Cormack-Lehane classification revisited

Investigating Users' Attitudes Toward Automated Smartwatch Cardiac Arrest Detection: Cross-Sectional Survey Study

Background

Out-of-hospital cardiac arrest (OHCA) is a leading cause of mortality in the developed world. Timely detection of cardiac arrest and prompt activation of emergency medical services (EMS) are essential, yet challenging. Automated cardiac arrest detection using sensor signals from smartwatches has the potential to shorten the interval between cardiac arrest and activation of EMS, thereby increasing the likelihood of survival.

Objective

This cross-sectional survey study aims to investigate users' perspectives on aspects of continuous monitoring such as privacy and data protection, as well as other implications, and to collect insights into their attitudes toward the technology.

Methods

We conducted a cross-sectional web-based survey in the Netherlands among 2 groups of potential users of automated cardiac arrest technology: consumers who already own a smartwatch and patients at risk of cardiac arrest. Surveys primarily consisted of closed-ended questions with some additional open-ended questions to provide supplementary insight. The quantitative data were analyzed descriptively, and a content analysis of the open-ended questions was conducted.

Results

In the consumer group (n=1005), 90.2% (n=906; 95% CI 88.1%-91.9%) of participants expressed an interest in the technology, and 89% (n=1196; 95% CI 87.3%-90.7%) of the patient group (n=1344) showed interest. More than 75% (consumer group: n= 756; patient group: n=1004) of the participants in both groups indicated they were willing to use the technology. The main concerns raised by participants regarding the technology included privacy, data protection, reliability, and accessibility.

Conclusions

The vast majority of potential users expressed a strong interest in and positive attitude toward automated cardiac arrest detection using smartwatch technology. However, a number of concerns were identified, which should be addressed in the development and implementation process to optimize acceptance and effectiveness of the technology.

Emergency Medicine Postgraduate Year, Laryngoscopic View, and Endotracheal Tube Placement Success

STUDY OBJECTIVE

Prior work has found first-attempt success improves with emergency medicine (EM) postgraduate year (PGY). However, the association between PGY and laryngoscopic view - a key step in successful intubation - is unknown. We examined the relationship among PGY, laryngoscopic view (ie, Cormack-Lehane view), and first-attempt success.

METHODS

We performed a retrospective analysis of the National Emergency Airway Registry, including adult intubations by EM PGY 1 to 4 resident physicians. We used inverse probability weighting with propensity scores to balance confounders. We used weighted regression and model comparison to estimate adjusted odds ratios (aOR) with 95% confidence intervals (CIs) between PGY and Cormack-Lehane view, tested the interaction between PGY and Cormack-Lehane view on first-attempt success, and examined the effect modification of Cormack-Lehane view on the association between PGY and first-attempt success.

RESULTS

After exclusions, we included 15,453 first attempts. Compared to PGY 1, the aORs for a higher Cormack-Lehane grade did not differ from PGY 2 (1.01; 95% CI 0.49 to 2.07), PGY 3 (0.92; 0.31 to 2.73), or PGY 4 (0.80; 0.31 to 2.04) groups. The interaction between PGY and Cormack-Lehane view was significant (P-interaction<0.001). In patients with Cormack-Lehane grade 3 or 4, the aORs for first-attempt success were higher for PGY 2 (1.80; 95% CI 1.17 to 2.77), PGY 3 (2.96; 1.66 to 5.27) and PGY 4 (3.10; 1.60 to 6.00) groups relative to PGY 1.

CONCLUSION

Compared with PGY 1, PGY 2, 3, and 4 resident physicians obtained similar Cormack-Lehane views but had higher first-attempt success when obtaining a grade 3 or 4 view.

The effect of a dedicated intensivist staffing to a medical emergency team on airway management in general wards

Although medical emergency teams (METs) have been widely introduced, studies on the importance of a dedicated intensivist staffing to METs are lacking. A single-center retrospective before-and-after study was performed. Deteriorating patients who required emergency airway management in general wards by MET were included in this study. We divided the study period according to the presence of a dedicated intensivist staff in MET: (1) non-staffed period (from January 2016 to February 2018, n = 971) and (2) staffed period (from March 2018 to December 2019, n = 651), and compared emergency airway management-related variables and outcomes between the periods. Among 1622 patients included, mean age was 63.0 years and male patients were 64.2% (n = 1042). The first-pass success rate was significantly increased in the staffed period (85.9% in the non-staffed vs 89.2% in the staffed; P = .047). Compliance to rapid sequence intubation was increased (9.4% vs 34.4%; P < .001) and vocal cords were more clearly open (P < .001) in the staffed period. The SpO2/FiO2 ratio (median [interquartile range], 125 [113-218] vs 136 [116-234]; P = .007) and the ROX index (4.6 [3.4-7.6] vs 5.1 [3.6-8.5]; P = .013) at the time of intubation was higher in the staffed period, suggesting the decision on intubation was made earlier. The post-intubation hypoxemia was less commonly occurred in the staffed period (7.2% vs 4.2%, P = .018). In multivariate analysis, the rank of operator was a strong predictor of the first-pass success (adjusted OR [95% CI], 2.280 [1.639-3.172]; P < .001 for fellow and 5.066 [1.740-14.747]; P < .001 for staff, relative to resident). In our hospital, a dedicated intensivist staffing to MET was associated with improved emergency airway management in general wards. Staffing an intensivist to MET needs to be encouraged to improve the performance of MET and the patient safety.

To compare the efficacy of the between-the-fingers grip with the conventional pen-holding grip to hold an endotracheal tube for orotracheal intubation: A randomised controlled trial

Background and Aims

Correctly holding the endotracheal tube (ETT) is essential for successful tracheal intubation. The study's primary objective was to compare the between-the-fingers grip with the conventional pen-holding grip regarding the number of attempts required for orotracheal intubation and usage of external aids.

Methods

Three hundred patients undergoing elective surgeries under general anaesthesia were randomised according to the method to hold the ETT to Group C (conventional grip) and Group M (modified, between-the-fingers grip) during oro-tracheal intubation. A designated anaesthetist blinded to the groups performed laryngoscopy in all the patients, and difficult Cormack-Lehane grade 3b and 4 (n = 24) were excluded. Then, the group was revealed to the anaesthetist, and intubation was done accordingly; the number of attempts, use of backward upward rightward pressure (BURP), and time taken were noted. The sample size was estimated using the software G*Power version 3.1.9.2. Statistical Package for Social Sciences, version 23 (SPSS-23, IBM, Chicago, USA) was used for data analysis.

Results

Single-attempt intubation was comparable between the groups (99.3% versus 97.2%, P = 0.197). In contrast, the external assistance as BURP (0.75% versus 6.99%, P = 0.009) and the time taken for intubation (P = 0.008) were reduced in group M significantly.

Conclusion

The between-the-fingers grip seems as effective as the standard grip to hold the ETT during intubation. However, it proved to be better as it can reduce the requirement for external assistance in BURP.

