|Year : 2014 | Volume
| Issue : 1 | Page : 169-173
A comparative study on tracheal intubation using Airtraq laryngoscope versus Macintosh laryngoscope in morbidly obese patients
Osama El Sharkawy, Sabry Ibrahim
Department of Anaesthesiology, Faculty of Medicine, El Menofiya University, Menufia, Egypt
|Date of Submission||13-May-2013|
|Date of Acceptance||27-Oct-2013|
|Date of Web Publication||20-May-2014|
Osama El Sharkawy
Resident of Anaesthiology Ahmed Maher Teaching Hospital
Source of Support: None, Conflict of Interest: None
Airtraq laryngoscope was designed to facilitate tracheal intubation in patients with either normal or difficult airways to provide high quality view of the glottis without the need to align the oral, pharyngeal, and tracheal axes. This study evaluates the usefulness of this new device in morbidly obese patients who are deemed to be at high risk of difficult intubation.
Forty morbidly obese (BMI>35 kg/m 2 ) adult patients with American Society Of Anaesthiologist physical status I-II were randomly divided into two groups (20 patients each). All patients were preoxygenated for 4 min then anesthetized with fentanyl (1-1.5 μg/kg), propofol (2-3 mg/kg), and succinylcholine (1 mg/kg). Thereafter, they were manually ventilated before tracheal intubation using Macintosh laryngoscope 'Group I' or Airtraq laryngoscope (Prodol Meditec S.A., Vizcaya, Spain) 'Group II'.
In the Macintosh group, two patients needed a stylet, one patient needed a bougie, and another four patients needed to switch to Airtraq, but in the Airtraq group only one patient needed to switch to Macintosh. In addition, the degree of difficulty of intubation in the two groups according to the sum of intubation difficulty score showed that four patients in the Macintosh group had high degree of difficulty against one patient in the Airtraq group. Hence, the visualization of the larynx and endotracheal intubation was better and easier with Airtraq laryngoscope than Macintosh laryngoscope.
The use of Airtraq laryngoscope is more suitable 'rapid, safe and successful' in tracheal intubation of high-risk morbidly obese patients.
Keywords: Airtraq, airway management, morbidly obese
|How to cite this article:|
El Sharkawy O, Ibrahim S. A comparative study on tracheal intubation using Airtraq laryngoscope versus Macintosh laryngoscope in morbidly obese patients. Menoufia Med J 2014;27:169-73
|How to cite this URL:|
El Sharkawy O, Ibrahim S. A comparative study on tracheal intubation using Airtraq laryngoscope versus Macintosh laryngoscope in morbidly obese patients. Menoufia Med J [serial online] 2014 [cited 2020 Feb 26];27:169-73. Available from: http://www.mmj.eg.net/text.asp?2014/27/1/169/132793
| Introduction|| |
Endotracheal intubation using direct laryngoscopy continues to be the 'gold standard' amongst all the techniques for isolating the airway .
Endotracheal intubation of obese patients may be difficult because of impaired oral manipulations resulting from fatty tissue accumulation in the cheeks and palate, hypertrophy of tonsils, upward shift of the larynx, and decreased mouth opening. In addition, difficult manipulations with a laryngoscope are likely to be associated with reduced mobility of the neck, whose circumference is markedly larger, and elevation of the thoracic cavity that hinders the maneuvers with a handle. The percentage of failures during intubations of obese patients has reached 13%. Direct laryngoscopy intubation attempts may also lead to a variety of traumatic mechanical complications because of excessive force used to visualize the laryngeal opening .
The failure to successfully intubate the trachea and secure the airway remains a leading cause of morbidity and mortality in the anesthetic and emergency settings. The curved laryngoscope blade described by Macintosh in 1943 remains the most popular device used to facilitate orotracheal intubation, both inside and outside the operating theater, and constitutes the gold standard .
The Airtraq laryngoscope (AL) is a new disposable intubation device developed to facilitate tracheal intubation in patients with normal or difficult airways. It is designed to provide a view of the glottis without alignment of the oral, pharyngeal, and tracheal axes. This is because of the exaggerated curvature of the blade and a series of lenses, prisms, and mirrors that transfer the image from the illuminated tip to a proximal viewfinder. A guiding channel on the right side of the blade acts as a conduit, holding and directing the endotracheal tube through the glottis opening when the vocal cords are visualized .
