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Purpose: The use of a peripheral nerve stimulator to assess the level of neuromuscular blockade tasks the anesthesia clinician with subjectively assessing the response to neurostimulation. In contrast, objective neuromuscular monitors provide quantitative information. The purpose of this study was to compare subjective evaluations from a peripheral nerve stimulator with objective measurements of neurostimulation responses from a quantitative monitor. Methods: Patients were enrolled preoperatively, and intraoperative neuromuscular blockade management was at the discretion of the anesthesiologist. Electromyography electrodes were placed over the dominant or nondominant arm in a randomized fashion. Following onset of nondepolarizing neuromuscular blockade, the ulnar nerve was stimulated, the response was measured with electromyography, and anesthesia clinicians, who were blinded to the objective measurements, subjectively (visually) evaluated the response to neurostimulation. Results: Fifty patients were enrolled and 666 neurostimulations were performed at 333 different time points. Anesthesia clinicians subjectively overestimated the response of the adductor pollicis muscle following neurostimulation of the ulnar nerve 155/333 (47%) of the time when compared with objective electromyographic measurements. When subjective evaluations and objective measurements differed to any degree, subjective evaluations were higher than objective measurements 155/166 (92%) of the time (95% CI, 87 to 95; P< 0.001), representing significant evidence that subjective evaluation overestimates the response to train-of-four stimulation. Conclusions: Subjective observations of a “twitch” do not consistently correspond to objective measurements of neuromuscular blockade with electromyography. Subjective evaluation overestimates the response to neurostimulation and may be unreliable for determining the depth of block or confirming adequate recovery.

Contexte: La paralysie diaphragmatique unilatérale (PDU) peut potentiellement aggraver les troubles respiratoires du sommeil (TRS). La PDU est associée aux blocs du plexus brachial proximal, tel que les blocs interscalénique et supraclaviculaire. L’impact de la PDU chez les patients atteints de TRS n’est pas connu dans ce contexte. Les objectifs de cette revue exploratoire étaient d’explorer les associations entre la PDU et l’aggravation de la sévérité des TRS, l’oxygénation, et la fonction pulmonaire. Méthode: Une recherche systématique a été mise au point, évaluée par des pairs et appliquée aux bases de données Embase, Medline, CINAHL et Cochrane afin d’inclure les études portant sur des patients adultes (≥ 18 ans) atteints de TRS, où les effets d’une PDU sur la sévérité des TRS, sur l’oxygénation et la fonction pulmonaire étaient examinés. Résultats: Six études (n= 100 patients) portant sur la PDU et les TRS ont été incluses. La population étudiée provenait exclusivement de cliniques de respirologie-sommeil, et ne comptait aucun patient chirurgical. Comparativement au groupe témoin (aucune PDU), la PDU a été associée à un index accru de troubles respiratoires, lesquels étaient les plus prononcés pendant le sommeil paradoxal et en position de décubitus dorsal. Le sommeil en décubitus dorsal et le sommeil paradoxal ont été associés à des événements obstructifs et mixtes (obstructifs et centraux), respectivement. Comparativement au groupe témoin, la PDU a été associée à une saturation en oxygène et à une tension artérielle d’oxygène moyennes et minimales inférieures pendant tous les stades de sommeil et dans toutes les positions. Chez la majorité des patients atteints de PDU, des réductions cliniquement significatives des valeurs du volume expiratoire forcé moyen en une seconde et de la capacité vitale forcée ont été observées, des données compatibles avec une physiologie respiratoire restrictive. Conclusion: Nous avons observé une association entre la paralysie diaphragmatique unilatérale et une sévérité augmentée des troubles respiratoires du sommeil, particulièrement pendant le sommeil paradoxal et en décubitus dorsal. Malgré l’identification de faiblesses dans la conception des études et d’un manque de données périopératoires, les anesthésiologistes devraient garder à l’esprit cette association lorsqu’ils envisagent un bloc du plexus brachial proximal chez les patients souffrant de TRS.