Articulating Video Stylet Compared to Other Techniques for Endotracheal Intubation in Normal Airways: A Simulation Study in Consultants with No Prior Experience

Simulation for airway management allows for acquaintance with new devices and techniques. Endotracheal intubation (ETI), most commonly performed with direct laryngoscopy (DL) or video laryngoscopy (VLS), can be achieved also with combined laryngo-bronchoscopy intubation (CLBI). Finally, an articulating video stylet (ProVu) has been recently introduced. A single-center observational cross-sectional study was performed in a normal simulated airway scenario comparing DL, VLS-Glidescope, VLS-McGrath, CLBI and ProVu regarding the success rate (SR) and corrected time-to-intubation (cTTI, which accounts for the SR). Up to three attempts/device were allowed (maximum of 60 s each). Forty-two consultants with no experience with ProVu participated (15 ± 9 years after training completion). The DL was significantly faster (cTTI) than all other devices (p = 0.033 vs. VLSs, and p < 0.001 for CLBI and Provu), no differences were seen between the two VLSs (p = 0.775), and the VLSs were faster than CLBI and ProVu. Provu had a faster cTTI than CLBI (p = 0.004). The DL and VLSs showed similar SRs, and all the laryngoscopes had a higher SR than CLBI and ProVu at the first attempt. However, by the third attempt, the SR was not different between the DL/VLSs and ProVu (p = 0.241/p = 0.616); ProVu was superior to CLBI (p = 0.038). In consultants with no prior experience, ProVu shows encouraging results compared to DL/VLSs under simulated normal airway circumstances and further studies are warranted.

Identification of difficult laryngoscopy using an optimized hybrid architecture

BACKGROUND

Identification of difficult laryngoscopy is a frequent demand in cervical spondylosis clinical surgery. This work aims to develop a hybrid architecture for identifying difficult laryngoscopy based on new indexes.

METHODS

Initially, two new indexes for identifying difficult laryngoscopy are proposed, and their efficacy for predicting difficult laryngoscopy is compared to that of two conventional indexes. Second, a hybrid adaptive architecture with convolutional layers, spatial extraction, and a vision transformer is proposed for predicting difficult laryngoscopy. The proposed adaptive hybrid architecture is then optimized by determining the optimal location for extracting spatial information.

RESULTS

The test accuracy of four indexes using simple model is 0.8320. The test accuracy of optimized hybrid architecture using four indexes is 0.8482.

CONCLUSION

The newly proposed two indexes, the angle between the lower margins of the second and sixth cervical spines and the vertical direction, are validated to be effective for recognizing difficult laryngoscopy. In addition, the optimized hybrid architecture employing four indexes demonstrates improved efficacy in detecting difficult laryngoscopy.

TRIAL REGISTRATION

Ethics permission for this research was obtained from the Medical Scientific Research Ethics Committee of Peking University Third Hospital (IRB00006761-2015021) on 30 March 2015. A well-informed agreement has been received from all participants. Patients were enrolled in this research at the Chinese Clinical Trial Registry ( http://www.chictr.org.cn , identifier: ChiCTR-ROC-16008598) on 6 June 2016.

Bed tilt and ramp positions are associated with increased first-pass success of adult endotracheal intubation in the emergency department: A registry study

OBJECTIVE

Successful endotracheal intubation in the ED requires optimum body positioning. In patients with obesity, the ramp position was suggested to achieve better intubating conditions. However, limited data are available on the airway management practices for patients with obesity in Australasian EDs. The aim of this study was to identify current patient positioning practices during endotracheal intubation and its association with first-pass success (FPS) at intubation and adverse event (AE) rates in obese and non-obese populations.

METHODS

Prospectively collected data from the Australia and New Zealand ED Airway Registry (ANZEDAR) between 2012 and 2019 were analysed. Patients were categorised into two groups according to their weight: <100 kg (non-obese) or ≥100 kg (obese). Four position categories were investigated; supine, pillow or occipital pad, bed tilt and ramp or head-up with relation to FPS and complication rate using logistic regression modelling.

RESULTS

A total of 3708 intubations from 43 EDs were included. Overall, the non-obese cohort had a greater FPS rate (85.9%) compared to the obese group (77.0%). The bed tilt position had the highest FPS rate (87.2%), whereas the supine position had the lowest (83.0%). AE rates were highest in the ramp position (31.2%) compared to all other positions (23.8%). Regression analysis showed ramp, or bed tilt positions and a consultant-level intubator were associated with higher FPS. Obesity, in addition to other factors, was independently associated with lower FPS.

CONCLUSION

Obesity was associated with lower FPS, which could be improved through performing a bed tilt or ramp positioning.

A taxonomy of key performance errors for emergency intubation

STUDY OBJECTIVE

Currently the videographic review of emergency intubations is an unstructured, qualitative process. We created a taxonomy of errors that impede the optimal procedural performance of emergency intubation.

METHODS

This was a prospective, observational, study reviewing a convenience sample of deidentified laryngoscopy recordings of emergency department intubations that were qualitatively flagged before the study as demonstrating suboptimal technique. These videos were coded for the presence of 13 predetermined performance errors. Our primary outcome was the incidence of each of these specified errors during emergency intubation. Errors fell into 3 categories: errors of structure recognition during laryngoscope insertion, errors of vallecula manipulation, and errors of device delivery.

RESULTS

A total of 100 intubation attempts were reviewed. The most common error was inadequate lifting force with the blade tip in the vallecula which lowered the percent of glottic opening, occurring in 45% of the attempts. The least common performance error was the premature removal of the laryngoscope during bougie placement, occurring in only 9% of the videos.

CONCLUSION

We developed a taxonomy of 13 performance errors of laryngoscopy. Further study is warranted to determine how to best incorporate these into emergency airway training and the airway review process.

Success rates of endotracheal intubation using the standard method versus the modified-ramped position

Background

The sniffing position used in intubation has disadvantages, including suboptimal glottic view, respiratory problems, increased risk of aspiration, and pain. In this regard, we have proposed new conditions to facilitate intubation and tube placement in patients with a Mallampati score higher than 2, by introducing a new position called the modified rapid airway management positioner (RAMP) position. The authors compared various parameters to improve intubation conditions between these two positions.

Methods

This intervention is a randomized clinical trial study, with a random sampling method that divides the patients into two groups: a control group placed in the standard position (S) and an intervention group placed in the modified (M) RAMP position. An anesthesiologist performed intubation. In group (S), patients were placed in the supine position as usual, and a pillow with a height of 10 cm was placed under their heads. In group (M), the patients were placed in the supine position on a modified RAMP with a triangular shape, 15 cm in height, and 80 cm in length, at a 30° angle. The pillow had lengths of 20 and 80 cm.

Results

In the present study, 112 patients were investigated, consisting of 58 women (51.8%) and 54 men (48.2%). The intubation time in the intervention group using the modified RAMP roll technique was significantly shorter (51.25 s) compared to the control group using the standard method (88.39 s) (P=0.019).

Conclusion

The results of the study showed that the modified RAMP roll improved the general conditions of intubation and led to a better view of the glottis in direct laryngoscopy. This is a very important aspect of intubation, and with a better view of the pharynx and glottis, the intubation procedure can be performed with higher quality, reducing the number of intubation attempts and the duration of the procedure.

