|Ahead of print publication
Comparison of Airtraq™ versus C-MAC® videolaryngoscope for tracheal intubation in children with normal airways
Barkha Agrawal, Nandini Dave, Raylene Dias, Ketan Kulkarni, Harick Shah
Department of Pediatric Anesthesia, Seth GS Medical College and KEM Hospital, Mumbai, Maharashtra, India
|Date of Submission||24-Jul-2020|
|Date of Decision||07-Aug-2020|
|Date of Acceptance||25-Aug-2020|
Dept. of Paediatric Anaesthesia, 3rd Floor, Old Building, Besides Ward 3, KEM Hospital, Parel, Mumbai - 400012, Maharashtra
Source of Support: None, Conflict of Interest: None
Background and Aims: When compared with direct laryngoscopes, videolaryngoscopes can provide a significantly better view of the larynx. There are no studies in children directly comparing Airtraq™ and C-MAC® videolaryngoscopes. We aimed to compare intubating characteristics between these two devices in pediatric patients. The primary outcome measure was the time needed for successful intubation and secondary outcome measures were the number of attempts to intubate, ease of intubation, percentage of glottic opening (POGO) score, optimization maneuvers and complications such as airway trauma and esophageal intubation. Materials and Methods: One hundred and twelve children aged 1–12 years undergoing elective surgery under general anesthesia are quiring tracheal intubation were enrolled. Children were randomized into two groups using computer generated randomization sequence. The t-test was used for analyzing quantitative data, nonparametric data were analyzed using Mann–Whitney test, and categorical data were analyzed using the Chi-square test. Results: Time to tracheal intubation was significantly longer with Airtraq™ (41.0 s) compared to C-MAC® (23.4 s); P < 0.001. The number of attempts at tracheal intubation was more with Airtraq™ (P = 0.008). Seventy-five percent of anesthesiologists found C-MAC® easy to use. POGO score was >90% in both groups without maneuvers. Conclusion: The study found that in pediatric patients with normal airways, time to intubation was faster with C-MAC® as compared to AirtraqTM. C-MAC® also performed better in aspects like the number of attempts and ease of intubation.
Keywords: AirtraqTM, anesthesia, C-MAC®, pediatric, videolaryngoscopy
|How to cite this URL:|
Agrawal B, Dave N, Dias R, Kulkarni K, Shah H. Comparison of Airtraq™ versus C-MAC® videolaryngoscope for tracheal intubation in children with normal airways. Med J DY Patil Vidyapeeth [Epub ahead of print] [cited 2021 Dec 6]. Available from: https://www.mjdrdypv.org/preprintarticle.asp?id=321944
| Introduction|| |
Endotracheal intubation is considered the gold standard for airway management during anesthesia.,, Conventionally, direct laryngoscopy using the Macintosh or Miller laryngoscopes have been used for directly visualizing the structures of the larynx and facilitating tracheal intubation in children. In recent years, video laryngoscopes, based on the principles of indirect laryngoscopy, have been introduced into clinical practice. When compared with direct laryngoscopes, video laryngoscopes can provide a significantly better view of the larynx, which may be useful in situations of difficult tracheal intubation., Although video laryngoscopes provide a good view of the larynx, they may not guarantee easy tracheal intubation and may prolong the time required for successful intubation. As with any new device, there is a learning curve with video laryngoscopes. However, video laryngoscope design is similar to conventional laryngoscopes, thereby helping anesthetists familiar with direct laryngoscopy, to increase their success rate, without the need for any special training. In addition, teaching intubation to novice anesthetists in both adults and pediatrics using video laryngoscopes, is found to be useful because of a shared view for the teacher and the novice anesthetist.,,
The Airtraq™ (ProdolMeditec S. A., Vizcaya, Spain) is a novel single-use video laryngoscope that provides glottic display without any deviation in the normal position of the oral, pharyngeal, or the tracheal axis. The blade of Airtraq™ consists of two side-by-side channels – one acts for placement and insertion of the tracheal tube, while the other channel terminates in a distal lens.
