Upper Lip Bite Test Research Articles

Evaluation of preoperative difficult airway prediction methods for adult patients without obvious airway abnormalities: a systematic review and meta-analysis

BackgroundThis systematic review aims to assist clinical decision-making in selecting appropriate preoperative prediction methods for difficult tracheal intubation by identifying and synthesizing literature on these methods in adult patients undergoing all types of surgery.MethodsA systematic review and meta-analysis were conducted following PRISMA guidelines. Comprehensive electronic searches across multiple databases were completed on March 28, 2023. Two researchers independently screened, selected studies, and extracted data. A total of 227 articles representing 526 studies were included and evaluated for bias using the QUADAS-2 tool. Meta-Disc software computed pooled sensitivity (SEN), specificity (SPC), positive likelihood ratio (PLR), negative likelihood ratio (NLR), and diagnostic odds ratio (DOR). Heterogeneity was assessed using the Spearman correlation coefficient, Cochran’s-Q, and I2 index, with meta-regression exploring sources of heterogeneity. Publication bias was evaluated using Deeks’ funnel plot.ResultsOut of 2906 articles retrieved, 227 met the inclusion criteria, encompassing a total of 686,089 patients. The review examined 11 methods for predicting difficult tracheal intubation, categorized into physical examination, multivariate scoring system, and imaging test. The modified Mallampati test (MMT) showed a SEN of 0.39 and SPC of 0.86, while the thyromental distance (TMD) had a SEN of 0.38 and SPC of 0.83. The upper lip bite test (ULBT) presented a SEN of 0.52 and SPC of 0.84. Multivariate scoring systems like LEMON and Wilson’s risk score demonstrated moderate sensitivity and specificity. Imaging tests, particularly ultrasound-based methods such as the distance from the skin to the epiglottis (US-DSE), exhibited higher sensitivity (0.80) and specificity (0.77). Significant heterogeneity was identified across studies, influenced by factors such as sample size and study design.ConclusionNo single preoperative prediction method shows clear superiority for predicting difficult tracheal intubation. The evidence supports a combined approach using multiple methods tailored to specific patient demographics and clinical contexts. Future research should focus on integrating advanced technologies like artificial intelligence and deep learning to improve predictive models. Standardizing testing procedures and establishing clear cut-off values are essential for enhancing prediction reliability and accuracy. Implementing a multi-modal predictive approach may reduce unanticipated difficult intubations, improving patient safety and outcomes.

The Diagnostic Value of Sub-mental Fat Measurement for Prediction of Difficult Laryngoscopy and Intubation: A Randomized Prospective Study

Background: Difficult airway management poses a high-risk procedure, potentially leading to patient mortality. Despite significant advancements in modern anesthesia over the years, there remains a lack of a single reliable tool for predicting difficult airways. Objectives: This study aims to examine neck fat diameter as a potential predictor of airway difficulty. Methods: Two hundred fifty patients participated in the study. Airway parameters, including Mallampati score, mandibular protrusion, upper lip bite test, thyromental distance, neck movements, and neck fat diameter, were documented. Results: Among our study population, 48 patients experienced difficult intubation. The Mann-Whitney test revealed that submental fat was significantly greater in the difficult intubation group (P-value < 0.001). Based on the best subset variable selection, submental fat, thyromental distance (model 1), and age (model 2) were selected to participate in the multivariate regression model. Each one mm increase in neck fat was associated with a 30% increase in the odds of difficult intubation (P-value < 0.001) in the univariate logistic model. After adjusting for thyromental distance, age, and gender, the odds of difficult intubation were approximately 2 times higher in patients with 1 mm more neck fat (P-value 0.007). The area under the curve of the Receiver Operating Characteristics curve and McFadden's pseudo-R squared of the multivariate model were 0.998 and 0.91, respectively. Conclusions: Neck fat diameter serves as a reliable and straightforward predictor of airway difficulty and can be used alone or in conjunction with other predictors for the prediction of difficult airway management.

A new score for airway assessment using clinical and ultrasound parameters.