Modified anterior approach versus traditional posterior approach for ultrasound-guided superior laryngeal nerve block in awake endotracheal intubation: a randomized non-inferiority clinical trial

STUDY OBJECTIVE

This study was undertaken to compare the effect of the modified ultrasound-guided anterior superior laryngeal nerve block (SLNB) with the traditional ultrasound-guided posterior SLNB in providing intubation conditions during awake tracheal intubation (ATI) in patients without difficult airway.

DESIGN

Randomized, assessor-blind. Registration number: ChiCTR2200058086.

SETTING

West China Hospital of Sichuan University, Chengdu, China.

PATIENTS

104 patients aged 18-65 years, of American Society of Anesthesiologists status I-III, posted for elective general surgery with general endotracheal anesthesia.

INTERVENTIONS

The patients were randomized into two groups (modified group, n = 52; traditional group, n = 52). Modified anterior SLNB or traditional posterior SLNB was performed under ultrasound guidance.

MEASUREMENTS

The primary outcome was the proportion of acceptable intubation condition (AIC), which was analyzed in both per-protocol (PP) and intention-to-treat (ITT) populations. The prespecified non-inferiority margin was -4.8%. Secondary outcomes included intubation success rate on the first attempt, hemodynamic parameters during ATI, time taken for airway anesthesia and intubation, recall of intubation, patient perception of comfort, and incidence and severity of postoperative complications.

MAIN RESULTS

In the PP population, the proportion of AIC in the modified group was 49/49 (100%) and that in the traditional group was 49/49 (100%), absolute difference 0, lower limit of 1-sided 95% CI, -0.3%. In the ITT population, the primary outcomes in the modified and traditional group were 52/52 (100%) and 51/52 (98.1%), respectively, with an absolute difference of 1.9% and a lower limit of 1-sided 95% CI of -1.2%. The non-inferiority of modified ultrasound-guided anterior SLNB was confirmed in both populations.

CONCLUSIONS

Among adults without difficult airways during videolaryngoscope-assisted ATI, the modified ultrasound-guided anterior SLNB, compared to the traditional posterior approach, showed a statistically non-inferior effect in terms of providing AIC.

Prediction of the difficult airway by pre-operative ultrasound-based measurement of airway parameters: A prospective observational study

Background and Aims

Ultrasonography has emerged as a new airway assessment tool. However, its role in predicting difficult airways needs to be explored. This study aimed to evaluate the accuracy of pre-operative ultrasound assessment of the neck in predicting difficult airways in patients undergoing elective surgery under general anaesthesia.

Methods

One hundred and fourteen adult patients undergoing elective surgeries under general anaesthesia were enrolled in this study. In the pre-operative room, upper airway ultrasound measurements of the neck were obtained, namely, distance from skin to the hyoid bone, distance from skin to the thyroid isthmus and thickness of the base of the tongue. Clinical airway assessment details were noted from the pre-anaesthetic evaluation form. The airway management technique was noted. Receiver operating characteristic curves were used to assess the diagnostic value of these upper airway ultrasound measurements in predicting difficult airways.

Results

The distance from the skin to the thyroid isthmus in the difficult airway group (0.37 ± 0.133 cm) was significantly higher than in the non-difficult group (P = 0.007). It appeared to be a better predictor of difficult airways and correlated better with clinical tests among the measured ultrasound parameters. The body mass index was significantly higher in the difficult airway group (P = 0.009).

Conclusion

Considering the difference in means between the two groups, distance from the skin to the thyroid isthmus should be explored as a potential predictor of a difficult airway in studies with a larger sample size.

Left Head Rotation as an Alternative to Difficult Tracheal Intubation: Randomized Open Label Clinical Trial

BACKGROUND

Tracheal intubation is a life-saving intervention, and optimizing the patient's head and neck position for the best glottic view is a crucial step that accelerates the procedure. The left head rotation maneuver has been recently described as an innovative alternative to the traditional sniffing position used for tracheal intubation with marked improvement in glottic visualization.

OBJECTIVE

This study compared the glottic view and intubating conditions in the sniffing position versus left head rotation during direct laryngoscopy.

METHODS

This randomized, open-label clinical trial enrolled 52 adult patients admitted to Baguio General Hospital and Medical Center from September 2020 to January 2021 for an elective surgical procedure requiring tracheal intubation under general anesthesia. Intubation was done using a 45° left head rotation in the experimental group (n=26), while the control group (n=26) was intubated using the conventional sniffing position. Glottic visualization and intubation difficulty with the two procedures were assessed using the Cormack-Lehane grade and Intubation Difficulty Scale, respectively. Successful intubation is measured by observing a capnographic waveform in the end-tidal CO2 monitor after placement of the endotracheal tube.

RESULTS

There was no statistically significant difference in the Cormack-Lehane grade, with 85% (n=44) of patients classified under grades 1 (n=11 and n=15) and 2 (n=11 and n=7) in the left head rotation and sniffing position groups, respectively. In addition, there were no statistically significant differences in the Intubation Difficulty Scale scores of patients intubated with left head rotation or sniffing position; 30.7% (n=8) of patients in both groups were easily intubated, while 53.8% (n=14) in left head rotation and 57.6% (n=15) in sniffing position groups were intubated with slight difficulty. Similarly, there were no significant differences between the 2 techniques in any of the 7 parameters of the Intubation Difficulty Scale, although numerically fewer patients required the application of additional lifting force (n=7, 26.9% vs n=11, 42.3%) or laryngeal pressure (n=3, 11.5% vs n=7, 26.9%) when intubated with left head rotation. The intubation success rate with left head rotation was 92.3% versus 100% in the sniffing position, but this difference was not statistically significant.

CONCLUSIONS

Left head rotation produces comparable laryngeal exposure and intubation ease to the conventional sniffing position. Therefore, left head rotation may be an alternative for patients who cannot be intubated in the sniffing position, especially in hospitals where advanced techniques such as video laryngoscopes and flexible bronchoscopes are unavailable, as is the case in this study. However, since our sample size was small, studies with a larger study population are warranted to establish the generalizability of our findings. In addition, we observed inadequate familiarity among anesthesiologists with the left head rotation technique, and the intubation success rate may improve as practitioners attain greater technical familiarization.

TRIAL REGISTRATION

International Standard Randomised Controlled Trial Number (ISRCTN)ISRCTN23442026; https://www.isrctn.com/ISRCTN23442026.

Challenging Anaesthesia Management of a Patient with Fryns Syndrome: A Case Report

Fryns syndrome cases with variable characteristics require careful preoperative evaluation and have challenges for airway management. Craniofacial anomalies can complicate both ventilation and intubation. Extubation can also be problematic because of limited pulmonary reserves.

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.

The effect of rocuronium priming dose based on actual versus corrected body weight in modified rapid sequence intubation

Background

Rapid sequence intubation (RSI) is a technique that allows patients to be quickly intubated and have the airway secured.

Aims

The purpose of this study was to investigate the effect of rocuronium priming and intubation dose calculated according to actual body weight (ABW) or corrected body weight (CBW) on the neuromuscular block and intubation quality in rapid sequence induction and intubation (RSII).

