Impact of chronic treatment by ß1-adrenergic antagonists on Nociceptive-Level (NOL) index variation after a standardized noxious stimulus under general anesthesia: a cohort study.

During the perioperative period, nociception control is certainly one of the anesthesiologist's main objectives when assuming care of a patient. There exists some literature demonstrating that the nociceptive stimuli experienced during surgery are responsible for peripheral and central sensitization phenomena, which can in turn lead to persistent postsurgical pain. An individualized approach to the evaluation and treatment of perioperative nociception is beneficial in order to avoid the sensitization phenomena that leads to prolonged postoperative pain and to minimize the consumption of opiates and their adverse effects. In terms of sensitivity, specificity, and positive/negative predictive values when compared to heart rate (HR) and mean arterial pressure (MAP), recent literature has shown that the NOL variation (ΔNOL) is the best index to distinguish noxious from non-noxious stimuli. Chronic treatment with ß1-adrenergic antagonists may constitute a limitation to the use of the NOL index. ß1-adrenergic antagonists induce a depressive action on the heart rate, which results in a limitation of its variability after a noxious stimulus. Since heart rate and heart rate variability are two parameters integrated into the NOL index, the validity of the NOL index in a population of patients receiving ß1-adrenergic antagonists has not yet been determined. Our study sought to explore the NOL index, the BIS, and the heart rate variation in a group of patients under chronic treatment with ß1-adrenergic antagonists submitted to standardized noxious stimulus under general anesthesia. We then compared those results to a control group of patients from our previous study (CJA group) that received no ß1-adrenergic antagonist chronic treatment. The patients in this study were subjected to a standardized anesthetic protocol from induction up to 3 min after a standardized tetanic stimulus to the ulnar nerve at a frequency of 100 Hz and an amperage of 70 mA, for a duration of 30 s. Data were electronically recorded to obtain NOL, BIS, and heart rate values every 5 s for the duration of the protocol. The NOL maximal mean value reached after noxious stimulation was not different between our two cohorts (CJA: 30(14) versus BETANOL: 36(14) (p = 0.12)). There was no statistically significant difference between our cohorts in regards of the NOL AUC representing the variation of the NOL over a 180 s period (CJA: 595(356) versus BETANOL: 634(301) (p = 0.30)). However, a repeated measurement ANCOVA identified slight statistically significant differences between our cohorts in the peak of variation of the NOL index between 20 and 65 s after noxious stimulation, the NOL index of the cohort of beta-blocked patients being higher than the CJA patients. Moreover, the time to reach the maximum value was not different (CJA: 73(37) versus BETANOL: 63(41) (p = 0.35)). NOL sensitivity and specificity to detect a noxious stimulus under general anesthesia were similar in patients taking beta-blockers or not, and were better than those of heart rate and Bispectral index (AUC NOL 0.97, CI(0.92-1), versus AUC BIS 0.78, CI(0.64-0.89) and AUC HR 0.66, CI(0.5-0.8)). In conclusion, the NOL index is a reliable monitor to assess nociception in a population of patients under chronic beta-blocker therapy. Patients under such therapy achieve similar maximal NOL values over a 180 s period after a standardized noxious stimulus and the NOL variation over time, represented by the AUC is not significantly different from a cohort of non-beta-blocked patients. Whether the patient takes beta-blockers or not, sensitivity of the NOL index is greater than that seen for BIS index or heart rate to detect an experimental noxious stimulus under general anesthesia.

Ultrasound evaluation of inferior vena cava compression in tilted and supine term parturients.

PURPOSE: Hypotension is common following spinal anesthesia (SA) during elective Cesarean delivery (CD). Although common practice is to alleviate inferior vena cava (IVC) compression, limited evidence supports a 15° tilt for CD. We measured collapsibility of the IVC in supine and 15° left lateral tilt positions with ultrasound before and after SA and phenylephrine infusion in term parturients. METHODS: Twenty term parturients scheduled for CD were recruited for this prospective study. Ultrasound measurements of the IVC were taken 1) supine before SA, 2) tilted 15° before SA, 3) supine after SA, and 4) tilted 15° after SA. A phenylephrine infusion was begun after injection of SA. The primary outcome was to evaluate the impact of position on the IVC collapsibility index (IVCCI): a measure of the difference between the maximum and minimum IVC diameter with respiration. RESULTS: The mean (standard deviation) IVCCI (%) before SA was higher in the supine 19.5 (8.0) than in the tilted 15.0 (6.4) position (mean difference, 4.5; 95% confidence interval [CI], 0.1 to 8.9; P = 0.04). After SA, there was no significant difference between IVCCI (%) in the supine 17.8 (8.3) and tilted 14.2 (6.9) position (mean difference, 3.5; 95% CI, -0.9 to 7.9; P = 0.13). There was no correlation between the pre-spinal IVVCI measurements and the quantity of phenylephrine used during the surgery. CONCLUSION: The IVCCI was lower in the 15° tilt position than in the supine position, but not after SA with a phenylephrine infusion. Ultrasound imaging can help identify IVC compression. TRIAL REGISTRATION: www.clinicaltrials.gov (NCT03410199); registered 18 January 2018.

