Ultrasound identification of the cricothyroid membrane: the new standard in preparing for front-of-neck airway access

[Ultrasound supported identification of the ligamentum conicum in teaching head and neck sonography]

OBJECTIVE

Upper airway obstructions are usually acute emergencies. Coniotomy is the last option to secure the airway and can be supported by sonography. The aim of this study was to establish a training program to teach these skills.

MATERIAL AND METHODS

The training consisted of theoretical training with an additional video presentation (10 minutes each) and practical training (45 minutes). Evaluations were completed before (T1) and after (T2) the training to measure prior experience and satisfaction with the training as well as subjective and objective competence levels. At T2, a practical test was also completed by n=113 participants. A standardized evaluation form was used to document the results of the practical test.

RESULTS

A large proportion of the participants had neither seen a coniotomy (64.6%) nor performed one independently (79.6%). Significant improvement (T1 to T2) was measured with regard to the subjective assessment of competence (p<0.001). The training received positive ratings for all items tested (scale ranges 1-2). During practical tests, the participants achieved an average of 89.2% of the possible points and needed a mean of 101 ±23 seconds to identify the conic ligament.

CONCLUSION

Structured training for sonographic identification of the conic ligament leads to significant improvement in the subjective assessment of competence and a high objective competence level in a short period of time. This type of training should be standardized in head and neck ultrasound training in the future.

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.

Point-of-care ultrasound for airway management in the emergency and critical care setting

Airway management is a common procedure within emergency and critical care medicine. Traditional techniques for predicting and managing a difficult airway each have important limitations. As the field has evolved, point-of-care ultrasound has been increasingly utilized for this application. Several measures can be used to sonographically predict a difficult airway, including skin to epiglottis, hyomental distance, and tongue thickness. Ultrasound can also be used to confirm endotracheal tube intubation and assess endotracheal tube depth. Ultrasound is superior to the landmark-based approach for locating the cricothyroid membrane, particularly in patients with difficult anatomy. Finally, we provide an algorithm for using ultrasound to manage the crashing patient on mechanical ventilation. After reading this article, readers will have an enhanced understanding of the role of ultrasound in airway management.

Expedited awake tracheal intubation using ropivacaine topicalisation for the evacuation of a postoperative neck haematoma in the presence of lignocaine allergy

Progressive airway compromise from a neck haematoma is a feared complication of head and neck surgery that can rapidly lead to death if not urgently intervened upon. We report a case of a patient developing a progressively expanding neck haematoma on the first postoperative night after parotidectomy and neck dissection for malignancy. Although he did not have respiratory compromise or stridor, ultrasound examination of his airway revealed marked tracheal deviation, and flexible nasoendoscopy showed significant supraglottic swelling. The decision was made for an awake fibreoptic intubation; however, a complicating factor was a history of lignocaine allergy. This case report describes the unconventional use of atomised ropivacaine in a concentration of 0.5% for topicalisation of the airway. Along with conscious sedation with remifentanil, ropivacaine provided excellent conditions for awake intubation, following which a significant amount of blood was evacuated from the face and neck.

Anatomical morphometry for Cricothyrotomy puncture and incision

PURPOSE

Emergency surgical airway securing techniques include cricothyrotomy, puncture, and incision. While the instruments used for these methods vary in size, no index of laryngeal morphology exists to guide instrument selection. Therefore, we measured the morphology of the cricothyroid ligament in Japanese individuals and assessed its correlations with height.

METHODS

This retrospective study used 61 anatomical practice specimens. The cricothyroid ligament of the laryngeal area was dissected, and a frontal image was recorded. Next, images of the midsagittal sections of the larynx and trachea were recorded. The width and height of the cricothyroid ligament were measured from the frontal images, and the depth of the larynx and the angle to the lower edge of the cricothyroid plate were measured from the mid-sagittal cross-sectional images. The height was estimated from the tibial lengths of the specimens and statistically analyzed for correlations. 　 RESULTS: The width and depth were significantly greater in males. Overall, there was a slight correlation between the results of each laryngeal measurement and estimated height for all items.

CONCLUSION

The morphology of cricothyrotomy revealed that the width and depth of the laryngeal area varied according to sex. Moreover, the results also showed a correlation with the estimated height. Thus, it is important to predict the morphology of the laryngeal area and cricothyroid ligament by considering factors such as patient sex, weight, and height.

Infrared flashing light through the cricothyroid membrane as guidance to awake intubation with a flexible bronchoscope: A randomised cross-over study

BACKGROUND

In case of distorted airway anatomy, awake intubation with a flexible bronchoscope can be extremely difficult or even impossible. To facilitate this demanding procedure, an infrared flashing light source can be placed on the patient's neck superficial to the cricothyroid membrane. The light travels through the skin and tissue to the trachea, from where it can be registered by the advancing bronchoscope in the pharynx and seen as flashing white light on the monitor. We hypothesised that the application of this technique would allow more proximal and easier identification of the correct pathway to the trachea in patients with severe airway pathology.

