Daniel Chartrand

Guidelines to the Practice of Anesthesia Revised Edition 2010.

OverviewThe Guidelines to the Practice of Anesthesia Revised Edition 2013 (the guidelines) were prepared by the Canadian Anesthesiologists’ Society (CAS), which reserves the right to determine their publication and distribution. Because the guidelines are subject to revision, updated versions are published annually. The Guidelines to the Practice of Anesthesia Revised Edition 2013 supersedes all previously published versions of this document. Although the CAS encourages Canadian anesthesiologists to adhere to its practice guidelines to ensure high-quality patient care, the society cannot guarantee any specific patient outcome. Each anesthesiologist should exercise his or her own professional judgement in determining the proper course of action for any patient’s circumstances. The CAS assumes no responsibility or liability for any error or omission arising from the use of any information contained in its Guidelines to the Practice of Anesthesia.RésuméLe Guide d’exercice de l’anesthésie, version révisée 2013 (le guide), a été préparé par la Société canadienne des anesthésiologistes (SCA), qui se réserve le droit de décider des termes de sa publication et de sa diffusion. Le guide étant soumis à révision, des versions mises à jour sont publiées chaque année. Le Guide d’exercice de l’anesthésie, version révisée 2013, remplace toutes les versions précédemment publiées de ce document. La SCA incite les anesthésiologistes du Canada à se conformer à son guide d’exercice pour assurer une grande qualité des soins dispensés aux patients, mais elle ne peut garantir les résultats d’une intervention. Chaque anesthésiologiste doit exercer son jugement professionnel pour déterminer la méthode d’intervention la mieux adaptée à l’état du patient. La SCA n’accepte aucune responsabilité de quelque nature que ce soit découlant d’erreurs ou d’omissions ou de l’utilisation des renseignements contenus dans son Guide d’exercice de l’anesthésie.

Efficacy and Costs of Patient-controlled Analgesia versus Regularly Administered Intramuscular Opioid Therapy

Background Many studies have shown in the efficacy of patient‐controlled analgesia (PCA). However, it is not clear whether PCA has clinical or economic benefits in addition to efficient analgesia. The current study was designed to evaluate these issues by comparing PCA with regularly administered intramuscular injections of opioids after hysterectomy. Methods This prospective study included 126 patients who underwent abdominal hysterectomy and were randomly assigned to receive PCA or regularly timed intramuscular injections of morphine during a period of 48 h. Doses were adjusted to provide satisfactory analgesia in both treatment groups. Pain at rest and with movement, functional recovery, drug side effects, and patient satisfactory were measured using rating scales and questionnaires. The costs of PCA and intramuscular therapy were calculated based on personnel time and drug and material requirements. Results Comparable analgesia was observed with the two treatment methods, with no significant differences in the incidence of side effects or patient satisfaction. The medication dosage had to be adjusted significantly more frequently in the intramuscular group than in the PCA patients. The PCA did not favor a faster recuperation time compared with intramuscular therapy in terms of times of ambulation, resumption of liquid and solid diet, passage of bowel gas, or hospital discharge. The results of the economic evaluation, which used a cost‐minimization model and sensitivity analyses, showed that PCA was more costly than regular intramuscular injections despite the fact that no costs for the pump were included in the analyses. Cost differences in nursing time favoring PCA were offset by drug and material costs associated with this type of treatment. Conclusions Compared with regularly scheduled intramuscular dosing, PCA is more costly and does not have clinical advantages for pain management after hysterectomy. Because of the comparable outcomes, the general use of PCA in similar patients should be questioned.

Comparison between patient-controlled analgesia and intramuscular meperidine after thoracotomy

