Influence of head and neck position on the performance of supraglottic airway devices: A systematic review and meta-analysis

How does head position affect laryngeal vision with a video laryngeal mask airway?

Background

The Laryngeal Mask Airway Vision Mask (LMA VM) is a supraglottic airway device (SAD) with a vision guidance system. The ideal head and neck position for direct laryngoscopy is known, but the ideal position for placing a LMA is not. The objective of this study is to evaluate and compare the optimal position for placement of a video laryngeal mask airway.

Methods

This prospective, observational, transversal, and analytical study was performed in 72 consecutive patients. In the same patient, laryngeal vision was first assessed with the head and neck in the sniffing position and then with the head in the neutral position. Procedures were performed by the same investigator. The assessment of the laryngeal view was performed using two classifications: Cormack-Lehane classification and Brimacombe classification. The placement of the device was considered adequate when the Cormack-Lehane rating was between 1 and 2 and the Brimacombe rating between 2 and 4.

Results

In this study, 72 patients participated. In the assessment of the glottis using the Cormack-Lehane classification for fibre-optic view, laryngeal visibility was adequate in 64 (88.89%) patients in the neutral position and in 65 (90, 28%) patients in the sniffing position (p > 0.05). In the fibre-optic view of the glottis, evaluated using the Brimacombe classification, laryngeal visibility was adequate in 68 (93%) patients in the neutral position and in 69 (95%) patients in the sniffing position (p > 0.05). There was no statistically significant difference in the rate of success between the sniffing position (70 patients, 97.22% success rate) and the neutral position (67 patients, 93.06% success rate) during the first insertion attempt. Two patients required a second attempt in the sniffing position, while five patients required a second attempt in the neutral position.

Conclusion

An adequate sniffing position did not result in a better glottic view than the neutral position. Additional manoeuvres were equal in both positions. The head-neck position does not influence on the placement of a third-generation SAD.

Comparing leak pressure of LMA® ProSeal™ versus i-gel® at head rotation: a randomized controlled trial

PURPOSE

The effect of head rotation on supraglottic airway (SGA) oropharyngeal leak pressure (OPLP) has not been well elucidated. The aim of this study was to help clarify which SGA device provides higher OPLP at head-rotated position.

METHODS

Patients who underwent elective surgery under general anesthesia were enrolled and randomly divided into laryngeal mask airway (LMA®) ProSeal™ and i-gel® groups. The allocated SGA device was inserted under anesthesia. The primary outcome was OPLP, and secondary outcomes were ventilation score, expiratory tidal volume, and maximum pressure under volume-controlled ventilation (VCV) with an inspiratory tidal volume of 10 mL·kg-1 ideal body weight and fibreoptic view of the vocal cords at 0°, 30°, and 60° head rotation.

RESULTS

Data from 78 and 76 patients were analyzed in the LMA ProSeal and i-gel groups, respectively. The mean (standard deviation) OPLP of the LMA ProSeal was significantly higher than that of the i-gel at the 60° head-rotated position (LMA ProSeal, 20.4 [6.5] vs i-gel, 16.9 [7.8] cm H2O; difference in means, 3.6; adjusted 95% confidence interval, 0.5 to 6.6; adjusted P = 0.02, adjusted for six comparisons). The maximum pressure under VCV at 60° head rotation was significantly higher in the LMA ProSeal group than in the i-gel group. The expiratory tidal volume of the LMA ProSeal did not significantly change with head rotation and was significantly higher than that of the i-gel at 60° head rotation. Ventilation score, fibreoptic view of the vocal cords, and complications were not significantly different between the ProSeal and i-gel groups.

CONCLUSIONS

The LMA ProSeal provides higher OPLP than the i-gel at a 60° head-rotated position under general anesthesia.

TRIAL REGISTRATION

Japan Registry of Clinical Trials (https://jrct.niph.go.jp) (JRCT1012210043); registered 18 October 2021.