Over the last few years, ultrasonography has been introduced as the fifth pillar to patient's bedside physical examination. Clinical assessments aim to screen and look for airway difficulties to predict difficult intubations, but none have demonstrated a significant predictive capacity. Recent systematic reviews have established a correlation between ultrasound imaging and difficult direct laryngoscopy. The primary objective of this study was to determine whether the utilization of ultrasonography to examine the upper airway could accurately predict difficult direct laryngoscopy. This is a prospective observational study including 102 adult patients that required general anesthesia for elective surgery. Preoperatively, clinical airway assessments were performed. Data such as Mallampati-Samsoon grade (MS), upper lip bite test (ULBT), thyromental (TMD) and sternomental distance (SMD), cervical circumference (CC) and the Arné risk index were collected. Ultrasound evaluation was taken at five different levels in two planes, parasagittal and transverse. Therefore, the following measurements were registered: distance from skin to hyoid bone (DSHB), distance from skin to thyrohyoid membrane (DSTHM), distance from skin to epiglottis (DSE), distance from skin to thyroid cartilage (DSTC) and distance from hyoid bone and thyroid cartilage (DHBTC). Patients were divided into two groups based on the difficulty to perform direct laryngoscopy, according to Cormack-Lehane (C-L) classification. Grades I and II were classified as easy laryngoscopy and grades III or IV as difficult. Logistic regression models and the Receiver Operating Characteristic (ROC) curve was employed to determine the diagnostic precision of ultrasound measurements to distinguish difficult laryngoscopy (DL). The following risk score for DL was obtained, DSTHM ≥ 1.60 cm (2 points), DSTC ≥ 0.78 cm (3 points) and gender (2 points for males). The score can range from 0 to 7 points, and showed and AUC (95% CI) of 0.84 (0.74-0.95). A score of 5 points or higher indicates a 34-fold increase in the risk of finding DL (p = 0.0010), sensitivity of 91.67, specificity of 75.56, positive predictive value of 33.33, and negative predictive value of 98.55. The use of ultrasonography combined with classic clinical screening tests are useful tools to predict difficult direct laryngoscopy.

Prevalence of obstructive sleep apnea syndrome and predictors of difficult orotracheal intubation.

Obstructive sleep apnea syndrome (OSAS) is an underdiagnosed condition that causes recurrent episodes of partial or total collapse of the upper airways during sleep. It is associated with perioperative pulmonary complications. The STOP-BANG is a screening tool for assessing patients at risk of OSAS. The aim of this study was to assess the prevalence of patients with OSAS during pre-anesthetic evaluation at a hospital and its correlation with predictors of ventilation and difficult airway. This is an observational, cross-sectional study carried out from January 2022 to September 2023. The questionnaire comprised demographic data (age, weight, BMI, type of surgery, and anesthesia), the STOP-BANG, predictors of difficult orotracheal intubation (Mallampati, mouth opening, thyromental distance, cervical mobility, and upper lip bite test), and predictors of difficult ventilation through a facial mask (male sex, absence of teeth, presence of beard, obesity, and >55 years). The study had the participation of 221 patients, of whom 121 presented with a STOP-BANG ≥3, with a prevalence of 54.2%. All patients undergoing bariatric surgeries presented STOP-BANG ≥3. No significant statistical relationships were found between predictors of difficult orotracheal intubation and STOP-BANG ≥3. However, significant statistical relationships were found in relation to predictors of difficult ventilation through the facial mask.

Pilot multicenter study to determine the utility of point-of-care ultrasound to predict difficulty of tracheal intubation using videolaryngoscopy with the McGrath™ Mac videolaryngoscope.

