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ORIGINAL ARTICLE
Year : 2018  |  Volume : 11  |  Issue : 4  |  Page : 302-306  

Comparison of different sizes Airtraq™ optical laryngoscope in pediatric patients: A prospective, observational study


Department of Anesthesiology, Seth GS Medical College and KEM Hospital, Mumbai, Maharashtra, India

Date of Web Publication2-Aug-2018

Correspondence Address:
Ketan Sakharam Kulkarni
Near Janata High-School, Mahadeonagar, Islampur, Sangli - 415 409, Maharashtra
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/MJDRDYPU.MJDRDYPU_163_17

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  Abstract 


Background: We aimed at comparing the performance of the three different sizes of AirtraqTM, when performing tracheal intubation in paediatric patients requiring general anaesthesia with endotracheal intubation. Methods: After obtaining informed count from parents, 30 infant, 30 children and 30 adolescent patients underwent tracheal intubation in K.E.M. hospital using AirtraqTM laryngoscope. All patients were intubated by an anaesthetist having at least 5 years of experience in anaesthesia. Results: The Small Airtraq performed best, with less time taken for intubation, no failed intubations, grater percentage of glottic opening score and visual analogue score for ease of use. Optimization manoeuvres were required for intubations in all the patients in infant group; with 5 failed intubations indicating intubation using infant Airtraq was more challenging. Conclusions: Proficiency in using Airtraq in adults may not always translate to successful intubations in infants. Learning curve of an airway gadget is witnessed in its different sized version.

Keywords: Airtraq™ laryngoscope, different sizes of Airtraq, equipment, pediatric patients, tracheal intubation


How to cite this article:
Kulkarni KS, Dave NM, Karnik PP, Garasia MB. Comparison of different sizes Airtraq™ optical laryngoscope in pediatric patients: A prospective, observational study. Med J DY Patil Vidyapeeth 2018;11:302-6

How to cite this URL:
Kulkarni KS, Dave NM, Karnik PP, Garasia MB. Comparison of different sizes Airtraq™ optical laryngoscope in pediatric patients: A prospective, observational study. Med J DY Patil Vidyapeeth [serial online] 2018 [cited 2019 Oct 22];11:302-6. Available from: http://www.mjdrdypv.org/text.asp?2018/11/4/302/238161




  Introduction Top


Conventional direct laryngoscopy requires alignment of all three axes (oral, laryngeal, and tracheal) to obtain a view of the glottic aperture.[1] On the other hand, indirect laryngoscope incorporates optics, and tracheal intubation is performed while looking at an image. Airtraq™ (Fannin [UK] Ltd., Reading, UK) is a disposable, rigid optical indirect laryngoscope. Airtraq™ has been extensively evaluated in adults, but its efficacy in children is still limited in the literature to few randomized controlled trials and case reports where it is shown to improve the ease of intubation [2],[3] and is associated with less movement of the cervical spine.[4],[5] For pediatric patients, Airtraq™ is available in three different sizes: infant (gray color) (endotracheal tube [ETT] size 2.5–3.5 mm ID), pediatric (purple color) (ETT size 4.0–5.5 mm ID), and small (green color) (ETT size 6.0–7.5 mm ID). Pediatric airway is anatomically different from the adult airway and undergoes maturational changes as the child grows. Consequently, ease of intubation using a video-laryngoscope (VL) may vary with the child's age. Hence, we conducted an observational study to determine the performance of three sizes of the Airtraq ® optical VL in Indian pediatric population.