Supraglottic Airway Devices with Vision Guided Systems: Third Generation of Supraglottic Airway Devices

Supraglottic airway devices are currently widely used for airway management both for anaesthesia and emergency medicine. First-generation SADs only had a ventilation channel and did not provide protection from possible aspiration of gastric content if regurgitation occurred. Second-generation SADs are equipped with a gastric channel to allow the insertion of a gastric catheter and suctioning of gastric content. Additionally, the seal was improved by a change in the shape of the cuff. Some second-generation SADs were also designed to allow for intubation through the lumen using fiberscopes. Although the safety and efficacy of use of SADs are very high, there are still some issues in terms of providing an adequate seal and protection from possible complications related to misplacement of SAD. New SADs which allow users to choose the insertion scope and control the position of SAD can overcome those problems. Additionally, the Video Laryngeal Mask Airway may serve as an endotracheal intubation device, offering a good alternative to fibre-optic intubation through second-generation SADs. In this narrative review, we provide knowledge of the use of video laryngeal mask airways and the possible advantages of introducing them into daily clinical practice.

Efficacy of laryngeal mask airway against postoperative pharyngolaryngeal complications following thyroid surgery: a systematic review and meta-analysis of randomized controlled studies

This meta-analysis aimed at investigating the effectiveness of laryngeal mask airway (LMA) against postoperative pharyngolaryngeal complications after thyroidectomy. MEDLINE, Cochrane Library, google scholar, and EMBASE databases were searched from inception through February, 2021, for randomized controlled trials (RCTs) comparing the incidence of pharyngolaryngeal complications following the use of LMA or endotracheal tube (ETT). Pooled results from seven RCTs involving 600 patients showed an association of LMA with a reduced risk of postoperative sore throat (POST) at 24 h [risk ratio (RR) 0.75, p = 0.006, four trials], but not at 1 h and 48 h after thyroidectomy. POST severity and hoarseness risk were lower in the LMA group than the ETT group at 1 h, 24 h, and 48 h (all p < 0.05). Nevertheless, hoarseness severity was lower in the LMA group only at postsurgical 48 h [standardized mean difference = - 0.35, p = 0.008, three trials]. Moreover, the risk of emergence cough was lower in patients using LMA than those receiving ETT (RR = 0.14, p = 0.002, two trials). The two groups did not differ in the severity of dysphagia at postoperative 1 h, 24 h, and 48 h. This meta-analysis showed that LMA may be associated with fewer pharyngolaryngeal complications compared to ETT without airway impacts. The limited number of included studies warrants further research to support our findings.

Severe gastric insufflation and consequent atelectasis caused by gas leakage using AIR-Q laryngeal mask airway: A case report

BACKGROUND

The airways of patients undergoing awake craniotomy (AC) are considered “predicted difficult airways”, inclined to be managed with supraglottic airway devices (SADs) to lower the risk of coughing or gagging. However, the special requirements of AC in the head and neck position may deteriorate SADs’ seal performance, which increases the risks of ventilation failure, severe gastric insufflation, regurgitation, and aspiration.

CASE SUMMARY

A 41-year-old man scheduled for AC with the asleep–awake–asleep approach was anesthetized and ventilated with a size 3.5 AIR-Q intubating laryngeal mask airway (LMA). Air leak was noticed with adequate ventilation after head rotation for allowing scalp blockage. Twenty-five minutes later, the LMA was replaced by an endotracheal tube because of a change in the surgical plan. After surgery, the patient consistently showed low tidal volume and was diagnosed with gastric insufflation and atelectasis using computed tomography.

CONCLUSION

This case highlights head rotation may cause gas leakage, severe gastric insufflation, and consequent atelectasis during ventilation with an AIR-Q intubating laryngeal airway.

