A comparison of the ease of tracheal intubation using a McGrath MAC(®) laryngoscope and a standard Macintosh laryngoscope

Routine Use of Videolaryngoscopy in Airway Management

Tracheal intubation is a fundamental facet of airway management, for which the importance of achieving success at the first attempt is well recognized. Failure to do so can lead to significant morbidity and mortality if there is inadequate patient oxygenation by alternate means. The evidence supporting the benefits of a videolaryngoscope in attaining this objective is now overwhelming (in adults). This has led to its increasing recognition in international airway management guidelines and its promotion from an occasional airway rescue tool to the first-choice device during routine airway management. However, usage in clinical practice does not currently reflect the increased worldwide availability that followed the upsurge in videolaryngoscope purchasing during the coronavirus disease 2019 pandemic. There are a number of obstacles to widespread adoption, including lack of adequate training, fears over de-skilling at direct laryngoscopy, equipment and cleaning costs, and concerns over the environmental impact, among others. It is now clear that in order for patients to benefit maximally from the technology and for airway managers to fully appreciate its role in everyday practice, proper training and education are necessary. Recent research evidence has addressed some existing barriers to default usage, and the emergence of techniques such as awake videolaryngoscopy and video-assisted flexible (bronchoscopic) intubation has also increased the scope of clinical application. Future studies will likely further confirm the superiority of videolaryngoscopy over direct laryngoscopy, therefore, it is incumbent upon all airway managers (and their teams) to gain expertise in videolaryngoscopy and to use it routinely in their everyday practice..

[Prehospital postcardiac-arrest-sedation and -care in the Federal Republic of Germany-a web-based survey of emergency physicians]

BACKGROUND

This study evaluates the implementation of postcardiac-arrest-sedation (PCAS) and -care (PRC) by prehospital emergency physicians in Germany.

MATERIALS AND METHODS

Analysis of a web-based survey from October to November 2022. Questions were asked about implementation, medications used, complications, motivation for implementing or not implementing PCAS, and measures and target parameters of PRC.

RESULTS

A total of 500 emergency physicians participated in the survey. In all, 73.4% stated that they regularly performed PCAS (hypnotics: 84.7%; analgesics: 71.1%; relaxants: 29.7%). Indications were pressing against the respirator (88.3%), analgesia (74.1%), synchronization to respirator (59.5%), and change of airway device (52.6%). Reasons for not performing PCAS (26.6%) included unconscious patients (73.7%); concern about hypotension (31.6%), re-arrest (26.3%), and worsening neurological assessment (22.5%). Complications of PCAS were observed by 19.3% of participants (acute hypotension [74.6%]); (re-arrest [32.4%]). In addition to baseline monitoring, PRC included 12-lead-electrocardiogram (96.6%); capnography (91.6%); catecholamine therapy (77.6%); focused echocardiography (20.6%), lung ultrasound (12.0%) and abdominal ultrasound (5.6%); induction of hypothermia (13.6%) and blood gas analysis (7.4%). An etCO2 of 35-45 mm Hg was targeted by 40.6%, while 9.0% of participants targeted an SpO2 of 94-98% and 19.2% of participants targeted a systolic blood pressure of ≥ 100 mm Hg.

CONCLUSIONS

Prehospital PRC in Germany is heterogeneous and deviations from its target parameters are frequent. PCAS is frequent and associated with relevant complications. The development of preclinical care algorithms for PCAS and PRC within preclinical care seems urgently needed.

Usefulness of video laryngoscopy in tracheal intubation at thyroid surgical position for intraoperative neuromonitoring

This observational study aimed to compare the glottic view between video and direct laryngoscopy for tracheal intubation in the surgical position for thyroid surgery with intraoperative neuromonitoring. Patients scheduled for elective thyroid surgery with intraoperative neuromonitoring were enrolled. After the induction of anesthesia, patients were positioned in the thyroid surgical posture with a standard inclined pillow under their head and back. An investigator assessed the glottic view using the percentage of glottic opening (POGO) scale and the modified Cormack-Lehane grade in direct laryngoscopy and then video laryngoscopy sequentially while using the same McGRATH™ MAC video laryngoscope at once, with or without external laryngeal manipulation, at the surgical position. A total of thirty-nine patients were participated in this study. Without external laryngeal manipulation, the POGO scale significantly improved during video laryngoscopy compared to direct laryngoscopy in the thyroid surgical position (60.0 ± 38.2% vs. 22.4 ± 23.8%; mean difference (MD) 37.6%, 95% confidence interval (CI) = [29.1, 46.0], P < 0.001). Additionally, with external laryngeal manipulation, the POGO scale showed a significant improvement during video laryngoscopy compared to direct laryngoscopy (84.6 ± 22.9% vs. 58.0 ± 36.3%; MD 26.7%, 95% CI = [18.4, 35.0] (P < 0.001). The superiority of video laryngoscopy was also observed for the modified Cormack-Lehane grade. In conclusion, video laryngoscopy with the McGRATH™ MAC video laryngoscope, when compared to direct laryngoscopy with it, improved the glottic view during tracheal intubation in the thyroid surgical position. This enhancement may potentially facilitate the proper placement of the electromyography tracheal tube and prevent tube displacement due to positional change for thyroid surgery.

Comparison of McGrath Videolaryngoscope versus Macintosh Laryngoscope in Tracheal Intubation: An Updated Systematic Review

(1) Background: In the last few years, many randomized controlled trials (RCTs) have compared direct Macintosh laryngoscopy with McGrath videolaryngoscopy in order to assess the potential benefits of the latter; the results were sometimes controversial. (2) Methods: We conducted a comprehensive literature search to identify our articles according to inclusion and exclusion criteria: to be included, each study had to be a prospective randomized trial or comparison between the McGrath videolaryngoscope and the Macintosh laryngoscope in an adult population. We did not include manikin trials or studies involving double-lumen tubes. (3) Results: 10 studies met the inclusion criteria necessary. In total, 655 patients were intubated with the McGrath and 629 with the Macintosh. In total, 1268 of 1284 patients were successfully intubated, showing equivalent results for the two devices: 648 of 655 patients with the McGrath videolaryngoscope and 620 of 629 patients with the Macintosh laryngoscope. No differences were noted in terms of hemodynamic changes or the incidence of adverse events. (4) Conclusions: We can assert that the McGrath videolaryngoscope and Macintosh laryngoscope, even if with equivalent tracheal intubation results, supplement each other.