Clinical airway screening tests used to predict difficulties during airway management have low sensitivity and specificity. Point-of-care airway ultrasound has described measurements related to problems with difficult direct laryngoscopy. Nevertheless, the correlation between ultrasound parameters and videolaryngoscopy has not been published yet. The aim of this multicenter, prospective observational pilot study was to evaluate the applicability of clinical parameters and ultrasound measurements to find potential tracheal intubation difficulties when videolaryngoscopy is used. Preoperatively, six clinical airway assessments were performed: (1) modified Mallampati score, (2) thyromental distance, (3) sternomental distance, (4) interincisal distance, (5) upper lip bite test, and (6) neck circumference. Six ultrasound parameters were measured in awake patients: (1) distance from skin to hyoid bone, (2) distance from skin to epiglottis, (3) hyomental distance in neutral head position, (4) hyomental distance in head-extended position, (5) distance from skin to the deepest part of the palate, and (6) sagittal tongue area. And finally, there was one ultrasound measure obtained in anesthetized patients, the compressed sagittal tongue area during videolaryngoscopy. The difficulty for tracheal intubation using a McGrath™ Mac videolaryngoscope, the percentage of glottic opening, and Cormack-Lehane grade were also assessed. In this cohort of 119 subjects, tongue dimensions, particularly the sagittal tongue area, showed a robust association with increased intubation difficulty using videolaryngoscopy. A multiparametric model combining the following three ultrasound variables in awake patients: (a) the distance from skin to epiglottis, (b) the distance from skin to the deepest part of the palate, and (c) the sagittal tongue area, yielded a sensitivity of 92.3%, specificity of 94.5%, positive predictive value of 82.8%, and negative predictive value of 97.8% (p < 0.001). Point-of-care airway ultrasound emerges as a more useful tool compared to traditional clinical scales to anticipate possible challenges during videolaryngoscopic intubation.

COMPARISON OF TOTAL AIRWAY SCORES AND INTUBATION DIFFICULTY SCORES IN DENTAL PROCEDURES PERFORMED UNDER GENERAL ANESTHESIA: A RETROSPECTIVE STUDY

The Total Airway Score, determined by eight bedside tests during the preoperative period, and the Intubation Difficulty Scale, assigned during intubation, are both used to describe and predict difficult intubation. The aim of this study is to investigate the correlation between the Total Airway Score and the Intubation Difficulty Scale.Two hundred,American Society of Anesthesiologists ASA 1-3 patients elective dental treatment, maxillofacial surgery under general anesthesia were included in the study. Airway evaluation was performed preoperatively by total airway score which were; Mallampati classification, thyromental and sternomental distance measurement, head and neck mobility,body mass index (BMI), presence of buck teeth, inter incisors gap, upper lip bite test. After endotracheal intubation, the patients were divided into two groups as a healthy group (intubation difficulty scale (IDS)&amp;lt;4) and difficult intubation (IDS ≥4) according to their estimated difficult intubation scores with seven variables and compared with patients with total airway score &amp;gt; 3 in two groups. In this study, total airway score (&amp;gt; 3), thyromental distance (&amp;lt;6cm), upper lip bite test (class III), mallampati classification (≥ class III), inter incisors gap (&amp;lt;3 cm) and buck teeth (&amp;gt; 0.5) respectively 49.45 (95% CI = 4.75-515.45, P &amp;lt;0.05) 7.72 (95% CI = 1.81-32.9, P &amp;lt;0.05), 21.12 (95% CI = 2.31-192.27, P &amp;lt;0.05), 1.92 (CI 95% = 0.51-7.22), 3.54 (95% CI-) 2.31 (95% CI = 0.49-10.78) was detected.It is concluded that total airway score (&amp;gt; 3), upper lip bite test (class III),thyromental distance measurement (&amp;lt;6 cm), which we use in predicting difficult intubation are the most useful preoperative evaluation factors.

A comparison of ratio of patient’s height to thyromental distance with modified mallampati test and upper lip bite test for prediction of difficult laryngoscopy

Various airway evaluation tests are performed to predict difficult intubation. The ratio of Height to thyromental distance has been reported to have a good predictability. This study tested the performance of ratio of height to thyromental distance and compared it with commonly performed airway evaluation tests: the modified Mallampati test and upper lip bite test. This descriptive study was conducted in 120 patients presenting for surgery under general anesthesia with endotracheal intubation. Preoperative airway assessment was done using Modified Mallampati test, upper lip bite test and ratio of height to thyromental distance. The Cormack and Lehane grading was done during laryngoscopy to determine easy or difficult visualization of larynx. Sensitivity, specificity, positive predictive value, negative predictive value and accuracy of three tests were calculated. Difficult laryngoscopy was seen in 9 patients (7.5%). The sensitivity, specificity, positive predictive value, negative predictive value respectively for the tests were modified Mallampati test (22.2%, 89.2%, 14.3% and 93.4%), upper lip bite test (22.2%, 100%, 100% and 94.1%), ratio of height to thyromental distance (77.8%, 95.5%, 58.3% and 94.16%). In conclusion, we found that the ratio of patient’s height to thyromental distance performed better than MMT and ULBT in predicting difficult visualization of larynx in our population.

