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.

Effects of avoidance versus use of neuromuscular blocking agents for facilitation of tracheal intubation in children and infants: a protocol for a systematic review, meta-analysis and trial sequential analysis.

BACKGROUND: The European Society of Anesthesiology and Intensive Care recommends the use of neuromuscular blocking agents (NMBA) in adults, to facilitate tracheal intubation and reduce its associated complications. Children who undergo tracheal intubation may suffer some of the same complications, however, no consensus exists regarding the use of NMBA for tracheal intubation in the pediatric population. We will explore the existing evidence assessing the effects of avoidance versus the use of NMBA for the facilitation of tracheal intubation in children and infants. METHODS: This protocol follows the preferred reporting items for systematic reviews and meta-analyses protocols recommendations. We will include all randomized controlled clinical trials assessing the effects of avoidance versus the use of NMBA for facilitation of tracheal intubation (oral or nasal) using direct laryngoscopy or video laryngoscopy in pediatric participants (<18 years). Our primary outcome is incidence of difficult tracheal intubation. Secondary outcomes include incidence of serious adverse events, failed intubation, events of upper airway discomfort or injury, and difficult laryngoscopy. We will conduct a thorough database search to identify relevant trials, including CENTRAL, MEDLINE, EMBASE, BIOSIS, Web of Science, CINAHL, and trial registries. Two review authors will independently handle the screening of literature and data extraction. Each trial will be evaluated for major sources of bias with the "classic risk of bias tool" used in the Cochrane Collaboration tool from 2011. We will use Review manager (RevMan) or R with the meta package to perform the meta-analysis. We will perform a trial sequential analysis on the meta-analysis of our primary outcome, providing an estimate of statistical reliability. Two review authors will independently assess the quality of the body of evidence using the grading of recommendations assessment, development, and evaluation (GRADE) approach. We will use GRADEpro software to conduct the GRADE assessments and to create "Summary of the findings" tables.

Deep learning-based facial analysis for predicting difficult videolaryngoscopy: a feasibility study.

While videolaryngoscopy has resulted in better overall success rates of tracheal intubation, airway assessment is still an important prerequisite for safe airway management. This study aimed to create an artificial intelligence model to identify difficult videolaryngoscopy using a neural network. Baseline characteristics, medical history, bedside examination and seven facial images were included as predictor variables. ResNet-18 was introduced to recognise images and extract features. Different machine learning algorithms were utilised to develop predictive models. A videolaryngoscopy view of Cormack-Lehane grade of 1 or 2 was classified as 'non-difficult', while grade 3 or 4 was classified as 'difficult'. A total of 5849 patients were included, of whom 5335 had non-difficult and 514 had difficult videolaryngoscopy. The facial model (only including facial images) using the Light Gradient Boosting Machine algorithm showed the highest area under the curve (95%CI) of 0.779 (0.733-0.825) with a sensitivity (95%CI) of 0.757 (0.650-0.845) and specificity (95%CI) of 0.721 (0.626-0.794) in the test set. Compared with bedside examination and multivariate scores (El-Ganzouri and Wilson), the facial model had significantly higher predictive performance (p < 0.001). Artificial intelligence-based facial analysis is a feasible technique for predicting difficulty during videolaryngoscopy, and the model developed using neural networks has higher predictive performance than traditional methods.

Determinants of difficult laryngoscopy based on upper airway indicators: a prospective observational study.