Evaluation of free-floating tracheal intubation in weightlessness via ice-pick position with a direct laryngoscopy and classic approach with indirect videolaryngoscopy

Long duration spaceflights to the Moon or Mars are at risk for emergency medical events. Managing a hypoxemic distress and performing an advanced airway procedure such as oro-tracheal intubation may be complicated under weightlessness due to ergonomic constraints. An emergency free-floating intubation would be dangerous because of high failure rates due to stabilization issues that prohibits its implementation in a space environment. Nevertheless, we hypothesized that two configurations could lead to a high first-pass success score for intubation performed by a free-floating operator. In a non-randomized, controlled, cross-over simulation study during a parabolic flight campaign, we evaluated and compared the intubation performance of free-floating trained operators, using either a conventional direct laryngoscope in an ice-pick position or an indirect laryngoscopy with a video-laryngoscope in a classic position at the head of a high-fidelity simulation manikin, in weightlessness and in normogravity. Neither of the two tested conditions reached the minimal terrestrial ILCOR recommendations (95% first-pass success) and therefore could not be recommended for general implementation under weightlessness conditions. Free-floating video laryngoscopy at the head of the manikin had a significant better success score than conventional direct laryngoscopy in an ice-pick position. Our results, combined with the preexisting literature, emphasis the difficulties of performing oro-tracheal intubation, even for experts using modern airway devices, under postural instability in weightlessness. ClinicalTrials registration number NCT05303948.

Ease of Intubation with McGrath Videolaryngoscope and Incidence of Adverse Events During Tracheal Intubation in COVID-19 Patients: A Prospective Observational Study

Background

Tracheal intubation in critically ill patients remains high-risk despite advances in equipment, technique, and clinical guidelines. Many patients with COVID-19 were in respiratory distress and required intubation that is considered an aerosol-generating procedure (AGP). The transition to videolaryngoscopy as a routine first line option throughout anesthetic and ICU practice has been reported. We evaluated the ease of intubation, success rate, use of accessory maneuvers and adverse outcomes during and 24 hours after intubation with the McGrath videolaryngoscope.

Methods

This was a prospective, observational single center study conducted at non-operating room locations that included all adults (>18 years old) with suspected or confirmed COVID-19 infection and were intubated by McGrath videolaryngoscope. The anesthesiologist performed tracheal intubation were requested to fill online data collection form. A co-investigator was responsible to coordinate daily with assigned consultants for COVID intubation and follow up of patients at 24 hours after intubation.

Results

A total of 105 patients were included in our study. Patients were predominantly male (n=78; 74.3%), their COVID status was either confirmed (n=97, 92.4%) or suspected (n=8, 7.6%). Most were intubated in the COVID ward (n=59, 56.2%) or COVID ICU (n=23, 21.9%). The overall success rate of intubation with McGrath in the first attempt was 82.9%. The glottic view was either full (n=85, 80.95%), partial (n=16, 15.24%) or none (n=4, 3.81%). During intubation, hypoxemia occurred in 18.1% and hypotension in 16.2% patients. Within 24 hours of intubation, pneumothorax occurred in 1.9%, cardiac arrest and return of spontaneous circulation in 6.7% and mortality in 13.3% of patients.

Conclusion

These results illustrate the ease and utility of the McGrath videolaryngoscope for tracheal intubation in COVID-19 patients. Its disposable blade is of significant value in protectin during tracheal intubation.

The effect of head position on glottic visualization with video laryngoscope and intubation success in obese patients who are not expected to have a difficult airway: a prospective randomized clinical study

Intubation is required to maintain anesthesia in patients who are planned to undergo surgery under general anesthesia. One of the most important steps for successful intubation is to position head and neck appropriately. Sniffing position, head extension position, and neutral head position are the most known and used head and neck positions. The aim of this study is to examine the effect of head position on glottic visualization with McGrath MAC® video laryngoscope (VL) and intubation success in obese patients who are scheduled for surgery. A total of 150 patients, 50 patients in each group, with a body mass index of 30 and above were included in the study. The patients included in the study were divided into three groups: neutral head position, head extension position and sniffing position. During the intubation with McGrath MAC® VL, the groups were compared in terms of percent of glottic opening (POGO) score, intubation duration and Intubation Difficulty Scale (IDS) score. While the POGO score was found to be statistically significantly higher in the sniffing position than in the neutral head position (p < 0.001), it was similar in the extension position. The intubation duration was found to be statistically significantly shorter in the sniffing position than in the neutral head position (p = 0.001). However, there was no statistically significant difference between sniffing and extension positions. IDS score was found to be statistically significantly higher in the neutral head position compared to the other positions (p < 0.001, p < 0.001, respectively). In addition, the IDS score was statistically significantly higher in head extension position than in sniffing position (p = 0.016). This study is a randomized controlled trial of 150 patients investigating the impact of head position on glottic visualization and intubation success in obese patients when using Macintosh-like VL. The results show that sniffing position may be favored.

Videolaryngoscopy versus direct laryngoscopy for adults undergoing tracheal intubation

BACKGROUND

Tracheal intubation is a common procedure performed to secure the airway in adults undergoing surgery or those who are critically ill. Intubation is sometimes associated with difficulties and complications that may result in patient harm. While it is traditionally achieved by performing direct laryngoscopy, the past three decades have seen the advent of rigid indirect videolaryngoscopes (VLs). A mounting body of evidence comparing the two approaches to tracheal intubation has been acquired over this period of time. This is an update of a Cochrane Review first published in 2016.

OBJECTIVES

To assess whether use of different designs of VLs in adults requiring tracheal intubation reduces the failure rate compared with direct laryngoscopy, and assess the benefits and risks of these devices in selected population groups, users and settings.

SEARCH METHODS

We searched MEDLINE, Embase, CENTRAL and Web of Science on 27 February 2021. We also searched clinical trials databases, conference proceedings and conducted forward and backward citation searches.

SELECTION CRITERIA

We included randomized controlled trials (RCTs) and quasi-RCTs with adults undergoing laryngoscopy performed with either a VL or a Macintosh direct laryngoscope (DL) in any clinical setting. We included parallel and cross-over study designs.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by Cochrane. We collected data for the following outcomes: failed intubation, hypoxaemia, successful first attempt at tracheal intubation, oesophageal intubation, dental trauma, Cormack-Lehane grade, and time for tracheal intubation.