Can chin-nape circumference and the ratio of neck circumference to chin-nape circumference predict difficult mask ventilation or difficult intubation in obese patients?

We aimed to evaluate the success of the ratio of chin-nape circumference (CNC) and neck circumference (NC) to CNC in predicting difficult mask ventilation (DMV) or difficult intubation (DI). Eighty-seven obese patients (body mass index ≥ 30) were evaluated between September 15, 2019 and September 15, 2020. Mallampati score, mouth opening, upper lip bite test, distance between incisors, thyromental distance (TMD), sternomental distance (SMD), and thyromental height were recorded. NC and CNC were measured in a neutral position. The ratio of NC to TMD and the ratio of NC to CNC were calculated. Mask ventilation was graded according to the method described by Han et al (Grade 3 or 4 equals DMV). DI assessment was performed using the intubation difficulty scale (IDS, IDS < 5 equals easy intubation, IDS ≥ 5 equals DI). Logistic regression analysis was performed to identify the variables thought to be effective in DMV and DI. Receiver operating characteristic curves were generated for each parameter considered effective. DMV was found in 17.2% (n = 15) of the patients included in the study, and DI was found in 16.1% (n = 14). The relationship between DMV and age, male gender, obstructive sleep apnea syndrome, NC, ratio of NC to TMD, ratio of NC to SMD, ratio of NC to CNC, and CNC was significant. Male gender and NC >45.5 cm were independent risk factors for DMV. The relationship between DI and distance between incisors, NC, ratio of NC to TMD, ratio of NC to SMD, and CNC was significant. A distance between the incisors < 4.85 cm and a NC > 41.5 cm were found to be independent risk factors for DI. CNC may predict DMV and DI in obese patients. The ratio of NC to CNC may predict DMV in obese patients.

Observation of the validity of the upper lip bite test in predicting difficult intubation

The upper lip bite test (ULBT) is considered an effective method for predicting difficult airways, but data on the ULBT for predicting difficult tracheal intubation are lacking. This study aimed to examine the clinical utility of the ULBT in predicting difficult endotracheal intubation. We conducted an observational case-cohort study of adult patients undergoing elective surgery and requiring endotracheal intubation for general anesthesia. Difficult airway assessment was performed on the recruited patients before the operation, including the ULBT, mouth opening, thyromental distance, modified Mallampati test, and body mass index. The primary outcome was the incidence of difficult tracheal intubation. The receiver operating characteristic curve analysis was used to compare the performance of variables in predicting difficult tracheal intubation. We successfully recruited 2522 patients for analysis and observed 64 patients with difficult tracheal intubation. When predicting difficult tracheal intubation, grade 2 ULBT had a sensitivity of 0.75 and a specificity of 0.54, and grade 3 had a sensitivity of 0.28 and a specificity of 0.75. Compared with mouth opening, the area under the receiver operating characteristic curve of the ULBT was lower in predicting difficult tracheal intubation (0.69 [95% confidence interval: 0.67–0.71] vs. 0.84 [95% confidence interval: 0.82–0.87], P < 0.05).Clinical Trials Registry: ChiCTR-ROC-16009050, principal investigator: Weidong Yao.

Comparison between clinical and ultrasonographic parameters in predicting difficult airway: An observational prospective study

Introduction : Various clinical tests are applied at the bedside to predict difficult airway during the pre-anaesthetic examination. Ultrasonography can be used to evaluate the airway and predict difficulty in laryngoscopy and endotracheal intubation.&#x0D; Objective : To compare the various clinical and ultrasonographic parameters in predicting difficult airway.&#x0D; Methodology: This prospective observational study was carried out at Birat Medical College and Teaching Hospital. The clinical parameters obtained were Modified Mallampati Grade (MMP), Upper Lip Bite Test (ULBT) and Thyromental Distance (TMD) and the ultrasonographic (USG) parameters used were Tongue Volume (TV), Hyomental Distance Ratio (HMDR) and distance of soft tissue from skin to hyoid bone (DSHB).These results were correlated with Cormack-Lehane (CL) grade during laryngoscopy of 200 patients. The sensitivity, specificity, Receiver Operating Characteristic (ROC) curve along with Area under the curve (AUC) was calculated for each parameter.&#x0D; Result: Incidence of difficult airway was 15.5%. The sensitivity and specificity of ultrasonographic tongue volume (TV) was higher among all parameters in predicting difficult airway. The specificity of HMDR and DSHB were better compared to clinical parameters.&#x0D; Conclusion: The use of ultrasound in pre-anaesthetic examination can be a viable tool along with clinical parameters for prediction of difficult airway.

