Orlando Hung

Laryngoscopic intubation: Learning and performance

Background Many healthcare professionals are trained in direct laryngoscopic tracheal intubation (LEI), which is a potentially lifesaving procedure. This study attempts to determine the number of successful LEI exposures required during training to assure competent performance, with special emphasis on defining competence itself. Methods Analyses were based on a longitudinal study of novices under training conditions in the operating room. The progress of 438 LEIs performed by the 20 nonanesthesia trainees was monitored by observation and videotape analysis. Eighteen additional LEIs were performed by experienced anesthesiologists to define the standard. A generalized linear, mixed-modelling approach was used to identify key aspects of effective training and performance. The number of tracheal intubations that the trainees were required to perform before acquiring expertise in LEI was estimated. Results Subjects performed between 18 and 35 laryngoscopic intubations. However, statistical modeling indicates that a 90% probability of a “good intubation” required 47 attempts. Proper insertion and lifting of the laryngoscope were crucial to “good” or “competent” performance of LEI. Traditional features, such as proper head and neck positions, were found to be less important under the study conditions. Conclusions This study determined that traditional LEI teaching for nonanesthesia personnel using manikin alone is inadequate. A reevaluation of current standards in LEI teaching for nonanesthesia is required.

Clinical trial of a new lightwand device (Trachlight) to intubate the trachea.

Background : Transillumination of the soft tissue of the neck using a lighted stylet (lightwand) is an effective and safe intubating technique. A newly designed lightwand (Trachlight) incorporates modifications to improve the brightness of the light source as well as flexibility. The goal of this study was to determine the effectiveness and safety of this device in intubating the trachea of elective surgical patients. Methods : Healthy surgical patients were studied. Patients with known or potential problems with intubation were excluded. During general anesthesia, the tracheas were intubated randomly using either the Trachlight or the laryngoscope. Failure to intubate was defined as lack of successful intubation after three attempts. The duration of each attempt was recorded as the time from insertion of the device into the oropharynx to the time of its removal. The total time to intubation (TTI), an overall measure of the ease of intubation, was defined as the sum of the durations of all (as many as three) intubation attempts. Complications, such as mucosal bleeding, lacerations, dental injury, and sore throat, were recorded. Results : Nine hundred fifty patients (479 in the Trachlight group and 471 in the laryngoscope group) were studied. There was a 1% failure rate with the Trachlight, and 92% of intubations were successful on the first attempt, compared with a 3% failure rate and an 89% success rate on the first attempt with the laryngoscope (P not significant). All failures were followed by successful intubation using the alternate device. The TTI was significantly less with the Trachlight compared with the laryngoscope (15.7 ± 10.8 vs. 19.6 ± 23.7 s). For laryngoscopic intubation, the TTI was longer for patients with limited mandibular protrusion and mentohyoid distance, with a larger circumference of the neck, and with a high classification according to Mallampatti et al. However, there was no relation between the TTI and any of the airway parameters for Trachlight. There were significantly fewer traumatic events in the Trachlight group than in the laryngoscope group (10 vs. 37). More patients complained of sore throat in the laryngoscope group than in the Trachlight group (25.3% vs. 17.1%). Conclusions : In contrast to laryngoscopy, the ease of intubation using the Trachlight does not appear to be influenced by anatomic variations of the upper airway. Intubation occasionally failed with the Trachlight but in all cases was resolved with direct laryngoscopy. The failures of direct laryngoscopy were resolved with Trachlight. Thus the combined technique was 100% successful in intubating the tracheas of all patients.

Lightwand intubation: II--Clinical trial of a new lightwand for tracheal intubation in patients with difficult airways.