Patients and Methods

This prospective randomized, double-blind study was conducted on a total of 60 patients randomized into two groups using the closed-envelope method between January 2021 and December 2021, with 30 individuals in each group. In group 1, CBW was used with the formula to calculate the neuromuscular blocking drug (NMBD) dose. The ABW of patients was used to calculate the NMBD dose in group 2.

Results

The data of 50 female patients who underwent group 1 (CBW, n = 25) and group 2 (ABW, n = 25) were analyzed. Age, weight, height, body mass index (BMI), quality of laryngoscopy, post-priming side effects, mean arterial pressure (MAP), and heart rate (HR) values did not differ across the groups. When train-of-four (TOF) values, priming and intubation dose, and laryngoscopy time were compared, a statistically significant difference was found between the two groups of TOF count (TOF C) 1 (the duration of action).

Conclusion

This study suggests that the application of rocuronium priming and intubation dose according to CBW in RSII, especially during the pandemic, provided similar intubation conditions as the application according to ABW, while its shorter duration of action shows that it can be preferred, especially in short-term surgical cases.

Comparison of modified anterior and traditional posterior accesses for ultrasound-guided superior laryngeal nerve block in awake endotracheal intubation: study protocol for a randomised non-inferiority clinical trial

INTRODUCTION

Awake tracheal intubation (ATI) involves placing a tracheal tube in an awake, spontaneously breathing patient. Superior laryngeal nerve block (SLNB) can effectively abolish the glottic closure reflex, and blunt the sensation of the structures above the cords. A method that consists of SLNB along with translaryngeal injection (TLI) can provide satisfactory anaesthesia and intubating conditions. We present a novel modified access of SLNB, ultrasound (US)-guided anterior SLNB, to aid awake videolaryngoscopes-assisted endotracheal intubation in adult elective surgery patients, and we compare the effectiveness and safety to traditional US-guided posterior SLNB.

METHODS AND ANALYSIS

A total of 100 adult elective surgery patients requiring general endotracheal anaesthesia will be randomly assigned to the modified group (modified US-guided anterior SLNB) or the traditional group (traditional US-guided posterior SLNB). After SLNB, all participants will be performed with TLI. The primary outcome is the proportion of acceptable intubation conditions based on intubation scores. Secondary outcomes include: (a) the first-attempt intubation success rate, (b) haemodynamic changes during ATI, (c) time taken for airway anaesthesia and intubation, (d) recall of intubation, (e) participant perception of comfort during intubation, (f) perioperative complication rate. This report describes the study design of this randomised controlled trial.

ETHICS AND DISSEMINATION

The study protocol has been approved by an ethical committee of the West China Hospital (Sichuan University), and registered at the Chinese Clinical Trials Register (www.chictr.org.cn). Results will be published in a peer-reviewed journal.

TRIAL REGISTRATION NUMBER

ChiCTR2200058086.

Deep-learning model associating lateral cervical radiographic features with Cormack-Lehane grade 3 or 4 glottic view

Unanticipated difficult laryngoscopy is associated with serious airway-related complications. We aimed to develop and test a convolutional neural network-based deep-learning model that uses lateral cervical spine radiographs to predict Cormack-Lehane grade 3 or 4 direct laryngoscopy views of the glottis. We analysed the radiographs of 5939 thyroid surgery patients at our hospital, 253 (4%) of whom had grade 3 or 4 glottic views. We used 10 randomly sampled datasets to train a model. We compared the new model with six similar models (VGG, ResNet, Xception, ResNext, DenseNet and SENet). The Brier score (95%CI) of the new model, 0.023 (0.021-0.025), was lower ('better') than the other models: VGG, 0.034 (0.034-0.035); ResNet, 0.033 (0.033-0.035); Xception, 0.032 (0.031-0.033); ResNext, 0.033 (0.032-0.033); DenseNet, 0.030 (0.029-0.032); SENet, 0.031 (0.029-0.032), all p < 0.001. We calculated mean (95%CI) of the new model for: R² , 0.428 (0.388-0.468); mean squared error, 0.023 (0.021-0.025); mean absolute error, 0.048 (0.046-0.049); balanced accuracy, 0.713 (0.684-0.742); and area under the receiver operating characteristic curve, 0.965 (0.962-0.969). Radiographic features around the hyoid bone, pharynx and cervical spine were associated with grade 3 and 4 glottic views.

Prediction of Difficult Laryngoscopy Using Ultrasound: A Systematic Review and Meta-Analysis

OBJECTIVES

Evaluate associations between ultrasound measures and difficult laryngoscopy.

DATA SOURCES

MEDLINE, Embase, Google Scholar, Web of Science, and the Cochrane Library were searched using MeSH terms and keywords.

STUDY SELECTION

Studies published in English describing the use of airway ultrasound for identifying difficult laryngoscopy, with sufficient data to calculate sensitivity and specificity using 2 × 2 tables.

DATA EXTRACTION

We assigned the described indices of airway dimension to one of three domains based on methodology characteristics: anterior tissue thickness domain, anatomical position domain, and oral space domain. We then performed a bivariate random-effects meta-analysis, deriving pooled sensitivity, specificity, diagnostic odds ratio, positive likelihood ratio, and negative likelihood ratio estimates. We assessed risks of bias using Quality Assessment of Diagnostic Accuracy Studies-2 analysis.

DATA SYNTHESIS

Thirty-three studies evaluating 27 unique indices were included in the meta-analysis. The ultrasound protocols of the included studies were heterogeneous. Anterior tissue thickness demonstrated a pooled sensitivity of 76% (95% CI, 71-81%), specificity of 77% (95% CI, 72-81%), and an area under the receiver operating characteristic curve (AUROC) of 0.83 (95% CI, 0.80-0.86). Anatomical position demonstrated a pooled sensitivity of 74% (95% CI, 61-84%), specificity of 86% (95% CI, 78-91%), and an AUROC of 0.87 (95% CI, 0.84-0.90). Oral space demonstrated a pooled sensitivity of 53% (95% CI, 0.36-0.69), specificity of 77% (95% CI, 0.67-0.85), and an AUROC of 0.73 (95% CI, 0.69-0.77).

CONCLUSIONS

Airway ultrasound metrics associate with difficult laryngoscopy in three domains: anterior tissue thickness, anatomic position, and oral space. An assessment instrument combining clinical and ultrasound assessments may be an accurate screening tool for difficult laryngoscopy.

Multivariable prediction models for difficult direct laryngoscopy: Systematic review and literature metasynthesis

CONTEXT

The difficult airway is an important scenario in anaesthesia due to the impact of its potential complications, and the difficulty in predicting its presence in current clinical practice.

METHODS

Systematic review of articles in English and Spanish retrieved from MEDLINE (Ovid), LILACS and EMBASE up to March 2018. The search strategy was defined by the authors. The reviewers uploaded the studies to specially designed tables in order to qualitatively analyse the results of each paper.

RESULTS

A total of 3602 studies were identified. Thirty-four of these were included in the qualitative review. The most commonly used definition of difficulty was the Cormack-Lehane 3 or 4 classification, with a weighted mean incidence of 7.23%. The most relevant finding was the methodological weaknesses in obtaining these scales.

