Airway Management

#### EXTRAGLOTTIC AIRWAYS

J Spec Oper Med. 2019 Fall;19(3):86-89.

# Survival of Casualties Undergoing Prehospital Supraglottic Airway Placement Versus Cricothyrotomy.

Schauer S, Naylor J, Chow A, Maddry J, Cunningham C, Blackburn M, Nawn C, April M

BACKGROUND: Airway compromise is the second leading cause of preventable death on the battlefield. Unlike a cricothyrotomy, supraglottic airway (SGA) placement does not require an incision and is less technically challenging. We compare survival of causalities undergoing cricothyrotomy versus SGA placement.

METHODS: We used a series of emergency department (ED) procedure codes to search within the Department of Defense Trauma Registry (DoDTR) from January 2007 to August 2016. This is a subanalysis of that dataset.

RESULTS: During the study period, 194 casualties had a documented cricothyrotomy and 22 had a documented SGA as the sole airway intervention. The two groups had similar proportions of explosive injuries (57.7% versus 63.6%, p = .328), similar composite injury severity scores (25 versus 27.5, p = .168), and similar AIS for the head, face, extremities, and external body regions. The cricothyrotomy group had lower AIS for the thorax (0 versus 3, p = .019) a trend toward lower AIS for the abdomen (0 versus 0, p = .077), more serious injuries to the head (67.5% versus 45.5%, p = .039), and similar rates of serious injuries to the face (4.6% versus 4.6%, p = .984). Glasgow Coma Scale (GCS) scores were similar upon arrival to the ED (3 versus 3, p = .467) as were the proportion of patients surviving to discharge (45.4% versus 40.9%, p = .691). On repeated multivariable analyses, the odds ratios (ORs) for survival were not significantly different between the two groups.

CONCLUSION: We found no difference in short-term outcomes between combat casualties who received an SGA vs cricothyrotomy. Military prehospital personnel rarely used either advanced airway intervention during the recent conflicts in Afghanistan and Iraq.

J Clin Anesth. 2019 Sep;56:134-135

# Airway management with a supraglottic airway for laparoscopic surgery: Does device selection matter?

King M, Jagannathan N

QUOTE:"To date, randomized studies have suggested that aspiration is no more common during procedures with an SGA when compared to an endotracheal tube. Due to the rarity of an aspiration event, however, designing a randomized study with enough power to determineequivalence of aspiration rates between SGAs and endotracheal tubes is prohibitively difficult. A definitive answer to this question will likely require the utilization of large data sets to determine rates of success and complications during laparoscopic and other procedures and, assuch, an analysis would require hundreds of thousands of patients in a multi-center effort. The advocacy of using second-generation SGAs for dynamic procedures such as laparoscopic surgery by airway specialty societies such as the Difficult Airway Society, Society for AirwayManagement, or European Airway Management Society may also encourage anesthesiologists to be more accepting of this practice, but further evidence would be needed to support an official endorsement.

In summary, Yoon and colleagues' analysis has provided greater insight for clinicians to select a specific type of SGA for laparoscopic procedures in order to optimize obtainable airway pressures needed to adequately ventilate the lungs. Their work joins a growing body ofliterature that increasingly supports the safe use of second-generation SGAs in suitable patients having laparoscopic surgery. While available randomized studies demonstrate low risks of aspiration when using an SGA for laparoscopy, the rarity of the event makes it difficult to fullycharacterize its use in this setting. In the future, the use of large data sets may provide adequate numbers of patients required to delineate the overall complication rates when using SGAs versus tracheal intubation."

Saudi J Anaesth. 2019 Jul-Sep;13(3):215-221

# Does prewarming of i-gel improve insertion and ventilation in anaesthetised and paralysed patients? A prospective, randomised, control trial.

Reddy A, Varghese N, Herekar B, Shenoy U

Context: I-gel are supraglottic airway devices with non-inflatable gel-like cuff that is believed to mould to body temperature, to seal the airway. Hence a pre-warmed i-gel may seal faster, provide better ventilation and superior leak pressure.

Aims: To determine if pre-warming i-gel to 40°C improves insertion and efficacy of ventilation.

Methods and Materials: A prospective, randomised, controlled trial was done on 64 patients requiring anaesthesia with muscle relaxation for short duration. For those in group W, i-gel warmed to 40°C for 15 minutes before insertion was used, whereas for those in group C, i-gel kept at room temperature (approximately 23°C) was used. The airway sealing pressure over time, number of attempts and time taken for a successful insertion were noted.

Statistical Analysis: Mean sealing pressure between two groups was compared using independent sample t-test. Repeated Measures ANOVA was used to analyse mean sealing pressure at 0, 15 and 30 min. P value ≤0.05 was considered statistically significant.

Results: Sealing pressure improves over time in both the groups but the mean sealing pressure was higher in group C when compared to group W at all points of time, however this was clinically and statistically insignificant. Ease of insertion, time for successful insertion, insertion attempts, intra-operative manoeuvres were all comparable between the groups with no adverse effects.

Conclusions: Pre-warming of i-gel to 40°C does not improve the success rate of insertion or provide a higher sealing pressure in anaesthetised and paralysed patients when compared to i-gel at room temperature.

Ther Clin Risk Manag. 2019 Mar 1;15:367-376

# Comprehensive evaluation of manikin-based airway training with second generation supraglottic airway devices.

Schmutz A, Bohn E, Spaeth J, Heinrich S

Background: Supraglottic airway devices (SADs) are an essential second line tool during difficult airway management after failed tracheal intubation. Particularly for such challenging situations the handling of an SAD requires sufficient training. We hypothesized that the feasibility of manikin-based airway management with second generation SADs depends on the type of manikin.

Methods: Two airway manikins (TruCorp AirSim® and Laerdal Resusci Anne® Airway Trainer™) were evaluated by 80 experienced anesthesia providers using 5 different second generation SADs (LMA® Supreme™ [LMA], Ambu® AuraGain™, i-gel®, KOO™-SGA and LTS-D™). The primary outcome of the study was feasibility of ventilation measured by assessment of the manikins' lung distention. As secondary outcome measures, oropharyngeal leakage pressure (OLP), ease of gastric tube insertion the insertion time, position and subjective assessments were evaluated.

Results: Ventilation was feasible with all combinations of SAD and manikin. By contrast, an OLP exceeding 10 cm H2O could be reached with most of the SADs in the TruCorp but with the LTS-D only in the Laerdal manikin. Gastric tube insertion was successful in above 90% in the Laerdal vs 87% in the TruCorp manikin (P<0.009). Insertion times differed significantly between manikins. The SAD positions were better in the Laerdal manikin for LMA, Ambu, i-gel and LTS-D. Participant's assessments were superior in the Laerdal manikin for LMA, Ambu, i-gel and KOO-SGA.

Conclusions: Ventilation is possible with all combinations. However, manikins are variable in their ability to adequately represent additional functions of second generation SADs. In order to achieve the best performance during training, the airway manikin should be chosen depending on the SAD in question.

Turk J Anaesthesiol Reanim. 2019 Feb;47(1):24-30

# Comparison between the Baska Mask® and I-Gel for Minor Surgical Procedures Under General Anaesthesia.

Sachidananda R, Shaikh S, Mitragotri M, Joshi V, Ladhad D, Mallappa M, Bhat V

Objective: Minor surgical procedures under general anaesthesia require a patent airway without the use of muscle relaxant. Supraglottic airway devices have been widely used for airway management. A study was undertaken to compare first-time insertion success rate, insertion time, sealing pressure and complications between the Baska® mask and I-gel.

Methods: After approval from the institutional ethical committee, a randomised single-blinded study was conducted on 50 American Society of Anesthesiologists' physical status I and II female patients aged 18-40 years who underwent minor surgical procedures under general anaesthesia. Patients were randomly categorized into two groups of 25 each; group Baska® mask and group I-gel, and the first-time success rate, mean insertion time and sealing pressure were measured. The results were analysed using unpaired t-test, Mann-Whitney U test, Chi square test and ANOVA. A p value <0.05 was considered to be statistically significant.

Results: The first-time insertion success rate of the Baska® mask was 21/24 (88%) when compared with the I-gel, which was 23/25 (92%) (p=0.585). The insertion time of the Baska® mask was 14.9±6.2 s, whereas that of the I-gel was 14.7±4.4 s (p=0.877). The mean sealing pressure of the Baska® mask was significantly higher when compared with the I-gel (28.9±3.5 vs. 25.9±2.5 cmH2O) (p=0.001).

Conclusion: The Baska® mask had a similar first-time insertion success rate and insertion time as the I-gel. The sealing pressure of the Baska® mask was significantly greater than that of the I-gel. Both devices had complications that were comparable.

J Clin Anesth. 2019 Oct 25:Epub ahead of print

# Predictors of early pharyngolaryngeal complications with cuffed supraglottic airway devices: A prospective observational study.

Thiruvenkatarajan V, Sim J, Emmerson R, Tong D, Liu W, Van Wijk R, Currie J

NO ABSTRACT AVAILABLE

Biomed Res Int. 2018 Nov 18;2018:5202957. doi: 10.1155/2018/5202957. eCollection 2018.