  Materials and Methods Top


This was a prospective observational study. The primary objective was to study the difference in the intubation time and number of attempts required for intubation with the three different sizes of Airtraq. The secondary objective was to study the difference in the visual analog scale (VAS) score, percentage of glottic opening (POGO) score,[6] and optimization manoeuvres. After obtaining Institutional Ethics Committee approval, totally 90 children from day 1 to 12 years of age belonging to the American Society of Anesthesiologists (ASA) Physical Status I–II, undergoing surgery under general anesthesia and requiring endotracheal intubation, were included in this prospective observational study. Written and informed consent was obtained from a parent or a legal guardian. Patients with known congenital heart disease, obvious congenital syndromes, anticipated difficult airway, risk of aspiration, and posted for emergency surgery having ASA physical Status III and above were excluded from the study. All children except infants below 6 months of age were premedicated with injection midazolam 0.05 mg/kg intravenous in the preoperative holding area and wheeled in on a cradle or a trolley to the odds ratio. In the operating room, a standard monitoring including electrocardiogram, noninvasive blood pressure, capnometry, and pulse oximetry was established. Anesthesia was induced with fentanyl 2 μg/kg and propofol 2–3 mg/kg. Injection atracurium 1 mg/kg was used for muscle relaxation. All the patients were given a head neutral position either by placing a head ring or giving a shoulder roll. Patients were intubated with an appropriate size ETT in head neutral position. The tube size selection was done according to age-based formula for children more than 1 year of age, (age in years + 16)/4), and weight-based formula (weight (kg)/10 + 3 mm) for children <1 year of age. The choice of the sized Airtraq VL was in accordance with the manufacturer's recommendations (infant for ETT size 2.5–3.5 mm ID [gray color], pediatric for ETT size 4.0–5.5 mm ID (purple color), and small for ETT size 6.0–7.5 mm ID [green color]). The Airtraq™ was connected to a video monitor. The study included five operators who were qualified anesthesiologists with a minimum experience of 5 years. These operators were skilled at the use of Airtraq VL in adult patients. During intubation with Airtraq™, we recorded the time taken for intubation, number of intubation attempts, POGO score, VAS score, and optimization manoeuvres required. VAS score is the subjective score given by the intubating anesthesiologist with respect to the ease of intubation with 0 being very difficult and 10 being very easy. The POGO score represents POGO seen, defined by the linear span from anterior commissure to the interarytenoid notch. POGO was recorded at the time of successful intubation and not after getting the best laryngeal view. A POGO score of 0 means that even the interarytenoid notch is not seen, while 100% is a full view.

The duration of intubation was defined as time taken from insertion of Airtraq™ to successful intubation confirmed with the appearance of capnogram. Intubation attempt was terminated and labeled as unsuccessful when there was desaturation (SpO2 < 92%), evidence of cardiac instability such as bradycardia or when time taken for intubation exceeded 120 s; whichever occurred earlier. Mask ventilation with 100% oxygen was resumed till oxygen saturation reached 100% before next attempt. For multiple attempts at intubation, intubation time was calculated as the duration of the last attempt. Maximum three attempts were allowed with Airtraq. Intubation was considered a failure after third unsuccessful attempt and patient was intubated with standard Macintosh laryngoscope.

Statistical analysis

Sample size of 90 was estimated by a study using Airtraq™ for intubation in infants and children.[7] A sample size of 30/group in a population of normal distribution was needed to reject the null hypothesis with 90% of power and an alpha error of 0.05. Null hypothesis for our study was that the different sizes of Airtraq would perform equally. Demographic data were analyzed using the Chi-square test. The continuous data were analyzed using the Student's t-test or the Mann–Whitney U-test. P < 0.05 was considered statistically significant.


  Results Top


We studied 41 male and 49 female patients of age between day 2 and 17 years. Their weight ranged between 2.37 and 45 kg (mean weight 16.51 kg) [Table 1]. Demographic characteristics with respect to gender and number of intubations performed by each operator were comparable. The number of intubations performed by each operator in each group is given in [Table 2].
Table 1: Demographic characteristics

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Table 2: The number of intubations performed by each operator in each group

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Average time taken for successful intubation was 38.9, 44.1, 32.63 s in infant, pediatric, and small Airtraq group, respectively. Statistical analysis revealed no significant difference between time to intubate for Airtraq among 3 different sizes (P = 0.2115), [Table 3]. Intergroup analysis also did not show significant difference in time to intubation between any two individual groups. Out of ninety patients, intubation failed in seven patients (5 in infant and 2 in pediatric) and Macintosh laryngoscope was used for securing ETT. Insertion was successful in first attempt in 84.33% (70 out of 83) patients, second attempt in 12.04% (10 out of 83) patients, and third attempt in 3.61% (3 out of 83) patients overall. Third attempt was not required in the small Airtraq group [Table 4].
Table 3: Duration of intubation, percentage of glottic opening score and visual analogue score

