Hyomental Distance Ratio Research Articles

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.
 Objective : To compare the various clinical and ultrasonographic parameters in predicting difficult airway.
 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.
 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.
 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.

Clinical and ultrasonographic assessment of airway indices among non-pregnant, normotensive pregnant and pre-eclamptic patients: a prospective observational study

BackgroundPrediction of a difficult airway is of paramount importance for an anaesthesiologist. Various anatomical and physiological factors contribute to a difficult airway in pregnant females, especially those with pre-eclampsia. The aim of the study was to assess airway indices using both routinely used clinical methods and ultrasound. MethodsFifty-five non-pregnant females, 55 normotensive pregnant females and 55 females with pre-eclampsia were included in this prospective study. Clinical airway assessment was the modified Mallampati score, thyromental distance, hyomental distance, hyomental distance ratio, chest circumference, neck circumference and chest-to-neck circumference ratio. Sonographic assessment included tongue width, tongue volume, anterior neck soft tissue thickness at the level of hyoid, epiglottis and vocal cords, subglottic diameter, ratio of pre-epiglottic space to anterior, posterior and midpoint of anterior and posterior vocal folds. ResultsSeveral significant differences were observed between pregnant and non-pregnant females, with additional changes in pre-eclamptic females. These included clinical parameters such as the modified Mallampati score and sonographic measurements of tongue width, tongue volume, subglottic diameter, anterior neck soft tissue thickness at the level of hyoid, epiglottis and vocal cords, and the ratio of pre-epiglottic space to anterior, posterior and midpoint of anterior and posterior vocal folds. ConclusionRoutinely used clinical methods of airway assessment lack sensitivity and specificity. Ultrasound can visualise anatomical structures in the supraglottic and subglottic views and is encouraging as an airway assessment tool.

Diagnostic Accuracy of Hyomental Distance Ratio (HMDR) for Prediction of Difficult Laryngoscopy in Patients Undergoing Surgery Under General Anesthesia Using Tracheal Intubation

Background: To keep the airway open, a flexible plastic tube (ETT) is inserted into the trachea during tracheal intubation. Even when done correctly, tracheal intubation requires much clinical experience, and catastrophic problems can occur. Mandibular space has been estimated using hyomental distance (HMD), although HMD has only been found to provide a limited amount of diagnostic accuracy on its own. In order to determine how well the Hyomental Distance Ratio (HMDR) predicts difficult laryngoscopy, we conducted this study. Objectives: Using the Cormack and Lehane classification as the gold standard, the objective is to assess the diagnostic validity of the Hyomental Distance Ratio (HMDR) for the prediction of challenging laryngoscopy in patients undergoing surgery under general anaesthesia. Materials &amp; Methods: The department of anesthesiology and the general surgery operating rooms at Sir Ganga Ram Hospital in Lahore conducted this cross-sectional study over the course of six months in 2015–2016. The approach of non-probability purposive sampling was applied. Informed consent was acquired, and patient demographics were recorded. The researcher herself then assessed patients for HDMR. In order to determine if a patient had a difficult or normal laryngoscopy, HDMR was determined. After that, the researcher performed a laryngoscopy on the patients. If the vocal cords were visible, the mouth was opened, and the case was assessed using the Cormack and Lehane classification (CL), with easy or difficult laryngoscopy being designated. SPSS version 20 was used to enter and analyse all of the data. Results: The patients in our study had a mean age of 43.23 11.63 years and a male to female ratio of 1.5:1. In this study, 43.91% of patients had an HDR difficult intubation. HDR's difficult intubation has a sensitivity of 95.05%, a specificity of 96.12%, and a diagnostic accuracy of 95.65% when using CL as the gold standard. Practical Implication: According to this study, this strategy can be applied accurately in other hospitals. Government should establish guidelines for using the most trustworthy techniques as the benchmark in healthcare settings. Conclusion: According to the findings of our study, the HMDR is a viable diagnostic tool for anticipating challenging laryngoscopy in patients having general anaesthesia with tracheal intubation. According to this study, this strategy can be applied accurately in other hospitals. Government should establish guidelines for using the most trustworthy techniques as the benchmark in healthcare settings. Keywords: Laryngoscopy, difficult intubation, Cormack Classification, difficult surgery

