Blind Tracheal Intubation through the Air-Q Intubating Laryngeal Airway in Pediatric Patients: Reevaluation - A Randomized Controlled Trial.

CONTEXT: Some pediatric supraglottic airway devices have not been evaluated in a large perspective for blind intubation although they are validated as a conduit for fiberoptic-guided intubation.
OBJECTIVE: The objective of this study was to compare the success rate of blind technique with correction maneuvers versus fiberoptic-guided intubation through the air-Q laryngeal airway in pediatric patients. PATIENTS AND METHODS: One hundred and twenty-six pediatric patients undergoing elective surgery under general anesthesia were randomized into two equal groups. The air-Q was placed in all patients as a conduit for tracheal intubation. Group B patients underwent blind intubation with correction maneuvers. Group F patients underwent fiberoptic-guided intubation.
RESULTS: There was no significant difference between the groups regarding the success rate of intubation or postextubation complications. Group F patients showed a significantly longer time to intubation and total time of the trial. Furthermore, Group F patients showed a significantly higher level of pre- and postintubation heart rate compared to Group B patients.
CONCLUSION: Blind tracheal intubation in pediatric patients through the air-Q with correction maneuvers could be a good alternative for fiberoptic-guided intubation with stable hemodynamics and shorter time till intubation.

INTRODUCTION

According to airway management guidelines in both adult and children; the supra-glottic airway devices (SGAs) represent the plan ‘B’ in case of failed mask ventilation and intubation.[1]

Regarding tracheal intubation in pediatric patients, the air-Q intubating laryngeal airway (ILA) is considered as an ideal SGA device for this purpose. The advantages of air-Q ILA are as follows: it can accommodate the passage of endotracheal tube (ETT) with its pilot balloon, its hyper-curved, wide and and short bowl allows both blind and fiberoptic bronchoscope (FOB)-guided intubation.[23]

The modern tip design prevents mask folding during insertion, and an accessory hole prevents downfolding of the epiglottis and improves airflow. The keyhole-shaped ventilating orifice of the air-Q (ILA) allows the direction of ETT in the midline toward the laryngeal inlet, and the mask ridges are enabled for better anterior mask seal.[456]

In spite of the previous advantages of air-Q, it has some complications. Time-consuming, lack of experience, and the presence of secretions may hinder its utilization. The available literature documented a low success rate for the blind intubation through the air-Q.[17]

This study aimed to compare the success rate of blind intubation with correction maneuvers versus fiberoptic-guided intubation through the air-Q laryngeal airway in pediatric patients. We hypothesized that the use of correction maneuvers such as jaw thrust, external laryngeal manipulation, and clockwise rotation of the ETT may increase the success rate of blind intubation through the air-Q.

The first-trial success rate was the primary outcome of this trial, whereas the total success rate, number of attempts, time to ventilation (from beginning of air-Q insertion till normal capnography waveform), time to intubation (from beginning of manipulation of the ETT till normal capnography waveform), hemodynamics (heart rate [HR] and mean arterial pressure [MAP]; pre- and post-intubation), and complications of airway manipulation (blood staining of the device, postintubation croup, hoarseness; Graded 1–4 for non, mild, moderate, and severe, respectively) were secondary outcomes.

PATIENTS AND METHODS

Patients

Approval of the ethical committee of our medical institution (R/17.11.129) and registration in the ClinicalTrials.gov (NCT 03778762) were fulfilled. This randomized controlled study was conducted on 126 pediatric patients scheduled for elective surgery under general anesthesia over the period between December 2017 and September 2018. Written consent was obtained from the parents of each child enrolled in the study. The participants were between 2 and 7 years old, they were American Society of Anesthesiologists physical Status I–II, and their weights were between 11.5 and 24.5 kg. Exclusion criteria included obesity (BMI ≥95%) or history of gastroesophageal reflux disease or hyperactive airway patients and congenital disorders associated with difficult airway or any known difficult airway.