Head Rotation Reduces Oropharyngeal Leak Pressure of the i-gel and LMA® Supreme™ in Paralyzed, Anesthetized Patients: A Randomized Trial

BACKGROUND

Second-generation supraglottic airway (SGA) devices are useful for airway management during positive pressure ventilation in general anesthesia and emergency medicine. In some clinical settings, such as the anesthetic management of awake craniotomy, SGAs are used in the head-rotated position, which is required for exposure of the surgical field, although this position sometimes worsens the efficiency of mechanical ventilation with SGAs. In this study, we investigated and compared the influence of head rotation on oropharyngeal leak pressures (OPLP) of the i-gel and LMA® Supreme™, which are second-generation SGA devices.

METHODS

Patients who underwent elective surgery under general anesthesia were enrolled in this study and randomly divided into i-gel or LMA Supreme groups. After induction of anesthesia with muscle relaxation, the i-gel or LMA Supreme was inserted according to computerized randomization. The primary outcome was the OPLP at 0°, 30°, and 60° head rotation. The secondary outcomes were the maximum airway pressure and expiratory tidal volume when patients were mechanically ventilated using a volume-controlled ventilation mode with a tidal volume of 10 mL/kg (ideal body weight), ventilation score, and fiber-optic views of vocal cords.

RESULTS

Thirty-four and 36 participants were included in the i-gel and LMA Supreme groups, respectively. The OPLPs of the i-gel and LMA Supreme significantly decreased as the head rotation angle increased (mean difference [95% confidence interval], P value: i-gel; 0° vs 30°: 3.5 [2.2-4.8], P < .001; 30° vs 60°: 2.0 [0.6-3.5], P = .002; 0° vs 60°: 5.5 [3.3-7.8], P < .001, LMA Supreme; 0° vs 30°: 4.1 [2.6-5.5], P < .001; 30° vs 60°: 2.4 [1.1-3.7], P < .001; 0° vs 60°: 6.5 [5.1-8.0], P < .001). There were statistically significant differences in expiratory tidal volume and ventilation score between 0° and 60° in the i-gel group and in ventilation score between 30° and 60° in the LMA Supreme group. There was no statistically significant difference between the 2 devices in all outcome measures. The incidences of adverse events, such as hoarseness or sore throat, were not significantly different between i-gel and LMA Supreme.

CONCLUSIONS

Head rotation to 30° and 60° reduces OPLP with both i-gel and LMA Supreme. There is no difference in OPLP between i-gel and LMA Supreme in the 3 head rotation positions.

Safety, efficacy and airway complications of the flexible laryngeal mask airway in functional endoscopic sinus surgery: A retrospective study of 6661 patients

OBJECTIVES

Although the flexible laryngeal mask airway (FLMA) provides considerable advantages in head and neck procedures, little is known about its safety and efficacy in functional endoscopic sinus surgery (FESS). We conducted a retrospective study to evaluate the success rate of FLMA and relevant airway complications in FESS under general anaesthesia.

METHODS

A retrospective review of consecutive patients who underwent FESS for chronic rhinosinusitis was performed from 2015 to 2019. All patients scheduled for FLMA ventilation were identified. Patient characteristics, length of the surgery, FLMA size, failed FLMA cases requiring endotracheal intubation, immediate adverse airway events and delayed airway injuries were recorded. The primary outcomes included the FLMA success rate, which was defined as primary success after induction and final success after the whole surgical procedure. The secondary outcomes were specific clinical factors associated with FLMA failure and airway complications related to FLMA usage.

RESULTS

Of the 6661 patients included in our study, primary success was achieved in 6572 (98.7%), and final success was achieved in 6512 (97.8%). Failure occurred in 89 patients (1.3%) during induction, in 14 (0.2%) during surgical preparation and in 46 (0.7%) during the intraoperative procedure. All patients with failed FLMA ventilation were successfully switched to endotracheal intubation. Male sex, advanced age, higher American Society of Anesthesiologists grade (ASA) and higher body mass index (BMI) were independent risk factors associated with failed FLMA. Immediate adverse respiratory events were observed in 0.85% of the patients, and delayed airway injuries associated with use of FLMA were observed in 0.07%.

