Airway Management

#### AIRWAY MANAGEMENT (GENERAL)

Ann Emerg Med. 2018 May 7. pii: S0196-0644(18)30318-4

# 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 M, 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 Trauma Acute Care Surg. 2018 Jul;85(1S Suppl 2):S154-S160

# Prehospital airway procedures performed in trauma patients by ground forces in Afghanistan.

Blackburn M, April M, Brown D, DeLorenzo R, Ryan K, Blackburn A, Schauer S.

BACKGROUND: Airway management is of critical importance in combat trauma patients. Airway compromise is the second leading cause of potentially survivable death on the battlefield and accounts for approximately 1 in 10 preventable deaths. Reports from the Iraq and Afghanistan wars indicate 4% to 7% incidence of airway interventions on casualties transported to combat hospitals. The goal of this study was to describe airway management in the prehospital combat setting and document airway devices used on the battlefield.

METHODS: This study is a retrospective review of casualties that required a prehospital lifesaving airway intervention during combat operations in Afghanistan. We obtained data from the Prehospital Trauma Registry that was linked to the Department of Defense Trauma Registry for outcome data for the time period between January 2013 and September 2014.

RESULTS: Seven hundred five total trauma patients were included, 16.9% required a prehospital airway management procedure. There were 132 total airway procedures performed, including 83 (63.4%) endotracheal intubations and 26 (19.8%) nasopharyngeal airway placements. Combat medics were involved in 48 (36.4%) of airway cases and medical officers in 73 (55.3%). Most (94.2%) patients underwent airway procedures due to battle injuries caused by explosion or gunshot wounds. Casualties requiring airway management were more severely injured and less likely to survive as indicated by Injury Severity Score, responsiveness level, Glascow Coma Scale, and outcome.

CONCLUSION: Percentages of airway interventions more than tripled from previous reports from the wars in Afghanistan and Iraq. These changes are significant, and further study is needed to determine the causes. Casualties requiring airway interventions sustained more severe injuries and experienced lower survival than patients who did not undergo an airway procedure, findings suggested in previous reports.

Emerg Med Australas. 2018 May 11. doi: 10.1111/1742-6723.13107. [Epub ahead of print]

Influence of prehospital airway management on neurological outcomes in patients transferred to a heart attack centre following out-of-hospital cardiac arrest.

Edwards T, Williams J, Cottee M

OBJECTIVE: To describe the association between prehospital airway management and neurological outcomes in patients transferred by the ambulance service directly to a heart attack centre (HAC) post-return of spontaneous circulation (ROSC).

METHODS: A retrospective observational cohort study in which ambulance records were reviewed to determine prehospital airway management strategy and collect physiological and demographic data. HAC notes were obtained to determine in-hospital management and quantify neurological outcome via the cerebral performance category (CPC) scale. Statistical analyses were performed via χ2 -test, Mann-Whitney U-test, odds ratios and binomial logistic regression.

RESULTS: Two hundred and twenty patients were included between August 2013 and August 2014, with complete outcome data obtained for 209. Median age of patients with complete outcome data was 67 years and 71.3% were male (n = 149). Airway management was provided using a supraglottic airway (SGA) in 72.7% of cases (n = 152) with the remainder undergoing endotracheal intubation (ETI). There was no significant difference in the proportion of patients who had a good neurological outcome (CPC 1 and 2) at discharge between the SGA and ETI groups (P = 0.29). Binomial logistic regression incorporating factors known to influence outcome demonstrated no significant difference in neurological outcomes between the SGA and ETI groups (adjusted OR 0.73, 95% CI 0.34-1.56).

CONCLUSION: In this observational study, there was no significant difference in the proportion of good neurological outcomes in patients managed with SGA versus ETI during cardiac arrest and in the post-ROSC transfer phase. Further research is required to provide more definitive evidence in relation to the optimal airway management strategy in out-of-hospital cardiac arrest.

Emerg Med Australas. 2018 Jun 11. doi: 10.1111/1742-6723.13114. [Epub ahead of print]

# Ketamine use for rapid sequence intubation in Australian and New Zealand emergency departments from 2010 to 2015: A registry study.

