Journal of Clinical Anesthesia (2014) xx, xxx–xxx

Original Contribution

Comparison of the Airtraq and McCoy laryngoscopes using arigid neck collar in patients with simulateddifficult laryngoscopyQazi Ehsan Ali MD (Professor)a,⁎, Bikramjit Das MD (Senior Resident)a,Syed Hussain Amir MD (Assistant Professor)a,Obaid Ahmed Siddiqui MD (Assistant Professor)a, Shaista Jamil MBBS (Resident)a

aDepartment of Anesthesiology, Jawaharlal Nehru Medical College, A.M.U., Aligarh.,U.P., India

Received 24 September 2012; revised 21 October 2013; accepted 27 October 2013

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Keywords:Airtraq laryngoscope;Difficult airway intubation;Hemodynamic response;Intubation intratracheal:rigid neck stabilization;

McCoy laryngoscope

AbstractStudy Objective: To determine the efficacy of the Airtraq versus the McCoy laryngoscope as intubationdevices with the neck stabilized by a rigid cervical collar.Design: Prospective, randomized, double-blinded study.Setting: Jawaharlal Nehru Medical College.Patients: 60 ASA physical status 1, 2, and 3 patients, aged 18–70 years, scheduled for various surgicalprocedures requiring tracheal intubation for surgical anesthesia.Interventions: Patients were randomly allocated to undergo intubation with the McCoy (n = 30) orAirtraq (n = 30) laryngoscope.Measurements and Main Results: Differences in intubation times between the Airtraq and the McCoylaryngoscope, modified Cormack-Lehane score, percentage of glottic opening (POGO) score, andairway trauma were compared. Overall intubation success rates were 100% with both devices and asimilar number of intubation attempts were required. However, the mean (SD) time required forsuccessful intubation was shorter with the Airtraq (28.73 ± 6.39 sec) than the McCoy laryngoscope(39.11 ± 14.01 sec; P b 0.0001). The frequencies of intubation complications were similar. Esophagealintubation occurred in 4 cases but only with the McCoy laryngoscope.Conclusion: Intubation time was shorter with the Airtraq than the McCoy laryngoscope, even though theoverall success rates between the two devices were similar.© 2014 Elsevier Inc. All rights reserved.

1. Introduction

⁎ Correspondence: Qazi Ehsan Ali, MD, Department of Anesthesiology,N. Medical College, A.M.U., Aligarh., India. Tel.: +91 741 770 1769;x: +91 571 272 0030.E-mail address: qaziehsanali@gmail.com (Q.E. Ali).

ttp://dx.doi.org/10.1016/j.jclinane.2013.10.012952-8180/© 2014 Elsevier Inc. All rights reserved.

The Airtraq (Prodol Meditec S.A., Vizcaya, Spain) is anovel optical laryngoscope which was developed to facilitatetracheal intubation [1]. As a result of the exaggeratedcurvature of the blade and internal arrangement of the opticalcomponents, a view of the glottis is provided withoutalignment of the oral, pharyngeal, or tracheal axes [2]. The

2 Q.E. Ali et al.

Airtraq laryngoscope requires less cervical spine movementthan conventional laryngoscopy with a Macintosh laryngo-scope [3], and it is effective when the neck is stabilized in theneutral position in manikins [4] and in humans [5]. The distalhinged tip of the McCoy laryngoscope (Penlon Ltd.,Abingdon, UK) improves laryngoscopic views when theneck is immobilized by a cervical collar [6]. When the neckwas manually stabilized in the neutral position, laryngo-scopic views were improved in 86% of Cormack-Lehanegrade 3 cases with the Macintosh laryngospope [7].

The Airtraq and McCoy laryngoscopes had yet to becompared in a simulated difficult airway in humans. Wecompared the two devices as aids for tracheal intubation inpatients whose necks were immobilized by rigid cervicalcollars.

2. Materials and methods

With approval of the Hospital Ethics Committee ofJawaharlal Nehru Medical College and written, informedconsent, we enrolled 60 ASA physical status 1, 2, and 3patients, age 18 to 70 years, scheduled for various surgicalprocedures requiring tracheal intubation for surgical anesthesia.Exclusion criteria were increased risk of pulmonary aspiration,cervical spine pathology, or anticipated airway difficulties(Mallampati grade 4 or thyromental distance b 6 cm).

Before induction of anesthesia, each patient’s head waselevated with a pillow. Anesthesia was induced with fentanyl2 μg/kg and propofol 2 mg/kg; after confirmation offacemask ventilation, vecuronium 0.1 mg/kg was given forneuromuscular blockade. Anesthesia was maintained withsevoflurane 2% in oxygen. After full neuromuscularblockade, the pillow was removed and a rigid PhiladelphiaCervical Collar (Tracheostomy Philadelphia Collar; Phila-delphia Cervical Collar Co., Thorofare, NJ, USA) of theappropriate size was positioned around the neck. Patientswere then randomly allocated to tracheal intubation with anAirtraq preloaded with an endotracheal tube (ETT; 7 mminternal diameter [ID] for women and 8 ID mm for men) orMcCoy laryngoscope with a styletted ETT.