METHODS

As part of awake intubation, patients underwent insertion of a flexible video bronchoscope via the mouth into the trachea. The procedure was performed twice, in random order in each patient, with and without the aid of the transcutaneous flashing infrared light. All insertions were video recorded to determine at which anatomical landmark within the airway the correct pathway was identified. The videos are accessible via this link: https://airwaymanagement.dk/infrared_comparative. The predefined landmarks were in successive order: oral cavity, oro-pharynx, tip of epiglottis, arytenoid cartilages, false cords, vocal cords and trachea, as well as the spaces between them.

RESULTS

Twenty-two patients had a total of 44 awake insertions with the flexible bronchoscope. The median anatomical level, at which correct identification of the trachea was obtained on the monitor, was, past the epiglottis, with the conventional technique, and at the level of the oropharynx, when using the infrared flashing light (p = .005). The time until the flashing light or the vocal cords were seen was 21 (22) S, mean (SD), and 48 (62) S, during the insertion with and without infrared flashing light activated, respectively (p = .005). Endoscopists rated it easier (p = .001) to recognise the entrance to the trachea in the infrared-group.

CONCLUSION

During awake intubation of patients with airway pathology, the application of trans-cricothyroid infrared flashing light to guide the insertion of a flexible bronchoscope significantly facilitated the recognition of the pathway into the trachea and the correct advancement of the flexible endoscope.

REGISTRATION OF CLINICAL TRIAL

NCT03930550.

Airway ultrasound for patients anticipated to have a difficult airway: Perspective for personalized medicine

Airway ultrasound allows for precise airway evaluation, particularly for assessing the difficult airway and the potential for front of neck access. Many studies have shown that identification of the cricothyroid membrane by airway ultrasound is more accurate than digital palpation. However, no reports to date have provided clinical evidence that ultrasound identification of the cricothyroid membrane increases the success rate of cricothyroidotomy. This is a narrative review which describes patients with difficult airways for whom airway ultrasound may have been useful for clinical decision making. The role of airway ultrasound for the evaluation of difficult airways is summarized and an approach to the use of ultrasound for airway management is proposed. The goal of this review is to present practical applications of airway ultrasound for patients predicted to have a difficult airway and who undergo cricothyroidotomy.

Role of ultrasonography in an impalpable tissue larynx model during a simulated front-of-neck access scenario: a randomized simulation study

PURPOSE

A large vertical incision is recommended when performing front-of-neck access in patients with impalpable neck landmarks during a cannot intubate-cannot oxygenate (CICO) scenario. We investigated the impact of ultrasonography on vertical incision size of a front-of-neck access on an ultrasound-compatible impalpable porcine larynx model.

METHODS

Emergency medicine and anesthesia trainees were randomized to the Ultrasound (US, n = 21) and Non-Ultrasound (NUS, n = 21) groups. Within 1 week after a teaching session on airway ultrasound and Scalpel-Bougie-Tube (SBT) technique, participants were instructed to perform cricothyroidotomy on the model during a simulated cannot intubate-cannot oxygenate scenario. The primary outcome was a vertical size incision. Secondary outcomes were procedural completion time, horizontal size incision, tissue injury severity, and correct tube placement.

RESULTS

The ultrasound group performed a significantly smaller vertical incision [median (IQR), 35.0 (15, 40) vs 65.0 (52, 100) mm (95% CI) - 30.0 (- 55.1, - 4.9), p = 0.02] and took longer total time to complete the procedure [median (IQR), 200.5 (126, 267) vs 93.5 (71.0, 167.5) secs (95% CI) 91.0 (3.73, 178.3), p = 0.04]. Tissue injury severity and correct tube placement were similar between groups.

CONCLUSIONS

Ultrasound-guided identification of the cricothyroid membrane significantly reduced the recommended vertical incision size with similar success rates. However, there was an increased time when performing a Scalpel-Bougie-Tube cricothyroidotomy on an impalpable porcine larynx model by physicians in training. Ultrasonography should not be used in an emergency scenario of airway rescue. Its potential use to pre-mark the cricothyroid membrane should be considered in difficult airway management of impalpable neck.

Airway Ultrasound for Anesthesia and in Intensive Care Patients-A Narrative Review of the Literature

Ultrasound is an everyday diagnostic tool. In anesthesia and intensive care, it has a role as an adjuvant for many procedures, including the evaluation of the airway. Ultrasound airway evaluation can help predict a difficult airway, visualize the proper positioning of an intubation cannula, or evaluate the airway post-intubation. Protocols need to be established for the better integration of ultrasound in the airway evaluation, however until a consensus is reached in this respect, the ultrasound is a reliable aid in anesthesia and intensive care.

