|Year : 2019 | Volume
| Issue : 4 | Page : 399-407
Comparison between three supraglottic airway devices as conduits for fiber-optic tracheal intubation
Salwa H Waly, Yasser M Nasr, Nahla M Amin
Department of Anesthesia and Surgical Intensive Care, Faculty of Medicine, Zagazig University, Zagazig, Egypt
|Date of Submission||26-Dec-2018|
|Date of Acceptance||18-Mar-2019|
|Date of Web Publication||06-Jan-2020|
MD Salwa H Waly
17 El Khashab Street Behind El Mabarra Hospital, Al Sharkia, Zagazig 44511
Source of Support: None, Conflict of Interest: None
Background Securing the airway is a major task for anesthesiologists. Supraglottic airway devices (SADs) are widely used nowadays. Fiber-optic endotracheal intubation (ETT) plays an important role in difficult-to-manage airways. The general purpose of a conduit is to provide a clear protected pathway for the expensive, sensitive, and fragile fiber-optic cable.
Aimof the work To compare between three SADs as conduits for fiber-optic tracheal intubation.
Patients and methods A prospective, randomized study involving 81 adult patients (American Society of Anesthesiologists I or II), of both sexes who were allocated into three groups (27 patients each): Air-Q group (group Q), intubating laryngeal mask airway (ILMA) group (group L) or I-Gel group (group G). Fiber-optic ETT through SADs was performed. The number of attempts and duration of insertion of SAD, laryngeal view grading, number of attempts, and duration of insertion of ETT were assessed. Complications were recorded.
Results The ease and number of attempts to insert SADs showed no statistically significant differences. The duration of insertion of SADs was statistically favoring the Air-Q intubating laryngeal airway (13±3 s), compared with ILMA (19±4 s) and I-Gel (18±3 s). The fiber-optic grading of laryngeal view through SADs also favored group Q compared with other groups. Number of attempts to insert ETT through SADs showed no statistically significant differences between groups. The duration of insertion of the ETT via fiber-optic bronchoscopic through the SADs showed highly statistically significant difference (P<0.001) in favor of group Q (35±5 s) as compared with group L (45±7 s) and group G (42±6 s). Blood stains on SADs just after removal from patients’ airways and sore throat in the first postoperative hour showed no statistically significant difference between groups.
Conclusion Air-Q, ILMA, and I-Gel were useful conduits for fiber-optic ETT. Air-Q intubating laryngeal airway provides better visualization of the glottis and shorter time for insertion of both the device and the ETT than ILMA and I-Gel.
Keywords: Air-Q laryngeal mask airway, fiber-optic intubation, I-Gel, intubating laryngeal mask airway
|How to cite this article:|
Waly SH, Nasr YM, Amin NM. Comparison between three supraglottic airway devices as conduits for fiber-optic tracheal intubation. Res Opin Anesth Intensive Care 2019;6:399-407
|How to cite this URL:|
Waly SH, Nasr YM, Amin NM. Comparison between three supraglottic airway devices as conduits for fiber-optic tracheal intubation. Res Opin Anesth Intensive Care [serial online] 2019 [cited 2020 Apr 6];6:399-407. Available from: http://www.roaic.eg.net/text.asp?2019/6/4/399/275134
| Introduction|| |
Difficult airway is a major cause for mortality in anesthesia . The supraglottic airway devices (SADs) were primarily designed to be inserted superior to the level of the vocal cord for ventilation during spontaneous or intermittent positive pressure ventilation . Thereafter, it was found that SADs can provide a possible alternative technique to endotracheal intubation (ETT) owing to the easiness of their blind insertion and the effectiveness of positive pressure ventilation delivered through them during elective surgery. Moreover, they can be used to manage cases of difficult airway and during cardiopulmonary resuscitation . LMA classic is now included in Difficult Airway Society guidelines for unanticipated difficult intubation . The intubating laryngeal mask airway (ILMA) was found to cause less hemodynamic response than rigid laryngoscope in normal airways, thereby, it can be used in patients with unstable cardiovascular conditions .
