Comparison of Glidescope Core, C-MAC Miller and conventional Miller laryngoscope for difficult airway management by anesthetists with limited and extensive experience in a simulated Pierre Robin sequence: A randomized crossover manikin study.

BACKGROUND: Video laryngoscopy is an effective tool in the management of difficult pediatric airway. However, evidence to guide the choice of the most appropriate video laryngoscope (VL) for airway management in pediatric patients with Pierre Robin syndrome (PRS) is insufficient. Therefore, the aim of this study was to compare the efficacy of the Glidescope® Core™ with a hyperangulated blade, the C-MAC® with a nonangulated Miller blade (C-MAC® Miller) and a conventional Miller laryngoscope when used by anesthetists with limited and extensive experience in simulated Pierre Robin sequence. METHODS: Forty-three anesthetists with limited experience and forty-three anesthetists with extensive experience participated in our randomized crossover manikin trial. Each performed endotracheal intubation with the Glidescope® Core™ with a hyperangulated blade, the C-MAC® with a Miller blade and the conventional Miller laryngoscope. "Time to intubate" was the primary endpoint. Secondary endpoints were "time to vocal cords", "time to ventilate", overall success rate, number of intubation attempts and optimization maneuvers, Cormack-Lehane score, severity of dental trauma and subjective impressions. RESULTS: Both hyperangulated and nonangulated VLs provided superior intubation conditions. The Glidescope® Core™ enabled the best glottic view, caused the least dental trauma and significantly decreased the "time to vocal cords". However, the failure rate of intubation was 14% with the Glidescope® Core™, 4.7% with the Miller laryngoscope and only 2.3% with the C-MAC® Miller when used by anesthetists with extensive previous experience. In addition, the "time to intubate", the "time to ventilate" and the number of optimization maneuvers were significantly increased using the Glidescope® Core™. In the hands of anesthetists with limited previous experience, the failure rate was 11.6% with the Glidescope® Core™ and 7% with the Miller laryngoscope. Using the C-MAC® Miller, the overall success rate increased to 100%. No differences in the "time to intubate" or "time to ventilate" were observed. CONCLUSIONS: The nonangulated C-MAC® Miller facilitated correct placement of the endotracheal tube and showed the highest overall success rate. Our results therefore suggest that the C-MAC® Miller could be beneficial and may contribute to increased safety in the airway management of infants with PRS when used by anesthetists with limited and extensive experience.

The effect of laryngoscope types on hemodynamic response and optic nerve sheath diameter. McCoy, Macintosh, and C-MAC video-laryngoscope.

OBJECTIVES: This study aims to investigate the effect of McCoy, Macintosh laryngoscope, and C-MAC video-laryngoscopes on optic nerve sheath diameter (ONSD) and hemodynamic responses to laryngoscopy and intubation. METHODS: This prospective randomized study was conducted in Zonguldak Bülent Ecevit University Hospital, Zonguldak, Turkey, between July 2019 and January 2020. Informed written consent was obtained from all patients. Patients with previous intracranial/ocular surgery or glaucoma were excluded from the study. The patients were randomized to use McCoy, Macintosh, and C-MAC (30 per group). Intubations were performed by the same person. Mean arterial pressure, heart rate (HR), and ONSD were recorded before the induction and repeated in 1, 3, 5, and 10 minutes after the intubation. RESULTS: The effects of laryngoscopy and intubation on hemodynamic responses and ONSD were similar between groups (p greater than 0.05). While the comparison within groups showed ONSD increase in McCoy group and HR and ONSD increase in the Macintosh group compared to baseline 1 min after the intubation, no change was observed in hemodynamic responses and ONSD measurements in the C-MAC® group (p greater than 0.05). CONCLUSIONS: In this study, there was no significant difference between the groups in terms of ONSD and hemodynamic responses to laryngoscopy and intubation. It was observed that there were no significant changes in ONSD values just in C-MAC® video-laryngoscope group. Therefore, intubations with C-MAC® video-laryngoscope are thought to be more appropriate for patients with an increase in intracranial pressure.

Comparison of three video laryngoscopes and direct laryngoscopy for emergency endotracheal intubation: a retrospective cohort study.