RéSUMé: OBJECTIF: L'hypotension est fréquente après une rachianesthésie pendant un accouchement par césarienne programmée (CP). Bien que la pratique courante consiste à atténuer la compression de la veine cave inférieure (VCI), des données probantes limitées encouragent une latéralisation de 15 ° durant la CP. Avec l'échographie, nous avons mesuré la collapsibilité de la VCI en décubitus dorsal et en position d'inclinaison latérale gauche de 15° avant et après la rachianesthésie et la perfusion de phényléphrine chez des parturientes à terme. MéTHODE: Vingt parturientes à terme devant subir une CP ont été recrutées dans le cadre de cette étude prospective. Les mesures échographiques de la VCI ont été prises 1) en décubitus dorsal avant la rachianesthésie, 2) avec une latéralisation de 15° avant la rachianesthésie, 3) en décubitus dorsal après la rachianesthésie, et 4) avec une latéralisation de 15° après la rachianesthésie. Une perfusion de phényléphrine a été amorcée après l'injection de la rachianesthésie. Le critère d'évaluation principal était l'impact de la position sur l'indice de collapsibilité de la VCI (ICVCI), soit une mesure de la différence entre les diamètres maximal et minimal de la VCI avec respiration. RéSULTATS: Le ICVCI moyen (écart type) (%) avant la rachianesthésie était plus élevé en décubitus dorsal, à 19,5 (8,0), qu'en position latéralisée, à 15,0 (6,4) (différence moyenne, 4,5; intervalle de confiance [IC] 95 %, 0,1 à 8,9; P = 0,04). Après la rachianesthésie, aucune différence significative n'a été observée entre l'ICVCI (%) en décubitus dorsal, à 17,8 (8,3), et en position latéralisée, à 14,2 (6,9) (différence moyenne, 3,5; IC 95 %, -0,9 à 7,9; P = 0,13). Il n'y avait aucune corrélation entre les mesures de l'ICVCI pré-rachianesthésie et la quantité de phényléphrine utilisée pendant la chirurgie. CONCLUSION: L'ICVCI était plus bas en position latéralisée à 15 ° qu'en décubitus dorsal, mais pas après une rachianesthésie avec une perfusion de phényléphrine. L'échographie peut aider à identifier la compression de la VCI. ENREGISTREMENT DE L'éTUDE: www.clinicaltrials.gov (NCT03410199); enregistrée le 18 janvier 2018.

A randomized controlled trial comparing nociception level (NOL) index, blood pressure, and heart rate responses to direct laryngoscopy versus videolaryngoscopy for intubation: the NOLint project.

PURPOSE: The effect of direct laryngoscopy using a Macintosh blade (MAC) vs GlideScope™ videolaryngoscopy using a Spectrum LoPro blade (GVL) on nociceptive stimulation has not been quantitatively studied. This study used the new nociception level (NOL) index to compare the nociceptive response induced by GVL or MAC during laryngoscopy with or without intubation. METHODS: Patients underwent two laryngoscopies at four-minute intervals (L1, L2), one with GVL and the other with MAC (first randomization). A third laryngoscopy (L3) followed by tracheal intubation was performed four minutes after L2 (GVL or MAC, second randomization). Nociception was quantitatively assessed by NOL and standard hemodynamic parameters (heart rate [HR] and mean arterial pressure). For the crossover design, blade comparisons accounted for sequence and blade type. A possible carryover effect between laryngoscopies was assessed. RESULTS: In the 50 patients randomized, there was no carryover effect from one laryngoscopy to the next for all analyzed parameters. Nociception level index peak values were higher with MAC than GVL. Analysis of ΔNOL showed a lower nociceptive response with GVL for L1+L2 combined. Mean peak NOL values were significantly higher after L3+intubation than after L1+L2, for both GVL and MAC groups. Analysis of ΔHR values did not show a significant difference between GVL and MAC for any laryngoscopy. CONCLUSION: Laryngoscopy alone with GVL induces less nociception than with MAC. The NOL was more sensitive than HR at detecting nociceptive responses to MAC vs GVL. Additionally, and irrespective of which technique/blade was used, the combination of laryngoscopy + tracheal intubation produced a much greater nociceptive response than the laryngoscopy alone. TRIAL REGISTRATION: www.clinicaltrials.gov (NCT03277872); registered 29 August 2017.

RéSUMé: OBJECTIF: L'effet de la laryngoscopie directe avec une lame Macintosh (MAC) par rapport à la vidéolaryngoscopie à l'aide d'un GlideScope™ avec lame Spectrum LoPro (GVL) sur la stimulation nociceptive n'a pas été quantitativement étudié. Cette étude a utilisé le nouvel indice de niveau de nociception (NOL) pour comparer la réponse nociceptive induite par une laryngoscopie avec GVL ou MAC avec ou sans intubation. MéTHODE: Les patients ont subi deux laryngoscopies à des intervalles de quatre minutes (L1, L2), l'une par GVL et l'autre par MAC (première randomisation). Une troisième laryngoscopie (L3) suivie d'une intubation trachéale a été effectuée quatre minutes après L2 (GVL ou MAC, deuxième randomisation). La nociception a été quantitativement évaluée à l'aide de l'indice NOL, et les paramètres hémodynamiques standard (fréquence cardiaque [FC] et pression artérielle moyenne) ont été mesurés. Dans le volet croisé de l'étude, les comparaisons de lames ont tenu compte de la séquence et du type de lame. La possibilité d'un effet de persistance entre les laryngoscopies a été évaluée. RéSULTATS: Chez les 50 patients randomisés, il n'y a eu aucun effet de persistance d'une laryngoscopie à la suivante pour tous les paramètres analysés. Les valeurs maximales de l'indice de nociception étaient plus élevées avec les lames MAC qu'avec la vidéolaryngoscopie GVL. L'analyse de ΔNOL a montré une réponse nociceptive inférieure avec la vidéolaryngoscopie GVL pour L1+L2 combinés. Les valeurs maximales moyennes de NOL étaient significativement plus élevées après L3+intubation qu'après L1+L2, tant pour les groupes GVL que MAC. L'analyse des valeurs ΔFC n'a pas montré de différence significative entre les techniques GVL et MAC pour quelque laryngoscopie que ce soit. CONCLUSION: La laryngoscopie seule avec le GlideScope induit moins de nociception qu'avec une lame MAC. L'indice NOL était plus sensible que les FC pour détecter les réponses nociceptives à la laryngoscopie MAC vs GVL. En outre, et indépendamment de la technique/lame utilisée, la combinaison de laryngoscopie + intubation trachéale a produit une réponse nociceptive beaucoup plus importante que la laryngoscopie seule. ENREGISTREMENT DE L'éTUDE: www.clinicaltrials.gov (NCT03277872); enregistrée le 29 août 2017.

