An observational study of the feasibility of Airtraq guided intubations with Ring Adair Elvin tubes in pediatric population with cleft lip and palate.

CONTEXT: The airway management requires refined skills and technical help when associated with cleft lip and palate. Airtraq has improved our airway management skills and has been successfully used for rescue intubation in difficult pediatric airways. AIMS: This study was to evaluate the efficacy of Airtraq as the primary intubation device in patients with cleft lip and palate. The study adheres to the STrengthening the Reporting of OBservational Studies Epidemiology Statement. SUBJECTS AND METHODS: A total of 85 children posted consecutively for lip and palate repair were enrolled. Children were intubated with Ring Adair Elvin (RAE) tube using size 1 and 2 of Airtraq device. The design of Airtraq has an anatomical limitation to hold RAE tubes. The preformed bend of the tube was straightened with a malleable stylet. The intubations were assessed for device manipulations and time taken for glottis visualization and intubation, airway complications such as bleeding, laryngospasm and failed intubations. STATISTICAL ANALYSIS USED: The outcome data were reported as numbers and percentages or range with identified median value, where applicable.
RESULTS: The success rate of Airtraq guided intubations was 98.21%. The cumulative insertion times and intubation times were 31.50 ± 12.57 s and 48.04 ± 35.73 s respectively. Airtraq manipulations were applied in 25.45% subjects.
CONCLUSIONS: The presence of cleft lip or palate did not hamper the insertion of Airtraq. The use of malleable stylet to facilitate the loading of the preformed tube into the guide channel is a simple and efficacious improvisation. Airtraq can be utilized as a primary intubation device in children with orofacial clefts.

INTRODUCTION

Airway related problems account for the majority of anesthetic morbidity in pediatric anesthesia. The presence of congenital orofacial clefts distort the upper airway anatomy and association with wider palatal clefts, bilateral cleft lips, major nasal deformity, micrognathia, and receding mandible further increases the intubation difficulty score. The prevalence of poor laryngoscopic views in a study performed on 800 children with cleft lip and palate was reported as 42.25%. Difficult intubation was noticed in 8.38% of patients and the incidence of failed intubation was 1%. All intubations were attempted with Macintosh laryngoscope.[1]

Airtraq is an optical video laryngoscope (VL) (Airtraq®, Prodol Meditec S.A., Vizcaya, Spain) introduced for managing difficult airways, both in adults and children. The device does not require the alignment of oral, pharyngeal and tracheal axes for establishing the airway. Two pediatric sizes of the device are available (size 1 for 2.5–3.5 mm tube and a size 2 for 4.0–5.5 mm tube). There is a guiding channel for loading and directing the endotracheal tube (ETT). The arcuate design of the channel is conformed to receive a regular tube. Ring Adair Elvin (RAE) tubes have a preformed bend, which does not fit into this channel. The tube needs to be temporarily straightened for ensuring insertion into the device. The objective of our study was to evaluate the feasibility of utilizing Airtraq as primary intubation device with RAE tubes (loaded on malleable stylet) in pediatric patients posted for cleft surgeries.

SUBJECTS AND METHODS

85 children with cleft lip and palate posted for surgery were enrolled for the study. Children with congenital heart disease, active respiratory tract infection and associated syndromes with cleft deformity were excluded [Figure 1]. The Institutional Ethics Committee approval and informed assent was obtained. The study period was of 10 months from March to December 2012. We had decided to include all children American Society of Anesthesiology I-II posted for cleft surgery (lip and palate, primary palate repairs and secondary palatoplasty) in the study protocol, operated during the study period. Cosmetic nose repairs, lip repairs and columellar lengthening procedures were not included.

