Progress in management of the obstructed airway

Executive Summary of the Spanish Society of Anesthesiology, Reanimation and Pain Therapy (SEDAR) Spanish Society of Emergency and Emergency Medicine (SEMES) and Spanish Society of Otolaryngology, Head and Neck Surgery (SEORL-CCC) Guideline for difficult airway management

The Airway section of the Spanish Society of Anesthesiology, Reanimation and Pain Therapy (SEDAR), Spanish Society of Emergency and Emergency Medicine (SEMES) and Spanish Society of Otolaryngology, Head and Neck Surgery (SEORL-CCC) present the Guidelines for the integral management of difficult airway in adult patients. This document provides recommendations based on current scientific evidence, theoretical-educational tools and implementation tools, mainly cognitive aids, applicable to the treatment of the airway in the field of anesthesiology, critical care, emergencies and prehospital medicine. Its principles are focused on the human factors, cognitive processes for decision-making in critical situations and optimization in the progression of the application of strategies to preserve adequate alveolar oxygenation in order to improve safety and quality of care.

Spanish Society of Anesthesiology, Reanimation and Pain Therapy (SEDAR), Spanish Society of Emergency and Emergency Medicine (SEMES) and Spanish Society of Otolaryngology, Head and Neck Surgery (SEORL-CCC) Guideline for difficult airway management. Part II

The Airway Management section of the Spanish Society of Anesthesiology, Resuscitation, and Pain Therapy (SEDAR), the Spanish Society of Emergency Medicine (SEMES), and the Spanish Society of Otorhinolaryngology and Head and Neck Surgery (SEORL-CCC) present the Guide for the comprehensive management of difficult airway in adult patients. Its principles are focused on the human factors, cognitive processes for decision-making in critical situations, and optimization in the progression of strategies application to preserve adequate alveolar oxygenation in order to enhance safety and the quality of care. The document provides evidence-based recommendations, theoretical-educational tools, and implementation tools, mainly cognitive aids, applicable to airway management in the fields of anesthesiology, critical care, emergencies, and prehospital medicine. For this purpose, an extensive literature search was conducted following PRISMA-R guidelines and was analyzed using the GRADE methodology. Recommendations were formulated according to the GRADE methodology. Recommendations for sections with low-quality evidence were based on expert opinion through consensus reached via a Delphi questionnaire.

Lipid emulsion facilitates reversal from volatile anesthetics in a rodent model

BACKGROUND

Lipid emulsion infusion is a first-line therapy against the toxicity of local anesthetics and is a potential treatment for other drug overdoses, especially for highly lipophilic drugs. Considering the lipophilic property of volatile anesthetics, we hypothesized that lipid emulsion could reverse general anesthesia.

METHODS

Using adult rats, we tested the effect of lipid emulsion infusion on time to emergence after discontinuation of sevoflurane and isoflurane, and further evaluated restoration of righting reflex under continuous sevoflurane anesthesia. Electroencephalogram during lipid emulsion infusion was also investigated under continuous sevoflurane inhalation. The effect of lipid emulsion on sevoflurane-induced respiratory and hemodynamic depressions was evaluated by measuring respiratory rate, PaCO₂ (arterial partial pressure of CO₂), blood pressure, and heart rate. The binding property of lipid emulsion on sevoflurane and isoflurane was assessed using in vitro setting with a conical flask.

RESULTS

Lipid emulsion infusion significantly decreased time to emergence from sevoflurane anesthesia (131 ± 53 vs. 237 ± 69 s) and restored righting reflex during continuous sevoflurane inhalation, by comparing normal saline infusion. Consistent with the behavioral findings, the electroencephalogram under continuous sevoflurane showed decreased power of the δ bands at 5 min after the initiation of lipid emulsion infusion. In addition to reversing hypnosis, lipid emulsion recovered respiratory as well as hemodynamic depressions induced by sevoflurane. Decreased time to emergence was observed also in isoflurane anesthesia (203 ± 111 vs. 314 ± 154 s). To investigate the binding mechanism of lipid emulsion infusion, in vitro experiments revealed significantly decreased anesthetic concentrations of sevoflurane and isoflurane by mixing with lipid emulsion.

