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 Table of Contents  
ORIGINAL ARTICLE
Year : 2017  |  Volume : 4  |  Issue : 4  |  Page : 247-254

Intubation through air-Q and LMA-Excel using Shikani optical stylet in normal versus simulated difficult airway


Department of Anaesthesia and Surgical Intensive Care, Alexandria University, Alexandria, Egypt

Date of Submission12-Dec-2016
Date of Acceptance26-Feb-2017
Date of Web Publication11-Oct-2017

Correspondence Address:
Aly M.M. Ahmed
Department of Anaesthesia and Surgical Intensive Care, Alexandria University, 7 Al-Adham Street, Sanstefano, Alexandria
Egypt
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/roaic.roaic_120_16

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  Abstract 

Background
Unanticipated difficult mask ventilation and difficult intubation may cause serious complications, and airway management in such cases is challenging. Shikani seeing optical stylet (SOS) is a semirigid fiber-optic stylet used to manage difficult airway.
Aims
The current study aimed to assess and compare the intubation procedure through different intubating supraglottic devices (AIR-Q and LMA-Excel) while using the SOS in anesthetized patients with normal or simulated difficult airway scenario.
Patients and methods
This study was carried out on 120 adult female patients scheduled for elective abdominal hysterectomy under general anesthesia. All patients were intubated using the SOS through the supraglottic airways: 30 patients through Air-Q (group A-N), 30 patients through Air-Q while applying a neck collar (group A-D), 30 patients through LMA-Excel (group L-N), and 30 patients through LMA-Excel while applying a neck collar (group L-D). Evaluation parameters were as follows: airway score, hemodynamic parameters, leak pressure, laryngeal view grade, time to successful endotracheal tube insertion and number of attempts, and complications.
Results
The laryngeal view grade of the A-D group was significantly higher than that of the A-N group (P1) and L-D group (P4), and there was no significant difference when comparing group L-N with L-D (P2) and group A-N with L-N (P3). The mean successful time for intubation of group A-D (100.50±42.63 s) was significantly longer than that of group A-N (62±21.20 s) and group L-D (72±31.39 s), with a P value of 0.001. The number of intubation attempts ranged from 1 to 2 in groups A-N, L-N, and L-D, whereas 1 to 3 in group A-D.
Conclusion
The intubation through supraglottic airways (Air-Q and LMA-Excel) using the SOS is a feasible technique. The SOS can be used as an alternative apparatus for intubation through device when the flexible fiber-optic bronchoscope is not available. Laryngeal view grade is better with LMA-Excel when using the SOS. Intubation through LMA-Excel is easier than through Air-Q when using the SOS.

Keywords: Air-Q, LMA-excel, optical stylets, Shikani optical stylet, unanticipated difficult airway


How to cite this article:
Sharawy SS, El-Shafie SM, El-miteny SY, Ahmed AM. Intubation through air-Q and LMA-Excel using Shikani optical stylet in normal versus simulated difficult airway. Res Opin Anesth Intensive Care 2017;4:247-54

How to cite this URL:
Sharawy SS, El-Shafie SM, El-miteny SY, Ahmed AM. Intubation through air-Q and LMA-Excel using Shikani optical stylet in normal versus simulated difficult airway. Res Opin Anesth Intensive Care [serial online] 2017 [cited 2020 Jun 4];4:247-54. Available from: http://www.roaic.eg.net/text.asp?2017/4/4/247/216449


  Introduction Top


Airway management is at the core of care of unconscious anesthetized patients. Endotracheal intubation is the gold standard technique to secure a patent airway [1].

Unanticipated difficult mask ventilation and difficult intubation may cause serious complications [2]. Various guidelines are proposed for the management of the difficult airway either anticipated or unanticipated. The most recent and commonly used are the American Society of Anesthesiologists and the Difficult Airway Society guidelines [3],[4].

Supraglottic airway (SGA) devices are considered one of the cornerstones of modern airway management. In the early 1980s, the invention of the LMA is credited to Brain [5]. The Air-Q Intubating Laryngeal Airway (Cook gas LLC, Mercury Medical, Clearwater, FL, USA), invented by Daniel Cook and presented for practical use in 2004, can be used as a stand-alone device for maintenance of ventilation, oxygenation, and anesthesia as well as a conduit to aid endotracheal intubation [6]. Moreover, the LMA Classic Excel (eLMA; LMA North America, San Diego, California, USA) was introduced to anesthesia practice in 2009 [7], as an enhanced version of the classic LMA, designed to facilitate tracheal intubation with the aid of fiber-optic bronchoscopy [8].