Lightwands have been used to assist in the tracheal intubation of patients with difficult airways for many years. A new lightwand (Trachlight™) with a brighter light source and a flexible stylet permits both oral and nasal intubation under ambient light. This study reports the effectiveness of the Trachlight™ in tracheal intubation in patients with difficult airways. Two groups of patients were studied: Group 1 — patients with a documented history of difficult intubation or anticipated difficult airways; Group 2 — anaesthetized patients with an unanticipated failed laryngoscopic intubation. In Group I, the tracheas were intubated using the Trachlight™ with patients either awake or under general anaesthesia. In Group 2, tracheas were intubated under general anaesthesia using the Trachlight™. The time-to-intubation, number of attempts, failures, and complications during intubation for all patients were recorded. Two hundred and sixty-five patients were studied with 206 patients in Group 1, and 59 in Group 2. In most patients, the tracheas were intubated orally (183 versus 23 nasal) during general anaesthesia (202 versus 4 awake) in Group 1. Intubation was successful in all but two of the patients with a mean (± SD) time-to-intubation of 25.7 ± 20.1 sec (range 4 to 120 sec). The tracheas of these two patients were intubated successfully using a fibreoptic bronchoscope. Orotracheal intubation was successful in all patients in Group 2 using the Trachlight™ with a mean (± SD) time-to-intubation of 19.7 ± 13.5 sec. Apart from minor mucosal bleeding (mostly from nasal intubation), no serious complications were observed in any of the study patients. With proper preparation, this study has demonstrated that Trachlight™ is an effective and safe device to intubate the tracheas of elective surgical patients with a history of difficult airway in experienced hands.RésuméLe mandrin lumineux est utilisé pour faciliter l’intubation de la trachée depuis plusieurs années. Un nouveau mandrin lumineux (Trachlight™) avec une source lumineuse plus intense et un stylet flexible permet l’intubation orale et nasale à la lumière ambiante. Cette étude porte sur l’efficacité du Trachlight™ pour l’intubation trachéale de patients à voies aériennes difficiles d’accès. Deux groupes de patients sont étudiés: le groupe 1 est constitué de patients dont les antécédents d’intubation difficile sont documentés ou chez qui on anticipe un accès difficile aux voies aériennes; le groupe 2 comprend des patients dont l’intubation par laryngoscope a échoué inopinément. Dans le groupe 1, la trachée est intubée avec le Trachlight™ alors que le patient est éveillé ou complètement anesthésié. Dans le groupe 2, la trachée est intubée sous anesthésie générale avec le Trachlight™. Le temps requis pour l’intubation, le nombre de tentatives, les échecs et les complications survenant pendant l’intubation sont notés chez tous les patients. Deux cent soixante-cinq patients sont inclus dans l’étude, dont 206 dans le groupe 1 et 59 dans le groupe 2. Pour la plupart des patients du groupe 1, la trachée est intubée par la voie orale (183 vs 23 par le nez) pendant une anesthésie générale (202 vs 4 éveillés). L’intubation réussit dans tous les cas à l’exception de deux. La moyenne (± ET) pour la durée de l’intubation est de 25,7 ± 20,1 sec (de 4 à 120 sec). En ce qui concerne les deux échecs, l’intubation est réussie plus tard grâce à la fibroscopie. L’intubation orotrachéale est réussie chez tous les patients du groupe 2 avec le Trachlight™ et la moyenne pour la durée de l’intubation est de 19,7 ± 13,5 sec. A l’exception de saignements muqueux légers (causés surtout par l’intubation nasale), on n’observe pas de complications graves parmi les patients de cette étude. Avec une préparation appropriée, cette étude montre que le Trachlight™ constitue, pour des personnes d’expérience, un outil efficace et sûr pour intuber la trachée de patients programmés qui possèdent des voies aériennes d’accès difficile.

Thiopental pharmacodynamics. II. Quantitation of clinical and electroencephalographic depth of anesthesia.

This study examined the relationship among pseudo-steady-state (constant) serum thiopental concentrations, clinical anesthetic depth as assessed by several perioperative stimuli, and the electroencephalogram (EEG). Twenty-six ASA physical status 1 or 2 patients participated in the study. Two constant serum thiopental concentrations were maintained in each patient using a computer-controlled infusion pump. The first randomly assigned target serum concentration of 10-30 micrograms/ml was maintained for 5 min to allow serum:brain equilibration. Then the following stimuli were applied at 1-min intervals: verbal command, tetanic nerve stimulation, trapezius muscle squeeze, and laryngoscopy. A second, higher, randomly assigned target serum concentration of 40-90 micrograms/ml was then achieved and maintained by the computer-controlled infusion pump. The previously described stimuli were reapplied, after which laryngoscopy and intubation was performed. A positive response was recorded if purposeful extremity movement or coughing was observed. Using the quantal movement or cough response and the measured constant serum thiopental concentration, the probability of no movement to each stimulus was characterized using logistic regression. The serum thiopental concentrations that produced a 50% probability of no movement response for the clinical stimuli were as follows: 15.6 micrograms/ml for verbal command, 30.3 micrograms/ml for tetanic nerve stimulation, 39.8 micrograms/ml for trapezius muscle squeeze, 50.7 micrograms/ml for laryngoscopy, and 78.8 micrograms/ml for laryngoscopy followed by intubation. The EEG was analyzed using aperiodic waveform analysis to derive the number of waves per second. A biphasic relationship between constant serum thiopental concentration and the EEG number of waves per second was observed. Loss of responsiveness to verbal stimulation occurred when the EEG was activated at 15-18 waves/s.(ABSTRACT TRUNCATED AT 250 WORDS)

