A radiographic comparison of human airway anatomy and airway manikins – Implications for manikin-based testing of artificial airways

Comparison of bougie-guided cricothyrotomy and traditional cricothyrotomy techniques in an obese 3D-printed surgical airway manikin: a randomized controlled study

BACKGROUND

Obesity is one of the conditions that may require invasive airway management. The effectiveness of invasive airway techniques in obesity is not fully understood, and there is no routinely recommended technique. This study aimed to compare the first attempt success rate, procedure time, and difficulty of traditional surgical cricothyrotomy and bougie-guided cricothyrotomy on a 3D-printed surgical airway manikin made obese using simple techniques.

METHODS

The study was designed as a prospective randomized controlled study. The obese simulation was created with a 3D-printed surgical airway manikin and sponge layers. Bougie-guided cricothyrotomy and traditional cricothyrotomy techniques were taught to emergency residents, and they were asked to practice the technique on the designed manikin. The duration of the procedure for both techniques, the number of attempts, the success rate, and the difficulty scores of the techniques were recorded.

RESULTS

A total of 24 residents were included in the study. As the first technique, 13 residents used bougie-guided cricothyrotomy. A total of 23 (95.8%) were successful with both techniques. In the traditional surgical cricothyrotomy, 7 (31.8%) residents were successful on the first attempt, while in the bougie-guided cricothyrotomy, 15 (68.2%) residents were successful on the first attempt (p = 0.020). In residents with less than 2 years of seniority, the mean difficulty score of the bougie-guided cricothyrotomy was lower (p = 0.024).

CONCLUSIONS

The success rate of the bougie-guided cricothyrotomy in the first attempt was higher than that of the traditional surgical technique. There was no statistically significant difference between the overall success rates and procedure times of both methods. The level of difficulty of the bougie-guided cricothyrotomy was found to be easier, especially for residents with less than two years of seniority.

PRESENTATIONS

The manuscript has been presented 9th EurAsian Congress on Emergency Medicine (oral presentation) at the 9-12 November, 2023, Antalya, Turkey, and won the best oral abstract award at this congress.

Simulation based education in paediatric resuscitation

There is increasing use of clinical Simulation Based Education (SBE) in healthcare due to an increased focus on patient safety, the call for a new training model not based solely on apprenticeship, a desire for standardised educational opportunities that are available on-demand, and a need to practice and hone skills in a controlled environment. SBE programs should be evaluated against Kirkpatrick level 3 or 4 criteria to ensure they improve patient or staff outcomes in the real world. SBE programs have been shown to improve outcomes in neonatology - reductions in hypoxic ischaemic encephalopathy, in brachial plexus injury, rates of school age cerebral palsy, reductions in 24hr mortality and improvements in first pass intubation rates. In paediatrics SBE programs have shown improvements in paediatric cardiac arrest survival, PICU survival, reduced PICU admissions, reduced PICU length of stay and reduced time to critical operations. SBE can improve the non-technical tasks of teamwork, leadership and communication (within the team and with patients and carers). Simulation is a useful tool in Quality and Safety and is used to identify latent safety issues that can be addressed by future programs. In high stakes assessment simulation can be a mode of assessment, however, care needs to be taken to ensure the tool is validated carefully.

Evaluating the Usability of a 3D-Printed Video Laryngoscope for Tracheal Intubation of a Manikin

Background

Compared to direct laryngoscopy, videolaryngoscopy (VL) can provide improved laryngeal and glottic view, higher intubation success rates in patients with a known or predicted difficult airway and reduced incidence of laryngeal/airway trauma. However, the cost and availability of these devices handicap its use in resource-restricted facilities. The objective was to design and manufacture a novel VL using additive manufacturing (AM) and evaluate its usability on an intubation manikin by comparing it to one of the most common video laryngoscopes used in clinical practice, the CMAC^®, by measuring the time to first pass of the endotracheal tube as the main outcome.

