|Year : 2019 | Volume
| Issue : 1 | Page : 21-25
Comparative evaluation of air-Q and classic laryngeal mask airway for surgeries under anesthesia: A randomized open-label trial
Susheela Taxak1, Pooja Jaju Bihani2, Rishabh Jaju2, Kirti Kamal1, Mangal Ahlawat1, Priyanka Sethi2, Raksha Vyas2
1 Department of Anesthesiology and Critical Care, Pt. B.D.S. PGIMS, Rohtak, Haryana, India
2 Department of Anesthesiology and Critical Care, All India Institute of Medical Sciences, Jodhpur, Rajasthan, India
|Date of Submission||11-Jan-2018|
|Date of Acceptance||28-Jan-2019|
|Date of Web Publication||6-May-2019|
Dr. Rishabh Jaju
Department of Anesthesiology and Critical Care, All India Institute of Medical Sciences, Jodhpur, Rajasthan
Source of Support: None, Conflict of Interest: None
Objective: Classic laryngeal mask airway (cLMA) is a prototype supraglottic airway device, and Air-Q is a newly introduced device for use as a primary airway and as an aid for intubation. Due to paucity of literature comparing Air-Q with cLMA, this prospective, randomized, single-blinded study was performed, to evaluate their clinical performance as a primary airway conduit.
Methods: Sixty patients of either sex with the American society of anesthesiology Grade I or II, weighing between 50 and 70 kg, were randomly allocated to either the cLMA (n = 30) or Air-Q (n = 30) group. After induction of anesthesia, the assigned airway device was introduced. The ease of insertion, vital parameters, oropharyngeal seal pressure (OSP), airway morbidity, and fiberoptic grades of laryngeal view was recorded.
Results: There was no significant difference in ease of insertion, the time taken for successful device placement, number of attempts, or postoperative morbidities. Air-Q was found better with respect to hemodynamic stability during placement of the device. There was a significant difference in the OSP between the Air-Q (22.12 ± 1.740 cm H2O) and cLMA (16.28 ± 2.052 cm H2O), P < 0.001. Fiberoptic laryngeal view through Air-Q was also superior (P < 0.001).
Conclusion: Air-Q was found to be superior to cLMA for controlled ventilation in view of better OSP and a superior fiberoptic laryngeal view.
Keywords: Air-Q, classic laryngeal mask airway, fiberoptic laryngeal view, oropharyngeal seal pressure
|How to cite this article:|
Taxak S, Bihani PJ, Jaju R, Kamal K, Ahlawat M, Sethi P, Vyas R. Comparative evaluation of air-Q and classic laryngeal mask airway for surgeries under anesthesia: A randomized open-label trial. Indian Anaesth Forum 2019;20:21-5
|How to cite this URL:|
Taxak S, Bihani PJ, Jaju R, Kamal K, Ahlawat M, Sethi P, Vyas R. Comparative evaluation of air-Q and classic laryngeal mask airway for surgeries under anesthesia: A randomized open-label trial. Indian Anaesth Forum [serial online] 2019 [cited 2019 Oct 18];20:21-5. Available from: http://www.theiaforum.org/text.asp?2019/20/1/21/257677
| Introduction|| |
The use of supraglottic devices for airway management has gained wide popularity for surgeries requiring general anesthesia. Their advantages include avoidance of laryngoscopy, increased ease of placement, improved hemodynamic stability, less coughing, and less sore throat compared to endotracheal intubation. However, the main concern regarding their use is the inability to provide a full proof perilaryngeal seal and the subsequent risk of aspiration intraoperatively.
Classic laryngeal mask airway (cLMA) is a well-established device for airway management in children as well as adults with a long history of safety and reliability. The Air-Q (Cookgas LLC, Mercury Medicals, Clearwater, FL, USA) is a new supraglottic airway device for use as a primary airway and as an aid for endotracheal intubation. Its characteristic features include a curved airway tube, raised mask heel, keyhole-shaped ventilating orifice, and easily removable airway adapter. The structure of mask bowl approximates better with oropharyngeal anatomy and leads to better oropharyngeal seal pressure (OSP).,,
Due to paucity of studies on the comparison of Air-Q with cLMA, this prospective, randomized study was conducted to evaluate their clinical performance as a primary airway conduit in adult patients. We hypothesized that Air-Q would have better OSP than cLMA and would provide a better fiberoptic laryngeal view compared with cLMA.
| Methods|| |
After approval from Institute Ethical Committee, this prospective, randomized study was carried out. We enrolled 60 patients of either sex belonging to the American Society of Anesthesiology (ASA) physical status Class I or II and weighing between 50 and 70 kg, scheduled to undergo elective surgery for <1½ h duration under general anesthesia. An informed and written consent was taken. Patients having active upper respiratory tract infection, difficult airway, restricted mouth opening, risk of aspiration, surgery in positions other than supine, history of upper gastrointestinal surgery, and bleeding or clotting abnormalities were excluded from the study. Using computer-generated random number sequence, patients were allocated to one of the two groups. Demographic characteristics, type, and duration of surgery were noted.