Comparative study of sonographic measurement of PRE-E/E-VC ratio versus Hyomental distance ratio to correlate Cormack–Lehane grading for airway assessment

Background: Predicting a difficult airway preoperatively overcomes the hurdles of unanticipated difficult airway management. Cormack–Lehane grading (CL Grading) best describes the view of larynx. However, direct laryngoscopy cannot be used to predict difficult airway for patients undergoing intubation for the 1st time. On the other hand, ultrasound is a safe and painless procedure. This study was done to correlate airway ultrasound findings with CL Grading by direct laryngoscopy. The patients selected were undergoing elective surgeries under general anesthesia. Aims and Objectives: The aims of the present study were to correlate the ultrasound view of the airway with the Cormack–Lehane classification by direct laryngoscopy. Materials and Methods: A group of 94 patients, aged 18–60 years, ASA I/II were selected who underwent elective surgical procedures under general anesthesia requiring intubation by direct laryngoscopy. Pre-epiglottic (PRE-E) depth and epiglottic vocal distance (E-VC) were measured along with hyomental distance ratio (HMDR) by ultrasound. The ultrasound parameters were then compared with CL Grading during laryngoscopy. Results: The PRE-E depth/epiglottic vocal cord distance correlated better than hyomental distance ratio in predicting CL Grading (P=0.000). Conclusion: The PRE-E/E-VC ratio was a better predictor of CL Grading than the HMDR.

Preoperative ultrasonographic prediction of difficult airway in patients undergoing surgery under general anaesthesia

Background: Preoperative assessment of the airway with ultrasound has come up as a viable option to aid the preanaesthetic airway assessment. Objectives: To identify reliable ultrasound parameters as predictors of difficult airway in patients undergoing surgery under general anaesthesia. Methods: A prospective analytical cross-sectional study was conducted at Kathmandu Medical College in 99 consecutive patients scheduled for elective surgery with general anaesthesia and endotracheal intubation from July 2019 to June 2020 after ethical clearance. Three ultrasound parameters were used for this study. Distance from the skin to the anterior aspect of trachea at the level of vocal cords (ANS-VC), the depth of the pre-epiglottic space (PreE), the distance from the epiglottis to the midpoint of vocal cords (EVC) was measured. The PreE/EVC and hyomental distance ratio (HMDR), which is the distance ratio of hyomental distance at neutral and extended head position were calculated. These ultrasonographic parameters were used to predict difficult laryngoscopy Cormack-Lehane (CL) grading 3, 4. Results: Difficult intubation was seen in 23 (23.2%) as CL grade 3. The authors did not encounter CL grade 4. HMDR and PreE/EVC have been shown to have significant association with CL grading, with a specificity of 71% and 77% respectively and a high negative predictive value of 84.3% and 84.2% respectively. Therefore, it is valuable in predicting difficult intubation. ANS-VC did not have a significant correlation. Conclusion: Diagnostic predictability of difficult airway is better with HMDR and PreE/E-VC.

Prediction of the Difficult Laryngoscopy with Ultrasound Measurements of Hyomental Distance

Abstract Ultrasound measurement of hyomental distance is promising as a predictor for difficult laryngoscopy in cases of difficult airway management. The aim of the study was to evaluate the prognostic value of ultrasound measurement of hyomental distance (HMD) for prediction of difficult laryngoscopy. Hyomental distance was sonographically measured in neutral (HMDn) and extreme head extension (HMDe) positions for fifty-six patients scheduled for elective surgery requiring tracheal intubation. Then the hyomental distance ratio (HMDR) was calculated. According to presence of difficult laryngoscopy assessed by the Cormack–Lehane (CL) score, patients were divided into a difficult laryngoscopy group (DL, n = 15) and easy laryngoscopy group (EL, n = 41). We calculated the sensitivity and specificity of HMDn, HMDe, and HMDR for difficult laryngoscopy. DL was present in 15 (27%) patients. We found a significant intergroup difference in HMDR between the DL and EL groups (1.12 ± 0.04 vs. 1.24 ± 0.06, respectively; p &lt; 0.001). In contrast, we were not able to find a significant difference for HMDn and HMDr. HMDR had the highest sensitivity 86.7% and specificity 85.4% (p &lt; 0.01) to predict difficult laryngoscopy, where the area under the curve was 0.939; p &lt; 0.01 for HDMR &lt; 1.2 cm. Moreover, we found that difficult laryngoscopy was associated with higher body mass index (BMI), with higher values in the DL group compared to EL patients (34.3 ± 9.1 vs. 28.5 ± 5.7 kg/m2, respectively; p = 0.035). HMDR &lt; 1.2 cm measured by ultrasound might have a good predictive value for prediction of difficult laryngoscopy.