The C-MAC® video laryngoscope (Karl Storz, Tuttlingen, Germany) blade design is similar to the Macintosh, with the additional advantage of a video camera. It provides an 80° field of view, and the image can be captured electronically in video or in still format and displayed on the dedicated monitor. It can be used in a similar way to Macintosh for direct laryngoscopy and also for indirect laryngoscopy when the operator views the larynx on the video screen. Since the C-MAC® incorporates a Macintosh blade, which most anesthesiologists are familiar with, we hypothesized that proficiency might be easier to acquire than with other indirect laryngoscopes.
In normal airway in infants and children, White et al. found that Airtraq™ laryngoscope provides an improved view of the larynx compared with conventional laryngoscopy; however, tracheal intubation takes longer. Similarly, in normal airway in children, Vlatten et al. showed that C-MAC® videolaryngoscope takes a longer period but provides a better view of the larynx compared to direct laryngoscopy. There are no studies in children directly comparing intubation with these two videolaryngoscopes, a channeled versus a nonchanneled one. Hence, we aimed to compare Airtraq™ and C-MAC® videolaryngoscopes for tracheal intubation in pediatric patients.
| Materials and Methods|| |
After approval from the Institutional Ethics Committee (Letter number: EC/OA-72/2017; Approval date: January 18, 2018) and parental consent, 112 children aged 1–12 years, American Society of Anesthesiologists (ASA) Grade 1, 2, undergoing elective surgery under general anesthesia requiring tracheal intubation were recruited in this randomized controlled study. The study was conducted over a period of 1 year. Children with anticipated difficult airways, recent respiratory tract infection, morbid obesity, gastro-esophageal reflux, and increased risk of aspiration were excluded.
Prior to induction of anesthesia, one of the two video laryngoscopes (Airtraq™ or C-MAC®) was chosen randomly, using computer generated randomization sequence (simple random allocation). The random allocation sequence was concealed from the doctors enrolling patients into the study. Children for whom laryngoscopy was performed using Airtraq™ were designated as Airtraq™ group and for whom C-MAC® was used were designated as C-MAC® group.
Anesthetists in our study had a minimum of 3 years of experience in pediatric anesthesia. All anesthetists were experienced in using Airtraq™ videolaryngoscope with at least 20 intubations done in adults. All anesthetists have vast experience in direct laryngoscopy. Since C-MAC® is similar to use to direct laryngoscopy, we assume that they are comfortable in using the C-MAC® device. In addition, we ensured that anesthetists have used C-MAC® at least ten times.
Before the induction of anesthesia, all patients received IV midazolam 0.03 mg/kg as premedication. After preoxygenation, anesthesia was induced with propofol 2–3 mg/kg and fentanyl 2 μg/kg. Following confirmation of adequate mask ventilation, IV atracurium 0.6 mg/kg was administered for muscle relaxation. Two and a half minutes later, laryngoscopy and endotracheal intubation were performed. PaediatricAirtraq™ (purplecolour for size 4.0–5.5 Rusch® endotracheal tube [ETT] andgreen color for size 6.0–7.5 ETT) was used in AirtraqTM group and C-MAC® size 2 Macintosh blade was used in C-MAC® group. Anesthesia was maintained with oxygen, air, and sevoflurane. Monitoring included oxygen saturation, end-tidal CO2, noninvasive blood pressure, and electrocardiogram.
The data collected included time to tracheal intubation, ease of intubation, percentage of glottic opening (POGO) score, and optimization maneuvers needed to facilitate intubation. Time to tracheal intubation was defined as the time elapsed from the insertion of the blade between the dental arches until the ETT was placed through the vocal cords, as confirmed visually by the operator. Correct ETT placement was confirmed by capnography and auscultation. For patients in whom the ETT was not directly visualized passing through the vocal cords, the intubation attempt was not considered complete until evidence for the presence of carbon dioxide in the exhaled breath was obtained.
The primary outcome measure was time needed for successful intubation. Secondary outcome measures were the number of attempts to intubate, ease of intubation, POGO scoring, and complications such as airway trauma and esophageal intubation.
