-nathic surgery (eight), total knee arthroplasty (one) and spinal fusion (one). A total of 636 patients were randomized across all studies. For blood loss, the overall weighted mean difference favoured treatment, with a savings of about 287 mL of blood [95% confidence interval (CI): -447, -127]. The mean differences also showed a statistically significant benefit for deliberate hypotension in reducing transfusion requirements (-667 mL of blood transfused; 95% CI: -963, -370). Deliberate hypotension was not shown to reduce the duration of surgery (-1.9 min of surgery; 95% CI: -7.2, 3.5) or improve surgical conditions (surgical field quality rating -0.5; 95% CI: -1.1, 0.2).ConclusionThis review provides some support for the use of deliberate hypotension in reducing blood loss and transfusion requirements in orthopedic surgery, but these results are tempered by the small sample sizes and poor methodological quality of published studies.RésuméObjectifAfin de déterminer si l’hypotension délibérée réduit les pertes sanguines et l’incidence transfusionnelle chez les patients subissant une chirurgie orthopédique, un compte-rendu systéma-tique de toutes les études randomisées traitant de cette question a été entrepris.MéthodeLes bases de données électroniques, listes de citations et articles de compte-rendu ont été consultés afin de trouver des articles potentiellement pertinents. Les articles pertinents ont répondu aux critères suivants: langue anglaise, êtres humains subissant une chirurgie orthopédique, utilisation d’une méthode d’hypotension délibérée, quelle qu’elle soit, pertes sanguines pero-pératoires mesurées en tant que résultat, et méthodologie d’étude randomisée et contrôlée. Quatre évolutions ont été analysées, notamment les pertes sanguines estimées, le sang transfusé, la durée de la chirurgie et la qualité de l’hémostase chirurgicale. Un modèle à effets aléatoires a été utilisé pour toutes les analyses.RésultatsDix-sept articles ont répondu aux critères d’inclusion. Les chirurgies évaluées comprenaient: arthroplasties totales de la hanche (sept), chirurgies orthognathes (huit), arthroplastie totale du genou (une) et spondylodèse (une). Un total de 636 patients ont été randomisés dans ces études. En ce qui a trait à la perte sanguine, la différence moyenne pondérée totale a montré un résultat en faveur du traitement, avec une diminution des pertes sanguines d’environ 287 mL [95 % intervalle de confiance (IC) : 447, -127]. Les différences moyennes ont également montré que l’hypotension délibérée présente des bienfaits statistiquement si-gnificatifs dans la réduction de l’incidence transfusionnelle (-667 mL de sang transfusé; 95 % IC: -963, -370). L’hypotension délibérée n’a pas eu d’influence sur la durée de chirurgie (-1,9 min de chirurgie; 95 % IC: -7,2, 3,5) ou sur l’ amélioration des conditions chirurgicales (évaluation de la qualité de l’hémostase chirurgicale -0,5 ;95%IC:-1,1, 0,2).ConclusionCe compte-rendu soutient dans une certaine mesure l’utilisation de l’hypotension délibérée pour réduire les pertes sanguines et l’incidence transfusionnelle lors de chirurgie ortho-pédique; toutefois, ces résultats sont mitigés par les petites tailles d’échantillons et la pauvreté méthodologique des études publiées.

Sudden Death from Asthma in 108 Children and Young Adults

To identify factors that may contribute to asthma mortality, 108 acute asthma deaths were reviewed. Information was obtained from medical records, next-of-kin, and autopsy records. The fatal asthmatic was characterized by early-onset asthma, severe disease requiring systemic corticosteroids, and prior hospitalization. Risk factors associated with gender, season, employment, and region were also identified. The fatal attack was characterized by an identifiable trigger, delay in seeking medical attention, and rapid deterioration in clinical status. Death due to asthma was confirmed in 95% of autopsied cases. Adrenal cortical abnormalities were recorded for 18.7% of cases. We conclude that, in addition to established risk factors, complications associated with the use of systemic steroids may contribute to the risk for sudden death in this age group.