Assessing the antinociceptive effect of nitrous oxide to tetanic stimulation in anaesthetised patients with new intra-operative nociception monitors: An observational study.

BACKGROUND: Nitrous oxide (N2O) has been used since the 19th century for its analgesic, antinociceptive and anxiolytic effects during surgical procedures in awake and anaesthetised patients. However, quantification of noxious stimuli that occur under general anaesthesia is a constant challenge for anaesthesiologists, and recently two new indices have been developed to assess intra-operative nociception. OBJECTIVE: The aim of this study was to quantify with new indices as well as with more classical clinical parameters the antinociceptive effect of N2O during general anaesthesia. DESIGN: Prospective, open label, patient-blinded, observational and descriptive trial. SETTING: Single-centre academic hospital. PARTICIPANTS: Forty American Society of Anesthesiologists' physical status 1 to 3 patients undergoing general anaesthesia for elective abdominal surgery via laparotomy were recruited. MAIN OUTCOMES MEASURES: Intra-operative pain was assessed using a standardised electrical stimulation of the forearm (tetanic stimulation at 70 mA, 100 Hz for 30 s), at 0, 25 and 50% inhaled N2O/O2. Heart rate (HR), mean arterial blood pressure, bispectral index, the analgesia nociception index and the nociception level (NOL) index were used to evaluate intra-operative nociception before and after each standardised tetanic stimulation. RESULTS: There was a 16% reduction of the analgesia nociception index reaction, a 31% reduction of the NOL reaction and a 51% reduction of the HR reaction to a standardised electrical tetanic nociceptive stimulation during administration of 50% N2O. Administration of 50 or 25% inhaled N2O produced the same quality of antinociception based on HR and NOL index analyses. HR and the NOL index were the best parameters to identify the antinociceptive effect of intra-operatively administered N2O. CONCLUSION: In anaesthetised patients, our study demonstrated clinically significant antinociceptive properties of N2O. Our results showed that low concentrations of N2O (25%) are as effective as higher concentrations (50%) to achieve a significant antinociceptive effect. These findings may help decrease negative effects of using higher concentrations of N2O, including its side effects and its environmental pollution. TRIAL REGISTRATION: ClinicalTrials.gov registration identifier: NCT02701478.

Self-directed learning by video as a means to improve technical skills in surgery residents: a randomized controlled trial.

BACKGROUND: With their demanding schedules, surgical residents have limited time to practice techniques. The aim is to evaluate the pedagogic model of self-directed learning using video in surgery residents. METHODS: Informed consent was obtained from all the participants. A randomized controlled trial was conducted in 2018 at Hôpital Maisonneuve-Rosemont (University of Montreal). Participants were general surgery residents. There were 27 eligible residents; 22 completed the study. They were filmed performing an intestinal anastomosis on cadaveric pig bowel. The self-directed learning by video (SDL-V) group was given an expert video, which demonstrated the technique performed by an experienced surgeon. The control group continued with their regular duties. Three weeks later, participants performed a second filmed anastomosis. Two attending surgeons evaluated the residents' filmed anastomosis using the Objective Structured Assessment of Technical Skills scale. After their second anastomosis, all participants had access to the expert video and completed a survey. RESULTS: Score did not differ significantly between groups during the first (control: 23.6 (4.5) vs. SDL-V: 23.9 (4.5), p = 0.99, presented as mean (SD)) or second filmed anastomosis procedure (control: 27.1 (3.9) vs. SDL-V: 29.6 (3.4) p = 0.28). Both groups improved significantly from pre- to post-intervention (mean difference between the two anastomosis procedure with 95% CI for control: 3.5, [1.1; 5.9] and for SDL-V: 5.8, [3.4: 8.2]). Correlation between the evaluators for score was moderate (r = 0.6, 95% CI: [0.3: 0.8]). The pass/fail global evaluation exhibited poor inter-rater reliability (Kappa: 0.105, 95% CI: [- 0.2:0.4]). On the survey, all participants wanted more expert-made videos of specific surgical techniques. CONCLUSIONS: Despite a higher final OSATS score for the intervention group, self-directed learning by video failed to produce a statistically significant difference on the overall OSATS scores between the two groups in this small cohort.

