Comparison of Airtraq™, McCoy™ and Macintosh laryngoscopes for endotracheal intubation in patients with cervical spine immobilisation: A randomised clinical trial

Development of an Artificial Intelligence-Based Image Recognition System for Time-Sequence Analysis of Tracheal Intubation

BACKGROUND

Total intubation time (TIT) is an objective indicator of tracheal intubation (TI) difficulties. However, large variations in TIT because of diverse initial and end targets make it difficult to compare studies. A video laryngoscope (VLS) can capture images during the TI process. By using artificial intelligence (AI) to detect airway structures, the start and end points can be freely selected, thus eliminating the inconsistencies. Further deconstructing the process and establishing time-sequence analysis may aid in gaining further understanding of the TI process.

METHODS

We developed a time-sequencing system for analyzing TI performed using a #3 Macintosh VLS. This system was established and validated on 30 easy TIs performed by specialists and validated using TI videos performed by a postgraduate-year (PGY) physician. Thirty easy intubation videos were selected from a cohort approved by our institutional review board (B-ER-107-088), and 6 targets were labeled: the lip, epiglottis, laryngopharynx, glottic opening, tube tip, and a black line on the endotracheal tube. We used 887 captured images to develop an AI model trained using You Only Look Once, Version 3 (YOLOv3). Seven cut points were selected for phase division. Seven experts selected the cut points. The expert cut points were used to validate the AI-identified cut points and time-sequence data. After the removal of the tube tip and laryngopharynx images, the durations between 5 identical cut points and sequentially identified the durations of 4 intubation phases, as well as TIT.

RESULTS

The average and total losses approached 0 within 150 cycles of model training for target identification. The identification rate for all cut points was 92.4% (194 of 210), which increased to 99.4% (179 of 180) after the removal of the tube tip target. The 4 phase durations and TIT calculated by the AI model and those from the expert exhibited strong Pearson correlation (phase I, r = 0.914; phase II, r = 0.868; phase III, r = 0.964; and phase IV, r = 0.949; TIT, r = 0.99; all P < .001). Similar findings were obtained for the PGY's observations (r > 0.95; P < .01).

CONCLUSIONS

YOLOv3 is a powerful tool for analyzing images recorded by VLS. By using AI to detect the airway structures, the start and end points can be freely selected, resolving the heterogeneity resulting from the inconsistencies in the TIT cut points across studies. Time-sequence analysis involving the deconstruction of VLS-recorded TI images into several phases should be conducted in further TI research.

A comparative study of the C-MAC D-blade videolaryngoscope and McCoy laryngoscope for oro-tracheal intubation with manual in-line stabilization of neck in patients undergoing cervical spine surgery

Background and Aims

Airway management in cervical spine injury patients requires manual in-line stabilization (MILS) of the neck to avoid exacerbation of cord injury, which impedes visualization of glottis during laryngoscopy. Specially designed blades such as McCoy and C-MAC D-blades can improve laryngoscopic view in such patients. This study was performed to compare the efficacy of C-MAC D-blades and the McCoy laryngoscope for oro-tracheal intubation using MILS in patients undergoing cervical spine surgery.

Material and Methods

This randomized, prospective study was performed in 60 adult patients of American Society of Anesthesiologists grade I-III, either sex, 18 to 60 years of age undergoing elective cervical spine surgery. Patients were randomly categorized into two groups, group D and group M. Intubation was performed using a C-MAC D-blade videolaryngoscope in group D and a McCoy laryngoscope in group M using MILS. The intubation difficulty scale (IDS) score, laryngoscopy and intubation times, percentage of glottic opening (POGO) score, Cormack Lehane (CL) grading with and without external laryngeal pressure (ELP), need for bougie or change of blade or operator, and change in hemodynamics following intubation were recorded.

Results

Group D showed lower mean IDS scores than group M (P value < 0.0001). There were statistically significant differences found in duration of laryngoscopy (group D < group M), CL grading without ELP (group D: CL-1,2a >CL-2b, 3; group M: CL-1,2a group M), need for ELP and lifting force (group D < group M), and hemodynamic responses after intubation (group D < group M).

Conclusion

A C-MAC D-blade videolaryngoscope provides better and rapid visualization of glottis with less intubation difficulties than a McCoy laryngoscope during intubation using MILS in patients with cervical spine injury.

Comparison Between McCoy Laryngoscope and C-MAC Video Laryngoscope in Anticipated Difficult Airway: A Prospective Randomised Study

Objective: Prolonged laryngoscopy and failure to intubate are associated with increased morbidity and mortality. Need to improve glottic visualisation and ease of intubation has led to the introduction of various types of laryngoscopes. This study compares the effectiveness of C-MAC video laryngoscope (VL) with McCoy laryngoscope in patients with an anticipated difficult airway.