OBJECTIVE: Video laryngoscopes are used for managing difficult airways. This study compared three video laryngoscopes' (Pentax-Airway Scope [Pentax], King Vision[King] and McGrath MAC [McGrath]) performances with the Macintosh direct laryngoscope (Macintosh) as emergency tracheal intubations (TIs) reference. DESIGN: Retrospective cohort study. SETTING: The emergency department (ED) and the intensive care unit (ICU) of two Japanese tertiary-level hospitals. PARTICIPANTS: All consecutive video-recorded emergency TI cases in EDs and ICUs between December 2013 and June 2015. PRIMARY OUTCOME MEASURES: The primary study endpoint was first-pass intubation success. A subgroup analysis examined the first-pass intubation success of expert versus non-expert operators. A logistic regression analysis was performed to identify the predictors of first-pass intubation success. RESULTS: A total of 287 emergency TIs were included. The first-pass intubation success rates were 78%, 58%, 78% and 58% for the Pentax, King, McGrath and Macintosh instruments, respectively (p=0.004, Fisher's exact test). The non-expert operators' success rates were significantly higher (p=0.00004, Fisher's exact test) for the Pentax (87%) and McGrath (78%) instruments than that for the King (50%) and Macintosh (46%) instruments, unlike that of the experts (67%, 67%, 78% and 78% for Pentax, McGrath, King and Macintosh, respectively; p=0.556, Fisher's exact test). After TI indication, difficult airway characteristics, and expert versus non-expert operator parameters adjustments, the Pentax (OR=3.422, 95% CI 1.551 to 7.550; p=0.002) and McGrath (OR= 3.758, CI 1.640 to 8.612; p=0.002) instruments showed significantly higher first-pass intubation success odds when compared with the Macintosh laryngoscope (reference, OR=1). The King instrument, however, (OR=1.056; 95% CI 0.487 to 2.289, p=0.889) failed to show any significant superiority. CONCLUSION: The Pentax and McGrath laryngoscopes showed significantly higher emergency TI first-pass intubation success rates than the King laryngoscope when compared with the Macintosh laryngoscope, especially for non-expert operators. TRIAL REGISTRATION NUMBER: UMIN000027925; Results.

Intubation performance using different laryngoscopes while wearing chemical protective equipment: a manikin study.

OBJECTIVES: This study aimed to compare visualisation of the vocal cords and performance of intubation by anaesthetists using four different laryngoscopes while wearing full chemical protective equipment. SETTING: Medical simulation center of a university hospital, department of anaesthesiology. PARTICIPANTS: 42 anaesthetists (15 females and 27 males) completed the trial. The participants were grouped according to their professional education as anaesthesiology residents with experience of <2 years or <5 years, or as anaesthesiology specialists with experience of >5 years. INTERVENTIONS: In a manikin scenario, participants performed endotracheal intubations with four different direct and indirect laryngoscopes (Macintosh (MAC), Airtraq (ATQ), Glidescope (GLS) and AP Advance (APA)), while wearing chemical protective gear, including a body suit, rubber gloves, a fire helmet and breathing apparatus. PRIMARY AND SECONDARY OUTCOME MEASURES: With respect to the manikin, setting time to complete 'endotracheal intubation' was defined as primary end point. Glottis visualisation (according to the Cormack-Lehane score (CLS) and impairments caused by the protective equipment, were defined as secondary outcome measures. RESULTS: The times to tracheal intubation were calculated using the MAC (31.4 s; 95% CI 26.6 to 36.8), ATQ (37.1 s; 95% CI 28.3 to 45.9), GLS (35.4 s; 95% CI 28.7 to 42.1) and APA (23.6 s; 95% CI 19.1 to 28.1), respectively. Intubation with the APA was significantly faster than with all the other devices examined among the total study population (p<0.05). A significant improvement in visualisation of the vocal cords was reported for the APA compared with the GLS. CONCLUSIONS: Despite the restrictions caused by the equipment, the anaesthetists intubated the manikin successfully within adequate time. The APA outperformed the other devices in the time to intubation, and it has been evaluated as an easily manageable device for anaesthetists with varying degrees of experience (low to high), providing good visualisation in scenarios that require the use of chemical protective equipment.

McGrath Video Laryngoscopy Facilitates Routine Nasotracheal Intubation in Patients Undergoing Oral and Maxillofacial Surgery: A Comparison With Macintosh Laryngoscopy.

PURPOSE: The McGrath video laryngoscope (VL) offers excellent laryngoscopic views and increases the success rate of orotracheal intubation in patients with normal and difficult airways. The purpose of this randomized controlled trial was to compare the McGrath VL with the Macintosh laryngoscope to investigate the efficacy of the McGrath VL for routine nasotracheal intubation in patients with an expected normal airway. MATERIALS AND METHODS: To address the research purpose, the efficacy of the McGrath VL for routine nasotracheal intubation was compared with that of the Macintosh laryngoscope. The predictor variable was the laryngoscopic technique (McGrath VL vs Macintosh laryngoscope). The outcome variables were the time to successful intubation, laryngoscopic views before and after optimal external laryngeal manipulation (OELM), use of Magill forceps, ease of intubation, and severity of oropharyngeal bleeding. RESULTS: Data from 35 patients undergoing oral and maxillofacial surgery were assessed. The time to intubation was 10.5 seconds shorter in the McGrath group than in the Macintosh group (34.4 ± 13.7 vs 44.9 ± 15.6 seconds; P = .004). The incidence of grade 1 glottic view before OELM was higher in the McGrath group than in the Macintosh group (83 vs 57%; P = .019). The frequency of Magill forceps use was lower in the McGrath group than in the Macintosh group (6 vs 34%; P = .003). CONCLUSION: McGrath VL facilitates routine nasotracheal intubation in expected normal airways by providing a shorter intubation time and better laryngoscopic views compared with the Macintosh laryngoscope.