Dexmedetomidine Versus Remifentanil for Monitored Anesthesia Care During Endobronchial Ultrasound-Guided Transbronchial Needle Aspiration: A Randomized Controlled Trial.

BACKGROUND: We hypothesized that, compared to remifentanil, dexmedetomidine used for endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) performed under monitored anesthesia care (MAC) in nonintubated patients would result in fewer episodes of major respiratory adverse events (number of episodes of bradypnea, apnea or desaturation) but no difference in satisfaction with perioperative conditions. METHODS: Sixty (American Society of Anesthesiologists physical status I-III) patients scheduled to undergo EBUS-TBNA under MAC were randomized to receive either remifentanil (0.5 µg/kg IV bolus) in 10 minutes, followed by 0.05-0.25 µg/kg/min, or dexmedetomidine (0.4 µg/kg IV bolus) in 10 minutes, followed by 0.5-1.0 µg/kg/h. The primary outcome was the number of major respiratory adverse events (bradypnea, apnea, or hypoxia). The secondary outcomes included hemodynamic variables, discharge time from the postanesthesia care unit, endotracheal lidocaine use, patient's sedation using the Observer Assessment of Alertness/Sedation Scale, operative conditions, operator and patient satisfaction, pain, coughing, vocal cord mobility, recall, and nausea/vomiting. RESULTS: Dexmedetomidine produced significantly fewer episodes of major respiratory events (bradypnea, apnea, or desaturation), with 0 [0-0.5] episodes versus 2 [0-5] (median [interquartile range]) (P = .001), than did remifentanil. Fewer episodes of bradypnea or apnea (dexmedetomidine: 0 [0-0] versus remifentanil: 0 [0-0.5]; P = .031), and fewer episodes of desaturation (dexmedetomidine: 0 [0-0.5] versus remifentanil: 1 [0-4]; P = .039) were recorded in the dexmedetomidine group. The time needed for patients to meet postanesthesia care unit discharge criteria (Aldrete score: 9) after EBUS-TBNA was longer in the dexmedetomidine group (10 [3-37.5] minutes) versus the remifentanil group (3 [3-5] minutes) (P < .001). No differences were observed in the 2 groups for sedation depth (Observer Assessment of Alertness/Sedation Scale), endotracheal lidocaine use, operative conditions, operator and patient satisfaction, pain, coughing, vocal cord mobility, recall, and nausea/vomiting episodes. CONCLUSIONS: Dexmedetomidine resulted in fewer respiratory adverse events during EBUS-TBNA under MAC, when compared to remifentanil, with no difference in overall operative conditions. However, dexmedetomidine use was associated with delayed postoperative discharge.

Correlation between incremental remifentanil doses and the Nociception Level (NOL) index response after intraoperative noxious stimuli.

BACKGROUND: The Pain Monitoring Device (PMD) monitor (Medasense Biometrics Ltd., Ramat Gan, Israel) uses the Nociception Level (NOL) index, a multiple parameter-derived index that has recently shown a good sensitivity and specificity to detect noxious stimuli. The aim of this study was to assess the latest version of the device (PMD200TM) on variations of the NOL response after standardized tetanic stimuli to study the correlation between remifentanil doses and NOL. METHODS: Data from 26 patients undergoing midline laparotomy and receiving a desflurane-remifentanil-based anesthetic coupled with low thoracic epidural analgesia were analyzed. A standardized tetanic stimulus was applied to the forearm of the patients at different remifentanil infusion rates. The primary aim was to evaluate the correlation between post-tetanic stimulation NOL values from the PMD200 and remifentanil doses. The NOL index variations after experimental and clinical stimuli were also compared with heart rate (HR), mean arterial pressure (MAP), and Bispectral Index™ (BIS). RESULTS: A correlation between post-tetanic stimulation NOL values and remifentanil doses was found (r = -0.56; 95% confidence interval [CI], -0.70 to -0.44; P < 0.001). The NOL discriminated noxious from non-noxious states with the maximal Youden's index value of the NOL receiver operating characteristic (ROC) curve showing a specificity of 88% (95% CI, 69.0 to 100) and sensitivity of 79.1% (95% CI, 56.2 to 95.5). The area under the NOL ROC curve (AUC, 0.9; 95% CI, 0.84 to 0.95) was significantly different from the other variables (P < 0.001 vs HR; P < 0.001 vs MAP; P < 0.001 vs BIS). CONCLUSIONS: The NOL value after noxious stimulus decreased with incremental remifentanil doses, showing a significant inverse correlation between the NOL index and opioid doses. The sensitivity and specificity of NOL to discriminate between noxious and non-noxious stimuli suggests its interesting potential as a monitor of nociception intensity during anesthesia. TRIAL REGISTRATION: www.clinicaltrials.gov (NCT02884778); 27 July, 2016.

Evaluation of the analgesia nociception index (ANI) in healthy awake volunteers.