If time to intubate took longer than 60 s or saturation dropped <95%, whichever was earlier, the device would be removed, and the patient ventilated with the face mask. A maximum of two attempts were permitted, after which the anesthesiologist would use a direct laryngoscope. A failed intubation attempt was defined as an attempt, in which the trachea was not intubated, or where the device was abandoned, and another device utilized. The timing was observed by a member of the research team using a stopwatch. Ease of intubation for the operator was self-reported and recorded after intubation using a score of 1–5 (1- very difficult, 2- difficult, 3- neutral, 4- easy, and 5- very easy).
Optimization maneuvers performed to improve the line of sight included optimal external laryngeal manipulation (OELM) and slight movements of the blade once placed into the vallecula to lift the epiglottis. The POGO score was 100% if the entire glottis was visualized from the anterior commissure to the posterior cartilages and 0% if none of the glottic openings was visible,,OELM was applied for the best glottic view if the initial POGO score was 75%. The POGO after the application of the OELM was noted. When the C-MAC® was utilized, additional optimization maneuver used was to shape the ETT into a hockey stick conformation with a stylet.
For each attempt with the C-MAC®, it was used as an indirect laryngoscope with the screen. To use Airtraq™ as video laryngoscope, we utilized the adapter with a phone having the app “Airtraq mobile” [Figure 1]. The universal adapter is designed to be used exclusively in combination with the Airtraq™ for tracheal intubation. The adapter fits most smartphones, providing a real-time image of the glottis.
The POGO score was reported by the anesthesiologist performing the laryngoscopy. While the number of attempts for successful intubation, optimization maneuvers, and complications were noted by a member of the research team not blinded to group allocation.
The sample size was calculated based on the primary efficacy parameter, i.e., mean time to intubation based on a previous study done by McElwain and Laffey Mean intubation time with C-MAC® was 11 s while that with Airtraq™ was 7 s with a standard deviation (SD) of 3 s. A difference of 20 s in the meantime to intubation was determined to be clinically significant. The noninferiority/superiority margin was 5 s. Based on these parameters, the sample size was found to be 112, with 56 patients in each group.
The quantitative data, when normally distributed, were represented as their mean ± SD. Categorical and nominal data were expressed in percentage. The t-test was used for analyzing quantitative data, nonparametric data were analyzed using the Mann–Whitney test and categorical data were analyzed using Chi-square test. The significance threshold of P value was set at <0.050. All analysis was carried out using GraphPadInStat V3.04 software. (GraphPad Software 2365 Northside Dr. Suite 560 San Diego, CA - 92108 USA).
| Results|| |
Out of the total 112 children recruited, all provided complete data and were included in the analysis [Figure 2]. There were no significant differences in patient characteristics between the two groups [Table 1]. All 112 patients were successfully intubated with either C-MAC® orAirtraq™.
The time to tracheal intubation was significantly longer with Airtraq™ (41.0 s) as compared to C-MAC® (23.4 s; P < 0.001) [Table 2].
|Table 2: Intubating characteristics and performance of AirtraqTM and C-MAC® videolaryngoscopes|
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The number of attempts at tracheal intubation was more with Airtraq™. (P = 0.008). 75% of anesthesiologists found C-MAC® easy to use (ease of intubation score 4 and 5; P < 0.001) [Table 2]. With regard to the POGO score, there was no significant difference between the use of C-MAC® and Airtraq™. The POGO score was >90%in both groups without maneuvers.
OELM was required in three patients in Airtraq™ group for inserting the ETT. No maneuvers were required in the C-MAC® group.
There was no incidence of desaturation or complications such as bradycardia, esophageal intubation, trauma in either group.
| Discussion|| |
Difficult and failed intubation is an important cause of anesthetic morbidity and mortality. Laryngeal view at laryngoscopy is a significant factor which determines the difficulty of intubation. To get the best laryngeal view and to perform easy intubation, several indirect laryngoscopes have recently been developed. In this prospective study, we aimed to compare two of these video laryngoscopes: C-MAC® and Airtraq™ in pediatric patients, as there is a paucity of extensive comparative studies using these devices in this age group.