The difficult airway with recommendations for management – Part 1 – Difficult tracheal intubation encountered in an unconscious/induced patient

AbstractBackgroundPreviously active in the mid-1990s, the Canadian Airway Focus Group (CAFG) studied the unanticipated difficult airway and made recommendations on management in a 1998 publication. The CAFG has since reconvened to examine more recent scientific literature on airway management. The Focus Group’s mandate for this article was to arrive at updated practice recommendations for management of the unconscious/induced patient in whom difficult or failed tracheal intubation is encountered. MethodsNineteen clinicians with backgrounds in anesthesia, emergency medicine, and intensive care joined this iteration of the CAFG. Each member was assigned topics and conducted reviews of Medline, EMBASE, and Cochrane databases. Results were presented and discussed during multiple teleconferences and two face-to-face meetings. When appropriate, evidence- or consensus-based recommendations were made together with assigned levels of evidence modelled after previously published criteria.ConclusionsThe clinician must be aware of the potential for harm to the patient that can occur with multiple attempts at tracheal intubation. This likelihood can be minimized by moving early from an unsuccessful primary intubation technique to an alternative “Plan B” technique if oxygenation by face mask or ventilation using a supraglottic device is non-problematic. Irrespective of the technique(s) used, failure to achieve successful tracheal intubation in a maximum of three attempts defines failed tracheal intubation and signals the need to engage an exit strategy. Failure to oxygenate by face mask or supraglottic device ventilation occurring in conjunction with failed tracheal intubation defines a failed oxygenation, “cannot intubate, cannot oxygenate” situation. Cricothyrotomy must then be undertaken without delay, although if not already tried, an expedited and concurrent attempt can be made to place a supraglottic device.RésuméContexteActif au milieu des années 1990, le Canadian Airway Focus Group (CAFG), un groupe dédié à l’étude des difficultés imprévues dans la prise en charge des voies aériennes, a émis des recommandations sur ce sujet dans une publication datant de 1998. Le CAFG s’est réuni à nouveau pour passer en revue la littérature scientifique récente concernant la prise en charge des voies aériennes. Dans cet article, le CAFG s’est donné pour mission d’émettre des recommandations visant la prise en charge du patient inconscient ou anesthésié qui présente des difficultés d’intubation significatives.MéthodeDix-neuf cliniciens ayant une formation en anesthésie, en médecine d’urgence ou en soins intensifs composent le CAFG actuel. Les participants ont passé en revue des sujets précis en consultant les bases de données Medline, EMBASE et Cochrane. Les résultats de ces revues ont été présentés et discutés dans le cadre de téléconférences et de deux réunions en personne. Lorsqu’indiqué, des recommandations fondées sur des données probantes ou sur un consensus ont été émises. Le niveau de confiance attribué à ces recommandations a aussi été défini.ConclusionLe clinicien doit avoir conscience des lésions qu’il peut infliger lors de tentatives multiples d’intubation trachéale. Il est possible d’éviter de telles lésions en abandonnant rapidement une technique d’intubation infructueuse afin d’opter pour une méthode alternative (ou ‘plan B’) à condition que l’oxygénation par masque facial ou par l’utilisation d’un dispositif supraglottique s’avère possible. Nonobstant la ou les techniques choisies, un maximum de trois tentatives infructueuses mène à la conclusion qu’il s’agit d’un échec d’intubation et devrait inciter le clinicien à adopter une stratégie de retrait. Une situation dans laquelle il est impossible de procéder à l’oxygénation du patient à l’aide d’un masque facial, d’un dispositif supraglottique ou de l’intubation endotrachéale est qualifiée de scénario cannot intubate, cannot ventilate. Il est alors impératif de procéder sans délai à une cricothyrotomie, à moins que l’insertion d’un dispositif supraglottique n’ait été tentée. Celle-ci peut alors être effectuée rapidement et parallèlement à la réalisation de la cricothyrotomie.