BACKGROUND: Analgesia might be evaluated with simple changes in vital signs, a non-specific and non-sensitive method. Heart rate variability (HRV) correlates with autonomous nervous system activity and can be used to evaluate painful stimuli. Heart rate variability is then transformed into a numeric scale called the analgesia nociception index (ANI), where higher values represent predominant parasympathetic tone, thus low nociception. Under general anesthesia, the ANI decreases following painful stimuli and increases after administration of analgesia, but significant interindividual variability is present. The goal of the present study was to evaluate the ANI as a pain index in healthy awake volunteers. METHODS: Following research ethics board approval, participants were positioned supine in a calm operating room. The participants' vital signs and ANI were monitored. After evaluation of all parameters without any stimulation, 23 volunteers received a 2 Hz electrical stimulus at the wrist with increasing current intensity from 0-30 mA (5 mA increments). The current was kept constant for three minutes at each level, and the volunteers rated their pain on a numeric rating scale (NRS) every minute. The Pearson correlation coefficient and linear regression were used to analyze the relationship between the ANI and the NRS score. The ANI absolute values and the variations from baseline were both analyzed. RESULTS: There was a very weak negative correlation between the NRS score and ANImean (Pearson, -0.089; 95% confidence interval [CI], -0.192 to -0.014; P = 0.045) and between the NRS score and ∆ANImean (Pearson, -0.174; 95% CI, -0.272 to -0.072; P < 0.001; regression slope, -0.586; 95% CI, -0.930 to -0.243; P < 0.001). Heart rate, blood pressure, and respiratory rate did not vary significantly throughout the study. CONCLUSIONS: These findings provide little evidence to support use of the ANI in awake subjects or in awake patients such as those in the emergency room or in the intensive care unit. Nevertheless, based on an important difference between the expected correlation and the real correlation between the ANI and the NRS scores found in our results, the present study might be underpowered. Studies with a larger sample size would be required to enable firm conclusions about the clinical utility of the ANI in this population of awake volunteers as well as in awake patients. This study was registered with ClinicalTrials.gov (NCT02589093).

Effect of chemotherapy and heat on biomechanical properties of absorbable sutures.

BACKGROUND: The quality of tissue repairs depends on tissue integrity, surgical technique, and material properties of the sutures used. Currently, there is no clear consensus on which is the best suture to use during cytoreductive surgery combined with hyperthermic intraperitoneal chemotherapy. The aim of this study was to evaluate the impact of heat and chemotherapy on sutures' biomechanical properties. METHODS: Six different 3.0 absorbable sutures (Biosyn, Dexon II, Maxon, Monocryl, PDS II, and Vicryl Plus) were tested. All suture strands were incubated for a 24-h period in saline, mitomycin-c, and oxaliplatin at 37 and 45°C. Suture loops were then loaded to failure using a servohydraulic testing machine. Data for tensile breaking force (TBF) and elongation rate were collected for all samples. RESULTS: Under basal condition, Maxon was the strongest of all sutures with a TBF of 59.6 ± 4.3 N (P < 0.01), and no significant difference in TBF was observed between other sutures. Heat alone had no impact on sutures' biomechanical parameters. Exposition to mitomycin-c at 45°C did not significantly affect sutures' basal tensile properties, with Maxon remaining the strongest suture. When incubated in oxaliplatin at 45°C, the six suture types had a similar TBF. In all experimental conditions, multifilament sutures had a significantly lower elongation rate than monofilament sutures, and no correlations were demonstrated between elongation rate and the TBF of sutures. CONCLUSIONS: This study showed that exposition to heated chemotherapy did not significantly affect absorbable sutures biomechanical properties.

Interference between surgical magnetic drapes and pacemakers: an observational study comparing commercially available devices and a new magnetically isolated drape.

BACKGROUND: Magnetic fields may potentially interfere with the function of cardiovascular implantable electronic devices. Sterile magnetic drapes used to hold surgical instruments are often placed on the patient's thorax, and they are likely to interfere with the function of these devices. METHODS: Thirty patients were recruited to compare a new prototype surgical magnetic drape (LT10G™ by Menodys) made with bottom-isolated ferrite magnets to the Covidien magnetic drape we used in a previous study. Twenty additional patients were recruited to compare the prototype drape with four commercially available surgical magnetic drapes. RESULTS: Magnetic interference was found in 33 of the 50 total patients (70 %) when the Covidien drape was placed over the pacemaker. Of the 20 additional patients, 5 patients (25 %) displayed magnetic interference with a second type of surgical magnetic drape. A third magnetic drape caused interference in one patient (5 %), whereas a larger drape of the same model did not interfere in any patient. No patients demonstrated magnetic interference with the prototype drape. CONCLUSION: Bottom isolation of magnets in the prototype magnetic drape (LT10G™) used during surgery prevents magnetic interference in all patients when placed over the pacemaker. Three of the four commercially available magnetic drapes tested demonstrated magnetic interference. Flipping the prototype drape is not recommended as it may expose non-isolated magnets to the cardiovascular implantable electronic device.

Impact of electrocautery and hyperthermic intraperitoneal chemotherapy on intestinal microvasculature in a murine model.

BACKGROUND: Electrocautery (EC) is used during cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC). Using a murine model, we studied the effect of HIPEC on small bowel EC lesions and surrounding normal tissues. METHODS: Thirty-two rats were divided into five groups: a control group with EC lesions; EC plus intraperitoneal heated 5% dextrose (D5W); EC plus oxaliplatin (OXA, 460 mg/m(2)); EC plus mitomycin C 10 mg/m(2) (MMC10); EC plus MMC 35 mg/m(2) (MMC35). EC lesions and surrounding tissue microvasculature were analysed after intravenous injection of fluorescein. RESULTS: In the ileum OXA significantly reduced EC lesions microvasculature compared with the control group; MMC10 caused greater reduction than the control, D5W and MMC35 groups. Surrounding tissue microvasculature was significantly reduced by MMC35 exposure when compared to the control, OXA or MMC10 groups. In the jejunum EC injuries exposed to OXA or MMC10 had significantly reduced microvasculature compared to the control, heated D5W and MMC35 groups. Surrounding tissue microvasculature was significantly reduced by MMC35 exposure when compared to the OXA group. There was no significant microvasculature difference between the EC lesions made before or after HIPEC. CONCLUSION: HIPEC with OXA and MMC10 potentiates small bowel wall EC injuries. MMC35 reduces surrounding unharmed tissue microvasculature. There was no effect of hyperthermia alone on microvasculature.