Optical stylets are generally used as adjuncts to difficult direct laryngoscopy, can be used in both adults and children, and also can be used in unanticipated and anticipated difficult airways [9]. The Shikani optical stylet (SOS) (Clarus Medical, Minneapolis, Minnesota, USA) has a high-resolution, reusable, semirigid, malleable (can be bent up to 120°) fiber-optic cable housed within a stainless steel shaft, with an eyepiece located on the handle to allow indirect vision ([Figure 1]) [10].
Figure 1 Shikani seeing optical stylet

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This study aim was to assess and compare the intubation procedure through two intubating supraglottic airway devices (AIR-Q and LMA Classic Excel) while using the SOS in patients with normal airway or in simulated difficult airway scenario in anesthetized patients.


  Patients and methods Top


After approval of the local ethical research committee and having obtained written informed consent from all patients, 120 adult female patients scheduled for elective abdominal hysterectomy under general anesthesia were enrolled in the study. All patients were intubated using the SOS through the SGAs (AIR-Q or LMA-Excel) by the same operator. Patients were randomly divided into four equal groups: in groups A-N and A-D, intubation was done through Air-Q, but a cervical collar was applied to patients in group A-D, whereas in groups L-N and L-D, intubation was done through LMA-Excel, but a cervical collar was applied to patients in group L-D. Patients who were below 20 or above 50 years of age, had body weight of less than 50 or more than 100 kg, had American Society of Anesthesiologists score of more than III, had mouth opening of less than 2 cm, had airway score (AWS) of at least 5, and had emergency situations requiring rapid sequence induction were excluded.

Preoperatively, the AWS was calculated for each patient using El-Ganzouri multivariate index [11]; those enrolled in the normal groups had AWS 0, whereas those enrolled in the difficult group had AWS 1–4. On arrival to the operating room, standard monitoring was applied, and an intravenous cannula was inserted, followed by the administration of 0.01 mg/kg atropine and 2 mg midazolam 5 min before induction of anesthesia. Before induction of anesthesia, in the selected patients in the difficult groups, rigid cervical collar was applied to fit tightly without impairing ventilation and keeping the neck in a neutral position [12].

While preoxygenating with 100% oxygen by face mask, anesthesia was induced by intravenous fentanyl 1 μg/kg, propofol 2 mg/kg, and atracurium 0.5 mg/kg. Intermittent positive pressure ventilation for at least 3 min was carried out using isoflurane (minimum alveolar concentration=1) in 100% oxygen, and the proper-size semi-inflated SGA device was inserted by the classical method. The leak pressure was measured by closing the expiratory valve, with the oxygen flow at 5 l/min, stopping ventilation and keeping the patient apneic.

After adequate oxygenation, the patient was disconnected from the ventilator and the SGA adaptor removed. The ETT-SOS assembly was inserted through the airway tube so that the tip of the assembly just exits through the distal opening of the device to detect the laryngeal view grade (∼16 cm mark of the ETT at the adaptor-less breathing shaft).

Laryngeal view grade ranges from 1 to 5: grade 1–only larynx was seen, grade 2–larynx and the posterior surface of epiglottis were seen, grade 3–larynx and anterior tip of epiglottis were seen with less than 50% visual obstruction of larynx, grade 4–epiglottis down folded and its anterior surface was seen with more than 50% visual field obstruction, and grade 5–complete down folding of epiglottis and the larynx could not be seen directly [13].

Under direct vision, the tip of the ETT was introduced between the vocal cords inside the trachea, by railroading the ETT off the SOS while rotating it anticlockwise as the SOS is removed. The ETT cuff was then inflated, and the circuit was reconnected with the ETT. The correct position of ETT was confirmed by square wave end-tidal capnogram with positive pressure ventilation. The used supraglottic airway device with the ETT inside was left in place throughout the operation with the device cuff deflated.

If intubation was unsuccessful at the first attempt or if desaturation was noted (defined as SpO2<93%), the intubation attempt was stopped and the lungs ventilated with an oxygen-volatile anesthetic mixture for 3 min, followed by a second attempt. If intubation was unsuccessful after two attempts, the cervical collar was removed and the patient was ventilated with an oxygen-volatile anesthetic mixture for 3 min, followed by the last trial through the SGA. A total of three failed attempts of insertion despite minor airway interventions were rated as failure, and the patient was intubated by direct laryngoscopy using the Macintosh blade laryngoscope (Mercury Medical, Clearwater, FL, USA). SPSS (IBM corp., USA). Anesthesia was maintained with isoflurane 1 minimum alveolar concentration in 100% oxygen combined with intermittent boluses of intravenous atracurium to maintain adequate muscle relaxation and intermittent positive pressure ventilation. At the end of operation, patients were extubated (ETT–SGA assembly removed together).

