Forces applied to the maxillary incisors during tracheal intubation and dental injury risks of intubation by beginners: a manikin study

Protective potential of different mouthguard thicknesses against perianaesthetic dental trauma: a patient specific-finite element study

Perianaesthetic dental trauma is a common anaesthesia-related complication. Theprevious studies have shown a lack of knowledge regarding mouthguard usage and controversial results related to perianaesthetic dental trauma prevention. This study aimed to conduct a finite element analysis of the compressive and tensile stresses on the tooth-periodontal ligament-bone complex using custom-made mouthguards of different thicknesses and glass fibre splints to prevent perianaesthetic dental trauma. Custom-fitted ethylene-vinyl acetate mouthguards of two different thicknesses (2 and 3 mm) and glass fibre splint were modelled. A linear static finite element analysis was performed by applying a rigid Macintosh laryngoscope to the palatal surface of the maxillary central incisors at 150 N. The model without a mouthguard and glass fibre splint showed the highest stress values at the palatinal root surfaces during the impact. Increasing the mouthguard thickness significantly decreased the stress-strain values regardless of the presence of the glass fibre splint. Maximum stresses in the group using the 3 mm mouthguard were the lowest compared with the other groups.

Teeth Damage during General Anesthesia

INTRODUCTION

Dental injuries during anesthesia, especially when advanced airway management is required, represent a legal problem. Factors such as poor dental condition and excessive pressure during intubation contribute to dental damage. The maxillary central incisors are commonly affected.

OBJECTIVE

The objective of this review is to know the incidence of dental injuries in adults undergoing anesthesia that requires airway management.

MATERIALS AND METHODS

The search was performed in MEDLINE (through Pubmed), ClinicalTrials.gov, Scopus, LILACS (through the Virtual Health Library Regional Portal), and SciELO for all available literature on the subject up to December 2022. Inclusion criteria involved articles that studied patients aged 18 years or older who underwent general anesthesia requiring airway management with tracheal intubation or insertion of a laryngeal mask airway.

RESULTS

Of all the articles, nine report dental injury associated with the type of airway management. Only one article does not have dental injury.

DISCUSSION

This study addresses dental injuries related to tracheal intubation during general anesthesia. Although techniques are used to prevent them, these injuries still occur. Laryngoscopy, especially with support on the upper central incisors, can cause damage to the teeth.

CONCLUSIONS

It is important that the anesthesiologist is aware of dental trauma and that orotracheal intubation or the placement of the laryngeal mask airway is performed systematically and rigorously, always considering the patient's dentition to choose the best approach in each specific situation.

Predicting Trainee Clinical Success From Performance at Simulated Endotracheal Intubation

INTRODUCTION

Multiple attempts and failure at endotracheal intubation (ETI) are common for inexperienced practitioners and can cause patient morbidity. A test to predict a provider's likelihood of success at patient ETI could assist decisions about training. This project investigated whether trainees' performance at laryngoscopy on airway mannequins predicted their laryngoscopy outcomes in patients.

METHODS

Twenty-one consenting first-year anesthesiology residents, emergency medicine residents, and medical students enrolled in this prospective, observational study. They performed laryngoscopy and ETI with a curved laryngoscope on 4 airway mannequins. Metrics included peak dental force, procedure duration, esophageal intubation, laryngeal view, and first-pass ETI success on the mannequins. Trainee data from 203 patient ETIs were collected over a roughly 2-month period centered around the simulation test. Multivariable logistic regression analyzed the relationship of mannequin metrics, participant experience, and a patient difficult airway score with trainee ETI outcomes in patients.

RESULTS

Median trainee first-pass success rate at patient ETI was 63%, the rate of ETI problems was 16%, and the esophageal intubation rate was 6%. Laryngoscopy peak dental force, first-pass ETI success, and duration on individual mannequins were significant predictors of patient ETI first-pass success. Metrics from 2 of the 4 mannequins predicted ETI problems.

DISCUSSION

Performance metrics from simulated laryngoscopy predicted trainee outcomes during patient ETI. First-pass success and ETI problems affect patient safety and are related to trainee skill. Mannequin laryngoscopy tests could identify trainees who would benefit from additional practice. The metrics could be surrogate end points in research to optimize simulated laryngoscopy training.

Does seniority always correlate with simulated intubation performance? Comparing endotracheal intubation performance across medical students, residents, and physicians using a high-fidelity simulator

Background

Endotracheal intubation is crucial in emergency medical care and anaesthesia. Our study employed a high-fidelity simulator to explore differences in intubation success rate and other skills between junior and senior physicians.

Methods

We examined the performance of 50 subjects, including undergraduate students (UGY), postgraduate trainees (PGY), residents (R), and attending physicians (VS). Each participant performed 12 intubations (i.e. 3 devices x 4 scenarios) on a high-fidelity simulator. Main outcome measures included success rate, time for intubation, force applied on incisor and tongue, and Cormack Lehane grades.