Comparison of three types of laryngoscope for tracheal intubation during rhythmic chest compressions: a manikin study.

BACKGROUND: If tracheal intubation can be performed during uninterrupted chest compressions, this will sustain circulation during the procedure of intubation and may lead to successful resuscitation. We compared three types of laryngoscope on a manikin as to whether they enabled tracheal intubation while the manikin's chest was rhythmically compressed. METHODS: A total of 35 persons who had little or no experience in intubation served as examinees. The laryngoscopes employed were a conventional Macintosh laryngoscope (MAC), a new video laryngoscope, Pentax-AWS (AWS) and an optic laryngoscope Airtraq (ATQ). During chest compression on the manikin by an assistant, the examinee attempted to perform intubation. The success rate and the time for successful intubation were measured. RESULTS: During rhythmic chest compressions, nine examinees failed in tracheal intubation with the MAC, seven failed with the ATQ, and no one failed with the AWS. The success rates with the AWS were significantly higher than those with the MAC (P<0.01) or ATQ (P<0.05). The time needed for intubation was significantly shorter with the Pentax-AWS than with the others. CONCLUSIONS: These results suggest that the use of the Pentax-AWS enables tracheal intubation while the patient's chest is rhythmically compressed, and would more often lead to successful intubation, which in turn may lead to more successful resuscitation.

Acoustic changes related to laryngeal examination with a rigid telescope.

The influence on voice quality of the insertion of endoscopic equipment with tongue anchoring and head position requirements during endoscopic evaluation has not been fully investigated. The present study attempted to examine the influence of: (1) the presence of a rigid endoscope and tongue anchoring, and (2) the angle of position technique (70-degree and 90-degree) on participants' vocal output during sustained production of the vowel /i/. Five acoustic measurements including fundamental frequency (F0) values, percent jitter values, relative average perturbation of F0 shimmer, and noise-to-harmonic ratios were used to represent participants' voice quality. Results indicated that F0 values were significantly influenced by the angle of sitting position, while percent jitter values, relative average perturbation of F0, shimmer, and noise- to-harmonic ratios were affected by the presence of a rigid endoscope and tongue anchoring.

Synchronous airway lesions and associated anomalies in children with laryngomalacia evaluated with rigid endoscopy.

OBJECTIVE: To evaluate the prevalence of synchronous airway lesions (SALs) and associated anomalies in children with laryngomalacia requiring rigid endoscopic evaluation, the clinical significance of such lesions, and safety and outcome of selective rigid endoscopy. SETTING: National Children's Hospital. DESIGN AND METHOD: Retrospective analysis. The records of all children diagnosed with laryngomalacia who underwent rigid endoscopy were identified from the surgical database over a 4-year period. OUTCOME MEASURES: Age at presentation, signs and symptoms at time of presentation, presence of associated neurological and/or congenital anomalies (ANCAs), presence of synchronous airway lesions, need for surgical intervention, complications and time to resolution of symptoms were assessed. RESULTS: There were 26 children in the study. The mean age at presentation ranged from 0 to 10 months of age. One child (3.8%) required surgical intervention for severe isolated laryngomalacia. Seven children (26.9%) had at least one SAL identified. Of these, six (85.7%) were previously diagnosed on flexible fibreoptic laryngoscopy (FFL). Two of the seven children with SALs required surgical management of the SAL. Prematurity and ANCAs prolonged hospital stays in these children. However, the presence of SALs did not affect the length of hospital stay or the time to resolution of symptoms. Symptom resolved in all children by 3 years of age, whether or not SALs or ANCAs are present. There was no adverse outcome in the study group. CONCLUSION: Despite having indications for rigid endoscopy, many children with laryngomalacia do not have SALs, which even when present, are rarely clinically significant. SALs and ANCAs do not impact the time to symptom resolution. The current indications for rigid endoscopy in the evaluation of laryngomalacia are appropriate and safe.

The use of an anaesthetic simulator to assess single-use laryngoscopy equipment.