Randomization

Patients were randomly allocated into two groups of 63 children each according to the order of computer-generated randomization program. Each patient was assigned to F or B according to his/her group followed by a number from 1 to 126 according to his/her order. All patients were intubated through the air-Q (disposable, Cookgas LLC, St. Louis, MO, USA; size 1.5 for 7–17 kg, size 2 for 17–30 kg). Patients of Group B were intubated blindly through the air-Q, whereas patients of Group F were intubated using FOB (Pentax, ultra-slim, size 3.5 mm OD) through the air-Q.

Study protocol

Demographic data (age, gender, and weight) were recorded. Patients’ HR, NIBP, ETCO2, and SpO2 were monitored pre- and postintubation immediately. The air-Q cuff was inflated to prevent perilaryngeal leak using 5–10 mL air according to the manufacturer's recommendations.

Anesthesia was induced by sevoflurane (8%) in 60% air and 40% oxygen. Intravenous access was obtained after induction. The back of the cuff and the cavity ridges were lubricated by lidocaine 2% gel. With the cuff being partially inflated, the air-Q was inserted laterally at the angle of the opened mouth along the hard and soft palates; posterior pharyngeal wall till resistance of the upper esophagus was encountered by the tip of the cuff of the air-Q. Then, the device was left to be repositioned by inflating the cuff where its aperture closely faces the larynx as evidenced by adequate tidal volume (>5 mL/kg) and normal capnography waveform in a spontaneously breathing child. At this moment, time to ventilation was measured; then, patients were maintained on 3%–4% sevoflurane, rocuronium 0.6 mg/kg was administered, and the leak pressure was measured (by giving 3–5 L/min fresh gas flow), whereas the adjustable pressure-limiting valve is closed till equilibrium where manometer pressure equals leak pressure).[3]

According to the group of the patient, a well-lubricated (using lidocaine 2% gel), appropriately sized ETT either blind (Group B) or FOB guided (Group F) was used. In Group B, jaw thrust and external laryngeal manipulation by an assistant anesthetist were afforded to each patient. The lubricated ETT was loaded with clockwise rotation of the tube, and tracheal intubation was confirmed by capnography waveform; then, the combined jaw thrust and external laryngeal manipulation were released. Then, after the connector of the ETT was removed, an exchange removal stylet was used for the removal of the air-Q after deflation of the cuff. The ETT was reconnected, and the capnography waveform was used for the confirmation.[1] At this moment, the time of intubation was measured.

In Group F, a 3.5-mm outer diameter FOB (ultra-slim, Pentax) loaded with the appropriately sized ETT was introduced through the air-Q till reaching the glottis (1st landmark), tracheal rings (2nd landmark), and carina (3rd landmark). The ETT (its connector was removed already before loading over FOB) was introduced through the air-Q. The cuff of the air-Q was deflated, and the device was removed over the FOB. While taking FOB out from the trachea; confirm ETT correct placement by observing the carina, tracheal rings and the tip of ETT. After FOB was removed, the ETT was reconnected and confirmed by capnography waveform. At this moment, intubation time was measured.[3]

For each patient of both the groups, two trials of intubation either blind or FOB guided were allowed till normal capnography waveform appears. The failure of the second-attempt blind intubation through air-Q shifts the trial to FOB-guided one, whereas the failure of the second-attempt FOB-guided intubation shifts it to conventional laryngoscopic one. Failed attempt was defined as absent chest rise, absent normal capnography waveform, and inadequate tidal volume (<5 mL/kg) or spontaneous dislodgement of the device. For reinsertion or reintubation, times of both trials were summated. Senior anesthesiologists from the team of pediatric anesthesia performed all the airway interventions.

Sample size

A prior G-power analysis was done to estimate the sample size. The primary outcome of this study was the first-trial success rate. Using Fisher's exact test and assuming α (Type I error) = 0.05 and β (Type II error) = 0.2 (power = 80%), 58 patients per group would be sufficient to detect the difference of 10% in success rate among the groups. A drop out 10% of cases was expected; therefore 63 patients were required in each group to detect the difference.