The Air-Q intubating laryngeal airway (ILA) (Cook gas LLC; Mercury Medical, Clearwater, Florida, USA) is a supraglottic airway which might be used as a primary airway or as an aid for ETT. The Air-Q ILA has some special features that allow it to become a better alternative to the LMA classic . These features are related to both its breathing tube being shorter and wider and to the removable connector that allows the placement of a standard tracheal tube .
The ILMA (Fastrach, iLMA; Teleflex Medical Europe Ltd., IDA Business and Technology Park, Dublin Road, Athlone, Co Westmeath, Ireland) is a supraglottic device that has a unique design enabling it to be used to facilitate intubation in addition to being used as an effective ventilatory device. It has a rigid curved airway tube and the air-filled cuff with epiglottic elevator that facilitates blind intubation ,. It can also be used as a conduit for fiber-optic endoscopic intubation .
I-Gel (Intersurgical, Wokingham, UK) is a SAD with no inflatable cuff. It is made from a soft, gel-like, and transparent thermoplastic elastomer (a polymer that displays rubber-like elasticity) that acts as a noninflatable seal which is a mirror impression of the supraglottic anatomy. It has several other useful design-related advantages including a gastric channel, an epiglottic ridge, and a ridged, flattened stem to help insertion and reduce the risk of axial rotation . I-Gel has also been used in difficult airway management and as a conduit for fiber-optic bronchoscopic (FOB) tracheal intubation .
The aim of the current study was to compare between three SADs (Air-Q, ILMA, and I-Gel) as conduit for fiber-optic tracheal intubation in regard to the success rate, easiness, duration of insertion of SAD, duration of insertion of endotracheal tube, safety, and complications.
The primary outcome was the success rate of first attempt of FOB ETT through SAD.
Secondary outcomes include:
- Number of attempts and ease of insertion of the SAD.
- Duration of insertion of the SAD.
- Fiber-optic grading of the laryngeal view.
- The number of attempts performed to insert the ETT through the study device.
- Duration of insertion of ETT.
- Changes in hemodynamic and gas exchange parameters.
- Incidence of passage complications.
| Patients and methods|| |
After receiving the Institutional Research Board approval and informed written consent, this prospective, randomized study (using computer-generated randomization table) was conducted on 81 adult patients (21–65 years), American Society of Anesthesiologists I or II, of both sexes, who were planned to undergo elective operations under general anesthesia with the need to insert ETT. The study was conducted at Zagazig University Hospitals during the period from September 2016 to September 2017. Patients with only Mallampati scores  I and II were included in the study and with a BMI of less than 35 kg/m2. Exclusion criteria included: anticipated difficult airway (score of ≥5 according to El-Ganzouri et al.  airway score) ([Table 1]), history of obstructive sleep apnea, respiratory or pharyngeal pathology, coagulation disorders, full stomach or potentially full stomach (e.g. trauma or pregnancy), esophageal reflux (e.g. hiatus hernia), or surgeries of an expected duration of more than 2 h.
On arrival to the operation room, monitoring was established including pulse oximeter, electrocardiogram, noninvasive blood pressure measurement, and temperature measurement. Intravenous cannula 20 G was inserted. Patients were preoxygenated using a transparent face mask for 3 min and then intravenous induction drugs were given (0.01 mg/kg atropine sulphate, 1 mg/kg lidocaine, fentanyl 1 μg/kg, and propofol 2 mg/kg). After confirming adequate face mask ventilation, intravenous rocuronium 0.5–1.0 mg/kg was given. Ventilation via a face mask with 2% isoflurane was maintained until neuromuscular monitoring using a peripheral nerve stimulator revealed absent response to a train-of-four stimulus and then insertion of the SAD was done followed by fiber-optic ETT application.
The patients were randomly allocated into one of the three groups each containing 27 patients, the Air-Q ILA group (group Q), ILMA (Fastrach) group (group L), or I-Gel group (group G).