Ferguson I, Alkhouri H, Fogg T, Aneman A

OBJECTIVE: This study aimed to quantify the proportion of patients undergoing rapid sequence intubation using ketamine in Australian and New Zealand EDs between 2010 and 2015.

METHODS: The Australian and New Zealand Emergency Department Airway Registry is a multicentre airway registry prospectively capturing data from 43 sites. Data on demographics and physiology, the attending staff and indication for intubation were recorded. The primary outcome was the annual percentage of patients intubated with ketamine. A logistic regression analysis was conducted to evaluate the factors associated with ketamine use.

RESULTS: A total of 4658 patients met inclusion criteria. The annual incidence of ketamine use increased from 5% to 28% over the study period (P < 0.0001). In the logistic regression analysis, the presence of an emergency physician as a team leader was the strongest predictor of ketamine use (odds ratio [OR] 1.83, 95% confidence interval [CI] 1.44-2.34). The OR for an increase in one point on the Glasgow Coma Scale was 1.10 (95% CI 1.07-1.12), whereas an increase of 1 mmHg of systolic blood pressure had an OR of 0.98 (95% CI 0.98-0.99). Intubation occurring in a major referral hospital had an OR of 0.68 (95% CI 0.56-0.82), while trauma conferred an OR of 1.38 (95% CI 1.25-1.53).

CONCLUSIONS: Ketamine use increased between 2010 and 2015. Lower systolic blood pressure, the presence of an emergency medicine team leader, trauma and a higher Glasgow Coma Scale were associated with increased odds of ketamine use. Intubation occurring in a major referral centre was associated with lower odds of ketamine use.

Mil Med. 2018 Jun 19. doi: 10.1093/milmed/usy144. [Epub ahead of print]

# Non-conventional utilization of the Aintree intubation catheter to facilitate exchange between three supraglottic airways and an endotracheal tube: a cadaveric trial.

Lopez N, McCoy S, Carroll C, Jones E, Miller J

Background: Two studies by Bledsoe et al and Anand et al reported limited efficacy of the Supraglottic Airway Laryngeal Tube (SALT), which is a supraglottic airway (SGA) specifically designed for blind endotracheal intubation. Miller et al reported a 50% success rate using an Eschmann introducer as an adjunct for blind airway exchange via the laryngeal mask airway (LMA) classic. Another study by Ueki et al found that endotracheal tube (ETT) intubation was faster and less damaging to the airway when the Aintree intubating catheter was used in conjunction with a fiberoptic bronchoscope. To date there are no studies utilizing the King laryngeal tube (LT) for blind airway exchange were found.

Methods: This was a prospective crossover study. Participants were recruited from a group of active duty emergency department medical personnel participating in a cadaver training lab. Researchers pre-placed SGA devices in six cadavers with grade I/II airways. Participants attempted airway exchange with each SGA for 2 minutes. The order of SGA devices was alternated for each successive participant. Participants rated the ease or difficulty of placement for each SGA. Success of airway exchange was defined as proper placement of the ETT in the trachea and was confirmed by the same emergency medicine physician via direct laryngoscopy throughout the entire study.

Results: Forty-four emergency department personnel participated in the study. Pairwise McNemar's tests revealed a significantly higher success rate for the LMA unique (LMAU) compared with the King LT (p = 0.039) and a significantly higher success rate for the i-gel compared to both the LMAU (p = 0.007) and the King LT (p < 0.001). Pairwise McNemar's tests also indicated that failure due to placement errors was significantly less prevalent and failure due to running over time was significantly more prevalent with the King LT compared to the i-gel (p = 0.004) and the LMAU (p = 0.002). There was no significant relationship between blind airway exchange success rates and prior intubation experience.

Conclusion: Considering success rate, ease of use and price, the i-gel was found superior to the King LT and the LMAU for blind airway exchange with an ETT when using an Aintree intubating catheter as an introducer.

J Emerg Med. 2018 Jul;55(1):e15-e18

# Iatrogenic tracheal rupture caused by emergency intubation: a case report.

Schaeffer C, Galas T, Teruzzi B, Sudrial J, Allou N, Martinet O

BACKGROUND: Iatrogenic tracheal rupture is a rare but life-threatening complication. If suspected by clinical examination or chest radiograph, a computed tomography scan can confirm the diagnosis, but the criterion standard is a bronchoscopy. There is no consensus on its management.