BACKGROUND: The main cause of anesthesia-related deaths is the failure to manage difficult airways. Difficult laryngoscopic exposure is a major cause of unsuccessful management of difficult airways. Inadequate preoperative airway assessment hinders the clinical management of difficult airways cases, emphasizing the critical need for accurate identification of difficult airways. Currently, no definitive and reliable indicators are available to predict a difficult airway. Our study aims to predict laryngoscope exposure risk factors by combining ultrasonically measured upper airway anatomic parameters with physical examination indicators. METHODS: Patients aged 18 to 75 years, classified as American Standards Association (ASA) I-III, and scheduled for elective general anesthesia with endotracheal intubation were included. All patients received the upper airway and ultrasonographic measurements. After anesthesia induction, laryngoscope exposure was analyzed using the Cormack-Lehane grading system, with Grades III and IV as indicative of difficult laryngoscopy. Univariate and multivariate logistic regression analyses were performed to identify reliable indicators for predicting difficult laryngoscopy. Receiver Operating Characteristic (ROC) curve analysis was utilized to assess the predictive performance of each indicator. RESULTS: A total of 1120 patients finished the study, with 710 cases found in Grade I laryngoscopic exposure group, 360 cases in Grade II group, and 50 cases in Grade III group. There was no case observed in Grade IV group, thereby resulting in an incidence of difficult laryngoscopy of 4.46%. Univariate logistic regression analysis revealed that several parameters including age, Body Mass Index (BMI), neck circumference, neck mobility, snoring intensity, as well as ultrasound measurements of the pre-epiglottic space and thyromental distance were identified as significant risk factors for difficult laryngoscopy (P < 0.05). Among these, BMI, and neck circumference exhibited notable predictive value, with Area Under The Curve (AUC) values of 0.746 (95%CI 0.649-0.842) and 0.732 (95%CI 0.638-0.827), respectively. Neck mobility was also identified as an independent risk factor for predicting difficult laryngoscopy (P = 0.009) in multivariate logistic regression analysis, with an AUC of 0.672 (0.562-0.782) in the ROC curve. CONCLUSIONS: Our findings revealed a direct correlation between difficult laryngoscopy and age, BMI, neck circumference, neck mobility, snoring intensity, as well as ultrasound measurements of the pre-epiglottic space and thyromental distance. Furthermore, neck mobility was identified as an independent predictive factor. TRIAL REGISTRATION: The trial was registered prior to patient enrollment at clinicaltrials.gov (register no. ChiCTR2100053826, Date of registration: November 30, 2021).

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.

Development and Internal Validation of a Prediction Model for Difficult Laryngoscopy Using Ultrasound-Derived Factor in Comatose Patients.

OBJECTIVES: The distance from skin to the hyoid bone (DSHB) and skin to the anterior commissure of vocal cords (DSAC) are reliable parameters for pre-operative airway ultrasound assessment in awake patients and can be assessed in comatose patients. This study aimed to inspect its feasibility and accuracy in predicting difficult laryngoscopy for comatose patients. METHODS: A prospective cohort study included patients with a Glasgow Coma Scale (GCS) of ≤8 who underwent emergency tracheal intubation between November 2019 and August 2020. The outcome was difficult laryngoscopy and classified according to the Cormack-Lehane grading. RESULTS: A total of 151 patients were included in the study. Fifty-two (34.4%) patients were categorized as having difficult laryngoscopy. The DSHB add DSAC (hereinafter referred to as the "DSBAC") was superior to either parameter alone in the predictive performance, and the optimal cut-off value was 1.90. To optimize the predictive value, DSBAC (adjusted odds ratio [OR]: 7.76; 95% confidence interval [CI]: 2.88-20.94; P < .001), GCS (adjusted OR: 1.39; 95% CI: 3.93-26.28; P = .039), mandibular retraction (adjusted OR: 8.20; 95% CI: 1.92-35.09; P = .005) and edentulous (adjusted OR: 4.23; 95% CI: 1.40-12.80; P = .011) were included in a multivariable model and constructed a nomogram. Discrimination and calibration statistics were satisfactory, with C-index above 0.80 from both model development and internal validation. CONCLUSIONS: Ultrasound-derived factor, DSBAC, can be easily assessed and help predict difficult laryngoscopy among comatose patients. A simple nomogram including only four clinical items exhibited excellent discrimination performance and was useful when comatose patients underwent emergency tracheal intubation.

A quantitative study of airway ultrasound in predicting difficult laryngoscopy: A prospective study.