Evaluation of a novel emergency front of neck access device in a benchtop model of obesity

BACKGROUND

Emergency front of neck access (eFONA) is a critical step in oxygenation in cases of unrelieved airway obstruction. Multiple techniques are used in clinical practice without agreement regarding the optimal approach. We evaluated a novel device, the Cric-Guide (CG), a channelled bougie introducer that enters the airway in a single action and compared it with a scalpel-bougie-tube (SBT) technique in laboratory benchtop model.

METHODS

Seven anaesthesiologists attempted eFONA on both obese and non-obese models using both techniques in randomized order on an excised porcine trachea with an intact larynx with variable subcutaneous tissue depth. The primary outcome was successful tracheal cannulation. Secondary outcomes included false passage rate, time and tissue injury.

RESULTS

Anaesthesiologists performed 4 cricothyroidotomies on each model with each device. The CG was more successful in airway cannulation (47/56 [89.4%] vs. 33/56 [58.9%], P = 0.007). This difference was observed in the obese model only. The CG was associated with fewer false passages than the standard technique in the obese model (8/56 [14.3%] vs. 23/56 [41.1%], P = 0.006). There were no significant differences in time to completion or injury patterns between the techniques in the obese model, but the SBT was faster in the non-obese model. There was no difference in the proportion of specimens injured.

CONCLUSION

The Cric-Guide device was more successful than the standard SBT technique in airway cannulation in an obese neck model and with equivalent frequency and distribution of injury but performed equivalently in the non-obese model.

203 Ultrasound Identification of the Cricothyroid Membrane for Emergency Front of Neck Access

The difficult airway society states that emergency front of neck access skills should be recapped every 6 months amongst those practitioners expected to perform the skill. Furthermore, the national audit states that, of the 25 emergency cricothyroidotomy cases, 9 failed. These were largely due to incorrect identification of the midline and tube misplacement. There is a convincing argument for training practitioners in ultrasound identification of the cricothyroid membrane, mitigating the risks of incorrect midline identification and blood vessel damage

Our aim was two-fold: introduce and embed the skill of ultrasound identification of the cricothyroid membrane for use in emergency front of neck access and encourage regular recap of these skills through a training package of blended learning, consisting of videos, ‘tea trolley’ style theatre training and a more formal simulation-based course that focuses on the ultrasound and front of neck access skill and human factors as we know this is a key factor in the success or failure of this scenario.

A pilot course was rolled out amongst anaesthetic trainees to assess relative comfort with performing emergency front of neck access. The course consisted of a short lecture on the background and anatomy, teaching of the ultrasound skill using live subjects, practising of ultrasound-guided front of neck access on animal necks and finally a simulation with debrief surrounding implementation of the skill itself and human factors. This course is now being rolled out regionally and aims to teach all trainees in the region. We encourage trainees to generate their own informal logbook of ultrasound cases, whereby they consent patients to undergo a short ultrasound scan in the anaesthetic room prior to intubation, have their neck marked and then are rescanned after intubation to confirm correct identification. This should be done with ‘normal’ airways, not just those expected to be difficult, as this practice embeds the skill. Our ‘tea trolley’ style teaching is yet to be commenced but will involve ad hoc teaching within the theatre suite including the multi-disciplinary team who would be involved in such an event – the anaesthetist, operating department practitioner and theatre team. Finally, we are generating a video bank, which can be accessed in users’ own time to recap and review the process and troubleshooting of ultrasound identification of the cricothyroid membrane and ensuing cricothyroidotomy.

An improvement was reported in trainees’ comfort levels to perform ultrasound-guided cricothyroidotomy and all trainees felt that this was a worthwhile skill to embed into their practice. These improvements were tested via a pre- and post-course questionnaire. The same we hope will be true for the tea trolley training and we aim to address the human factors involved during these sessions too.

The aspiration is that ultimately ultrasound identification of the cricothyroid membrane for emergency front of neck access will at the very least become a skill that all trainees are formally taught and encouraged to practice and at the most will become the new standard for plan D airway access in the difficult airway society guidelines.

Comparison of the Conventional Downward and Modified Upward Laryngeal Handshake Techniques to Identify the Cricothyroid Membrane: A Randomized, Comparative Study

BACKGROUND

Accurate identification of the cricothyroid membrane is crucial for successful cricothyroidotomy. The aim of this study was to compare the conventional downward and modified upward laryngeal handshake techniques in terms of accuracy to identify the cricothyroid membrane in nonobese female patients.