Total knee arthroplasty (TKA) is associated with moderate-to-severe postoperative pain despite the use of femoral nerve block (FNB). The analgesic benefits of adding sciatic nerve block (SNB) to FNB following TKA are unclear. The aim of this meta-analysis was to quantify the analgesic effects of adding SNB to FNB following TKA. We searched the US National Library of Medicine (MEDLINE), Excerpta Medica (Embase), and Cochrane Central Controlled Trials Register databases in March 2015 for randomized and quasi-randomized controlled trials (RCTs) that evaluated the analgesic advantages of adding SNB to FNB compared to FNB alone after TKA. The designated primary outcome was intravenous morphine consumption during the 24-hr postoperative interval. The severity of pain was evaluated at rest and with movement two, four, eight, 12, 24, 36, and 48 hr postoperatively. Morphine consumption during the postoperative 24-48 hr interval, time to first analgesic request, opioid-related side effects, block-related complications, patient satisfaction, functional recovery, and time to hospital discharge were also evaluated. Trials were stratified based on whether a single-shot SNB (SSNB) or continuous SNB (CSNB) was used. Data were combined using random effects modelling. Eight RCTs, including 379 patients, were analyzed. Five trials examined SSNB, and three assessed CSNB. Together, SSNB and CSNB reduced the 0-24 hr weighted mean difference [95% confidence interval] of morphine consumption by 10.6 [−20.9 to −0.3] mg (P= 0.042; I2= 97%) and 20.5 [−28.6 to −12.4] mg (P< 0.001, I2= 86%), respectively. SSNB reduced pain at rest and during movement up to 8 hr postoperatively (P= 0.023 and P< 0.001, respectively), whereas CSNB reduced pain at rest up to 36 hr (P= 0.004) and pain with movement up to 48 hr (P= 0.031). CSNB also decreased the odds of postoperative nausea and vomiting by 91% (P= 0.011). The available evidence supporting the analgesic benefits of adding SNB to FNB following TKA is marked by significant heterogeneity. With this challenge in mind, our meta-analysis suggests that SNB can significantly reduce postoperative opioid consumption and diminish knee pain following TKA compared to no SNB in the setting of FNB. L’arthroplastie totale du genou (ATG) est associée à une douleur postopératoire modérée à grave malgré le recours au bloc du nerf fémoral (BNF). Les avantages analgésiques de l’ajout d’un bloc du nerf sciatique (BNS) au FNB après une ATG sont mal connus. L’objectif de cette méta-analyse était de quantifier les effets analgésiques de l’ajout d’un BNS au BNF après une ATG. Nous avons lancé une recherche dans les bases de données de la Bibliothèque nationale de médecine américaine (MEDLINE), Excerpta Medica (Embase), et du Registre central des études contrôlées Cochrane en mars 2015 pour en tirer les études randomisées et quasi-randomisées contrôlées (ERC) évaluant les avantages analgésiques de l’ajout d’un BNS au BNF par rapport à un BNF seul après une ATG. Le critère d’évaluation principal désigné était la consommation de morphine intraveineuse pendant un intervalle postopératoire de 24 h. La gravité de la douleur a été évaluée au repos et en mouvement à deux, quatre, huit, 12, 24, 36 et 48 h postopératoires. La consommation de morphine pendant l’intervalle postopératoire de 24-48 h, le temps jusqu’à la première demande d’analgésique, les effets secondaires liés aux opioïdes, les complications liées au bloc, la satisfaction des patients, la récupération fonctionnelle et le temps jusqu’au congé de l’hôpital ont également été évalués. Les études ont été stratifiées selon leur recours à une injection unique pour le BNS (BNS-U) ou à une perfusion continue (BNS-C). Les données ont été combinées à l’aide d’un modèle à effets aléatoires. Huit ERC, incluant 379 patients, ont été analysées. Cinq études examinaient le BNS-U, et trois évaluaient le BNS-C. Ensemble, le BNS-U et le BNS-C ont réduit la différence moyenne pondérée pour la période 0-24 h [intervalle de confiance 95 %] de consommation de morphine de 10,6 [−20,9 à −0,3] mg (P= 0,042; I2= 97 %) et de 20,5 [−28,6 à −12,4] mg (P< 0,001, I2 = 86 %), respectivement. Le BNS-U a réduit la douleur au repos et en mouvement jusqu’à 8 h après l’opération (P= 0,023 et P< 0,001, respectivement), alors que le BNS-C a réduit la douleur au repos jusqu’à 36 h (P= 0,004) et la douleur en mouvement jusqu’à 48 h (P= 0,031). Le BNS-C a également réduit le risque de nausées et vomissements postopératoires de 91 % (P= 0,011). Les données probantes à disposition appuyant les avantages analgésiques de l’ajout d’un BNS au BNF après une ATG sont sujettes à une importante hétérogénéité. Tout en gardant cette difficulté à l’esprit, notre méta-analyse laisse à penser que le BNS pourrait réduire de façon significative la consommation postopératoire d’opioïdes et diminuer la douleur au genou après une ATG par rapport à l’absence de BNS dans le cadre d’un BNF.