- Group Q (27 patients): insertion of the proper size of the Air-Q ILA size 3.5 for female and size 4.5 for male patients was done. Jaw thrust was performed or wooden tongue depressor was used to assist the introduction of the Air-Q ILA. Then the cuff was inflated by 5–10 cm3 as instructed by the manufacturer.
- Group L (27 patients): insertion of ILMA (Fastrach) size 3 for female and size 4 for male patients was done. Then the cuff was inflated by 5–10 cm3 as instructed by the manufacturer.
- Group G (27 patients): insertion of I-Gel size 3 for female and size 4 for male patients was done in the extended neck position.
Figure 1 illustrates the devices that were used in this study.
|Figure 1 The supraglottic airway devices used in the current study: Air-Q ILA, ILMA, and I-Gel. ILA, intubating laryngeal airway; ILMA, intubating laryngeal mask airway.|
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For all patients in the three groups the following was done:
- Confirming proper placement of SADs by the presence of chest elevation using 20 cmH2O positive pressure insufflation, and by the absence of an audible air leak. When connected to a capnograph, a normal square-form tracing is detected.
- The anatomical alignment of the device to the larynx was viewed using a fiber-optic endoscope (Endoskope, iIntubation fiberscope 5.2 mm OD, 65 cm; KarlStorz) to assess the airway’s endoscopic grade as guided by the Brimacombe scale . The images were graded according to a score of 1–5 as follows:
- Grade 4: only the vocal cords are seen.
- Grade 3: vocal cords and posterior surface of the epiglottis are seen.
- Grade 2: vocal cords and anterior surface of the epiglottis are seen.
- Grade 1: epiglottis is downfolded covering more than 50% of the vocal cords.
- Grade 0: epiglottis is downfolded and vocal cords cannot be seen.
- Insertion of the ETT: after visualizing the carina with the FOB, conventional oral ETT size 7 mm ID was introduced into the trachea through the SAD.
- Successful tracheal intubation was confirmed by auscultation of bilateral breath sounds as well as end-tidal carbon dioxide detection by capnography.
- The SADs were removed after extubation of ETT.
Measurements and collected data
In addition to patients’ data, an independent observer who is unaware of the protocol of the study measured the following:
- Ease of insertion of the SAD (Air-Q, ILMA, or I-Gel) as graded on a scale of 1–3 (1=easy, 2=moderate, 3=difficult) based on achieving an effective airway with normal chest movement, auscultation of breath sounds, and a square wave capnograph trace. Easy insertion when effective airway was achieved from the first attempt. Moderate means effective airway was achieved from the second or third attempt. Difficult to insert when failure to achieve an effective airway after three attempts occurs.
- Number of attempts needed for proper insertion of the SAD (Air-Q, ILMA, or I-Gel).
- Time needed for insertion of the SAD (Air-Q, ILMA, or I-Gel).
- Fiber-optic grading of the laryngeal view using the Brimacombe scale .
- The number of attempts performed to insert the ETT through the study device and the success rate of the first attempt was calculated.
- Duration of insertion of ETT defined as the time from loss of CO2 trace on the capnograph, due to disconnection of the circuit for tracheal intubation, to the time of reappearance of the CO2 trace after ETT with no audible leak during positive pressure ventilation.
- Heart rate, mean arterial blood pressure, and oxygen saturation were recorded 1 min before induction. The previous parameters in addition and end-tidal carbon dioxide were recoded 1 min following the insertion of the SAD, and 1 min following the introduction of the ETT.
- When removed, the SAD was inspected for blood stain on the device and was recorded if found. The patients were asked if the sore throat sensation was felt in the first postoperative hour and was also recorded.
The criteria to abort the procedure included:
The procedure was aborted if ventilation was not adequate despite three attempts for placing the SAD. The patient was then intubated via direct laryngoscopy and the case was recorded as failed trial of SAD insertion. The procedure was also aborted if trauma to the passage occurred including bleeding or swelling of the lips, tongue, teeth complications, or trauma to the pharynx or larynx, or if oxygen saturation decreased by more than 5% (as compared with the baseline saturation value of the patient while preoxygenating with 100% oxygen was performed).