# A Comparison between the i-gel® and air-Q® Supraglottic Airway Devices Used for the Patients Undergoing General Anesthesia with Muscle Relaxation.

Massoudi N, Fathi M, Nooraei N, Salehi A

Objectives: The aim of the present study was to compare two supraglottic airway (SGA) devices (i.e., the i-gel® © Intersurgical Ltd and air-Q® (Reusable) Cookgas company) in terms of the insertion time, amount of leak during ventilation with maximum positive pressure, and postoperative complications in patients referring to Modarres Hospital in Tehran.

Method: The present double-blind clinical trial was performed on 60 patients undergoing elective surgeries that required general anesthesia with muscle relaxation. Patients were randomly assigned to either i-gel® (n = 30) or Air-Q® (n = 30) groups.

Results: The mean age, body mass index, duration of surgery, duration of anesthesia, and gender ratio were not significantly different between the two groups. Mean ± SD values of the SGA devices' insertion time (in seconds) in the air-Q® and i-gel® groups were 4.87 ± 1.6 and 6.80 ± 1.2, respectively (P < 0.001). The mean OLP in the Air-Q® group was significantly higher than that of the i-gel® group (35.9 ± 9.6 versus 24.8 ± 3.7, p < 0.001). The frequency of complications occurred after the supraglottic airway insertion was higher in the i-gel® group. However, only in terms of sore throat, the difference between the two groups was statistically significant: 6 (20%) had sore throat (P = 0.024) in the i-gel groups, but in in the Air-Q® groups no one had this side effect after surgery.

Conclusion: It was concluded that the Air-Q® supraglottic airway was placed faster and easier with fewer complications than the i-gel in general anesthesia with muscle relaxation. The frequency of the occurrence of all three complications, cough, sore throat, and blood, on the cuff (6 (20%) was higher in the i-gel group than that in the air-Q® group (cough3 (10%), sore throat 0 (0%), and blood on the cuff 3 (10%) (P < 0.05).

#### CRICOTHYROIDOTOMY

J Adv Med Educ Prof. 2019 Jul;7(3):144-148

# Comparison of the Bleeding Cricothyrotomy Model to SimMan for Training Students and Residents Emergency Cricothyrotomy.

Wray A, Khan F, Ray J, Rowe R, Boysen-Osborn M, Wiechmann W, Toohey S

Introduction: A cricothyroidotomy is an emergency procedure that few emergency medicine residents see or perform during their training. Therefore, there is a need for low cost, high fidelity models for training. In this study, we explore a new training model for cricothyroidotomies (the bleeding CRIC [cost-effective realistic interactive cricothyroidotomy]) to determine if this new task-trainer is non-inferior compared to the current standard of training.

Methods: Authors conducted a randomized control non-inferiority study. There were seventeen residents and medical students enrolled by convenience sample to partake in the study. The participants were randomized by block randomization to be taught how to perform a cricothyroidotomy on either the new task trainer or the current standard task trainer and then were asked to perform the procedure on a pig trachea model. Primary outcome measures were scores on a previously validated objective assessment tool and secondary outcomes were comfort levels and realism scores based on pre and post survey results which were analyzed with ANOVA.

Results: There was found to be no statistically significant difference between the groups in assessment scores, time to completion, or comfort levels pre- and post-intervention. There was a statistically significant difference in that the participants gave higher realism scores in post-test analysis to the Bleeding CRIC compared to the SimMan. Both groups demonstrated that they had significantly improved comfort levels from baseline post-intervention.

Conclusion: Overall, the new task trainer was rated by learners to feel more realistic than the current standard. This study demonstrates non-inferiority of the new task trainer and further studies with larger sample sizes should be conducted to determine its true efficacy.

A A Pract. 2018 Nov 12 [Epub ahead of print]

# A Case Report of an Inadvertent Placement of Tracheostomy Tube Into the Pharynx After Emergency Tracheostomy: Management of a Failed Surgical Airway.

Awad M, Yaghoubian S

Inadvertent placement of a tracheostomy tube through the stoma with the distal tip cephalad in the pharynx is an unusual but potentially devastating complication. Previously reported only once in the literature, its occurrence is not well known. There are several causes of ineffective ventilation after an emergency surgical airway, and an incorrectly placed tracheostomy tube is a differential diagnosis to consider. Prompt identification of this rare complication is essential because the consequences can be fatal. We present a case describing the inadvertent insertion of a tracheostomy tube into the pharynx during emergency tracheostomy and its subsequent management.

Laryngoscope Investig Otolaryngol. 2018 Oct 31;3(5):356-363

# Emergency front-of-neck airway by ENT surgeons and residents: A dutch national survey.

Bruijstens L, Titulaer I, Scheffer G, Steegers M, van den Hoogen F

Objectives: ENT surgeons and anesthesiologists work closely together in managing challenging airway cases. Sharing knowledge, experiences, and expectations interdisciplinary is essential in order to facilitate decision-making and adequate management in emergency front-of-neck airway cases.

Methods: A survey was performed, to analyze level of experience, technique of preference, training, knowledge of material and protocols, and self-efficacy scores of Dutch ENT surgeons and residents in performing an urgent or emergency front-of-neck airway.

Results: Within one year (January 2014-2015), 25.7% of the 257 respondents had performed an urgent or emergency front-of-neck airway. Of all reported emergency front-of-neck airways (N = 30), 80% were managed by tracheotomy. In future emergency front-of-neck airway cases, 74% stated cricothyrotomy would be their technique of preference. The majority would choose an uncuffed large-bore cannula technique. Post-academic hands-on training was attended by 42% of respondents. Self-efficacy scores were highest for surgical tracheotomy, and higher when trained or experienced. In case of an emergency scenario, 8.6% would not perform a front-of-neck airway themselves. The main reasons for reluctance to start in general were lack of experience and lack of training. Reported items for improvement were mainly the development of a protocol and training.

Conclusion: The chance of encountering an airway emergency scenario requiring front-of-neck airway is realistic. There is inconsistency between advised technique, technique of preference and technique actually performed by ENT surgeons. This study shows that there is both a need and desire for improvement in training and organization of care. Interdisciplinary guidelines and education is needed and could eventually safe lives.

Br J Anaesth. 2019 Feb;122(2):263-268

# Emergency cricothyroidotomy: an Observational study to estimate optimal incision position and length.

Fennessy P, Drew T, Husarova V, Duggan M, McCaul C

BACKGROUND: A vertical incision is recommended for cricothyroidotomy when the anatomy is impalpable, but no evidence-based guideline exists regarding optimum site or length. The Difficult Airway Society guidelines, which are based on expert opinion, recommend an 80-100 mm vertical caudad to cephalad incision in the extended neck position. However, the guidelines do not advise the incision commencement point. We sought to determine the minimum incision length and commencement point above the suprasternal notch required to ensure that the cricothyroid membrane would be accessible within its margins.

METHODS: We measured using ultrasound, in 80 subjects (40 males and 40 females) without airway pathology, the distance between the suprasternal notch and the cricothyroid membrane, in the neutral and extended neck positions. We assessed the inclusion of the cricothyroid membrane within theoretical incisions of 0-100 mm in length made at 10 mm intervals above the suprasternal notch.

RESULTS: In the 80 subjects, the distance ranged from 27 to 105 mm. Movement of the cricothyroid membrane on transition from the neutral to extended neck position varied from 15 mm caudad to 27 mm cephalad. The minimum incision required in the extended position was 70 mm in males and 80 mm in females, commencing 30 mm above the suprasternal notch.

CONCLUSIONS: An 80 mm incision commencing 30 mm above the suprasternal notch would include all cricothyroid membrane locations in the extended position in patients without airway pathology, which is in keeping with the Difficult Airway Society guidelines recommended incision length.

BMC Emerg Med. 2018 Nov 29;18(1):48

# Predictive value of quick surgical airway assessment for trauma (qSAT) score for identifying trauma patients requiring surgical airway in emergency room.

Hayashida K, Matsumoto S, Kitano M, Sasaki J

BACKGROUND: A surgical airway is usually unpredictable in trauma patients. The aim of this study was to develop a predictable scoring system to determine the need for a surgical airway by using a database from a large multicenter trauma registry.

METHODS: We obtained data from the nationwide trauma registry in Japan for adult blunt trauma patients who were intubated in the emergency department. Based on a multivariate logistic regression analysis in the development cohort, the Quick Surgical Airway Assessment for Trauma (qSAT) score was defined to predict the need for a surgical airway. The association of the qSAT with surgical airway was validated in the validation cohort.

RESULTS: Between 2004 and 2014, 17,036 trauma patients were eligible. In the development phase (n = 8129), the qSAT score was defined as the sum of the three binary components, including male sex, presence of a facial injury, and presence of a cervical area injury, for a total score ranging from 0 to 3. In the validation cohort (n = 8907), the proportion of patients with a surgical airway markedly increased with increasing qSAT score (0 points, 0.5%; 1 point, 0.9%; 2 points, 3.5%; 3 points, 25.0%; P <  0.001). Multivariate analysis revealed that qSAT score was an independent predictor of surgical airway (adjusted OR, 3.19 per 1 point increase; 95% CI, 2.47-4.12; P <  0.0001). The qSAT score of ≥1 had a had a good sensitivity of 86.8% for predicting the requirement for surgical airway; while qSAT score of 3 had a good specificity of 99.9% in ruling out the need for surgical airway.

