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Cover page of the Journal of Health Sciences


 
 Table of Contents  
ORIGINAL ARTICLE
Year : 2017  |  Volume : 10  |  Issue : 1  |  Page : 84-89

Comparison of the glottic view during intubation using Airtraq and Macintosh laryngoscopes in adult patients undergoing surgeries under general anesthesia with a simulated cervical spine immobilization: A 1-year hospital-based randomized controlled trial


Department of Anesthesiology, KLES Dr. Prabhakar Kore Hospital and Medical Research Centre, Belagavi, Karnataka, India

Date of Web Publication18-Jan-2017

Correspondence Address:
Dr. Avinash Rayavarapu
Department of Anesthesiology, KLES Dr. Prabhakar Kore Hospital and Medical Research Centre, Belagavi, Karnataka
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/2349-5006.198596

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  Abstract 

Background and Objectives: The present study was undertaken to compare the glottic view during intubation using Airtraq and Macintosh laryngoscopes in adult patients undergoing surgeries under general anesthesia with a simulated cervical spine immobilization.
Methods: This 1-year randomized clinical study was conducted between January 2015 and December 2015 on 60 American Society of Anesthesiologists Grade I and II patients of either gender, aged between 18 and 60 years. The study population was randomly divided into two groups. Group A (n = 30): intubation performed using Airtraq laryngoscope. Group L (n = 30): intubation performed using Macintosh laryngoscope.
Results: In the present study, 76.67% of patients in Group A had a Cormack-Lehane Grade 1 view of glottis compared to 13.33% in Group L. While most of the patients (56.67%) in Group L had Cormack-Lehane Grade 2 view of glottis compared to 23.33% in patients of Group A. Thus, Airtraq laryngoscope had better Cormack-Lehane grade of glottic view with P = 0.001. It was observed in our study that the mean heart rate, mean systolic blood pressure, mean diastolic blood pressure, and mean arterial pressure were higher in Group L compared to Group A at 1 min, 3 min, and 5 min intervals.
Conclusion: These findings suggest that tracheal intubation with Airtraq offers better view of glottis with minimal changes in hemodynamic parameters in patients with a simulated cervical spine immobilization compared to Macintosh laryngoscope.

Keywords: Airtraq video laryngoscope, cervical spine immobilization, Macintosh laryngoscope


How to cite this article:
Rayavarapu A, Dhorigol M G. Comparison of the glottic view during intubation using Airtraq and Macintosh laryngoscopes in adult patients undergoing surgeries under general anesthesia with a simulated cervical spine immobilization: A 1-year hospital-based randomized controlled trial. Indian J Health Sci Biomed Res 2017;10:84-9

How to cite this URL:
Rayavarapu A, Dhorigol M G. Comparison of the glottic view during intubation using Airtraq and Macintosh laryngoscopes in adult patients undergoing surgeries under general anesthesia with a simulated cervical spine immobilization: A 1-year hospital-based randomized controlled trial. Indian J Health Sci Biomed Res [serial online] 2017 [cited 2019 Jul 16];10:84-9. Available from: http://www.ijournalhs.org/text.asp?2017/10/1/84/198596


  Introduction Top


Conventionally, Macintosh laryngoscope is used for tracheal intubation. However, with cervical spine immobilization, it is more difficult to visualize the larynx using the Macintosh laryngoscope.[1],[2]

This has prompted the development of newer alternatives to Macintosh laryngoscope to improve the glottic visualization and ease of intubation in patients with cervical spine immobilization such as Airwayscope, Glidescope, C-MAC, and Airtraq.[2],[3],[4],[5] The Airtraq (AirTraq, Prodol Meditec, Vizcaya, Spain) is an intubation device that has been developed to aid laryngoscopy. It provides a high quality glottic view eliminating the need for alignment of the oral, pharyngeal, and laryngeal axis.[5]