Methods

A randomised cross-over study was performed with 36 anaesthetists attempting tracheal intubation of a manikin. The novel 3D-printed hyperangulated VL blade was compared to a CMAC^® VL (D-blade). Participants had no prior experience or training with the novel device. The participants included consultants, registrars/trainees and medical officers in the Department of Anaesthesiology at the University of the Free State (UFS) in South Africa.

Results

The CMAC^® had a statistically shorter time to first pass (median 13.8 seconds) compared to the 3D-printed model (median 19.0 seconds) (95% confidence interval [CI] 1.0-6.2; P=0.0013). No failed attempts occurred with either device.

Conclusion

Intubation times were faster with the CMAC^® than with the novel device. However, with a comparable intubation success rate, 3D printing technology potentially can improve access to video laryngoscopy. Further design improvements, validation of materials and manufacturing processes are required before 3D-printed laryngoscope blades can be used in human subjects.

Evaluation of the New SingularityTM Air versus Ambu® Aura GainTM: A Randomized, Crossover Mannequin Study

Background: This randomised crossover mannequin study aimed to compare the insertion time for the newly developed SingularityTM Air and the Ambu® AuraGainTM. The SingularityTM Air includes a bendable tube in order to allow optimal passform. Methods: Fifty anaesthetists with a minimum of 100 supraglottic airway device insertions were recruited and randomly assigned to start either with the SingularityTM Air or with the Ambu® AuraGainTM. Participants watched a tutorial video the day before the assessment and received a standardized introduction immediately before the assessment. The primary outcome was the time for successful insertion. Secondary parameters were the overall insertion success rate, the numbers of insertion attempts (maximum three), the glottic view through a flexible bronchoscope, and the success rate for gastric tube insertion. Results: Fifty participants were eventually recruited and randomly assigned to insert both devices according to the randomization. The insertion time was 24 s for SingularityTM Air as compared to 20 s for Ambu® AuraGainTM (p < 0.001). Overall insertion rate was 92% for the SingularityTM Air as compared to 100% for the Ambu® AuraGainTM (p could not be derived as one variable is a constant). The primary insertion success rate was better for the Ambu® AuraGainTM than for the SingularityTM Air (94% versus 68%; p: 0.002, respectively). Conclusion: The time for successful insertion and the insertion success rate for the newly developed SingularityTM Air is inferior to that for the Ambu® AuraGainTM.

A cadaveric model for transesophageal echocardiography transducer placement training: A pilot study

BACKGROUND

Transesophageal echocardiography (TEE) is used in the emergency department to guide resuscitation during cardiac arrest. Insertion of a TEE transducer requires manual skill and experience, yet in some residency programs cardiac arrest is uncommon, so some physicians may lack the means to acquire the manual skills to perform TEE in clinical practice. For other infrequently performed procedural skills, simulation models are used. However, there is currently no model that adequately simulates TEE transducer insertion. The aim of this study is to evaluate the feasibility and efficacy of using a cadaveric model to teach TEE transducer placement among novice users.

METHODS

A convenience sample of emergency medicine residents was enrolled during a procedure education session using cadavers as tissue models. A pre-session assessment was used to determine prior knowledge and confidence regarding TEE manipulation. Participants subsequently attended a didactic and hands-on education session on TEE placement. All participants practised placing the TEE transducer until they were able to pass a standardized assessment of technical skill (SATS). After the educational session, participants completed a post-session assessment.

RESULTS

Twenty-five residents participated in the training session. Mean assessment of knowledge improved from 6.2/10 to 8.7/10 (95% confidence interval [CI] of knowledge difference 1.6-3.2, P<0.001) and confidence improved from 1.6/5 to 3.1/5 (95% CI of confidence difference 1.1-2.0, P<0.001). There was no relationship between training level and the delta in knowledge or confidence.

CONCLUSIONS

In this pilot study, the use of a cadaveric model to teach TEE transducer placement methods among novice users is feasible and improves both TEE manipulation knowledge and confidence levels.

Anatomic accuracy, physiologic characteristics, and fidelity of very low birth weight infant airway simulators

BACKGROUND

Medical simulation training requires realistic simulators with high fidelity. This prospective multi-center study investigated anatomic precision, physiologic characteristics, and fidelity of four commercially available very low birth weight infant simulators.