Purpose: This randomized trial aimed to evaluate the effects of adding continuous epidural analgesia with a bupivacaine and hydromorphone solution to systemic multimodal analgesia following one- or two-level lumbar spinal fusion. Methods: Thirty-nine patients undergoing lumbar spinal fusion, stratified for sex and one- or two-level fusion, were randomized to receive a continuous postoperative epidural infusion of either 0.1% bupivacaine with 15 μg·mL−1hydromorphone (LA group) or 0.9% saline (NS group) at 6 mL·hr−1for 48 hr through an epidural catheter placed intraoperatively. All patients received a standardized postoperative multimodal analgesia regimen. Patients, healthcare providers, and research staff were blinded. The primary outcome measure was cumulative opioid consumption (oral morphine equivalent) during the first 48 hr postoperatively. Results: The mean (SD) cumulative opioid consumption 48 hours postoperatively was 249.3 (143.3) mg in the NS group and 184.7 (208.1) mg in the LA group (mean difference 64.6 mg; 95% confidence interval −54.3 to 183.5; P= 0.27). There were no adverse events in either group. Conclusion: Continuous epidural infusion combined with systemic multimodal analgesia resulted in a mean reduction in 48-hr cumulative opioid consumption of 64.6 mg (95% confidence interval −54.3 to 183.5) following one- or two-level lumbar spinal fusion. This estimate of effect is imprecise, and the routine use of continuous epidural analgesia in this surgical population is not yet warranted. This trial was registered at www.clinicaltrials.gov: NCT00644111.

The economics of the use of an anesthetic drug or device that produces benefit through reduction in operating room (OR) time depends on the day of the week and the total hours of surgical cases in the OR in which they are performed. Principally, this has to do with different durations of the regularly scheduled workday in the ORs within and among hospitals. We tested hypotheses relevant to the economic benefit of avoiding prolonged tracheal extubation times. Observational data were obtained from a multiple-specialty academic tertiary hospital that uses an anesthesia information management system. Prolonged tracheal extubation times were considered those with tracheal extubations occurring 15 min or more after the end of surgery. The assessment of prolonged tracheal extubation times was limited to cases for which the patient’s trachea was intubated and extubated while physically in the OR. Percentages were calculated for each of n= 39 four-week periods. Results are reported as mean (standard error of the mean) of these percentages, and the phrases“at most/least” are used to refer to the corresponding 95% confidence limits. At most, 6.1% [mean 5.5 (0.3)%] of the prolonged tracheal extubation times were attributable to cases that did not end during regular workdays from 7:00 AM-10:59 PM. At least 55.6% of prolonged tracheal extubation times occurred during cases on regular workdays and in an OR with more than eight hours of cases and turnovers [mean 57.0 (0.9)%; P< 0.0001]. This percentage was 23.8 (0.8)% larger than for all other cases. In the absence of an accurate facility-specific cost analysis, prolonged tracheal extubation times should not be treated as fixed costs but as resulting in proportionally increased OR variable costs. En anesthésie, les économies résultant de l’utilisation d’un médicament ou d’un dispositif qui entraîne des avantages en réduisant le temps en salle d’opération (SO) dépendent du jour de la semaine et du nombre total d’heures de cas chirurgicaux réalisés dans cette salle. Ces économies ont surtout à voir avec les différences de durée d’une journée de travail normale planifiée dans les SO à l’intérieur de chaque hôpital et entre les hôpitaux. Nous avons testé des hypothèses pertinentes aux avantages économiques liés à la prévention d’un délai d’extubation trachéale prolongés. Nous avons obtenu des données observationnelles d’un hôpital tertiaire, universitaire et pluri-spécialisé qui se sert d’un système de gestion de l’information en anesthésie. Nous avons défini qu’il y avait délai d’extubation trachéale lorsqu’il se passait 15 min ou plus entre la fin de la chirurgie et l’extubation. Nous nous sommes limités aux cas pour lesquels la trachée du patient a été intubée et extubée alors qu’il était physiquement en SO. Des pourcentages ont été calculés pour chacune de n= 39 périodes de quatre semaines. Les résultats sont rapportés comme moyenne ± écart type de la moyenne de ces pourcentages, et les expressions « au plus / au moins » sont utilisées pour décrire les limites de confiance de 95 % correspondantes. Au plus, 6,1 % des délais d’extubation étaient attribuables à des cas qui ne se sont pas terminés pendant les journées de travail normales, soit de 7 h à 22 h 59 (5,5 % ± 0,3 %). Au moins 55,6 % des délais d’extubation sont survenus pendant des cas lors des journées de travail normales et dans une SO avec plus de huit heures de cas et de roulements (57,0 % ± 0,9 %, P< 0,0001). Ce pourcentage était de 23,8 % ± 0,8 % plus élevé que pour tous les autres cas. En l’absence d’une analyse des coûts précise spécifique à l’institution, les délais d’extubation trachéale ne devraient pas être traités comme des coûts fixes mais comme résultant en des coûts variables de SO augmentant proportionnellement.