Evaluation and comparison of sonographic difficult airway assessment parameters with clinical airway predictors.

None of the clinical difficult airway predictors are 100% sensitive and specific. Ultrasound is being used for airway assessment, but there is still no established parameters or model to predict difficult laryngoscopy. This observational study was planned to determine the predictive ability of clinical and sonography-based airway assessment parameters for difficult laryngoscopy and intubation. A total of 130 patients of 18-60 years of age undergoing elective intubation were included. The distribution of Cormack-Lehane (CL) grade and intubation difficulty scale (IDS) was correlated with the clinical and sonographic screening parameters for difficult airways. The prevalence of difficult laryngoscopy and difficult intubation in our study was 17.6% and 11.5%, respectively. Mallampati grade (MMG), upper lip bite test (ULBT), neck circumference, hyomental distance ratio (HMDR), tongue thickness (TT), skin to epiglottis/epiglottis to vocal cord distance (SED/E-VC), and mandibular condylar mobility (MCM) had significant association with the difficult laryngoscopy and MMG, neck circumference, SED, SED/E-VC; MCM had significant association with the difficult intubation. The combination of these predictors showed better diagnostic ability for difficult airways. Model 1 based on ultrasound parameters showed an area under the curve (AUC) of 0.848 (CI- 0.748-0.947, P value < 0.0001) and model 2 based on combined clinical and ultrasound parameters showed an AUC of 0.755 (95% CI- 0.631-0.879, P value < 0.0001). Ultrasound-based airway predictors can help in predicting difficult laryngoscopy and intubation along with the clinical parameters. Individual sonographic predictors have moderately satisfactory diagnostic profiles. The models based on combined tests have better diagnostic value.

Evaluation of thyromental height test as a single anatomical measure for prediction of difficult laryngoscopy: a prospective observational study

BackgroundPreoperative airway assessment is essential to predict difficult airway so that adequate planning could be made to secure the airway. Various airway tests have been devised to improve diagnostic accuracy but none of the tests individually have proven to be adequate. Recently, a new airway predictor thyromental height test (TMHT) appears to be a more accurate predictor of difficult laryngoscopy than the existing anatomical measurements. The aim of this study is to evaluate the accuracy of the TMHT and compare it with various screening tests to determine whether TMHT can prove to be a more comprehensive and accurate test for predicting difficult laryngoscopy. Total 150 patients aged > 18 years of either sex with American Society of Anaesthesiologist physical status I—III scheduled for elective surgery under general anaesthesia requiring tracheal intubation were included in this prospective observational study. All patients were subjected to a preoperative airway assessment test including TMHT, modified Mallampati test, upper lip bite test, interincisior gap, thyromental distance and sternomental distance. Intraoperatively direct laryngoscopy was done and the grading of laryngoscopic view was done according to CL.ResultsThe preoperative data and CL grading were used to evaluate the accuracy of TMHT and compared the sensitivity, specificity, positive and negative predictive value with other tests.Twenty six (17.33%) patients had difficult laryngoscopy and 18 patients (12%) required bougie/stylet to facilitate intubation. TMHT had the highest sensitivity (76.92%), specificity (98.38%), PPV (90.90%), NPV (95.31%) and accuracy (94.67%) when compared to other tests.ConclusionsTMHT is a simple bedside test with higher sensitivity and specificity for predicting difficult laryngoscopy as compared to other screening tests.Future study should be done to define ethinicity, race, age groups and gender specific cut off values of TMHT for accurate validation of prediction in difficult laryngoscopy.

Retrospective Investigation of Difficult Airway Cases Encountered in Bursa Uludag˘ University Medical Faculty Operating Room.