A prospective randomized controlled study was performed to assess the efficacy and safety of patient-controlled analgesia (PCA) in patients undergoing thoracotomy. This method was compared with a conventional pain management technique consisting of regularly scheduled im injections of analgesics. Forty adult patients were randomly assigned to receive intravenous PCA or im meperidine treatment over a 48-hr period after surgery. Care was taken to optimize analgesia in patients of both groups. The MeGill Pain Questionnaire, visual analogue and verbal-numeric scales were administered at regular intervals to measure various components of the patients’pain experience, degree of pain relief, adverse side effects and overall treatment efficacy. Functional recovery after surgery was also examined. The results showed good and comparable analgesia with both pain-control methods. However, a greater number of patients receiving im injections required dosage adjustments than in the PCA group. Patients’ and nurses’ evaluations of overall treatment efficacy also favoured PCA treatment. There were no major group differences in the side effect profile. Recovery pattern was also comparable in the two groups except for the length of hospitalisation. There were fewer long-stay patients in the PCA than in the im group. Meperidine intake was similar in both groups but considerable interpatient variation was seen. In conclusion, PCA is a safe, effective and individualized treatment method for controlling pain after thoracotomy. There appears to be some clinical advantages of PCA over im dosing regimens for analgesia after thoracotomy.RésuméUne étude prospective dûment contrôlée fut effectuée afin d’évaluer l’efficacité et la sécurité de l’auto-analgésie intraveineuse (patient-controlled analgesia: PCA) chez des patients ayant subi une thoractomie. Cette méthode était comparée à un mode conventionnel d’analgésie où des injections intramusculaires (im) d’analgésiques étaient administrées de façon régulière. Quarante patients adultes furent assignés au hasard à l’un ou l’autre groupe de traitement où de la mépéridine était adminsitrée soit en mode PCA, soit en mode im. L’étude s’est échelonnée sur une période de 48 hr après la chirurgie. L’obtention d’une analgésie optimale a fait l’objet d’une attention particulière et ce, chez les patients des deux groupes. Le questionnaire MeGill sur la douleur de même que des échelles de type visuel analogique et verbal-numérique furent administrés à intervalles fréquents afin de mesurer différentes composantes de la douleur des patients, le degré de soulagement, les effets secondaires et l’efficacité globale du traitement. Certains paramètres de récupération fonctionnelle ont également été mesurés. Les résultats ont démontré une analgésie adéquate et comparable avec les deux types de traitement. Toutefois, un nombre plus élevé de patients du groupe im a nécessité des changements de dosage par rapport au groupe PCA. Les mesures d’efficacité globale obtenues en fin de traitement auprès des patients et des infirmières militaient également en faveur du mode PCA. Le profil des effets secondaires ne montrait pas de différence majeure entre les deux groupes. Les paramètres de récupération étaient également comparables sauf pour le séjour hospitalier qui était moindre chez les patients du groupe PCA. La consommation de mépéridine était similaire chez les deux groupes mais les quantités variaient considérablement d’un patient à l’autre. En conclusion, le PCA apparaît être une méthode efficace et sécuritaire pour soulager la douleur post-thoracotomie; elle foumit un traitement individualisé et avantageux par rapport au mode traditionnel d’injections im.

Diaphragmatic and abdominal muscle activity after endoscopic cholecystectomy

We studied diaphragmatic and abdominal muscle activity immediately and 16 h after laparoscopic cholecystectomy (LAPC). Tidal volumes (sVT), partitioning of VT between the rib cage and the abdomen, and esophageal, gastric, and transdiaphragmatic pressures were recorded for 5 min every 15 min up to 90 min after the end of anesthesia in 10 young patients submitted to an elective LAPC. All had chest radiographs in full inspiration and expiration as well as lung function tests (LFTs) before and 16 h after surgery. In 5 of the 10 patients, thoracoabdominal patterns of breathing were also measured before both LFTs. After LAPC, VT did not change. There was no significant shift from abdominal to thoracic respiration. No paradoxical respiration developed. Functional residual capacity (FRC) and residual volume (RV) remained normal. However, all measures of LFTs requiring maximum inspiratory effort decreased up to 20%. Tonic and phasic activity of the abdominal muscle appeared early in the recovery period and disappeared after 75 min. The diaphragm adjusted to this additional load so that VT remained constant. These results indicate that diaphragm function is intact during quiet breathing after LAPC, but slightly reduced when maximum effort is needed. However, this represents a net gain over the changes previously described after classic “open” cholecystectomy (OC).

Attenuation of the 40-hertz auditory steady state response by propofol involves the cortical and subcortical generators.

Background:The 40-Hz auditory steady state response (40-Hz ASSR) provides a reliable marker of anesthetic-induced unconsciousness. Brain electric source analysis indicates that the 40-Hz ASSR arises from cortical and subcortical generators. The authors used source analysis to assess the effect of propofol anesthesia on the cerebral generators of the 40-Hz ASSR. They also examined the effect of propofol on two auditory evoked potentials of cortical origin: the N1 and the sustained potential. Methods:Eleven healthy human volunteers were anesthetized with propofol given in target-concentration mode at the minimal concentration causing unconsciousness. The 40-Hz ASSR was recorded before, during, and after anesthesia. The source model consisted of five concurrently active generator dipoles: two in the contralateral auditory cortex (one tangentially oriented, one radially oriented), two in the ipsilateral auditory cortex (same orientations), and one in the midline brainstem. Results:During anesthesia, the strength of the cortical and brainstem dipoles was reduced to the same extent (to 54% of baseline for the four cortical dipoles pooled vs. 53% for the brainstem dipole). Dipole strength during anesthesia was significantly less (P < 0.01) than during baseline and recovery for both cortical and brainstem dipoles. The N1 and sustained potential were no longer recordable during anesthesia. Conclusions:The attenuation of the 40-Hz ASSR during propofol anesthesia results from a reduction of similar magnitude of the activity of the cortical and brainstem generators. The N1 and sustained potential are so profoundly attenuated during propofol anesthesia that they are no longer recordable from the scalp.

