Richard M. Levitan

Assessment of laryngeal view: Percentage of glottic opening scorevs Cormack and Lehane grading

PurposeTo examine the intra- and inter-rater reliability of two methods that categorize laryngeal view during direct laryngoscopy, the Cormack-Lehane grading system and a new scale, the percentage of glottic opening (POGO) scale.MethodsSeven anesthesiologists from the University of Pennsylvania Health System viewed 25 identical pairs of slides of laryngeal views during direct laryngoscopy. Each anesthesiologist rated the 50 slides for both Cormack-Lehane grades and POGO scores. The latter CL replaces grades 1 and 2 C-L grades with a percentage of glottic opening: the POGO score. Inter and intra-physician reliability for the Cormack-Lehane grades were determined using the kappa statistic analysis, comparison of POGO scores was performed using the intraclass correlation coefficients (r1).ResultsThe POGO score had a better inter and intra-physician reliability than the Cormack-Lehane grading system. The intra-physician reliability for the POGO score was very good with an average interclass r1 value of 0,88. The inter-physician score was good with a r1 of 0.73. The Cormack-Lehane grading system had excellent intraphysician concordance (average kappa = 0.83.) but the inter-physician reliability was poor (kappa = 0.16.)ConclusionThe Cormack-Lehane grading system has very poor inter-physician reliability. The lack of interphysician reliability with Cormack-Lehane grading calls into question the results of previous studies in which different laryngoscopists used this method to assess laryngeal view. The POGO score appears to have good intra and inter-rater reliability. It has several theoretical advantages and may prove to be more useful for research studies in direct laryngoscopy.RésuméObjectifVérifier la fiabilité intra et interobservateur de deux méthodes de classification de la vue du larynx pendant la laryngoscopie directe: le système de cotation de Cormack-Lehane et une nouvelle échelle, le pourcentage d’ouverture glottique (POG).MéthodeSept anesthésiologistes de l’University of Pennsylvania Health System ont visionné 25 paires identiques de diapositives du larynx sous laryngoscopie directe. Chaque anesthésiologiste a coté les 50 diapositives selon les échelons Cormack-Lehane et les scores POG. Cette dernière échelle remplace les rangs 1 et 2 C-L par un pourcentage d’ouverture glottique: le score POG. La fiabilité inter et intraobservateur des rangs Cormack-Lehane a été déterminée par une analyse statistique kappa, la comparaison des scores POG a été réalisée en utilisant des coefficients de corrélation interclasses (r1).RésultatsLe POG a fourni une meilleure fiabilité inter et intraobservateur que le système de cotation Cormack-Lehane. La fiabilité intraobservateur du score POG a été très bonne, la valeur interclasse moyenne r1 étant de 0,88. Le score interobservateur a été bon selon un r1 de 0,73. Le système de Cormack-Lehane a donné une excellente concordance intraobservateur (kappa moyen = 0,83) mais la fiabilité interobservateur a été pauvre (kappa = 0,16).ConclusionLe système de cotation Cormack-Lehane a présenté une très pauvre fiabilité interobservateur. Cette lacune remet en question les résultats d’études antérieures où différents médecins ont utilisé la méthode pour évaluer la vue du larynx. Le score POG semble avoir une bonne fiabilité intra et interévaluateur. Il présente certains avantages théoriques et peut se révéler plus utile lors de recherches en laryngoscopie directe.

The Complexities of Tracheal Intubation With Direct Laryngoscopy and Alternative Intubation Devices

Intubation research on both direct laryngoscopy and alternative intubation devices has focused on laryngeal exposure and not the mechanics of actual endotracheal tube delivery or insertion. Although there are subtleties to tracheal intubation with direct laryngoscopy, the path of tube insertion and the direct line of sight are relatively congruent. With alternative intubation devices, this is not the case. Video or optical elements in alternative intubation devices permit looking around the curve of the tongue, without a direct line of sight to the glottic opening. With these devices, laryngeal exposure is generally the simple part of the procedure, and conversely, tube delivery to the glottic opening and advancement into the trachea are sometimes not straightforward. This article presents the mechanical and optical complexities of endotracheal tube insertion in both direct laryngoscopy and alternative devices. An understanding of these complexities is critical to facilitate rapid tracheal intubation and to minimize unsuccessful attempts.