The fact that the Airtraq is easy to learn to use and simple to handle makes it a practical device in many situations where managing the airway is indicated. Its advantages over the Macintosh laryngoscope have been demonstrated in patients with an airway that it is difficult to manage with conventional laryngoscopes .
| Patients and methods|| |
Following written informed consent from patients, this study included 40 American Society Of Anaesthiologist physical status I-II morbidly obese patients, aged 18-50 years, scheduled for surgical procedures requiring tracheal intubation in Menoufia University Hospital during 2010-2011.
Exclusion criteria were risk factors for gastric aspiration and⁄or risk factors for difficult intubation (Mallampati class IV; thyromental distance<6 cm; interincisor distance<3.0 cm).
Patients were classified into two groups, '20 patients each'. All patients were preoxygenated for 4 min using facemask and then anesthesia was induced with fentanyl (1-1.5 μg/kg), propofol (2-3 mg/kg), and succinylcholine (1 mg/kg). Thereafter, they were manually ventilated with oxygen 100% before tracheal intubation using Macintosh laryngoscope or AL according to the group. After tracheal intubation, anesthesia was maintained with isoflurane in oxygen, fentanyl (0.5 μg/kg) boluses, and atracurium.
All data were recorded including demographic, anatomic [including Mallampati score [Figure 1]] , intubation criteria [including Cormack and Lehane grades [Figure 2] , cardiorespiratory criteria during intubation, and intubation difficulty criteria. The duration of the tracheal intubation attempt was measured as the time taken from insertion of the blade between the teeth until the endotracheal tube was placed through the vocal cords [Figure 3]. If intubation could not be established within 120 s, it was considered failure and shifted to other technique.
The intubation difficulty criteria were assessed according to the intubation difficulty score [Table 1]. This score is composed of seven parameters and each one is given a certain number 'score'. Then, these numbers were summed together and assessed as follows: 0=easy, 1-5=moderately difficult, and greater than 5=difficult or impossible intubation .
The results were analyzed to measure the SD and the significance was assessed using the χ2 -test for comparison between the two groups with respect to qualitative data and using the standard Student t-test for the difference between two means. P value less than 0.05 was considered significant.
| Results|| |
[Table 2] shows the demographic and anatomic data, with no significant differences between the two groups and no patients with the Mallampati score 4.
[Table 3] shows the intubation criteria with no patients classified as grade 4 Cormack and Lehane, but the score in grades 2 and 3 was significantly less in the Airtraq group; this means that AL gave better view. The intubation time was less in the Airtraq group with significant difference, and patients with postintubation trauma were less in number in the Airtraq group with significant difference; this means that it was more safe. Patients with failed intubation were less in number in the Airtraq group; this means that it was easy for intubation. Trauma was in the tongue, tonsillar pillars, and soft palate in the Airtraq group, but in the Macintosh group the injury was more in the lips and teeth. Four failed patients in the Macintosh group were switched to Airtraq that was successful in three patients only, and in the fourth patient laryngeal mask airway was used. Only one patient in the Airtraq group could not be intubated and the technique was switched to Macintosh.
[Table 4] shows the cardiorespiratory criteria during intubation with significant differences between the two groups, indicating calm and smooth intubation in the Airtraq group.
[Table 5] shows the intubation difficulty criteria in the two groups. In the Macintosh group, two patients needed a stylet, one patient needed a bougie, and another four patients needed to switch to Airtraq, but in the Airtraq group only one patient needed to switch to Macintosh. This means that intubation is easy in the Airtraq group.
[Table 6] shows the degree of difficulty of intubation in the two groups according to the sum of intubation difficulty score; it showed that four patients in the Macintosh group had high degree of difficulty against one patient in the Airtraq group.
|Table 6: The degree of difficulty of intubation in the two groups according to the sum of intubation difficulty score|
Click here to view
| Discussion|| |
The morbidly obese patients requiring intubation may present challenges, as obese patients frequently have limited mobility of temporomandibular and atlanto-occipital joints, a narrowed upper airway, and a shortened distance between the mandible and sternal fat pads. Direct laryngoscopy intubation attempts may also lead to a variety of traumatic mechanical complications because of excessive force used to visualize the laryngeal opening .
Obesity has been shown to be associated with increased risk of desaturation after induction of anesthesia. It may be possible to reduce this risk by increasing the volume of pressurized oxygen trapped in the lung before attempting tracheal intubation, but rapid intubation will certainly help to avoid desaturation .
The currently used laryngoscopes with straight (Magill) and bent (Macintosh) blades were introduced in the 1920s. Their modifications over time were not significant, and new designs were mainly to solve difficult intubation-related problems .