MAIN RESULTS

We included 222 studies (219 RCTs, three quasi-RCTs) with 26,149 participants undergoing tracheal intubation. Most studies recruited adults undergoing elective surgery requiring tracheal intubation. Twenty-one studies recruited participants with a known or predicted difficult airway, and an additional 25 studies simulated a difficult airway. Twenty-one studies were conducted outside the operating theatre environment; of these, six were in the prehospital setting, seven in the emergency department and eight in the intensive care unit.  We report here the findings of the three main comparisons according to videolaryngoscopy device type. We downgraded the certainty of the outcomes for imprecision, study limitations (e.g. high or unclear risks of bias), inconsistency when we noted substantial levels of statistical heterogeneity and publication bias. Macintosh-style videolaryngoscopy versus direct laryngoscopy (61 studies, 9883 participants) We found moderate-certainty evidence that a Macintosh-style VL probably reduces rates of failed intubation (risk ratio (RR) 0.41, 95% confidence interval (CI) 0.26 to 0.65; 41 studies, 4615 participants) and hypoxaemia (RR 0.72, 95% CI 0.52 to 0.99; 16 studies, 2127 participants). These devices may also increase rates of success on the first intubation attempt (RR 1.05, 95% CI 1.02 to 1.09; 42 studies, 7311 participants; low-certainty evidence) and probably improve glottic view when assessed as Cormack-Lehane grade 3 and 4 (RR 0.38, 95% CI 0.29 to 0.48; 38 studies, 4368 participants; moderate-certainty evidence). We found little or no clear difference in rates of oesophageal intubation (RR 0.51, 95% CI 0.22 to 1.21; 14 studies, 2404 participants) but this finding was supported by low-certainty evidence. We were unsure of the findings for dental trauma because the certainty of this evidence was very low (RR 0.68, 95% CI 0.16 to 2.89; 18 studies, 2297 participants). We were not able to pool data for time required for tracheal intubation owing to considerable heterogeneity (I2 = 96%). Hyperangulated videolaryngoscopy versus direct laryngoscopy (96 studies, 11,438 participants) We found moderate-certainty evidence that hyperangulated VLs probably reduce rates of failed intubation (RR 0.51, 95% CI 0.34 to 0.76; 63 studies, 7146 participants) and oesophageal intubation (RR 0.39, 95% CI 0.18 to 0.81; 14 studies, 1968 participants). In subgroup analysis, we noted that hyperangulated VLs were more likely to reduce failed intubation when used on known or predicted difficult airways (RR 0.29, 95% CI 0.17 to 0.48; P = 0.03 for subgroup differences; 15 studies, 1520 participants). We also found that these devices may increase rates of success on the first intubation attempt (RR 1.03, 95% CI 1.00 to 1.05; 66 studies, 8086 participants; low-certainty evidence) and the glottic view is probably also improved (RR 0.15, 95% CI 0.10 to 0.24; 54 studies, 6058 participants; data for Cormack-Lehane grade 3/4 views; moderate-certainty evidence). However, we found low-certainty evidence of little or no clear difference in rates of hypoxaemia (RR 0.49, 95% CI 0.22 to 1.11; 15 studies, 1691 participants), and the findings for dental trauma were unclear because the certainty of this evidence was very low (RR 0.51, 95% CI 0.16 to 1.59; 30 studies, 3497 participants). We were not able to pool data for time required for tracheal intubation owing to considerable heterogeneity (I2 = 99%). Channelled videolaryngoscopy versus direct laryngoscopy (73 studies, 7165 participants) We found moderate-certainty evidence that channelled VLs probably reduce rates of failed intubation (RR 0.43, 95% CI 0.30 to 0.61; 53 studies, 5367 participants) and hypoxaemia (RR 0.25, 95% CI 0.12 to 0.50; 15 studies, 1966 participants). They may also increase rates of success on the first intubation attempt (RR 1.10, 95% CI 1.05 to 1.15; 47 studies, 5210 participants; very low-certainty evidence) and probably improve glottic view (RR 0.14, 95% CI 0.09 to 0.21; 40 studies, 3955 participants; data for Cormack-Lehane grade 3/4 views; moderate-certainty evidence). We found little or no clear difference in rates of oesophageal intubation (RR 0.54, 95% CI 0.17 to 1.75; 16 studies, 1756 participants) but this was supported by low-certainty evidence. We were unsure of the findings for dental trauma because the certainty of the evidence was very low (RR 0.52, 95% CI 0.13 to 2.12; 29 studies, 2375 participants). We were not able to pool data for time required for tracheal intubation owing to considerable heterogeneity (I2 = 98%).

AUTHORS' CONCLUSIONS

VLs of all designs likely reduce rates of failed intubation and result in higher rates of successful intubation on the first attempt with improved glottic views. Macintosh-style and channelled VLs likely reduce rates of hypoxaemic events, while hyperangulated VLs probably reduce rates of oesophageal intubation. We conclude that videolaryngoscopy likely provides a safer risk profile compared to direct laryngoscopy for all adults undergoing tracheal intubation.

Video screen visualization patterns when using a video laryngoscope for tracheal intubation: A systematic review

OBJECTIVE

Published studies of video laryngoscopes are often limited by the lack of a clear definition of video laryngoscopy (VL). We performed a systematic review to determine how often published studies of VL report on video screen visualization.

METHODS

We searched PubMed, EMBASE and Scopus for interventional and observational studies in which a video laryngoscope equipped with a standard geometry blade was used for tracheal intubation. We excluded simulation based studies. Our primary outcome was data on video laryngoscope screen visualization. Secondary outcomes were explicit methodology for screen visualization.

RESULTS

We screened 4838 unique studies and included 207 (120 interventional and 87 observational). Only 21 studies (10% of 207) included any data on video screen visualization by the proceduralist, 19 in a yes/no fashion only (ie, screened viewed or not) and 2 with detail beyond whether the screen was viewed or not. In 11 more studies, visualization patterns could be inferred based on screen availability and in 16 more studies, the methods section stated how screen visualization was expected to be performed without reporting data collection on how the proceduralist interacted with the video screen. Risk of bias was high in the majority of included studies.

CONCLUSIONS

Published studies of VL, including many clinical trials, rarely include data on video screen visualization. Given the nuances of using a video laryngoscope, this is a critical deficiency, which largely prevents us from knowing the treatment effect of using a video laryngoscope in clinical practice. Future studies of VL must address this deficiency.