CASE REPORT: A 52-year-old woman was intubated in a prehospital setting after cardiac arrest. A gradual appearance of subcutaneous emphysema was observed after intubation. A computed tomography scan revealed a complicated tracheal rupture, pneumomediastinum, and pneumothorax. The management was surgical. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: Intubation in emergency conditions increases the risk of tracheal rupture and a delay in management is an important prognostic factor.

#### EXTRAGLOTTIC AIRWAYS

Indian J Anaesth. 2018 May;62(5):350-358

# Direct and indirect low skill fibre-optic intubation: A randomised crossover manikin study of six supraglottic airway devices.

Chow S, Tan Y, Wong T, Ho V, Matthews A, Li H, Wong P

Background and Aims: Fibre-optic intubation (FOI) through supraglottic airway devices (SADs) is useful in the management of the difficult airway. We compared two methods of FOI through seven SADs in a randomised crossover manikin study to assess each device's performance and discuss implications on SAD selection.

Methods: Thirty anaesthetsiologists, 15 seniors and 15 juniors, each performed low skill FOI (LSFOI) with seven SADs using both 'direct' and 'indirect' methods. The order of method and device used were randomised. The primary end point was success rate of intubation; secondary end points were time taken for intubation, incidence of difficulties with direct and indirect LSFOI and operator device preference. Statistical analysis was with univariable analysis and comparison of proportions.

Results: Data from six devices were analysed due to a protocol breach with one SAD. There was no difference in intubation success rate across all SADs and intubation methods. Intubation time was significantly shorter in AmbuAuragain than other SADs and shorter with the direct method of LSFOI than the indirect method (mean difference of 6.9 s, P = 0.027). Ambu Auragain had the least SAD and bronchoscope-related difficulties. Seniors had significantly shorter mean intubation times than juniors by 11.6 s (P = 0.0392). The most preferred SAD for both methods was AmbuAuragain.

Conclusion: Low skill FOI consistently achieves a high intubation success rate regardless of experience, choice of method, or SAD used. SAD design features may significantly affect the performance of low skill FOI.

Anaesthesia. 2018 Jul;73(7):856-862

# Changes in hardness and resilience of i-gel™ cuffs with temperature: a benchtop study.

Dingley J, Stephenson J, Allender V, Dawson S, Williams D

The i-gelTM is a supraglottic airway with a gel-like thermoplastic cuff. It has been suggested that the seal around the larynx improves following insertion. Perhaps the most intuitive hypothesis proposed for this is that cuff softening occurs during warming from ambient to body temperature. We investigated this using a food industry texture analyser over a wide temperature range. Size 2 and 3 i-gels were secured to a platform within a temperature-controlled water bath, which was in turn mounted on a texture analyser test stand. Both water and i-gel cuff temperatures were recorded. A spherical probe was advanced 4 mm into the surface of each i-gel at a rate of 1 mm.s-1 , then retracted at the same rate while the upward pressure on the probe was recorded. Three runs made at each of the 11 temperatures (10 °C to 60 °C, 5 °C increments) gave 105,864 data points, from which values for hardness (the peak force on the probe at maximum indentation), and resilience (the rate at which the material recovers its original shape) were calculated. Over 10 to 60 °C, the smallest hardness value expressed as a proportion of the largest was 88.2% and 89.8% for size 2 and 3 i-gels, respectively, and for resilience these were 92.8% and 86.2%, respectively. Over room temperature to body temperature range (21-37.4 °C), hardness decreased by 3.15% and increased by 0.47% for i-gel sizes 2 and 3, respectively, whereas resilience values decreased by 1.85% and 2.68%, respectively. Cuff hardness and resilience did generally reduce with warming, but the effect was minimal over temperature ranges that may be encountered during clinical use.

J Anesth. 2018 Jul 18. doi: 10.1007/s00540-018-2531-7. [Epub ahead of print]

# Superior sealing effect of a three-dimensional printed modified supraglottic airway compared with the i-gel in a three-demensional printed airway model.

Kimijima T, Edanaga M, Yamakage M

PURPOSE: The aim of this study was to compare the force exerted by a three-dimensional (3D) printed modified supraglottic airway (mSGA) vs. that exerted by the i-gel on a 3D printed airway model.