METHODS

We measured airway angles and distances in the simulators Premature AirwayPaul (SIMCharacters), Premature Anne (Laerdal Medical), Premie HAL S2209 (Gaumard), and Preterm Baby (Lifecast Body Simulation) using computer tomography and compared these to human cadavers of premature stillbirths. The simulators' physiologic characteristics were tested, and highly experienced experts rated their physical and functional fidelity.

RESULTS

The airway angles corresponded to those of the reference cadavers in three simulators. The nasal inlet to glottis distance and the mouth aperture to glottis distance were only accurate in one simulator. All simulators had airway resistances up to 20 times higher and compliances up to 19 times lower than published reference values. Fifty-six highly experienced experts gave three simulators (Premature AirwayPaul: 5.1 ± 1.0, Premature Anne 4.9 ± 1.1, Preterm Baby 5.0 ± 1.0) good overall ratings and one simulator (Premie HAL S2209: 2.8 ± 1.0) an unfavorable rating.

CONCLUSION

The simulator physiology deviated significantly from preterm infants' reference values concerning resistance and compliance, potentially promoting a wrong ventilation technique.

IMPACT

Very low birth weight infant simulators showed physiological properties far deviating from corresponding patient reference values. Only ventilation with very high peak pressure achieved tidal volumes in the simulators, as aimed at in very low birth weight infants, potentially promoting a wrong ventilation technique. Compared to very low birth weight infant cadavers, most tested simulators accurately reproduced the anatomic angular relationships, but their airway dimensions were relatively too large for the represented body. The more professional experience the experts had, the lower they rated the very low birth weight infant simulators.

[Manikin-based comparison of the use of different supraglottic airways by laypersons]

BACKGROUND

Supraglottic airways (SGA) are an established method of airway management both in prehospital medicine and clinical settings. Endotracheal intubation is the gold standard, but SGA offer advantages in terms of faster application learnability.

OBJECTIVES

In the present study it was investigated whether the time until the first sufficient ventilation in the three examined SGAs applied by bystander differed significantly.

MATERIALS AND METHODS

A total of 160 visitors to a shopping mall were assigned to one of the three SGA after permutative block randomization. The primary endpoint of the present study was the required placement time until the first sufficient ventilation.

RESULTS

Participants managed to place the i‑gel laryngeal mask airway (i-gel, Intersurgical Beatmungsprodukte GmbH, Sankt Augustin, Germany) after a median time of 11 s, whereas the median time until the first sufficient ventilation using a classic laryngeal mask airway (LMA; 26 s) or a laryngeal tube (LT; 28 s) was significantly longer. Thus, the time savings when using the i‑gel compared to the LT and LMA were each significant (p < 0.001), whereas the times between LT and LMA did not differ significantly (p 0.65).

CONCLUSION

The results show that laypersons are able to successfully apply various supraglottic airways to the phantom after a short learning period. The i‑gel laryngeal mask could be placed with the highest success rate and speed.

Anatomic accuracy of airway training manikins compared with humans

Airway simulators, or training manikins, are frequently used in research studies for device development and training purposes. This study was designed to determine the anatomic accuracy of the most frequently used low-fidelity airway training manikins. Computerised tomography scans and ruler measurements were taken of the SynDaver^® , Laerdal^® and AirSim^® manikins. These measurements were compared with human computerised tomography (CT) scans (n = 33) from patients at the University of Michigan Medical Center or previously published values. Manikin measurements were scored as a percentile among the distribution of the same measurements in the human population and 10 out of 27 manikin measurements (nine measurements each in three manikins) were outside of two standard deviations from the mean in the participants. All three manikins were visually identifiable as outliers when plotting the first two dimensions from multidimensional scaling. In particular, the airway space between the epiglottis and posterior pharyngeal wall, through which airway devices must pass, was too large in all three manikins. SynDaver, Laerdal and AirSim manikins do not have anatomically correct static dimensions in relation to humans and these inaccuracies may lead to imprecise airway device development, negatively affect training and cause over-confidence in users.

