Alese Wagner

Thoracic and lumbar epidural analgesia via the caudal approach using electrical stimulation guidance in pediatric patients: a review of 289 patients.

BackgroundNerve stimulation guidance (Tsui test) has been reported to be an effective alternative to radiographic imaging for proper catheter placement. The purpose of this study was to examine the success rate and complications of continuous caudal epidural analgesia since the implementation of routine use of the Tsui test at the authors’ institution. MethodsThe authors examined prospectively collected data in their pediatric pain service database from 289 children who had attempted caudal placement of a lumbar or thoracic catheter between 1999 and 2002. ResultsIn five patients (aged 5 months–1.6 yr), the catheter did not thread to the desired level and was abandoned in the operating room (technical success rate, 98.2%). Of the remaining 284 patients, the overall analgesic success rate of all caudal route epidural analgesia procedures was 84.9%. There was no significant difference in adequate pain control (success) in infants (aged 1 day–1 yr) versus older children (aged younger than 1 yr). The most common adverse effects were pruritus (26.1%) and nausea and vomiting (16.9%). Of the patients in our study, 57.7% had urinary catheters in situ; of those who did not have a catheter placed, 20.8% experienced urinary retention. The incidence of respiratory depression was 4.2%, but the administration of naloxone for severe respiratory depression was never necessary. Three percent of catheters were removed because of suspected contamination, but no epidural abscesses or systemic infection were noted. ConclusionsThe results of this study suggest that epidural catheter placement via the caudal approach using the Tsui test is an effective and reasonable alternative to direct lumbar and thoracic epidural analgesia in pediatric patients.

Electrophysiologic effect of injectates on peripheral nerve stimulation

Background and Objectives: A small volume of local anesthetic or normal saline abolishes the muscle twitch induced by a 1ow current (0.5 mA) during electrolocation. This study examines the hypothesis that the mechanism of this phenomenon is primarily the electrophysiologic effect of the injectate on the electrical current density at the needle tip. Methods: Five pigs were studied. An insulated Tuohy needle was inserted in each pig toward the left and right brachial plexuses and the left and right femoral nerves. The needle was advanced until corresponding motor responses were observed at each site, using a current of 0.5 mA. The effect of injecting 1 mL each of normal saline and 5% dextrose in water (NS and D5W) on muscle twitch was investigated at all 20 needle insertion sites. Changes in the conductive area induced by the injectates were also demonstrated using gel electrophoresis. Results: In all cases, the muscle twitches were abolished immediately after the injection of NS and recovered instantaneously after a subsequent injection of D5W. The electrical resistance between the needle and the ground electrodes decreased instantly after the NS injection. The resistance not only recovered but also increased after the injection of D5W. In the gel electrophoresis experiment, the results demonstrated that the expanded conductive area induced by the saline column surrounding the insulated needle was similar to that observed with the uninsulated needle. Conclusion: The injection of a conducting solution (i.e., NS) rendered the current that was previously sufficient to elicit a motor response (0.5 mA) ineffective. The most likely reason for this change is that the conductive area surrounding the stimulating needle expanded after the injection and dispersion of the conducting solution (i.e., NS), thereby reducing the current density at the target nerve. This effect can be reversed by injecting a nonconducting solution (i.e., D5W) via the stimulating needle.

Regional Anaesthesia in the Elderly

The number of elderly patients presenting for anaesthesia and surgery has increased exponentially in recent years. Regional anaesthesia is frequently used in elderly patients undergoing surgery. Although the type of anaesthesia (general versus regional anaesthesia) has no substantial effect on perioperative morbidity and mortality in any age group; it intuitively makes sense that elderly patients would benefit from regional anaesthesia because they remain minimally sedated throughout the procedures and awaken with excellent postoperative pain control. However, a multitude of factors influence the outcome, such as the type, duration and invasiveness of the operation, co-existing medical and mental status of the patient and the skill and expertise of the anaesthesiologist and surgeon. These factors make it difficult to decide if and when one technique is equivocally better than another. Thus, it is more important to optimise the overall management of the patient during the perioperative period and, in most cases, it is the quality of the anaesthetic administered rather than the type of anaesthetic which is most important. Sedatives used for regional anaesthesia in the elderly should be short acting, easy to administer, have a low adverse effect profile and high safety margin. Midazolam, lorazepam, ketamine, propofol and low-dose opioids have been successfully used for sedation in the elderly. Aging affects the pharmacokinetics and pharmacodynamics of local anaesthetics, composition and characteristics of tissues and organs within the body, and physiological functions of the body. Changes in the systematic absorption, distribution and clearance of local anaesthetics lead to an increased sensitivity, decreased dose requirement and a change in the onset and duration of action in the elderly. Decreases in neural population, neural conduction velocity and inter-Schwann cell distance can lead to an increased sensitivity to local anaesthetics in the elderly. The addition of an opioid and epinephrine (adrenaline) has been shown to be useful in central neuraxial blockade. Epinephrine also can prolong the duration of peripheral nerve blocks. However, caution must be exercised as epinephrine has the potential for causing ischaemic neurotoxicity in peripheral nerves. Regional anaesthesia appears to be safe and beneficial in elderly patients; however, every anaesthetic administered must be assessed on a case-by-case basis and particular consideration should be given to the health status of the patient, the operation being performed and the expertise of the anaesthesiologist.