Comparison of the intubation success rate between the intubating catheter and videolaryngoscope in difficult airways: a prospective randomized trial

BACKGROUND

Several devices and algorithms have already been examined and compared for difficult airway management. However, there is no existing study comparing the success of the Intubating Catheter (IC) and the Videolaryngoscope (VL) in patients who are difficult to intubate. We aimed to compare Frova IC and McGrath VL in terms of intubation success rates in patients with difficult intubation.

METHODS

This prospective, randomized study was performed in an university hospital. Patients who underwent an operation under general anesthesia and whom airway management process was deemed difficult were included in this study. Patients were randomly divided into two groups by envelopes containing a number: the intubating catheter group (Group IC), intubated using the Frova IC, and the videolaryngoscope group (Group VL), intubated using the McGrath VL. Study data were collected by a technician who was blind to the study groups and the type of device used in the intubation procedure.

RESULTS

A total of 49 patients with difficult airway were included in the study, including 25 patients in the Frova IC Group and 24 patients in the McGrath VL Group. The rate of successful intubation was determined to be 88% in Group IC and 66% in Group VL (p = 0.074). The mean duration of intubation attempt in Group VL was 44.62 seconds, whereas in Group IC, it was 51.12 seconds (p = 0.593). Group VL was found to have a significantly lower Cormack-Lehane grade compared to Group IC (p < 0.001).

CONCLUSION

Frova IC is a candidate to be an indispensable instrument in terms of cost-effectiveness in clinics such as anesthesia and emergency medicine, where difficult intubation cases are frequently encountered. However, the combination of Frova IC and McGrath VL seems to be more successful in difficult intubation situations, so future studies should focus on using these two devices together.

Comparison of the effects of the McGRATH MAC, C-MAC, and Macintosh laryngoscopes on the intraocular pressures of non-ophthalmic patients: A prospective, randomised, clinical trial

INTRODUCTION

In this prospective, randomised study, we compared the effects of the Macintosh, McGRATH MAC, and C-MAC laryngoscopes on intraocular pressure (IOP) and haemodynamics of non-ophthalmic patients during endotracheal intubation.

METHODS

One hundred and twenty adult patients undergoing non-ophthalmic surgeries performed in the supine position under general anaesthesia requiring orotracheal intubation were included in this study. The patients were separated randomly and prospectively into 3 groups: Macintosh group (n = 40), McGRATH MAC group (n = 40), and C-MAC group (n = 40). Mean arterial pressure (MAP), heart rate (HR) and IOP of left and right eye were measured at specified times.

RESULTS

There were no significant differences with regard to patients characteristics. After intubation, the HR increased significantly in the Macintosh group when compared to the other groups (p = 0.001) and the MAP increased significantly in the Macintosh group when compared to the McGRATH MAC group (p = 0.001) and the C-MAC group (p < 0.001). The IOP values increased in the Macintosh group when compared to the McGRATH MAC group (p < 0.001) and the C-MAC group (p < 0.001) after intubation. Additionally, there was a significant difference between the McGRATH MAC group and C-MAC group in the IOP values of the eyes after intubation (p < 0.001). According to the evaluation within the groups, there were significant differences in all of the groups at all times when compared with the baseline values (p < 0.001).

CONCLUSIONS

In this study, we concluded that the C-MAC VL may be preferable when compared to the Macintosh and McGRATH MAC laryngoscopes for use in ophthalmic patients in whom a rise in the IOP is undesirable.

Efficacy of stylet angulation at the holding position during tracheal intubation with a videolaryngoscope: a randomized controlled trial

The aim of this randomized controlled trial was to determine the efficacy of stylet angulation at the holding position during tracheal intubation with a McGRATH MAC videolaryngoscope. Patients were randomized to a group for intubation without stylet angulation at the holding position (non-angulation group) and to a group for intubation with stylet angulation at the holding position (angulation group). The primary outcome was the time for placement of the tracheal tube. Sixty patients were analyzed. The mean (standard deviation) times for tube placement were 21.3 (5.6) s in the non-angulation group and 16.9 (3.8) s in the angulation group (P < 0.001). The scores of operator's perception of difficulty in tube delivery, number of attempts for tube delivery, and degrees of extension, abduction, internal rotation of the right upper arm and extension of the right wrist during tube placement in the angulation group were significantly smaller than those in the non-angulation group (P < 0.001, P = 0.002, P < 0.001, P < 0.001, P < 0.001, P < 0.001, respectively). Our results suggest that stylet angulation at the holding position improves maneuverability of the tracheal tube and enables easy, smooth, and swift tube placement during tracheal intubation with a McGRATH MAC videolaryngoscope.

Comparison of learning direct laryngoscopy using a McGrath videolaryngoscope as a direct versus indirect laryngoscope: a randomized controlled trial

OBJECTIVE

Tracheal intubation using a direct laryngoscope is difficult to teach. The McGrath videolaryngoscope, a Macintosh-like device with a camera, can be used as a direct laryngoscope to educate novices under supervision using the screen. We compared the effect on Macintosh laryngoscopy skills following training with a McGrath videolaryngoscope as a direct versus indirect laryngoscope.

METHODS

Thirty-seven participants were randomized into direct and indirect groups according to the training method using a McGrath videolaryngoscope. Participants attempted Macintosh direct laryngoscopy in normal and difficult airway scenarios. The primary endpoint was the intubation time, and the rate of successful intubation, dental trauma, and difficulty were secondary outcomes.

RESULTS

The intubation time after education decreased significantly in both groups and was significantly shorter in the direct group than in the indirect group across time. The difficulty degree in the direct group was lower than that in the indirect group across time; however, the rate of dental trauma was not significantly different.

CONCLUSION

Both direct and indirect laryngoscopy using a McGrath videolaryngoscope improved the performance of Macintosh direct laryngoscopy in novices, while direct laryngoscopy using a McGrath videolaryngoscope demonstrated better educational effects than indirect laryngoscopy.Registered at ClinicalTrials.gov (NCT03471975).

The impact of a barrier enclosure on time to tracheal intubation: a randomized controlled trial

Purpose

Novel devices such as the barrier enclosure were developed in hopes of improving provider safety by limiting SARS-CoV-2 transmission during tracheal intubation. Nevertheless, concerns arose regarding a lack of rigorous efficacy and safety data for these devices. We conducted a randomized controlled trial to evaluate the impact of the barrier enclosure on time to tracheal intubation.