CONCLUSIONS

Lipid emulsion facilitated reversal from volatile anesthetics, as shown by several parameters. As lipid emulsion could bind to volatile anesthetics and simply decrease their effects, our findings suggest that lipid emulsion is a potentially useful agent to reverse general anesthesia.

Rapid upper airway obstruction after arteriovenous malformation rupture in a patient with neurofibromatosis

Neurofibromatosis type 1 is rarely associated with arteriovenous malformation rupture. We present a case of a rapidly compromised upper airway due to extrinsic compression as a consequence of the rupture of an arteriovenous malformation fed by the inferior thyroid artery which required emergency cricothyroidotomy following failed attempts at orotracheal intubation. While the patient had a good overall outcome, our reflection on the management of this case highlights several important learning points. These include the importance of clear communication between different medical specialties to promote shared situation awareness, the importance of training anaesthetists in the limitations of standard difficult airway management algorithms, and the implications of the skillset mix of doctors responding to airway emergencies in district general hospitals.

Transtracheal jet ventilation in a general tertiary hospital: A 7-year audit

Airway management in patients presenting with severe airway obstruction can present a challenge to the anaesthetist, as conventional difficult airway pathways are often inappropriate. The use of a transtracheal jet cannula is an alternative means of airway securement, but lack of familiarity has limited its use in general tertiary hospitals. We report a retrospective audit of the use of transtracheal jet ventilation in a general tertiary healthcare centre over the past seven years, with a total of 50 patients with severe airway compromise undergoing pharyngolaryngeal surgery. Transtracheal jet ventilation was successful in 98% of patients, and was the definitive means of airway management in 43 cases. In six cases, the technique was a useful temporising measure while the airway was secured by other means. Minor complications occurred in 12% of patients. No major morbidities or mortalities were recorded. We conclude that transtracheal jet ventilation for high-risk pharyngolaryngeal surgery can be performed using a high frequency jet ventilator, with a high rate of success and only minor complications. Cannulation of the trachea below the cricothyroid membrane is feasible but more challenging. Low-flow apnoeic oxygenation through the transtracheal jet ventilation cannula maintains oxygenation during initial surgical airway manipulation.

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.

Acute presentation of a partially obstructing laryngeal tumour: adjuvant agents to gaseous induction of anaesthesia

We present the case of a 53-year-old man who attended our emergency department with stridor. He had recently undergone investigation for possible glottic cancer. We discuss the airway management of such a case. We believe this to be the first description of propofol target controlled infusion and clonidine to supplement a sevoflurane gas induction, in order to obtund response to intubation while maintaining spontaneous ventilation. We also consider how airway interventions may impact prognosis and need to be considered.

Noninvasive Ventilation as a Temporizing Measure in Critical Fixed Central Airway Obstruction: A Case Report

BACKGROUND

Critical central airway obstruction (CAO) requires emergent airway intervention, but current guidelines lack specific recommendations for airway management in the emergency department (ED) while awaiting rigid bronchoscopy. There are few reports of the use of noninvasive ventilation (NIV) in tracheomalacia, but its use as a temporizing treatment option in fixed, malignant CAO has not, to the best of our knowledge, been reported.

CASE REPORT

An 84-year-old woman presented to the ED in respiratory distress, too breathless to speak and using her accessory muscles of respiration, with bilateral rhonchi throughout the lung fields. Point-of-care arterial blood gas revealed severe hypercapnia, and NIV was initiated to treat a presumed bronchitis with hypercapnic respiratory failure. Chest radiography revealed a paratracheal mass with tracheal deviation and compression. A diagnosis of critical CAO was made. While arranging for rigid bronchoscopic stenting, the patient was kept on NIV to good effect. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: Recommendations for emergent treatment of life-threatening, critical CAO before bronchoscopic intervention are not well established. Furthermore, reports of NIV use in CAO are rare. We suggest that emergency physicians consider NIV as a temporizing measure for critical CAO while awaiting availability of bronchoscopy.