Electrocautery effect on intestinal vascularisation in a murine model.

BACKGROUND: The use of electrocautery devices is associated with complications such as perforation or fistulisation when used near intestinal structures. This is likely due to its effect on vascularisation of the bowel wall. To test this hypothesis we established a murine model to quantify the effect of electrocautery injury on the intestinal microvascularisation. METHODS: Sprague-Dawley rats were subjected to five electrocautery injuries on the small bowel in coagulation mode (30 W intensity) and in cut mode (40 W, 80 W and 200 W intensities) for durations of 1, 2 and 5 s. 5 mg/kg of fluorescein was injected intravenously, the injured bowel segments harvested and the rat sacrificed. The segments were analysed to measure the fluorescence of injured bowel compared to adjacent unharmed tissue. RESULTS: A significant decrease in bowel wall microvascularisation occurred with increasing intensity (coag 30 W/cut 40 W versus cut 200 W 1 s: p < 0.05) and duration of electrocautery injury (cut 40 W 1/2 s versus 5 s: p < 0.05). There was a 40% perforation rate when decreased bowel wall microvascularisation was 25% or more. Despite similar electrocautery injury, a significantly greater microvascularisation decrease was observed in jejunum compared to ileum (p < 0.05). CONCLUSION: We successfully established a murine model to quantify the decrease of bowel wall microvascularisation associated with electrocautery use. Unsurprisingly, the decrease in microvascularisation is greater with higher intensity and duration of electrocautery and is associated with more perforations in the experimental model. The jejunum seems more vulnerable to electrocautery injury than the ileum. These observations support caution when using electrocautery devices near intestinal structures.

Performing post-tetanic count during rocuronium blockade has limited impact on subsequent twitch height or train-of-four responses.

BACKGROUND: Waiting five to six minutes before measuring a train-of-four (TOF) after a 50-Hz tetanic stimulation or post-tetanic count (PTC) in order to allow the facilitation of transmission to subside is commonly recommended but is based on limited evidence. The purpose of this study was to measure the TOF responses after PTC in one hand and to compare the responses with those in the contralateral (control) hand. METHODS: Twenty-two adult patients undergoing elective surgery under opioid-desflurane anesthesia were fitted with sensors to measure displacement of their thumbs in response to ulnar nerve stimulation. Rocuronium 0.6 mg·kg(-1) was administered and TOF stimulation was applied to both sides. One side was randomized to PTC (50-Hz tetanus followed by a three-second pause and 15 1-Hz stimuli) when the opposite (control) side recovered to 10% first twitch (T1) height. Train-of-four stimulation was continued bilaterally every 20 sec until 30 min after PTC. Comparisons of the T1 and TOF ratio (T4/T1) were made at two, five, ten, 20, and 30 min. RESULTS: The mean (standard deviation [SD]) T1 value in the PTC arm was 11.8 (7.1)% just before PTC. The T1 values were significantly greater in the PTC arm at two, five, and ten minutes, with mean (SD) differences of 6.3 (6.7)%, 9.4 (6.8)%, and 7.4 (3.9)%, respectively (P = 0.008). There were no significant differences in T1 values between groups at 20 and 30 min, and no statistically significant differences in T4/T1 values at any time. CONCLUSION: A small but clinically insignificant increase in T1 is seen for at least ten minutes after PTC without any detectable change in T4/T1 values. The TOF responses are reliable as early as one minute after PTC.

Modeling the anesthetic effect of ropivacaine after a femoral nerve block in orthopedic patients: a population pharmacokinetic-pharmacodynamic analysis.

BACKGROUND: Even though ropivacaine is frequently used during orthopedic surgery, the relationship between plasma concentrations and degree of sensory anesthesia after a peripheral nerve block is currently unknown. The aim of this study was to characterize this relation using population pharmacokinetic-pharmacodynamic modeling. METHODS: Femoral nerve block was performed by the anterior approach using a single injection (20 ml) of 0.5% ropivacaine hydrochloride in 20 patients scheduled for total knee arthroplasty under spinal anesthesia. Sensory thresholds in response to a gradual increase in transcutaneous electrical stimulation (primary endpoints), loss and recovery of ice-cold sensation, as well as total ropivacaine plasma concentrations were determined up to 4 days after administration of the local anesthetic. Using NONMEM (ICON, USA), sensory block was modeled by assuming an equilibration delay (ke0) between amount in the depot and effect-site compartments. RESULTS: Mean effect-site amount producing 90% of the maximum possible effect (AE90) was estimated as 20.2 mg. At 2 × AE90, the sigmoid Emax model predicted a mean onset time of 23.4 min and mean duration of 22.9 h. Interindividual variability (IIV) for AE50 was 49%. Typical ke0 half-life was 34.7 min (IIV = 52%) and steepness parameter 8.7 (IIV = 48%). None of the pharmacodynamic model parameters showed sex, age, or body weight dependency. CONCLUSIONS: A population pharmacokinetic/pharmacodynamic model was developed that quantitatively describes the sensory component of a femoral nerve block in orthopedic patients. Further clinical studies will be needed to validate the clinical relevance of this finding.