Method

After Research Ethics Board approval, elective surgical patients with normal airway predictors were randomly allocated 1:1 to tracheal intubation with or without a barrier enclosure. The primary outcome was time to tracheal intubation. Secondary outcomes included first-pass success rate, total time of airway manipulation, anesthesiologists’ perception of intubation difficulty, likelihood of use in SARS-CoV-2-positive patients, and patients’ perception of comfort and acceptability.

Results

There were 48 participants in the barrier enclosure group and 46 participants in the control group. The mean (standard deviation [SD]) time to tracheal intubation was 62 (29) sec with barrier closure and 53 (27) sec without barrier enclosure (mean difference, 9 sec; 95% confidence interval, − 3 to 20; P = 0.14). Anesthesiologists rated the difficulty of intubation higher with barrier enclosure (mean [SD] visual analogue scale score, 27 [26] mm vs 9 [17] mm; P < 0.001). There were no significant differences in other secondary outcomes.

Conclusion

In healthy surgical patients with normal airway predictors, the use of a barrier enclosure during tracheal intubation did not significantly prolong time to intubation or decrease first-pass intubation success. Nevertheless, there was an increase in difficulty of intubation perceived by the anesthesiologists with use of a barrier enclosure.

Trial registration

www.clinicaltrials.gov (NCT04366141); registered 28 April 2020.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12630-021-02024-z.

HELP-VDL: study protocol for a multicentre, open, randomised, controlled clinical trial comparing the use of the head-elevated laryngoscopy position and the use of a videolaryngoscope to facilitate orotracheal intubation in a patient population without predictable difficulty of intubation

INTRODUCTION

Tracheal intubation remains an everyday challenge for anaesthesiologists, even in patients without suspected difficult airways. The ideal positioning of the patient's head (flat, raised a few centimetres on a cushion in the sniffing position (SP), or raised to achieve horizontal alignment between the external acoustic meatus and the sternal angle) and the use of videolaryngoscopy remain controversial. This trial aims to compare the efficacy for orotracheal intubation of the SP or the head-elevated laryngoscopy position (HELP), which has been shown to improve laryngeal visualization and the intubation condition particularly in obese patients, in combination with a McGrath Mac videolaryngoscope whose video screen is either on or off (Video or NoVideo).

METHODS AND ANALYSIS

The HELP-VDL factorial trial is a prospective, randomised, parallel, multicentre, open study of 240 adult patients undergoing tracheal intubation under general anaesthesia. Patients will be allocated into four groups: SP-NoVideo, HELP-NoVideo, SP-Video and HELP-Video. The primary outcome is the proportion of orotracheal intubations that requires the assistance of a nurse anaesthetist. The secondary outcomes include the intubation duration, the first intubation success rate, the quality of visualisation of the glottis, the glottis visualisation score, adjunctive manoeuvres and alternative techniques used, the occurrence of oesophageal intubation, failure of tracheal intubation, the incidence of arterial oxygen desaturation, the perception of a difficult intubation, the score on the Intubation Difficulty Scale, cooperation among the members of the anaesthesia team, the evolution of vital signs and the frequency and severity of intubation complications. Data will be analysed on the intention-to-treat principle and a per-protocol basis.

ETHICS AND DISSEMINATION

Ethics approval was obtained from the Ethical Committee Ile de France V (Paris, France). Participant recruitment began on 3 July 2019. The results will be submitted for publication in peer-reviewed journals.Trial registration numberNCT03987009; Pre-results.

Recent advances in laryngoscopy in adults

Recent advances in technology have made laryngoscopy less dependent upon a direct line of sight to achieve tracheal intubation. Whether these new devices are useful tools capable of increasing patient safety depends upon when and how they are used. We briefly consider the challenges in reviewing the emerging literature given the variety of devices, "experience" of the care providers, the clinical settings, and the definitions of outcome. We examine some of the limitations of conventional direct laryngoscopy, question the definitions we have used to define success, discuss the benefits of indirect (video) techniques, and review evidence pertaining to their use in the patients in the operating room, emergency department, and intensive care unit.

A single-centre, randomised controlled feasibility pilot trial comparing performance of direct laryngoscopy versus videolaryngoscopy for endotracheal intubation in surgical patients

Introduction

Most trials comparing effectiveness of laryngoscopy technique use surrogate endpoints. Intubation success is a more appropriate endpoint for comparing effectiveness of techniques or devices. A large pragmatic clinical trial powered for intubation success has not yet been performed.

Methods

We tested the feasibility of a randomised controlled trial to compare the performance of direct laryngoscopy versus videolaryngoscopy for endotracheal intubation. The trial was conducted in the Department of Adult and Emergency Anaesthesia at the Auckland City Hospital, New Zealand. Patients over 18 years who required endotracheal intubation and were not known or predicted to be difficult to bag-mask ventilate were eligible for the study. Patients were excluded if they required rapid sequence induction, fibreoptic intubation or were unable to consent due to language barriers or cognitive impairment.

Patients were permuted block randomised in groups of 8 to either direct laryngoscopy (DL) or videolaryngoscopy (VL) for the technique of endotracheal intubation. Patients were blinded to laryngoscopic technique; the duty anaesthetist, outcome assessors and statistician were unblinded.

Feasibility was assessed on recruitment rate, adherence to group assignment and data completeness. Primary outcome was first-pass success rate, with secondary outcomes of time to intubation (seconds), Intubation Difficulty Score and complication rate.

Results

One hundred and six patients were randomised and 100 patient results were analysed. Completed data from patients randomised to the DL group (n = 49) was compared with those in the VL group (n = 51). Group adherence and data completeness were 100% and 97%, respectively. First-pass success rate was 83.7% in the direct laryngoscopy group and 72.5% in the videolaryngoscopy group (p = 0.18). Median time to intubation was significantly shorter for direct laryngoscopy when compared to videolaryngoscopy (34 s v 43 s, p = 0.038). Complications included mucosal trauma and airway bleeding which are recognised complications of endotracheal intubation.

Conclusion

A large, pragmatic, multicentre, randomised controlled trial comparing the relative effectiveness of direct laryngoscopy and indirect videolaryngoscopy is feasible.