The unique curving blade of the Airtraq® is designed to fit the oropharyngeal anatomy. It possesses considerable advantages in the setting of cervical spine immobilization[5] when direct laryngoscopy is difficult or not recommended.[6] The Airtraq facilitates tracheal intubation with the neck in neutral position, which is similar to the neck position maintained by a rigid cervical collar.[7] However, a rigid cervical collar in combination with forehead strapping and manual in-line stabilization (MILS) virtually obliterates even the small neck movements which normally facilitate airway insertion.[8]

There are limited number of studies reported in literature comparing glottic visualization obtained by Airtraq and Macintosh laryngoscopes. Hence, an attempt is made to compare the glottic visualization between Macintosh laryngoscope and Airtraq video laryngoscope in patients with a simulated cervical spine immobilization posted for surgery under general anesthesia based on Cormack-Lehane grading and also to evaluate the hemodynamic changes in both the groups

Aims and objectives

The primary objective of the study is to compare the glottic visualization by Cormack-Lehane grading between Macintosh laryngoscope and Airtraq video laryngoscope in patients with a simulated cervical spine immobilization posted for surgeries under general anesthesia. The secondary objective is to compare the hemodynamic changes in both the groups.


  Design and Methodology Top


The present study was conducted in the Department of Anaesthesiology, KLES Dr. Prabhakar Kore Hospital and Medical Research Centre, for 1 year from January 2015 to December 2015. Patients with American Society of Anesthesiologists (ASA) physical status I and II, of either gender aged between 18 and 60 years, posted for elective surgeries under general anesthesia with oral endotracheal intubation were included in the study. Patients with risk of pulmonary aspiration of gastric contents, pregnant women, and cervical spine pathology, and patients with body mass index (BMI) >30 were excluded from the study.

Before the commencement, the ethical clearance was obtained from the Institutional Ethics Committee, Jawaharlal Nehru Medical College, Belagavi. The patients posted for elective surgeries in supine position, under general anesthesia, in whom tracheal intubation was indicated, and fulfilling selection criteria were briefed about the nature of the study and interventions and a written informed consent was obtained.

Demographic data of the patients such as name, age, sex, and history were obtained through an interview. Visualization of pharyngeal structures and larynx as per Cormack and Lehane grading and hemodynamic response to endotracheal intubation with Airtraq video laryngoscope and Macintosh laryngoscope was analyzed. These findings were recorded on predesigned and pretested pro forma. The physical and medical examinations were conducted. Routine investigations such as complete blood picture, mini renal profile, electrocardiogram (ECG), and chest X-ray were done. Patients were randomized based on computerized generated randomization into two groups. Group L (n = 30) - Macintosh group and Group A (n = 30) - Airtraq group.

Anesthetic techniques were standardized for all patients. Preanesthetic checkup was done 1 day before the surgery. Before shifting to the operation theater, overnight fasting status was confirmed, intravenous (IV) access was obtained with 18-gauge IV cannula. Standard monitoring devices were attached before induction of anesthesia, including noninvasive arterial blood pressure, ECG, and pulse oximeter saturation. After 5 min of preoxygenation with a face mask (for adequate oxygen reserve), patients were premedicated with injection glycopyrollate −0.005 mg/kg, midazolam −0.05 mg/kg, pentazocine −0.5 mg/kg, and general anesthesia was induced with thiopentone-5 mg/kg and vecuronium - 0.1 mg/kg. A rigid cervical immobilization collar was applied. The patients were allocated randomly to tracheal intubation with an Airtraq (Group A) or Macintosh laryngoscope (Group L). The randomization was based on computer-generated randomization codes. Three minutes after vecuronium administration, tracheal intubation was performed using one of the study devices.