The effect of changing end-expiratory pressure on respiratory system mechanics in open- and closed-chest anesthetized, paralyzed patients.

The decrease in functional residual capacity (FRC) with anesthesia may cause lung volume to decrease below closing volume, thereby impairing oxygenation.Increasing end-expiratory pressure (EEP) reexpands atelectatic areas in anesthetized, ventilated patients, but its effect on pulmonary mechanics is less well understood. We studied the effect of varying EEP on the mechanical behavior of the respiratory system in patients undergoing either closed (Group 1) or open-chest (Group 2) surgical procedures. We measured airway opening pressure (Pao), flow (V), and esophageal pressure (Pes) (in Group 1 only) at EEPs of 0, 2.5, 5, and 10 cm H2 O. Dynamic elastance (E) and resistance (R) for the respiratory system (RS), the lung (L), and the chest wall (CW) were estimated by fitting the Equation P= RV + EV + K to the measured data by multiple linear regression where P was either Pao, Pes, or Pao-Pes. Group 1 E (L) decreased with increases in EEP to 5 cm H2 O and then began to increase with EEP above this level. The same occurred in Group 2 before opening the chest. After opening the chest in Group 2, EL increased as EEP increased at all values above 0 cm H2 O. The magnitudes of RRS and RL were similar in both groups of subjects and in each group these quantities decreased with increases in EEP. Dynamic EL responded differently to changes in EEP in subjects with open-chest and closed-chest procedures. We attribute this difference to overdistension of the remaining ventilable lung tissue at all levels of EEP in open-chest patients. (Anesth Analg 1995;81:279-86)

Guidelines to the Practice of Anesthesia Revised Edition 2012@@@Guide d’exercice de l’anesthésie Édition révisée 2012

OverviewThe Guidelines to the Practice of Anesthesia Revised Edition 2012 (the guidelines) were prepared by the Canadian Anesthesiologists’ Society (CAS), which reserves the right to determine their publication and distribution. Because the guidelines are subject to revision, updated versions are published annually. Whereas previous versions of the guidelines appeared as special supplements to the Canadian Journal of Anesthesia (the Journal), this edition of the guidelines is published within the Journal. This allows for improved archiving and online access to complement the printed version—a new offering for CAS members and Journal subscribers. The Guidelines to the Practice of Anesthesia Revised Edition 2012 supersedes all previously published versions of this document. Although the CAS encourages Canadian anesthesiologists to adhere to its practice guidelines to ensure high-quality patient care, the society cannot guarantee any specific patient outcome. Each anesthesiologist should exercise his or her own professional judgement in determining the proper course of action for any patient’s circumstances. The CAS assumes no responsibility or liability for any error or omission arising from the use of any information contained in its Guidelines to the Practice of Anesthesia.RésuméLe Guide d’exercice de l’anesthésie, version révisée 2012 (le guide), a été préparé par la Société canadienne des anesthésiologistes (SCA), qui se réserve le droit de décider des termes de sa publication et de sa diffusion. Le guide étant soumis à révision, des versions mises à jour sont publiées chaque année. Alors que les versions précédentes du guide étaient publiées comme suppléments spéciaux du Journal canadien d’anesthésie (le Journal), cette édition du guide est publiée dans le Journal. Cette modification permet un archivage plus efficace ainsi qu’un accès en ligne pour compléter la version imprimée, une nouvelle offre aux membres de la SCA et aux abonnés au Journal. Le Guide d’exercice de l’anesthésie, version révisée 2012, remplace toutes les versions précédemment publiées de ce document. La SCA incite les anesthésiologistes du Canada à se conformer à son guide d’exercice pour assurer une grande qualité des soins dispensés aux patients, mais elle ne peut garantir les résultats d’une intervention. Chaque anesthésiologiste doit exercer son jugement professionnel pour déterminer la méthode d’intervention la mieux adaptée à l’état du patient. La SCA n’accepte aucune responsabilité de quelque nature que ce soit découlant d’erreurs ou d’omissions ou de l’utilisation des renseignements contenus dans son Guide d’exercice de l’anesthésie.