We found that time taken to tracheal intubation was significantly lesser with C-MAC® as compared to Airtraq™. The average duration for tracheal intubation by Airtraq™ was 41s and with C-MAC® it was 23.4s (P < 0.001). A randomized controlled trial (RCT) conducted by Vlatten et al. in 2012 comparing Airtraq™ with Macintosh laryngoscope in children <5 years of age showed similar results. Although the glottic view assessed using POGO score was more superior using Airtraq™ (100%), the time for tracheal intubation was more prolonged compared to the Macintosh laryngoscope (22.5 s vs. 18 s).The authors also reported that compared with adults, the full view of the larynx occupied a much smaller portion of the eyepiece view in the pediatric AirtraqTM which may have increased the time to tracheal intubation. This has been reported by other authors as well. Although the laryngeal view provided with Airtraq™ is good, guiding the pediatric ETT through the vocal cords may not always be straightforward. The separate channel used to guide the ETT in Airtraq™ may have contributed to the prolonged intubation in our patients. Furthermore, the C-MAC® blade is similar to direct Macintosh laryngoscope, which most anesthesiologists are well acquainted with which explains the shorter time taken for intubation using this device.,,
In this study, intubation attempts were significantly more with Airtraq™ as compared to C-MAC® (P = 0.008). The basic difference between direct and indirect laryngoscopy lies in the fact that the glottic view is much better with indirect laryngoscopes as they have a more focused field of vision, but they require good hand-eye coordination. This may make intubation comparatively more difficult with indirect laryngoscopes. We found that C-MAC® video laryngoscope was much easier to use. Although the curvature of Airtraq™ follows a natural anatomical curve which requires minimum positioning, most anesthesiologists found it difficult and rated it very difficult to use (P < 0.001).
The POGO score represents the POGO seen, defined by the linear span from the anterior commissure to the inter-arytenoid notch. We found that in this study, the POGO score visualized was almost the same for C-MAC® and Airtraq™, reaching almost 100% with both instruments. The results are similar to previous studies., However, a study by J. McElwain and Laffey finds that the Airtraq™ group had significantly better POGO scores at laryngoscopy compared with C-MAC®. This could be because this study was conducted when performing tracheal intubation in patients undergoing neck immobilization using manual inline axial cervical spine stabilization.
With Airtraq™ 3 out of 56 patients required OELM for maneuvering the ETT. This is contrary to a previous study in which a greater number of optimization maneuvers were required with C-MAC® compared with Airtraq™ The OELM ultimately increases the total time taken for tracheal intubation.
No failed or second intubation attempt was associated with significant complications. Pulse oximetry (SpO2) did not drop <94% during intubation in either group.
A recent meta-analysis has reviewed 14 RCTs video laryngoscopes with direct laryngoscope pediatric patients. The authors of this meta-analysis demonstrated that although video laryngoscopes improved glottic visualization in pediatric patients, this was at the expense of prolonged time to intubation and increased failures. The meta-analysis stated that further studies are needed to clarify the efficacy and safety of video laryngoscopes in hands of nonexperts and in vulnerable populations like children and in those with airway problems. Although some trials have compared the efficacy between video laryngoscopes and direct laryngoscope in children, most of the trials have been limited to a small sample size; some results were varied or even conflicting.
We conducted a RCT using a large sample size. There are, however, certain limitations of this study. It is impossible to blind the operator to the laryngoscope they are using, so they might be biased while grading ease of intubation. POGO scoring is also subjective in nature. All intubations in this study were done by experienced anesthesiologists, and hence, we were unable to comment on how novices and trainees will behave while using these instruments. This may be a directive for future research. All intubations were done on patients having ASA Grades 1, 2 posted for elective procedures. Further studies are needed to clarify the use of these instruments in difficult airways and in emergency situations.
| Conclusion|| |
The study found that in pediatric patients with normal airways, time to intubation was faster with C-MAC® as compared to Airtraq™. C-MAC® also performed better in aspects like the number of attempts and ease of intubation.
The study was funded by the Department of Paediatric Anaesthesia, GSMC and KEM Hospital, Mumbai. We would like to thank the Dean Dr. Hemant Deshmukh for permitting us to undertake the study.
Financial support and sponsorship
The study was funded by the Department of Paediatric Anaesthesia, GSMC and KEM Hospital, Mumbai.
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2]
[Table 1], [Table 2]