Results

There was no primary effect of seniority on any outcome measure except success rate and Cormack Lehane grades. However, VS demonstrated shorter duration than medical students using Glidescope and direct laryngoscopy, whereas VS and R applied significantly more force on the incisor in the normal airway and rigid neck scenario respectively.

Discussion

Seniority does not always correlate with skill perfection in detailed processes. Our study suggests that the use of video laryngoscopy enhances the intubation success rate and speed, but the benefit only accrues to senior learners, whereby they applied more force on the incisor at a single peak under difficult scenarios. These findings are discussed in terms of psychological and cognitive perspectives.

Conclusion

Speed and safety are essential for high quality critical medical procedures. A tool should be designed and implemented to educate junior physicians with an emphasis on practice and efficiency, which should also contribute to updating senior physicians’ knowledge and competence by providing instant feedback on their performance. This type of fine-grained feedback could serve as a complement to traditional training and provide a sustainable learning model for medical education.

Lower maximum forces on oral structures when using gum-elastic bougie than when using endotracheal tube and stylet during both direct and indirect laryngoscopy by novices: a crossover study using a high-fidelity simulator

BACKGROUND

Applying excessive force during endotracheal intubation (ETI) is associated with several complications, including dental trauma and hemodynamic alterations. A gum-elastic bougie (GEB), a type of tracheal tube introducer, is a useful airway adjunct for patients with poor laryngoscopic views. However, how the use of a GEB affects the force applied during laryngoscopy is unclear. We compared the force applied on the oral structures during ETI performed by novices using the GEB versus an endotracheal tube + stylet.

METHODS

This prospective crossover study was conducted from April 2017 to March 2019 in a public medical university in Japan. In total, 209 medical students (4th and 5th grade, mean age of 23.7 ± 2.0 years) without clinical ETI experience were recruited. The participants used either a Macintosh direct laryngoscope (DL) or C-MAC video laryngoscope (VL) in combination with a GEB or stylet to perform ETI on a high-fidelity airway management simulator. The order of the first ETI method was randomized to minimize the learning curve effect. The outcomes of interest were the maximum forces applied on the maxillary incisors and tongue during laryngoscopy. The implanted sensors in the simulator quantified these forces automatically.

RESULTS

The maximum force applied on the maxillary incisors was significantly lower when using a GEB than when using an endotracheal tube + stylet both with the Macintosh DL (39.0 ± 23.3 vs. 47.4 ± 32.6 N, P < 0.001) and C-MAC VL (38.9 ± 18.6 vs. 42.0 ± 22.1 N, P < 0.001). Similarly, the force applied on the tongue was significantly lower when using a GEB than when using an endotracheal tube + stylet both with the Macintosh DL (31.9 ± 20.8 vs. 37.8 ± 22.2 N, P < 0.001) and C-MAC VL (35.2 ± 17.5 vs. 38.4 ± 17.5 N, P < 0.001).

CONCLUSIONS

Compared with the use of an endotracheal tube + stylet, the use of a GEB was associated with lower maximum forces on the oral structures during both direct and indirect laryngoscopy performed by novices. Our results suggest the expanded role of a GEB beyond an airway adjunct for difficult airways.

Impact of Quantitative Feedback via High-Fidelity Airway Management Training on Success Rate in Endotracheal Intubation in Undergraduate Medical Students-A Prospective Single-Center Study

Endotracheal intubation is still the gold standard in airway management. For medical students and young professionals, it is often difficult to train personal skills. We tested a high-fidelity simulator with an additional quantitative feedback integration to elucidate if competence acquisition for airway management is increased by using this feedback method. In the prospective trial, all participants (n = 299; 4th-year medical students) were randomized into two groups—One had been trained on the simulator with additional quantitative feedback (n = 149) and one without (n = 150). Three simulator measurements were considered as quality criteria—The pressure on the upper front row of teeth, the correct pressure point of the laryngoscope spatula and the correct depth for the fixation of the tube. There were a total of three measurement time points—One after initial training (with additional capture of cognitive load), one during the exam, and a final during the follow-up, approximately 20 weeks after the initial training. Regarding the three quality criteria, there was only one significant difference, with an advantage for the control group with respect to the correct pressure point of the laryngoscope spatula at the time of the follow-up (p = 0.011). After the training session, the cognitive load was significantly higher in the intervention group (p = 0.008) and increased in both groups over time. The additional quantitative feedback of the airway management trainer brings no measurable advantage in training for endotracheal intubation. Due to the increased cognitive load during the training, simple airway management task training may be more efficient for the primary acquisition of essential procedural steps.