Purpose: Criticallyill patients who receive nondepolarizing neuromuscular blocking drugs (NMBDs) may be at risk of developing profound muscle weakness that may last for months after the NMBD is discontinued, especially when large cumulative doses of NMBDs and corticosteroids are coadministered to septic, mechanically ventilated patients. This review focuses on the etiology and clinical features of critical illness myopathy (CIM), summarizes specific risk factors for its development, and discusses strategies that might be used to attenuate or even prevent the development of this potentially devastating syndrome. Clinical features: The etiology of CIM is unknown. Whether it can develop in atrisk patients who undergo lengthy operations during which they receive NMBDs is also unknown. In some patients following exposure to NMBDs their motor systems are impaired secondary to loss of thick (myosin) filaments that render the muscle unexcitable to direct electrical stimulation, while the sensory system is spared. Management of patients who develop NMBD myopathy is supportive, consisting of nutritional support, physical therapy, and daily trials of decreased ventilatory support. Conclusion: Recent guidelines recommend that NMBDs be used in critically ill patients only when absolutely necessary, that the depth of muscle paralysis be monitored to avoid overdosing and metabolite accumulation, and that drug administration be curtailed periodically to allow interruption of sustained NMBD effect.

Purpose: Peripheral opioid receptors may result in antinociceptive effects when occupied by opioids. This study examined intradermally injected sufentanil (S), a highly lipid soluble opioid, administered with and without lidocaine (L), in a thermal pain model. Methods: Nine volunteers were instructed on the method of magnitude estimation of pain before undergoing baseline testing with seven seconds thermal stimuli between 44 and 52°C, delivered by a contact thermal stimulator at five cutaneous forearm sites. Then, four sites randomly received injections of equal volumes (0.1 mL) of either normal saline (NS), lidocaine 0.5% (L), sufentanil 0.75 μg (S), lidocaine 0.5% plus sufentanil 0.75 μg (L + S), and one site was not injected and served as reference (REF). Testing was repeated at six, 30, 60, 90, 120, and 150 min following injection. The pain elicited by each stimulus was normalized to the subjects response to the 50°C stimulus at the REF site. Results: Baseline testing showed small (P= ns) differences in pain scores. At six minutes, the lidocaine sites (L, L + S) had pain scores that were mean 83% (range 78–88%) lower than the other sites (P&lt; 0.05), but there was no difference between the L and L + S sites or between the S and NS or REF sites. At 30 and 60 min these pain scores were mean 38% (29–44%) and 20% (8–30%) less than at the REF NS, and S sites (P= ns). At 90 min and later times, the pain scores had returned to baseline. Conclusions: These results suggest that intradermal sufentanil alone has no analgesic effect. Further, in combination with lidocaine, sufentanil does neither potentiate nor prolong the analgesic effect of lidocaine.