PURPOSE: As common clinical screening tests cannot effectively predict a difficult airway, and unanticipated difficult laryngoscopy remains a challenge for physicians. We herein used ultrasound to develop some point-of-care predictors for difficult laryngoscopy. METHODS: This prospective observational study included 502 patients who underwent laryngoscopy and a detailed sonographic assessment. Patients under 18 years old, or with maxillofacial deformities or fractures, limited mouth opening, limited neck movement or history of neck surgery were excluded from the study. Laryngoscopic views of all patients were scored and grouping using the modified Cormack-Lehane (CL) scoring system. The measurements acquired comprised tongue width, the longitudinal cross-sectional area of the tongue, tongue volume, the mandible-hyoid bone distance, the hyoid bone-glottis distance, the mandible-hyoid bone-glottis angle, the skin-thyrohyoid membrane distance, the glottis-superior edge of the thyroid cartilage distance (DGTC), the skin-hyoid bone distance, and the epiglottis midway-skin distance. ANOVA and Chi-square were used to compare differences between groups. Logistic regression was used to identify risk factors for difficult laryngoscopy and it was visualized by receiver operating characteristic curves and nomogram. R version 3.6.3 and SPSS version 26.0 were used for statistical analyses. RESULTS: Difficult laryngoscopy was indicated in 49 patients (CL grade Ⅲ - Ⅳ) and easy laryngoscopy in 453 patients (CL grade Ⅰ - Ⅱ). The ultrasound-measured mandible-hyoid bone-glottis angle and DGTC significantly differed between the 2 groups (p < 0.001). Difficult laryngoscopy was predicted by an area under the curve (AUC) of 0.930 with a threshold mandible-hyoid bone-glottis angle of 125.5° and by an AUC of 0.722 with a threshold DGTC of 1.22 cm. The longitudinal cross-sectional area of the tongue, tongue width, tongue volume, the mandible-hyoid distance, and the hyoid-glottis distance did not significantly differ between the groups. CONCLUSION: Difficult laryngoscopy may be anticipated in patients in whom the mandible-hyoid bone-glottis angle is smaller than 125.5° or DGTC is larger than 1.22 cm.

Comparison of the patients with diabetes mellitus using either insulin or oral antidiabetic drug in terms of difficult laryngoscopy: A randomized controlled study.

Aim: We aimed to evaluate the differences in the difficult laryngoscopy as a general anesthetic component in patients with Diabetes Mellitus (DM) using either insulin or oral antidiabetic drug (OADD). Materials and Methods: This study was planned for a total of 230 patients including DM patients and non-DM patients as a control group who would undergo elective surgery between 30.01.2020-30.04.2020. Age, gender, body mass index (BMI), Mallampati scores, thyromental distance (TMD), inter-incisor distance (IID), and neck extension measurements were noted. Preoperative HbA1C levels, DM type, diagnosis time, and duration of insulin or OADD use were recorded. Patients without DM (Group C), patients using insulin (Group I), and patients using OADD (Group D) were separated respectively. Cormack-Lehane (CL) classification of the airway, number of laryngoscopic attempts, intubation success at the first attempt, intubation duration, performance of backward-upward-rightward pressure (BURP) maneuver, and requirement of use of different airway equipment were compared between the groups. Results: The data of 192 patients were compared. The mean IID (mm) was lower in Groups I and D than C. It was the lowest in Group I. Presence of neck extension of more than 30° in Groups I and D was lower than C. Classification of CL in Groups I and D was higher than C. Number of laryngoscopic attempts was higher in Groups I and D than C. Intubation success at the first attempt was lower in Groups I and D than C. The intubation duration was longer in Groups I and D than C. It was the longest in Group I. The more BURP maneuvering was required in Groups I and D than C. In Groups I and D, the number of uses of different airway equipment was higher than in Group C. The rate of using a videolaryngoscope (VL) in Group I was higher than in Groups D and C. Conclusion: Difficult laryngoscopy was more common in DM patients. Moreover, in patients with DM using insulin, VL use was more often and intubation duration was longer than in patients with DM using OADD.