Heart rate (HR), systolic arterial blood pressure, and arterial oxygen saturation (SpO2) were measured preoperatively after induction of anesthesia, after SGA insertion, after ETT insertion, and 5 min after ETT insertion. Leak pressure, laryngeal view grade, time to successful ETT insertion, number of attempts of insertion of ETT, and the incidence of any complications were measured.

Statistical analysis

The sample size was approved to be sufficient by the Department of Statistics, High Institute of Public Health, Alexandria University, Alexandria, Egypt. Data were fed to the computer and analyzed using IBM SPSS software, version 20.0. Data were represented as mean±SD. Statistical comparison between two groups was done using student t-test for quantitative data. Analysis of variance was done for comparing between quantitative variables of more than two groups, and paired t-test was done to compare between quantitative variables in two periods. χ2-test was done for categorical data, and Kruskal–Wallis test was used to compare between more than two groups of abnormally quantitative variables. Wilcoxon signed ranks test was done to compare between two periods for abnormally quantitative variables, and Spearman coefficient to correlate between two quantitative variables.


  Results Top


Patients’ demographic data were not significantly different. AWS in the two normal groups (A-N and L-N) was 0, whereas in the two difficult groups (A-D and L-D), AWS ranged from 1 to 4 ([Table 1]).
Table 1 Comparison between the four studied groups regarding demographic data and airway score

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There were no statistically significant differences between the four groups regarding HR, systolic arterial blood pressure, and SpO2. However, in case of HR, the preoperative values were significantly lower in each group when compared with other periods ([Figure 2],[Figure 3],[Figure 4]).
Figure 2 Comparison of heart rate. ETT, endotracheal tube; SGA, supraglottic airways

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Figure 3 Comparison of systolic arterial pressure. ETT, endotracheal tube; SAP, systolic arterial blood pressure; SGA, supraglottic airways

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Figure 4 Comparison of oxygen saturation. ETT, endotracheal tube; SGA, supraglottic airways

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There was no statistically significant difference between the groups in leak pressure, but it was slightly higher in the two Air-Q groups than that in the LMA-Excel groups. The laryngeal view grade of the A-D group was significantly higher than that of the A-N group (P1) and that of the L-D group (P4), and there was no significant difference when comparing group L-N with L-D (P2) and group A-N with L-N (P3) ([Table 2]).
Table 2 Comparison of leak pressure and laryngeal view grade

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The mean successful time for intubation of group A-D (100.50±42.63 s) was significantly longer than that of group A-N (62±21.20 s), with a P value of less than 0.001, and that of group L-D (72±31.39 s), with a P value of 0.001 ([Figure 5]). Regarding the number of intubation attempts, it ranged from 1 to 2 in groups A-N, L-N, and L-D, whereas in group A-D, it ranged from 1 to 3, which was significantly higher ([Figure 6]).
Figure 5 Comparison of time to successful insertion of endotracheal tube (ETT)

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Figure 6 Comparison of number of endotracheal tube (ETT) insertion attempts

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When using the Spearman coefficient to search for a correlation between the laryngeal view grade and the time for successful ETT insertion in the 120 patients of the study, a positive correlation was found, with a P value of less than 0.001 and r of 0.407 (positive r). Therefore, the higher the grade of the laryngeal view, the longer is the duration to successful intubation ([Figure 7]). There was no statistically significant difference between the four groups regarding incidence of complications ([Table 3]).
Figure 7 Correlation between laryngeal view grade and time of successful insertion of endotracheal tube (ETT)

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Table 3 Comparison of complications

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  Discussion Top


Our main finding is that the Air-Q and LMA-Excel can both be used as a conduit for ETT insertion using the SOS. Air-Q is widely used as a conduit for intubation, whereas LMA-Excel is a relatively newer SGA from the LMA family with some enhanced unique features. To our knowledge, no study has been done to compare the intubation procedure through Air-Q and LMA-Excel using the SOS. Also, no study was conducted that used the SOS for intubation through any SGA. All the studies that assessed SGA devices as a conduit for ETT used a flexible fiber-optic bronchoscope, or the intubation procedure was done blindly.

