Learning Curves for Two Fiberscopes in Simulated Difficult Airway Scenario With Cumulative Sum Method

Endobronchial Intubation With the King Vision® and McGrath® Laryngoscopes in Simulated Easy and Difficult Airways by Novices (eKingMath)

Objective. The competency of using video laryngoscopes (VL) for double-lumen tube (DLT) endobronchial intubations can be improved with constant training as assessed by measuring the learning curves. We hypothesized that the time to DLT intubation would be reduced over the intubation attempts. Design. A crossover manikin study. Settings. University-affiliated hospital. Participants. Forty-two novice medical students unfamiliar with DLT intubation. Interventions. Participants were randomly allocated to two sequences, including DLT intubation, using King Vision and McGrath VLs. Each participant completed 100 DLT intubation attempts on both simulated easy and difficult airways on two different mannikins using the study devices (25 attempts for each). Measurements and Main Results. The primary outcome was the time to DLT intubation. The secondary outcomes included the best glottic view, optimizing maneuvers, and intubation first-pass success. The use of King Vision VL was associated with a significantly shorter time to DLT intubation (P < 0.044 and P < 0.05, respectively) and a higher percentage of glottic opening (POGO) compared to the McGrath VL (P < 0.011 and P < 0.002, respectively) in the simulated "easy" and "difficult" over most of the intubation attempts. In the simulated "easy" airway, the first-pass success ratio was higher when using the King Vision VL (median [Minimum-Maximum] 100% [100%-100%] and 100% [88%-100%], P = 0.012). Conclusion. Novice medical students developed skills over intubation attempts, meaning achievement of a faster DLT intubation, better laryngeal exposure, and higher success rate on simulated "easy" and "difficult" airways. A median of 9 DLT intubations was required to achieve a 92% or greater DLT intubation success rate.

A learning curve of a novel multimodal endotracheal intubation assistant device for novices in a simulated airway: a prospective manikin trial with cumulative sum method

BACKGROUND

Awake fiberoptic intubation is conventionally performed in anticipated difficult airways. However, obstruction by secretions and sputum makes it challenging for novices. A prototype of a novel multimodal endotracheal intubation assistant device (MEIAD) was developed for an indication of airway according to end-tidal carbon dioxide (ETCO₂) and image. At the tip, 4 sampling tubes collected ETCO₂ concentration. The airway direction is located according to an advanced algorithm based on 4 directions' concentrations. It assists awake intubation, especially with unclear view field. The objective was to analyze the learning curve of MEIAD for novices on a manikin by cumulative sum method (CUSUM) and evaluate the utility.

METHODS

A total of 16 novice residents with less than 2-year clinical experience were enrolled. After instruction, each individual exercised 40 insertions with MEIAD on a difficult airway simulation. Insertion success (defined as a visualization of the carina within 120 seconds), insertion time (the time from when the guiding scope entered the nasal cavity to the carina was visible), and self-confidence score (subjective score with a numerical rating scale from 0 to 10) were recorded. The acceptable and unacceptable failure rates of CUSUM were set as 15% and 30%, respectively. The exercises were divided into 2 phases (phase 1: 1-20, phase 2: 21-40) for further evaluation. All continuous data were expressed by median (IQR, interquartile ranges) and analyzed using Mann-Whitney test. All categorical variables were expressed as percentages and compared by the χ² test.

RESULTS

Among the 16 residents, 15 were able to cross the lower decision boundary in an average of 21.27±9.51 attempts using the novel device. The insertion time [24.0 (17.0-42.0) vs. 17.5 (14.0-28.0) seconds, P<0.001] and success rate (88.4% vs. 97.5%, P<0.001) were improved with increased experience. The confidence score was significantly improved from 2.5 (1.3-4.0) to 7.0 (7.0-8.0).