Trial registration

Australian New Zealand Clinical Trials Registry (ANZCTR), ACTRN12615001267549

Prospective Trial to Compare Direct and Indirect Laryngoscopy Using C-MAC PM® with Macintosh Blade and D-Blade® in a Simulated Difficult Airway

Objective. Evaluation of C-MAC PM® in combination with a standard Macintosh blade size 3 in direct and indirect laryngoscopy and D-Blade® in indirect laryngoscopy in a simulated difficult airway. Primary outcome was defined as the best view of the glottic structures. Secondary endpoints were subjective evaluation and assessment of the intubation process. Methods. Prospective monocentric, observational study on 48 adult patients without predictors for difficult laryngoscopy/tracheal intubation undergoing orthopedic surgery. Every participant preoperatively received a cervical collar to simulate a difficult airway. Direct and indirect laryngoscopy w/o the BURP maneuver with a standard Macintosh blade and indirect laryngoscopy w/o the BURP maneuver using D-Blade® were performed to evaluate if blade geometry and the BURP maneuver improve the glottic view as measured by the Cormack-Lehane score. Results. Using a C-MAC PM® laryngoscope, D-Blade® yielded improved glottic views compared with the Macintosh blade used with either the direct or indirect technique. Changing from direct laryngoscopy using a Macintosh blade to indirect videolaryngoscopy using C-MAC PM® with D-Blade® improved the Cormack-Lehane score from IIb, III, or IV to I or II in 31 cases. Conclusion. The combination of C-MAC PM® and D-Blade® significantly enhances the view of the glottis compared to direct laryngoscopy with a Macintosh blade in patients with a simulated difficult airway. Trial Registration Number. This trial is registered under number NCT03403946.

McGrath videolaryngoscope versus Macintosh laryngoscope for tracheal intubation: A systematic review and meta-analysis with trial sequential analysis

STUDY OBJECTIVE

The McGrath laryngoscope is a novel self-contained videolaryngoscope with a single-use blade. There are several anecdotal reports that the McGrath is superior to the Macintosh laryngoscope for tracheal intubation. However this remains controversial.

DESIGN

Meta-analysis and systematic review.

SETTING

Operating room or intensive care unit.

MEASUREMENTS

A comprehensive literature search was conducted to identify clinical trials that met our inclusion criteria. To qualify, studies had to be prospective randomized trials comparing tracheal intubation between the McGrath and the Macintosh in an adult population. We extracted data on success rate, glottic visualization during intubation, and intubation time from the studies identified. In subgroup analysis, we assessed the influence on each of these parameters which included airway condition (normal or difficult) and operator (novice or experienced). We then conducted a trial sequential analysis (TSA).

MAIN RESULTS

Fourteen articles met our inclusion criteria. The McGrath offered better glottic visualization than the Macintosh (risk ratio, 1.34; 95% confidence interval (CI), 1.25-1.45). However, the McGrath required longer intubation time (mean difference, 10.1s; CI, 2.74-17.5) and demonstrated similar success rate of tracheal intubation (risk ratio, 1.00; CI, 0.95-1.05) compared to the Macintosh. TSA showed that total sample size reached the required information size (RIS) in glottic visualization and success rate. However, only 15.1% of the RIS was achieved in intubation time. In the subgroup analysis for airway condition and operator experience level, there were no subgroup differences in both glottic visualization and intubation time.

CONCLUSIONS

Our meta-analysis suggests that the McGrath is superior to the Macintosh in terms of glottic visualization (GRADE: moderate). However, it significantly extends intubation time (GRADE: very low) and its success rate (GRADE: very low) for tracheal intubation is not excellent. TSA suggests that further studies are necessary to confirm the results of intubation time.

A comparison between McGrath MAC videolaryngoscopy and Macintosh laryngoscopy in children

BACKGROUND

This prospective, randomised, controlled study was performed to evaluate the usefulness of the McGrath VL compared with Macintosh laryngoscopy in children with expected normal airway during endotracheal intubation, by comparing the time to intubation and difficulty of intubation.

METHODS

Eighty-four patients aged 1-10 years who underwent endotracheal intubation for elective surgery were randomly assigned to the McGrath group (n = 42) or the Macintosh group (n = 42). Anaesthesia was induced with 2.5-3.0 mg/kg of propofol and sevoflurane 5-8 vol%. Orotracheal intubation was performed 2 min after injection of rocuronium 0.6 mg/kg with McGrath VL or Macintosh laryngoscope; the primary outcome was the time to intubation. The Cormack and Lehane glottic grade, intubation difficulty score (IDS), and success rate on intubation were assessed. Haemodynamic changes were also recorded.

RESULTS

As the primary outcome, median time to intubation [interquartile range] did not differ between the McGrath group and the Macintosh group (25.0 [22.8-28.3] s vs. 26.0 [24.0-29.0] s, P = 0.301). The incidence of grade I glottic view was significantly higher in the McGrath group than in the Macintosh group (95% vs. 74%, P = 0.013). Median IDS was lower in the McGrath group than in the Macintosh group (0 [0-0] vs. 0 [0-1], P = 0.018). There were no significant differences in success rate on intubation or haemodynamics between the two groups.

CONCLUSIONS

McGrath VL provides better laryngeal views and lower IDS but similar intubation times and success rates compared with the Macintosh laryngoscope in children with normal airway.

[Comparison of safe duration of apnea and intubation time in face mask ventilation with air versus 100% oxygen during induction of general anesthesia]

OBJECTIVE

To compare the safe duration of apnea and intubation time between face mask ventilation with air and 100% oxygen during induction of general anesthesia.

METHODS

Eighty adult patients with ASA class I or II without predicted difficult airways were scheduled for elective surgery under general anesthesia. The patients were randomized to receive anesthesia induction with preoxygenation [Group 1, n=40, fraction of inspired oxygen (FiO₂)=1] or without preoxygenation (Group2, n=40, FiO₂=0.21). Two experienced anesthesiologists performed the mask ventilation and tracheal intubation during induction, and the assistants adjusted the oxygen concentration and recorded the pulse oxygen saturation (SpO₂) and other variables. The cases where SpO₂ decreased to below 90% before accomplishment of intubation were considered unsuccessful, and mask ventilation with 100% oxygen was given. After tracheal intubation, mechanical ventilation was not initiated until the SpO₂ decreased to 90%. The number of unsuccessful cases, the safe duration of apnea and intubation time were recorded in the two groups.