CONCLUSIONS: The qSAT score could be assessed simply using only information present upon hospital arrival to identify patients who may need a surgical airway. The utilize of qSAT score in combination with repeated evaluations on physical finding could improve outcomes in trauma patients.

#### AIRWAY MANAGEMENT (GENERAL)

Ann Emerg Med. 2018 Dec;72(6):627-636

# Ultrasonography for the Confirmation of Endotracheal Tube Intubation: A Systematic Review and Meta-Analysis.

Gottlieb M, Holladay D, Peksa G

STUDY OBJECTIVE: Intubation is routinely performed in the emergency department, and rapid, accurate confirmation is essential to avoid potentially serious adverse outcomes. The number of studies assessing ultrasonography for the verification of endotracheal tube placement has expanded rapidly in recent years. We performed this systematic review and meta-analysis to determine the sensitivity and specificity of transtracheal ultrasonography for the verification of endotracheal tube location.

METHODS: PubMed, the Cumulative Index of Nursing and Allied Health, Scopus, Latin American and Caribbean Health Sciences Literature database, the Cochrane databases, and bibliographies of selected articles were assessed for all prospective and randomized controlled trials evaluating the accuracy of transtracheal ultrasonography for identifying endotracheal tube location. Data were dual extracted into a predefined worksheet and quality analysis was performed with the Quality Assessment of Diagnostic Accuracy Studies-2 tool. Data were summarized and a meta-analysis was performed with subgroup analyses by location, specialty, experience, transducer type, and technique. Time to confirmation was assessed as a secondary outcome.

RESULTS: This systematic review identified 17 studies (n=1,595 patients). Overall, transtracheal ultrasonography was 98.7% sensitive (95% confidence interval [CI] 97.8% to 99.2%) and 97.1% specific (95% CI 92.4% to 99.0%), with a positive likelihood ratio of 34.4 (95% CI 12.7 to 93.1) and a negative likelihood ratio of 0.01 (95% CI 0.01 to 0.02). Subgroup analyses did not demonstrate a significant difference by location, provider specialty, provider experience, transducer type, or technique. Mean time to confirmation was 13.0 seconds.

CONCLUSION: Transtracheal sonography is rapid to perform, with an acceptable degree of sensitivity and specificity for the confirmation of endotracheal intubation. Ultrasonography is a valuable adjunct and should be considered when quantitative capnography is unavailable or unreliable.

Emerg (Tehran). 2018;6(1):e58. Epub 2018 Oct 2.

# Evaluation of Airway Management Proficiency in Pre-Hospital Emergency Setting; a Simulation Study.

Ghiyasvandian S, Khazaei A, Zakerimoghadam M, Salimi R, Afshari A, Mogimbeigi A

Introduction: Infrequency and low exposure to critically ill patients requiring airway management will lead to reduction in the skills and performance of the Emergency Medical Technicians (EMTs) over time. The present study was conducted primarily aiming to evaluate airway management in stationary ambulance simulations and identify the factors affecting Endotracheal Intubation (ETI) success rate.

Method: This is a simulation study. The study population comprised of active EMTs in prehospital emergency bases in Hamadan province. The participants were placed at the back of an ambulance to perform the airway management scenario, which had already been prepared. To investigate the factors affecting the success (≤3 attempts) or failure rate of intubation, both unadjusted and adjusted odds ratios (95% confidence intervals) for univariate and multivariate regressions were reported.

Results: 184 subjects with the mean age of 33.91+6.25 years and the median work experience of 8 years were studied (54.3% with a history of training in the past year). The median number of previous intubations performed by technicians in the last year was 7 times (IQR 4-9). The total success rate at ventilation, intubation and back-up airway were 50.67%, 53.29%, and 50.0%, respectively. Out of the total 552 attempts for ETI placement, 58.2% of the technicians were able to perform ETI within 3 attempts. Univariate analysis showed that age (OR=1.06, P=0.022), previous number of ETIs (OR=2.49, P<0.001), work experience (OR=1.13, P<0.001), and previous ETI training (OR=1.85, P=0.041) were significantly associated with ETI success rate. After adjustment, previous number of ETIs (OR=2.66, P<0.001) was the most effective factor on ETI success rate.

Conclusion: Success rate in airway management, especially ETI, is low. Therefore, improvement in modifiable factors such as increasing the number of ETIs performed and gaining experience in the same conditions as pre-hospital emergency is necessary.

J Anaesthesiol Clin Pharmacol. 2018 Oct-Dec;34(4):490-495

# Assessment of awake i-gel™ insertion for fiberoptic-guided intubation in patients with predicted difficult airway: A prospective, observational study.

Ludeña J, Bellas J, Rementeria R, Muñoz Alameda L

Background and Aims: Orotracheal intubation (OTI) with fiberoptic bronchoscope (FOB) in spontaneous ventilation is one of the main techniques for patients with predicted difficult airway. Latest generation supraglottic airway devices have been designed to allow OTI through them. We assessed the safety and effectiveness of FOB-guided OTI through i-gel™ device which was inserted in spontaneously breathing patients with predicted difficult airway. Material and Methods: Eighty-five patients with difficult airway predictors were included. The i-gel was inserted under oropharyngeal local anaesthesia and sedation. After checking the adequate ventilation through the i-gel withcapnography curve, general anaesthesia was induced in order to introduce theendotracheal tube guided by FOB. We recorded the i-gel insertion time (t gel), intubation time (t int), O2 saturation in pulse oximetry (SpO2) at different times: basal (t 0), after 3 min of preoxygenation with a face mask at 100% FiO2 (t 1), after i-gel mask insertion (t 2) and after intubation (t 3). Adverse events during the procedure were also recorded.

Results: All patients were successfully intubated. SpO2 values were: 96.9 ± 1.2 (t 0), 99.0 ± 0.9 (t 1), 96.2 ± 2.4 (t 2), 96.0 ± 2.5 (t 3). t gel and t int were 38.0 ± 7.8 s and 36.5 ± 5.6 s, respectively. No serious adverse events were recorded and no patient suffered airway trauma.

Conclusion: I-gel insertion in spontaneous ventilation secures the airway before achieving fiberoptic intubation without the occurrence of adverse events. More studies might be necessary in order to confirm the results presented, but we consider that the technique described is a safe and effective alternative to classic OTI with FOB in spontaneously breathing patients with predicted difficult airway.

J Emerg Med. 2018 Nov;55(5):627-634

# Is Peripheral Oxygen Saturation a Reliable Predictor of Upper Airways Air-Flow Limitation?

Malagutti N, Di Laora A, Barbetta C, Groppo E, Tugnoli V, Sette E, Astolfi L, Beswick W, Borin M, Ciorba A, Pelucchi S, Stomeo F, Contoli M

BACKGROUND: Dyspnea secondary to acute upper airways airflow limitation (UAAFL) represents a clinical emergency that can be difficult to recognize without a suitable history; even when etiology is known, parameters to assess the severity are unclear and often improperly used.

OBJECTIVES: The aim of this study was to assess the role of peripheral oxygen saturation (SpO2) as a predictor of severity of upper airway obstruction.

METHODS: The authors propose an experimental model of upper airway obstruction by a progressive increase of UAAFL. Ten healthy volunteers randomly underwent ventilation for 6 min with different degrees of UAAFL. SpO2, heart rate, respiratory rate (RR), tidal volume, accessory respiratory muscle activation, and subjective dyspnea indexes were measured.

RESULTS: In this model, SpO2 was not reliable as the untimely gravity index of UAAFL. Respiratory rate, visual analogue scale (VAS), and Borg dyspnea scale were statistically correlated with UAAFL (p < 0.0001 for RR and p < 0.05 for VAS and Borg scale). No significant changes were observed on heart rate (p > 0.05) and tidal volume (p > 0.05); a RR ≤ 7 breaths/min; VAS and Borg scale showed statistically significant parameters changes (p < 0.05).

CONCLUSIONS: RR, VAS, and Borg dyspnea scales are sensitive parameters to detect and stage, easily and quickly, the gravity of an upper airways impairment, and should be used in emergency settings for an early diagnosis of a UAAFL. SpO2 is a poorer predictor of the degree of upper airways flow limitation.

Saudi J Anaesth. 2018 Oct-Dec;12(4):535-539

# Comparison of I-gel for general anesthesia in obese and nonobese patients.

Prabha R, Raman R, Khan M, Kaushal D, Siddiqui A, Abbas H

Context: I-gel is a second-generation supraglottic airway device. Despite several studies on i-gel, there are very few studies on the use of i-gel in obese patients.

Aims: The aim of the study was to compare the clinical performance of i-gel between obese and nonobese patients.

Settings and Design: Prospective, controlled, nonrandomized, hospital-based study.

Subjects and Methods: After obtaining informed consent, patients were divide into two groups of 16 patients each: group O consisted of patients with body mass index (BMI) >30 kg/m2 and Group C consisted of patients with BMI 18.5-29.9 kg/m2. I-gel was inserted after induction of anesthesia and muscle relaxation. Oropharyngeal leak pressure (OLP) (primary outcome variable), leak fraction, time taken to insert the device, ease of insertion, fiberoptic view of glottis through i-gel's airway tube, and adverse effects were recorded.