CONCLUSIONS

MEIAD showed a satisfactory learning curve and efficacy on the manikin for novices. However, as a small exploratory manikin trial, the results cannot be replicated in clinical practice. MEIAD is expected to be further improved and potential to be an alternative device for difficult airways.

Learning curve and performance in simulated difficult airway for the novel C-MAC® video-stylet and C-MAC® Macintosh video laryngoscope: A prospective randomized manikin trial

Difficult airways can be managed with a range of devices, with video laryngoscopes (VLs) being the most common. The C-MAC® Video-Stylet (VS; Karl-Storz Germany), a hybrid between a flexible and a rigid intubation endoscope, has been recently introduced. The aim of this study is to investigate the performance of the VS compared to a VL (C-MAC Macintosh blade, Karl-Storz Germany) with regards to the learning curve for each device and its ability to manage a simulated difficult airway manikin. This is a single-center, prospective, randomized, crossover study involving twenty-one anesthesia residents performing intubations on a Bill 1™ (VBM, Germany) airway manikin model. After a standardized introduction, six randomized attempts with VL and VS were performed on the manikin. This was followed by intubation in a simulated difficult airway (cervical collar and inflated tongue) with both devices in a randomized fashion. The primary end-point of this study was the total time to intubation. All continuous variables were expressed as the median [interquartile range] and analyzed using the Mann-Whitney U test. A 2-way ANOVA with Bonferroni's post hoc test was used to compare both devices at each trial. All reported p values are two sided. The median total time to intubation on a simulated difficult airway was faster with the VS compared to VL (17 [13.5-25] sec vs 23 [18.5-26.5] sec, respectively; 95% CI; P = 0.031). Additionally, on a normal airway manikin, the VS has a comparable learning curve to the VL. In this manikin-based study, the novel VS was comparable to the VL in terms of learning curve in a normal airway. In a simulated difficult airway, the total time to intubation, though likely not clinically relevant, was faster with the VS to the VL. However, given the above findings, this study justifies further human clinical trials with the VS to see if similar benefits-faster time to intubation and similar learning curve to VL-are replicated clinically.

The skill of tracheal intubation with rigid scopes - a randomised controlled trial comparing learning curves in 740 intubations

Background

Rigid scopes are successfully used for management of difficult airways, but learning curves have not been established.

Methods

This randomised controlled trial was performed at the University Hospital Bern in Switzerland to establish learning curves for the rigid scopes Bonfils and SensaScope and to assess their performance. Fifteen consultant anaesthetists and 15 anaesthesia registrars performed a total of 740 intubations (10 to 20 intubations with each device per physician) in adult patients without predictors of a difficult airway under general anaesthesia. According to randomisation, physicians intubated the patient’s trachea with either the Bonfils or the SensaScope. A maximum of three intubation attempts was allowed. Primary outcome was overall time to successful intubation. Secondary outcome parameters included first attempt success, first attempt success within 60 s, failures and adverse events.

Results

A clear learning effect was demonstrated: Over 20 trials, intubations became 2.5-times quicker and first attempt intubation success probability increased by 21–28 percentage points. Fourteen and 20 trials were needed with the Bonfils and the SensaScope, respectively, to reach a 90% first attempt success probability. Intubation times were 23% longer (geometric mean ratio 1.23, 95% confidence interval 1.12–1.36, p < 0.001) and first attempt success was less likely (odds ratio 0.64, 95% confidence interval 0.45–0.92, p = 0.016) with the SensaScope. Consultants showed a tendency for a better first attempt success compared to registrars. Overall, 23 intubations (10 Bonfils, 13 SensaScope) failed. Adverse events were rare and did not differ between devices.

Conclusions

A clear learning effect was demonstrated for both rigid scopes. Fourteen intubations with the Bonfils and 20 intubations with the SensaScope were required to reach a 90% first attempt success probability. Learning of the technique seemed more complex with the SensaScope compared to the Bonfils.

Trial registration

Current Controlled Trials, ISRCTN14429285. Registered 28 September 2011, retrospectively registered.