Alternating day emergency medicine and anesthesia resident responsibility for management of the trauma airway: A study of laryngoscopy performance and intubation success

Abstract Study objective We compare laryngoscopy performance and overall intubation success in trauma airways when primary airway management alternated between emergency medicine and anesthesia residents on an every-other-day basis. Methods Data on all trauma intubations during approximately 3 years were prospectively collected. Primary airway management was assigned to emergency department (ED) residents on even days and anesthesia residents on odd days. Emergency medicine residents intubated patients who arrived without notification or who needed immediate intubation before anesthesia arrived. The study was conducted in an inner-city, Level I trauma center with approximately 50,000 ED patients and 1,800 major trauma cases a year. Main outcomes were success or failure at laryngoscopy and the number of laryngoscopy attempts needed for intubation. Results Six hundred fifty-eight trauma patients were intubated during the study period. Laryngoscopy was successful in 654 of 656 cases. Two (0.3%) patients underwent cricothyrotomy after failed laryngoscopy, and 2 (0.3%) patients had awake nasal intubation without laryngoscopy. The specific number of laryngoscopy attempts was unknown in 6 cases (3 from each service), resulting in 650 cases for laryngoscopy performance analysis. Overall, 87% of patients were intubated on first attempt, and 3 or more attempts occurred in 2.9% of patients. Laryngoscopy performance by service (broken down by 1, 2, and ≥3 attempts) was as follows: emergency medicine 86.4%, 11%, and 2.6% versus anesthesia 89.7%, 6.7%, and 3.6%. Analysis by service was done by using Wilcoxon Mann-Whitney testing ( P =.225). Conclusion There were no differences in laryngoscopy performance and intubation success in trauma airways managed on an every-other-day basis by emergency medicine versus anesthesia residents. [ Ann Emerg Med. 2004;43:48-53.]

Use of the intubating laryngeal mask airway by medical and nonmedical personnel.

The intubating laryngeal mask airway (ILMA) is a newly available device designed to allow for blind endotracheal intubation and treatment of patients with difficult airways. We studied the intubation success rates and speed with initial use of this device on an intubation manikin to determine whether this device might be easily used by trained and untrained personnel. Rapid and successful intubation with a device requiring limited or no training could have widespread implications for both health care providers and laypersons. The study consisted of 2 parts. In part 1, health care providers with intubation experience, health care providers without prior intubation experience, and nonmedical personnel were instructed to enter a room and intubate a manikin using the ILMA. A single page set of schematic directions was provided within the ILMA setup. The main outcomes were the intubation success rate and the time required for successful ventilation and intubation. In part 2, participants were retested after a standardized <60 second device demonstration. The 111 participants in the study included 44 emergency physicians (40%), 21 anesthesiologists (19%), and 46 other medical or nonmedical personnel (41%). On first attempted use of the device, and with no prior training, 59% of all participants successfully intubated the manikin. Attending and resident physicians had an 83% initial success rate. The median time to ventilation was 47 seconds, and the median time from ventilation until intubation was 29 seconds. Following the <60 second demonstration, 108 of 111 (97%) participants achieved success, with the median time to ventilation 18 seconds, and the median time from ventilation until intubation 17 seconds. All attending and resident physicians succeeded in intubation following the demonstration. Success rates on first attempt correlated with level of training, prior intubation experience, and prior LMA use (all P < .001). After a <60 second demonstration, medical and nonmedical personnel with and without prior intubation training can successfully use the ILMA to rapidly establish an airway in a manikin model. The ILMA should be further studied to determine if it may permit endotracheal intubation by first responders, paramedical personnel, and other medical staff with limited or no laryngoscopy skills.

AIRWAY MANAGEMENT AND DIRECT LARYNGOSCOPY A Review and Update

Direct laryngoscopy is the direct visualization of the larynx while using a rigid laryngoscope to distract the structures of the upper airway. This article reviews the anatomy relevant to laryngoscopy and then presents a stepwise approach to the procedure. Alternative intubation techniques, positioning, laryngoscopy blades, and stylets are then covered. Pharmacologic adjuncts are discussed briefly as they relate to the difficult airway and incorporation into overall airway management.