Spontaneous Respiration Using Intravenous Anesthesia and High-Flow Nasal Oxygen (STRIVE Hi) Management of Acute Adult Epiglottitis: A Case Report

High-flow nasal oxygen (HFNO) is a potentially life-saving adjunct in the emergency management of the obstructed airway. HFNO has multiple beneficial applications in critical care and respiratory support, but its use in emergency-obstructed airway management has not been defined. This case report describes spontaneous respiration using intravenous anesthesia and high-flow nasal oxygen to successfully manage acute adult epiglottitis with rapidly progressing airway obstruction. Oxygenation, carbon dioxide levels, and airway patency were maintained, which facilitated endotracheal intubation while the patient was spontaneously breathing during general anesthesia. The application of HFNO can be extended to emergency airway obstruction.

Guidelines for the management of tracheal intubation in critically ill adults

These guidelines describe a comprehensive strategy to optimize oxygenation, airway management, and tracheal intubation in critically ill patients, in all hospital locations. They are a direct response to the 4^th National Audit Project of the Royal College of Anaesthetists and Difficult Airway Society, which highlighted deficient management of these extremely vulnerable patients leading to major complications and avoidable deaths. They are founded on robust evidence where available, supplemented by expert consensus opinion where it is not. These guidelines recognize that improved outcomes of emergency airway management require closer attention to human factors, rather than simply introduction of new devices or improved technical proficiency. They stress the role of the airway team, a shared mental model, planning, and communication throughout airway management. The primacy of oxygenation including pre- and peroxygenation is emphasized. A modified rapid sequence approach is recommended. Optimal management is presented in an algorithm that combines Plans B and C, incorporating elements of the Vortex approach. To avoid delays and task fixation, the importance of limiting procedural attempts, promptly recognizing failure, and transitioning to the next algorithm step are emphasized. The guidelines recommend early use of a videolaryngoscope, with a screen visible to all, and second generation supraglottic airways for airway rescue. Recommendations for emergency front of neck airway are for a scalpel-bougie-tube technique while acknowledging the value of other techniques performed by trained experts. As most critical care airway catastrophes occur after intubation, from dislodged or blocked tubes, essential methods to avoid these complications are also emphasized.

Incomplete Spontaneous Recovery from Airway Obstruction During Inhaled Anesthesia Induction: A Computational Simulation

BACKGROUND

Inhaled induction with spontaneous respiration is a technique used for difficult airways. One of the proposed advantages is if airway patency is lost, the anesthetic agent will spontaneously redistribute until anesthetic depth is reduced and airway patency can be recovered. There are little and conflicting clinical or experimental data regarding the kinetics of this anesthetic technique. We used computer simulation to investigate this situation.

METHODS

We used GasMan, a computer simulation of inhaled anesthetic kinetics. For each simulation, alveolar ventilation was initiated with a set anesthetic induction concentration. When the vessel-rich group level reached the simulation specified airway obstruction threshold, alveolar ventilation was set at 0 to simulate complete airway obstruction. The time until the vessel-rich group anesthetic level decreased below the airway obstruction threshold was designated time to spontaneous recovery. We varied the parameters for each simulation, exploring the use of sevoflurane and halothane, airway obstruction threshold from 0.5 to 2 minimum alveolar concentration (MAC), anesthetic induction concentration 2 to 4 MAC sevoflurane and 4 to 6 MAC halothane, cardiac output 2.5 to 10 L/min, functional residual capacity 1.5 to 3.5 L, and relative vessel-rich group perfusion 67% to 85%.

RESULTS

In each simulation, there were 3 general phases: anesthetic wash-in, obstruction and overshoot, and then slow redistribution. During the first 2 phases, there was a large gradient between the alveolar and vessel-rich group. Alveolar do not reflect vessel-rich group anesthetic levels until the late third phase. Time to spontaneous recovery varied between 35 and 749 seconds for sevoflurane and 13 and 222 seconds for halothane depending on the simulation parameters. Halothane had a faster time to spontaneous recovery because of the lower alveolar gradient and less overshoot of the vessel-rich group, not faster redistribution. Higher airway obstruction thresholds, decreased anesthetic induction, and higher cardiac output reduced time to spontaneous recovery. To a lesser effect, decreased functional residual capacity and the decreased relative vessel-rich groups' perfusion also reduced the time to spontaneous recovery.

CONCLUSIONS

Spontaneous recovery after complete airway obstruction during inhaled induction is plausible, but the recovery time is highly variable and depends on the clinical and physiologic situation. These results emphasize that induction is a non-steady-state situation, thus effect-site anesthetic levels should be modeled in future research, not alveolar concentration. Finally, this study provides an example of using computer simulation to explore situations that are difficult to investigate clinically.