In patients allocated to Group A, appropriate size of Airtraq based on the size of endotracheal tube (ETT) to be used was selected. Light was turned on, and time was given for activation of the antifogging system. Appropriate-sized ETT with cuff fully deflated was lubricated and placed into the lateral channel of the Airtraq. The tip of the ETT was aligned with the end of the lateral channel. Airtraq was lubricated without contacting the lens. The Airtraq blade was inserted into the mouth in the midline, over the center of the tongue, the tip positioned in the valecula, and the laryngoscope was lifted straight up to expose the glottis. Once the view of the glottis had been optimized, the tracheal tube was passed through the vocal cords, tracheal tube was held in place, and the device removed. The ETT was connected to closed circuit. Intubation was confirmed by square wave capnography.

In patients belonging to Group L, Macintosh laryngoscope no. 3 or no. 4 was used to obtain the best possible view of the glottis. Tracheal tubes with 7.5 and 8.5 mm internal diameter for women and men, respectively, were used. During the procedure, heart rate and mean blood pressure at baseline, 1, 3, and 5 min after the intubation were recorded. The best glottic view obtained in both groups was noted, according to Cormack-Lehane grading.

Whenever the first attempt for intubation failed, the intubation attempt was terminated and a second attempt was made after mask ventilation for 1 min. In the event of failed second attempt, the rigid cervical collar was removed and the patients were intubated under direct vision using a conventional laryngoscope. No other medications were administered, or procedures performed, during the 5-min data collection period after was removed and the patients were intubated under direct vision using a conventional laryngoscope. No other medications were administered tracheal intubation. Subsequent management was left to the discretion of the anesthetist providing care for the patient.

Cormack and Lehane grading was done as below:

  • Grade I: Visualization of entire vocal cords
  • Grade II: Visualization of posterior part of the laryngeal aperture
  • Grade III: Visualization of epiglottis
  • Grade IV: No glottic structure seen.


Secondary end points were hemodynamic profiles of both the groups including systolic blood pressure, diastolic blood pressure, mean arterial pressure, and heart rate recorded at baseline 1, 3, and 5 min after intubation.

Statistical methods

The data were analyzed using IBM SPSS Statistics 20.0 (IBM Corp. Released 2011. IBM SPSS Statistics for Windows, Armonk, NY: IBM Corp.). The categorical data were expressed in terms of rates, ratios, and percentages and the continuous data were expressed as mean ± standard deviation. Significance was tested with allowable error of 5%. Independent sample t-test was used to find the significance of study parameters on continuous scale between two groups. Chi-square test was used to find association between the classes of variables. A probability value (P ≤ 0.050) at 95% confidence interval was considered as statistically significant.


  Results Top


In this study, the mean age (38.10 ± 9.84 vs. 34.40 ± 12.56 years P = 0.201), mean weight (66.50 ± 7.51 vs. 64.07 ± 4.08 kg; P = 0.126), mean height (165.30 ± 6.83 vs. 162.40 ± 6.03 cm; P = 0.080), and BMI (24.30 ± 2.05 vs. 24.48 ± 1.76 kg/m2 ; P = 0.705) were comparable in Group L and Group A [Table 1]. In the present study, 53.33% of the patients in Group L were males compared to 46.67% in Group A [Table 1]. However, this difference was statistically not significant (P = 0.301).
Table 1: Clinical characteristics of the study population


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In the present study, 66.67% of the patients in Group L had ASA status 1 compared to 73.33% in Group A [Table 1]. However, this difference was statistically not significant (P = 0.573). In this study, the Mallampatti grades of patients in Group L and Group A were almost similar with no statistically significant difference. In this study, significantly higher number of patients in Group A (76.67%) had Cormack-Lehane Grade 1 compared to patients in Group L (13.33%) [Table 2]. This difference was statistically significant (P = 0.001).
Table 2: Comparison of Cormack-Lehane grading


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In this study, mean pulse rate at baseline was comparable in Group L and A (P = 0.406) while at 1 min (85.60 ± 7.63 vs. 79.30 ± 7.56/min; P = 0.002 at 1 min), 3 min (81.20 ± 7.41 vs. 75.70 ± 7.07/min; P = 0.005), and 5 min intervals (76.30 ± 7.43 vs. 71.30 ± 7.18/min; P = 0.011), it was significantly higher in Group L compared to Group A [Graph 1].