METHODS: After a preliminary experiment in Thiel embalmed cadavers, we created a 3D printed mSGA and five 3D printed airway models based on computed tomography data from five female Japanese patients. We compared the force exerted by the i-gel and mSGA on the larynx of the 3D printed airway models. In addition, tidal volumes with insertion of the airway devices into the 3D printed airway model and administration of different levels of pressure-controlled ventilation (PCV) were compared.

RESULTS: The values below indicate mean values ± SD (p value, 95% confidence interval) for the mSGA and i-gel, respectively. The forces exerted by the cuff parts were as follows: ventral: 12.5 ± 5.4 vs. 20.7 ± 3.7 N (p = 0.0001, - 10.0 to - 6.5), proximal: 1.9 ± 1.4 vs. 1.7 ± 1.3 N (p = 0.322, - 0.26 to 0.74), and dorsal parts: 6.9 ± 2.2 vs. 12.5 ± 4.8 N (p = 0.0001, - 7.9 to - 3.4), respectively. We also found significantly higher tidal volumes with the mSGA under PCV of 10, 15, and 20 cmH2O.

CONCLUSIONS: The method of creating the mSGA that we proposed in this study can be applied to development of novel SGAs that is anatomically more suitable for pharyngolaryngeal structure.

Rom J Anaesth Intensive Care. 2018 Apr;25(1):7-9. doi:10.21454/rjaic.7518.251.sor.

# Spring recoil and supraglottic airway devices: lessons from the law of conservation of energy.

Sorbello M, Zdravkovic I, Cataldo R, Di Giacinto I

In the Oxford dictionary, recoil is rebound or spring back through force of impact or elasticity, and this term is widely used with particular reference to automatic weapons. In this specific setting, the recoil spring is used to compensate and absorb the bullet force momentum and to convert energy into the activation of a weapon’s reloading system. Based on the principle of energy conservation, this is an example of how we could use for a different (and useful) purpose a simple physical phenomenon.

In this issue of the Romanian Journal of Anaesthesia and Intensive Care, Corda and co-workers present an interesting paper based on the same conceptual principle: using the physical recoil of a laryngeal mask pilot balloon valve to adjust the mask’s intracuff pressure and keep it within safety levels.

#### CRICOTHYROIDOTOMY

Thorac Surg Clin. 2018 Aug;28(3):435-440

# Cricothyroid approach for emergency access to the airway.

Bribriesco A, Patterson G.

Airway emergencies are life-threatening events that face providers of many different backgrounds. In cannot-intubate-cannot-ventilate situations, emergent access to the airway can be obtained through the cricothyroid membrane by cricothyroidotomy. The 3 main techniques are open, percutaneous, and needle cricothyroidotomy. To date, there is no compelling evidence demonstrating superiority of a particular approach. Ultimately, the method used for cricothyroidotomy should be based on the comfort and experience of the provider performing the procedure.

Korean J Anesthesiol. 2018 Aug;71(4):289-295. doi: 10.4097/kja.d.18.00025. Epub 2018 May 30.

# A bench study comparing between scalpel-bougie technique and cannula-to-Melker technique in emergency cricothyroidotomy in a porcine model.

Chang S, Tong Q, Beh Z, Quek K, Ang B

BACKGROUND: The ideal emergency cricothyroidotomy technique remains a topic of ongoing debate. This study aimed to compare the cannula-to-Melker technique with the scalpel-bougie technique and determine whether yearly training in cricothyroidotomy techniques is sufficient for skill retention.

METHODS: We conducted an observational crossover bench study to compare the cannula-to-Melker with the scalpel-bougie technique in a porcine tracheal model. Twenty-eight anesthetists participated. The primary outcome was time taken for device insertion. Secondary outcomes were first-pass success rate, incidence of tracheal trauma, and technique preference. We also compared the data on outcome measures with the data obtained in a similar workshop a year ago.