Neuraxial block, death and serious cardiovascular morbidity in the POISE trial

BACKGROUND This post hoc analysis aimed to determine whether neuraxial block was associated with a composite of cardiovascular death, non-fatal myocardial infarction (MI) and non-fatal cardiac arrest within 30 days of randomization in POISE trial patients. METHODS A total of 8351 non-cardiac surgical patients at high risk of cardiovascular complications were randomized to β-blocker or placebo. Neuraxial block was defined as spinal, lumbar or thoracic epidural anaesthesia. Logistic regression, with weighting using estimated propensity scores, was used to determine the association between neuraxial block and primary and secondary outcomes. RESULTS Neuraxial block was associated with an increased risk of the primary outcome [287 (7.3%) vs 229 (5.7%); odds ratio (OR), 1.24; 95% confidence interval (CI), 1.02-1.49; P=0.03] and MI [230 (5.9%) vs 177 (4.4%); OR, 1.32; 95% CI, 1.07-1.64; P=0.009] but not stroke [23 (0.6%) vs 32 (0.8%); OR, 0.76; 95% CI, 0.44-1.33; P=0.34], death [96 (2.5%) vs 111 (2.8%); OR, 0.87; 95% CI, 0.65-1.17; P=0.37] or clinically significant hypotension [522 (13.4%) vs 484 (12.1%); OR, 1.13; 95% CI, 0.99-1.30; P=0.08]. Thoracic epidural with general anaesthesia was associated with a worse primary outcome than general anaesthesia alone [86 (12.1%) vs 119 (5.4%); OR, 2.95; 95% CI, 2.00-4.35; P<0.001]. CONCLUSIONS In patients at high risk of cardiovascular morbidity, neuraxial block was associated with an increased risk of adverse cardiovascular outcomes, which could be causal or because of residual confounding.

Withholding versus Continuing Angiotensin-converting Enzyme Inhibitors or Angiotensin II Receptor Blockers before Noncardiac Surgery: An Analysis of the Vascular events In noncardiac Surgery patIents cOhort evaluatioN Prospective Cohort.

Background: The effect on cardiovascular outcomes of withholding angiotensin-converting enzyme inhibitors or angiotensin II receptor blockers in chronic users before noncardiac surgery is unknown. Methods: In this international prospective cohort study, the authors analyzed data from 14,687 patients (including 4,802 angiotensin-converting enzyme inhibitor/angiotensin II receptor blocker users) at least 45 yr old who had in-patient noncardiac surgery from 2007 to 2011. Using multivariable regression models, the authors studied the relationship between withholding angiotensin-converting enzyme inhibitors/angiotensin II receptor blockers and a primary composite outcome of all-cause death, stroke, or myocardial injury after noncardiac surgery at 30 days, with intraoperative and postoperative clinically important hypotension as secondary outcomes. Results: Compared to patients who continued their angiotensin-converting enzyme inhibitors/angiotensin II receptor blockers, the 1,245 (26%) angiotensin-converting enzyme inhibitor/angiotensin II receptor blocker users who withheld their angiotensin-converting enzyme inhibitors/angiotensin II receptor blockers in the 24 h before surgery were less likely to suffer the primary composite outcome of all-cause death, stroke, or myocardial injury (150/1,245 [12.0%] vs. 459/3,557 [12.9%]; adjusted relative risk, 0.82; 95% CI, 0.70 to 0.96; P = 0.01) and intraoperative hypotension (adjusted relative risk, 0.80; 95% CI, 0.72 to 0.93; P < 0.001). The risk of postoperative hypotension was similar between the two groups (adjusted relative risk, 0.92; 95% CI, 0.77 to 1.10; P = 0.36). Results were consistent across the range of preoperative blood pressures. The practice of withholding angiotensin-converting enzyme inhibitors/angiotensin II receptor blockers was only modestly correlated with patient characteristics and the type and timing of surgery. Conclusions: Withholding angiotensin-converting enzyme inhibitors/angiotensin II receptor blockers before major noncardiac surgery was associated with a lower risk of death and postoperative vascular events. A large randomized trial is needed to confirm this finding. In the interim, clinicians should consider recommending that patients withhold angiotensin-converting enzyme inhibitors/angiotensin II receptor blockers 24 h before surgery.

Characterization of airborne mineral dusts associated with farming activities in rural Alberta, Canada.