Does the revised intubating laryngeal tube (ILTS-D2) perform better than the intubating laryngeal mask (Fastrach)? - a randomised simulation research study

BACKGROUND

The intubating laryngeal tube (ILTS-D™) and the intubating laryngeal mask (Fastrach™) are devices that facilitate both extraglottic application and blind tracheal intubation. A revised model of the iLTS-D (for scientific reasons called ILTS-D2) has been designed but not yet evaluated. Therefore, we compared the ILTS-D2 with the established Fastrach under controlled conditions in a prospective randomised controlled simulation research study.

METHODS

After ethical approval, we randomised 126 medical students into two groups. Each participant received either Fastrach or ILTS-D2 to perform five consecutive ventilation attempts in a manikin. The primary endpoint was the time to ventilation in the last attempt of using the devices as extraglottic devices. Secondary endpoints were the time to tracheal intubation and the success rates.

RESULTS

There was no relevant difference between the two devices in the time to ventilation in the last of five attempts (Fastrach: median 14 s [IQR: 12-15]; ILTS-D2: median 13 s [IQR: 12-15], p = 0.592). Secondary endpoints showed a 2 s faster blind tracheal intubation using the Fastrach than using the ILTS-D2 (Fastrach: median 14 s [IQR: 13-17]; ILTS-D2: median 16 s [IQR: 15-20] p < 0.001). For both devices, the success rates were 100% in the last attempt.

CONCLUSIONS

Concerning extraglottic airway management, we could not detect a relevant difference between the revised ILTS-D2 and the Fastrach under laboratory conditions. We advocate for an evaluation of the ILTS-D2 in randomised controlled clinical trials.

TRIAL REGISTRATION

Identifier at clinicaltrials.gov: NCT03542747. May 31, 2018.

Impact of cardiopulmonary resuscitation on a cannot intubate, cannot oxygenate condition: a randomised crossover simulation research study of the interaction between two algorithms

OBJECTIVES

During a 'cannot intubate, cannot oxygenate' situation, asphyxia can lead to cardiac arrest. In this stressful situation, two complex algorithms facilitate decision-making to save a patient's life: difficult airway management and cardiopulmonary resuscitation. However, the extent to which competition between the two algorithms causes conflicts in the execution of pivotal treatment remains unknown. Due to the rare incidence of this situation and the very low feasibility of such an evaluation in clinical reality, we decided to perform a randomised crossover simulation research study. We propose that even experienced healthcare providers delay cricothyrotomy, a lifesaving approach, due to concurrent cardiopulmonary resuscitation in a 'cannot intubate, cannot oxygenate' situation.

DESIGN

Due to the rare incidence and dynamics of such a situation, we conducted a randomised crossover simulation research study.

SETTING

We collected data in our institutional simulation centre between November 2016 and November 2017.

PARTICIPANTS

We included 40 experienced staff anaesthesiologists at our tertiary university hospital centre.

INTERVENTION

The participants treated two simulated patients, both requiring cricothyrotomy: one patient required cardiopulmonary resuscitation due to asphyxia, and one patient did not require cardiopulmonary resuscitation. Cardiopulmonary resuscitation was the intervention. Participants were evaluated by video records.

PRIMARY OUTCOME MEASURES

The difference in 'time to ventilation through cricothyrotomy' between the two situations was the primary outcome measure.

RESULTS

The results of 40 participants were analysed. No carry-over effects were detected in the crossover design. During cardiopulmonary resuscitation, the median time to ventilation was 22 s (IQR 3-40.5) longer than that without cardiopulmonary resuscitation (p=0.028), including the decision-making time.

CONCLUSION

Cricothyrotomy, which is the most crucial treatment for cardiac arrest in a 'cannot intubate, cannot oxygenate' situation, was delayed by concurrent cardiopulmonary resuscitation. If cardiopulmonary resuscitation delays cricothyrotomy, it should be interrupted to first focus on cricothyrotomy.