The difficult airway with recommendations for management – Part 2 – The anticipated difficult airway

BackgroundAppropriate planning is crucial to avoid morbidity and mortality when difficulty is anticipated with airway management. Many guidelines developed by national societies have focused on management of difficulty encountered in the unconscious patient; however, little guidance appears in the literature on how best to approach the patient with an anticipated difficult airway.MethodsTo review this and other subjects, the Canadian Airway Focus Group (CAFG) was re-formed. With representation from anesthesiology, emergency medicine, and critical care, CAFG members were assigned topics for review. As literature reviews were completed, results were presented and discussed during teleconferences and two face-to-face meetings. When appropriate, evidence- or consensus-based recommendations were made, and levels of evidence were assigned.Principal findingsPreviously published predictors of difficult direct laryngoscopy are widely known. More recent studies report predictors of difficult face mask ventilation, video laryngoscopy, use of a supraglottic device, and cricothyrotomy. All are important facets of a complete airway evaluation and must be considered when difficulty is anticipated with airway management. Many studies now document the increasing patient morbidity that occurs with multiple attempts at tracheal intubation. Therefore, when difficulty is anticipated, tracheal intubation after induction of general anesthesia should be considered only when success with the chosen device(s) can be predicted in a maximum of three attempts. Concomitant predicted difficulty using oxygenation by face mask or supraglottic device ventilation as a fallback makes an awake approach advisable. Contextual issues, such as patient cooperation, availability of additional skilled help, and the clinician’s experience, must also be considered in deciding the appropriate strategy.ConclusionsWith an appropriate airway evaluation and consideration of relevant contextual issues, a rational decision can be made on whether an awake approach to tracheal intubation will maximize patient safety or if airway management can safely proceed after induction of general anesthesia. With predicted difficulty, close attention should be paid to details of implementing the chosen approach. This should include having a plan in case of the failure of tracheal intubation or patient oxygenation.RésuméContexteUne planification adaptée est essentielle afin d’éviter la morbidité et la mortalité lorsqu’on prévoit des difficultés dans la prise en charge des voies aériennes. De nombreuses recommandations émises par des sociétés nationales mettent l’emphase sur la gestion des difficultés rencontrées chez le patient inconscient. Toutefois, il n’existe dans la littérature que peu de suggestions sur la façon d’approcher le patient chez qui les difficultés sont prévisibles.MéthodeAfin de passer en revue ce sujet et d’autres, le Canadian Airway Focus Group (CAFG), un groupe dédié à l’étude de la prise en charge des voies aériennes, a été reformé. Les membres du CAFG représentent diverses spécialités soit l’anesthésiologie, la médecine d’urgence et les soins intensifs. Chaque participant avait pour mission de passer en revue des sujets précis. Les résultats de ces revues ont été présentés et discutés dans le cadre de téléconférences et de deux réunions en personne. Lorsqu’indiqué, des recommandations fondées sur des données probantes ou sur un consensus ont été émises. Le niveau de confiance attribué à ces recommandations a aussi été défini.Constatations principalesPlusieurs éléments permettant de prédire la laryngoscopie directe difficile sont connus. Des études plus récentes décrivent aussi les éléments permettant d’anticiper des difficultés lors de la ventilation au masque facial, de la vidéolaryngoscopie, de l’utilisation d’un dispositif supraglottique ou de la réalisation d’une cricothyrotomie. Tous ces éléments doivent être pris en compte lors de l’évaluation du patient chez qui des difficultés sont anticipées lors de la prise en charge des voies aériennes. De nombreuses études rapportent une morbidité accrue liée à des tentatives multiples d’intubation trachéale. Planifier de procéder à l’intubation trachéale après l’induction de l’anesthésie générale n’est donc recommandé que pour les patients chez qui la ou les techniques prévues ne nécessiteront pas plus de trois tentatives. Il est recommandé de prioriser d’emblée une approche vigile dans les cas où des difficultés reliées à l’utilisation du masque facial ou d’un dispositif supraglottique sont prévues. L’établissement d’une stratégie de prise en charge doit tenir compte d’éléments contextuels telles la collaboration du patient, la disponibilité d’aide supplémentaire et de personnel qualifié, et l’expérience du clinicien.ConclusionUne évaluation adaptée des voies aériennes ainsi que les éléments contextuels propres à chaque situation sont les bases qui permettent de déterminer de manière rationnelle si l’intubation trachéale vigile est apte à optimiser la sécurité du patient, ou si la prise en charge des voies aériennes peut être réalisée de manière sécuritaire après l’induction de l’anesthésie générale. Lorsqu’on prévoit des difficultés, une attention particulière doit être portée aux détails nécessaires au succès de l’approche envisagée. De plus, il convient d’avoir un plan en cas d’échec de l’intubation trachéale ou si l’oxygénation du patient s’avérait difficile.