Successful intubation of a difficult airway due to a large obstructive vocal cord polyp augmented by the delivery of a transtracheal injection of local anaesthetic

We describe a case of a very difficult intubation which was safely navigated through careful planning. Our patient presented initially with increasing hoarseness and shortness of breath over a 6-month period. This was investigated and the patient was found to have a large vocal cord mass and was referred for urgent microlaryngoscopy and vocal cord polypectomy. On the day of surgery the obstruction was noted and awake fiberoptic bronchoscopy was used with a remifentanil infusion. Given the mass was large and increased in size with expiration, the time frame to pass the tube was extremely short. We delivered a transtracheal injection of local anaesthesia. This approach allowed for safe passage of the endotracheal tube. In patients such as this it may be worth considering the use of a transtracheal injection in the first instance.

Head and neck surgery in a tertiary centre: Predictors of difficult airway and anaesthetic management

Introduction:

The management of head and neck surgical patients is associated with increased morbidity and mortality, and so anticipating the difficult airway is important.

Methods:

We undertook a prospective survey on consecutive adult patients scheduled on the elective operating lists of four head and neck consultant surgeons. Data were collected over a 36 month period. Data included: patient characteristics; routine predictors of difficulty in airway management (bedside tests of the airway, a history of previous surgery or radiotherapy and the presence of airway symptoms); laryngoscopy grade; method of anaesthesia and airway management; and any airway complications arising during induction of anaesthesia and extubation.

Results:

The ‘study’ group consisted of 818 patients. The ‘direct laryngoscopy’ group contained 674 patients, that is, patients who had direct laryngoscopy and could therefore be classified as easy or difficult intubation. The prevalence of difficult intubation was 12.6%. Factors or tests that were statistically significantly associated with difficult intubation were: history of difficult airway; previous head or neck radiotherapy treatment; presence of airway symptoms; presence of moderate or severe limited neck movement; and short interdental distance. The sensitivity, specificity and positive predictive values were: history of difficult airway 16.5%, 98.6% and 63.6%; previous radiotherapy 12.9%, 96.6% and 35.5%; airway symptoms 42.9%, 69.6% and 15.9%; moderate/severe neck limitation 16.7%, 97.2% and 46.7%; Mallampati score 3 or 4, 38.8%, 83.8% and 25.8%; and interdental distance 9.4%, 98.8% and 53.3%, respectively. The Bonfils intubation fibrescope was the most commonly used indirect laryngoscopy device (63.9% of all such cases). Twenty-six patients (3.2%) had complications during their initial airway management after induction of anaesthesia. There was one case of ‘cannot intubate, cannot oxygenate’, which required an emergency tracheostomy.

Conclusion:

The prevalence of difficult intubation in head and neck surgical patients was higher than in the general population, but predictive tests for difficult intubation have poor to moderate value. In our study, rates of difficult face mask ventilation, failed intubation and complications during induction and extubation were low. However, serious morbidity, although rare, can still be encountered. Head and neck surgical patients can be managed safely in a tertiary centre where there is appropriate surgical and anaesthetic expertise in managing difficult airways.

Predictors of difficult intubation and the otolaryngology perioperative consult

Airway management is one of the most important aspects of anesthesia care. Although the incidence of difficult intubation is low, predicting a potentially difficult airway can ensure that necessary staff and equipment are available. A preoperative airway evaluation should include a history and physical examination focusing on elements that can cause problems with intubation. When indicated, flexible fiberoptic laryngoscopy can add valuable information regarding the upper aerodigestive anatomy. Specific patient and situational factors should be considered. Alternative plans should be defined before the initiation of anesthesia. Management of a complex airway should be a coordinated effort between anesthesiologists and otolaryngologists.

The difficult airway with recommendations for management--part 2--the anticipated difficult airway

BACKGROUND

Appropriate planning is crucial to avoid morbidity and mortality when difficulty is anticipated with airway management. Many guidelines developed by national societies have focused on management of difficulty encountered in the unconscious patient; however, little guidance appears in the literature on how best to approach the patient with an anticipated difficult airway.