Methods: This prospective randomised single-blinded single-centre study included patients with modified Mallampati grades 3 and 4, divided into two groups I and II of 65 patients each. Group I was intubated using C-MAC and group II with McCoy Laryngoscope. Modified Cormack Lehane grade of visualisation, time to intubate, intubation difficulty scale score and complications were recorded.

Results: C-MAC VL provides a higher proportion of modified Cormack Lehane grade I visualisation (63% vs 35.3, p=0.0017), the lesser median time of intubation in seconds (15 vs 18, p=0.0007) and significantly lesser median intubation difficulty score (0 vs 3) when compared to McCoy.

Conclusions: C-MAC VL provided better visualisation of glottis and easier tracheal intubation that too in a significantly lesser time. We conclude and recommend the use of C-MAC VL over McCoy for endotracheal intubation in patients with predicted difficult airways, especially in modified Mallampati grades 3 and 4.

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.

Comparisons of Videolaryngoscopes for Intubation Undergoing General Anesthesia: Systematic Review and Network Meta-Analysis of Randomized Controlled Trials

BACKGROUND

The efficacy and safety of videolaryngoscopes (VLs) for tracheal intubation is still conflicting and changeable according to airway circumstances. This study aimed to compare the efficacy and safety of several VLs in patients undergoing general anesthesia.

METHODS

Medline, EMBASE, and the Cochrane Library were searched until 13 January 2020. The following VLs were evaluated compared to the Macintosh laryngoscope (MCL) by network meta-analysis for randomized controlled trials (RCTs): Airtraq, Airwayscope, C-MAC, C-MAC D-blade (CMD), GlideScope, King Vision, and McGrath. Outcome measures were the success and time (speed) of intubation, glottic view, and sore throat (safety).

RESULTS

A total of 9315 patients in 96 RCTs were included. The highest-ranked VLs for first-pass intubation success were CMD (90.6 % in all airway; 92.7% in difficult airway) and King Vision (92% in normal airway). In the rank analysis for secondary outcomes, the following VLs showed the highest efficacy or safety: Airtraq (safety), Airwayscope (speed and view), C-MAC (speed), CMD (safety), and McGrath (view). These VLs, except McGrath, were more effective or safer than MCL in moderate evidence level, whereas there was low certainty of evidence in the intercomparisons of VLs.

CONCLUSIONS

CMD and King Vision could be relatively successful than MCL and other VLs for tracheal intubation under general anesthesia. The comparisons of intubation success between VLs and MCL showed moderate certainty of evidence level, whereas the intercomparisons of VLs showed low certainty evidence.

Tracheal intubation with King Vision video laryngoscope in patients with cervical spine instability-Comparison of straight versus curved reinforced endotracheal tubes

Background and Aims:

King Vision video laryngoscope is commonly used to facilitate intubation in corrective surgery for cervical spine instability patients due to less manipulation. Curved and straight reinforced tracheal tubes are regularly used in this surgery as neck of the patient is likely to be flexed. We aimed to compare intubation characteristics between the curved and straight reinforced tubes through King Vision video laryngoscope in patients to be operated for cervical spine instability with the primary objective being intubation time.

Methods:

Sixty patients undergoing cervical spine surgery were enroled in this prospective randomised comparative clinical study. All were intubated after applying manual in-line stabilisation of the neck, using either curved (group C) or straight (group S) reinforced endotracheal tubes through King Vision video laryngoscope. The intubation time, number of attempts, incidence of tube impingement with arytenoids/aryepiglottic folds, optimisation manoeuvres required and complications were observed. Unpaired ‘t’ test and Chi-square test were used to analyse the data using MedCalc software, version 12.5.

Results:

Time taken for intubation was shorter with curved compared to straight reinforced tube (16.24 ± 3.09 vs. 29.08 ± 5.48 seconds, P < 0.0001) The first attempt success rate was higher using curved than straight reinforced tube (93.3% vs. 70%, P = 0.02). Incidences of impingement with arytenoids/ aryepiglottic folds and optimisation manoeuvres required more with the straight reinforced tube.

Conclusion:

The intubation was fast and with higher first attempt success rate with curved than with straight reinforced tube through King Vision videolaryngoscope when used in patients with cervical spine instability.