Figure 1

Unassembled parts of Airtraq assembly

Clear fluids were allowed up to 4 h prior to intubation. They were premedicated with midazolam syrup 0.5 mg/kg ½ h before induction process was started. The operation theatre and airway cart were prepared for a pediatric case. The Airtraq assembly was checked for adequate size, light source and connections to the monitor. The preformed bend of the RAE tube was reshaped using a malleable stylet. The stylet was introduced up to the bend of RAE tube as illustrated in Figure 2. Standard monitoring of electrocardiogram, noninvasive blood pressure and SpO2 was instituted after shifting the child inside theatre. Sevoflurane 5–8% in 100% O2 with pediatric closed circuit was used for obtaining intravenous access and inhalational induction. 0.05 mg/kg glycopyrrolate, 2 µg/kg fentanyl and 0.5 mg/kg atracurium was administered intravenously for intubation. The Airtraq was gently introduced into the oral cavity and advanced to visualize the glottis. The Airtraq was maneuvered to maintain the glottic opening in the center of the view and the RAE tube was advanced towards glottis. The relative position of the tube in relation to the glottis was noted and the Airtraq was adjusted to obtain tube-glottis alignment. Once trachea was intubated, the RAE tube was gently disengaged from the Airtraq. Airtraq was removed while holding the tube at the lower lip of patient. The stylet is withdrawn next and the tube is attached to anesthesia circuit and intubation confirmed with capnography. The RAE tube regained its initial preformed shape after the removal of the stylet. The child was not allowed to desaturate below 95% during intubation and duration of one intubation attempt was restricted to a maximum of 40 s. In either of the situations, Airtraq was removed, and the child was ventilated with 100%O2. Intubation was reattempted after SpO2 returned to ≥98%. A successful intubation was the end point of our study.

Figure 2

Airtraq assembly ready for intubation

The following data was noted – Insertion time (defined as the time taken from insertion of Airtraq in the oral cavity to visualization of glottis), Intubation time (defined as the time interval between visualization of glottis to intubation. This included time taken for Airtraq manipulations and repeated intubation attempts), number of optimization manipulations or adjustments required to align the Airtraq to glottis or tube to glottis, need of application of external laryngeal manipulation and additional intubation aides such as gum elastic bougie (GEB). If the tube advanced repeatedly posterior to the glottis, the stylet was replaced with GEB to direct the tube into the glottis. A cumulative insertion time and intubation time were considered for multiple intubations. Intubation using Airtraq was abandoned, if it required greater than three attempts of intubation or if bleeding or laryngospasm occurred during the attempts of intubation. This was considered as failed intubation. The patient was ventilated with facemask and intubation was then performed using Macintosh laryngoscope. The presence of airway trauma (injury to lips, blood seen in the oral cavity or staining of Airtraq blade) was noted.

Further anesthetic was maintained with 1 MAC isoflurane and atracurium. 0.25% bupivacaine 4–8 ml was infiltrated at surgical site. The child was extubated, once awake and neuromuscular block was reversed. The video feeds of intubation process were stored in computer and retrospectively reviewed by an independent observer to confirm the observations made by the intubating anesthesiologist.

RESULTS

56 children were included in the study [Table 1]. The youngest child operated for group III cleft was 6 months of age. All intubations were performed by anesthesiologists with experience of successful intubations with Airtraq in 50 adults with normal airways. The purpose was to learn the technique of Airtraq insertion and manipulations to introduce the ETT into the glottis. All intubations, except for one could be successfully performed. The characteristics of the remaining 55 intubations are depicted in Table 2. In 74.55% children, the tube aligned with glottis and intubation could be accomplished without the need for Airtraq manipulations. The Airtraq manipulations, a backup or rotational maneuver were applied in the rest 25.45% with a purpose of positioning the glottis in the center of view.

Table 1

Demographics of patients

Table 2

Intubation characterstics

Statistical analysis

Post hoc power analysis of our study results was performed on ClinCalc software (available at http://clincalc.com/Stats/Power.aspx). The comparative mean for the time taken for intubation was taken from the study by Ali et al.[2] Their mean intubation time with Airtraq in pediatric population was 34.4 ± 7.1 s. Considering an alpha error of 0.05, the power of our study was calculated as 99%.

Power = Φ(−z1− α/2 + |μ0 − μ1 | ×n√/σ)

Where μ0 = population mean, μ1 = mean of study population, n = sample size of study population, σ = variance of study population, α = probability of type I error, z = critical Z value for a given α and Φ = function converting a critical Z value to power.

DISCUSSION

Children with cleft lip and palate often require repeated anesthetics for primary repairs or for procedures to improve lip esthetics, close residual palatal defects, bone grafts to align alveolar and dental defects and correct nasal deformity.