The incidence of laryngospasm with a "no touch" extubation technique after tonsillectomy and adenoidectomy.

In this case series, we evaluated the incidence of laryngospasm using a clearly defined awake tracheal extubation technique in 20 children undergoing elective tonsillectomy with or without adenoidectomy. This technique required patients to be turned to the recovery position at the end of the procedure before discontinuing the volatile anesthetics. No further stimulation, besides continuous oximetry monitoring, was allowed until the patients spontaneously woke up (“no touch” technique). The incidence of laryngospasm, oxygen saturation, and coughing was recorded. No cases of laryngospasm, oxygen desaturation, or severe coughing occurred in our patient population.

Combined propofol and remifentanil intravenous anesthesia for pediatric patients undergoing magnetic resonance imaging

Background : A prospective observational case series of children receiving light general anesthesia for magnetic resonance imaging (MRI) was performed. Our purpose was to examine the merit of anesthesia and recovery/discharge times of combined remifentanil and propofol total intravenous anesthesia (TIVA) in spontaneously breathing children.

The threshold current in the intrathecal space to elicit motor response is lower and does not overlap that in the epidural space: a porcine model

PurposeUsing electrical epidural stimulation, a current of 1 to 10 mA is required to confirm the presence of the tip of an epidural catheter in the epidural space. The purpose of this study was to examine the hypothesis that the threshold current required to elicit a motor response in the intrathecal space is significantly lower than that in the epidural space in a porcine model.MethodsFour 20-kg pigs were used in this experiment. Eighteen gauge, insulated, Tuohy needles were advanced into the epidural space using the loss of resistance technique at five different spinal levels in each pig. When the epidural space was entered, an electrical current was applied to the needle and increased progressively until a motor response was elicited. The needle was then further advanced until cerebrospinal fluid (CSF) was observed or until the needle had been advanced a maximum of 1 cm. At this point, the current was reapplied and increased until motor activity was evident.ResultsA total of 20 needles were inserted in four pigs. The current required to produce a motor response in the epidural space was 3.45 ± 0.73 mA (mean ± SD). The current required to produce a motor response in the intrathecal space (entry confirmed by the presence of CSF) was 0.38 ± 0.19 mA (mean ± SD). Two needles were advanced 1 cm without obtaining CSF but the current thresholds were similar to those obtained when CSF was evident (0.4 mA and 0.3 mA, respectively).ConclusionThe threshold current of an insulated needle required to elicit a motor response in the intrathecal space, was significantly (P < 0.01) lower than that in the epidural space in a porcine model.RésuméObjectifEn utilisant une stimulation péridurale électrique, un courant de 1 à 10 mA est nécessaire pour confirmer la présence de la pointe d’un cathéter dans l’espace péridural. Notre objectif était de vérifier l’hypothèse voulant que le courant seuil nécessaire pour obtenir une réponse motrice dans l’espace intrathécal soit significativement plus faible que dans l’espace péridural chez un modèle porcin.MéthodeQuatre porcs de 20 kg ont été utilisés. Des aiguilles Tuohy isolées, de calibre 18, ont été poussées dans l’espace péridural selon la technique de perte de résistance à cinq niveaux différents chez chaque animal. Une fois l’aiguille introduite, un courant électrique était appliqué et augmenté progressivement jusqu’à l’obtention d’une réaction motrice. L’aiguille était ensuite avancée plus loin jusqu’à ce qu’on observe du liquide céphalorachidien (LCR) ou de 1 cm tout au plus. À ce point, le courant était réappliqué et augmenté jusqu’à ce que l’activité motrice soit évidente.RésultatsUn total de 20 aiguilles ont été insérées chez quatre porcs. Le courant requis pour produire une réponse motrice dans l’espace péridural a été de 3,45 ± 0,73 mA (moyenne ± écart type). Le courant requis dans l’espace intrathécal (entrée confirmée par la présence de LCR) a été de 0,38 ± 0,19 mA (moyenne ± écart type). Deux aiguilles ont été poussées de 1 cm sans qu’on observe de LCR, mais les courants minimaux ont été similaires à ceux qu’on a obtenus en présence de LCR (0,4 mA et 0,3 mA, respectivement).ConclusionLe courant seuil, transmis par une aiguille isolée, nécessaire pour produire une réponse motrice dans l’espace intrathécal a été significativement (P < 0,01) plus faible que dans l’espace péridural chez un modèle porcin.