Statistical Analysis Used: Data were analyzed using SPSS 20. Continuous, ordinal, and categorical variables were analyzed using students t-test, Mann-Whitney U-test, and Fischer's exact test, respectively.

Results: OLP was slightly higher in Group O (25.38 ± 4.79 cm H2O) but was not statistically different than Group C (27.38 ± 4.38 cm H2O). Other parameters except weight and BMI (which were higher in Group O) were statistically similar in both groups. There was no statistical difference in side effects.

Conclusions: We concluded that i-gel is as effective in obese patients as in nonobese patients when used for securing the airway for surgical procedures.

BMC Emerg Med. 2019 Jan 23;19(1):12

# Prehospital cricothyrotomies in a helicopter emergency medical service: analysis of 19,382 dispatches.

Schober P, Biesheuvel T, de Leeuw M, Loer S, Schwarte L.

BACKGROUND: Creating a patent airway by cricothyrotomy is the ultimate maneuver to allow oxygenation (and ventilation) of the patient. Given the rarity of airway management catastrophes necessitating cricothyrotomy, sufficiently sized prospective randomized trials are difficult to perform. Our Helicopter Emergency Medical Service (HEMS) documents all cases electronically, allowing a retrospective analysis of a larger database for all cases of prehospital cricothyrotomy.

METHODS: We analyzed all 19,382 dispatches of our HEMS 'Lifeliner 1', since set-up of a searchable digital database. This HEMS operates 24/7, covering ~ 4.5 million inhabitants of The Netherlands. The potential cases were searched and cross-checked in two independent databases.

RESULTS: We recorded n = 18 cases of prehospital cricothyrotomy. In all 18 cases, less invasive airway techniques, e.g., supraglottic devices, were attempted before cricothyrotomy. With exception of 2 cases, at least one attempt of orotracheal intubation had been performed before cricothyrotomy. Out of the 18 cases, 4 were performed by puncture-based technique (Melker), the remaining 14 cases by surgical technique. Indications for cricothyrotomy were diverse, dividable into 9 trauma cases and 9 medical cases. The procedure was successful in all but one case (17/18, i.e., 94%; with a 95% confidence interval of 72.7-99.9%). Outcome was such that 6/18 patients arrived at the hospital alive. Long term outcome was poor, with only 2/18 patients discharged from hospital alive.

CONCLUSIONS: Cricothyrotomy remains, although rare, a regularly occurring requirement in (H)EMS. Our finding of a convincingly high success rate of 94% in trained hands encourages training and a timely performance of cricothyrotomy.

Eur J Anaesthesiol. 2019;Epub ahead of print

# Necessity to depict difficult neck anatomy for training of cricothyroidotomy: A pilot study evaluating two surgical devices on a new hybrid training model.

Hossfeld B, Mahler O, Mayer B, Kulla M, Helm M

BACKGROUND: Everyone dealing with airway emergencies must be able to accomplish cricothyroidotomy, which cannot be trained in real patients. Training models are necessary.

OBJECTIVE: To evaluate the suitability of a hybrid training model combining synthetic and porcine parts to depict variable neck anatomy.

DESIGN: Model-based comparative trial.

SETTING: Armed Forces Hospital Ulm, Germany, August 2018.

INTERVENTION: On four anatomical neck variations (long slim/long obese/short slim/short obese) we performed two surgical approaches to cricothyroidotomy (SurgiCric II vs. ControlCric).

PARTICIPANTS: Forty-eight volunteers divided into two groups based on their personal skill level: beginners group and proficient performers group.

MAIN OUTCOME MEASURES: Time to completion was recorded for each procedure. Once the operator had indicated completion, the correct anatomical tube placement was confirmed by dissection and structures were inspected for complications. Primary outcomes were successful tracheal placement of an airway tube and time needed to achieve a patent airway. Secondary outcome was assessment of complications.

RESULTS: Overall, 384 procedures were performed. Median time to completion was 74 s. In total, 284 procedures (74%) resulted in successful ventilation. Time to completion was longer in short obese than in long slim and the risk of unsuccessful procedures was increased in short obese compared with long slim. Even if ControlCric resulted in faster completion of the procedure, its use was less successful and had an increased risk of complications compared with SurgiCric II. Proficient performers group performed faster but had an increased risk of injuring the tracheal wall compared with beginners group.

CONCLUSION: Participants had difficulties in performing cricothyroidotomy in obese models, but various and difficult anatomical situations must be expected in airway management and therefore must be taught. A new hybrid model combining porcine and synthetic materials offers the necessary conditions for the next step in training of surgical airway procedures.

TRIAL REGISTRATION: The study was performed without human tissue or living animals, and was therefore exempted from ethical review by the University of Ulm Ethical Committee, Germany (Chairperson Prof Dr C. Lenk) on 9 August 2018. Hence a protocol number was not attributed.

Ulus Travma Acil Cerrahi Derg. 2018 Mar;24(2):97-103

# The success of endotracheal intubation with a modified laryngoscope using night vision goggles.

Aydın A, Bilge S, Aydın C, Bilge M, Çevik E, Eryılmaz M.

BACKGROUND: Endotracheal intubation (ETI) procedure in the combat area differs from prehospital trauma life support procedures because of the danger of gunfire and the dark environment. We aimed to determine the success, difficulty degree, and duration of ETI procedures with a classical laryngoscope (CL) in a bright room and with a modified laryngoscope (ML) model in a dark room.

METHODS: All interventions were performed by a combatant medical staff of 10 members. We developed an ML model to obtain a tool that can be used in combination with night vision goggles (NVGs) to perform ETI at night. The procedures were performed using a CL with the naked eye in a bright room and using a ML with NVGs in a dark room. The ETI procedure that used the ML was performed by engaging and locking the blade on the handle either in the mouth (ML-IM) or outside of the mouth (ML-OM).

RESULTS: The mean completion times for the ETI procedures, namely Day-CL, ML-OM+NVG, and ML-IM+NVG, performed by the operators were 14.46, 26.9, and 32.38 s, respectively. The ML-OM+NVG and ML-IM+NVG procedures were significantly longer than the Day-CL procedure (p<0.05). The ML-IM+NVG procedure was significantly longer than the ML-OM+NVG procedure (p<0.05). All ETI procedures were found to be 100% successful. The Day-CL procedure was easier than the ML-OM+NVG and ML-IM+NVG procedures (p>0.05).

CONCLUSION: The ETI procedure is applicable using NVGs in dark conditions on the battlefield. Medical interventions performed using NVGs in the dark should be a part of the basic training provided in tactical emergency medicine.

N Engl J Med. 2019 Jun 20;380(25):2482

# Bag-Mask Ventilation during Tracheal Intubation of Critically Ill Adults. Reply.

Casey J, Rice T, Semler M

BACKGROUND: Hypoxemia is the most common complication during tracheal intubation of critically ill adults and may increase the risk of cardiac arrest and death. Whether positivepressure ventilation with a bag-mask device (bag-mask ventilation) during trachealintubation of critically ill adults prevents hypoxemia without increasing the risk ofaspiration remains controversial.

METHODS: In a multicenter, randomized trial conducted in seven intensive care units in theUnited States, we randomly assigned adults undergoing tracheal intubation to receiveeither ventilation with a bag-mask device or no ventilation between induction andlaryngoscopy. The primary outcome was the lowest oxygen saturation observed duringthe interval between induction and 2 minutes after tracheal intubation. The secondaryoutcome was the incidence of severe hypoxemia, defined as an oxygen saturation ofless than 80%.

RESULTS: Among the 401 patients enrolled, the median lowest oxygen saturation was 96% (interquartile range, 87 to 99) in the bag-mask ventilation group and 93% (interquartilerange, 81 to 99) in the no-ventilation group (P = 0.01). A total of 21 patients (10.9%)in the bag-mask ventilation group had severe hypoxemia, as compared with 45 patients(22.8%) in the no-ventilation group (relative risk, 0.48; 95% confidence interval[CI], 0.30 to 0.77). Operator-reported aspiration occurred during 2.5% of intubationsin the bag-mask ventilation group and during 4.0% in the no-ventilation group(P = 0.41). The incidence of new opacity on chest radiography in the 48 hours aftertracheal intubation was 16.4% and 14.8%, respectively (P = 0.73).

CONCLUSIONS: Among critically ill adults undergoing tracheal intubation, patients receiving bag-mask ventilation had higher oxygen saturations and a lower incidence of severe hypoxemiathan those receiving no ventilation.

Anesthesiology. 2019 May;130(5):833-849

# Preparation for and Management of "Failed" Laryngoscopy and/or Intubation.

Cooper R

An airway manager's primary objective is to provide a path to oxygenation. This can be achieved by means of a facemask, a supraglottic airway, or a tracheal tube. If one method fails, an alternative approach may avert hypoxia. We cannot always predict the difficulties with each of the methods, but these difficulties may be overcome by an alternative technique. Each unsuccessful attempt to maintain oxygenation is time lost and may incrementally increase the risk of hypoxia, trauma, and airway obstruction necessitating a surgical airway. We should strive to optimize each effort. Differentiation between failed laryngoscopy and failed intubation is important because the solutions differ. Failed facemask ventilation may be easily managed with an supraglottic airway or alternatively tracheal intubation. When alveolar ventilation cannot be achieved by facemask, supraglottic airway, or tracheal intubation, every anesthesiologist should be prepared to perform an emergency surgical airway to avert disaster.