In the present study, mean systolic blood pressure at baseline was comparable in Group L and A (P = 0.125); however, at 1 min interval, the mean systolic blood pressure was significantly high in Group L (142.40 ± 9.32 mm Hg) compared to Group A (134.40 ± 10.16 mm Hg) (P = 0.002) Similar statistically significant differences were noted at 3 min interval (136.90 ± 8.86 vs. 129.30 ± 9.66 mm Hg; P = 0.003) and 5 min interval (131.10 ± 9.11 vs. 125.10 ± 9.35 mm Hg; P = 0.014), respectively [Graph 2].



In this study, mean diastolic blood pressure at baseline and 5 min interval was comparable in Group L and A (P = 0.242); however, at 1 min interval, the mean diastolic blood pressure was significantly high in Group L (85.10 ± 4.81 mm Hg) compared to Group A (81.60 ± 4.83 mm Hg) (P = 0.006). Similar statistically significant differences were noted at 3 min interval (80.60 ± 4.17 vs. 77.00 ± 5.12 mm Hg; P = 004), respectively [Graph 2].

In the present study, mean of arterial pressure at baseline was comparable in Group L and A (P = 0.171); however, at 1 min interval, the mean arterial pressure was significantly high in Group L (104.20 ± 5.96 mm Hg) compared to Group A (99.20 ± 6.13 mm Hg) (P = 0.002) and similar statistically significant differences were noted at 3 min interval (99.30 ± 5.27 vs. 94.60 ± 6.17 mm Hg; P = 0.003) and 5 min (94.30 ± 5.29 vs. 90.90 ± 5.89 mm Hg; P = 0.022), respectively [Graph 2].

In the present study, no complications were noted in both the groups.


  Discussion Top


During the airway management procedures, the degree of cervical spine motion varies according to the intubation techniques.[9],[10],[11] Oral intubation with neck immobilization is an accepted feasible method in trauma patients suspected of having cervical injuries.[12] However, this neck immobilization has been shown to worsen the laryngoscopic views and decrease the interincisor distance.[1]

The MILS is a widely accepted neck immobilization technique.[13] The reports that this method increases the risk of subluxation[14],[15] and the requirement of a method-acknowledged assistant makes the value of this method doubtful. A Philadelphia cervical collar is used for neck immobilization because patients with suspected cervical spine injuries are transported to the operating room with this device and removing this device can cause considerable spinal movement.

The development of laryngoscopes that reduce tracheal intubation difficulty in these patients would represent a real advance. The Airtraq has demonstrated promise in a number of settings including simulated easy[7],[16],[17],[18] and difficult[7],[16],[17],[18] laryngoscopy and in patients at lower[19] and higher risk[5],[20],[21] for difficult tracheal intubation.

The Airtraq (AirTraq, Prodol Meditec, Vizcaya, Spain) is an intubation device that has been developed to aid laryngoscopy. The curvature of the Airtraq blade and the special internal arrangement of the optical components allow visualization of the glottic plane without alignment of the oral, pharyngeal, and laryngeal axis.[22]

The present 1-year hospital-based randomized control trial was undertaken in the Department of Anaesthesiology, KLES Dr. Prabhakar Kore Hospital and Medical Research Centre, from January 2015 to December 2015 for1 year. A total of sixty patients posted for surgeries under general anesthesia were randomized based on computerized generated randomization table into two groups of 30 each as Group L (Patients in this group underwent tracheal intubation using Macintosh laryngoscope) and Group A (patients in this group underwent tracheal intubation using Airtraq video laryngoscope).

There was no significant difference in the demographic profile and airway characteristics of patients in the two groups.