Predicting difficult laryngoscopy in morbidly obese Thai patients by ultrasound measurement of distance from skin to epiglottis: a prospective observational study.

BACKGROUND: In morbidly obese patients, airway management is challenging since the incidence of difficult intubation is three times than those with a BMI within the healthy range. Standard preoperative airway evaluation may help to predict difficult laryngoscopy. Recent studies have used ultrasonography-measured distance from skin to epiglottis and pretracheal soft tissue at the level of vocal cords, and cut-off points of 27.5 mm and 28 mm respectively have been proposed to predict difficult laryngoscopy. The purpose of this study is to evaluate ultrasonography-measured distance from skin to epiglottis for predicting difficult laryngoscopy in morbidly obese Thai patients. METHODS: This prospective observational study was approved by the Ethics Committee of the Faculty of Medicine, Prince of Songkla University. Data were collected from January 2018 to August 2020. Eighty-eight morbidly obese patients (BMI ≥ 35 kg/m2) requiring general anesthesia with endotracheal intubation for elective surgery were enrolled in the Songklanagarind Hospital. Preoperatively, anesthesiologists or nurse anesthetists who were not involved with intubation evaluated and recorded measurements (body mass index, neck circumference, inter incisor distance, sternomental distance, thyromental distance, modified Mallampati scoring, upper lip bite test, and distance from skin to epiglottis by ultrasound. The laryngoscopic view was graded on the Cormack and Lehane scale. RESULTS: Mean BMI of the eighty-eight patients was 45.3 ± 7.6 kg/m2. The incidence of difficult laryngoscopy was 14.8%. Univariate analysis for difficult laryngoscopy indicated differences in thyromental distance, sternomental distance and the distance from skin to epiglottis by ultrasonography. The median (IQR) of thyromental distance in difficult laryngoscopy was 6.5 (6.3, 8.0) cm compared with 7.5(7.0, 8.0) cm in easy laryngoscopy (p-value 0.03). The median (IQR) of sternomental distance in difficult laryngoscopy was 16.8 (15.2, 18.0) cm compared with 16.0 (14.5, 16.0) cm in easy laryngoscopy (p-value 0.05). The mean distance from skin to epiglottis was 12.2 ± 3.3 mm Mean of distance from skin to epiglottis in difficult laryngoscopy was 12.5 ± 3.3 mm compared with 10.6 ± 2.9 mm in easy laryngoscopy (p-value 0.05). Multivariate logistic regression indicated the following factors associated with difficult laryngoscopy: age more than 43 years (A), thyromental distance more than 68 mm(B) and the distance from skin to epiglottis more than 13 mm(C). The scores to predict difficult laryngoscopy was calculated as 8A + 7B + 6C based on the data from our study. One point is given for A if age was more than 43 years old, 1 point is given for B if thyromental distance was less than 6.8 cm and 1 point is given for C if the distance from skin to epiglottis by ultrasonography was more than 13.0 cm. The maximum predicting score is 21, which indicates a probability of difficult laryngoscopy among our patients of 36.36%, odds 0.57, likelihood ratio 3.29 and area under the ROC curve of 0.77, indicative of a good predictive score. CONCLUSIONS: Age, thyromental distance and ultrasonography for the distance from skin to epiglottis can predict difficult laryngoscopy among obese Thai patients. The predictive score indicates the probability of difficult laryngoscopy.

Predictive values of the modified Mallampati test, upper lip bite test, thyromental distance and ratio of height to thyromental distance to predict difficult laryngoscopy in pediatric elective surgical patients 5-12 years old at selected Addis Ababa governmental hospitals, Ethiopia: a multicenter cross-sectional study.