Guidelines to the Practice of Anesthesia Revised Edition 2011@@@Guide d’exercice de l’anesthésie Édition révisée 2011

OverviewThe Guidelines to the Practice of Anesthesia Revised Edition 2011 (the guidelines) were prepared by the Canadian Anesthesiologists’ Society (CAS), which reserves the right to determine their publication and distribution. Because the guidelines are subject to revision, updated versions are published annually. Whereas previous versions of the guidelines appeared as special supplements to the Canadian Journal of Anesthesia (the Journal), this edition of the guidelines is published within the Journal. This allows for improved archiving and online access to complement the printed version—a new offering for CAS members and Journal subscribers. The Guidelines to the Practice of Anesthesia Revised Edition 2011 supersedes all previously published versions of this document. Although the CAS encourages Canadian anesthesiologists to adhere to its practice guidelines to ensure high-quality patient care, the society cannot guarantee any specific patient outcome. Each anesthesiologist should exercise his or her own professional judgement in determining the proper course of action for any patient’s circumstances. The CAS assumes no responsibility or liability for any error or omission arising from the use of any information contained in its Guidelines to the Practice of Anesthesia.RésuméLe Guide d’exercice de l’anesthésie, version révisée 2011 (le guide), a été préparé par la Société canadienne des anesthésiologistes (SCA), qui se réserve le droit de décider des termes de sa publication et de sa diffusion. Le guide étant soumis à révision, des versions mises à jour sont publiées chaque année. Alors que les versions précédentes du guide étaient publiées comme suppléments spéciaux du Journal canadien d’anesthésie (le Journal), cette édition du guide est publiée dans le Journal. Cette modification permet un archivage plus efficace ainsi qu’un accès en ligne pour compléter la version imprimée, une nouvelle offre aux membres de la SCA et aux abonnés au Journal. Le Guide d’exercice de l’anesthésie, version révisée 2011, remplace toutes les versions précédemment publiées de ce document. La SCA incite les anesthésiologistes du Canada à se conformer à son guide d’exercice pour assurer une grande qualité des soins dispensés aux patients, mais elle ne peut garantir les résultats d’une intervention. Chaque anesthésiologiste doit exercer son jugement professionnel pour déterminer la méthode d’intervention la mieux adaptée à l’état du patient. La SCA n’accepte aucune responsabilité de quelque nature que ce soit découlant d’erreurs ou d’omissions ou de l’utilisation des renseignements contenus dans son Guide d’exercice de l’anesthésie.

Measurement of pleural pressure with oesophageal catheter-tip micromanometer in anaesthetized humans

In spontaneously breathing anaesthetized subjects, we studied a new technique for the measurement of changes in pleural pressure. Seven ASA physical status I patients undergoing general anaesthesia (enflurane 1–2 MAC, nitrous oxide 50%, and oxygen) for minor orthopaedic surgery were studied in the supine position. Changes in oesophageal pressure (ΔPes) were measured by means of a cathetertip pressure transducer. This micromanometer was positioned according to an occlusion test where ΔPes were compared with the changes in airway opening pressure (ΔPao). Optimizing the signal/noise ratio, we observed a linear relationship between ΔPes and ΔPao. In each patient, the ΔPes/ΔPao relationship was highly reproducible. Using the linear regression analysis to characterize the ΔPes/ΔPao relationship, we have developed a different approach for the positioning of oesophageal catheter. After statistical analysis of the observed ΔPes/ΔPao relationship, a “calibration” factor can be used in order to correct the observed slope of the ΔPes/ΔPao relationship to its theoretical value. We conclude that an oesophageal cathetertip micromanometer can be used in anaesthetized supine patients to measure changes in pleural pressure.RésuméChez des volontaires anesthésiés et respirant spontanément, nous avons étudié une nouvelle technique de mesure des variations de pression pleurale. Sept patients normaux (ASA I) devant subir une chirurgie orthopédique mineure sous anesthésie generate (enflurane 1–2 MAC, protoxyde d’azote 50%, et oxygene) ont été étudiés en décubitus dorsal. Les variations de pression œsophagienne (ΔPes) étaient mesurées au moyen d’un microcapteur de pression situé à l’extrémité d’un cathéter. Ce micromanomètre émit positionné selon un test d’occlusion où les ΔPes sont comparés aux variations de pression à l’ouverture des voies aériennes (ΔPao). En optimalisant le rapport signal/ bruit, nous avons observé une relation linéaire entre les ΔPes et les ΔPao. Chez chacun de nos patients, la relation ΔPes/ΔPao était hautement reproductible. Utilisant l’analyse de régression linéaire pour caractériser la relation ΔPes/ΔPao, nous avons développé une approche différente pour le positionnement d’un cathéter œsophagien. Aprés analyse statistique de la relation ΔPes/ΔPao observée, un facteur de “calibration” pent être utilisé pour corriger la penle observée de la relation ΔPes/ ΔPao à sa valeur théorique. Nous concluons done qu’un micromanomètre œsophagien peut être utilisé pour mesurer les variations de pression pleurale chez les patients anesthésiés et places en decubitus dorsal.

Facile synthesis of multinuclear complexes based on a tetra(4-pyridyl)amidinate dirhodium(II) dimer

Four rhenium(I) chromophores attached to a dirhodium(n) core form a new hexametallic light-harvesting assembly as characterised by X-ray crystallography, UV-vis spectroscopy and electrochemistry.