Randomization was based on computer-generated codessealed in sequentially numbered opaque envelopes. Forpatients allocated to intubation with the Airtraq, the devicewas inserted into the mouth and positioned with the glottisseen at the center of the eye piece. The ETT was thenadvanced into the trachea and the scope was detached andremoved from the mouth. Finally, the respiratory circuit wasconnected and ventilation confirmed with side streamcapnography. For patients assigned to intubation with theMcCoy laryngoscope, the best possible glottic view wasobtained with a size 3 McCoy laryngoscope withoutactivation of the distal hinged tip (Macintosh configuration).Subsequently, the distal hinged tip was activated by pressingthe lever. In this activated McCoy configuration, the glottic

view was evaluated and intubation was attempted with anETT (7 mm ID for women and 8 ID mm for men) primedwith a stylet. The stylet was then removed from the ETT andthe respiratory circuit was connected to confirm ventilation.With either device, tracheal intubation was deemed a failureif it was not accomplished within three attempts atintubation, and any single forward movement of the Airtraqor any single insertion of the McCoy laryngoscope blade intothe mouth, or any single ETT advancement to attemptintubation, was considered an attempt. The rigid Philadelphiacollar was removed in patients whose tracheas were notintubated within three attempts; the trachea was then intubatedconventionally using a size 3 Macintosh blade. All intubationswere performed by a single anesthesiologist whose previousexperience included more than 100 intubations with eachdevice system.

Morphometric data, Mallampati scores, mouth opening(interincisor distance), thyromental distance, and sterno-mental distance (with head extended in the upright position)were measured by an observer blinded to group assignment.With the patient in the supine position and the cervical collarin place, mouth opening was measured before intubation byan observer blinded to group assignment. The followingoutcomes were recorded by an unblinded observer: overallintubation success rate; number of intubation attempts;intubation time (defined as the time from picking up theAirtraq or McCoy laryngoscope until appearance of thecapnograph waveform through the ETT); frequency ofesophageal intubation; mucosal trauma (ie, blood detectedon the devices); lip or dental injury; and hypoxia (oxygensaturation b 95%). Reasons for failed attempts when multipleattempts at intubation were required or overall intubationwas unsuccessful also were recorded. For patients assignedto intubation with the McCoy laryngoscope, the intubatinginvestigator reported the modified Cormack-Lehane laryn-goscopy grade [8] and the percentage of glottic opening(POGO) score [9] with the laryngoscope in the Macintoshconfiguration and the activated McCoy configuration.

The primary outcome measure of the study was thedifference in intubation times between the Airtraq and theMcCoy laryngoscope. In a preliminary study [10], the mean± SD intubation time with the Airtraq and optimal intubationconditions was 12.2 ± 8.5 sec. Assuming that the SD ofintubation times for both the Airtraq and McCoy laryngo-scope in patients with a collar in place was also 9 seconds, wecalculated that 30 patients in each group would provide 90%power to detect a 10-second difference in mean intubationtimes between the groups, with a two-tailed alpha of 0.05.We thus enrolled 60 patients in the study.

Noncontinuous data were compared with Mann–WhitneyU-tests. The frequency of intubation complications and theoverall intubation success rate were tested by the Fisher’sExact or chi-square tests as appropriate. Continuous datawere compared using unpaired t-tests. For patients assignedto the McCoy laryngoscope group, modified Cormack-Lehane scores and POGO scores with the laryngoscope in

Table 2 Intubation attempts with the two devices

Intubation attempts (n) Airtraq (n = 30) McCoy (n = 30)

1 17 162 11 10

3Airtraq vs McCoy with rigid neck collar

the Macintosh configuration and the activated McCoyconfiguration were compared with the Wilcoxon signed-rank test. Statistical analysis was performed using SPSSsoftware (version 17.0; SPSS Inc., Chicago, IL, USA). A P-value b 0.05 was considered significant.

3 2 4

Airtraq optical laryngoscope (Prodol Meditec S.A., Vizcaya, Spain);McCoy laryngoscope(Penlon Ltd., Abingdon, UK).

3. Results

Demographic parameters and airway assessment data ofpatients are shown in Table 1. Overall intubation successrates were 100% for both devices. The number of first,second, and third attempts at intubation were 17, 11, and 2,respectively, for the Airtraq, and 16, 10, and 4 attempts,respectively, for the McCoy laryngoscope (P = 0.76;Table 2). Time to intubation was significantly faster withthe Airtraq (28.73 ± 6.39 sec) than the McCoy laryngoscope(39.11 ± 14.01 sec; P b 0.0001; Table 3).

