Supraglottic airways in difficult airway management: successes, failures, use and misuse

Incidence of and risk factors for difficult ventilation via a supraglottic airway device in a population of 14,480 patients from South-East Asia

Difficult airway practice guidelines include the use of a supraglottic airway device as part of the armamentarium to provide and maintain ventilation and oxygenation. We retrospectively reviewed 14 480 patients aged ≥ 18 years who underwent general anaesthesia. We identified 74 (0.5%) patients whose lungs were identified as having been difficult to ventilate via a supraglottic airway device, and 29 (0.2%) patients in whom device placement failed. Multivariate analysis identified four risk factors for difficult ventilation via a supraglottic airway device: male sex (OR 1.75, 95% CI 1.07-2.86, p = 0.02); age > 45 years (OR 1.70, 95% CI 1.01-2.86, p = 0.04); short thyromental distance (OR 4.35, 95% CI 2.31-8.17, p < 0.001); and limited neck movement (OR 2.75, 95% CI 1.02-7.44, p = 0.04). Adverse respiratory events including oxygen desaturation, hypercapnoea, laryngospasm, and bronchospasm occurred in 17 patients (22%). The incidence of difficult ventilation via a supraglottic airway device was 0.5% in a large cohort of South-East Asian patients.

Airway management evolution - in a search for an ideal extraglottic airway device

Extraglottic airway devices (EADs) are commonly used equipment for airway maintenance during elective procedures under general anaesthesia. They may be used also in other indications such as conduit for tracheal intubation or rescue airway device in prehospital medicine. Current classifications of the EADs lack systematic approach and therefore classification according to the sealing sites and sealing mechanisms is suggested in this review article. Modern EADs are disposable, latex-free devices made of plastic materials most commonly from polyvinylchloride (PVC). The bowl of uncuffed sealers is manufactured from different materials such as thermoplastic elastomers or ethylene-vinyl-acetate co-polymer. EADs create various physical forces exerted on the adjacent tissues which may contribute to different sealing characteristic of particular device or to variable incidence of postoperative complications. Desired features of an ideal EAD involve easy insertion, high insertion success rate even by inexperienced users, protection against aspiration of gastric contents and low incidence of postoperative complications such as sore throat, hoarseness, cough or swallowing difficulties.

An update on newer pediatric supraglottic airways with recommendations for clinical use

Supraglottic airways are an established part of routine and emergency pediatric airway management, including use in difficult airways and neonatal resuscitation. With the introduction of newer supraglottic airways in children, efficacy can only be determined by comparing these devices with those that are already well established (laryngeal mask airway Classic and laryngeal mask airway ProSeal). This narrative review aims to present the current literature on these newer supraglottic airways and give recommendations for their use in various clinical scenarios based on the existing evidence.

Comparison of the i-gel and the laryngeal mask airway proseal during general anesthesia: a systematic review and meta-analysis

Objectives

Conflicting results have been reported for the i-gel and the laryngeal mask airway proseal (LMA-P) during general anesthesia. The objective of the current investigation was to compare the efficacy and safety of the i-gel vs. the LMA-P during general anesthesia.

Methods

Two authors performed searches of MEDLINE, EMBASE, CENTRAL, and Google Scholar to identify randomized clinical trials that compared the LMA-P with the i-gel during general anesthesia. A meta -analysis was performed using both random and fixed-effect models. Publication bias was evaluated using Begg's funnel plot and Egger's linear regression test.

Results

Twelve randomized clinical trials met the eligibility criteria. There were no significant differences in insertion success rate at the first attempt (risk ratio [RR] 1.01, 95% confidence interval [CI] 0.97, 1.06), ease of insertion (RR 1.14, 95% CI 0.93, 1.39), oropharyngeal leak pressure (OLP) (MD -1.98, 95% CI -5.41, 1.45), quality of fiberoptic view (RR 1.00, 95% CI 0.91, 1.10) and success rate of gastric tube insertion (RR 1.07, 95% CI 0.98, 1.18) between the i-gel and the LMA-P, respectively. The i-gel had a shorter insertion time than the LMA-P (MD -3.99, 95% CI -7.13, -0.84) and a lower incidence of blood staining on the device (RR 0.26, 95% CI 0.14, 0.49), sore throat (RR 0.28, 95% CI 0.15, 0.50) and dysphagia (RR 0.27, 95% CI 0.10, 0.74).