A comparative evaluation of Airtraq and Hansraj Video laryngoscopes in patients undergoing tracheal intubation with cervical spine immobilization - A randomized prospective study

Background and Aims:

Airway management is a key concern in trauma patients with cervical spine fracture. Application of manual inline axial stabilization (MIAS) has become the standard of care in these patients. Indirect laryngoscopy only requires alignment of the pharyngeal and laryngeal axis. Hence the primary objective of the study was to compare two indirect laryngoscopes, Airtraq (with adaptor) and Hansraj Video laryngoscopes based on its Intubation Difficulty Score.

Material and Methods:

Sixty anesthetized patients were divided into two groups using computer-based randomization, and tracheal intubation was performed using either Airtraq or Hansraj Videolaryngoscope with cervical spine immobilization.

Results:

Both Airtraq and Hansraj groups were comparable in terms of percentage of glottic opening (POGO) scoring (92 ± 9.88% vs. 89.3 ± 10.4%.) and duration of intubation attempt (14.9 ± 4.36 sec vs. 16.97 ± 3.64 sec). Intubation difficulty scale (IDS) score was significantly shorter with Airtraq (1 ± 0.58 vs. 1.8 ± 0.805; P < 0.0001). The mean duration of time taken for laryngoscopy in Airtraq (12.9 ± 2.07 s vs. 19.06 ± 3.83 s; P < 0.0001)) was significantly shorter and also the duration of time taken to secure airway in Airtraq VL was significantly shorter (29.47 ± 4.75 s vs. 36.03 ± 5.80 sec; P < 0.0001). The heart rate and MABP changes were modest in both groups, but was significantly more in Hansraj VL as compared to Airtraq VL, post-intubation.

Conclusion:

Both Airtraq and Hansraj videolaryngoscope can be used as first-hand device in the scenario of cervical spine stabilization. Airtraq videolaryngoscope is better than Hansraj videolaryngoscope due to shorter IDS and lessor hemodynamic changes.

Effectiveness of intubation devices in patients with cervical spine immobilisation: a systematic review and network meta-analysis

BACKGROUND

Cervical spine immobilisation increases the difficulty of tracheal intubation. Many intubation devices have been evaluated in this setting, but their relative performance remains uncertain.

METHODS

MEDLINE, EMBASE, and the Cochrane Library were searched to identify randomised trials comparing two or more intubation devices in adults with cervical spine immobilisation. After critical appraisal, a random-effects network meta-analysis was used to pool and compare device performance. The primary outcome was the probability of first-attempt intubation success (first-pass success). For relative performance, the Macintosh direct laryngoscopy blade was chosen as the reference device.

RESULTS

We included 80 trials (8039 subjects) comparing 26 devices. Compared with the Macintosh, McGrath™ (odds ratio [OR]=11.5; 95% credible interval [CrI] 3.19-46.20), C-MAC D Blade™ (OR=7.44; 95% CrI, 1.06-52.50), Airtraq™ (OR=5.43; 95% CrI, 2.15-14.2), King Vision™ (OR=4.54; 95% CrI, 1.28-16.30), and C-MAC™ (OR=4.20; 95% CrI=1.28-15.10) had a greater probability of first-pass success. This was also true for the GlideScope™ when a tube guide was used (OR=3.54; 95% CrI, 1.05-12.50). Only the Airway Scope™ had a better probability of first-pass success compared with the Macintosh when manual-in-line stabilisation (MILS) was used as the immobilisation technique (OR=7.98; 95% CrI, 1.06-73.00).

CONCLUSIONS

For intubation performed with cervical immobilisation, seven devices had a better probability of first-pass success compared with the Macintosh. However, more studies using MILS (rather than a cervical collar or other alternative) are needed, which more accurately represent clinical practice.

CLINICAL TRIAL REGISTRATION

PROSPERO 2019 CRD42019158067 (https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=158067).

Comparison of performance characteristics of C-MAC video, McCoy, and Macintosh laryngoscopes in elective cervical spine surgery

Background and Aims:

To compare the performance characteristics of C-MAC video, McCoy, and Macintosh laryngoscopes in elective cervical spine surgery. The primary objective was to assess the ease of intubation with the three study devices. The secondary objectives were the time to intubation and hemodynamic responses during intubation.

Material and Methods :

The prospective observational comparative study was conducted in a tertiary care hospital. Adult ASA 1 and 11 patients who underwent elective cervical spine surgery were included in the study. Patients with unstable spine and trauma were excluded. The analysis of variance, Bonferroni test, Chi square test and multiple comparison tests were used to compare the performance characteristics of laryngoscopes.

Results:

The C-MAC video laryngoscope improved glottis view by improving the modified Cormack–Lehane (CL) score and the percentage of glottis opening (POGO) score compared to McCoy and Macintosh laryngoscopes. The ease of intubation was better with the C-MAC video laryngoscope compared to the McCoy and Macintosh laryngoscopes. The time to intubation was comparable between the three laryngoscopes. The C-MAC video and McCoy laryngoscopes had 100% successful first attempt intubations while it was 90% for the Macintosh laryngoscope. Hemodynamic variables observed during intubation were comparable between the three groups.