A videographic analysis of laryngeal exposure comparing the articulating laryngoscope and external laryngeal manipulation.

Activation of the articulating laryngoscope and external laryngeal manipulation (ELM) improve laryngeal exposure during direct laryngoscopy. We used a head-mounted direct laryngoscopy imaging system and a previously validated scoring system for assessing laryngeal view (the percentage of glottic opening or POGO score) on 33 adult patients undergoing laryngoscopy. On each patient, we videotaped the initial laryngeal exposure (blade not activated), the view with activation of the blade, and the view with operator-directed external laryngeal manipulation. The video recordings were reviewed and the laryngeal view assessed with POGO scores. POGO scores improved with blade activation in 9/33 (27%) of patients vs 28/33 (85%) of patients with ELM. In nearly half of patients studied (16/33, 48%) POGO scores decreased with blade activation. We conclude that ELM is superior to articulating laryngoscope blade activation in improving POGO scores during laryngoscopy on adult patients in standard sniffing position. Using recordings from a direct laryngoscopy video system, we compared laryngeal views in 33 patients with a special articulating laryngoscope blade to views achieved by external laryngeal manipulation (pressing on the patient’s neck). Laryngeal exposure, which is important for placement of tracheal tubes, was better with external laryngeal manipulation.

Video Laryngoscopy, Regardless of Blade Shape, Still Requires a Backup Plan

Babbington first looked around the curvature of the tongue and performed mirror laryngoscopy in 1829. Kirstein pioneered direct laryngoscopy in 1895. For the next 100 years, clinicians inserted tracheal tubes with this technique. The last decade has yielded another advancement, the video laryngoscope. Combining charged metal oxide sensor video cameras and light emitting diode illumination, these novel devices provide a new way to look around the curve of the tongue, offering a new approach to intubation. Although direct laryngoscopy has a remarkably effective ( 99%) overall intubation success rate, video laryngoscopy provides improved visualization of the larynx and visual confirmation of tube placement and has dramatically expanded the margin of safety in airway management. In this issue of Annals, Mosier et al provide a look at the effectiveness of video laryngoscopy in a large academic emergency department that experiences a high volume of trauma cases. They found no difference in overall or first-pass success rates between the hyperangulated GlideScope and the more conventionally shaped Storz C-Mac, an important finding because many proponents of the GlideScope have argued that standard laryngoscope blades (ie, those with a Macintosh shape) are nonanatomic, unsophisticated instruments that should be relegated to a museum. The Storz C-Mac combines a standard metal Macintosh blade design with an incorporated video camera, arguably combining the best of both video laryngoscopy and direct laryngoscopy techniques. In known difficult airway cases, particularly those with fixedneck deformities, small thyromental spaces, etc, I can imagine instances in which a hyperangulated blade (GlideScope or Storz D blade) would be advantageous. Conversely, a potential advantage of the Storz C-Mac size 4 blade is that it has a longer reach down the airway than the equivalent GlideScope blade, allowing options for epiglottis control (ie, direct lifting if needed). If the video camera gets obscured (ie, by blood or vomitus), you still have a brilliantly illuminated low-profile Mac blade that can be used as a direct laryngoscope. Additionally, tube delivery is more straightforward with the Storz C-Mac because it

Front-of-neck airway meets front-of-neck simulation: improving cricothyroidotomy skills using a novel open-access three-dimensional model and the Airway App