BACKGROUND: Maintaining patent airways is vital in pediatric anesthetic management. Failure to manage and anticipate difficult laryngoscopy (DL) preoperatively is the leading cause of morbidity and mortality. Data on the predictive values of screening parameters in predicting DL are limited in children. Therefore, this study aimed to assess the predictive value of the modified Mallampati test (MMT), upper lip bite test (ULBT), thyromental distance (TMD), and ratio of height to thyromental distance (RHTMD) in predicting DL in children aged 5-12 years at selected Addis Ababa governmental hospitals in Ethiopia. METHODS: A multicenter cross-sectional study was conducted on 141 elective pediatric surgical patients aged 5 to 12 years selected using a systematic random sampling technique at three governmental hospitals from December 1, 2021, to April 30, 2022. The collected data were entered and analysed by SPSS version 26. Chi-square and Fisher's exact tests were used to compare categorical variables. The receiver operating characteristic curve analysis was used to compare the accuracy of MMT, ULBT, TMD, and RHTMD against DL. A P value < 0.05 was considered statistically significant. RESULTS: The magnitude of DL was 15.6%. MMT has the highest sensitivity (86.4%), specificity (91.6%), and negative predictive value (NPV) (97.3%) compared to other tests. The ULBT also has a high sensitivity (72.7%) and specificity (84%) with comparable diagnostic accuracy (90.8%) with the MMT (P < 0.05). The sensitivity, specificity, positive predictive value (PPV), NPV, and accuracy of TMD were 63.6%, 95.8%, 73.7%, 93.4%, and 82.2%, respectively. The RHTMD has the lowest specificity (63.6%), PPV (22.5%), NPV (91.4%), and accuracy (56.7%) in predicting DL. CONCLUSION: The MMT and ULBT are good screening tests, followed by the TMD in predicting DL, while the RHTMD was the least accurate predictor. Because no single test has 100% predictive value, a combination of screening tests is advised in pediatrics for predicting DL.

Evaluation of anthropometric measurements and clinical tests in the diagnosis of difficult airway in patients undergoing head and neck surgery.

BACKGROUND: The aim of this study is to research the incidence of difficult airways and the effectiveness of anthropometric measurements and clinical tests used to predict difficult airways in patients undergoing head and neck surgery. METHODS: This study was performed on a total of 200 patients over the age of 18 who underwent head and neck surgery between December 2019 and March 2020. The demographic data of the patients in the preoperative period, previous operations/ radiotherapy history applied to the head and neck region, and obstructive sleep apnea syndrome symptoms were recorded. In the physical examination, the jaw structure, mouth opening, jaw movement, and tooth structure of the patients, modified Mallampati classification, head and neck movements, neck circumference, thyromental and sternomental distance, atlantooccipital joint mobility, upper lip bite test, Wilson risk scoring, and Cormack-Lehane classification were evaluated. RESULTS: The difficult laryngoscopy rate was identified as 19%, and the difficult intubation rate as 8%. Operation history related to head and neck (p = 0.002), presence of at least two of the obstructive sleep apnea syndrome symptoms (p = 0.008), Modified Mallampati score (p = 0.009), Wilson risk score (p = 0.004), upper lip bite test (p < 0.0001) and mouth opening (p = 0.001) were found to be associated with difficult laryngoscopy. Modified Mallampati score (p = 0.002), Wilson risk score (p < 0.0001), upper lip bite test (p < 0.0001), mouth opening (p < 0.0001), sternomental distance (p = 0.003), Atlantooccipital joint mobility (p = 0.001), and Cormack-Lehane classification (p < 0.0001) were found to be associated with difficult intubation. According to multiple logistic regression analysis, the results obtained for sternomental distance and mouth opening were OR 0.8, 95% CI 0.6-1.1 and OR 0.2, 95% CI 0.1-0.4, respectively. DISCUSSION: In patients who underwent head and neck surgery, it was observed that the frequency of difficult airway was higher, and particularly the Modified Mallampati score, Wilson risk score, upper lip bite test, and mouth opening were associated with both difficult laryngoscopy and difficult intubation.

Development and validation of a difficult laryngoscopy prediction model using machine learning of neck circumference and thyromental height.