CONCLUSION

This retrospective study demonstrates a high success rate for FLMA (97.8% in 6661 patients undergoing FESS). Adverse airway events and injuries associated with FLMA are rare, but clinicians should remain vigilant so that early diagnosis and prompt treatment can be provided.

Canadian Airway Focus Group updated consensus-based recommendations for management of the difficult airway: part 1. Difficult airway management encountered in an unconscious patient

PURPOSE

Since the last Canadian Airway Focus Group (CAFG) guidelines were published in 2013, the literature on airway management has expanded substantially. The CAFG therefore re-convened to examine this literature and update practice recommendations. This first of two articles addresses difficulty encountered with airway management in an unconscious patient.

SOURCE

Canadian Airway Focus Group members, including anesthesia, emergency medicine, and critical care physicians, were assigned topics to search. Searches were run in the Medline, EMBASE, Cochrane Central Register of Controlled Trials, and CINAHL databases. Results were presented to the group and discussed during video conferences every two weeks from April 2018 to July 2020. These CAFG recommendations are based on the best available published evidence. Where high-quality evidence was lacking, statements are based on group consensus.

FINDINGS AND KEY RECOMMENDATIONS

Most studies comparing video laryngoscopy (VL) with direct laryngoscopy indicate a higher first attempt and overall success rate with VL, and lower complication rates. Thus, resources allowing, the CAFG now recommends use of VL with appropriately selected blade type to facilitate all tracheal intubations. If a first attempt at tracheal intubation or supraglottic airway (SGA) placement is unsuccessful, further attempts can be made as long as patient ventilation and oxygenation is maintained. Nevertheless, total attempts should be limited (to three or fewer) before declaring failure and pausing to consider "exit strategy" options. For failed intubation, exit strategy options in the still-oxygenated patient include awakening (if feasible), temporizing with an SGA, a single further attempt at tracheal intubation using a different technique, or front-of-neck airway access (FONA). Failure of tracheal intubation, face-mask ventilation, and SGA ventilation together with current or imminent hypoxemia defines a "cannot ventilate, cannot oxygenate" emergency. Neuromuscular blockade should be confirmed or established, and a single final attempt at face-mask ventilation, SGA placement, or tracheal intubation with hyper-angulated blade VL can be made, if it had not already been attempted. If ventilation remains impossible, emergency FONA should occur without delay using a scalpel-bougie-tube technique (in the adult patient). The CAFG recommends all institutions designate an individual as "airway lead" to help institute difficult airway protocols, ensure adequate training and equipment, and help with airway-related quality reviews.

Canadian Airway Focus Group updated consensus-based recommendations for management of the difficult airway: part 2. Planning and implementing safe management of the patient with an anticipated difficult airway

PURPOSE

Since the last Canadian Airway Focus Group (CAFG) guidelines were published in 2013, the published airway management literature has expanded substantially. The CAFG therefore re-convened to examine this literature and update practice recommendations. This second of two articles addresses airway evaluation, decision-making, and safe implementation of an airway management strategy when difficulty is anticipated.

SOURCE

Canadian Airway Focus Group members, including anesthesia, emergency medicine, and critical care physicians were assigned topics to search. Searches were run in the Medline, EMBASE, Cochrane Central Register of Controlled Trials, and CINAHL databases. Results were presented to the group and discussed during video conferences every two weeks from April 2018 to July 2020. These CAFG recommendations are based on the best available published evidence. Where high-quality evidence is lacking, statements are based on group consensus.