To the Editor, Although anesthesiologists, intensivists, and emergency physicians rarely perform cricothyroidotomy, these specialists must maintain the knowledge, decisionmaking, and procedural skill sets to perform cricothyroidotomy quickly and safely. The 2015 Difficult Airway Society guidelines recommend bougie-assisted scalpel cricothyrotomy coupled with regular simulated practice. Regardless of the technique used, the training must be realistic, addressing both technical and non-technical skills and facilitating reflection and data gathering. We outline a novel approach to cricothyrotomy training that we introduced at a recent airway workshop. We are eager to share it, receive feedback, and further develop this airway education and patient safety initiative. Previously, as in many centres, our airway workshops focused on the acquisition of manual skills using mannequins and isolated pig tracheas. As the Canadian Airway Focus Group emphasizes, however, manual skills are only one aspect required for reliable patient rescue in a ‘‘cannot intubate/cannot oxygenate’’ emergency. Specifically, we wished to address the oft-cited reluctance to cut another human’s neck. Accordingly, we sought to create a tool that would increase manual skills and could be coupled with human factors’ training. Nontechnical steps are just as likely to go wrong as technical endeavors, so mental preparedness and cognitive rehearsal are essential. The use of mannequins is commonly criticized for unrealistic anatomy/haptic feedback and lack of ‘‘stress inoculation’’. Although isolated pig tracheas provide more realistic airway anatomy and the ‘‘feel’’ of tissue, there are no real-life hindrances (e.g., from a patient’s chin or thick neck) to overcome with problemsolving. Both mannequins and pig models may also inadvertently send a message that cricothyrotomy requires an elaborate or expensive setup. Inspired by the lecture given by Dr. Ciaran McKenna, we created a three-dimensional (3D) cricothyroidotomy model based on the original 3D anatomic program from The University of Dundee and BodyParts 3D: The Database Center for Life Science Computer Science departments. To achieve the realism of performing cricothyrotomy on a real person, the authors conceptualized modifications to enable this model to be fitted on the neck of a real person. The original Dundee model was modified to include a slightly larger cricothyroid space to accommodate a 6.0 mm endotracheal tube. The posterior aspect of the model is flat and solid. Therefore, despite using scalpels, L. V. Duggan (&) S. L. Lockhart K. R. Romano University of British Columbia, Vancouver, BC, Canada e-mail: laura.duggan@fraserhealth.ca; lauravduggan@gmail.com

The Role of Optical Stylets

Optical stylets are versatile airway tools now offered in many different designs that are useful for placing endotracheal tubes (ETTs) and confirming location, either used independently, with laryngoscopes, or with supraglottic airways (SGAs). There are wide variations in optical stylet length, malleability, and light sources. Their only common feature is that they provide imaging through an ETT. As they are passed beyond the vocal cords they all permit tracheoscopy.

The glidescope video laryngoscope in the hands of novice users: Seeing the larynx does not correlate with intubation success

Study objectives: Rescue intubation devices should be easy to use. The Glidescope Video Laryngoscope (GVL) uses a miniature video camera built within a curved laryngoscope. The camera position and wide field of view create laryngeal visualization by a monitor in almost any patient. Because of its traditional laryngoscope shape and method of insertion, the GVL should be easy to use, with fast initial skill acquisition. The objective of this study is to assess the intubation performance of novice users of the GVL. Methods: Sixteen participants (11 emergency physicians, 4 residents, 1 physicians assistant) used the GVL on 3 randomly ordered, nonembalmed cadavers. All were easy laryngoscopies with standard equipment. Participants observed 1 demonstration of the GVL and were told to shape the tube stylet as recommended by the manufacturer. Each attempt was recorded and timed using a digital VCR connected to the GVL monitor. Success was defined as tracheal intubation; failure was defined by the inability to intubate the trachea. Results: Laryngeal view was excellent in all 48 intubation attempts (percentage of glottic opening scores >90%). Overall, 36 (75%) of 48 attempts succeeded, with a mean intubation time of 76 seconds (95% confidence interval [CI] 58 to 94 seconds). Seven of 36 successful intubations occurred in 30 seconds or less. Nine of 16 participants succeeded on 3 of 3 cadavers; 1 failed on 3 of 3. Success by cadaver varied from 15 of 16 to 10 of 16, with mean success times per cadaver from 48 seconds (95% CI 31 to 65 seconds) to 108 seconds (95% CI 73 to 143 seconds). Performance was dependent on the specific cadaver and not related to the order of attempts: first cadaver attempt success rate was 13 of 16 (mean time 86±31 seconds) versus third cadaver success rate of 10 of 16 (mean time 74±38 seconds). Conclusion: In this study, novices obtained excellent laryngeal views with the GVL but tracheal tube placement—through a monitor and procedurally similar to laparoscopic surgery—was awkward, slow, and often unsuccessful. GVL difficulty varied considerably between cadavers. Three attempts did not produce competency in our study.