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Table 4: Number of intubation attempts

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Average VAS was 7.33, 8.07, and 9.37 in infant, pediatric, and small Airtraq group, respectively. Statistical analysis revealed significant difference between VAS for ease of use of Airtraq among 3 different sizes (P = 0.00824) [Table 3]. In addition, with intergroup analysis, the ease of intubation was more with small Airtraq when compared with the pediatric (P = 0.006594) and infant (P = 0.001486) Airtraq separately. The difference of VAS score between infant and the pediatric group was not statistically significant (P = 0.217103). Average POGO score was 65.67, 85.5, and 92.67 in infant, pediatric, and small Airtraq group, respectively. Statistical analysis revealed a significant difference between POGO for a view of glottis among 3 different sizes (P < 0.0001) [Table 3]. Furthermore, on intergroup analysis, i.e. comparing infant with pediatric, infant with small and pediatric with small the P values were statistically significant (P ≤ 0.00001, <0.00001, 0.002419, respectively). All the intubations in infant group, 25 patients in pediatric group and twenty patients in small Airtraq required optimization maneuvers. Tube rotation was needed in 67, withdrawal of Airtraq in 47, and smaller tube in 4 intubations. External laryngeal manoeuvre was ineffective and did not aid in intubation.


  Discussion Top


Airtraq is an optical laryngoscope which comprises of two side-by-side channels. One channel acts as a conduit through which the tracheal tube is passed while the other contains a special arrangement of optics. Previous studies of Airtraq comparing it with Macintosh have shown favorable results for Airtraq resulting in better view, stable hemodynamics, and lesser manipulations of cervical spine.[2],[3],[4],[5],[6] Airtraq, when compared with C-Mac, showed results favoring Airtraq; with better POGO score, less intubation time, and lesser optimization maneuvers for intubation.[5] However, these studies are mostly in adults. Whether this holds true for Airtraq even in neonates and infants has not been conclusively established.

In our study, even though time to intubate was more in pediatric age group and projects an impression that intubation was difficult in patients where ETT of size 4–5.5 mm ID was used, other parameters such VAS for the ease of use and number of failed intubations suggests that intubation using Airtraq was more challenging in patients taking <3.5 mm ID ETT, i.e. using infant Airtraq. Similarly, in a study by White et al., mean intubation time was less in infant (43 s) than in pediatric (49.2 s) group and infant Airtraq was difficult to use when compared to pediatric Airtraq. This study group did not mention about number of intubation attempts or failed intubations.

In our study, the probable reason for the lower VAS and a higher number of failed intubations in the infant Airtraq could be the inherent anatomy of the larynx in neonates and infants. Neonates and infants have a more anteriorly placed cephalad larynx and an overhanging epiglottis when compared with older children. However, the trajectory at which the tube exits the channel in Airtraq remains fairly constant with all the three sizes, i.e., approximately 18 degrees [Figure 1]. This makes it more likely for the ETT to impinge on the posterior commissure in these age groups. Similar findings regarding superior field of view and difficulty in intubation were seen in a study by White et al.[7] We observed in our study that for successful intubation, the infant Airtraq had to be placed more proximal to the epiglottis which resulted in a lower POGO score in that group.
Figure 1: Tube trajectory while exiting through the channel in Airtraq with all the three sizes

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In initial cases of infant and pediatric Airtraq intubations were tried after getting the highest possible POGO score, which resulted in failure of intubations and higher intubation attempt. The ETT used to slide posteriorly, and even the external manipulation of larynx did not align the tube with the glottic opening leading to unsuccessful intubation. As the operators got acquainted with the device in pediatric population, they could perform successful intubation without any manoeuvres (even without withdrawal of Airtraq). The POGO score recorded was less as compared to the initial intubations. The average POGO score is less as the successful intubations happened in the study later on covered up the initial higher POGO scores.