CONCLUSIONS

Available prediction models show limited discrimination, and weaknesses were detected in the methodology used to develop these prediction rules.

Airway Management: Difficulty of Intubation and Range of Movement of the Thyroid Cartilage

PURPOSE

Difficult endotracheal intubation has been associated with a number of anatomic factors. According to our experience, the range of movement of thyroid cartilage can be used as a useful test to determine the difficulty in endotracheal intubation. The aim of this study was to evaluate the association between the range of movement of thyroid cartilage and difficulty in intubation.

DESIGN

Cross-sectional study.

METHODS

This study was carried out on 400 patients at (Shohada Ashayer Hospital, Khorramabad). After obtaining consent letters from the patients who were between 18 and 60 years of age, the patients underwent general anesthesia. The participants were evaluated by Mallampati and other evaluating tests. The range of movement of thyroid cartilage from the midline was measured and recorded.

FINDINGS

There were significant correlation between the range of movement of thyroid cartilage and thyromental distance. In addition, in patients with Cormack-Lehane class 1, the mean range of movement of thyroid cartilage was significantly more than the patients with Cormack-Lehane class 3 and 4.

CONCLUSIONS

The outcomes of our study indicate that the range of movement of thyroid cartilage can be used for predication of difficult intubation. However, further randomized trials should be conducted in this regard.

Airway management in patients with obesity

Airway management in patients with obesity remains a complex and evolving topic that is becoming more pertinent given the increasing prevalence of obesity and bariatric surgery worldwide. Obesity is associated with increased morbidity and mortality secondary to anesthetic complications, especially related to airway management. Preoperative assessment is especially vital for the bariatric patient so that potential predictors for a difficult airway can be identified. There are several airway management strategies and techniques for the bariatric population that may help reduce postoperative pulmonary complications. This review aims to discuss assessment of the airway, ideal patient positioning, intubation techniques and devices, apneic oxygenation, optimal ventilation strategies, and extubation and post-anesthesia care.

Comparison of airway assessment tests for prediction of difficult intubation in obese patients: importance of thyromental height and upper lip bite test

BACKGROUND

Prediction of difficult intubation (DI) has remained challenging for anesthesiologists and validity of airway assessment tests has not been fully investigated. This study aims to compare predictive values of these tests for prediction of DI in obese patients.

METHODS

196 patients with body mass index (BMI) ≥ 30 kg/m2 were included in this prospective study. Variables including intubation difficulty scale (IDS), thyromental height (TMH), hyomental distance (HMD) in extent and neutral neck position, HMD ratio (HMDR), sternomental distance (SMD), thyromental distance (TMD), ratio of height to TMD (RHTMD), width of mouth opening (MO), mandibular length (ML), Cormack-lehane (C-L) grade, upper lip bite test (ULBT), history of snoring, and obstructive sleep apnea were collected. Multiple logistic regression and receiver operating characteristic (ROC) curve analysis were used to determine independent predictors of DI (defined as IDS≥5) and their cut off points.

RESULTS

DI and difficult laryngoscopy (defined as C-L grade ≥3) were observed in 23% and 24.5% of the study population, respectively. Multiple logistic regression identified TMH (Odds ratio (OR):0.28, 95% confidence interval (CI):0.14-0.58, p=0.001), BMI (OR:1.18, 95% CI: 1.11- 1.26, p<0.001), HMDR (OR:0.45, 95% CI:0.36-0.56, p<0.001) and ULBT (OR: 3.91, 95% CI: 2.14-7.14, p<0.001) as independent predictors of DI. Sensitivity of TMH<4.8 cm, BMI>34.9 kg/m2, HMDR<1.4 and ULBT class≥2 were determined as 75.1%, 73.3%,62.3% and 93.3% respectively.

CONCLUSIONS

TMH and ULBT had the highest sensitivity for prediction of DI in obese patients in this study and it is recommended to be considered as part of airway assessment in this patient population.

Head-neck movement may predispose to the development of arytenoid dislocation in the intubated patient: a 5-year retrospective single-center study

Background

Arytenoid dislocation is a rare laryngeal injury that may follow endotracheal intubation. We aimed to determine the incidence and risk factors for arytenoid dislocation after surgery under general anaesthesia.

Methods

We reviewed the medical records of patients who underwent operation under general anaesthesia with endotracheal intubation from January 2014 to December 2018. Patients were divided into the non-dislocation and dislocation groups depending on the presence or absence of arytenoid dislocation. Patient, anaesthetic, and surgical factors associated with arytenoid dislocation were determined using Poisson regression analysis.

Results

Among the 25,538 patients enrolled, 33 (0.13%) had arytenoid dislocation, with higher incidence after anterior neck and brain surgery. Patients in the dislocation group were younger (52.6 ± 14.4 vs 58.2 ± 14.2 yrs, P = 0.025), more likely to be female (78.8 vs 56.5%, P = 0.014), and more likely to be intubated by a first-year anaesthesia resident (33.3 vs 18.5%, P = 0.048) compared to those in the non-dislocation group. Patient positions during surgery were significantly different between the groups (P = 0.000). Multivariable Poisson regression identified head-neck positioning (incidence rate ratio [IRR], 3.10; 95% confidence interval [CI], 1.50–6.25, P = 0.002), endotracheal intubation by a first-year anaesthesia resident (IRR, 2.30; 95% CI, 1.07–4.64, P = 0.024), and female (IRR, 3.05; 95% CI, 1.38–7.73, P = 0.010) as risk factors for arytenoid dislocation.

Conclusion

This study showed that the incidence of arytenoid dislocation was 0.13%, and that head-neck positioning during surgery, less anaesthetist experience, and female were significantly associated with arytenoid dislocation in patients who underwent surgeries under general anaesthesia with endotracheal intubation.

Multivariable prediction models for difficult direct laryngoscopy: Systematic review and literature metasynthesis

CONTEXT

The difficult airway is an important scenario in anaesthesia due to the impact of its potential complications, and the difficulty in predicting its presence in current clinical practice.

METHODS

Systematic review of articles in English and Spanish retrieved from MEDLINE (Ovid), LILACS and Embase up to March 2018. The search strategy was defined by the authors. The reviewers uploaded the studies to specially designed tables in order to qualitatively analyse the results of each paper.

RESULTS

A total of 3602 studies were identified. Thirty-four of these were included in the qualitative review. The most commonly used definition of difficulty was the Cormack-Lehane3 or 4 classification, with a weighted mean incidence of 7.23%. The most relevant finding was the methodological weaknesses in obtaining these scales.

CONCLUSIONS

Available prediction models show limited discrimination, and weaknesses were detected in the methodology used to develop these prediction rules.