METHODS

In 198 anesthetized female patients, the cricothyroid membrane was identified by either the conventional downward laryngeal handshake technique (n = 99) or the modified upward laryngeal handshake technique (n = 99). According to the conventional downward laryngeal handshake technique, the cricothyroid membrane was identified by palpating the neck downward from the greater cornu of the hyoid bone, thyroid laminae, and cricoid cartilage. According to the modified upward laryngeal handshake technique, the cricothyroid membrane was located by moving up from the sternal notch. The primary outcome was the accuracy of identifying the cricothyroid membrane. Secondary outcomes included the accuracy of midline identification and time taken to locate what participants believed to be the cricothyroid membrane. The primary and secondary outcomes according to the technique were analyzed using generalized estimating equations.

RESULTS

The cricothyroid membrane could be identified more accurately by the modified upward laryngeal handshake technique than by the conventional downward technique (84% vs 56%, respectively; odds ratio [OR], 4.36; 95% confidence interval [CI], 2.13-8.93; P < .001). Identification of the midline was also more accurate by the modified laryngeal handshake than by the conventional technique (96% vs 83%, respectively; OR, 4.98; 95% CI, 1.65-15.01; P = .004). The time taken to identify the cricothyroid membrane was not different between the conventional and modified techniques (20.2 [16.2-26.6] seconds vs 19.0 [14.5-26.4] seconds, respectively; P = .83).

CONCLUSIONS

The modified upward laryngeal handshake technique that involved tracing the trachea and laryngeal structures upward from the sternal notch was more accurate in identifying the cricothyroid membrane than the conventional downward technique in anesthetized female patients.

Managing Known Difficult Airways in Obstetric Patients Using a Flexible Bronchoscope and IRRIS: A Case-Illustrated Guide for Nonexpert Anesthesiologists, without Surgical Backup

Pregnancy is associated with anatomical and physiological changes leading to potential difficult airway management. Some pregnant women have known difficult airways and cannot be intubated even with a hyperangulated videolaryngoscope. If neuraxial techniques are also impossible, awake tracheal intubation with a flexible bronchoscope may be one of the few available options to avoid more invasive techniques. The Infrared Red Intubation System (IRRIS) may help nonexpert anesthesiologists in such situations and may enhance the chance of successful intubation increasing safety for the mother and the fetus, especially in hospitals without the ear, nose, and throat surgical backup.

Anatomical and positional variants of the brachiocephalic trunk in a Mexican population

Background

Brachiocephalic trunk (BCT) variants may have a clinical impact during surgical procedures, some of which could be fatal. The objective of this study was to classify height positions of the BCT and report their prevalence in a Mexican population.

Methods

Patients: A retrospective, descriptive, observational, and cross-sectional was performed using computed tomography angiography (CTA) of adult (> 18 years of age) patients, without gender distinction, of Mexican origin. Measuring techniques were standardized using the suprasternal notch to analyze linear and maximum heights, linear and curved lengths, and the vertebral origin and bifurcation levels of the BCT.

Results

A total of 270 CTA were obtained (66.7% men and 33.3% women). A high position of BCT was present in 64.81% (n 175/270). The mean linear medial height was 0.58 ± 1.91 cm, the maximum height of the free edge was 3.85 ± 2.04 cm, side length of the midline at the maximum height of the free edge was 1.46 ± 2.59, linear length 3.72 ± 0.70, and a curve length 3.99 ± 0.79. The BCT origin was most predominant at the T3 (57.9%) and T4 (27.0%) vertebral levels, with the bifurcation at T2 (57.9%) and T1 (36.2%).

Conclusions

There is a high prevalence of high position BCT in our population. Patients should be assessed before any procedures in the area, due to the potential risk of complications.

Infrared flashing light through the cricothyroid membrane to guide flexible bronchoscopic tracheal intubation

Flexible bronchoscopic tracheal intubation is a fundamental technique in the management of the difficult airway but requires specific skills which may be both difficult to achieve and maintain. Therefore, techniques to improve its success should be developed. We present two cases, one where the ear, nose and throat surgeon could not view the glottis due to laryngeal pathology, and one where pathology in the oropharynx obscured access to the trachea during attempts at flexible bronchoscopic and videolaryngoscopic tracheal intubation. In both cases, tracheal intubation was subsequently successful due to the use of the Infrared Red Intubation System. This is an infrared light source that is secured to the anterior neck. It emits a flashing infrared light that is captured by the flexible bronchoscope, thus guiding the way to the trachea. These are the first reports of this technology being used for flexible bronchoscopic tracheal intubation in patients with severe airway pathology where conventional approaches had failed. Both cases emphasise that this technique can be of benefit in avoiding a surgical airway.

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.