This new device for endotracheal intubation 'the Airtraq' is an optical laryngoscope that was launched in 2007 and combines the properties of a laryngoscope, rigid probe, or fiber-optic guide. It is a disposable device that visualizes the larynx through the eyepiece with an optical system. The endotracheal tube is placed in the Airtraq channel with a built-in light source (batteries last for 90 min of work) and an antifog system (to prevent misting over the distal lens in the oral cavity). For these reasons, this device should be set up 30 s before the intubation .
The greatest benefits in using the AL have been shown in patients with a pronounced limitation of cervical mobility and in those with distorted airway for anatomic reasons such as pregnant women and obese patients .
Many studies even in manikins show that the AL seems to be much quicker and easier to use than Macintosh laryngoscope even for inexperienced users, and intubation with the AL causes fewer traumatic complications than with Macintosh laryngoscope. However, Chalkeidis et al.  said that experienced anesthesiologists found no important difference, which could verify that everyday use of the Airtraq in routine airway management has no advantage over the traditional Macintosh laryngoscope, but the difference between the two groups (5.9 s) is statistically significant. It cannot be considered to be clinically significant; therefore, they believed that neither laryngoscopes have a clinically relevant advantage in terms of the time needed for intubation.
In this study, the tracheal intubation time was shorter with the AL than with the Macintosh laryngoscope, with a mean time of 12.1 ± 2.6 versus 18.1 ± 8.9 s, respectively. In addition, the Airtraq reduced the incidence of failure to intubate 'one patient in the Airtraq group versus four patients in the Macintosh group'. The Airtraq reduced the incidence of O 2 desaturation - 'O 2 saturation in Airtraq versus Macintosh was 97.9 versus 92.6%, respectively'. One patient in the Airtraq group suffered from O 2 desaturation below 88% versus three patients in the Macintosh group.
In this study, although Airtraq intubation was easier than Macintosh, the Airtraq was difficult to pass into the pharynx in five patients and intense pressure was often required to get the distal tip of the blade beyond the tongue. However, there was then an abrupt loss of resistance, as the tip of the blade finally passed into the oropharyngeal space and small crawling movement was needed to insert it.
With respect to external applied pressure, our study showed less application of external pressure in Airtraq '8 versus 16 cases' than in Macintosh. In addition, intense lifting pressure used was less in Airtraq '2 versus 18 cases' than in Macintosh. Our study is in agreement with the study by Maharaj et al.  in which they used the Airtraq for endotracheal intubation and found that the external applied pressure and intense lifting pressure were less in the Airtraq group rather than the Macintosh group.
The Visual Analog Score (VAS) 'of the degree of difficulty of face mask ventilation, introduction of laryngoscope, visualization of the larynx, and tracheal intubation' was found to be less in the Airtraq group - that is 'easier to deal with the airway': VAS of 32.10 ± 3.096 in the Airtraq group versus VAS of 46.50 ± 3.92 in the Macintosh group. This is in agreement with the study by Ndoko et al.  who found that VAS was 21.03 in the Airtraq group versus 39.02 in the Macintosh group.
In this study, two patients 'but not significant' in the Macintosh group needed two intubation attempts versus no patient in the Airtraq group; this is in agreement with the study by Tolon et al.  who found no statistically significantly difference between the two devices with respect to the number of intubation trials. In addition, Maharaj et al.  have reported nearly the same results in their study.
Thirteen patients in the Airtraq group were Cormack and Lehane grade 1, six patients were grade 2, and one patient was grade 3, but in the Macintosh group only four patients were Cormack and Lehane grade 1, eight patients were grade 2, and another eight patients were grade 3; however, no patients were grade 4 in both groups. In addition, the intubation difficulty score was increased in four patients in the Macintosh group with 'the mean score of 4.25±1.2' versus one patient in the Airtraq group with 'the mean score of 1.02±1.5'. These results mean that the use of Airtraq is significantly easier than that of Macintosh laryngoscope.
Hemodynamicaly, in this study it was found that the Airtraq resulted in less stimulation of the heart rate and blood pressure after tracheal intubation in comparison with the Macintosh laryngoscope. In addition, three patients suffered from bronchospasm in the Macintosh group versus one patient in the Airtraq group and there was neither regurge nor aspiration in either group. This study is in agreement with the study by Dhonneur et al.  who compared Airtraq with Macintosh laryngoscope in difficult situations and found that the respiratory events were common in the Macintosh group rather than in the Airtraq group.
| Conclusion|| |
The use of AL is more suitable in high-risk morbidly obese patients, achieves rapid and safe tracheal intubation, and causes less cardiorespiratory side effects.
| Acknowledgements|| |
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3]
[Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6]