Purpose: This two-part review summarizes the current knowledge of physiological mechanisms, pharmacological modalities and controversial issues surrounding preemptive analgesia. Source: Articles from 1966 to present were obtained from the MEDLINE databases. Search terms included: analgesia, preemptive; neurotransmitters; pain, postoperative; hyperalgesia; sensitization, central nervous system; pathways, nociception; anesthetic techniques; analgesics, agents. Principal findings: The physiological basis of preemptive analgesia is complex and involves modification of the pain pathways. The pharmacological modalities available may modify the physiological responses at various levels. Effective preemptive analgesic techniques require multi-modal interception of nociceptive input, increasing threshold for nociception, and blocking or decreasing nociceptor receptor activation. Although the literature is controversial regarding the effectiveness of preemptive analgesia, some general recommendations can be helpful in guiding clinical care. Regional anesthesia induced prior to surgical trauma and continued well into the postoperative period is effective in attenuating peripheral and central sensitization. Pharmacologic agents such as NSAIDs (non-steroidal anti-inflammatory drugs) opioids, and NMDA (N-methyl-D-aspartate)- and alpha-2-receptor antagonists, especially when used in combination, act synergistically to decrease postoperative pain. Conclusion: The variable patient characteristics and timing of preemptive analgesia in relation to surgical noxious input requires individualization of the technique(s) chosen. Multi-modal analgesic techniques appear most effective.

Purpose: To examine the current role of anesthesiologists in Canadian undergraduate medical education (UME).

A correction to this paper has been published: https://doi.org/10.1007/s12630-021-01981-9

The effects on gastric pH of the H2-receptor antagonist ranitidine (R) with 0.3 molar (M) sodium citrate (SC) as an oral effervescent and those of plain SC were studied in 25 patients scheduled for elective surgery. Following induction of general anaesthesia, the gastric contents were evacuated via a nasogastric tube, and a pH electrode was placed in the stomach. Then, eight patients received R 300 mg plus SC dose (Group R300), ten received R 150 mg plus SC dose (Group R150), and seven received 50 ml SC alone (Group SC). The drugs were administered orally in a double-blind fashion, and the gastric pH was recorded continuously over a period of 24 hr. Mean (range) baseline pH values were 1.2 (0.8–1.8), 1.3 (1.0–1.8), and 1.2 (0.9–1.6) in the R300, R150, and SC groups, respectively (P = NS among groups). These values increased to 7.0 (6.2–7.5), 6.9 (6.3–7.3), and 4.9 (1.9–7.3), respectively, at emergence from anaesthesia (P < 0.05 for R300 vs SC and R150 vs SC). Two minutes after administration of R300 and R150, a mean (range) gastric pH of 6.8 (5.8–7.5), and 5.6 (1.2–7.0), respectively, was reached, and remained above 2.5 for 14 hr (P = NS). Plain SC increased the gastric pH within two minutes to a mean of 6.8 (6.7–7.0), and maintained it above 2.5 for six hours (P < 0.05 for R300 vs SC at 8, 10, 12, and 14 hr after induction). We conclude that both the combination of R plus SC, and SC alone are rapidly effective in neutralizing gastric acid when administered orally after induction of anaesthesia. However, the effectiveness of plain SC is shorter-lived, and if maintenance of gastric pH above 2.5 for longer than six hours is needed, the R plus SC combination should be administered.

We compared fade measurements in response to double-burst stimulation (DBS) at 10 mA above the threshold for the second response (D2) to that for DBS at 60 mA in order to determine the utility of low-current DBS testing. In 20 healthy adults undergoing general endotracheal anaesthesia with isoflurane 0.5– 1% end-tidal, a vecuronium infusion (0.25–1.5 μg · kg−1· min−1) was delivered until a stable train-of-four (TOF) response to ulnar nerve stimulation was documented with an adductor pollicis force transducer. Then DBS responses were recorded, and the D2/D1ratios were determined at 60 mA and at 10 mA above the D2threshold current (TS + 10 mA). The mean difference (bias) between D2/D1 @TS+10 mAand D2/D1 @ 60 mAwas −0.02 (P < 0.05); the 95% limits of agreement were from −0.12 to +0.08. The bias and limits of agreement were similar to those for T4/T1of train-of-four. A strong correlation was noted between the degrees of fade determined at the low and high currents (r = 0.95). We conclude that, although stimulation at 10 mA above the D2threshold is associated with a slight negative bias, it is virtually inter-changeable with testing at higher current in the clinical setting. This technique thus may be used effectively to monitor neuromuscular fade in settings where neurostimulation with low current is deemed desirable.