Sample size and statistical analysis
The G*POWER program, version 22.214.171.124 (Heinrich Heine; Universitat Dusseldorf; Germany) was used to calculate the number of patients. To calculate the sample size, the success rate of first attempt of FOB ETT through SAD. Twenty-seven patients were needed in each group to achieve an alpha error level of 0.05, with 80% power and 95% confidence limit. Allowing a 5% dropout rate, the total sample size needed was 81 patients equally allocated into 27 patients in each of the three groups to detect a clinically significant difference of more than 20%.
Data were analyzed using the Statistical Package for the Social Sciences) for Windows, version 24 (SPSS, Chicago, Illinois, USA). Qualitative data were represented as frequencies and relative percentage. χ2 and Fisher’s exact tests were used to analyze categorical variables. Quantitative data were expressed as means±SD and then analyzed using one-way analysis of variance. For all the tests in the study, a P value less than 0.05 was considered significant and a P value less than 0.001 was considered highly significant.
| Results|| |
In regard to patients’ data and clinical characteristics, there were no statistically significant differences (P>0.05), between the three groups as shown in [Table 2].
|Table 2 Patients’ data and clinical characteristics in the three groups of the study|
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Regarding the ease of insertion of the supraglottic device and the number of attempts of insertion, there were no statistically significant differences between the Air-Q, ILMA, or I-Gel (P>0.05). The study device was successfully inserted from the first attempt in 25 (92.6%) patients of group Q (Air-Q) and in 23 (85.2%) patients of group L (ILMA) and in 24 (88.9%) patients of group G (I-Gel). Second attempt was required in two (7.4%) patients in group Q and in four (14.8%) patients in group L, and three (11.1%) patients of group G as shown in [Table 3].
|Table 3 Ease of insertion, number of attempts, and duration of insertion of the supraglottic devices in the three groups of the study|
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The duration of insertion of the Air-Q ILA was (13±3 s), while the duration of insertion of ILMA was 19±4 s and the duration of insertion of I-Gel was 18±3 s, indicating highly statistically significant difference (P<0.001) with the duration of insertion of the Air-Q ILA being the shortest as shown in [Table 3] and [Figure 2].
|Figure 2 Duration of insertion of the SADs (sec.). **Indicates highly statistically significant difference (P<0.001) in the duration of insertion of the Air-Q ILA compared to either ILMA or I-Gel. Data were represented as numbers.|
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The fiber-optic grading of the laryngeal view ([Figure 3]) through the SADs showed that there was a significant statistical difference (P<0.05) in favor of group Q compared with groups L and G as shown in [Table 4]. In group Q, 22 (81.5%) of the patients were of grade 4, while grade 3 was seen in four (14.8%) patients; grade 2 was seen in one (3.7%) patient only; and none of the patients was of grade 1. In group L, 13 (48.2%) of the patients were of grade 4; three (11.1%) were of grade 3; 10 (37%) were of grade 2; and only one (3.7%) was of grade 1. In group G, 14 (51.9%) of the patients were of grade 4; 11 (40.7%) were of grade 3; one (3.7%) patient was of grade 2; and also one (3.7%) patient was of grade 1. In this study no patient was seen as grade 0 in all groups.
|Figure 3 Grades of laryngeal view as visualized in the current study: grade 4: vocal cords are totally seen; the epiglottis is not seen at all. Grade 3: vocal cords and the posterior surface of the epiglottis are seen. Grade 2: vocal cords and the anterior tip of the epiglottis is seen. Grade 1: the epiglottis is covering more than 50% of the vocal cords (grade 0: where the epiglottis is completely obstructing the view was not seen in the current study).|
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|Table 4 Fiber-optic grading of laryngeal view through the supraglottic device in the three groups of the study|
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Thereby, fiber-optic laryngeal view grade 4 through the SADs was statistically significantly higher with Air-Q-LMA, grade 3 was statistically significantly higher with I-Gel, while grade 2 was statistically significantly higher with ILMA, indicating the best view with Air-Q-LMA and the worst view with ILMA.