Conclusions

Both devices were comparable in ease of insertion to insert and both had sufficient OLP to provide a reliable airway. Only a few minor complications were reported. The i-gel was found to have fewer complications (blood staining, sore throat, dysphagia) than the LMA-P and offers certain advantages over the LMA-P in adults under general anesthesia.

Tracheal Intubation with Aura-i and aScope-2: How to Minimize Apnea Time in an Unpredicted Difficult Airway

The supraglottic airway's usefulness as a dedicated airway is the subject of continuing development. We report the case of an obese patient with unpredicted difficult airway management in which a new “continuous ventilation technique” was used with the Aura-i laryngeal mask and the aScope-2 devices. The aScope-2/Aura-i system implemented airway devices for the management of predictable/unpredictable difficult airway. The original technique required the disconnection of the mount catheter from Aura-i, the introduction of the aScope-2 into the laryngeal mask used as a conduit for video assisted intubation and then towards the trachea, followed by a railroading of the tracheal tube over the aScope-2. This variation in the technique guarantees mechanical ventilation during the entire procedure and could prevent the risk of hypoventilation and/or hypoxia.

A new strategy for difficult airway management with visual needle cricothyroidotomy: a manikin study

BACKGROUND

Conventional needle cricothyroidotomy uses blind manipulation. We investigated the feasibility and efficiency of a new visually guided needle cricothyroidotomy technique.

METHODS

A 0.9-mm microimaging fiber was delivered into a 14G needle to develop a visual puncture system. 10 inexperienced physicians were randomly assigned to perform 10 repeated needle cricothyroidotomy in each group with both conventional method and visual puncture in a manikin. Tracheal lumen puncture time and number of procedure-related complications were recorded.

RESULTS

Under visual guidance, the needle successfully reached the tracheal lumen. The anatomy of the upper and lower airways was acquired by further advancing the microimaging fiber into the tracheal lumen of the visual group. The tracheal lumen puncture time was significantly less in the visual group than in the conventional group (3.85 ± 1.54 vs. 9.84 ± 1.08 seconds, P < .001). Damage to the posterior tracheal wall was not observed in the visual group; however, 21% of manikins in the conventional group had procedure-related complications.

CONCLUSIONS

Our results demonstrate that visual needle cricothyroidotomy is feasible, and may lead to a decrease in procedure time and procedure-related complications compared to the conventional procedure. In addition, this strategy may also provide useful information for diagnostic purposes; therefore, visual needle cricothyroidotomy may be a new strategy for the management of difficult airways in future care.

A randomised comparison of free-handed vs air-Q assisted fibreoptic-guided tracheal intubation in children < 2 years of age

We prospectively compared free-handed and air-Q™ assisted fibreoptic-guided tracheal intubation in children < 2 years of age. Eighty healthy children were enrolled and randomly assigned to a technique (free-handed or air-Q assisted) and operator (trainee or attending). Time, number of attempts and manoeuvres required were assessed. There was no difference in median (IQR [range]) time to successful tracheal intubation between the free-handed (52.2 (34.8-67.7 [19.7-108.0]) s), and the air-Q assisted (60.3 (45.5-75.1 [28.1-129.0]) s; p = 0.13) groups, or the number of attempts needed. The air-Q assisted group required fewer manoeuvres to optimise the laryngeal view (median (IQR [range]) 0 (0-1 [0-2])) than the free-handed group (1 (1-1 [0-3]); p < 0.001). In conclusion, fibreoptic-guided tracheal intubation times were similar with and without the use of the air-Q, but supraglottic airway devices may be a consideration for their other practical advantages.