Ann Surg. 2019 Mar;269(3):e29-e30

# Prehospital Ground Transport Rapid Sequence Intubation for Trauma and Traumatic Brain Injury Outcomes.

Fitzgerald M, Lloyd-Donald P, Smit V, Mathew J, Kim Y, Tee J, Dewan Y, Mitra B

QUOTE:"We suggest that headlining the only positive, yet potentially flawed, finding of 4 secondary outcomes when the primary outcome has been refuted demands further assessment of prehospital RSI. Neurotrauma represents a significant personal, societal, and economic global health burden. It is clinically important to review any intervention as we attempt to reach an international consensus on the management of those with severe brain injury.

It is possible that a subgroup of patients, such as those transported by air or those with prolonged transport times, may benefit from prehospital RSI. However, it is equally possible that patients in urban areas, those in hemorrhagic shock and/or patients with surgically treatable brain injury may be harmed. Despite the extensively cited RCT, equipoise continues to exist and pending further trials, sound clinical judgment, which includes consideration of the benefits of early access to definitive care, should be applied before routine prehospital intubation after trauma."

#### BAG-VALVE-MASK (BVM)

J Spec Oper Med. 2019 Fall;19(3):71-75.

# A Comparison of the Laryngeal Handshake Method Versus the Traditional Index Finger Palpation Method in Identifying the Cricothyroid Membrane, When Performed by Combat Medic Trainees.

Moore A, Aden JK 3rd, Curtis R, Umar M.

BACKGROUND: The laryngeal handshake method (LHM) may be a reliable standardized method to quickly and accurately identify the cricothyroid membrane (CTM) when performing an emergency surgical airway (ESA). However, there is currently minimal available literature evaluating the method. Furthermore, no previous CTM localization studies have focused on success rates of military prehospital providers. This study was conducted with the goal of answering the question: Which method is superior, the LHM or the traditional method (TM), for identifying anatomical landmarks in a timely manner when performed by US Army combat medic trainees?

METHODS: This prospective randomized crossover study was conducted at Ft Sam Houston, TX, in September 2018. Two Army medic trainees with similar body habitus volunteered as subjects, and the upper and lower borders and midline of their CTMs were identified by ultrasound (US). The participants were also recruited from the medic trainee population. After receiving initial training on the LHM and refresher training on the TM, participants were asked to localize the CTMs of each subject with one method per subject. Success was defined as a marking within the borders and 5mm of midline within 2 minutes.

RESULTS: Thirty-two combat medic trainees participated; 78% (n = 25) successfully localized the CTM using the TM versus 41% (n = 13) using the LHM (p = .002).

CONCLUSION: Findings of this study support that at present the TM is a superior method for successful localization of the CTM when performed by Army combat medic trainees.

Crit Care Med. 2019 Mar;47(3):e222-e226

# Six Hours of Manual Ventilation With a Bag-Valve-Mask Device Is Feasible and Clinically Consistent.

Halpern P, Dang T, Epstein Y, Van Stijn-Bringas Dimitriades D, Koenig K

OBJECTIVES: Manual ventilation of intubated patients is a common intervention. It requires skill as well as physical effort and is typically restricted to brief periods. Prolonged manual ventilation may be unavoidable in some scenarios, for example, extreme mass casualty incidents. The present study tested whether nurses are capable of appropriately manually ventilating patients for 6 hours.

DESIGN: Volunteers performed ventilation on an electronic simulator for 6 hours while their own cardiorespiratory variables and the quality of the delivered ventilation were measured and recorded. The volunteers scored their perceived level of effort on a standard Borg Scale.

SETTING: Research laboratory at the Emergency Department, Tel Aviv Medical Center.

SUBJECTS: Ten nursing staff members of the Tel Aviv Sourasky Medical Center, 25-43 years old.

INTERVENTIONS: Volunteers ventilated manually a lung simulator for 6 hours.

MEASUREMENTS AND MAIN RESULTS: The subjects' physiologic states, including blood pressure, heart rate, respiratory rate, and oxygen saturation, showed no significant changes over time. The quality of delivered ventilation was somewhat variable, but it was stable on the average: average tidal volume ranged between 524.8 and 607.0 mL (p = 0.33). There was a slight but significant increase (7.3-10.9 L/min [p = 0.048]) in minute volume throughout the test period, reaching values consistent with mild hyperventilation. The subjects scored their perceived working effort as very light to fairly light, with a nonsignificant gradual increase in the Borg score as the study progressed.

CONCLUSIONS: Manual ventilation of intubated patients can be performed continuously for 6 hours without excessive physical effort on the part of the operator. The quality of delivered ventilation was clinically adequate for all of them. There was a mild but significant trend toward hyperventilation, albeit within safe clinical levels, which was due to an increasing ventilatory rate rather than an increase in tidal volume.

Wilderness Environ Med. 2019 Mar;30(1):52-55

# Success Rates with Digital Intubation: Comparing Unassisted, Stylet, and Gum-Elastic Bougie Techniques.

Juergens, Odom B, Ren C, Meyers K

INTRODUCTION: The utility of digital intubation, especially in an austere environment with limited equipment, has been previously described. However, evidence supporting best practices for its technique is limited. We seek to quantify the time to intubation and the rate of successful placement of the tube for digital intubation using different approaches and assistance devices.

METHODS: Using a manikin, digital intubation was performed with an endotracheal tube alone, with an endotracheal tube and a 14-French stylet, or with a gum-elastic bougie. All 3 techniques were performed in a crossover fashion at the manikin's side and head. Three trials per technique and position were performed. Outcomes measured were the time to intubation and the successful placement of the tube.

RESULTS: A total of 72 timed trials were performed. A significant difference did not exist between practitioners being positioned at the head vs side in terms of time or successful placement rate. There was no difference between the time to intubation in the tube-only and stylet-assisted groups, but the bougie-assisted group was significantly slower than the others. The stylet-assisted technique was significantly more successful than the other 2 techniques.

CONCLUSIONS: In a manikin model, stylet-assisted digital intubation was the most successful technique tested and allowed intubation to be accomplished just as quickly as with an endotracheal tube alone. Bougie-assisted digital intubation was slower and may not be as helpful as when it is used as an adjunct with direct laryngoscopy. Further research is needed to determine the utility of these adjuncts on live subjects.

Mil Med. 2019 Mar 1;184(Suppl 1):310-317

# Crossover Assessment of Intraoral and Cuffed Ventilation by Emergency Responders.

McCrory B, Lowndes B, Thompson D, Wadman M, Sztajnkrycer M, Walker R, Lomneth C, Hallbeck M

OBJECTIVES: A cuffed bag valve mask (BVM) is the most common device used by emergency medical responders to ventilate patients. The BVM can be difficult for users to seal around the patient's mouth and nose. An intraoral mask (IOM) with snorkel-like design may facilitate quicker and better ventilation particularly under austere conditions.

METHODS: Both a BVM and IOM were utilized by 27 trained emergency medical technicians and paramedics to ventilate a lightly embalmed cadaver. Ventilation efficacy, workload, and usability were assessed for both devices across four study conditions.

RESULTS: The IOM was superior to the BVM in delivered tidal volume ratio (measure of leak, p < 0.03) and minute ventilation (p < 0.0001). Workload, ergonomic and usability assessments indicated that the IOM facilitated gripping through the reduced hand interface size (p < 0.01), decreased user effort (p < 0.001), and reduced upper limb workload (p = 0.0088).

CONCLUSIONS: In the assessed model, the IOM represented a better choice for airway management than the standard cuffed BVM. An emergency medical device that is intuitive, efficacious and less demanding has the potential to reduce responder stress and improve resuscitation efforts, especially during austere rescue and patient transport.

Trauma Surg Acute Care Open. 2019 Feb 8;4(1):e000271

# Physician-based on-scene airway management in severely injured patients and in-hospital consequences: is the misplaced intubation an underestimated danger in trauma management?

Özkurtul O, Struck M, Fakler J, Bernhard M, Seinen S, Wrigge H, Josten C

Background: Endotracheal intubation (ETI) is the gold standard for the out-of-hospital emergency airway management in severely injured patients. Due to time-critical circumstances, poor patient presentation and hostile environments, it may be prone for mechanical complications and failure.

Methods: In a retrospective study (January 2011 to December 2013), all patients who underwent out-of-hospital ETI before admittance to a level 1 trauma center were analyzed consecutively. Patients with supraglottic airways, being under cardiopulmonary resuscitation and interfacility transports were excluded. The main study endpoint was the incidence of unrecognized tube malposition; secondary endpoints were Glasgow Outcome Scale (GOS) and in-hospital mortality adjusted to on-scene Glasgow Coma Scale (GCS), Injury Severity Score (ISS), Abbreviated Injury Scale head (AIS head), and on-scene time.