Ensuring airway patency and proper management of ventilation by anticipating difficulties that can occur in airway control are vital in preventing anaesthesia-related complications. We aimed to determine the role of preoperative assessment findings in difficult airway management. In this study, critical incident records of difficult airway patients between 2010 and 2020 in the operating room of Bursa Uludag˘ University Medical Faculty were retrospectively analysed. A total of 613 patients, whose records were fully accessible, were grouped as paediatric (under 18 years old) and adult (18 years and over). The success rate for maintaining an airway in all patients was 98.7%. Pathological situations which cause difficult airways were head and neck region malignancies in adult patients and congenital syndromes in paediatric patients. Anatomical reasons that cause difficult airway were anterior larynx (31.1%) and short muscular neck (29.7%) in adult patients and small chin (38.0%) in paediatric patients. A significant statistical relationship was found between difficult mask ventilation and increased body mass index, male gender, modified Mallampati class 3-4, and thyromental distance <6 cm (P = .001, P < .001, P < .001, and P < .001, respectively). The correlation of Cormack-Lehane grading with modified Mallampati classification, upper lip bite test, and mouth opening distance was statistically significant (P < .001, P < .001, and P < .001, respectively). In male patients with increased body mass index, modified Mallampati test class of 3-4 and thyromental distance of < 6 cm should suggest the possibility of difficult mask ventilation. In modified Mallampati classification and upper lip bite tests, the possibility of difficult laryngoscopy should be considered as class increases and mouth opening distance becomes shorter. Preoperative assessment, including a good history taken from the patient and a complete physical examination, is crucial to provide solutions for difficult airway management.

Evaluation of ratio of height to thyromental distance as a predictor of difficult visualization of larynx: A prospective observational single center study

BackgroundRatio of height to thyromental distance (RHTMD) is a relatively new predictor of difficult visualization of larynx (DVL). Studies on Indian population are limited and none is carried out in the northeastern part of India. AimsThe primary aim was to assess the performance of RHTMD as a predictor of DVL and compare its predictive performance with modified Mallampati test. The secondary aim was to compare the performance of RHTMD with sterno-mental distance, inter-incisor distance and upper-lip bite test, as a predictor of DVL. We also aimed to evaluate the performance of RHTMD as a predictor of Intubation difficulty scale (IDS) > 5. MethodsIn this prospective, observer blinded, single center study, adult patients of either sex scheduled to receive general anaesthesia with tracheal intubation were enrolled after permission from institutional committee. RHTMD, modified Mallampati test, sterno-mental distance, inter-incisor distance and upper-lip bite test wereassessed pre-operatively by a single examiner trained in the airway indices but not involved in laryngoscopy. On the day of surgery, laryngoscopy was performed by a trainee anaesthesiologist with minimum two years of experience who was blinded to the airway indices noted by the examiner preoperatively. The Cormack-Lehane grading and subsequent difficulty in intubation as per Intubation difficult scale was noted. RHTMD≥23.5, inter-incisor distance ≤ 4 cm, sterno-mental distance ≤12.5 cmand upper lip bite test class 3 were considered as predictor of difficult laryngoscopy. ResultsThe incidence of DVL and difficult intubation in our study was 6.57% (4.85 %-8.82%, 95% CI) and 1.37% (0.68%–2.7%, 95% CI) respectively. The sensitivity of RHTMD, modified Mallampati test, sterno-mental distance, inter-incisor distance and upper-lip bite test were 65.12%, 53.49%, 18.6%, 30.23% and 72.09% respectively. Specificity of RHTMD, modified Mallampati test, sterno-mental distance, inter-incisor distance and upper-lip bite test was 90.51%, 90.34%, 97.22%, 98.20%, and 89.69% respectively. Area under the ROC curve was highest for RHTMD (0.881). Area under the ROC curve for modified Mallampati test, sterno-mental distance, inter-incisor distance and upper-lip bite test was 0.742, 0.621, 0.757 and 0.815 respectively. RHTMD had a sensitivity, specificity, and AUC for predicting difficult intubation of 66.67%, 87.60%, and 0.908 respectively. ConclusionWe primarily conclude that RHTMD has a good predictive performance and is similar to modified Mallampati test as a predictor of difficult visualization of larynx. We secondarily conclude that RHTMD is a better predictor of difficult visualization of larynx compared to sterno-mental distance, inter-incisor distance and upper-lip bite test. It is also an excellent predictor of IDS> 5.