The reliability of the current perception threshold in volunteers and its applicability in a clinical setting.

BACKGROUND: Even though current perception threshold (CPT) has been used for evaluating the effectiveness of sensory block in patients before surgery, its reliability under controlled conditions has not been investigated. Two independent investigations were performed. The primary objective of the first study was to determine the test-retest reliability of CPT measures after repeated stimulations in a group of healthy volunteers. The primary objective of the second study was to evaluate the clinical applicability of this technique to assess the sensory onset of a femoral nerve block in patients undergoing knee surgery. METHODS: Thirty healthy subjects participated in 2 identical sessions, separated by at least 24 hours, in which CPTs were measured after 5 consecutive stimulations over the anteromedial aspect of the thigh. Similar measures were obtained in 15 orthopedic patients receiving a femoral nerve block with 20 mL of ropivacaine 0.5%. Test-retest reliability was assessed using intraclass correlation (ICC) and standard error of measurement (expressed as coefficient of variation [CV(SEM)]), whereas Student t test (P < 0.05) compared the increase in CPTs over baseline. RESULTS: Within-day ICC values ranged (% confidence interval [CI]) from 0.66 to 0.95 with a CV(SEM) of approximately 39% (% CI: 17%-58%). Between-day ICC values, ranging from 0.57 to 0.94 (CV(SEM): approximately 45%, % CI: 13%-71%), indicated that day-to-day CPT measurements are also variable. The current intensity needed for sensory perception in orthopedic patients significantly increased, varying from a mean CPT value of 82.5 ± 66.5 µA (SD) at time zero to an average of 481 ± 338 µA, 22 ± 8 minutes after the administration of the local anesthetic. CONCLUSIONS: CPT proved to be a reliable assessment tool for within-day sensory perception in healthy volunteers. Our study also suggests that CPT can be applied to characterize, in a quantitative manner, the sensory onset of a peripheral nerve block in a clinical setting, thereby supporting its use in future studies comparing different regional anesthetic modalities or approaches.

Replacing a double-lumen tube with a single-lumen tube or a laryngeal mask airway device to reduce coughing at emergence after thoracic surgery: a randomized controlled single-blind trial.

BACKGROUND: Coughing episodes occur frequently at extubation after thoracic surgery, and this may be due in part to the double-lumen tube (DLT). In this study, the DLT was replaced with either a single-lumen endotracheal tube (ETT) or a laryngeal mask airway (LMA) device or left in place, and the incidence of coughing at emergence was compared between the three groups. METHODS: Fifty-eight adults scheduled for thoracic surgery with a DLT were included. Exclusion criteria were an anticipated difficult airway, obesity, and contraindication to the use of an LMA ProSeal™ (LMA-P). After surgery but before emergence, patients were randomized to having the DLT (1) removed and replaced by an LMA-P (LMA-P Group), (2) removed and replaced by an ETT (ETT Group), or (3) left in place (DLT Group). The primary outcome was the number of coughing episodes at extubation. RESULTS: Among 184 patients screened, 124 did not meet inclusion criteria, and two patients, both in the ETT Group, were excluded after randomization, leaving 20, 18, and 20 patients in the LMA-P, ETT, and DLT Groups, respectively. There were fewer coughing episodes (median [quartiles]) in the LMA-P Group than in the DLT Group (0[0-1] vs 2[1-3], respectively; P = 0.01). In the DLT Group, 90% of patients coughed at least once. This incidence was not significantly different in the ETT Group (83%; P = 0.222) but was significantly reduced in the LMA-P Group (35%; P < 0.001). No patient had oxygen desaturation during airway exchange or at extubation. The incidence and severity of hoarseness and sore throat were similar in all groups. CONCLUSION: Coughing at extubation after thoracic surgery can be reduced if the DLT is replaced by an LMA-P before emergence. The number of patients in this trial was too small to evaluate the risks associated with exchanging the airway device. This trial was registered at ClinicalTrials.gov: NCT00925613.

[Hi-Fi simulation: Teaching crisis resource management to surgery residents]. / Simulation á haute fidélité: Moyen d'enseignement des principes de gestion de crises périopératoires aux residents de chirugie.

BACKGROUND: High-fidelity (HiFi) simulation has shown its effectiveness for teaching crisis resource management (CRM) principles, and our institutional experience in this area is mainly with anesthesiology residents. We recently added to our postgraduate curriculum a new CRM course designed to cater to the specific needs of surgical residents. AIM: This short communication describes the experience of the University of Montreal Simulation Centre (Centre d'Apprentissage des Attitudes et Habiletés Cliniques CAAHC) regarding HiFi simulationbased CRM and communication skills teaching for surgical residents. METHODS: Thirty residents agreed to participate in a simulation course with pre-established scenarios and educational CRM objectives on a voluntary basis. RESULTS: When surveyed immediately after the activity, all residents agreed that the educational objectives were well defined (80% "strongly agree" and 20% "agree"). The survey also showed that the course was well accepted by all participants (96% "strongly agree" and 4% "agree"). CONCLUSION: Further trials with randomized groups and more reliable assessment tools are needed to validate our results. Still, integrating HiFi simulation based CRM learning in the surgical residency curriculum seems like an interesting step.