Results: Out of 1176 patients, 151 underwent out-of-hospital ETI. At hospital admission, tube malpositions were recognized in nine patients (5.9%). Accidental and unrecognized esophageal intubation was detected in five patients (3.3%) and bronchial intubation in four patients (2.7%). Although ISS (p=0.053), AIS head (p=0.469), on-scene GCS (p=0.151), on-scene time (p=0.530), GOS (p=0.748) and in-hospital mortality (p=0.431) were similar compared with correctly positioned ETI tubes, three esophageal intubation patients died due to hypoxemic complications.

Discussion: In our study sample, out-of-hospital emergency ETI in severely injured patients was associated with a considerable tube misplacement rate. For safety, increased compliance to consequently use available technologies (eg, capnography, video laryngoscopy) for emergency ETI should be warranted.

Level of evidence: Level of Evidence IIA.

PLoS One. 2019 Feb 27;14(2):e0212704

# Regurgitation and pulmonary aspiration during cardio-pulmonary resuscitation (CPR) with a laryngeal tube: A pilot crossover human cadaver study.

Ruetzler K, Leung S, Chmiela M, Rivas E, Szarpak L, Khanna S, Mao G, Drake R, Sessler D, Turan A

BACKGROUND: High-quality chest compressions are imperative for Cardio-Pulmonary-Resuscitation (CPR). International CPR guidelines advocate, that chest compressions should not be interrupted for ventilation once a patient's trachea is intubated or a supraglottic-airway-device positioned. Supraglottic-airway-devices offer limited protection against pulmonary aspiration. Simultaneous chest compressions and positive pressure ventilation both increase intrathoracic pressure and potentially enhances the risk of pulmonary aspiration. The hypothesis was, that regurgitation and pulmonary aspiration is more common during continuous versus interrupted chest compressions in human cadavers ventilated with a laryngeal tube airway.

METHODS: Twenty suitable cadavers were included, and were positioned supine, the stomach was emptied, 500 ml of methylene-blue-solution instilled and laryngeal tube inserted. Cadavers were randomly assigned to: 1) continuous chest compressions; or, 2) interrupted chest compressions for ventilation breaths. After 14 minutes of the initial designated CPR strategy, pulmonary aspiration was assessed with a flexible bronchoscope. The methylene-blue-solution was replaced by 500 ml barium-sulfate radiopaque suspension. 14 minutes of CPR with the second designated ventilation strategy was performed. Pulmonary aspiration was then assessed with a conventional chest X-ray.

RESULTS: Two cadavers were excluded for technical reasons, leaving 18 cadavers for statistical analysis. Pulmonary aspiration was observed in 9 (50%) cadavers with continuous chest compressions, and 7 (39%) with interrupted chest compressions (P = 0.75).

CONCLUSION: Our pilot study indicate, that incidence of pulmonary aspiration is generally high in patients undergoing CPR when a laryngeal tube is used for ventilation. Our study was not powered to identify potentially important differences in regurgitation or aspiration between ongoing vs. interrupted chest compression. Our results nonetheless suggest that interrupted chest compressions might better protect against pulmonary aspiration when a laryngeal tube is used for ventilation.

Clin Exp Emerg Med. 2019;Epub ahead of print

# Prehospital tracheotomy in a case of avulsion of the larynx with a comminuted fracture of the jawbone.

Rupprecht H, Gaab K

Emergency physicians in the field are sometimes confronted with cases wherein patients cannot be intubated and ventilated. In some cases, cricothyrotomy, the method of choice for securing an emergency airway, may not have a successful outcome. We report a rare case of a 35-yearold male patient with avulsion of the larynx and a comminuted fracture of the jawbone, due to entrapment in a dung excavator. Prehospital tracheotomy was successfully performed. In cases with crush injuries to the larynx, anatomic structures, including the ligamentum conicum, are destroyed. In addition, massive subcutaneous emphysema blurs the anatomical key structures; hence, only a tracheotomy can prevent a lethal outcome.

J Trauma Acute Care Surg. 2019 May;86(5):902-908

# Comparison of the efficacy of a bougie and stylet in patients with endotracheal intubation: A meta-analysis of randomized controlled trials.

Sheu Y, Yu S, Huang T, Liu F, Lin Y, Tam K

BACKGROUND: Endotracheal intubation (ETI) is a procedure widely performed for several clinical indications. In typical ETI, an endotracheal tube is placed into a patient's trachea with the help of a malleable metal rod covered with a clear plastic sheath (called a stylet). However, another intubation aid, a bougie (also named a gum elastic bougie or endotracheal tube introducer), was also introduced in the clinical setting to improve the efficacy of conventional ETI.

METHODS: This study performed a systematic review and meta-analysis of randomized controlled trials to compare the efficacy of bougie and stylet approaches in ETI. PubMed, Embase, and Cochrane Library databases were searched for studies published before November 2018. Randomized controlled trials comparing the clinical outcomes of bougie and stylet approaches in patients who underwent orotracheal intubation were included. Meta-analyses were conducted by using a random effects model, and treatment efficacy was measured by evaluating the first-attempt success rate and intubation duration.

RESULTS: A total of 5 randomized controlled trials and 1,038 patients were included. Although a bougie resulted in a better first-attempt success rate, no significant difference was observed between the approaches (risk ratios, 1.03; 95% confidence interval, 0.85-1.24). Moreover, no significant differences were observed in the intubation duration and esophageal intubation rate between the bougie and stylet approaches.

CONCLU SION: Endotracheal intubation performed with a bougie was not superior over ETI performed with a stylet. Therefore, intubation approaches should be selected by considering personal preference and clinician expertise.

LEVEL OF EVIDENCE: Systematic review and meta-analysis, level II.

Singapore Med J. 2019 Jun 14;Epub ahead of print

# Airway management in inhalation injury: a case series.

Desai S, Zeng D, Chong S

Inhalation injury is a serious consequence of a fire or an explosion, with potential airway compromise and respiratory complications. We present a case series of five patients with inhalational burns who presented to Singapore General Hospital and discuss our approach to their early management, including early evaluation and planning for the upper and lower airway, coexisting cutaneous burns, and monitoring their ICU (intensive care unit) severity of illness, sepsis and acute respiratory distress syndrome. All five patients suffered various grades of inhalation injury. The patients were initially assessed by nasolaryngoscopy, and three patients were prophylactically intubated before being sent to the emergency operating theatre for definitive airway and burns management with fibreoptic bronchoscopy. All patients were successfully extubated and discharged stable. Various complications can arise as a result of an inhalation injury. Based on our cases and literature review, we propose a standardised workflow for patients with inhalation injury.

Anaesthesia. 2019 Sep;74(9):1175-1185

# Difficult airway management algorithms: a directed review.

Edelman D, Perkins E, Brewster D

The primary aim of this study was to identify, describe and compare the content of existing difficult airway management algorithms. Secondly, we aimed to describe the literature reporting the implementation of these algorithms. A directed search across three databases (MEDLINE, Embase and Scopus) was performed. All articles were screened for relevance to the research aims and according to pre-determined exclusion criteria. We identified 38 published airway management algorithms. Our results show that most facemask employ a four-step process as represented by a flow chart, with progression from tracheal intubation, facemask ventilation and supraglottic airway device use, to a rescue emergency surgical airway. The identified algorithms are overwhelmingly similar, yet many use differing terminology. The frequency of algorithm publication has increased recently, yet adherence and implementation outcome data remain limited. Our results highlight the lack of a single algorithm that is universally endorsed, recognised and applicable to all difficult airway management situations.

Mil Med. 2019 Jul 9. pii: usz167. doi: 10.1093/milmed/usz167. [Epub ahead of

print]

# Definitive Management of a Traumatic Airway: Case Report.

Fabich R, Franklin B, Langan N

Maxillofacial and neck trauma from penetrating injuries present unique challenges for anesthesia providers and surgeons. In the austere conditions of a combat setting these challenges may be amplified due to limited resources and injury severity. Currently there is a lack of evidence and consensus on how to best manage a traumatized airway in this situation. The authors of this paper present the successful emergency management of a traumatized airway from a severe maxillofacial and neck-penetrating wound. A stepwise team approach using strong communication and a global mental model facilitated definitive airway management in this case allowing for safe transport to definitive care.

BMC Anesthesiol. 2019 Jul 9;19(1):124

# Ultrasonographic identification of the cricothyroid membrane in a patient with a difficult airway as a result of cervical hematoma caused by hemophilia: a case report.

Jimbo I, Uzawa K, Tokumine J, Mitsuda S, Watanabe K, Yorozu T

BACKGROUND: Surgical cricothyroidotomy is a last resort in patients with an anticipated difficult airway, but without any guarantee of success. Identification of the cricothyroid membrane may be the key to successful cricothyrotomy. Ultrasonographic identification of the cricothyroid membrane has been reported to be more useful than the conventional palpation technique. However, ultrasonographic identification techniques are not yet fully characterized.