Useful Ultrasonographic Parameters to Predict Difficult Laryngoscopy and Difficult Tracheal Intubation-A Systematic Review and Meta-Analysis

Unexpected difficult airway management can cause significant morbidity and mortality in patients admitted for elective procedures. Ultrasonography is a promising tool for perioperative airway assessment, nevertheless it is still unclear which sonographic parameters are useful predictors of difficult laryngoscopy and tracheal intubation. To determine the ultrasonographic predictors of a difficult airway that could be applied for routine practice, a systematic review and meta-analysis was conducted. Literature search was performed on PubMED, Web of Science and Embase using the selected keywords. Human primary studies, published in English with the use of ultrasonography to prediction of difficult laryngoscopy or tracheal intubation were included. A total of 19 articles (4,570 patients) were analyzed for the systematic review and 12 articles (1,141 patients) for the meta-analysis. Standardized mean differences between easy and difficult laryngoscopy groups were calculated and the parameter effect size quantified. A PRISMA methodology was used and the critical appraisal tool from Joanna Briggs Institute was applied. Twenty-six sonographic parameters were studied. The overall effect of the distance from skin to hyoid bone (p = 0.02); skin to epiglottis (p = 0.02); skin to the anterior commissure of vocal cords (p = 0.02), pre-epiglottis space to distance between epiglottis and midpoint between vocal cords (p = 0.01), hyomental distance in neutral (p < 0.0001), and extended (p = 0.0002) positions and ratio of hyomental distance in neutral to extended (p = 0.001) was significant. This study shows that hyomental distance in the neutral position is the most reliable parameter for pre-operative airway ultrasound assessment. The main limitations of the study are the small sample size, heterogeneity of studies, and absence of a standardized ultrasonographic evaluation method [Registered at International prospective register of systematic reviews (PROSPERO): number 167931].

Factors and Economic Outcomes Associated with Documented Difficult Intubation in the United States

Purpose

Establishing good mechanical ventilation is a critical component and prerequisite to a wide range of surgical and medical interventions. Yet difficulties in intubating patients, and a variety of associated complications, are well documented. The economic burden resulting from difficult intubation (DI), however, is not well understood. The current study examines the economic burden of documented DI during inpatient surgical admissions and explores factors that are associated with DI.

Patients and Methods

Using data from the Premier Healthcare Database, adult patients with inpatient surgical admissions between January 1, 2016 and December 31, 2018 were selected. International Classification of Diseases, Tenth Edition, Clinical Modification (ICD-10-CM) diagnosis codes were used to classify the patients into matched cohorts of DI and non-DI patients.

Results

Patients in the DI group have mean inpatient costs and intensive care unit (ICU) costs that are substantially higher than patients without difficult intubations ($14,468 and $4,029 higher, respectively). Mean hospital length of stay and ICU length of stay were 3.8 days and 2.0 days longer, respectively (all p<0.0001, except ICU cost p=0.0001) in the DI group. Obesity, other chronic conditions, and larger hospital size were significantly associated with DI.

Conclusion

DI is associated with higher average cost and longer average length of stay.

McGrath Video Laryngoscope Versus Macintosh Direct Laryngoscopy for Intubation of Morbidly Obese Patients: A Randomized Trial

BACKGROUND

Two-thirds of the US population is considered obese and about 8% morbidly obese. Obese patients may present a unique challenge to anesthesia clinicians in airway management. Videolaryngoscopes may provide better airway visualization, which theoretically improves intubation success. However, previous work in morbidly obese patients was limited. We therefore tested the primary hypothesis that the use of McGrath video laryngoscope improves visualization of the vocal cords versus Macintosh direct laryngoscopy (Teleflex, Morrisville, NC) in morbidly obese patients.

METHODS

We enrolled 130 surgical patients, aged 18-99 years, with a body mass index ≥40 kg/m and American Society of Anaesthesiologists (ASA) physical status I-III. Patients were randomly allocated 1:1-stratified for patient's body mass index ≥50 kg/m-to McGrath video laryngoscope versus direct laryngoscopy with a Macintosh blade. The study groups were compared on glottis visualization, defined as improved Cormack and Lehane classification, with proportional odds logistic regression model.

RESULTS

McGrath video laryngoscope provided significantly better glottis visualization than Macintosh direct laryngoscopy with an estimated odds ratio of 4.6 (95% confidence interval [CI], 2.2-9.8; P < .01). We did not observe any evidence that number of intubation attempts and failed intubations increased or decreased.

CONCLUSIONS

McGrath video laryngoscope improves glottis visualization versus Macintosh direct laryngoscopy in morbidly obese patients. Large clinical trials are needed to determine whether improved airway visualization with videolaryngoscopy reduces intubation attempts and failures.

COVID-19 disease: invasive ventilation

This article focuses on the critical care nurse's role in the management of patients with COVID-19 who require invasive ventilation in order to improve outcomes and prevent complications. The nature of COVID-19 is such that many patients deteriorate rapidly and for members of this group requiring intubation and invasive ventilation, different approaches to airway management and ventilatory support are required. In order to reduce the risk of complications and an overview of invasive ventilation, including commonly used modes, potential complications, nursing care, weaning and extubation are all described. COVID-19 presents several challenges as the disease progresses, hypoxemia may worsen, and the patient can develop Acute Respiratory Distress Syndrome. Therefore, additional treatment strategies including the use of the prone position and the use of nitric oxide and prostacyclin nebulisers have been included. The strategies presented in this article are relevant to both critical care nurses and those re-deployed to intensive care units where nurses will inevitably be involved in the management of patients requiring invasive ventilation. Weaning these patients off invasive ventilation is multi-factorial and may be short or long term. A multi-disciplinary weaning plan, the principles, stages/phases, and speed of weaning with expected parameters prior extubation are explained. Planned and unplanned extubation with the serious complications of the latter as the patient may not be ready and may require emergency re-intubation resulting in setbacks should be avoided.

The knowledge of Cormack-Lehane intubation grade and intensive care unit outcome

Background

For patients on invasive mechanical ventilation (MV), it is unclear if knowledge of intubation grade influences intensive care unit (ICU) outcome. We aimed to determine if there was an independent relationship between knowledge of intubation grade during ICU admission and in-hospital mortality.

Methods

We performed a retrospective cohort study of all patients receiving invasive MV at the Alfred ICU between December 2011 and February 2015. Demographics, details of admission, the severity of illness, chronic health status, airway detail (unknown or known Cormack-Lehane (CL) grade), MV duration and in-hospital mortality data were collected. Univariable and multivariable analyses were conducted to assess the relationship. The primary outcome was in-hospital mortality, and the secondary outcome was the duration of MV.

Results

Amongst 3556 patients studied, 611 (17.2%) had an unknown CL grade. Unadjusted mortality was higher in patients with unknown CL grade compared to known CL grade patients (21.6% vs. 9.9%). After adjusting for age, sex, severity of illness, type of ICU admission, cardiac arrest, limitations to treatment and diagnosis, having an unknown CL grade during invasive MV was independently associated with an increase in mortality (adjusted OR 1.5, 95% CI 1.14-1.98, p < 0.01).

Conclusion

Amongst ICU patients receiving MV, not knowing CL grade appears to be independently associated with increased mortality. This information should be communicated and documented in all patients receiving MV in ICU.