Threshold Current of an Insulated Needle in the Intrathecal Space in Pediatric Patients

A threshold current of <1 mA has been suggested to be sufficient to produce a motor response to electrical stimulation in the intrathecal space. We designed this study to determine the threshold current needed to elicit motor activity for an insulated needle in the intrathecal space. Twenty pediatric patients aged 7.3 ± 3.9 yr scheduled for lumbar puncture were recruited. After sedation with propofol, patients were turned to the lateral position and an 18-gauge or 20-gauge introducer needle was placed at the L4-5 level through which an insulated 24-gauge Pajunck unipolar needle (with a Sprotte tip and stylet) was inserted. The needle was advanced into the intrathecal space as suggested by the presence of a “pop.” At this point, a nerve stimulator was attached to the insulated needle and the current was gradually increased until motor activity was evident. The needle hub was checked for cerebrospinal fluid. If cerebrospinal fluid was not present, the needle was advanced further until cerebrospinal fluid was present. The threshold current was retested. The mean current in the intrathecal space required to elicit a motor response was 0.6 ± 0.3 mA (range, 0.1–1 mA). In 19 patients, the twitches were observed at the L4-5 myotomes and 1 patient had twitches at L2. Twitches were observed unilaterally in 19 children and bilaterally in one child. This confirms the hypothesis that the threshold current in the intrathecal space is <1 mA and that it differs significantly from the threshold currents reported for electrical stimulation in the epidural space.

Threshold Current for an Insulated Epidural Needle in Pediatric Patients

We designed this study to determine the threshold current for nerve stimulation of an insulated needle in the epidural space. The intended dermatome was identified using the bony landmarks of the spine. An 18-gauge insulated Tuohy needle was inserted perpendicularly to the skin and advanced until “loss of resistance” was felt. A nerve stimulator was then connected to the insulated needle. Twenty patients were studied using an insulated Tuohy needle and one patient was studied using a noninsulated Tuohy needle. Muscle twitch was elicited with a current of 11.1 ± 3.1 mA (mean ± sd) in all patients in which an insulated needle was used. Muscle twitches were within 2 myotomes of the intended level (based on bony landmarks). Muscle twitch was not elicited with a noninsulated needle. After catheter threading, positive stimulation tests were elicited via epidural catheters in all patients (4.9 ± 2.3 mA). Postoperative radiograph confirmed all catheter placements within 2 myotomes of the muscle twitches. Electrical stimulation may be a useful adjuvant tool to loss of resistance for confirming proper thoracic epidural needle placement. The threshold current criteria for an insulated needle (6–17 mA) would be higher than the original Tsui test criteria described for an epidural catheter (1–10 mA) in the epidural space.