BACKGROUND: Predicting difficult airway is challengeable in patients with limited airway evaluation. The aim of this study is to develop and validate a model that predicts difficult laryngoscopy by machine learning of neck circumference and thyromental height as predictors that can be used even for patients with limited airway evaluation. METHODS: Variables for prediction of difficulty laryngoscopy included age, sex, height, weight, body mass index, neck circumference, and thyromental distance. Difficult laryngoscopy was defined as Grade 3 and 4 by the Cormack-Lehane classification. The preanesthesia and anesthesia data of 1677 patients who had undergone general anesthesia at a single center were collected. The data set was randomly stratified into a training set (80%) and a test set (20%), with equal distribution of difficulty laryngoscopy. The training data sets were trained with five algorithms (logistic regression, multilayer perceptron, random forest, extreme gradient boosting, and light gradient boosting machine). The prediction models were validated through a test set. RESULTS: The model's performance using random forest was best (area under receiver operating characteristic curve = 0.79 [95% confidence interval: 0.72-0.86], area under precision-recall curve = 0.32 [95% confidence interval: 0.27-0.37]). CONCLUSIONS: Machine learning can predict difficult laryngoscopy through a combination of several predictors including neck circumference and thyromental height. The performance of the model can be improved with more data, a new variable and combination of models.

The evaluation of maximum condyle-tragus distance can predict difficult airway management without exposing upper respiratory tract; a prospective observational study.

BACKGROUND: Routine preoperative methods to assess airway such as the interincisor distance (IID), Mallampati classification, and upper lip bite test (ULBT) have a certain risk of upper respiratory tract exposure and virus spread. Condyle-tragus maximal distance(C-TMD) can be used to assess the airway, and does not require the patient to expose the upper respiratory tract, but its value in predicting difficult laryngoscopy compared to other indicators (Mallampati classification, IID, and ULBT) remains unknown. The purpose of this study was to observe the value of C-TMD to predict difficult laryngoscopy and the influence on intubation time and intubation attempts, and provide a new idea for preoperative airway assessment during epidemic. METHODS: Adult patients undergoing general anesthesia and tracheal intubation were enrolled. IID, Mallampati classification, ULBT, and C-TMD of each patient were evaluated before the initiation of anesthesia. The primary outcome was intubation time. The secondary outcomes were difficult laryngoscopy defined as the Cormack-Lehane Level > grade 2 and the number of intubation attempts. RESULTS: Three hundred four patients were successfully enrolled and completed the study, 39 patients were identified as difficult laryngoscopy. The intubation time was shorter with the C-TMD>1 finger group 46.8 ± 7.3 s, compared with the C-TMD<1 finger group 50.8 ± 8.6 s (p<0.01). First attempt success rate was higher in the C-TMD>1 finger group 98.9% than in the C-TMD<1 finger group 87.1% (P<0.01). The correlation between the C-TMD and Cormack-Lehane Level was 0.317 (Spearman correlation coefficient, P<0.001), and the area under the ROC curve was 0.699 (P<0.01). The C-TMD < 1 finger width was the most consistent with difficult laryngoscopy (κ = 0.485;95%CI:0.286-0.612) and its OR value was 10.09 (95%CI: 4.19-24.28), sensitivity was 0.469 (95%CI: 0.325-0.617), specificity was 0.929 (95%CI: 0.877-0.964), positive predictive value was 0.676 (95%CI: 0.484-0.745), negative predictive value was 0.847 (95%CI: 0.825-0.865). CONCLUSION: Compared with the IID, Mallampati classification and ULBT, C-TMD has higher value in predicting difficult laryngoscopy and does not require the exposure of upper respiratory tract. TRIAL REGISTRATION: The study was registered on October 21, 2019 in the Chinese Clinical Trial Registry ( ChiCTR1900026775 ).

Preoperative X-ray C2C6AR is applicable for prediction of difficult laryngoscopy in patients with cervical spondylosis.