SummaryThe dry and windy climate of the Western Canadian prairie provinces, combined with large scale agricultural acitivities, results in aerosolization or organic and mineral dusts. The purpose of this study was to conduct an environmental and minerological analysis of these dusts in order to estimate the risk for pneumoconiosis in exposed farmer populations. Two districts in central/southern Alberta were chosen for study. One of these regions was representative of a predominantly grain growing district with minimal use of irrigation; the other region was largely devoted to forage and irrigated crop production. Air pollution statistics showed a bi-modal distribution of total suspended particulates (TSP) with peaks corresponding with maximal farm activities in the spring and early fall. Analysis of bulk dust samples obtained from tractor cab filters showed that the majority of particles from both districts were within the respirable range (< 5 gm). Samples from the forage-crop region contained more organic material, a greater water soluble fraction and had particles that were, on average, smaller and rounder than particles from the grain district. These differences were thought to reflect differences in irrigation patterns and use of fertilizers between the two districts. Free silica (quartz) content was also very variable and ranged from 1 to 17% on a mass basis. Respirable fibrous minerals were occasionally identified, however, no asbestos fibres, fibrous tremolite, or fibrous zeolites were identified. The results indicate that there is potential risk for mineral dust pneumoconiosis in heavily exposed farmer populations and that this risk will be influenced by local and regional factors.

Empirical comparison of four baseline covariate adjustment methods in analysis of continuous outcomes in randomized controlled trials

Background Although seemingly straightforward, the statistical comparison of a continuous variable in a randomized controlled trial that has both a pre- and posttreatment score presents an interesting challenge for trialists. We present here empirical application of four statistical methods (posttreatment scores with analysis of variance, analysis of covariance, change in scores, and percent change in scores), using data from a randomized controlled trial of postoperative pain in patients following total joint arthroplasty (the Morphine COnsumption in Joint Replacement Patients, With and Without GaBapentin Treatment, a RandomIzed ControlLEd Study [MOBILE] trials). Methods Analysis of covariance (ANCOVA) was used to adjust for baseline measures and to provide an unbiased estimate of the mean group difference of the 1-year postoperative knee flexion scores in knee arthroplasty patients. Robustness tests were done by comparing ANCOVA with three comparative methods: the posttreatment scores, change in scores, and percentage change from baseline. Results All four methods showed similar direction of effect; however, ANCOVA (−3.9; 95% confidence interval [CI]: −9.5, 1.6; P=0.15) and the posttreatment score (−4.3; 95% CI: −9.8, 1.2; P=0.12) method provided the highest precision of estimate compared with the change score (−3.0; 95% CI: −9.9, 3.8; P=0.38) and percent change (−0.019; 95% CI: −0.087, 0.050; P=0.58). Conclusion ANCOVA, through both simulation and empirical studies, provides the best statistical estimation for analyzing continuous outcomes requiring covariate adjustment. Our empirical findings support the use of ANCOVA as an optimal method in both design and analysis of trials with a continuous primary outcome.

Nitrous Oxide and Serious Morbidity and Mortality in the POISE Trial

BACKGROUND:In this post hoc subanalysis of the Perioperative Ischemic Evaluation (POISE) trial, we sought to determine whether nitrous oxide was associated with the primary composite outcome of cardiovascular death, nonfatal myocardial infarction (MI), and nonfatal cardiac arrest within 30 days of randomization. METHODS:The POISE trial of perioperative &bgr;-blockade was undertaken in 8351 patients. Nitrous oxide anesthesia was defined as the coadministration of nitrous oxide in patients receiving general anesthesia, with or without additional neuraxial blockade or peripheral nerve blockade. Logistic regression, with inverse probability weighting using estimated propensity scores, was used to determine the association of nitrous oxide with the primary outcome, MI, stroke, death, and clinically significant hypotension. RESULTS:Nitrous oxide was administered to 1489 (29%) of the 5133 patients included in this analysis. Nitrous oxide had no significant effect on the risk of the primary outcome (112 [7.5%] vs 248 [6.9%]; odds ratio [OR], 1.08; 95% confidence interval [CI], 0.82–1.44; 99% CI, 0.75–1.57; P = 0.58), MI (89 [6.0] vs 204 [5.6]; OR, 0.99; 95% CI, 0.75–1.31; 99% CI, 0.69–1.42; P = 0.94), stroke (6 [0.4%] vs 28 [0.8%]; OR, 0.85; 95% CI, 0.26–2.82; 99% CI, 0.17–4.11; P = 0.79), death (40 [2.7%] vs 100 [2.8%]; OR, 1.04; 95% CI, 0.6–1.81; 99% CI, 0.51–2.15; P = 0.88) or clinically significant hypotension (219 [14.7%] vs 544 [15.0%]; OR, 0.92; 95% CI, 0.74–1.15; 99% CI, 0.70–1.23; P = 0.48). CONCLUSIONS:In this post hoc subanalysis, nitrous oxide was not associated with an increased risk of adverse outcomes in the POISE trial patients. This analysis was limited by the observational nature of the data and the lack of information on the concentration and duration of nitrous oxide administration. Further randomized controlled trial evidence is required.