Rotating the tube within the channel produces a torque and direction of ETT tip can be adjusted. In our study, only 13 patients out of 83 did not require any manoeuvre for tube placement. Tube rotation was the most commonly used manoeuvre, used either alone or in combination with other manoeuvres. Other optimization manoeuvres used were slight withdrawal of Airtraq, external laryngeal manipulation (ELM), using smaller size ETT, and device (Airtraq) rotation. This suggests that even though the laryngeal inlet is clearly seen with Airtraq, additional manoeuvres and hand-eye coordination is equally important. The ELM did help us in improving the glottic view. However, because of the fixed curvature of the VL and fixed the axis of tube progression, we found that the ETT was slipping off posteriorly even when the glottic view was improved with ELM. ELM was used in the initial cases of the study when the incidence of the tube slipping posteriorly was higher. External manipulation as a technique is better performed in VL as both the operator and the assistant can visualize the glottis, and it definitely helped in improving in visualization of glottis. In our study, we recorded the POGO score which resulted in successful intubation and not the POGO score of best laryngeal view. However, the inherent structure of Airtraq made the ELM redundant as it did not lead to successful intubations even if it improved the laryngeal view.

There are some limitations of our study. Five operators who were adept at using VL in adult patients were part of the study. Neither the patients nor the operators were randomized by any method. The number of intubations and age group of the patients in which they were performed were not equal among the operators. Because of high case volume and time pressure at our institute, we were not able to randomize the operators. While the study focused on the comparison of various sizes of Airtraq VL for ease and time taken for intubation and the effectiveness of various manoeuvres, the effect of the learning curve of the operators was not part of this study. We did not study the improvement in the skill of the operators over the course of the study either with regards to VL use in pediatric patients as a whole or with individual sizes of Airtraq VL.

Learning curve of Airtraq is one major drawback similar to any VL. Intubations were performed by anesthesiologists with 5 years of experience in anesthesia, and all of them had used adult Airtraq previously. Further studies may be required to compare all the above parameters when novice anesthesiologists for pediatric airway gadgets performs intubations. The higher incidence of failed intubation, greater number of attempts and prolonged intubation time required in infant and pediatric Airtraq as compared to small Airtraq group also implies that learning curve is not only with a new airway gadget but also with its different-sized versions.


  Conclusion Top


We conclude that proficiency in using Airtraq in adults and older children may not always translate to successful intubations in infants. Slight modification in technique such as the proximal placement of Airtraq, accepting lower POGO scores, and additional manoeuvres may be required.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
Henderson J. Airway management in the adult. In: Miller RD, Eriksson LI, Fleisher LA, Wiener-Kronish JP, Young WL, editors. Millers Anesthesia. 7th ed. New York: Churchill Livingstone Inc.; 2010.  Back to cited text no. 1
    
2.
Maharaj CH, O'Croinin D, Curley G, Harte BH, Laffey JG. A comparison of tracheal intubation using the Airtraq or the Macintosh laryngoscope in routine airway management: A randomised, controlled clinical trial. Anaesthesia 2006;61:1093-9.  Back to cited text no. 2
    
3.
Maharaj CH, Costello JF, Harte BH, Laffey JG. Evaluation of the Airtraq and Macintosh laryngoscopes in patients at increased risk for difficult tracheal intubation. Anaesthesia 2008;63:182-8.  Back to cited text no. 3
    
4.
Hirabayashi Y, Fujita A, Seo N, Sugimoto H. A comparison of cervical spine movement during laryngoscopy using the Airtraq or Macintosh laryngoscopes. Anaesthesia 2008;63:635-40.  Back to cited text no. 4
    
5.
McElwain J, Laffey JG. Comparison of the C-MAC®, Airtraq®, and Macintosh laryngoscopes in patients undergoing tracheal intubation with cervical spine immobilization. Br J Anaesth 2011;107:258-64.  Back to cited text no. 5
    
6.
Ochroch EA, Hollander JE, Kush S, Shofer FS, Levitan RM. Assessment of laryngeal view: Percentage of glottic opening score vs. Cormack and Lehane grading. Can J Anaesth 1999;46:987-90.  Back to cited text no. 6
    
7.
White MC, Marsh CJ, Beringer RM, Nolan JA, Choi AY, Medlock KE, et al. A randomised, controlled trial comparing the Airtraq™ optical laryngoscope with conventional laryngoscopy in infants and children. Anaesthesia 2012;67:226-31.  Back to cited text no. 7
    


    Figures

  [Figure 1]
 
 
    Tables

  [Table 1], [Table 2], [Table 3], [Table 4]



 

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