BACKGROUND: Airway management is one of the most important techniques in anesthesia practice and inappropriate airway management is related with airway injury, brain hypoxia, and even death. The patients with cervical spondylosis are often confronted with difficult laryngoscopy who are more prone to appear difficult airway, so it is important to figure out valuable predictors of difficult laryngoscopy in these patients. METHODS: We randomly enrolled 270 patients undergoing elective cervical spine surgery and analyzed the cervical mobility data in predicting difficult laryngoscopy. The preoperative X-ray radiological indicators were measured by an attending radiologist. 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 the hyomental distance (HMD, the distance between the hyoid bone and the tip of the chin) and the hyomental distance ratio (HMDR, the ratio between HMD in the extension position and the one in the neutral position) might not be suitable indicators in patients with cervical spondylosis. Binary multivariate logistic regression (backward-Wald) analyses identified two independent correlative factors from the cervical mobility indicators that correlated best as a predictor of difficult laryngoscopy: modified Mallampati test (MMT) and C2C6AR (the ratio of the angle between a line passing through the bottom of the second cervical vertebra and a line passing through the bottom of the sixth cervical vertebra in the extension position and the one in the neutral position). The odds ratio (OR) and 95 % CI were 2.292(1.093-4.803) and 0.493 (0.306-0.793), respectively. C2C6AR exhibited the largest area under the curve (0.714; 95 % CI 0.633-0.794). CONCLUSIONS: C2C6AR based on preoperative X-ray images may be the most accurate predictor of cervical mobility indicators for difficult laryngoscopy in patients with cervical spondylosis. TRIAL REGISTRATION: The study was registered at the Chinese Clinical Trial Registry ( http://www.chictr.org.cn ; identifier: ChiCTR-ROC-16,008,598) on June 6, 2016.

Ratio of height to thyromental distance: a comparison with mallampati and upper lip bite test for predicting difficult intubation in Pakistani population.

OBJECTIVE: To compare the accuracy of three diagnostic tests in predicting difficult laryngoscopy using Cormack and Lehane grade as the gold standard. METHODS: The cross-sectional study was conducted at the Aga Khan University Hospital, Karachi, from August 2014 to August 2015, and comprised patients who required endotracheal intubation for elective surgical procedures. The primary investigator used ratio of height to thyromental distance, upper lip bite test and the modified Mallampati test for assessing the airway correlated with laryngoscopic view based on Cormack and Lehane grading. Data was analysed using SPSS 19. RESULTS: Of the 383 patients, 59(15.4%) were classified as difficult cases of laryngoscopy. The sensitivity, specificity, positive predictive value, negative predictive value and accuracy of ratio of height to thyromental distance were 84.7%, 90.1%, 60.9%, 97%, 89.3%; and those the corresponding values for the upper lip bite test were 83.1%, 89.2%, 58.3%, 96.7% and 88.3%. The values for the modified Mallampati test were 30.5%, 84.3%, 26.1%, 86.9% and 79.9% respectively. The area under receiver-operating characteristic curve for the first two tests was significantly more than for the modified Mallampati test (p<0.01). CONCLUSIONS: RHTMD and ULBT both are acceptable alternatives for prediction of difficult laryngoscopy as a simple, single bed-side test.

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 thyromental height test with ratio of height to thyromental distance, thyromental distance, and modified Mallampati test in predicting difficult laryngoscopy: A prospective study.