Conclusion:

The use of C-MAC video laryngoscope resulted in better visualization of the glottis and easier tracheal intubation as compared to the Macintosh and McCoy laryngoscopes in cervical spine surgery. Both C-MAC video and McCoy laryngoscopes had 100% successful first attempt intubation.

Comparative evaluation of hemodynamic responses and ease of intubation with airtraq video laryngoscope versus macintosh laryngoscope in patients with ischemic heart disease

Introduction:

Hemodynamic responses during laryngoscopy can potentially precipitate ischemia in patients with coronary artery disease. There are conflicting reports regarding the hemodynamic stress responses between the conventional Macintosh and video laryngoscopes. There is a paucity of studies regarding the same in cardiac surgical patients.

Materials and Methods:

A prospective, randomized control study to compare the hemodynamic responses and ease of intubation using Airtraq video laryngoscope and Macintosh laryngoscope in patients with ischemic heart disease.

Results:

Seventy patients were randomized into two groups. Baseline variables including age, weight, Mallampati score, and comorbidities were comparable between the two groups. There was statistically significant elevation in mean heart rate in the Macintosh group at 2^nd-min (P = 0.02) and 3^rd-min (P = 0.05) postintubation. Similarly, there was a significant increase in mean arterial pressure at 2^nd (P = 0.06), 3^rd (P = 0.03), and 4^th (P = 0.03) in the Macintosh group. The time for laryngoscopy and Intubation Difficulty Scale was significantly better in the Airtraq group (P = 0.001 and 0.001). However, the median time to intubation was longer in the Airtraq group (13 s vs. 11 s, P = 0.05). Laryngoscopy view was better with Airtraq even in patients with Mallampati score 3 (ten patients). The incidence of trauma was same in both the groups.

Conclusion:

Airtraq provides the better hemodynamic stability and ease of intubation and may be considered superior to conventional Macintosh laryngoscope for intubation in patients with ischemic heart disease.

A Comparative Evaluation of Hemodynamic Response and Ease of Intubation using Airtraq and McCoy Laryngoscope

Background:

Various airway gadgets have been devised to overcome difficult airway scenario in anesthesia practice. It includes simple rigid laryngoscope to complex fiber-optic intubating devices; however, there is weak evidence to support the superiority of one device over the other.

Aims and Objective:

The ease of intubation, time and the hemodynamic variability between two groups during intubation are considered as the primary outcome measures.

Materials and Methods:

In this prospective study, 60 patients of either sex undergoing elective surgery who required tracheal intubation were included. All the patients of age between 20 and 50 years with the American Society of Anesthesiologists Classes I and II were divided into the following two groups: Group AT (n = 30): the intubation was performed using AT laryngoscope and Group-MC (n = 30); the intubation was performed using MC laryngoscope. The following intubating parameters were recorded: ease of intubation (Grade-I–IV), mean time of laryngoscopy and intubation, Cormack–Lehane grade, and the percentage of glottis opening (POGO) score. The vital parameters such as heart rate (HR) and mean arterial blood pressure (MABP) were recorded only after premedication, and it was taken as the baseline value. These parameters were again recorded at 1 min, 3 min, 5 min, and 10 min after laryngoscopy and intubation. The incidences of sore throat were recorded just before discharge from the recovery room till 24 h of surgery. All these parameters were compared between these two groups using the Student's t-test and Chi-square test.

Results:

There was no significant difference in age, sex, weight, and Mallampati grading between the two groups. More than 30% of patients in Group AT were intubated without an external aid than the Group MC (P < 0.05). In Group AT, the mean time of intubation was 13.5 ± 5.72 s when compared to 15.63 ± 7.28 s in Group MC (P > 0.05). The Cormack–Lehane grade and POGO score were better in the AT group than that of the MC group. The HR at 1 min in Group AT was 101.83 ± 14.50 and in Group MC, it was 108.93 ± 12.86 (P < 0.05) and after 3 min, it was 98.66 ± 12.60 and 111.53 ± 11.67 (P < 0.05), respectively. The MABP was 107.17 ± 9.03 in Group AT compared to 116 ± 10.12 in Group MC (P < 0.05) at 1 min postintubation. The incidences of sore throat were similar in both the groups.

Conclusion:

The AT laryngoscope is better than MC in terms of the ease of intubation, better glottis view, and hemodynamic stability. However, the incidences of sore throat in both groups were comparable.