Statistical analysis

Statistical analysis was performed using the Statistical Package for the Social Sciences (IBM Crop. Released 2013. IBM Statistics for Windows, version 22. Armonk, NY, USA: IBM Crop). For quantitative data, normality was first evaluated with the Kolmogorov–Smirnov test and then analyzed with the Student's t-test. The data that do not have a normal distribution, as well as ordinal data, were analyzed with the Mann–Whitney U-test. For binomial data, Fisher's exact test was used. All P values presented here were two-sided, and P < 0.05 was considered statistically significant.

RESULTS

A total of 126 participants were enrolled in this study [Figure 1] with no significant difference regarding their demographic data [Table 1]. Group F patients showed a statistically significant higher level of HR compared to Group B both pre- and postintubation [Table 2]. Postextubation complications (croup and hoarseness) showed no significant difference between the groups [Table 3]. Group F patients showed a highly significant longer time to intubate and total time of the trial compared to Group (B) [Figure 2], while Figure 3 does not carry any significant difference between both groups regarding success rate of intubation either in the first or the second trial or in the total success rate. In both the groups, the range of size of air-Q was 1.5–2 and of the ETT was from 4 to 5 mm internal diameter.

Figure 1

Consort flow diagram

Table 1

Demographic data of the studied groups

	Group B (n=63)	Group F (n=63)	P
Sex (female/male)	32/31	30/33	0.7
Age (years)	4.4±2.17	4.5±2.7	0.7
Weight (kg)	15.86±4.17	17.2±7.3	0.5

Data are presented as mean±SD or n. SD=Standard deviation

Table 2

Pre- and postintubation hemodynamic variables of the studied groups

	Group B (n=63)	Group F (n=63)	P
HR (beat/min)
Preintubation	128.66±5.45	137.5±6.13	0.0001**
Postintubation	129.86±5.91	138.8±5.77	0.0001**
MBP (mmHg)
Preintubation	64.73±6.19	66.46±8.72	0.2
Postintubation	66.73±6.60	68.53±8.1	0.2
SpO2 (%)
Preintubation	98.00±0.75	98.33±0.61	0.19
Postintubation	91.20±2.17	92.00±2.17	0.3

Data are presented as mean±SD. *P≤0.05 was considered statistically significant, SD=Standard deviation, HR=Heart rate, **P≤0.01 was considered as highly significant

Table 3

Postextubation complications (croup/hoarseness)

	Group B (n=63), n (%)	Group F (n=63), n (%)	P
Post extubation croup	9 (14)	14 (22)	0.2
Post extubation hoarseness	9 (14)	17 (27)	0.07

Figure 2

Time to ventilate, time to intubate, and total time. Group B: Intubated through air-Q blindly. Group F: Intubated through air-Q using FOB. **P ≤ 0.01

Figure 3

Success rates of intubation. Group B: Intubated through air-Q blindly. Group F: Intubated through air-Q using FOB

DISCUSSION

This study aimed to compare the success rate of blind intubation with correction maneuvers versus fiberoptic-guided intubation through the air-Q laryngeal airway in pediatric patients. In accordance with our initial hypothesis, the study documented a comparable success rate of both the techniques.

Supra-glottic airway devices (SGAs) represent an essential part of routine and emergency airway management in pediatric patients. Over 30 years ago, many of new SGAs have introduced into clinical practice.[8]

The air-Q is a laryngeal mask characterized by its oval shape. It has a short, wide, and hyper-curved airway tube. Keyhole-shaped ventilating orifice prevents epiglottis downfolding. However, downfolding can still occur in the younger age group.[910]

A retrospective assessment of predicted and unpredicted difficult airways revealed that the air-Q was a good choice as a conduit for intubation in both groups.[11] A case series reported that the air-Q even the small-sized one allowed adequate ventilation in children with limited mouth opening and was still an effective conduit for fiberoptic-guided tracheal intubation with an appropriately sized cuffed ETT.[12]