Comparing Four Video Laryngoscopes and One Optical Laryngoscope with a Standard Macintosh Blade in a Simulated Trapped Car Accident Victim

Background

Tracheal intubation still represents the “gold standard” in securing the airway of unconscious patients in the prehospital setting. Especially in cases of restricted access to the patient, video laryngoscopy became more and more relevant.

Objectives

The aim of the study was to evaluate the performance and intubation success of four different video laryngoscopes, one optical laryngoscope, and a Macintosh blade while intubating from two different positions in a mannequin trial with difficult access to the patient.

Methods

A mannequin with a cervical collar was placed on the driver's seat. Intubation was performed with six different laryngoscopes either through the driver's window or from the backseat. Success, C/L score, time to best view (TTBV), time to intubation (TTI), and number of attempts were measured. All participants were asked to rate their favored device.

Results

Forty-two physicians participated. 100% of all intubations performed from the backseat were successful. Intubation success through the driver's window was less successful. Only with the Airtraq® optical laryngoscope, 100% success was achieved. Best visualization (window C/L 2a; backseat C/L 2a) and shortest TTBV (window 4.7 s; backseat 4.1 s) were obtained when using the D-Blade video laryngoscope, but this was not associated with a higher success through the driver's window. Fastest TTI was achieved through the window (14.2 s) when using the C-MAC video laryngoscope and from the backseat (7.3 s) when using a Macintosh blade.

Conclusions

Video laryngoscopy revealed better results in visualization but was not associated with a higher success. Success depended on the approach and familiarity with the device. We believe that video laryngoscopy is suitable for securing airways in trapped accident victims. The decision for an optimal device is complicated and should be based upon experience and regular training with the device.

[Statement of the Austrian Society for Anesthesiology, Resuscitation and Intensive Care Medicine (ÖGARI) on the use of laryngeal tubes by ambulancemen and paramedics]

Due to an increasing number of severe complications reported during the prehospital application of laryngeal tubes, the Austrian Society for Anesthesiology, Resuscitation and Intensive Care Medicine (ÖGARI) is prompted to formulate a respective statement. With regard to the current training situation and the applicable laws, ÖGARI recommends to convert the "Emergency Competence for Endotracheal Intubation (NKI)" for emergency paramedics into an "Emergency Competence for Extraglottic Airway Management, (NK-EGA)". Training should include at least 40 h of theoretical instruction, hands-on training on the manikin to secure mastery of the methodology and at least 20 successful applications under clinically elective conditions in adult patients under direct medical supervision. Here, depending on local conditions, both laryngeal mask and laryngeal tube can be used. In the prehospital environment, the device must be used which has been trained as mentioned above. Only 2nd generation EGA should be used. After successful EGA placement timely cuff pressure monitoring and gastric suction should be performed. The use of an EGA by ambulance-men cannot be recommended; these have to be limited to bag-mask ventilation.

Prospective Trial to Compare Direct and Indirect Laryngoscopy Using C-MAC PM® with Macintosh Blade and D-Blade® in a Simulated Difficult Airway

Objective. Evaluation of C-MAC PM® in combination with a standard Macintosh blade size 3 in direct and indirect laryngoscopy and D-Blade® in indirect laryngoscopy in a simulated difficult airway. Primary outcome was defined as the best view of the glottic structures. Secondary endpoints were subjective evaluation and assessment of the intubation process. Methods. Prospective monocentric, observational study on 48 adult patients without predictors for difficult laryngoscopy/tracheal intubation undergoing orthopedic surgery. Every participant preoperatively received a cervical collar to simulate a difficult airway. Direct and indirect laryngoscopy w/o the BURP maneuver with a standard Macintosh blade and indirect laryngoscopy w/o the BURP maneuver using D-Blade® were performed to evaluate if blade geometry and the BURP maneuver improve the glottic view as measured by the Cormack-Lehane score. Results. Using a C-MAC PM® laryngoscope, D-Blade® yielded improved glottic views compared with the Macintosh blade used with either the direct or indirect technique. Changing from direct laryngoscopy using a Macintosh blade to indirect videolaryngoscopy using C-MAC PM® with D-Blade® improved the Cormack-Lehane score from IIb, III, or IV to I or II in 31 cases. Conclusion. The combination of C-MAC PM® and D-Blade® significantly enhances the view of the glottis compared to direct laryngoscopy with a Macintosh blade in patients with a simulated difficult airway. Trial Registration Number. This trial is registered under number NCT03403946.