RESULTS

There was no unsuccessful case in either groups. The safe duration of apnea was 469.5∓143.0 s in Group 1 and 63.6∓20.0 s in Group 2, and the intubation time was 34.4∓12.6 s and 32.8∓9.6 s, respectively. The safe duration of apnea was significantly longer than the intubation time in both groups (P<0.01). The intubation time and the number of cases with SpO₂≥90% before completion of tracheal intubation were similar between the two groups. The safe duration of apnea was significantly shorter in Group 2 than in Group 1 (P<0.01) and was correlated with the body mass index of the patients (P<0.05).

CONCLUSION

Anesthesia induction without preoxygenation can provide sufficient time for experienced anesthesiologists to complete tracheal intubation.

Guidelines for the management of tracheal intubation in critically ill adults

These guidelines describe a comprehensive strategy to optimize oxygenation, airway management, and tracheal intubation in critically ill patients, in all hospital locations. They are a direct response to the 4^th National Audit Project of the Royal College of Anaesthetists and Difficult Airway Society, which highlighted deficient management of these extremely vulnerable patients leading to major complications and avoidable deaths. They are founded on robust evidence where available, supplemented by expert consensus opinion where it is not. These guidelines recognize that improved outcomes of emergency airway management require closer attention to human factors, rather than simply introduction of new devices or improved technical proficiency. They stress the role of the airway team, a shared mental model, planning, and communication throughout airway management. The primacy of oxygenation including pre- and peroxygenation is emphasized. A modified rapid sequence approach is recommended. Optimal management is presented in an algorithm that combines Plans B and C, incorporating elements of the Vortex approach. To avoid delays and task fixation, the importance of limiting procedural attempts, promptly recognizing failure, and transitioning to the next algorithm step are emphasized. The guidelines recommend early use of a videolaryngoscope, with a screen visible to all, and second generation supraglottic airways for airway rescue. Recommendations for emergency front of neck airway are for a scalpel-bougie-tube technique while acknowledging the value of other techniques performed by trained experts. As most critical care airway catastrophes occur after intubation, from dislodged or blocked tubes, essential methods to avoid these complications are also emphasized.

Evaluation of the McGrath MAC and Macintosh laryngoscope for tracheal intubation in 2000 patients undergoing general anaesthesia: the randomised multicentre EMMA trial study protocol

INTRODUCTION

The direct laryngoscopy technique using a Macintosh blade is the first choice globally for most anaesthetists. In case of an unanticipated difficult airway, the complication rate increases with the number of intubation attempts. Recently, McGrath MAC (McGrath) video laryngoscopy has become a widely accepted method for securing an airway by tracheal intubation because it allows the visualisation of the glottis without a direct line of sight. Several studies and case reports have highlighted the benefit of the video laryngoscope in the visualisation of the glottis and found it to be superior in difficult intubation situations. The aim of this study was to compare the first-pass intubation success rate using the (McGrath) video laryngoscope compared with conventional direct laryngoscopy in surgical patients.

METHODS AND ANALYSIS

The EMMA trial is a multicentre, open-label, patient-blinded, randomised controlled trial. Consecutive patients requiring tracheal intubation are randomly allocated to either the McGrath video laryngoscope or direct laryngoscopy using the Macintosh laryngoscope. The expected rate of successful first-pass intubation is 95% in the McGrath group and 90% in the Macintosh group. Each group must include a total of 1000 patients to achieve 96% power for detecting a difference at the 5% significance level. Successful intubation with the first attempt is the primary endpoint. The secondary endpoints are the time to intubation, attempts for successful intubation, the necessity of alternatives, visualisation of the glottis using the Cormack & Lehane score and percentage of glottic opening score and definite complications.

ETHICS AND DISSEMINATION

The project was approved by the local ethics committee of the Medical Association of the Rhineland Palatine state and Westphalia-Lippe. The results of this study will be made available in the form of manuscripts for publication and presentations at national and international meetings.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov NCT 02611986; pre-results.

Stylet angulation for routine endotracheal intubation with McGrath videolaryngoscope

BACKGROUND

The McGrath videolaryngoscope (VL) provides excellent laryngoscopic views, but directing an endotracheal tube can be difficult, and thus the routine use of a stylet is recommended. The goal of this study is to determine the appropriate angle (60° vs 90°) of the stylet when using the McGrath VL by comparing the time to intubation (TTI).

METHODS

One hundred and forty patients aged 19 to 70 years (American Society of Anesthesiologists classification I or II) who required tracheal intubation for elective surgery were randomly allocated to 1 of 2 groups, at the 60° angle (n = 70) or the 90° angle (n = 70). Anesthesia was induced with propofol, fentanyl, and rocuronium. The primary outcome was TTI assessed by a blind observer. Glottic grade, use of optimal external laryngeal manipulation, failed intubation at first attempt, ease of intubation, and severity of oropharyngeal bleeding were also recorded.

RESULTS

The mean TTI was significantly shorter in the 60° group than in the 90° group (29.3 ± 6.4 vs 32.5 ± 9.4 s, P = 0.022). The glottic grade and degree of intubation difficulty were not significantly different between the 2 groups.

CONCLUSIONS

When intubating the patients with the McGrath videolaryngoscope, the 60° angled stylet allowed for faster orotracheal intubation than did the 90° angled stylet.

Evaluation of the McGrath® MAC videolaryngoscope in a tertiary teaching hospital

Background:

Videolaryngoscopes have become increasingly popular in recent years for use in both normal and difficult airways. Despite this trend, their benefit remains controversial. The McGrath® MAC videolaryngoscope (Aircraft Medical Ltd, Edinburgh, UK) is used for first line or rescue intubation, and for training in videolaryngoscopy intubation. We conducted a prospective observational study to assess the performance of the McGrath® MAC.

Methods:

We evaluated the use of the McGrath® MAC videolaryngoscope from January 2016 to April 2016. We recruited 500 adult patients undergoing elective surgery requiring endotracheal intubation. Data was collected via an online survey. The primary outcome was the success of intubation with the McGrath® MAC. Secondary outcomes included the ease of the McGrath® MAC insertion, best glottic view, ease of tracheal tube insertion, number of intubation attempts, evidence of airway trauma, quality of view, adjunct used, airway manoeuvres used, quality of image on monitor screen and overall impression of the device.

