Reducing rebound pain severity after arthroscopic shoulder surgery under general anesthesia and interscalene block: a two-centre randomized controlled trial of pre-emptive opioid treatment compared with placebo.

PURPOSE: Although a single-injection interscalene block provides effective early postoperative analgesia following shoulder surgery, patients may experience "rebound pain" when the block resolves. Our objective was to determine if oral hydromorphone (2 mg) given six hours after a single-injection interscalene block for arthroscopic shoulder surgery leads to a clinically significant reduction in the severity of rebound pain. METHODS: After approval from research ethics boards, we conducted a two-centre, parallel-group, double-blind, randomized, placebo-controlled superiority trial. Patients received preoperative interscalene block, general anesthesia, and either hydromorphone or placebo six hours after the block. The primary outcome was the worst pain score in the first 24 hr postoperatively, measured on an 11-point (0-10) numerical rating scale. RESULTS: A total of 73 participants were randomly assigned to either the hydromorphone or placebo group. There was no statistically significant difference in the mean (standard deviation) worst pain score within 24 hr between the hydromorphone and placebo groups (6.5 [2.4] vs 5.9 [2.3]; mean difference, 0.6; 95% confidence interval, -0.5 to 1.8). Similarly, we did not find any significant difference in the pain trajectory, opioid use, or incidence of nausea and vomiting between the groups. The mean time to worst pain was 14.6 hr, and the mean time to first rescue analgesia was 11.3 hr after interscalene block. CONCLUSION: Hydromorphone 2 mg given six hours after interscalene block did not reduce the severity of rebound pain postoperatively compared with placebo in patients undergoing arthroscopic shoulder surgery. STUDY REGISTRATION: ClinicalTrials.gov (NCT02939209); registered 19 October 2016.

RéSUMé: OBJECTIF: Bien qu'un bloc interscalénique à injection unique fournisse une analgésie postopératoire précoce efficace après une chirurgie de l'épaule, les patient·es peuvent ressentir une « douleur de rebond ¼ lorsque le bloc se résorbe. Notre objectif était de déterminer si l'hydromorphone orale (2 mg) administrée six heures après une injection unique de bloc interscalénique pour une chirurgie arthroscopique de l'épaule entraînait une réduction cliniquement significative de la gravité de la douleur de rebond. MéTHODE: Après l'approbation des comités d'éthique de la recherche, nous avons mené une étude de supériorité dans deux centres, en groupes parallèles, à double insu, randomisée et contrôlée par placebo. Les patient·es ont reçu un bloc interscalénique préopératoire, une anesthésie générale et de l'hydromorphone ou un placebo six heures après le bloc. Le critère d'évaluation principal était le pire score de douleur au cours des premières 24 heures postopératoires, mesuré sur une échelle d'évaluation numérique de 11 points (0 à 10). RéSULTATS: Au total, 73 personnes ont participé à l'étude et ont été aléatoirement assignées au groupe hydromorphone ou au groupe placebo. Il n'y avait pas de différence statistiquement significative dans le score moyen (écart type) de la pire douleur dans les 24 heures entre les groupes hydromorphone et placebo (6,5 [2,4] vs 5,9 [2,3]; différence moyenne, 0,6; intervalle de confiance à 95 %, −0,5 à 1,8). De même, nous n'avons trouvé aucune différence significative dans la trajectoire de la douleur, la consommation d'opioïdes ou l'incidence de nausées et vomissements entre les groupes. Le temps moyen jusqu'à la pire douleur était de 14,6 heures, et le temps moyen jusqu'à la première analgésie de secours était de 11,3 heures après le bloc interscalénique. CONCLUSION: L'hydromorphone 2 mg administrée six heures après le bloc interscalénique n'a pas réduit la gravité de la douleur de rebond postopératoire par rapport au placebo chez les patient·es bénéficiant d'une chirurgie arthroscopique de l'épaule. ENREGISTREMENT DE L'éTUDE: ClinicalTrials.gov (NCT02939209); enregistrée le 19 octobre 2016.

Investigating predictors of problematic alcohol, cannabis, and nicotine use among legal users of all three substances.

Background: The three most used substances-alcohol, cannabis, and nicotine-are frequently concurrently. Use of each substance has been connected to an increased probability of use of the other substances, and the problematic use of each substance has been linked to demographic factors, substance use factors, and personality. However, little is known about which risk factors are most important for consumers of all three substances. This study examined the extent to which various factors are associated with dependence on alcohol, cannabis, and/or nicotine in users of all three substances. Methods: 516 Canadian adults with past month use of alcohol, cannabis, and nicotine completed online surveys querying their demographics, personality, substance use history, and levels substance dependence. Hierarchical linear regressions were used to determine which factors best predicted levels of dependence on each substance. Results: Alcohol dependence was associated with levels of cannabis and nicotine dependence, and impulsivity, with 44.9% of variance explained. Cannabis dependence was predicted by alcohol and nicotine dependence levels, impulsivity, and the age of onset of cannabis use, with 47.6% of variance explained. Nicotine dependence was best predicted by alcohol and cannabis dependence levels, impulsivity, and dual use of cigarettes and e-cigarettes, with 19.9% of variance explained. Conclusions: Alcohol dependence, cannabis dependence, and impulsivity were the strongest predictors for dependence on each of the substances. A strong relationship between alcohol and cannabis dependence was evident, warranting further research.

The impacts of caffeine administration, expectancies, and related stimuli on coffee craving, withdrawal, and self-administration.

BACKGROUND: Caffeine is the most commonly consumed psychoactive substance, yet its potential reinforcing properties have been understudied. AIMS: This study examined the impact of caffeine administration and expectancy on coffee-related craving, withdrawal, and cue reactivity via a balanced-placebo design. METHODS: Following 18-h caffeine abstinence, 65 daily coffee consumers (54% male) received either caffeine-containing (100 mg) or placebo gum, along with either accurate or inaccurate information regarding the gum's caffeine content. Participants were exposed to neutral and coffee-related stimuli using different sensory modalities (visual and combined auditory/olfactory). Craving, withdrawal, and heart rate were assessed at baseline and after each cue presentation. Following the cue-reactivity assessments, participants were provided with an opportunity to self-administer units of coffee. RESULTS: Caffeine expectancy was associated with reduced subjective withdrawal 30 min following the gum administration but was not significantly impacted by actual caffeine administration. The presentation of coffee-related cues was found to increase self-reported craving and heart rate, regardless of the expectation that caffeine had been administered. Visual, but not auditory/olfactory, cue reactivity appeared blunted when participants received a prior dose of caffeine. Prior caffeine ingestion also reduced the probability of subsequent coffee self-administration. CONCLUSION: To our knowledge, this is the first examination of the impact of caffeine administration and expectancy on cue-elicited coffee craving and coffee consumption. Although there was some evidence that caffeine expectancy and administration were found to impact subjective withdrawal and self-administration respectively, neither was found to exert strong consistent effects on cue reactivity.