Lightwand intubation using the Trachlight: a brief review of current knowledge.

PurposeAbout 1% to 3% of laryngoscopic intubations can be difficult or impossible. Light-guided intubation has been proven to be an effective, safe, and simple technique. This article reviews current knowledge about the newer version lightwand: the Trachlight™ (TL).SourceTo determine its clinical utility and limitations, we reviewed the current literature (book and journal articles) on the TL since its introduction in 1995.Principal findingsTL has been shown to be useful both in oral and nasal intubation for patients with difficult airways. It may also be useful in “emergency” situations or when direct laryngoscopy or fiberoptic endoscopy is not effective, such as with patients who have copious secretions or blood in the oropharynx. TL can also be used for tracheal intubation in conjunction with other devices (laryngeal mask airway -LMA-, intubating LMA, direct laryngoscopy). However, TL should be avoided in patients with tumours, infections, trauma or foreign bodies in the upper airway.ConclusionsBased on the clinical reports available, the TL has proven to be a useful option for tracheal intubation. In addition, the device can also be used together with other intubating devices, such as the intubating LMA and the laryngoscope, to improve intubating success rates. A clear understanding of the principle of transillumination of the TL, and an appreciation of its indications, contraindications, and limitations, will improve the effectiveness of the device as well as reducing the likelihood of complications. Finally, regular practice with the TL with routine surgical patients requiring tracheal intubation will further improve intubation success rates.RésuméObjectifLa fréquence d’intubation difficile ou impossible varie de 1% à 3%. L’intubation trachéale avec le Trachlight™ (TL) représente une technique efficace, sûre et simple.Dans cet article nous voulons réviser les connaissances actuelles sur le stylet lumineux TL.MéthodePour déterminer les applications et les limitations du TL, nous avons révisé la littérature (livres ou revues) sur le TL à partir de son introduction en 1995.ResultatsLe TL permet une intubation oro-ou naso-trachéale dans différentes situations d’intubation difficile. Cette technique d’intubation avec le TL peut également être utile dans des situations d’urgence ou quand l’intubation trachéale avec le bronchoscope n’est pas indiquée, comme chez les patients qui présentent des sécrétions abondantes ou du sang dans l’oropharynx.Le TL peut également être utilisé pour l’intubation trachéale en même temps que d’autres dispositifs (masque laryngé, masque laryngé pour intubation, laryngoscopie directe). Cependant l’usage du TL devrait être évité chez les patients présentant une tumeur, une infection, un traumatisme ou un corps étranger dans les voies aériennes.ConclusionSelon les rapports cliniques à notre disposition, nous pouvons affirmer que le TL représente une solution de remplacement utile à la laryngoscopie traditionnelle. Le TL peut également être utilisé avec d’autre dispositifs comme le masque laryngé et la laryngoscopie directe pour augmenter le taux de réussite de l’intubation trachéale.En conclusion, la pratique régulière avec le TL et une connaissance de ses indications, contre-indications et limitations, peut améliorer l’efficacité du dispositif et réduire la probabilité de complications.