Patients were premedicated with tab alprazolam 0.25 mg and tab ranitidine 150 mg at bedtime and 2 h before surgery. In operation theater, routine anesthesia monitors comprising of the electrocardiogram, non-invasive blood pressure (NIBP), pulse oximeter, and temperature were applied. After adequate preoxygenation, general anesthesia was induced with bolus administration of fentanyl (2 μg/kg) and propofol (2 mg/kg) and atracurium (0.5 mg/kg). Anesthesia was maintained with 66% nitrous oxide in oxygen and sevoflurane.
For Air-Q insertion, the cuff was deflated to cause visible dimpling in the posterior portion of the cuff and lubricated at its external surface. After opening mouth of the patient and elevating the tongue, the device was placed with the front portion of the device mask between the base of tongue and palate at a slight forward angle and passed into position within the pharynx by gently applying inward and downward pressure, using the curvature of the Air-Q mask and airway tubing as a guide. If initial resistance to advancement was met, a mandibular lift was performed, while the device was rotated inwardly and forward to its position. The device was advanced until fixed resistance to forward movement was felt, and cuff was inflated to 60 cm H2O pressure (15–17 ml air for size 3.5 size Air-Q). The correct placement was assessed by the presence of square-shaped EtCO2 graph on monitor, chest auscultation, and adequate chest rise.
For cLMA, it was introduced as per the standard recommended technique by brain, involving a completely deflated cLMA, held like a pen, guided into the pharynx with the index finger of the operator at the junction of the tube and the bowl, with the operator at the head of the patient and the cLMA aperture facing caudally. With the head extended and the neck flexed by using the hand under the occiput, the tip of the cuff was pressed upwards against the hard palate till a resistance is felt, and the cuff was inflated with 25–30 ml air to 60 cm H2O pressure.
All devices were inserted by one of the primary investigators; both of them were well experienced with using both devices and insertion techniques. Vital signs (heart rate [HR], SpO2, EtCO2, and NIBP) were recorded at the baseline level, after induction, after placing airway device at intervals of 1 min, 2 min, 5 min, and 10 min.
The insertion time was measured from the moment of picking up the device (T0) to obtaining effective ventilation as confirmed by EtCO2 tracing on the monitor (T1). In the event of complete or partial airway obstruction or a significant leak, the mask was removed, and reinsertion attempted. A maximum of three insertion attempts were allowed before the placement of the device was considered as a failure. In case of failure, alternative airway device was used to secure the airway. The OSP was determined by switching off the ventilator at a fixed gas flow of 3 L/min with the expiratory valve completely closed and recording the airway pressure (maximum allowed 40 cm of water) at which equilibrium was reached.
After the device was in place, leak tested, and secured, a fiberoptic bronchoscope was placed to the end of the airway tube and the relationship of the bowl of the mask to the vocal cords was graded using the view (fiberoptic laryngeal view) at the eyepiece as follows: 1 = full view of the vocal cords, 2 = partial view of the cords including arytenoids, 3 = epiglottis only, and 4 = other (SAD cuff, pharynx, and other).
At the end of surgery, anesthesia was discontinued, and the residual effect of neuromuscular blockade was reversed. The airway device was removed when the patient was awake, responding to verbal commands and the protective reflexes returned. The cuff was left inflated during removal. After removal, the airway device was grossly examined for the presence of bile or blood. In the recovery room, once the patient was fully awake, an observer asked standard oral questionnaire to the patient to determine if sore throat, difficulty in swallowing or speaking was present. Patients were followed up for 24 h to assess the frequency of oropharyngeal complaints.
The primary outcome variable of this study was the comparison of OSP of cLMA and Air-Q. Secondary outcome variables were comparison of subjective ease, insertion time, fiberoptic grade of laryngeal view, hemodynamic changes, and postoperative complications.