A comparative study among normal saline, water soluble gel and 2% lidocaine gel as a SLIPA lubricant

BACKGROUND

This study was designed to find appropriate lubricant for streamed lined liner of pharyngeal airway™ (SLIPA™). We evaluated the incidence of sore throat, nausea, vomiting, hoarseness, paresthesia and blood stain after using saline, water soluble gel and 2% lidocaine gel as a SLIPA™ lublicant.

METHODS

One hundred twenty three patients scheduled for minor surgery to whom the SLIPA™ was considered suitable were randomly allocated to one of three groups which receive normal saline, water soluble gel or 2% lidocaine gel as a SLIPA™ lublicant. Patients were interviewed at recovery room, post operation 6-12 hour, post operation 18-24 hour about sore throat and other complications.

RESULTS

There were no statistical difference in sore throat and blood stain among three groups. Also there were no statistical differences in hoarseness, nausea, vomiting. The incidence of paresthesia in 2% lidocaine gel group was significantly higher than those of the other two groups immediately after operation, but it was resolved after leaving the recovery room.

CONCLUSIONS

Our results suggest that normal saline, water soluble gel and 2% lidocaine gel are all available as a SLIPA™ lubricant. Size of SLIPA™, insertion technique and difficulty of insertion should be further investigated as the main causes of a sore throat and other complications which can occur after the insertion of SLIPA™.

Utility of the Aintree Intubation Catheter in fiberoptic tracheal intubation through the three types of intubating supraglottic airways: a manikin simulation study

Purpose

The purpose of this study was to examine the utility of the Aintree Intubation Catheter (AIC) with three types of supraglottic airway devices for tracheal intubation (ISGAs) using a manikin.

Methods

Participants were 21 anesthesiologists with more than 2 years of experience in clinical anesthesia. Three types of ISGAs were passed through the glottis: Fastrack-Single Use (FSU; size 4), air-Q (size 3.5), and i-gel (size 4). Participants attempted fiberoptic tracheal intubation with the ISGAs in random order. Success rate of tracheal intubation, intubation time, and collision with the glottis were recorded. Participants also evaluated the subjective difficulty of the entire intubation process and passing the tracheal tube through the glottis using a Visual Analogue Scale.

Results

The FSU required a significantly longer time for intubation compared with the other two ISGAs (p < 0.05). AIC use did not significantly improve the success rate of intubation or shorten intubation times for any of the ISGAs. However, there were significantly more collisions with the glottis without AIC use for the FSU and air-Q compared to when they were used with the AIC (FSU, p = 0.015; air-Q, p = 0.025).

Conclusion

Among the ISGAs tested, intubation took longer with the FSU, and the FSU had a higher failure rate than the other ISGAs. AIC significantly decreased the number of collisions with the FSU and air-Q. These findings suggest that the AIC is effective in reducing collisions with the tracheal tube and thus will reduce the risk of mechanical injury to the airway.

Transfer of airway skills from manikin training to patient: success of ventilation with facemask or LMA-Supreme(TM) by medical students

During emergency care, the ability to ventilate the patient's lungs is a crucial skill. Supraglottic airway devices have an established role in emergency care, and manikin trials have shown that placement is easy even for inexperienced users. However, there is current discussion as to what extent these results can be transferred to patients. We studied the transfer of skills learnt on a manikin to the clinical situation in novice medical students during their anaesthesia rotation. They were required to ventilate the lungs of a manikin using a facemask and then position a supraglottic airway device (LMA-Supreme™) and ventilate the lungs. This process was then repeated on anaesthetised patients, with standard ventilator settings to assess adequacy of ventilation. Sixty-three students participated in the manikin study. The success rate for ventilating the lungs was 100% for both devices, but the mean (SD) time to achieve successful ventilation was 27.8 (24.4) s with the facemask compared with 38.6 (22.0) s with the LMA-Supreme (p = 0.008). Fifty-one of the students progressed to the second part of the study. In anaesthetised patients, the success rate for ventilating the lungs was lower for the facemask, 27/41 (66%) compared with the LMA-Supreme 37/41 (90%, p = 0.006). For 26 students who succeeded with both devices, the tidal volume was lower using the facemask, 431 (192) ml compared with the LMA-Supreme 751 (221) ml (p = 0.001), but the time to successful ventilation did not differ, 60.0 (26.2) s vs 57.3 (26.6) s (p = 0.71). We conclude that the results obtained in manikin studies cannot be transferred directly to the clinical situation and that guidelines should take this into account. Based on our findings, a supraglottic airway device may be preferable to a facemask as the first choice for inexperienced emergency caregivers.