RESULTS: The scalpel-bougie technique was significantly faster than the cannula-to-Melker technique for cricothyroidotomy (median time of 45.2 s vs. 101.3 s; P = 0.001). Both techniques had 100% success rate within two attempts; there were no significant differences in the first-pass success rates and incidence of tracheal wall trauma (P &gt; 0.999 and P = 0.727, respectively) between them. The relative risks of inflicting tracheal wall trauma after a failed cricothyroidotomy attempt were 6.9 (95% CI 1.5-31.1), 2.3 (95% CI 0.3-20.7) and 3.0 (95% CI 0.3-25.9) for the scalpel-bougie, cannula-cricothyroidotomy, and Melker-Seldinger airway, respectively. The insertion time and incidence of tracheal wall trauma were lower when the present data were compared with data from a similar workshop conducted the previous year.

CONCLUSIONS: This study supports the use of a scalpel-bougie technique for cricothyroidotomy by anesthetists and advocates a yearly training program for skill retention.

Acta Anaesthesiol Scand. 2018 Oct;62(9):1223-1228

# Utility of the laryngeal handshake method for identifying the cricothyroid membrane.

Oh H, Yoon S, Seo M, Oh E, Yoon H, Lee H, Lee J, Ryu H

BACKGROUND: The cricothyroid membrane is the most commonly accessed location for invasive surgical airway. Although the laryngeal handshake method is recommended for identifying the cricothyroid membrane, there is no clinical data regarding the utility of the laryngeal handshake method in cricothyroid membrane identification. The objective of this study was to compare the accuracy of cricothyroid membrane identification between the laryngeal handshake method and simple palpation.

METHODS: After anaesthesia induction, the otorhinolaryngology resident and anaesthesia resident identified and marked the needle insertion point for cricothyroidotomy using simple palpation and the laryngeal handshake method, respectively. The cricothyroid membrane was confirmed with ultrasonography. Identification was determined successful if the marked point was placed within the longitudinal area of the cricothyroid membrane and within 5 mm from midline transversely. The accuracy of cricothyroid membrane identification using the laryngeal handshake method and simple palpation was compared.

RESULTS: A total of 123 patients were enrolled. The cricothyroid membrane was correctly identified in 87 (70.7%, 95% confidence interval 61.8-78.6%) patients using the laryngeal handshake method compared to 78 (63.4%, 95% confidence interval 54.3-71.9%) patients using simple palpation (P = .188). The time required to identify the cricothyroid membrane was longer when using the laryngeal handshake method (15 [3-48] seconds vs 10.9 [3-55] seconds, P = .003).

CONCLUSION: The success rate of identifying the cricothyroid membrane was similar among the anesthesiologists who performed the laryngeal handshake method and also among otorhinolaryngologists who used simple palpation.

Anaesthesia. 2018 Oct;73(10):1235-1243

# Evaluation of a novel criocthyroidotomy introducer in a simulated obese porcine model: a radomised crossover comparison with scalpel cricothyroidotomy.

Yeow C, Greaney L, Foy C, King W, Patel B

The Difficult Airway Society 2015 guidelines for management of unanticipated difficulties in tracheal intubation in adults have generated much discussion regarding Plan D: emergency front-of-neck access with a scalpel-bougie cricothyroidotomy technique. There is concern that this technique may not provide an adequate pathway for the bougie and subsequently the tracheal tube, especially in obese patients with deeper airway structures. This could lead to the formation of a false passage, trauma and failure. A novel cricothyroidotomy introducer, 8 mm wide and 170 mm long, with a sharp leading edge and guiding channel to pass a bougie into the trachea, has been designed to complement the scalpel cricothyroidotomy technique. A comparison study of the use of this novel introducer with the scalpel technique in a simulated obese porcine laryngeal model demonstrated shorter insertion times (median (IQR [range]) 85 (65-123 [48-224]) s vs. 84 (72-184 [46-377]) s, p = 0.030). All 26 (100%) participants successfully performed cricothyroidotomy in the introducer group, whereas only 24 (92%) participants were successful in the scalpel group. The introducer group required fewer attempts to access the trachea compared with the scalpel group (p = 0.046). False passages occurred eight (31%) times in the introducer group compared with 17 (65%) times in the scalpel group (p = 0.022). There were no statistical differences in tracheal trauma (p = 0.490), ease of use (p = 0.220) and device preference (p = 0.240). This novel cricothyroidotomy introducer has shown promising results in securing the airway in an emergency front-of-neck access situation. With robust training, this introducer could potentially be complementary to the scalpel-bougie cricothyroidotomy technique.