A prospective randomized comparison of airway seal using the novel vision-guided insertion of LMA-Supreme® and LMA-Protector®

The laryngeal mask airways supreme (LMA-Supreme™) and protector (LMA-Protector™) are generally placed blindly, often resulting in a less than optimal position and vision-guided placement has been recommended. This prospective, randomized controlled study compared the efficacy of airway seal by measuring the oropharyngeal leak pressure in 100 surgical patients who underwent a variety of non-thoracic surgery under general anaesthesia, suitable with a supraglottic airway device. Patients were allocated to either the LMA-Supreme (n = 50) or LMA-Protector (n = 50) group. All insertions were performed under vision of a videolaryngoscope using an 'insert-detect-correct-as-you-go' technique with standardized corrective measures. Our primary endpoint, mean oropharyngeal leak pressure, was significantly higher in the LMA-Protector (31.7 ± 2.9 cm H₂O) compared to the LMA-Supreme (27.7 ± 3.5 cm H₂O) group (mean difference 4.0 cm H₂O, 95% confidence interval (CI) 2.7-5.3 cm H₂O, p < 0.001) after achieving a near-optimal fibreoptic position in the LMA-Protector (94%) and LMA-Supreme (96%) groups. No statistically significant differences were shown for secondary outcomes of alignment, number of insertion attempts and malpositions, and final anatomical position as scored by fibreoptic evaluation. Corrective manoeuvres were required in virtually all patients to obtain a correct anatomically positioned LMA. Position outcomes of the two devices were similar except for the proportion of procedures with folds in the proximal cuff (90% LMA-Supreme vs. 2% LMA-Protector, p < 0.001), the need for intracuff pressure adjustments (80% LMA-Supreme vs. 48% LMA-Protector, p = 0.001) and size correction (18% LMA-Supreme vs. 4% LMA-Protector, p = 0.025). In conclusion, a higher oropharyngeal leak pressure can be achieved with LMA-Protector compared to LMA-Supreme with optimal anatomical position when insertion is vision-guided.

A Cost-Effectiveness Analysis Comparing the VivaSight Double-Lumen Tube and a Conventional Double-Lumen Tube in Adult Patients Undergoing Thoracic Surgery Involving One-Lung Ventilation

BACKGROUND

One-lung ventilation (OLV) procedures are essential for most thoracic surgeries, and the most common method is intubation with a conventional double-lumen tube (cDLT) and bronchoscopy to verify correct tube placement.

OBJECTIVE

The objective of this study was to conduct a cost-effectiveness analysis comparing the VivaSight double-lumen tube (DL) and a cDLT for OLV procedures.

METHODS

A cost-effectiveness analysis was conducted from a healthcare sector perspective in Denmark using a decision analytic model to assess the potential effects and costs of using VivaSight-DL as an alternative to a cDLT with a reusable bronchoscope. Costs were determined using a micro-costing approach. The effectiveness measure was the number of times that fiberoptic confirmation of the tube placement during intubation or surgery was unnecessary and thus avoided. The effectiveness input was from a randomized controlled trial (n = 52). Both deterministic and probabilistic sensitivity analyses were conducted to assess the robustness of the results.

RESULTS

Fiberoptic confirmation of tube placement was only necessary in two (6.66%) procedures using VivaSight-DL. The cost of using VivaSight-DL was $US299.96 per procedure versus $US347.61 for a cDLT with a reusable bronchoscope. The incremental cost-effectiveness ratio was - $US51.06 per bronchoscopy avoided. The base-case analysis indicated that the use of VivaSight-DL was cost effective compared with the use of a cDLT with reusable bronchoscope. Sensitivity analyses showed that the results were robust and that VivaSight-DL was more effective and less costly.

CONCLUSION

This study suggests that VivaSight-DL is associated with cost savings and reductions in bronchoscope use to verify correct tube placement. The conclusion is based on the results from a single institution. To clarify whether VivaSight-DL is cost effective in larger or global clinical settings, further economic evaluations should be performed.

Accuracy of thyromental height test for predicting difficult intubation in elderly

BACKGROUND

Studies of the accuracy of different airway tests are lacking in elderly. We evaluated and compared the accuracy of thyromental height in predicting difficult intubation in relation to the other traditional airway tests in elderly.

METHODS

We included 120 patients aged ≥ 65 years scheduled for general anesthesia with tracheal intubation. Thyromental height, modified Mallampati test, thyromental distance and sternomental distance were evaluated. Cormack-Lehane grade > 2 was considered difficult laryngoscopy. Difficult tracheal intubation was considered if successful intubation required more than 2 attempts. The accuracy of different tests in predicting difficult intubation and difficult laryngoscopy were evaluated through area under receiver operating characteristic (AUROC) curves. Univariate and multivariate analyses were conducted to identify risk factors for difficult intubation and difficult laryngoscopy.

RESULTS

Our cohort had a mean age of 71(7) years. We encountered difficult laryngoscopy in 15/120 (12%) patients, difficult intubation in 20/120 (17%) patients, and failed laryngoscopy requiring alternative methods for securing the airway in 3/120 (3%) patients. For predicting difficult intubation, thyromental height and modified Mallampati test showed the highest accuracy AUROC (95% confidence interval): 0.9 (0.83-0.95), cut-off value ≤ 5.9 cm, and AUROC (95% confidence interval): 0.89 (0.82-0.94), cut-off value > 2, respectively. Low thyromental height and high modified Mallampati test were the only independent risk factors for difficult laryngoscopy and difficult intubation.

CONCLUSION

In elderly scheduled for elective procedure, both thyromental height and modified Mallampati tests showed good accuracy in predicting difficult intubation and difficult laryngoscopy, whilst thyromental distance and sternomental distance were poor predictors.

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.

Comparison of a Novel Cadaver Model (Fix for Life) With the Formalin-Fixed Cadaver and Manikin Model for Suitability and Realism in Airway Management Training

BACKGROUND

Manikins are widely used in airway management training; however, simulation of realism and interpatient variability remains a challenge. We investigated whether cadavers embalmed with the novel Fix for Life (F4L) embalmment method are a suitable and realistic model for teaching 3 basic airway skills: facemask ventilation, tracheal intubation, and laryngeal mask insertion compared to a manikin (SimMan 3G) and formalin-fixed cadavers.

METHODS

Thirty anesthesiologists and experienced residents ("operators") were instructed to perform the 3 airway techniques in 10 F4L, 10 formalin-fixed cadavers, and 1 manikin. The order of the model type was randomized per operator. Primary outcomes were the operators' ranking of each model type as a teaching model (total rank), ranking of the model types per technique, and an operator's average verbal rating score for suitability and realism of learning the technique on the model. Secondary outcomes were the percentages of successfully performed procedures per technique and per model (success rates in completing the respective airway maneuvers). For each of the airway techniques, the Friedman analysis of variance was used to compare the 3 models on mean operator ranking and mean verbal rating scores.

RESULTS

Twenty-seven of 30 operators (90%) performed all airway techniques on all of the available models, whereas 3 operators performed the majority but not all of the airway maneuvers on all models for logistical reasons. The total number of attempts for each technique was 30 on the manikin, 292 in the F4L, and 282 on the formalin-fixed cadavers. The operators' median total ranking of each model type as a teaching model was 1 for F4L, 2 for the manikin and, 3 for the formalin-fixed cadavers (P < .001). F4L was considered the best model for mask ventilation (P = .029) and had a higher mean verbal rating score for realism in laryngeal mask airway insertion (P = .043). The F4L and manikin did not differ significantly in other scores for suitability and realism. The formalin-fixed cadaver was ranked last and received lowest scores in all procedures (all P < .001). Success rates of the procedures were highest in the manikin.