Optimizing education in difficult airway management: meeting the challenge

PURPOSE OF REVIEW

The last 2 decades have seen a vast change in the science and technology of airway management. As a result, there is an increasing need to equip anesthesiologists with the new knowledge and skills for the safe management of a difficult airway.

RECENT FINDINGS

In addition to knowledge and expertise, human factors and nontechnical skills (NTS), including situational awareness, communication and team work, play an important role during difficult airway management and contribute to the outcome. Didactic sessions are useful to impart knowledge. Self-learning, interactive discussions, simulation and debriefing are important tools for teaching and training in difficult airway management. Manikin training and simulation enable development of technical as well as NTS without subjecting patients to risk and allow multiple training sessions of relatively uncommon scenarios. Guidelines are useful teaching tools, whereas cognitive tools such as the Vortex approach may be useful during a difficult airway.

SUMMARY

There is need for research on difficult airway management and optimized training methods. Research is also required to determine the barriers to adoption of guidelines and strategies to ensure widespread dissemination and implementation of guidelines and best practices for difficult airway management.

The novel video-assisted intubating laryngeal mask Totaltrack compared to the intubating laryngeal mask Fastrach - a controlled randomized manikin study

BACKGROUND

The novel Totaltrack combines a supraglottic airway device with video laryngoscopic tracheal intubation. The intubation laryngeal mask Fastrach is an established device without visual control of intubation. We hypothesized that supraglottic ventilation success with Totaltrack would be similar to Fastrach, but intubation would be performed faster due to visual control of the procedure.

METHODS

Fifty-five anaesthesiologists were randomized into one of two study arms: Fastrach Totaltrack. After a standardized introduction, six consecutive attempts of supraglottic ventilation and intubation attempts with each of one of the devices were performed on an airway manikin. The combined primary outcome was: time to supraglottic ventilation and time to ventilation after intubation. Additionally, success rate and learning curves were evaluated.

RESULTS

Supraglottic time to ventilation was shorter when using the Fastrach compared to the Totaltrack (median: 7.8 s [confidence interval [CI]: 7.0-8.6 s] vs. 11 s [CI: 7.8-14.2 s], P < 0.001). Intubation was faster using the Fastrach compared to Totaltrack (median: 12.5 s, [CI: 10.1-14.9 s] vs. 23.3 s [CI: 21.5-25.1 s], P < 0.001). Success rate for supraglottic ventilation was comparable between Fastrach and Totaltrack (86-96%). Successful intubation via the device was 100% in Fastrach and ranged from 61% to 93% in Totaltrack, with a higher probability of successful intubation after four applications.

CONCLUSION

In this manikin-based study the novel Totaltrack did not prove superior to Fastrach despite a similar design. Video laryngoscopic control of supraglottic ventilation and endotracheal intubation was prolonged using the Totaltrack. Clinical trials are mandatory to evaluate the role of the Totaltrack in airway management.

[Preclinical duty of care during cuff pressure management]

BACKGROUND

Airway morbidity is influenced by different factors. Independent of the main emergency health problem, airway morbidity factors may exacerbate a possible poor outcome (e.g., bleeding, tongue swelling, nerve lesion).

OBJECTIVES

However, insertion technique and cuff pressure management are both important for duty of care out-of-hospital emergency medicine. After securing the airway (e.g., tracheal tube or supraglottic airway device cuff), pressure measurement is necessary.

MATERIALS AND METHODS

In a number of recent publications, a largely forgotten issue has come into the focus of preclinical science. This issue became particularly relevant in the admitting hospital.

RESULTS

The results from the aforementioned publications show that preclinical management of cuff pressure is not taken sufficiently into consideration, resulting in possible harm to the patient.

DISCUSSION

It is important and safe to use a cuff pressure device. The initial cuff pressure and if necessary corrected value should be documented.