Declining randomized clinical trials from Canadian anesthesia departments

Objectif La productivite en recherche a ete estimee par les articles provenant des departements ďanesthesiologie des universites canadiennes sur une periode de cinq ans. Les articles ont ete classifies selon la methodologie de ľetude.PurposeThe research productivity was estimated by publications from anesthesiology departments at Canadian universities over a five-year period, and the articles published were classified into several study designs.MethodsIn this observational study, the MEDLINE database was searched for publications listed by anesthesiology departments at Canadian universities as the primary corresponding source from 2000-2004. Abstracts were reviewed and each publication categorized into its respective methodological design. Impact factors of the journals in which the articles appeared were taken into consideration. “Total impact score” was defined as the total number of articles from a particular journal in a particular year multiplied by the impact factor value. Changes in overall publication numbers over the five-year period were compared and analyzed using Pearson correlation coefficients.ResultsTotal Canadian anesthesia publications remained constant from 2000-2004. In this five-year time frame, the University of Toronto had the highest number of publications (271) followed by the University of Montreal (86), and McGill University (84). These universities conducted primarily randomized controlled trials (RCTs) whereas smaller Canadian universities mainly published case reports, reviews, and cohort studies. The number of RCTs conducted seems to be decreasing whereas the number of case reports and reviews being published are remaining constant over the five-year period.ConclusionAlthough overall numbers in anesthesia publications do not suggest a significant decline, the number of RCTs decreased during the years 2000-2004. The quality of anesthesia research appears to be comparable to those in other medical specialties, with larger institutions conducting RCTs and smaller institutions publishing more case reports.RésuméObjectifLa productivité en recherche a été estimée par les articles provenant des départements ďanesthésiologie des universités canadiennes sur une période de cinq ans. Les articles ont été classifiés selon la méthodologie de ľétude.MéthodePour cette étude observationnelle, nous avons recherché dans MEDLINE les articles publiés par les départements ďanesthésiologie des universités canadiennes en tant que source primaire conforme entre 2000 et 2004. Les résumés ont été examinés et chaque article catégorisé selon sa méthodologie respective. Les facteurs ďimpact des revues dans lesquelles les articles paraissaient ont été considérés. «Le score ďimpact total» a été défini comme le total des articles ďune revue publiés au cours ďune année et multiplié par la valeur du facteur ďimpact. Les variations du nombre total ďarticles publiés sur cinq ans ont été comparées et analysées à ľaide des coefficients de corrélation de Pearson.RésultatsLe nombre total ďarticles publiés sur ľanesthésie au Canada est demeuré constant entre 2000 et 2004. Pendant cette période, ľUniversité de Toronto a publié le plus ďarticles (271) suivie de ľUniversité de Montréal (86) et de ľuniversité McGill (84). Ces institutions ont surtout réalisé des études randomisées et contrôlées (ERC) tandis que les universités canadiennes plus.

Déclin des études randomisées et contrôlées des départements ďanesthésie canadiens

Objectif La productivite en recherche a ete estimee par les articles provenant des departements ďanesthesiologie des universites canadiennes sur une periode de cinq ans. Les articles ont ete classifies selon la methodologie de ľetude.PurposeThe research productivity was estimated by publications from anesthesiology departments at Canadian universities over a five-year period, and the articles published were classified into several study designs.MethodsIn this observational study, the MEDLINE database was searched for publications listed by anesthesiology departments at Canadian universities as the primary corresponding source from 2000-2004. Abstracts were reviewed and each publication categorized into its respective methodological design. Impact factors of the journals in which the articles appeared were taken into consideration. “Total impact score” was defined as the total number of articles from a particular journal in a particular year multiplied by the impact factor value. Changes in overall publication numbers over the five-year period were compared and analyzed using Pearson correlation coefficients.ResultsTotal Canadian anesthesia publications remained constant from 2000-2004. In this five-year time frame, the University of Toronto had the highest number of publications (271) followed by the University of Montreal (86), and McGill University (84). These universities conducted primarily randomized controlled trials (RCTs) whereas smaller Canadian universities mainly published case reports, reviews, and cohort studies. The number of RCTs conducted seems to be decreasing whereas the number of case reports and reviews being published are remaining constant over the five-year period.ConclusionAlthough overall numbers in anesthesia publications do not suggest a significant decline, the number of RCTs decreased during the years 2000-2004. The quality of anesthesia research appears to be comparable to those in other medical specialties, with larger institutions conducting RCTs and smaller institutions publishing more case reports.RésuméObjectifLa productivité en recherche a été estimée par les articles provenant des départements ďanesthésiologie des universités canadiennes sur une période de cinq ans. Les articles ont été classifiés selon la méthodologie de ľétude.MéthodePour cette étude observationnelle, nous avons recherché dans MEDLINE les articles publiés par les départements ďanesthésiologie des universités canadiennes en tant que source primaire conforme entre 2000 et 2004. Les résumés ont été examinés et chaque article catégorisé selon sa méthodologie respective. Les facteurs ďimpact des revues dans lesquelles les articles paraissaient ont été considérés. «Le score ďimpact total» a été défini comme le total des articles ďune revue publiés au cours ďune année et multiplié par la valeur du facteur ďimpact. Les variations du nombre total ďarticles publiés sur cinq ans ont été comparées et analysées à ľaide des coefficients de corrélation de Pearson.RésultatsLe nombre total ďarticles publiés sur ľanesthésie au Canada est demeuré constant entre 2000 et 2004. Pendant cette période, ľUniversité de Toronto a publié le plus ďarticles (271) suivie de ľUniversité de Montréal (86) et de ľuniversité McGill (84). Ces institutions ont surtout réalisé des études randomisées et contrôlées (ERC) tandis que les universités canadiennes plus.