OBJECTIVE: To compare the view at simulated direct laryngoscopy obtained with a standard laryngoscope, with and without a disposable cover and a disposable laryngoscope blade. DESIGN: Randomized non-blinded comparison. SETTING: The high-fidelity human patient simulator at the Scottish Clinical Simulation Centre. PARTICIPANTS: Thirty-two anaesthetists with between 11 months and 25 years of experience. INTERVENTIONS: A randomized comparison of ease of laryngoscopy with each laryngoscope option for simulated easy and difficult laryngoscopy. MAIN OUTCOME MEASURES: The best grade achievable at laryngoscopy (Cormack and Lehane grade) for each laryngoscope, for both easy and difficult laryngoscopy. RESULTS: For the easy setting, 34% (P = 0.001) of anaesthetists graded laryngoscopy more difficult with the covered laryngoscope, and 22% (P = 0.008) with the disposable laryngoscope considered laryngoscopy more difficult than with the standard laryngoscope. For the difficult simulator setting, 69% (P < 0.001) found laryngoscopy more difficult with the covered laryngoscope and 69% (P < 0.001) with the disposable laryngoscope, when compared with the standard laryngoscope. There was no difference between the laryngoscopy grades for the covered and disposable laryngoscope for either easy (P = 0.21) or difficult (P = 0.87) simulation. CONCLUSIONS: Single-use equipment, as presently recommended for tonsillectomy surgery by the UK Department of Health, makes laryngoscopy more difficult for anaesthetists.

The feasibility of rigid stroboscopy in children.

OBJECTIVE: Voice disorders in children are common but ways of their analysis are limited. We conducted a prospective feasibility study of rigid stroboscopy in children. METHODS: All children referred for voice analysis during the years 2002-2003 were evaluated including subjective perception of voice, voice recording, flexible or rigid laryngoscopy and stroboscopy. Children were prepared by an explanation and visual demonstration. Local anesthesia was introduced through inhalation of Lidocaine (2%) solution prior to examination. Stroboscopy was performed either by a 70 degrees rigid laryngoscope or by a 3.0 mm fiberoptic-flexible endoscope. RESULTS: Forty-two children were analyzed. Rigid stroboscopy was feasible in 31 children of whom 7 were under 10 years of age. Short phonation time (7), gag reflex (6), impaired view due to high and posteriorly inclined epiglottis (4) were the main reasons of failure. CONCLUSIONS: Standard telescopic stroboscopy can be safely and effectively implemented in the majority of children over 10 years of age.

Laryngeal structure and function in the pediatric larynx: clinical applications.

This article presents an overview of the normal anatomy and physiology of the pediatric larynx, followed by some examples of pediatric voice disorders that were chosen to exemplify the alterations to the laryngeal anatomy and the subsequent modifications to laryngeal function. Vocal fold nodules are primarily reviewed due to their high incidence in the pediatric population. Three other disorders, including laryngeal hyperfunction, unilateral vocal fold paralysis, are discussed because of their more common occurrence and the uniqueness of their etiology and intervention, particularly for the case of bilateral abductor vocal fold paralysis.

Evaluating the effectiveness and efficiency of voice therapy using transnasal flexible laryngoscopy: a randomized controlled trial.

Transnasal flexible laryngoscopy (TFL) is an examination of laryngeal anatomy and physiology using continuous light. TFL is being used increasingly by voice pathologists in treatment but with little scientific evidence to support it. The purpose of this study was to evaluate the effectiveness and efficiency of TFL as a therapeutic tool. The study used a prospective randomized controlled trial. Fifty dysphonic subjects were recruited and randomly assigned to either a traditional treatment group or a TFL-assisted treatment group. The effectiveness of voice therapy in both treatment groups was measured with a package of voice outcome measures. Subjects in both treatment groups demonstrated statistically significant improvements after voice therapy (perceptual auditory rating of voice quality measurement p < 0.01; instrumental electroglottographic measurement p < 0.01; patient questionnaire measurement p < 0.01). The time taken to complete treatment in both groups was recorded. The average (median) time taken to complete voice therapy in the TFL-assisted treatment group was 2 hours less than in the traditional treatment group (p < 0.01). Voice therapy with TFL as a therapy tool was effective and more efficient than traditional voice therapy.

Pediatric laryngoscopes: design and application.

Examination of the upper aerodigestive tract for diagnosis and treatment has become more important in pediatric otolaryngology. Techniques of endoscopy have improved, anesthesia is safer, and there are many specialized laryngoscopes designed specifically for the small, sensitive airways of infants and children. Knowledge of the design advantages, specifications, and applications, including the use of telescopes and the operating microscope, will assist in selection of the appropriate laryngoscope for optimum exposure.