CONCLUSIONS

F4L cadavers were ranked highest for mask ventilation and were considered the most realistic model for training laryngeal mask insertion. Formalin-fixed cadavers are inappropriate for airway management training.

Anterior neck soft tissue thickness for airway evaluation measured by MRI in patients with cervical spondylosis: prospective cohort study

OBJECTIVES

Anterior neck soft tissue thickness, usually measured by ultrasound, is increasingly being investigated to predict difficult laryngoscopy, but the results have not been validated. Considering the conflicting measurement data, different measuring body positions and lack of a standard ultrasound procedure, we used MRI to verify the efficacy of these popular ultrasonographic parameters.

DESIGN

Prospective cohort study.

SETTING

A tertiary hospital in Beijing, China.

METHODS

We enrolled 315 adult patients who underwent cervical spinal surgery in Peking University Third Hospital from April to October 2016. We analysed MRI data to predict difficult laryngoscopy. Cormack-Lehane scales were assessed during intubation, and patients with a class III or IV view were assigned to the difficult laryngoscopy group.

RESULTS

Univariate analysis showed that male sex (p<0.01), older age (p=0.03) and body weight (p=0.02) were associated with difficult laryngoscopy. MRI data consisted of five common ultrasonographic variables used to predict difficult laryngoscopy, but none was a valuable predictor: skin to hyoid (p=0.18), skin to midpoint of epiglottis (p=0.72), skin to thyroid cartilage at the level of the vocal cords (p=0.10), skin to vocal cords (p=0.44) or skin to anterior to the trachea at the level of suprasternal notch (p=0.92). Adjusted by sex, age and body weight, none of the five MRI indicators had predictive value (p>0.05).

CONCLUSION

The five most commonly studied ultrasonographic indicators of anterior soft tissue thickness appeared unreliable to predict difficult laryngoscopy in patients with cervical spondylosis. Further study is needed to validate the most valuable indicator to predict difficult laryngoscopy.

TRIAL REGISTRATION NUMBER

ChiCTRROC-16008598; Pre-results.

Tracheal intubation with the rigid tube for laryngoscopy - a new method

Background

The rigid tube for laryngoscopy is an instrument used in ENT, for inspecting the larynx and its vicinity. We used it to facilitate intubation, in ENT patients.

Methods

Twenty patients attending for surgery were included for study. Group 1 (n=10) had no airway pathology but at least two predictors of an anatomically difficult airway. Group 2 (n=10) had an obstructing airway pathology. After anesthesia induction, classical laryngoscopy was performed, and intubation grade registered. Using the retromolar approach the rigid tube advanced slowly, the epiglottis was lifted, and the vocal cords were visualized. The bougie was introduced through the rigid tube into the trachea, the rigid tube was extracted, and the intubating tube was placed in the trachea, over the bougie.

Results

The mean (SD) maneuver duration was 59.4 (18.2) sec. The Cormack-Lehane view of the glottis at classical laryngoscopy was poor in four patients in Group 1 and six patients in Group 2. The lowest desaturation was 82%. No complications other than sore throat were noted.

Conclusion

The rigid tube for laryngoscopy is a useful tool for intubation in ENT patients. We noticed an advantage against classical intubation in patients with base of tongue carcinoma, reduced mouth opening and protruding upper incisors with this instrument.

Comparison of Tracheal Intubation Conditions in Operating Room and Intensive Care Unit: A Prospective, Observational Study

WHAT WE ALREADY KNOW ABOUT THIS TOPIC

WHAT THIS ARTICLE TELLS US THAT IS NEW: BACKGROUND:: Tracheal intubation is a common intervention in the operating room and in the intensive care unit. The authors hypothesized that tracheal intubation using direct laryngoscopy would be associated with worse intubation conditions and more complications in the intensive care unit compared with the operating room.

METHODS

The authors prospectively evaluated during 33 months patients who were tracheally intubated with direct laryngoscopy in the operating room, and subsequently in the intensive care unit (within a 1-month time frame). The primary outcome was to compare the difference in glottic visualization using the modified Cormack-Lehane grade between intubations performed on the same patient in an intensive care unit and previously in an operating room. Secondary outcomes were to compare first-time success rate, technical difficulty (number of attempts, operator-reported difficulty, need for adjuncts), and the incidence of complications.

RESULTS

A total of 208 patients met inclusion criteria. Tracheal intubations in the intensive care unit were associated with worse glottic visualization (Cormack-Lehane grade I/IIa/IIb/III/IV: 116/24/47/19/2) compared with the operating room (Cormack-Lehane grade I/IIa/IIb/III/IV: 159/21/16/12/0; P < 0.001). First-time intubation success rate was lower in the intensive care unit (185/208; 89%) compared with the operating room (201/208; 97%; P = 0.002). Tracheal intubations in the intensive care unit had an increased incidence of moderate and difficult intubation (33/208 [16%] vs. 18/208 [9%]; P < 0.001), and need for adjuncts to direct laryngoscopy (40/208 [19%] vs. 21/208 [10%]; P = 0.002), compared with the operating room. Complications were more common during tracheal intubations in the intensive care unit (76/208; 37%) compared with the operating room (13/208; 6%; P < 0.001).

CONCLUSIONS

Compared with the operating room, tracheal intubations in the intensive care unit were associated with worse intubation conditions and an increase of complications.

Analysis of unsuccessful intubations in neonates using videolaryngoscopy recordings

OBJECTIVES

Neonatal intubation is a difficult skill to learn and teach. If an attempt is unsuccessful, the intubator and instructor often cannot explain why. This study aims to review videolaryngoscopy recordings of unsuccessful intubations and explain the reasons why attempts were not successful.

STUDY DESIGN

This is a descriptive study examining videolaryngoscopy recordings obtained from a randomised controlled trial that evaluated if neonatal intubation success rates of inexperienced trainees were superior if they used a videolaryngoscope compared with a laryngoscope. All recorded unsuccessful intubations were included and reviewed independently by two reviewers blinded to study group. Their assessment was correlated with the intubator's perception as reported in a postintubation questionnaire. The Cormack-Lehane classification system was used for objective assessment of laryngeal view.

RESULTS

Recordings and questionnaires from 45 unsuccessful intubations were included (15 intervention and 30 control). The most common reasons for an unsuccessful attempt were oesophageal intubation and failure to recognise the anatomy. In 36 (80%) of intubations, an intubatable view was achieved but was then either lost, not recognised or there was an apparent inability to correctly direct the endotracheal tube. Suctioning was commonly performed but rarely improved the view.

CONCLUSIONS

Lack of intubation success was most commonly due to failure to recognise midline anatomical structures. Trainees need to be taught to recognise the uvula and epiglottis and use these landmarks to guide intubation. Excessive secretions are rarely a factor in elective and premedicated intubations, and routine suctioning should be discouraged. Better blade design may make it easier to direct the tube through the vocal cords.