CASE PRESENTATION: A 28-year-old man with hemophilia and poor adherence to medication. He was brought to the emergency department with a large cervical hematoma and respiratory difficulty. An otolaryngologist decided to insert a tracheal tube to maintain his airway. However, emergent laryngoscopy indicated an anticipated difficult airway. A backup plan that included awake intubation by the anesthesiologists and surgical cricothyroidotomy by an otolaryngologist was devised. The cricothyroid membrane could not be identified by palpation but was detected by ultrasonographic identification with a longitudinal approach. Awake fiberoptic intubation was successfully performed.

CONCLUSIONS: In this case, the cricothyroid membrane could be identified using the longitudinal approach but not the transverse approach. It may be ideal to know which ultrasound technique can be applied for each patient.

J Emerg Med. 2019 Sep;57(3):383-386

# Successful Intubation of a Difficult Airway Using a Yankauer Suction Catheter.

Patel K, Mastenbrook J, Pfeifer A, Bauler L

BACKGROUND: Endotracheal intubation (ETI) is used to effectively manage a patient's airway. Failure of ETI may lead to ineffective ventilation or oxygenation, potentially causing organ damage and eventually death. Approximately 8% of ETIs are difficult and 1% are unsuccessful. Tools and techniques to successfully obtain airway access are essential.

CASE REPORT: A patient with chronic obstructive pulmonary disease presented to the emergency department in acute respiratory distress. Noninvasive positive pressure ventilation was unsuccessful in improving the patient's tidal volume and work of breathing. The patient was unable to be intubated by conventional techniques because of a mass obstructing the view of her vocal cords. A cricothyrotomy was considered, but not initially performed because of her distorted anatomy. After multiple intubation attempts from several different physicians, the patient was successfully intubated with the aid of a suction Yankauer, which was used to move the mass peripherally and further served as a conduit through which a bougie was passed.

WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: The risk for complications rises with each intubation attempt. While there are a variety of tools and aids that can be used to assist in difficult intubations, rapid airway access is essential, and common tools do not always work. We hope that knowledge of this novel, yet simple and effective technique will help physicians successfully intubate patients with distorted oropharyngeal anatomy who cannot be intubated using conventional methods.

PLoS One. 2019 Jul 19;14(7):e0220006

# Comparison of video and conventional laryngoscopes for simulated difficult emergency tracheal intubations in the presence of liquids in the airway.

Suzuki K, Kusunoki S, Sadamori T, Tanabe Y, Itai J, Shime N

The presence of vomit, blood, or other foreign liquid materials in the upper airway is a major obstacle in difficult tracheal intubations (TIs) especially in prehospital care. However, the usefulness of video laryngoscopes (VLs) in these situations has not been investigated. The objective of this study was to compare the Airway Scope (AWS) and the Macintosh laryngoscope (ML) for their performance in TIs performed by emergency medical technicians (EMTs) using mannequin models with liquids in the airway. Rice gruel and mock blood were used to fill the upper airways of mannequins to create mock vomit and hematemesis models, respectively. TIs were performed by certified EMTs after visualizing the glottis using an AWS with an 18-Fr suction catheter and a ML with an 18-Fr suction catheter. TIs with AWS and ML were performed in random order in a comparative crossover trial. The TI success rate was evaluated based on the following: (a) the time taken from laryngoscope insertion into the oral cavity to glottis visualization, tracheal tube passage through the glottis, until the initiation of ventilation and (b) the subjective level of difficulty, which was assessed using a visual analog scale (VAS). TIs in vomiting and hematemesis scenarios were performed by 25 and 26 EMTs, respectively. The TI success rates for these scenarios were 100% with both AWS and ML. The median time required until successful ventilation was significantly shorter with AWS than with ML in both the vomiting (42 vs. 58 s) and hematemesis models (33 vs. 39 s), respectively. In the hematemesis scenarios, difficulty assessed using a VAS was lower with AWS than with ML (13 vs. 38 in median), respectively. Compared to the ML, the AWS was capable of faster and easier TIs, in a simulated model of liquid foreign material in the upper airway.

Laryngoscope. 2019 Sep 30;Epub ahead of print

# Live porcine model for surgical training in tracheostomy and open-airway surgery.

Deonarain A, Harrison R, Gordon K, Wolter N, Looi T, Estrada M, Propst E

OBJECTIVES/HYPOTHESIS: To evaluate the validity of a live porcine model for surgical training in tracheostomy and open-airway surgery.

STUDY DESIGN: Prospective observational study.

METHODS: Eleven expert otolaryngologists-head and neck surgeons rated a live porcine model's realism/anatomical accuracy (face validity) and perceived effectiveness as a training tool (content validity) for tracheostomy and laryngotracheoplasty using anterior costal cartilage and thyroid ala cartilage grafts using a 53-item post-trial questionnaire with a five-point Likert scale.

RESULTS: Experts rated the face validity of the live porcine model a median (interquartile range [IQR]) of 4/5 (4-5) and the content validity a median (IQR) of 5/5 (4-5) for each surgical procedure. Overall, 91% strongly agreed or agreed that the simulator would increase trainee competency for tracheostomy and laryngotracheoplasty using costal cartilage graft, and 82% strongly agreed or agreed that it would increase trainee competency for laryngotracheoplasty using thyroid ala cartilage graft.

CONCLUSIONS: The live porcine model has high face and content validity as a training tool for tracheostomy and laryngotracheoplasty using costal cartilage and thyroid ala cartilage grafts. This training model can help surgical trainees practice these complex, low-frequency procedures.

LEVEL OF EVIDENCE: NA Laryngoscope, 2019.

Air Med J. 2019 Sep - Oct;38(5):366-373

# Prehospital Airway Management in Severe Traumatic Brain Injury.

Gamberini L, Baldazzi M, Coniglio C, Gordini G, Bardi T

OBJECTIVE: Traumatic brain injury (TBI) is a leading cause of death and disability among trauma patients. The final outcome of TBI results from a complex interaction between primary and secondary mechanisms of injury that begin immediately after the traumatic event. The aim of this review was to evaluate the latest evidence regarding the impact of prehospital airway management and the outcome after traumatic brain injury.

METHODS: PubMed, Embase, and Cochrane searches were conducted using the MeSH database. Airway management, traumatic brain injury, pneumonia, and the subheadings of these Medical Subject Headings were combined.

RESULTS: The review is structured into 4 major topics: airway management devices, prehospital pharmacologic management, mortality and neurologic outcomes, and early respiratory infections. The available literature shows a shift toward a more comprehensive view of prehospital airway management, taking into account not only the location where airway management is attempted but also the drugs administered, the airway management devices used, and the skills of the main professional figures attending the scene.

CONCLUSIONS: Literature about this topic is still inconclusive; however, new evidence taking into consideration more complex aspects of airway management rather than orotracheal intubation per se shows improved outcomes with aggressive prehospital airway management.

Br J Anaesth. 2019 Nov;123(5):696-703

# Performance of emergency surgical front of neck airway access by head and neck surgeons, general surgeons, or anaesthetists: an in situ simulation study.

Groom P, Schofield L, Hettiarachchi N, Pickard S, Brown J, Sandars J, Morton B

BACKGROUND: The 'cannot intubate cannot oxygenate' (CICO) emergency requires urgent front of neck airway (FONA) access to prevent death. In cases reported to the 4th National Audit Project, the most successful FONA was a surgical technique, almost all of which were performed by surgeons. Subsequently, UK guidelines adopted surgical cricothyroidotomy as the preferred emergency surgical FONA technique. Despite regular skills-based training, anaesthetists may still be unwilling to perform an emergency surgical FONA. Consultant anaesthetists, head and neck surgeons, and general surgeons were compared in a high-fidelity simulated emergency. We hypothesised that head and neck surgeons would successfully execute emergency surgical FONA faster than anaesthetists and general surgeons.

METHODS: We recruited 15 consultants from each specialty (total of 45) at a single tertiary care hospital in the UK. All agreed to participate in an in situ high-fidelity simulation of an 'anaesthetic emergency'. Participants were not told in advance that this would be a CICO scenario.

RESULTS: There were no significant differences in total time to successful ventilation between anaesthetists, head and neck surgeons and general surgeons (median 86 vs 98 vs 126 s, respectively, P=0.078). Anaesthetists completed the emergency surgical FONA procedure significantly faster than general surgeons (median 50 vs 86 s, P=0.018). Despite this strong performance, qualitative data suggested some anaesthetists still believed 'surgeons' best placed to perform emergency surgical FONA in a genuine CICO situation.

CONCLUSION: Anaesthetists regularly trained in emergency surgical FONA function at levels comparable with head and neck surgeons and should feel empowered to lead this procedure in the event of a CICO emergency.

Crit Care Med. 2019 Oct;47(10):1362-1370

# Comparing the McGrath Mac Video Laryngoscope and Direct Laryngoscopy for Prehospital Emergency Intubation in Air Rescue Patients: A Multicenter, Randomized, Controlled Trial.

Kreutziger J, Hornung S, Harrer C, Urschl W, Doppler R, Voelckel W, Trimmel H

OBJECTIVES: Tracheal intubation in prehospital emergency care is challenging. The McGrath Mac Video Laryngoscope (Medtronic, Minneapolis, MN) has been proven to be a reliable alternative for in-hospital airway management. This trial compared the McGrath Mac Video Laryngoscope and direct laryngoscopy for the prehospital setting.