Many studies have shown a preference for air-Q over classic laryngeal masks and the Ambu Aura-I as a conduit for fiberoptic-guided tracheal intubation in pediatric patients.[10111213] This can be attributed to its ability to maintain the thin pediatric FOB in the midline position[3] and to facilitate tracheal intubation with larger cuffed ETT even with a smaller size of air-Q.[13] The air-Q has also been used during rapid-sequence fiberoptic intubations to relieve upper airway obstruction[13] and to allow oxygenation during fiberoptic tracheal intubations in children with anticipated difficult airways.[111213]

Some pediatric SGAs are not evaluated for blind intubation although they are validated for fiberoptic-guided intubation.[910] Thus, manufacturers do not recommend the air-Q and Ambu Aura-i for blind intubation to avoid epiglottic downfolding and potential injury to the epiglottis or the glottis.[1415] In spite of this, blind intubation through pediatric SGA continues to be practiced in case of a failed trial due to airway bleeding or if the pediatric FOB is unavailable.[16]

In this context, Jose et al. examined blind intubation through the air-Q versus intubating laryngeal mask airway. They reported a better vision of glottis with air-Q in the second attempt and a similar percentage of successful intubation between both devices. The authors recommended further studies to assess the efficacy of correction maneuvers to facilitate the intubation.[17]

Brueggeney et al. carried out a randomized trial on blind intubation in pediatric patients through the air-Q and Ambu Aura-i on the basis of fiberoptic view data (visualized blind intubation). They reported that blind intubation was possible in only 15% of cases with the air-Q. They attributed this low success rate to that the optimal fiberoptic view which is essential for successful blind intubation, was possible only in 21% of cases. The authors can’t exclude alteration of the pat of ETT caused by the usage of fiberoptic. Furthermore, in true blind intubation, a little force may be helpful in some cases but with a risk of airway trauma or esophageal intubation.[1] Brueggeney et al. showed that correction maneuvers such as 180° rotation of ETT, head extension, and flexion may increase the success rate, and this expectation is confirmed in our study.

In a study carried out by El-Ganzouri et al., a success rate of 70% was reported for blind tracheal intubation through the air-Q compared to 97.5% for the freehanded fiberoptic-guided intubation.[6] However, in El-Ganzouri's study, the group of blind intubation showed a statistically significant higher median airway score compared with FOB-guided intubation. This could be the cause of the higher failure rate, besides that more trials of blind intubation were more traumatic compared to FOB-guided intubation. Furthermore, the authors did not apply any correction maneuvers during blind intubation apart from cricoid pressure. Regarding the age group, El-Ganzouri's study was carried on adults, so their results may be confined to this age group. Finally, the authors mentioned that their study was the first one in Egypt dealt with air-Q and attributed these results to the nonfamiliarity with the device.[6]

In the current study, the correction maneuvers, including jaw thrust, external laryngeal manipulation, and tube rotation during blind intubation through the air-Q offer success rates comparable to that of fiberoptic-guided intubation. Participants of the current study are of different age groups (pediatric patients), and any case of suspected difficult intubation was excluded from the study.

The time till tracheal intubation and the total time from insertion of the air-Q till successful intubation were significantly longer in fiberoptic-guided intubation group. On the other side, many of the correction maneuvers needed with the blind technique should be taken into consideration, especially with limited staff number. However, we noticed that external laryngeal manipulation was the most effective maneuver, and more studies are needed to validate this finding.

Limitation of the study

The study excluded participants with difficult airways, so the results may not be applicable to those patients. Furthermore, study participants were pediatric patients, so more studies are needed to test these results on other age groups.

CONCLUSION

In pediatric patients, blind tracheal intubation through the air-Q with correction maneuvers has a comparable success rate to that of fiberoptic-guided intubation through the air-Q with stable hemodynamics and shorter time of intubation.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.