Sample size was determined based on our primary outcome variable, i.e., OSP. In a study conducted by Shariffuddin and Wang, the OSP in cLMA group was found to be 15 ± 5.2. Assuming a noninferiority limit of 4, 29 subjects in each group would provide 5% of significance level and 90% power. Statistical testing was conducted with the statistical package for the social science system version SPSS 20.0 (IBM SPSS Statistics for Windows, Version 20.0. Armonk, NY: IBM Corp). The comparison of normally distributed continuous variables between the groups was performed using Student's t-test and Mann–Whitney U test when criteria for normal distribution were not met. Nominal categorical data between the groups were compared using Chi-squared test or Fisher's exact test as appropriate. P < 0.05 was considered statistically significant.
| Results|| |
Sixty patients were enrolled and were randomized in two groups according to the airway device placed (cLMA or Air-Q). None of the patients were excluded because of violation in study protocol or refusal to participate after the consent was signed. The two groups were similar demographically in terms of age, gender, weight, height, ASA physical status, and duration of surgery [Table 1]. Therefore, results obtained after study were purely due to the characteristics attributable to devices rather than any bias associated to the sample selected.
|Table 1: Baseline characteristics of patients undergoing anesthesia with the classic laryngeal mask airway and Air-Q|
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HR and mean arterial pressure (MAP) increased significantly after placing the airway device as compared to baseline in both groups but the rise was more with cLMA group compared with Air-Q group and all parameters returned to baseline values in both groups after 10 min of placement of airway [Figure 1] and [Figure 2].
There was no statistically significant difference with regard to the subjective ease of insertion, time, and number of attempts taken to successfully place the devices. A significant difference was noted with OSP of the two devices (16.28 ± 2.052 and 22.12 ± 1.740 cm H2O for cLMA and Air-Q group, respectively; P < 0.001). The difference noted in the fiberoptic laryngeal view through the two devices was also found to be statistically significant (P < 0.001). The best view (Grade I) was found in 4% and 84% patients in cLMA and Air-Q groups, respectively, whereas Grade II was seen in 64% and 12% cases in two groups, respectively. The downfolding of epiglottis (Grade III) was seen in 32% of cases of cLMA and only 4% cases of Air-Q group. There was no incidence of, laryngospasm, bronchospasm, blood on device, sore throat, or hoarseness of voice postoperatively in both groups [Table 2].
| Discussion|| |
In this study, we observed that although both cLMA and Air-Q are effective and safe devices for use as a primary airway conduit during positive pressure ventilation, Air-Q provides better seal pressure. Air-Q is better than cLMA with respect to hemodynamic stability on the placement of the device. A better fiberoptic laryngeal view is observed through Air-Q as compared to that with cLMA.
The OSP was found to be higher for Air-Q than cLMA in this study. The OSP recorded for cLMA was similar to the mean OSP noted in previous studies.,, Mean OSP reported for cLMA in previous studies is 16–20 cm H2O.,, Reported mean OSP for Air-Q is found to be higher than cLMA in various studies (22–28 cm H2O).,,, Design features unique to Air-Q which might have contributed to an improved OSP are anterior curve of the airway tube, mask ridges, and higher posterior heal height. OSP differences may not have a clinical significance during spontaneous ventilation but may be an important consideration if positive pressure ventilation is being used. Although both cLMA and Air-Q were found to be adequate for controlled ventilation, Air-Q was more effective in providing a leak-free glottis.
Hemodynamic responses between two groups at various time intervals showed statistically significant increase in HR, and MAP as compared to baseline in both groups, but this increase was more in cLMA group. Better hemodynamic stability with Air-Q can be explained by its characteristic wide, short, and hypercurved airway tube which approximates better with upper airway anatomy and provides easy and smooth insertion.
The time taken to establish effective airway, first attempt success, and the ease of insertion were similar for both devices and findings are concordant with previous studies.,,,,
In this study, overall fiberoptic grades of laryngeal view were more favorable (Grade I and II) through the Air-Q when compared with cLMA which is consistent with the findings of previous studies.,, The design of Air-Q, with an area above the ventilating orifice for the epiglottis to rest on when properly positioned, may have contributed to the finding of better grades of laryngeal view. This also explains the successful blind as well as fiberoptic guided intubation through Air-Q in previous studies.,
The limitation of our study was that we compared a single-sized Air-Q with cLMA, both being a first generation supraglottic airway. As cLMA is a prototype airway and no trials were available on the comparison of cLMA with Air-Q, we planned to compare these two devices. Being an open-label trial, observer bias inherent to study design could not be ruled out.
| Conclusion|| |
This study concludes that either of the two devices (Air-Q and cLMA) can be used for airway management during positive pressure ventilation whenever a first-generation supraglottic airway device is indicated during anesthesia. However, Air-Q should be preferred due to a higher OSP and appears to be superior to cLMA as a primary airway. Air-Q appears to be a better device as an intubation aid since it offers a better fiberoptic view of larynx.
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Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2]
[Table 1], [Table 2]