In the present study, no significant difference was found in leak pressure between the groups, whereas the Air-Q was found to have a slightly higher sealing pressure, may be owing to its unique features: an anterior curve of the airway tube, mask ridges that may improve the transverse stability of the bowl and support the lateral cuff seal, and a higher posterior heel height which may improve the seal at the base of the tongue. Furthermore, reusable Air-Q is constructed from silicone, which is assumed to conform to the supraglottic structures better than the single-use PVC [14]. Similarly, Abdel-Halim et al. [15] and Galgon et al. [14] found that the leak pressure of Air-Q was 26.400±2.176 and 30±7 cmH2O, respectively.

In the current study, it was observed that the laryngeal view grade was statistically significantly higher in the A-D group when compared with groups A-N and L-D. However, there was no statistical significant difference among groups A-N, L-N, and L-D. This better laryngeal view grade in the LMA-Excel groups may be because of the characteristic features of the LMA-Excel, increased angle between the airway tube and the mask bowl, and the presence of the epiglottic elevation bar (elevate the epiglottis away from the laryngeal view as the SOS–ETT assembly exit the laryngeal tube). The most commonly encountered laryngeal view in the 120 patients of this study is grade 1 (47.5%), whereas the least commonly encountered is grade 5 (1.66%, only two patients in group A-D). Similarly, El-Ganzouri et al. [11] recorded a mean laryngeal view grade of 1.8±1.3 with Air-Q, and Pandey et al. [13] found that grade 1 laryngeal view was the commonly encountered (41 of 60 patients) one with Air-Q.

The mean time of ETT insertion in the four groups (A-N, A-D, L-N, and L-D) was 62±21.20, 100.50±42.63, 60.5±22.36, and 72±31.39 s, respectively. Mean time of ETT insertion was significantly longer in group A-D when compared with groups A-N and L-D. Jagannathan et al. [16] found a comparable time for intubation of 62.5 (47.9–77) s through the Air-Q with flexible bronchoscope.

When using the Spearman coefficient to search for a correlation between the time for successful ETT insertion and laryngeal view grade in the 120 patients of this study, it was found that there is a positive correlation with a P value of less than 0.001 and r of 0.407 (positive r). So, the higher the grade of the laryngeal view, the longer is the duration to successful intubation. Lee et al. [17] found similar correlation when comparing the intubation between the Air-Q and LMA-Excel.

Number of attempts of successful insertion of ETT through SGA were statistically higher in group A-D when compared with groups A-N and L-D, with a first-attempt success rate in groups A-N, A-D, L-N, and L-D of 90.0, 53.3, 93.3, and 83.3% respectively. There were two cases in group A-D that needed a third intubation attempt. There were three cases of failed intubation, which were excluded from the study, two of them in group A-D and one in group L-D, with an overall success rate of 97.5%. In accordance with this study, Turkstra et al. [18] showed 91.3% success rate of Shikani optical stylet. In addition, Mihai et al. [19] found in their meta-analyses study, overall success of 94.9% with Shikani optical stylet. But both studies used the SOS as a stand-alone device. Also, Lee et al. [17] found that the intubation success rates with the Air-Q and LMA Classic Excel were 100 and 87.8%, respectively.

Regarding complications that occurred in this study, five patients got excessive secretions (three in group A-D and two in group L-D), seven patients got sore throat (two in group A-N and four in group A-D, one in group L-N, and two in group L-D), only one patient got blood-streaked mucous in group A-D, and there were no cases of laryngeal spasm. The relatively high incidence of sore throat and excessive secretions may be because of leaving the SGA in place even after endotracheal intubation throughout the operation. Similar to our study, Galgon et al. [14] reported that postoperative sore throat was common with the Air-Q (46% of the 52 patients) when used for maintenance of anesthesia in adults. Moreover, Jagannathan et al. [16] found that of 50 patients who were ventilated with Air-Q, no patient had complications of laryngospasm or blood staining, and two patients complained of postoperative cough/dysphonia.


  Conclusion Top


The intubation through SGAs (Air-Q and LMA-Excel) using the SOS is a feasible technique. The SOS can be used as an alternative apparatus for intubation through device when the flexible fiber-optic bronchoscope is not available. Laryngeal view grade is better with LMA-Excel when using the SOS. Intubation through LMA-Excel is easier than through Air-Q when using the SOS.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflict of interest.

 
  References Top

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    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7]
 
 
    Tables

  [Table 1], [Table 2], [Table 3]



 

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