Randomized prospective trial comparing two supraglottic airway devices: i-gel™ and LMA-Supreme™ in paralyzed patients.

PURPOSE: Many features can influence the choice of a supraglottic airway device (SAD), including ease of insertion, adequate ventilation pressures and lack of adverse effects. The goal of this randomized prospective trial was to compare the performance of the i-gel™ with that of the LMA-Supreme™. METHODS: One hundred adult patients (American Society of Anesthesiologists I-III) scheduled to undergo elective surgery under general anesthesia were randomized to either an i-gel (n = 50) or an LMA-Supreme (n = 50). The primary objective was to compare ventilation pressures. Secondary objectives included time and number of attempts needed to introduce the device, adverse effects, and repositioning. The endoscopic view of the glottic aperture and the position of the drain tubes in relation to the esophagus were also evaluated. RESULTS: The devices were inserted successfully in 46 (92%) patients in both groups. There was no significant difference in the [mean (SD)] leak pressure [i-gel: 23 (7) cm H2O vs LMA-Supreme: 21 (8) cm H2O; P = 0.14] or peak inspiratory pressure between both devices. Insertion time was shorter with the i-gel than with the LMA-Supreme [19 (7) sec vs 27 (17) sec, respectively; P = 0.003]. The vocal cords were completely visualized more often through the i-gel (70%) than through the LMA-Supreme (50%) (P = 0.007). Esophageal mucosa was easily visualized through the drain port in all but four patients, two patients in each group. There was no difference between groups regarding preoperative or postoperative complications. Postoperative patient discomfort was generally mild and comparable between both devices. CONCLUSION: Both the LMA-Supreme and the i-gel offer similar performance for positive pressure ventilation in paralyzed patients during general anesthesia. The i-gel was associated with a slightly faster insertion time and better fibrescopic visualization of the glottis. This trial was registered at Clinicaltrials.gov: NCT01001078.

Hyperthermic intraperitoneal chemotherapy with oxaliplatin as treatment for peritoneal carcinomatosis arising from the appendix and pseudomyxoma peritonei: a survival analysis.

BACKGROUND: Appendiceal peritoneal carcinomatosis (PC) is rare and its long-term prognosis is poor. The aim of this study was to evaluate the results of an aggressive treatment approach used in our institution for the last eight years. METHODS: Data from all patients with PC arising from the appendix were prospectively collected and analyzed. Treatment consisted of complete surgical cytoreduction (CRS), followed by hyperthermic intraperitoneal chemotherapy (HIPEC) with oxaliplatin (460 mg/m2) at 43°C over 30 minutes. Ronnett's histologic classification was used for tumor grading. RESULTS: Between February 2003 and April 2011, 78 patients underwent laparotomy with curative intent. The mean follow-up period was 33.7 months. A total of 58 patients received HIPEC, but 11 patients could not have CRS and received no HIPEC. Nine patients with a negative second-look surgery also received no HIPEC. The five-year overall survival for the entire cohort was 66.2%; 100% for the negative second-look patients, 77% for the HIPEC patients and 9% for the unresectable patients (P<0.0001). A total of 15 patients (25.9%) had isolated peritoneal recurrence, no patient had visceral recurrence only, and five patients (8.6%) had both. In regards to the five-year disease-free survival for the HIPEC patients, histologic grade (disseminated peritoneal adenomucinosis 100%, peritoneal mucinous carcinomatosis with intermediate features 40%, peritoneal mucinous carcinomatosis 20%; p=0.0016) and completeness of cytoreduction (CCR-0 56%, CCR-1 24%; P=0.0172) were prognostic factors. There was one postoperative mortality. The major complication rate for patients treated with HIPEC was 40%, including intra-abdominal abcess (17%), hemorrhage (12%) and anastomotic leak (10%). One patient in the HIPEC group experienced temporary grade II neuropathy and grade III thrombocytopenia. CONCLUSIONS: This therapeutic approach seems both feasible and safe in selected patients. Recurrence is, however, frequent and represents a challenge.

Mastering Sedation and Associated Respiratory Events through Simulation-Based Training: A Randomised Controlled Trial Involving Non-Anaesthesiology Residents.

Non-anaesthetists commonly administer procedural sedation worldwide, posing the risk of respiratory events that can lead to severe complications. This study aimed to evaluate whether simulation-based learning could lead to enhancements in the clinical proficiency of non-anaesthesiology residents in managing sedation and related respiratory complications. Following the evaluation of baseline clinical performance through a pre-test simulation, 34 residents were randomly allocated to either participate in an innovative simulation-based learning module (intervention group) or view a brief self-learning video (control group). After a one-month period, their clinical performance was assessed again in a post-test simulation involving respiratory arrest during procedural sedation. Two independent assessors rated each resident's performance using video recordings and a scoring tool with scores ranging from 0 to 19/19. The two assessments were averaged for each performance, and the pre- to post-test change was calculated for each resident. While baseline clinical performance was similar, mean (SD) increase in clinical performance was significantly greater in the intervention group than in the control group (+2.4 (1.6) points versus +0.8 (1.3) points, respectively; p = 0.002). Our simulation-based learning sedation module resulted in the enhanced management of sedation-related complications compared to baseline and minimal self-learning. Simulation-based medical education may offer an effective approach for equipping non-anaesthesiology residents with essential skills to mitigate risks associated with sedation. (ClinicalTrials.gov identifier: NCT02722226).