Analysis of various airway evaluation tests to prognosticate difficult endotracheal intubation

Background: Unanticipated difficult intubation or failure of intubation is a major source for anesthesia associated deaths. Hence pre-anesthetic checkup should include a detailed airway evaluation to foresee difficult endotracheal intubation. Some easy bedside tests to predict difficult airway include modified Mallampati test (MMT), ratio of height to thyromental distance (RHTMD), and upper lip bite test (ULBT). Actual difficulty of airway can be estimated using Cormack Lehane (CL) grading while performing laryngoscopy. Combination of two or more bedside clinical tests is used to identify difficult airway and act accordingly. Aims and Objectives: We aimed at identifying those airway assessment tests which best predicted difficult airway. The objectives were to determine the agreement between MMT, RHTMD, ULBT with CL grading, and also the agreement between MMT and ULBT, MMT and RHTMD. Materials and Methods: This observational research was done in 88 individuals between 18 and 75 years planned for elective procedures requiring endotracheal intubation as a part of general anesthesia. The clinical assessment tests such as ULBT, RHTMD, and MMT were done on eligible participants during pre-anesthetic check-up. In the operation theater, patient was prepared, premedicated, and induced. CL grading was used to assess the laryngoscopic view. We tried to determine the agreement between MMT, ULBT and RHTMD with CL grading. We also tried to determine the agreement between MMT and ULBT., MMT and RHTMD. Results: MMT showed moderate, RHTMD showed slight, and ULBT showed no agreement with CL grading. MMT showed highest sensitivity and RHTMD showed highest specificity. No agreement was found for ULBT and RHTMD with MMT. Conclusion: MMT and RHTMD can be used in predicting difficult airway access; out of which MMT is better than RHTMD. ULBT is not an ideal test to identify difficult endotracheal intubation. Laryngoscopic view becomes difficult with increase in weight and age.

Prediction of Difficult Endotracheal Intubation by Different Bedside Tests

Background: An incidence of difficult intubation in elective surgery is 1.5%–8%. Multiple attempts during tracheal intubation can cause airway injuries bleeding, brain hypoxia, and even cardiac arrest. Unanticipated failure and inability to secure difficult airway can lead to “cannot ventilate, cannot intubate” condition. Preoperative assessment and bedside tests play a vital role in predicting and stratifying risk of difficult intubation. This study was done to determine the incidence of difficult intubation and diagnostic accuracy of different bedside tests for predicting intubation difficulty in patients without airway pathology scheduled for elective surgery under general anesthesia. Materials and Methods: Two hundred patients, aged 20–50 years, American Society of Anaesthesiologists I and II, without airway pathology undergoing elective surgery were evaluated preoperatively using simple bedside tests such as Mallampati grading (MPG), interincisor gap (IIG), thyromental distance (TMD), sternomental distance, upper lip bite test, neck circumference, and atlantooccipital extension to predict difficult intubation. Statistical confirmation was done using Pearson’s chi-square test and univariate and multivariate logistic regression. Results: In our study, the incidence of difficult intubation was observed as 6%. High sensitivity for predicting difficult intubation was seen with IIG &gt; TMD &gt; MPG, and high specificity among the relevant bedside tests was seen with TMD &gt; MPG &gt; IIG. Tests with high positive predictive value were TMD &gt; MPG, whereas high negative predictive value was seen with IIG &gt; TMD &gt;MPG. Conclusion: IIG, TMD, and MPG can be used to predict difficult intubation in patients without airway pathology.

EVALUATION OF AIRWAY INDICES FOR PREDICTING DIFFICULTY IN ENDOTRACHEAL INTUBATION IN PATIENTS WITH DIABETES MELLITUS

Background:The need to predict potentially difcult tracheal intubation has received more importance but with limited success. The present study was conducted to assess various airway evaluation indices used to predict difcult airway in Indian patients with diabetes mellitus. Methods: This prospective, observational study was carried out in 85 patients at a tertiary care hospital in Western India. All patients underwent thorough airway assessment using modied Mallampati classication, mouth opening, upper lip bite test, thyromental distance, head extension, palm print, prayer sign and body mass index. Preoperative data of the various airway indices were co-related with difcult intubation to evaluate the sensitivity, specicity, positive predictive value and negative predictive value of each test. Results: Overall, the best indicator to predict difcult intubation in patients with diabetes was the palm print (58.7% sensitive; 94.9% specic; 75.3% accurate) followed by Mallampati score (50% sensitive; 94.9% specic; 70.6% accurate) and prayer sign (54.3% sensitive; 89.7% specic; 70.6% accurate). There was a signicant association between prediction of difcult intubation and occurrence of complications during intubation in patients with diabetes. Conclusion: Even though all airway indices have their place in an anesthesiologists' armamentarium, the palm print is an ideal predictor of difcult intubation in patients with diabetes, followed by the Mallampati score and the prayer sign.

