Modifiable and Nonmodifiable Factors Associated With Perioperative Failure of Extraglottic Airway Devices:

What airway management information do anaesthetic charts prompt for? An audit of charts from 132 hospitals across Australia and New Zealand

Anaesthetists can make safer airway plans if they know which airway techniques worked previously and which ones did not. Anaesthetic charts do not always capture this information, however, and guidelines from the Australian and New Zealand College of Anaesthetists do not specify what details on airway management they should include. To assess how anaesthetic charts support airway documentation, we audited the airway management section of blank charts from 132 hospitals accredited for training by the Australian and New Zealand College of Anaesthetists. We evaluated charts for the presence of 17 clinically important data fields describing tracheal intubation, supraglottic airway use and bag-mask ventilation. Our audit revealed that data fields on anaesthetic charts focus more on tracheal intubation than bag-mask ventilation or supraglottic airway use. Nearly all charts (99%) had prompts for intubation and most had prompts for both operator technique and patient outcome. For supraglottic airway use, 95% of charts had at least one data field, but few had prompts for difficulty or outcome. For bag-mask ventilation, 58% of charts had a data field for difficulty but most of these were subjective; few (1.5%) included any outcome measures. Data fields describing bag-mask ventilation and supraglottic airway use were also inconsistent. In summary, data fields on Australian and New Zealand anaesthetic charts focus on tracheal intubation with consistent prompts for both operator method and outcome. The inclusion of fields for outcome and difficulty of bag-mask ventilation and supraglottic airway use could help clinicians make better records of airway management.

Risk factors for difficult Laryngeal Mask Airway LMA-Supreme™ (LMAS) placement in adults: a multicentric prospective observational study in an Italian population

BACKGROUND

Supraglottic airway devices (SADs) are precious tools for airway management in both routine and rescue situations; few studies have analyzed the risk factors for their difficult insertion.

METHODS

The aim of this study was to identify the risk factors for difficult insertion for a specific SAD, the Laryngeal Mask Airway LMA-Supreme™ (LMAS). This was a prospective multicentric observational study on a cohort of Italian adult patients receiving general anesthesia for elective surgery. The possible causes of difficulty in LMAS placement (difficulty in insertion or unsatisfactory ventilation) were identified based on literature and on the opinion of international airway management experts. A dedicated datasheet was prepared to collect patients' data, including anthropometric-parameters and parameters for the prediction of difficult airway management, as well as technical choices for the use of LMAS. Data were analyzed to discover the risk factors for difficult LMAS placement and the association between each risk factor and the proportion of incorrect positioning was evaluated through the relative risk and its confidence interval.

RESULTS

Four hundred thirty-two patients were enrolled; seventy required two or more attempts to insert the LMAS; nine required a change of strategy. At multivariate analysis, the following factors were significantly associated with difficult LMAS placement: Mallampati III-IV with either phonation or not; inter-incisor distance < 3 cm; reduced neck mobility; no administration of neuromuscular blocking agents (NMBAs).

CONCLUSIONS

The alignment of the laryngeal and pharyngeal axes seems to facilitate the procedure, together with NMBA administration; on the contrary, Mallampati grade III-IV are associated with difficult LMAS placement.

CT imaging of extraglottic airway device-pictorial review

Compared to intubation with a cuffed endotracheal tube, extraglottic airway devices (EGDs), such as laryngeal mask airways, are considered less definitive ventilation conduit devices and are therefore often exchanged via endotracheal intubation (ETI) prior to obtaining CT images. With more widespread use and growing comfort among providers, reports have now described use of EGDs for up to 24 h including cases for which clinicians obtained CT scans with an EGD in situ. The term EGD encompasses a wide variety of devices with more complex structure and CT appearance compared to ETI. All EGDs are typically placed without direct visualization and require less training and time for insertion compared to ETI. While blind insertion generally results in functional positioning, numerous studies have reported misplacements of EGDs identified by CT in the emergency department or post-mortem. A CT-based classification system has recently been suggested to categorize these misplacements in six dimensions: depth, size, rotation, device kinking, mechanical blockage of the ventilation opening(s), and injury from EGD placement. Identifying the type of EGD and its correct placement is critically important both to provide prompt feedback to clinicians and prevent inappropriate medicolegal problems. In this review, we introduce the main types of EGDs, demonstrate their appearance on CT images, and describe examples of misplacements.

Incidence of gastric insufflation at high compared with low laryngeal mask cuff pressure: A randomised controlled cross-over trial

BACKGROUND

The success of ventilation with a laryngeal mask depends crucially on the seal between the mask and the periglottic tissue. Increasing the laryngeal mask's cuff volume is known to reduce oral air leakage but may lead to gastric insufflation.

OBJECTIVE

We hypothesised that a lower cuff pressure would result in less gastric insufflation. We sought to compare gastric insufflation with laryngeal mask cuff pressures of 20 cmH2O (CP20) and 60 cmH2O (CP60) during increasing peak airway pressures in a randomised controlled double-blind cross-over study. We also evaluated the incidence of gastric insufflation at the recommended peak airway pressure of 20 cmH2O or less and during both intermittent positive airway pressure and continuous positive airway pressure.