Comparison of forces acting on maxillary incisors during tracheal intubation with different laryngoscopy techniques: a blinded manikin study

Dental trauma is a common complication of tracheal intubation. As existing evidence is insufficient to validly assess the impact of different laryngoscopy techniques on the incidence of dental trauma, the force exerted onto dental structures during tracheal intubation was investigated. An intubation manikin was equipped with hidden force sensors in all maxillary incisors. Dental force was measured while 104 anaesthetists performed a series of tracheal intubations using direct laryngoscopy with a Macintosh blade, and videolaryngoscopy with a C-MAC^® , or the hyperangulated GlideScope^® or KingVision^® laryngoscopes in both normal and difficult airway conditions. A total of 624 tracheal intubations were analysed. The median (IQR [range]) peak force of direct laryngoscopy in normal airways was 21.1 (14.0-32.8 [2.3-127.6]) N and 29.3 (17.7-44.8 [3.3-97.2]) N in difficult airways. In normal airways, these were lower with the GlideScope and KingVision hyperangulated laryngoscopes, with a reduction of 4.6 N (p = 0.006) and 10.9 N (p < 0.001) compared with direct laryngoscopy, respectively. In difficult airways, these were lower with the GlideScope and KingVision hyperangulated laryngoscopes, with a reduction of 9.8 N (p < 0.001) and 17.6 N (p < 0.001) compared with direct laryngoscopy, respectively. The use of the C-MAC did not have an impact on the median peak force. Although sex of anaesthetists did not affect peak force, more experienced anaesthetists generated a higher peak force than less experienced providers. We conclude that hyperangulated videolaryngoscopy was associated with a significantly decreased force exerted on maxillary incisors and might reduce the risk for dental injury in clinical settings.

Mechanical strain to maxillary incisors during direct laryngoscopy

Background

While most Direct laryngoscopy leads to dental injury in 25–39% of cases. Dental injury occurs when the forces and impacts applied to the teeth exceed the ability of the structures to dissipate energy and stress. The purpose of this study was to measure strain, (which is the change produced in the length of the tooth by a force applied to the tooth) strain rate, and strain-time integral to the maxillary incisors and determine if they varied by experience, type of blade, or use of an alcohol protective pad (APP).

Methods

A mannequin head designed to teach and test intubation was instrumented with eight single axis strain gauges placed on the four maxillary incisors: four on the facial or front surface of the incisors and four on the lingual or back, near the insertion of the incisor in the gums to measure bending strain as well as compression. Anesthesiology faculty, residents, and certified registered nurse anesthetists intubated with Macintosh and Miller blades with and without APP. Using strain-time curves, the maximum strain, strain rate, and strain time integral were calculated.

Results

Across the 92 subjects, strain varied 8–12 fold between the 25th and 75th percentiles for all four techniques, but little by experience, while strain rate and strain integral varied 6–13 fold and 15–26 fold, respectively, for the same percentiles. Intubators who had high strain values with one blade tended to have high strains with the other blade with and without the APP (all pairwise correlation rho = 0.42–0.63).

Conclusions

Strain varies widely by intubator and that the use of the APP reduces strain rate which may decrease the risk of or the severity of dental injury.

Comparison of the force applied on oral structures during intubation attempts by novice physicians between the Macintosh direct laryngoscope, Airway Scope and C-MAC PM: a high-fidelity simulator-based study

OBJECTIVE

We examined whether the use of Airway Scope (AWS) and C-MAC PM (C-MAC) decreased the force applied on oral structures during intubation attempts as compared with the force applied with the use of Macintosh direct laryngoscope (DL).

DESIGN

Prospective cross-over study.

PARTICIPANTS

A total of 35 novice physicians participated.

INTERVENTIONS

We used 6 simulation scenarios based on the difficulty of intubation and intubation devices.

OUTCOME MEASURES

Our primary outcome measures were the maximum force applied on the maxillary incisors and tongue during intubation attempts, measured by a high-fidelity simulator.

RESULTS

The maximum force applied on maxillary incisors was higher with the use of the C-MAC than with the DL and AWS in the normal airway scenario (DL, 26 Newton (N); AWS, 18 N; C-MAC, 52 N; p<0.01) and the difficult airway scenario (DL, 42 N; AWS, 24 N; C-MAC, 68 N; p<0.01). In contrast, the maximum force applied on the tongue was higher with the use of the DL than with the AWS and C-MAC in both airway scenarios (DL, 16 N; AWS, 1 N; C-MAC, 7 N; p<0.01 in the normal airway scenario; DL, 12 N; AWS, 4 N; C-MAC, 7 N; p<0.01 in the difficult airway scenario).

CONCLUSIONS

The use of C-MAC, compared with the DL and AWS, was associated with the higher maximum force applied on maxillary incisors during intubation attempts. In contrast, the use of video laryngoscopes was associated with the lower force applied on the tongue in both airway scenarios, compared with the DL. Our study was a simulation-based study, and further research on living patients would be warranted.

Fiber-Reinforced Framework in Conjunction with Porcelain Veneers for the Esthetic Replacement of a Congenitally Missing Maxillary Lateral Incisor: A Case Study

This article presents a case of a congenitally missing right maxillary lateral incisor and the contralateral incisor with discolored composite resin restorations. The technique of fiber reinforcement in conjunction with porcelain veneers was used to provide a satisfactory outcome for the patient. The key learning points of the article are the following: proper diagnosis, treatment plan and appropriate utilization of materials are mandatory for a successful result.