For patients randomized to the McCoy laryngoscopegroup, the modified Cormack-Lehane scores were worse inthe Macintosh configuration than the activated McCoyconfiguration (P b 0.0001). Glottic structures were notvisible (ie, modified Cormack-Lehane grade 3a or greater) in20 patients with the Macintosh configuration compared withonly 8 patients with the McCoy configuration. The Cormack-Lehane grade 2a view was the best view achieved with theMcCoy configuration. Of the 20 patients with a grade 3aview in the Macintosh configuration, activation of the distalhinged tip (McCoy configuration) improved the view tograde 2b in 6 patients and grade 2a in 5 other patients.However, in 9 patients, the view remained grade 3a. Of 6patients with grade 2b views with the Macintosh configu-ration, the view improved to grade 2a with the McCoyconfiguration in 4 patients, but remained unchanged in twoother patients. No improvement was noted in the 4 patientswith a grade 2a view with the Macintosh configuration whenthe movable tip of the McCoy blade was deployed. The meanPOGO score was also worse in the Macintosh configuration

Table 1 Demographic parameters and airway assessment data

Parameters Airtraq (n=30) McCoy (n=30)

Men:women 18:12 16:14Age (yrs) 35.96 (10.92) 38.76 (9.09)Weight (kg) 65.8 (9.7) 63.7 (9.34)Body mass index (kg/m2) 24.08 (2.41) 23.44 (2.83)ASA physical status (median) 1 1Airway measurementsThyromental distance (cm) 6.8 6.5Inter incisor distance (cm) 4.3 4.5Mallampati grade: 1 / 2 / 3 / 4 22 / 8 / 0 / 0 21 / 9 / 0 / 0

Data are means (SD) or numbers (%).Airtraq optical laryngoscope (Prodol Meditec S.A., Vizcaya, Spain);McCoy laryngoscope (Penlon Ltd., Abingdon, UK).

(43%; SD 2.4) than in the McCoy configuration (69.5%; SD3.6); P b 0.0001.

There were 4 esophageal intubations with the McCoylaryngoscope, but none with the Airtraq (P = 0.034).Mucosal trauma occurred in two patients with the McCoylaryngoscope and three patients with the Airtraq (P N 0.99).Lip injury occurred in two patients with the Airtraq, but nonewith the McCoy laryngoscope (P = 0.22). There were nodental injuries or hypoxia observed in either group (Table 3).

Reasons for failed intubation (at the first or secondattempt) using the McCoy laryngoscope were tactileresistance encountered while advancing the ETT into thetrachea due to limited oropharyngeal space caused by limitedmouth opening (n = 6), suboptimal laryngoscopy becauselimited mouth opening prevented adequate blade insertion(n = 4), and esophageal intubation (n = 4). All esophagealintubations occurred on the first attempt, and were correctedat the second attempt with the McCoy laryngoscope.Intubations with the Airtraq failed because of difficulty inpositioning the blade’s tip posterior to the epiglottis.

4. Discussion

Both the Airtraq and McCoy laryngoscopes offer highsuccess rates when difficult airways are simulated byapplication of a rigid cervical collar. However, intubationwas about 10.38 seconds faster with the Airtraq and was less

Table 3 Comparison of success rate and complications witheach device

Parameters Airtraq(n=30)

McCoy(n=30)

Overall success rate (%) 30 (100) 30 (100)Intubation time (sec) 28.73 (6.39) 39.11 (14.01) ⁎

Lowest SpO2 duringintubation attempts (%) 99.1 98.7

Esophageal intubation 0 4 ⁎

Airway traumamucosa / lip / dental 3 / 2 / 0 2 / 0 / 0

Data are means (SD) or numbers (%).Airtraq optical laryngoscope (Prodol Meditec S.A., Vizcaya, Spain);McCoy laryngoscope (Penlon Ltd., Abingdon, UK).SpO2 = arterial oxygen saturation as measured by pulse oximetry.

⁎ statistically significant difference.

4 Q.E. Ali et al.

likely to result in esophageal intubation than was the McCoylaryngoscope. The Airtraq was successful in all patients,although multiple attempts were required in 43.33% ofpatients. All failed attempts with the Airtraq resulted fromthe tip of the introducer blade advancing into the vallecularather than under the epiglottis. However, this event waseasily corrected by partially withdrawing the device and,with a subsequent scooping movement of the introducerblade, lifting the epiglottis and advancing the ETT into thetrachea. Only a few seconds were required for this maneuver,which helps explain why intubation times with the Airtraqwere faster than with the McCoy laryngoscope.