METHODS

After obtaining ethics approval and written informed consent, 184 patients ventilated via laryngeal mask received a stepwise increase in peak airway pressure from 15 to 30 cmH2O with CP20 and CP60 in turn. Gastric insufflation was determined via real-time ultrasound and measurement of the cross-sectional area of the gastric antrum. The primary endpoint was the incidence of gastric insufflation at the different laryngeal mask cuff pressures.

RESULTS

Data from 164 patients were analysed. Gastric insufflation occurred less frequently at CP20 compared with CP60 (P < 0.0001). Gastric insufflation was detected in 35% of cases with CP20 and in 48% with CP60 at a peak airway pressure of 20 cmH2O or less. Gastric insufflation occurred more often during continuous than during intermittent positive airway pressures (P < 0.01).

CONCLUSION

A laryngeal mask cuff pressure of 20 cmH2O may reduce the risk of gastric insufflation during mechanical ventilation. Surprisingly, peak airway pressure of 20 cmH2O or less may already induce significant gastric insufflation. Continuous positive airway pressure should be avoided due to an increased risk of gastric insufflation.

CLINICAL TRIAL REGISTRATION

The study was registered in the German Clinical Trials Register (DRKS00010583) https://www.drks.de.

Extraglottic Airway Device Misplacement: A Novel Classification System and Findings in Postmortem Computed Tomography

STUDY OBJECTIVE

Extraglottic airway devices are frequently used during cardiac arrest resuscitations and for failed intubation attempts. Recent literature suggests that many extraglottic airway devices are misplaced. The aim of this study is to create a classification system for extraglottic airway device misplacement and describe its frequency in a cohort of decedents who died with an extraglottic airway device in situ.

METHODS

We assembled a cohort of all decedents who died with an extraglottic airway device in situ and underwent postmortem computed tomographic (CT) imaging at the state medical examiner's office during a 6-year period, using retrospective data. An expert panel developed a novel extraglottic airway device misplacement classification system. We then applied the schema in reviewing postmortem CT for extraglottic airway device position and potential complications.

RESULTS

We identified 341 eligible decedents. The median age was 47.0 years (interquartile range 32 to 59 years). Out-of-hospital personnel placed extraglottic airway devices in 265 patients (77.7%) who subsequently died out of hospital; the remainder died inhospital. The classification system consisted of 6 components: depth, size, rotation, device kinking, mechanical blockage of ventilation opening, and injury. Under the system, extraglottic airway devices were found to be misplaced in 49 cases (14.4%), including 5 (1.5%) that resulted in severe injuries.

CONCLUSION

We created a novel extraglottic airway device misplacement classification system. Misplacement occurred in greater than 14% of cases. Severe traumatic complications occurred rarely. Quality improvement activities should include review of extraglottic airway device placement when CT images are available and use the classification system to describe misplacements.

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.

Laryngeal Mask Airway Supreme vs. the Spritztube tracheal cannula in anaesthetised adult patients: A randomised controlled trial

BACKGROUND

The Spritztube is a new supraglottic airway device combining the ability to allow extraglottic ventilation of the lungs with the opportunity to perform fibreoptic-assisted intubation.

OBJECTIVES

To compare the Spritztube tracheal cannula with the Laryngeal Mask Airway Supreme (LMA-S) in anaesthetised adult patients.

DESIGN

A single-centre, randomised controlled study.

SETTING

Tertiary hospital.

PATIENTS

Mechanically ventilated patients undergoing elective surgery in the supine position under general anaesthesia were included. Main exclusion criteria were a history of, or predicted, difficult airway management according to SIAARTI guidelines and absence of written informed consent.

INTERVENTIONS

Patients received the LMA-S or Spritztube tracheal cannula to facilitate ventilation of the lungs.

MAIN OUTCOME MEASURES

Successful placement (primary outcome), time required for insertion, number of attempts, subjective assessment of ease of insertion, safety and incidence of complications were recorded.

RESULTS

One hundred and sixty seven patients were allocated to the LMA-S or Spritztube group, respectively, a total of 334 patients. In the LMA-S group, the device insertion failed in nine patients, compared with none in the Spritztube group (P = 0.002). Spritztube insertion was easy in 100% of cases compared with 94.6% of the cases in the LMA-S group (P = 0.03). The number of attempts was significantly higher with the LMA-S compared with the Spritztube (P = 0.0007), whereas the insertion times were comparable (P = 0.06). Except for the incidence of blood-staining, which was higher in the LMA-S group (P = 0.01), the number of complications was comparable in the two groups.

CONCLUSION

The Spritztube was as effective as the LMA-S in maintaining the airway with all patients being successfully ventilated without difficulty. The success rate of achieving a patent airway was comparable between the groups, with a similar occurrence of complications.

TRIAL REGISTRATION

NCT03443219.