Morphine overdose from error propagation on an acute pain service.

PurposeTo highlight a case in which multiple errors occurred during programming and administration of analgesia via a patient-controlled analgesia (PCA) pump, and to formulate recommendations on how to avoid such errors in the future.Clinical featuresFollowing lumbar surgery, a 43-yr-old woman was switched from epidural analgesia to a PCA pump. This change was associated with numerous errors at several points of delivery of her care. Errors included incorrect connection of the PCA adapter, incorrect pump programming, and communication lapses which resulted in a morphine overdose and subsequent respiratory arrest. The patient was promptly resuscitated, and she had an uneventful recovery. The event resulted in a complete review of pain management equipment and the training and education of staff using this equipment at our institution.ConclusionThis case highlights how multiple individual errors can combine to result in a serious adverse event. While equipment design was an important factor in this adverse event, human factors played a critical role at multiple levels.RésuméObjectifPrésenter un cas où de multiples erreurs sont survenues pendant la programmation et ľadministration de ľanalgésie autocontrôlée (AAC) et formuler des recommandations sur les moyens ďéviter ces erreurs à ľavenir.Éléments cliniquesAprès une intervention chirurgicale lombaire, ľanalgésie péridurale a été remplacée par une pompe ďAAC chez une femme de 43 ans. Ce changement a été suivi de nombreuses erreurs dont la connexion incorrecte de ľadaptateur ďAAC, une programmation inexacte de la pompe et des omissions dans les communication qui ont mené à une surdose de morphine et à un arrêt respiratoire subséquent. La patiente, rapidement réanimée, s’est bien rétablie. Cet événement a conduit à ľexamen complet du matériel de traitement de la douleur et à la formation et à ľéducation du personnel qui utilise le matériel dans notre institution.ConclusionCe cas souligne comment de multiples erreurs individuelles peuvent, en se combinant, provoquer un grave événement indésirable. La conception du matériel a été un facteur important, mais des facteurs humains y ont joué un rôle critique.

Pulsed radiofrequency treatment of the lumbar dorsal root ganglion in patients with chronic lumbar radicular pain: a randomized, placebo-controlled pilot study

Background No proof of efficacy, in the form of a randomized controlled trial (RCT), exists to support pulsed radiofrequency (PRF) treatment of the dorsal root ganglion (DRG) for chronic lumbar radicular (CLR) pain. We determined the feasibility of a larger trial (primary objective), and also explored the efficacy of PRF in decreasing pain on a visual analog scale (VAS) and improving the Oswestry Disability Index. Methods This was a single-center, placebo-controlled, triple-blinded RCT. Patients were randomized to a placebo group (needle placement) or a treatment group (PRF at 42°C for 120 seconds to the DRG). Patients were followed up for 3 months post procedure. Outcomes with regard to pain, Oswestry Disability Index score, and side effects were analyzed on an intention-to-treat basis. Results Over 15 months, 350 potential patients were identified and 56 were assessed for eligibility. Fifteen of them did not meet the selection criteria. Of the 41 eligible patients, 32 (78%) were recruited. One patient opted out before intervention. Three patients were lost to follow-up at 3 months. Mean VAS differences were not significantly different at 4 weeks (−0.36, 95% confidence interval [CI], −2.29, 1.57) or at 3 months (−0.76, 95% CI, −3.14, 1.61). The difference in mean Oswestry Disability Index score was also not significantly different at 4 weeks (−2%, 95% CI, −14%, 10%) or 3 months (−7%, 95% CI, −21%, 6%). There were no major side effects. Six of 16 patients in the PRF group and three of 15 in the placebo group showed a >50% decrease in VAS score. Conclusion The recruitment rate was partially successful. At 3 months, the relative success of PRF-DRG was small. A large-scale trial to establish efficacy is not practically feasible considering the small effect size, which would necessitate recruitment of a challengingly large number of participants over a number of years. Until clear parameters for application of PRF are established, clinicians will need to use their individual judgment regarding its clinical applicability, given the present evidence.