FINDINGS AND KEY RECOMMENDATIONS

Prior to airway management, a documented strategy should be formulated for every patient, based on airway evaluation. Bedside examination should seek predictors of difficulty with face-mask ventilation (FMV), tracheal intubation using video- or direct laryngoscopy (VL or DL), supraglottic airway use, as well as emergency front of neck airway access. Patient physiology and contextual issues should also be assessed. Predicted difficulty should prompt careful decision-making on how most safely to proceed with airway management. Awake tracheal intubation may provide an extra margin of safety when impossible VL or DL is predicted, when difficulty is predicted with more than one mode of airway management (e.g., tracheal intubation and FMV), or when predicted difficulty coincides with significant physiologic or contextual issues. If managing the patient after the induction of general anesthesia despite predicted difficulty, team briefing should include triggers for moving from one technique to the next, expert assistance should be sourced, and required equipment should be present. Unanticipated difficulty with airway management can always occur, so the airway manager should have a strategy for difficulty occurring in every patient, and the institution must make difficult airway equipment readily available. Tracheal extubation of the at-risk patient must also be carefully planned, including assessment of the patient's tolerance for withdrawal of airway support and whether re-intubation might be difficult.

A multicenter and observational study of the Ambu™ AuraGain™ laryngeal mask in adult patients

PURPOSE

The main objective of this study was to evaluate the performance of the Ambu™ AuraGain™ device by determining its main parameters of use and complications.

METHODS

A total of 250 adult ASA physical status i to iii patients from five hospitals in Spain who received general anaesthesia with a supraglottic airway (SGA) device were enrolled in this study.

RESULTS

The primary outcome was analysed for 244 patients and a median OLP of 32 cm H2O (IQR 28-36 cm H2O) was obtained. Insertion was achieved at first attempt in 85% of cases, and overall in 98% of cases, in a median time of 15 s (12-22.5). We applied manoeuvres in 61% of patients to facilitate the process. Ventilation was effective in 97.2% of the interventions (95% CI 0.99-0.94) throughout the procedure. Insertion of the gastric tube was easily performed in 99.6% of the patients, and the vocal cords were viewed by fibrobronchoscopy in 96.3% of cases. Logistic regression analysis identified the use of sizes smaller than those recommended as a risk factor for low OLP (< 25 cm H2O). The main complication recorded was the presence of blood when withdrawing the SGA device (15%).

CONCLUSIONS

Our results confirm that the use of AuraGain allows airway management in a reliable and effective way achieving high OLP and low incidence of associated complications, establishing it as a useful alternative in the routine clinical setting of anaesthesiologists. AuraGain performance was consistent in all five centres.

Effects of Passive Head-and-Neck Movements on the Performance of i-gel® Supraglottic Airway Device in Anesthetized Patients - A Randomized Crossover Trial

Background:

Passive movements of head and neck are sometimes unavoidable during surgery under general anesthesia due to patient positioning according to the needs of the surgery or transmitted movements from surgical manipulations.

Aims:

This prospective crossover randomized study evaluates the effects of passive movements of the head and neck on the performance of i-gel^® supraglottic airway device in spontaneously breathing patients under general anesthesia.

Materials and Methods:

Sixty spontaneously breathing patients on pressure support ventilation with positive end-expiratory pressure (PEEP) under general anesthesia were randomized to seven sequences of passive head-and-neck movements with i-gel® in situ. After steady state of general anesthesia was achieved and maintenance with sevoflurane in N₂O and O₂ was reached, the passive head-and-neck movements were done. Peak airway pressure, exhaled minute volume, end-tidal carbon dioxide (ETCO₂), oxygen saturation, audible leak of airway gases, and visible outward displacement of the i-gel® were recorded in the neutral position and with each passive head-and-neck movement. Paired continuous data were analyzed by Friedman rank sum test with paired Wilcoxon signed-rank test. Paired nominal data were analyzed by Cochran's Q test with pair-wise McNemar test.

Results:

Extension, right or left lateral flexion, and right or left rotation of the head and neck resulted in significant reduction in the exhaled minute ventilation, rise in ETCO₂, and leak of airway gases compared to the neutral position (P < 0.05). Flexion movement did not cause significant changes in the exhaled minute ventilation, rise in ETCO₂, and audible leak of airway gases as compared to the neutral position.

Conclusions:

Ventilatory performance of the i-gel® deteriorates upon extension, right or left lateral flexion, and right or left rotation of the head and neck in spontaneously breathing patients under general anesthesia on pressure support ventilation with PEEP.