Lightwand intubation: I — A new lightwand device

Tracheal intubation under direct vision using a laryngoscope can be challenging and difficult even in experienced hands. Transillumination of the soft tissues of the neck using a lightedstylet (lightwand) is one of many effective alternative intubating techniques developed during the past several decades. While many versions of lightwand have been available, each has its limitations. A newly developed lightwand (Trachlight™) has incorporated many design modifications. It has a brighter bulb, permitting intubation under ambient light in most cases. A retractable stiff wire within the wand adds flexibility to facilitate both oral and nasal intubation. The flexible wand also allows visual (transillumination) guide to proper placement of the tip of the tracheal tube in the trachea. The Trachlight™ does have some limitations. It is a light-guided technique in which there is no direct visualization of the upper airway structures. It should be avoided in patients with known anatomical abnormalities of the upper airway and used with caution in patients in whom transillumination of the anterior neck may not be achieved adequately. As with any intubating technique, successful intubation using the Trachlight™ relies on the preparation of the patient and the operator’s skill and experience.RésuméMême entreprise par des personnes expérimentées, l’intubation sous vision directe avec un laryngoscope peut être laborieuse. La transillumination des tissus du cou avec un mandrin lumineux constitue une des techniques de rechange développées au cours des dernières décennies. Bien que plusieurs versions du mandrin lumineux soient disponibles, elles ont toutes leurs limites. Un nouveau mandrin lumineux (Trachlight™) incorpore plusieurs modifications au design original. L’éclairage est intense, ce qui permet l’intubation à la lumière ambiante dans la plupart des cas. Un stylet rétractile à l’intérieur du mandrin ajoute de la flexibilité ce qui facilite l’intubation orale et nasale. Le mandrin flexible permet aussi de guider visuellement (par transillumination) le bout de la canule endotrachéale dans la trachée. Le Trachlight™ a aussi ses limites. Il s’agit d’une technique d’orientation par la lumière qui ne perm et pas de visualiser directement les structures des voies aériennes supérieures. Elle devrait être évitée dans les cas d’anomalies connue de l’anatomie des voies aériennes supérieures et utilisée avec prudence lorsque la transillumination des structures antérieures du cou ne peut être réalisée correctement. Comme pour toutes les techniques d’intubation, le succès dépend de la préparation du patient, et de l’expérience et de l’habileté de l’intubateur.

Thiopental Pharmacodynamics I. Defining the Pseudo–Steady-state Serum Concentration–EEG Effect Relationship

To assess depth of anesthesia for intravenous anesthetics using clinical stimuli and observed responses, it is necessary to achieve constant serum concentrations of drug that result in constant biophase or central nervous system concentrations. The goal of this investigation was to use a computer-controlled infusion pump (CCIP) to obtain constant serum thiopental concentrations and use the electroencephalogram (EEG) as a measure of thiopentals central nervous system drug effect. The number of waves per second obtained from aperiodic waveform analysis was used as the EEG measure. A CCIP was used in six male volunteers to attain rapidly and then maintain for 6-min time periods the following pseudo-steady-state constant serum thiopental target concentrations: 10, 20, 30, and 40 micrograms/ml. The median performance error (bias) of the CCIP using 149 measurements of thiopental serum concentrations in six subjects was +5%, and the median absolute performance error (accuracy) was 16%. Following the step change in serum thiopental concentration, the EEG number of waves per second stabilized within 2-3 min and the remained constant until the target serum thiopental concentration was changed. When the constant serum thiopental concentration was plotted against the number of waves per second for each subject, a biphasic serum concentration versus EEG effect relationship was seen. This biphasic concentration:response relationship was characterized with a nonparametric pharmacodynamic model. The awake, baseline EEG was 10.6 waves/s; at peak activation the EEG was 19.1 waves/s and occurred at a serum thiopental concentration of 13.3 micrograms/ml. At a serum thiopental concentration of 31.2 micrograms/ml the EEG had slowed to 10.6 waves/s (back to baseline) and at 41.2 micrograms/ml was 50% below the baseline, awake value. Zero waves per second occurred at serum thiopental concentrations greater than 50 micrograms/ml. Using a CCIP it is possible to establish constant serum thiopental concentration rapidly and characterize the concentration versus EEG drug effect relationship.

Pharmacokinetics of Inhaled Liposome-encapsulated Fentanyl

BackgroundPulmonary administration of fentanyl solution can provide satisfactory but brief postoperative pain relief. Liposomes are microscopic phospholipid vesicles that can entrap drug molecules. Liposomal delivery of fentanyl has the potential to control the uptake of fentanyl by the lungs and th