Regarding the number of attempts to insert the ETT through the study device, it was noted that there were no statistically significant differences between the three groups (P>0.05) as follows ([Table 5]):
- In group Q, the ETT was successfully inserted from the first attempt in 26 (96.3%) patients and from the second attempt in only one (3.7%) patient.
- On the other hand, in group L, successful insertion of the ETT was achieved, at the first attempt in 24 (88.9%) patients and at the second attempt in three (11.1%) patients.
- In group G: successful insertion of the ETT was achieved, at the first attempt in 25 (92.6%) patients and at the second attempt in two (7.4%) patients.
|Table 5 Number of attempts and duration of insertion of endotracheal intubation in the three groups of the study|
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Regarding the duration of insertion of the ETT via FOB through the supraglottic devices it was shortest in group Q (35±5 s) when compared with group L (45±7 s) and group G (42±6 s) (P<0.001) which represents a highly statistically significant difference ([Table 5] and [Figure 4]).
|Figure 4 Duration of insertion of ETT (s). **Indicates highly statistically significant difference (P<0.001) in the favor of Group Q as compared to Group L and Group G. Data were represented as numbers.|
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There was no significant statistical difference between the three groups regarding baseline heart rate, mean arterial blood pressure, oxygen saturation. Also, there was no statistically significant difference in hemodynamic and gas exchange parameters between the groups after insertion of the study device or after insertion of ETT.
Regarding the incidence of passage complications encountered during the procedure, blood stain on the SAD was present just after removal from patients’ airway in 10 (37%) cases on the Air-Q ILA, in six (22.2%) cases on ILMA, and only in five (18.5%) cases on I-Gel. Comparison between the three groups showed no statistically significant difference (P>0.05). Sore throat in the first postoperative hour after extubation showed no statistically significant difference between the three groups; on the Air-Q ILA sore throat occurred in eight (29.6%) cases, on ILMA in 10 (37%) cases, and on I-GEL in eight (29.6%) cases (P>0.05) ([Table 6]).
|Table 6 Incidence of blood stain on the supraglottic airway device just after removal and sore throat in the first postoperative hour after extubation in study groups|
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| Discussion|| |
The results obtained in the current study showed shorter times for supraglottic device insertion, shorter time for ETT, and better visualization of the glottis with Air-Q ILA than I-Gel and ILMA while total success rates were similar when used as a conduit for fiber-optic ETT.
The 100% success rate of insertion of supraglottic devices as well as the adequate ventilation through them in the current study were similar to various previously conducted studies ,,,.
In the present study, as regards comparison of the ease of insertion and number of attempts of inserting the SADs, the Air-Q ILA was superior for the I-Gel and ILMA in that order. However, these results were nonsignificant when compared statistically. This was in accordance with the results obtained in the study by Neoh and Choy  who compared Air-Q ILA with ILMA. Moreover, Kleine-Brueggeney et al.  in their study compared I-Gel with ILMA and stated that I-Gel was easier to use than ILMA and explained that by the fact that the I-Gel is more flexible, soft, nonmetallic with better fitting to anatomical curvature than ILMA.
The present study results are in accordance with the results obtained by El-Ganzouri et al.  who supported the use of Air-Q as a conduit for fiber-optic ETT in adult, paralyzed patients. In their study, they compared between two sizes of the Air-Q (3.5 vs. 4.5) guided by the body weight of the patient. They found 100% success rate with the first attempt using size 3.5 and 93.3% with size 4.5. Also, our results are in accordance with the results of the study by Joffe et al.  as they reported a successful insertion time of 22±14 s and a successful insertion rate of 100% of the Air-Q in 70 adult patients. Moreover, the time for insertion of the LMA Fastrach was significantly longer than that of the Air-Q when used for blind tracheal intubation in a study by Karim and Swanson’s .