In the present study, 76.67% of patients in Group A had a Cormack-Lehane Grade 1 view of glottis compared to 13.33% in Group L. Most of the patients (56.67%) in Group L had Cormack-Lehane Grade 2 view of glottis compared to 23.33% in patients of Group A. Thus, Airtraq laryngoscope significantly reduced the Cormack-Lehane grade of glottic view with P = 0.001. These findings are consistent with a study by Koh et al.[23] They assessed that the percentage of glottic opening (POGO) score was significantly greater in Group A (84 ± 20%) than in Group L (6 ± 11%). However, Philadelphia cervical collar was used in the study.

Similar results were observed in a study conducted by Tolon et al.[24] comparing the use of Macintosh laryngoscope and Airtraq in patients with cervical spine immobilization. They found that 90% of the patients intubated with the Airtraq laryngoscope had a Grade I Cormack and Lehane glottic view and 10% had Grade 2, compared with 50% Grade 1 view, 35% Grade 2 view, and 15% Grade 3 view in the Macintosh laryngoscope group. The results of the present study are also similar to the study by Bhandari et al. comparing Airtraq and Macintosh laryngoscopes for tracheal intubation with better POGO scores in the Airtraq group (100%) versus 67.5% in the Macintosh group, P < 0.001.

The Airtraq has advantages in both limited mouth opening and poor laryngeal view settings.[5],[25] Exaggerated curvature of the Airtraq blade eliminates the requirement of neck extension to align the oral, pharyngeal, and laryngeal axis. The internal arrangement of the high-definition optical components including a series of lenses, prisms, and mirrors with antifogging system transfer the image from low temperature illuminated tip to the proximal view finder, giving a high quality and wide angle view of glottis, surrounding structures, and the tip of the ETT.[23]

During administration of general anesthesia, laryngoscopy and tracheal intubation are considered most critical events as they trigger transient but marked sympathoadrenal response which can be detrimental in patients particularly with underlying cardiac diseases.[26]

It was observed in our study that the mean heart rate, mean systolic blood pressure, mean diastolic blood pressure, and mean of mean arterial pressure were higher in Group L compared to Group A at 1 min, 3 min, and 5 min intervals. These findings suggest that tracheal intubation with Airtraq offers better view of glottis with minimal changes in hemodynamic parameters in patients with a simulated cervical spine immobilization compared to Macintosh laryngoscope.

The hemodynamic findings in our study were comparable to those described by Tolon et al.,[24] in their comparative study between the use of Macintosh laryngoscope and Airtraq in patients with cervical spine immobilization. There was a statistically significant increase in both heart rate and mean arterial pressure in Macintosh group than Airtraq group.

This could be due to exaggerated anatomical curvature of the blade of Airtraq laryngoscope which does not require alignment of oral, pharyngeal, and laryngeal axis with less lifting force required during laryngoscopy and lesser trauma caused during intubation.

Koh et al.[23] reported that mean blood pressure before intubation was significantly decreased as compared with the baseline value in both groups. Mean blood pressure after intubation was also decreased compared to baseline value in both the groups. Heart rate after intubation was significantly increased as compared with those of baseline and before intubation in both groups which was consistent with the present study. However, in contrast to the findings of the present study, there were no significant differences between the two groups, which can be due to the usage of remifentanil throughout the procedures which has been proved to prevent the hemodynamic changes during airway management.[27],[28],[29]

An important potential advantage of the Airtraq is that it is a single-use device, reducing the chance of prion transfer.[23],[28],[29] These concerns arise from the difficulties in ensuring that all proteinaceous material have been removed from reusable laryngoscope blades during cleaning and sterilization.[18],[29]

There limitations in our study are anesthesiologist was not blinded to the devices used, the laryngoscopic glottic view grading was subjective in nature, and the results may also vary among anesthetists with differing expertise in the use of the devices.


  Conclusion Top


The Airtraq videolaryngoscope produced a superior laryngeal view (CL grading) over the Macintosh laryngoscope during intubation in patients with a rigid cervical collar with lesser variation in hemodynamic parameters.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

 
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