BACKGROUND AND AIMS: Preoperative airway assessment to predict patients with difficult laryngoscopy is always crucial for anesthesiologists. Several predictive tests have been studied by various authors in quest of finding the best airway predictor. Recently, a new airway predictor, thyromental height test (TMHT) has been reported to have good predictive value in assessing difficult airway. We conducted this study with primary aim to evaluate the diagnostic accuracy of TMHT and to compare it with other established airway predictors, such as ratio of height to thyromental distance (RHTMD), thyromental distance (TMD), and modified Mallampati test (MMT) for predicting difficult laryngoscopy. MATERIAL AND METHODS: This prospective, observational study was conducted in 550 patients of either sex aged >18 years scheduled for elective surgery under general anesthesia. The patients' airway was assessed preoperatively by two anesthetists. Standard anesthetic protocol was followed in all the patients. The laryngoscopic view was graded according to Cormack-Lehane scale. The receiver operating characteristic (ROC) curve was used to calculate the ideal cut off values for TMHT and RHTMD. Standard formulae were used to calculate validity indexes. RESULTS: The incidence of difficult laryngoscopy was 10%. The cut-off value for TMHT and RHTMD were 5.1 cm and 19.5, respectively. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of TMHT were 78.18%, 93.94%, 58.90%, and 97.48%, respectively. The highest sensitivity, PPV, and NPV were observed with TMHT as compared with RHTMD, TMD, and MMT (P < 0.0001). CONCLUSIONS: TMHT is the best predictive test with highest accuracy and odds ratio for predicting difficult airway out of all predictive tests evaluated.

Thyromental distance ("Patil") revisited : Knowledge and performance of a basic airway screening tool among European anesthetists.

Predicting and managing the difficult airway is a lifesaving and vital basic task for the anesthetist. Current guidelines of all important societies include thyromental distance (TMD, "Patil") as a possible predictor for a difficult airway and includes two important aspects for airway management: the mandibular space and the flexibility of the cervical spine. We evaluated knowledge and execution regarding TMD for predicting a difficult airway on participants at the Euroanaesthesia (ESA) congress and German Anaesthesia Congress (DAC) in 2014. Our evaluation consisted of a theoretical part with questions regarding general knowledge and a practical evaluation with anesthetists performing on a human airway model. Practical evaluations were performed separately from other participants. During the DAC 245 (ESA 230) physicians participated, of which 64% were male (ESA 58%). At the DAC 182 (74.3%) and ESA 82 (35.6%) participants knew about Patil/TMD. Its use as a predictive score for a difficult airway was known by 122 (49.8%; DAC) and 79 (34.4%; ESA) participants. The correct definition for intubation was given by 45 (25.7%) at the DAC and 56 (24.3%) at ESA. Only 40-41% of the participants measured the correct distance for TMD. Only 6.1-6.5% completed both the theoretical and practical parts correctly. As non-invasive TMD includes two different aspects of patient airways and is part of current guidelines, education and training must be extended to assure adequate evaluation in the future.

Upper lip bite test for prediction of difficult airway: A systematic review.

BACKGROUND AND OBJECTIVE: Upper lip bite test (ULBT) is one of the various bedside tests used for prediction of difficult laryngoscopic intubation. However, its usefulness is not still very clear, and there is controversy regarding its accuracy. The aim of this systematic review was to determine the accuracy of the ULBT for predicting difficult airway including difficult laryngoscopy or difficult tracheal intubation. METHOD: We searched the databases of PubMed, Scopus, and Google scholar for prospective studies published up until October 2016 assessing the accuracy of ULBT in comparison to Cormack-Lehane grading. The selected keywords were "upper lip bite test", "upper lip catch test", "prediction", "difficult airway", "difficult laryngoscopy", "difficult intubation". Inclusion criteria were studies assessing ULBT for prediction of difficult intubation, considering Cormack-Lehane grade III and IV as difficult airway, written in English, and reporting sensitivity, specificity, NPV, PPV, and accuracy. Exclusion criteria were studies not reporting accuracy or not having enough data for its calculation. Based on the mentioned criteria, 27 studies enrolling 18141 patients were included. This systematic review was performed based on the guidelines on conducting systematic reviews of diagnostic studies. RESULTS: Prevalence of airway difficulties according to the direct laryngoscopic view varied from 2.8% to 27% and according to the ULBT was from 2% to 21%. In 11 of the 27 studies, sensitivity of ULBT in prediction of difficult airway was more than 70%. All of the studies except one showed a high specificity for ULBT (>85%). Moreover, these studies indicated a high NPV. Accuracy of ULBT was >85% in 24 out of 27 studies. CONCLUSION: It appears that ULBT is a useful bedside test for evaluation of patient airway before the general anesthesia.