DESIGN: Multicenter, prospective, randomized, controlled equivalence trial.

SETTING: Oesterreichischer Automobil- und Touring Club (OEAMTC) Helicopter Emergency Medical Service in Austria, 18-month study period.

PATIENTS: Five-hundred fourteen adult emergency patients (≥ 18 yr old).

INTERVENTIONS: Helicopter Emergency Medical Service physicians followed the institutional algorithm, comprising a maximum of two tracheal intubation attempts with each device, followed by supraglottic, then surgical airway access in case of tracheal intubation failure. No restrictions were given for tracheal intubation indication.

MEASUREMENTS MAIN RESULTS: The Primary outcome was the rate of successful tracheal intubation; equivalence range was ± 6.5% of success rates. Secondary outcomes were the number of attempts to successful tracheal intubation, time to glottis passage and first end-tidal CO2 measurement, degree of glottis visualization, and number of problems. The success rate for the two devices was equivalent: direct laryngoscopy 98.5% (254/258), McGrath Mac Video Laryngoscope 98.1% (251/256) (difference, 0.4%; 99% CI, -2.58 to 3.39). There was no statistically significant difference with regard to tracheal intubation times, number of attempts or difficulty. The view to the glottis was significantly better, but the number of technical problems was increased with the McGrath Mac Video Laryngoscope. After a failed first tracheal intubation attempt, immediate switching of the device was significantly more successful than after the second attempt (90.5% vs 57.1%; p = 0.0003), regardless of the method.

CONCLUSIONS: Both devices are equivalently well suited for use in prehospital emergency tracheal intubation of adult patients. Switching the device following a failed first tracheal intubation attempt was more successful than a second attempt with the same device.

Can J Anaesth. 2019 Sep 23;Epub ahead of print

# Managing and securing the bleeding upper airway: a narrative review.

Kristensen M, McGuire B

Failure to manage bleeding in the airway is an important cause of airway-related death. The purpose of this narrative review is to identify techniques and strategies that can be employed when severe bleeding in the upper airway may render traditional airway management (e.g., facemask ventilation, intubation via direct/video laryngoscopy, flexible bronchoscopy) impossible because of impeded vision. An extensive literature search was conducted of bibliographic databases, guidelines, and textbooks using search terms related to airway management and bleeding. We identified techniques that establish a definitive airway, even in cases of impeded visibility resulting from severe bleeding in the airway. These include flexible video-/optical- scope-guided intubation via a supraglottic airway device; cricothyroidotomy or tracheotomy; and retrograde-, blind nasal-, oral-digital-, light-, and ultrasound-guided intubation. We provide a structured approach to managing bleeding in the airway that accounts for the source of bleeding and the estimated risk of failure to intubate using direct laryngoscopy or to achieve a front-of-neck access for surgical airway rescue. In situations where these techniques are predicted to be successful, the recommended approach is to identify the cricothyroid membrane (in preparation for rescue cricothyroidotomy), followed by rapid sequence induction. In situations where traditional management of the airway is likely to fail, we recommend an awake approach with one of the aforementioned techniques.

Medicine (Baltimore). 2019 Oct;98(42):e17713

# Incidence and outcomes of cricothyrotomy in the "cannot intubate, cannot oxygenate" situation.

Kwon Y, Lee C, Park S, Ha S, Sim Y, Baek M

Few data are available regarding factors that impact cricothyrotomy use and outcome in general hospital setting. The aim of the present study was to determine the incidence and outcomes of the patients underwent cricothyrotomy in a "cannot intubate, cannot oxygenate" (CICO) situation at university hospitals in Korea.This was a retrospective review of the electronic medical records of consecutive patients who underwent cricothyrotomy during a CICO situation between March, 2007, and October, 2018, at 2 university hospitals in Korea. Data regarding patient characteristics and outcomes were analyzed using descriptive statistics.During the study period, a total of 10,187 tracheal intubations were attempted and 23 patients received cricothyrotomy. Hospitalwide incidence of cricothyrotomy was 2.3 per 1000 tracheal intubations (0.23%). The majority of cricothyrotomy procedures (22 cases, 95.7%) were performed in the emergency department (ED); 1 cricothyrotomy was attempted in the endoscopy room. In the ED, 5663 intubations were attempted and the incidence of cricothyrotomy was 3.9 per 1000 tracheal intubations (0.39%). Survival rate at hospital discharge was 47.8% (11 of 23 cases). Except for cardiac arrest at admission, survival rate was 62.5% (10 of 16 cases). Successful cricothyrotomy was performed in 17 patients (73.9%) and 9 patients (52.9%) were survived. Among 6 patients of failed cricothyrotomy (26.1%), 2 patients (33.3%) were survived. After failure of cricothyrotomy, various methods of securing airway were established: 3 tracheal intubations, 1 nasotracheal intubation, and 1 tracheostomy.The success rate of cricothyrotomy and survival rate in the CICO situation were not high. After failure of cricothyrotomy, various methods of securing airway were performed.

Ann Emerg Med. 2018 Dec;72(6):645-653

# Emergency Department Intubation Success With Succinylcholine Versus Rocuronium: A National Emergency Airway Registry Study.

April M, Arana A, Pallin D, Schauer S, Fantegrossi A, Fernandez J, Maddry J, Summers S, Antonacci A, Brown C; NEAR Investigators.

STUDY OBJECTIVE: Although both succinylcholine and rocuronium are used to facilitate emergency department (ED) rapid sequence intubation, the difference in intubation success rate between them is unknown. We compare first-pass intubation success between ED rapid sequence intubation facilitated by succinylcholine versus rocuronium.

METHODS: We analyzed prospectively collected data from the National Emergency Airway Registry, a multicenter registry collecting data on all intubations performed in 22 EDs. We included intubations of patients older than 14 years who received succinylcholine or rocuronium during 2016. We compared the first-pass intubation success between patients receiving succinylcholine and those receiving rocuronium. We also compared the incidence of adverse events (cardiac arrest, dental trauma, direct airway injury, dysrhythmias, epistaxis, esophageal intubation, hypotension, hypoxia, iatrogenic bleeding, laryngoscope failure, laryngospasm, lip laceration, main-stem bronchus intubation, malignant hyperthermia, medication error, pharyngeal laceration, pneumothorax, endotracheal tube cuff failure, and vomiting). We conducted subgroup analyses stratified by paralytic weight-based dose.

RESULTS: There were 2,275 rapid sequence intubations facilitated by succinylcholine and 1,800 by rocuronium. Patients receiving succinylcholine were younger and more likely to undergo intubation with video laryngoscopy and by more experienced providers. First-pass intubation success rate was 87.0% with succinylcholine versus 87.5% with rocuronium (adjusted odds ratio 0.9; 95% confidence interval 0.6 to 1.3). The incidence of any adverse event was also comparable between these agents: 14.7% for succinylcholine versus 14.8% for rocuronium (adjusted odds ratio 1.1; 95% confidence interval 0.9 to 1.3). We observed similar results when they were stratified by paralytic weight-based dose.

CONCLUSION: In this large observational series, we did not detect an association between paralytic choice and first-pass rapid sequence intubation success or peri-intubation adverse events.

J Spec Oper Med. 2019 Fall;19(3):64-70.

# Airway Management for Army Reserve Combat Medics: An Interdisciplinary Workshop.

Miller BM, Kinder C, Smith-Steinert R.

BACKGROUND: An Army Reserve Combat Medic's training is focused on knowledge attainment, skill development, and building experience and training to prepare them to perform in austere conditions with limited resources like on the battlefield. Unfortunately, the exposure to skills they may be responsible for performing is limited. Research shows that greater than 90% of battlefield deaths occur in the prehospital setting, 24% of which are potentially survivable. Literature demonstrates that 91% of these deaths are related to hemorrhage; the remaining are related to other causes, including airway compromise. The skill and decision-making of this population are prime targets to optimize outcomes in the battlefield setting.

METHODS: Army Reserve combat medics were selected to voluntarily participate in an educational intervention provided by anesthesia providers focusing on airway management. Participants completed a preintervention assessment to evaluate baseline knowledge levels as well as comfort with airway skills. Medics then participated in a simulated difficult airway scenario. Next, airway management was reviewed, and navigation of the difficult airway algorithm was discussed. The presentation was followed by simulations at four hands-on stations, which focused on fundamental airway concepts such as bag-mask ventilation and placement of oral airways, tracheal intubation, placement of supraglottic airways, and cricothyrotomy. Pre/post knowledge assessments and performance evaluation tools were used to measure the effectiveness of the intervention.

RESULTS: Statistically significant results were found in self-reported confidence levels with airway skills (z = -2.803, p = .005), algorithm progression (z = -2.807, p = .005), and predicting difficulty with airway interventions based on the patient's features (z = -2.809, p = .005). Establishment of ventilation was completed faster after the intervention. More coherent and effective airway management was noted, new knowledge was gained, and implications from psychological research applied.

CONCLUSION: Supplementing the training of Army Reserve Combat Medics with the utilization of anesthesia providers is an effective platform. This exercise imparted confidence in this population of military providers. This is critical for decision-making capabilities, performance, and the prevention of potentially survivable mortality on the battlefield.