The majority of patients with cleft lip and palate can be intubated with regular laryngoscopes. The incidence of difficult laryngoscopy and intubation was evaluated by Xue et al.[3] They observed a direct relationship between difficult laryngoscopy and infancy, combined bilateral cleft lip and palate and micrognathia.

American Society of Anesthesiology Practice guidelines on airway management published in 2013 have included VL as a primary option or as rescue device for intubation. They have mentioned the advantage of video-assisted techniques in shortening the time in airway management with decreased patient morbidity.[4]

Video laryngoscopes are increasingly getting popular among pediatric anesthesiologists. The percentage of glottis opening scores and visual analogue scores for the field of view were observed to be significantly superior with the Airtraq device in normal pediatric airways.[5] Kalbhenn et al. compared Macintosh size 1 blade to three different optical laryngoscopes for difficult endotracheal intubation (simulation exercise) in infants. Airtraq demonstrated early intubations without dental trauma with a reasonably good success rate in intubations performed by inexperienced users.[6] Successful intubation with Airtraq following failed laryngoscopy as in a 5 months old infant with Pierre Robin sequence[7] and a 3 months old child with occipital meningocele is also reported.[8] A child with Treacher Collins syndrome could be successfully intubated with pediatric Airtraq as a primary intubating device.[9]

Various degrees of anticipated difficulty in establishing an airway in the adult population have been successfully managed with Airtraq.[10] These include patients with a pronounced limitation of cervical mobility,[11] and morbidly obese patients.[5] Airtraq could reduce the duration of intubation attempts, the need for additional maneuvers, intubation difficulty score, the degree of hemodynamic stimulation and resulted in minor trauma compared to the Macintosh laryngoscope.

For pediatric cleft surgeries, RAE tubes are used for intubating the trachea. The RAE tube needs to be temporarily straightened for introducing it into Airtraq. A tube with a preformed bend will be technically difficult to slide down the tube channel of Airtraq. Xue et al. have described a technique in which the portion of tube proximal to bend into the Airtraq.[12] We have modified the technique further by using a malleable stylet to reshape the tube The malleable stylets are easily available in the operation theatres and the limited insertion of stylet prevents airway trauma.

The intubation times with Airtraq in children with normal airways were reported to be longer than conventional laryngoscopy (47.3 vs. 26.3 s).[13] Our mean intubation times (48.02 s) were similar to this study. However, Sørensen and Holm-Knudsen have found Airtraq to be faster than Storz VL in all measured elements of intubation (15.8 vs. 29.0 s) in cleft patients. The type of ETT used was although, not specified in their article.[14]

We have calculated additive intubation times, which could have influenced our mean duration of intubation. Fifteen children in our study have required ≥2 intubation attempts. Airtraq although visualizes the larynx in a nonlinear fashion because of the use of optics, but the tracheal tube is a semi-rigid structure, which has to pass in a linear route from the mouth to the trachea. Hence, despite of a superior laryngeal view using the Airtraq, directing the tracheal tube into the trachea through the glottis is not always straightforward.[15] The cautious insertion to avoid trauma to the cleft and difficulty in maintaining the Airtraq in the center in groups III and IV clefts could have also contributed to longer insertion and intubation times in our study.

The incidence of failed intubation with Airtraq was 1.78% in our study. Intubation had failed in one child with a grade IV cleft. Though the glottis was visualized, the manipulations of Airtraq could not position glottis in the center of viewfinder. The RAE tube repeatedly slipped posteriorly. There was trauma to the airway during the attempts and hence the Airtraq intubation was abandoned. Laryngoscopy was also difficult in this patient as only the posterior commissure was visible and the child was intubated using a pediatric McCoy laryngoscopy and bougie.

Strengthening the Reporting of Observational Studies Epidemiology guidelines are published for encouraging observational research in the field of biomedicine. We have adhered to their recommendations during the preparation of manuscript to ensure an effective research outcome from our single-arm observational study.[16]

CONCLUSION

The presence of cleft did not hamper the passage and positioning of Airtraq. The technique for straightening the preformed bend of RAE tube could allow the use of these tubes with Airtraq for cleft surgeries. There is a learning curve for applications of Airtraq maneuvers for better tube-glottis alignment. Airtraq can be used as a primary intubating device in children with cleft palate with RAE tubes with good overall success rate and low incidence of airway complications.