Results:

A total of 428 responses were analysed. The overall success rate was 97.9% (95% confidence interval 96.0–99.0%). The success rate for those with predictors of difficult airway was 95.5% (95% confidence interval 87.6–99.5%). Easy scope insertion was reported by 97.2% of anaesthetists and 89.7% reported easy tube insertion. Some of our cases (1.9%) were complicated by airway trauma involving superficial oropharyngeal or lip injury.

Conclusion:

The McGrath® MAC videolaryngoscope is a good choice for a videolaryngoscope, conferring advantages of a high intubation success rate, ease of laryngoscope insertion and ease of intubation. It is suitable for use in predicted difficult airways.

Videolaryngoscopy versus direct laryngoscopy for adult patients requiring tracheal intubation

BACKGROUND

Successful tracheal intubation during general anaesthesia traditionally requires a line of sight to the larynx attained by positioning the head and neck and using a laryngoscope to retract the tongue and soft tissues of the floor of the mouth. Difficulties with intubation commonly arise, and alternative laryngoscopes that use digital and/or fibreoptic technology have been designed to improve visibility when airway difficulty is predicted or encountered. Among these devices, a rigid videolaryngoscope (VLS) uses a blade to retract the soft tissues and transmits a lighted video image to a screen.

OBJECTIVES

Our primary objective was to assess whether use of videolaryngoscopy for tracheal intubation in adults requiring general anaesthesia reduces risks of complications and failure compared with direct laryngoscopy. Our secondary aim was to assess the benefits and risks of these devices in selected population groups, such as adults with obesity and those with a known or predicted difficult airway.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE and Embase on 10 February 2015. Our search terms were relevant to the review question and were not limited by outcomes. We carried out clinical trials register searches and forward and backward citation tracking. We reran the search on 12 January 2016; we added potential new studies of interest from the 2016 search to a list of 'Studies awaiting classification', and we will incorporate these studies into the formal review during the review update.

SELECTION CRITERIA

We considered all randomized controlled trials and quasi-randomized studies with adult patients undergoing laryngoscopy performed with a VLS or a Macintosh laryngoscope in a clinical, emergency or out-of-hospital setting. We included parallel and cross-over study designs.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trial quality and extracted data, consulting a third review author to resolve disagreements. We used standard Cochrane methodological procedures, including assessment of risk of bias.

MAIN RESULTS

We included 64 studies identified during the 2015 search that enrolled 7044 adult participants and compared a VLS of one or more designs with a Macintosh laryngoscope. We identified 38 studies awaiting classification and seven ongoing studies. Of the 64 included studies, 61 included elective surgical patients, and three were conducted in an emergency setting. Among 48 studies that included participants without a predicted difficult airway, 15 used techniques to simulate a difficult airway. Seven recruited participants with a known or predicted difficult airway, and the remaining studies did not specify or included both predicted and not predicted difficult airways. Only two studies specifically recruited obese participants. It was not possible to blind the intubator to the device, and we noted a high level of inevitable heterogeneity, given the large number of studies.Statistically significantly fewer failed intubations were reported when a VLS was used (Mantel-Haenszel (M-H) odds ratio (OR), random-effects 0.35, 95% confidence Interval (CI) 0.19 to 0.65; 38 studies; 4127 participants), and fewer failed intubations occurred when a VLS was used in participants with an anticipated difficult airway (M-H OR, random-effects 0.28, 95% CI 0.15 to 0.55; six studies; 830 participants). We graded the quality of this evidence as moderate on the basis of the GRADE system. Failed intubations were fewer when a VLS was used in participants with a simulated difficult airway (M-H OR, random-effects 0.18, 95% CI 0.04 to 0.77; nine studies; 810 participants), but groups with no predicted difficult airway provided no significant results (M-H OR, random-effects 0.61, 95% CI 0.22 to 1.67; 19 studies; 1743 participants).Eight studies reported on hypoxia, and only three of these described any events; results showed no differences between devices for this outcome (M-H OR, random-effects 0.39, 95% CI 0.10 to 1.44; 1319 participants). Similarly, few studies reported on mortality, noting no differences between devices (M-H OR, fixed-effect 1.09, 95% CI 0.65 to 1.82; two studies; 663 participants), and only one study reporting on the occurrence of respiratory complications (78 participants); we graded these three outcomes as very low quality owing to lack of data. We found no statistically significant differences between devices in the proportion of successful first attempts (M-H OR, random-effects 1.27, 95% CI 0.77 to 2.09; 36 studies; 4731 participants) nor in those needing more than one attempt. We graded the quality of this evidence as moderate. Studies reported no statistically significant differences in the incidence of sore throat in the postanaesthesia care unit (PACU) (M-H OR, random-effects 1.00 (95% CI 0.73 to 1.38); 10 studies; 1548 participants) nor at 24 hours postoperatively (M-H OR random-effects 0.54, 95% CI 0.27 to 1.07; eight studies; 844 participants); we graded the quality of this evidence as moderate. Data combined to include studies of cross-over design revealed statistically significantly fewer laryngeal or airway traumas (M-H OR, random-effects 0.68, 95% CI 0.48 to 0.96; 29 studies; 3110 participants) and fewer incidences of postoperative hoarseness (M-H OR, fixed-effect 0.57, 95% CI 0.36 to 0.88; six studies; 527 participants) when a VLS was used. A greater number of laryngoscopies performed with a VLS achieved a view of most of the glottis (M-H OR, random-effects 6.77, 95% CI 4.17 to 10.98; 22 studies; 2240 participants), fewer laryngoscopies performed with a VLS achieved no view of the glottis (M-H OR, random-effects 0.18, 95% CI 0.13 to 0.27; 22 studies; 2240 participants) and the VLS was easier to use (M-H OR, random-effects 7.13, 95% CI 3.12 to 16.31; seven studies; 568 participants).Although a large number of studies reported time required for tracheal intubation (55 studies; 6249 participants), we did not present an effects estimate for this outcome owing to the extremely high level of statistical heterogeneity (I2 = 96%).

AUTHORS' CONCLUSIONS

Videolaryngoscopes may reduce the number of failed intubations, particularly among patients presenting with a difficult airway. They improve the glottic view and may reduce laryngeal/airway trauma. Currently, no evidence indicates that use of a VLS reduces the number of intubation attempts or the incidence of hypoxia or respiratory complications, and no evidence indicates that use of a VLS affects time required for intubation.