METHODS

To review this and other subjects, the Canadian Airway Focus Group (CAFG) was re-formed. With representation from anesthesiology, emergency medicine, and critical care, CAFG members were assigned topics for review. As literature reviews were completed, results were presented and discussed during teleconferences and two face-to-face meetings. When appropriate, evidence- or consensus-based recommendations were made, and levels of evidence were assigned.

PRINCIPAL FINDINGS

Previously published predictors of difficult direct laryngoscopy are widely known. More recent studies report predictors of difficult face mask ventilation, video laryngoscopy, use of a supraglottic device, and cricothyrotomy. All are important facets of a complete airway evaluation and must be considered when difficulty is anticipated with airway management. Many studies now document the increasing patient morbidity that occurs with multiple attempts at tracheal intubation. Therefore, when difficulty is anticipated, tracheal intubation after induction of general anesthesia should be considered only when success with the chosen device(s) can be predicted in a maximum of three attempts. Concomitant predicted difficulty using oxygenation by face mask or supraglottic device ventilation as a fallback makes an awake approach advisable. Contextual issues, such as patient cooperation, availability of additional skilled help, and the clinician's experience, must also be considered in deciding the appropriate strategy.

CONCLUSIONS

With an appropriate airway evaluation and consideration of relevant contextual issues, a rational decision can be made on whether an awake approach to tracheal intubation will maximize patient safety or if airway management can safely proceed after induction of general anesthesia. With predicted difficulty, close attention should be paid to details of implementing the chosen approach. This should include having a plan in case of the failure of tracheal intubation or patient oxygenation.

Conscious sedation for awake fibreoptic intubation: a review of the literature

PURPOSE

Awake fibreoptic intubation (AFOI) is the gold standard of management of the predicted difficult airway. Sedation is frequently used to make the process more tolerable to patients. It is not always easy to strike a balance between patient comfort and good intubating conditions on the one hand and maintaining ventilation and a patent airway on the other. In the last 30 years, many drugs and drug combinations have been described, but there is very little in the literature to help guide the practitioner to choose between them. The objective of this article is to discuss the evidence supporting the use of the agents described with regard to their efficacy, recommended doses and techniques, and limitations to their use for AFOI.

SOURCE

Publication databases were searched for articles published from 1996 to 2012 relating to sedation for AFOI.

PRINCIPLE FINDINGS

Benzodiazepines, propofol, opioids, alpha2-adrenoceptor agonists, and ketamine are the main classes of drugs that have been described to facilitate AFOI. Drugs that are most suitable have a combination of both anxiolytic and analgesic properties. The ideal choice of drug may vary depending on the patient and the indication for AFOI.

CONCLUSION

There is good evidence to support the use of two drugs in particular, remifentanil and dexmedetomidine. Each has certain unique characteristics that make them an attractive choice for an AFOI.

A child with a difficult airway: what do I do next?

PURPOSE OF REVIEW

Difficulties in pediatric airway management are common and continue to result in significant morbidity and mortality. This review reports on current concepts in approaching a child with a difficult airway.

RECENT FINDINGS

Routine airway management in healthy children with normal airways is simple in experienced hands. Mask ventilation (oxygenation) is always possible and tracheal intubation normally simple. However, transient hypoxia is common in these children usually due to unexpected anatomical and functional airway problems or failure to ventilate during rapid sequence induction. Anatomical airway problems (upper airway collapse and adenoid hypertrophy) and functional airway problems (laryngospasm, bronchospasm, insufficient depth of anesthesia and muscle rigidity, gastric hyperinflation, and alveolar collapse) require urgent recognition and treatment algorithms due to insufficient oxygen reserves. Early muscle paralysis and epinephrine administration aids resolution of these functional airway obstructions. Children with an 'impaired' normal (foreign body, allergy, and inflammation) or an expected difficult (scars, tumors, and congenital) airway require careful planning and expertise. Training in the recognition and management of these different situations as well as a suitably equipped anesthesia workstation and trained personnel are essential.

SUMMARY

The healthy child with an unexpected airway problem requires clear strategies. The 'impaired' normal pediatric airway may be handled by anesthetists experienced with children, whereas the expected difficult pediatric airway requires dedicated pediatric anesthesia specialist care and should only be managed in specialized centers.