Regarding the fiber-optic grading of the laryngeal view, results of the current study concluded that Air-Q provided the best fiber-optic laryngeal view and ILMA provided the worst among the three compared devices. A study by Moore et al.  showed better visualization of the glottis with the I-Gel being more than ILMA which is in accordance with the results of the current study. This performance of ILMA might be related to the presence of an epiglottic bar in ILMA which may cause poorer FOB view through ILMA . In the Samir Enas and Sakr Sameh study , Air-Q recorded a full laryngeal view of the vocal cords by FOB in 60% of patients and a partial view of the vocal cords was reported in 36.7% of patients. On the other hand, view of the epiglottis only was reported in one (3.3%) patient of that group. No patients had a grade 1 or 0 view and these results agreed with the results of the present study.
Although the number of attempts of insertion of ETT in the present study showed no statistically significant difference between the three studied groups, the duration of insertion of ETT was significantly shorter in the Air-Q ILA group. These results are in accordance with the results of a study by Samir Enas and Sakr Sameh  who concluded that Air-Q when used as a conduit for FOB helps reduce the time for insertion of the ETT compared with FOB ETT in adult patients with limited cervical spine mobility. A few studies have focused on tracheal intubation through the I-Gel and compared it with ILMA. The study by Moore et al.  showed significantly shorter intubation times with the I-Gel compared with ILMA. They related their results to the design of ILMA having a narrow lumen making the subsequent placement of endotracheal tube technically difficult. However, both devices showed a high success rate for tracheal intubation with similar intubation times in the study by Kleine-Brueggeney et al.  who compared the two devices when used during FOB-guided intubation in anesthetized patients with a difficult airway. The results of the current study support the results of the study by Kleine-Brueggeney et al.  as there were no significant difference between the ETT intubation time through I-Gel and ILMA.
Previous studies ,,, have found that SADs cause minimal oropharyngolaryngeal stimulation with subsequent stable hemodynamics. These findings are consistent with the results of the current study since the changes in hemodynamics were insignificant in the three groups of the study. On the other hand, Zhang et al.  found that intubation using ILMA causes the same pressor response as direct laryngoscopy. They explained their results by that during tracheal intubation through ILMA, the epiglottic bar of the ILMA elevates the epiglottis resulting in stimulation of the epiglottis and the surrounding structures.
One of the drawbacks of using SADs as a conduit for FOB ETT intubation is the unintended extubation during removal of the SAD . The recent generations of SADs allowed for longer durations of their continuous use. First-generation SADs were recommended for not more than 2 h, whereas I-Gel was stated to be safe for up to 4 h of continuous application according to the manufacturer . Moreover, other studies regarding prolonged use of SADs did not find any adverse events for over 7 , 9 , and 24 h . Thereby, in the current study we chose to leave the SADs in place until after extubation of ETT. In spite of being statistically insignificant, blood stains on the Air-Q ILA in this study were more than those on the ILMA and I-Gel. This might be explained by the large size of Air-Q (3.5–4.5) compared with the ILMA (3–4) and I-Gel (3–4). This was in agreement with the results of many studies ,,.
Regarding sore throat, in current study, there was no statistically significant difference between the study groups which were in accordance with the results obtained by Neoh and Choy’s  and Karim and Swanson’s . On the other hand, Bashandy and Boules  found that more patients in the Air-Q group reported sore throat compared with ILMA (46 vs. 38%). These variations in results between the different studies might be attributed to the multiple factors that may lead to the occurrence of postoperative sore throat including depth of anesthesia, the method of insertion, the cuff volume with inflatable devices, and the number of insertion attempts  and not always related to the device itself.
Limitation and recommendation
The duration of stay of the SADs was not recorded nor compared in the current study. Recommendation is made toward accurate assessment of the duration of stay of each SAD and relating it to passage complications in further studies.
| Conclusion|| |
The three SADs (Air-Q, ILMA, and I-Gel) were proved to be useful conduits for fiber-optic ETT with similar success rates. The Air-Q ILA provided better laryngeal view and shorter time for insertion of both the device and the ETT than the Fastrach ILMA and I-Gel.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4]
[Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6]