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

BackgroundMaintaining 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.MethodsA 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.ResultsThe 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.ConclusionThe 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 the reliability of the upper lip bite test and the modified mallampati test in predicting difficult intubation under direct laryngoscopy in apparently normal patients: a prospective observational clinical study

Background and aimsDifficult endotracheal intubation is one of the most challenging operations in anesthesia. How to better predict difficult airway and make corresponding preparations to reduce the occurrence of accidents is a difficult task faced by anesthesiologists every day. This study decide to evaluate the value of the Upper Lip Bite Test (ULBT) and the Modified Mallampati Test (MMT) in predicting difficult intubation under direct laryngoscopy and find out the most intuitive and simple method to predict difficult intubation under direct laryngoscopy in apparently normal patients.Patients and methodsThis descriptive-analytical study was performed on 450 patients for elective surgery under general anesthesia requiring endotracheal intubation. The ULBT and MMT grading were evaluated preoperatively and Cormack and Lehane’s (CL) classification was recorded on the day of surgery during intubation under direct laryngoscopy. The accuracy, sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), likelihood ratio (LR), Youden index and area under ROC curve of ULBT and MMT respectively and in combination were calculated and compared. And the consistency between the total scores of ULBT and MMT combined in different ways and CL grading was counted.ResultsOf the 450 patients, 69 (15.3%) were classified as difficult cases of direct laryngoscopy. The accuracy, sensitivity, specificity, PPV and NPV of ULBT were 81.33, 11.59, 93.96, 25.81, 85.44%; and those the corresponding values for MMT were 66.22, 62.32, 69.29, 26.88 and 91.03%. A combination of ULBT and MMT did not improve the sensitivity in the sample tested. The combined total scores of ULBT and MMT in both ways were less consistent with CL grading in predicting difficult intubation under direct laryngoscopy.ConclusionBased on findings of current study, we conclude that ULBT and MMT for difficult intubation have only poor to moderate discriminative power when used alone.The combination of the two tests in fractional form is also not a good predictor of difficult intubation under direct laryngoscopy.Trial registrationChinese Clinical Trial Registry, ChiCTR2100052987, Registered 07 November 2021, http://www.chictr.org.cn

The effect of first trimester body mass index on the changes in the upper lip bite test classification before and after delivery: A prospective observational study.

BackgroundThe difficult airway (DA) assessment and management of pregnant woman has always brought specific challenges. The aim of this study was to investigate the effect of labor on the airway by assessing changes in the upper lip bite test (ULBT) classes and to explore its correlation with the first trimester's body mass index (BMI).MethodsAccording to the BMI of the first trimester, 354 full-term women were divided into low BMI group, normal BMI group and high BMI group. The ULBT class and pregnancy outcome were recorded and compared at early labor, after delivery, and 48 h after delivery.ResultsThe ULBT class was increased in 75(21.1%) patients after delivery. Compared to the normal BMI group, the high BMI group had a higher probability of increasing (34.8 vs. 17.5%; P = 0.002). The number of women with ULBT class 2–3 increased to 157, which was 1.48 times that of early labor. The number of women with ULBT class 3 increased from 4 to 16, of which 7 (53.8%) were from the high BMI group. Binary logistic regression analysis showed that first trimester's BMI was associated with a significant increase in ULBT class after delivery (adjusted odds ratio [aOR] = 2.13 [0.91–4.98], P = 0.02). The ULBT classes of the three groups tended to return to their initial level 48 h after delivery (P > 0.05).ConclusionLabor results in an approximately one-fifth increase in ULBT class. Being overweight or obese in the first trimester is associated with an increased risk of DA during labor.Trial registrationThis study was registered in the Chinese Clinical Trial Registry (http://www.chictr.org.cn) on September 26, 2020. Registration number ChiCTR2000038643.