[Supraglottic airway devices in emergency medicine : impact of gastric drainage]

This case report describes a life-saving use of a supraglottic airway device (LT-D™-Larynxtubus, VBM Medizintechnik, Sulz, Germany) in an out-of-hospital emergency patient suffering from severe traumatic brain injury. Mechanical ventilation with the laryngeal tube was complicated by repeated airway obstructions and pronounced gastric distension with air as a consequence of oropharyngeal leakage. In this situation pulmonary ventilation of the patient was compromised so that emergency endotracheal intubation became necessary in the resuscitation area with vital indications. In this context the status of supraglottic airway devices in emergency medicine is discussed as well as the reasons for the gastric distension. Besides the immediate drastic consequences of gastric distension with respect to pulmonary ventilation, potential deleterious non-pulmonary consequences of this complication are highlighted. The clinical relevance of the described complications as well as the associated possibility of an optimized position control necessitate the recommendation only to use second generation supraglottic airway devices with integrated gastric access in (out-of-hospital) emergency medicine.

Longitudinal and regional trends in paramedic student exposure to advanced airway placement: 2001-2011

OBJECTIVES

The primary aims of this study were to determine whether the frequency of placement, type of advanced airway, and settings of advanced airway placement (clinical vs. field) have changed for paramedic students over the last 11 years, and to describe regional differences regarding the same set of variables.

METHODS

This study was a retrospective review of prospectively reported airway procedures documented by paramedic students in Fisdap ( http://www.fisdap.net ). Students were included if they graduated from a paramedic program, had procedure entries verified by a preceptor, and provided consent for research. Exclusion criteria included students who had a total number of airway placements ≥2 standard deviations from the mean or had 0 airway placements recorded, and programs with <10 graduating students total over the study period. Airway device types and educational settings were descriptively compared over the 11-year study period by year and region.

RESULTS

A total of 8,934 paramedic student records were reviewed, with 2,811 excluded based on a priori criteria, leaving 6,123 records for analysis. In each year, the median number of airway devices placed per student was greater in the clinical setting. Endotracheal intubation (ETI) was more common than alternative airway placement in both the field and clinical settings. The median number of clinical ETIs per student has remained relatively constant at 7. The median number of field ETIs per student ranged from 0 to 1 over the study period, with a median alternative airway placement rate of 0 for both clinical and field settings. For all regions, the majority of procedures were performed in a clinical environment. The median number of clinical alternative airway device placements was 0 for all regions. The number of clinical ETIs ranged from 5 to 11 per student, with the highest number of ETIs per student in the West North Central and New England regions and the lowest in the West South Central and East South Central regions.

CONCLUSION

Paramedic students gain the majority of their advanced airway experience in the clinical setting. ETI remains more common than alternative airway placement, although there is significant geographic variation in the number of ETIs per student. High rates of clinical intubations do not correlate with high rates of field intubations.

Pediatric airway management: current practices and future directions

Management of a pediatric airway can be a challenge, especially for the non-pediatric anesthesiologists. Structured algorithms for an unexpected difficult pediatric airway have been missing so far. A recent step wise algorithm, based on the Difficult Airway society (DAS) adult protocol, is a step in the right direction. There have been some exciting advances in development of pediatric extra-glottic devices for maintaining ventilation, and introduction of pediatric versions of new 'non line of sight' laryngoscopes and optical stylets. The exact role of these devices in routine and emergent situations is still evolving. Recent advances in simulation technology has become a valuable tool in imparting psychomotor and procedural skills to trainees and allied healthcare workers. Moving toward the goal of eliminating serious adverse events during the management of routine and difficult pediatric airway, authors propose that institutions develop a dedicated Difficult Airway Service comprising of a team of experts in advanced airway management.