The tracheas of patients with modified Cormack-Lehanegrade 2a or 2b presumably could have been intubated withthe McCoy blade in the Macintosh configuration. It also maybe argued that activation of the McCoy blade prolonged thetime for intubation and contributed to slower intubationtimes with this device. For the 10 patients with modifiedCormack-Lehane grades 2a or 2b and with the McCoy bladein the Macintosh configuration, the mean intubation timewas 32.13 seconds. Even subtracting the few secondsrequired for McCoy blade activation from the intubationtimes in these patients resulted in longer intubation times inthe entire McCoy group than the Airtraq group.

There were no esophageal intubations noted in the Airtraqpatients. The Airtraq provided a nearly complete laryngealview and allowed the operator to observe advancement of theETT into the trachea from outside the larynx. Thiscontinuous view allowed detection of inaccurate ETTadvancement, which was then corrected before esophagealintubation. In contrast, esophageal intubation occurred in13.33% of McCoy laryngoscope patients. This situation mayhave been been attributed to poor glottic visibility and poormaneuverability of the ETT due to limited oropharyngealspace caused by limited mouth opening.

In spite of the relative bulkiness of the introducer blade, theAirtraq may be used in patients whose mouth opening is assmall as 20 mm [11]. However, all lip injuries with the Airtraqoccurred when the introducer blade was first introduced intothe mouth and were related to the bulkiness of the introducerblade rather than the patients’ limited mouth opening. Incontrast, the McCoy laryngoscope, which is less bulky(especially in blade width), did not cause any lip injury.Mouth opening and neck mobility were both decreased byapplication of a rigid cervical collar. The average 20-mmmouth opening noted in our patients was similar to what wasreported previously with the same rigid cervical collar [12,13].

In the current study, the cervical collar generatedCormack-Lehane grade 3 or 4 views in 66.67% of patientsassigned to the McCoy laryngoscope group (in theMacintosh configuration). This finding was similar to thatwhich was reported with the Philadelphia and other cervicalcollars [13–16], although no modified Cormack-Lehanegrade 3b or 4 views were observed in the current study. TheMcCoy laryngoscope was tested previously in difficultairway scenarios simulated by application of a rigid cervical

collar [6] or manual inline stabilization [7]. With a cervicalcollar in place, the McCoy laryngoscope improved theCormack-Lehane laryngoscopic view by at least one grade in45% of patients [6], which was similar to the 36.67%improvement observed. However, 92% of those patients withgrade 3 or 4 views improved to grade 1 or 2 after activationof the McCoy blade, which was substantially moreimprovement than the 56.67% that was observed. It is likelythat the difference simply reflected the types of collars used,their sizes in relation to the patients, and how they wereapplied. Laurent et al [7] reported that Cormack-Lehanelaryngoscopic views improved at least one grade in 49% ofpatients whose necks were kept in the neutral position withmanual inline stabilization. They also found that 86% ofgrade 3 or 4 views improved to grade 1 or 2 views withactivation of the McCoy blade, which is a greaterimprovement than the 56.67% improvement observed.With proper maneuvers, including fine wrist movementand centralizing the vocal cord in the view finder, theCormack-Lehane score in the Airtraq group was grade 1 andthe glottic view was 100%.

The modified Cormack-Lehane laryngoscopy grade wassupplemented with the POGO score because it is continuousand might provide greater sensitivity for subtle improve-ments in laryngoscopic view resulting from activation of theMcCoy blade. In most of the patients, the modifiedCormack-Lehane grade remained 2b or above even afterMcCoy blade activation. Consequently, POGO scoringproved less useful since it remains at zero at all Cormack-Lehane grades exceeding 2b.

Direct laryngoscopy was not required with the Airtraq.However, a limitation of the Airtraq for routine use is that itis a single-use device and may be costly.

Our study did not include a third study arm comparing theMacintosh laryngoscope (the most commonly used intuba-tion modality) with the other two intubation techniques.Previous studies indicated that application of a cervical collarfrequently produced Cormack-Lehane grade 3 or 4 views[14,15], and that the intubation success rate with a Macintoshlaryngoscope was only about 60% [16]. Laryngoscopicviews provided by the Macintosh blade configuration werereported when the McCoy laryngoscope was used.

5. Conclusion

In conclusion, both the Airtraq and the McCoy laryngo-scopes offer high success rates in simulated difficult airwaywith application of a rigid cervical collar that immobilizesthe cervical spine and limits mandibular mobility. However,the Airtraq was 10.38 seconds faster than the McCoylaryngoscope and less likely to result in esophagealintubation. The Airtraq thus appears preferable to theMcCoy laryngoscope in simulated difficult airway situations,especially in immobilized cervical spine patients.

5Airtraq vs McCoy with rigid neck collar

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