A Cross-Sectional Study on Hyomental Distance Ratio (HMDR) as a New Predictor of Difficult Laryngoscopy in ICU Patients.

Background: Intubation in the ICU is sometimes unpredictable unlike in an operation theatre, where pre-anesthetic assessment for airway has been done. This study has been done to evaluate the usefulness of hyomental distance ratio (HMDR) in accurately predicting difficult laryngoscopy in ICU patients.Methods: In this study, 104 critically ill patients in the age group 18-70 years, undergoing tracheal intubation in ICU were included. A hard plastic ruler was pressed on the skin surface just above the hyoid bone and the distance to the tip of the anterior-most part of the mentum measured was defined as hyomental distance (HMD). HMD was assessed in neutral and extended head positions, and the HMDR was calculated. All patients were sedated, pre-oxygenated, induced, and relaxed prior to glottic visualization by direct laryngoscopy, which was performed by an experienced anesthetist. Cormack-Lehane's (CL's) grade was assessed without external laryngeal manipulation. Further management was as per ICU protocol.Results: Using the Chi-Square test for statistical analysis, a p-value of HMDR in assessing difficult laryngoscopy was found to be <0.001 suggesting strong significance. HMD in the extended head position (HDMe) showed moderate significance with a p-value of 0.047. HMDR <1.2 can be considered a clinically reliable individual predictor of difficult laryngoscopy in ICU patients.Conclusion: HMDR <1.2 can be used as a simple, easy, and reliable bedside test to predict difficult laryngoscopy amongst ICU patients. An optimal combination of tests is suggested if feasible for better accuracy.

Performance of Ultrasound Based Quantification of Hyomental Distance Ratio in Predicting Difficult Airway in Anaesthesia

Performance of Ultrasound Based Quantification of Hyomental Distance Ratio in Predicting Difficult Airway in Anaesthesia

Comparison of Different Ultrasound Parameters for Airway Assessment in Patients Undergoing Surgery under General Anaesthesia.

The aim of this study was to evaluate and correlate ultrasound measurement of airway parameters with the Cormack- Lehane (CL) grading observed under direct laryngoscopy for prediction of difficult airway. This prospective, observational study was conducted in a tertiary care institute. Ninety-six patients were scheduled for elective surgery under general anaesthesia and tracheal intubation. They were categorised as having easy (CL grades 1, 2a, and 2b) or difficult (CL grades 3a, 3b, and 4) laryngoscopy. The sonographically measured airway parameters included anterior neck soft tissue thickness at vocal cord level (ANS-VC), hyomental distance ratio (HMDr), and tongue volume (TV). These parameters were compared and correlated with the CL grading. The statistical analysis was done using SPSS version 21.0. Difficult laryngoscopy was observed in 17.7% patients. Significant difference was noted in ANS-VC 0.28 6 0.09; 0.39 6 0.12, (P < .0001) and HMDr, 1.2 6 0.09; 1.15 6 0.13, (P ¼ .006) for easy and difficult laryngoscopy, respectively. ANS-VC had a sensitivity of 78.9% and specificity of 71.1% (AUC-0.816) followed by HMDr (AUC-0.713) and TV (AUC-0.608). Combined ultrasound parameters had significantly higher AUC value (0.867). ANS-VC was the most significant parameter with a value of >0.29 cm being a sensitive predictor of difficult intubation. Combined sonographic parameters (ANS-VC, HMDr, and TV) were better predictors of difficult intubation.

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

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. One hundred ninety-six 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. 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. 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.

Ultrasonography indicators for predicting difficult intubation: a systematic review and meta-analysis

BackgroundUltrasonography (US) is recently used frequently as a tool for airway assessment prior to intubation (endotracheal tube (ETT) placement), and several indicators have been proposed in studies with different reported performances in this regard. This systematic review and meta-analysis reviewed the performance of US in difficult airway assessment.MethodsThis systematic review and meta-analysis was conducted according to the guideline of Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) and the Cochrane book. All the studies that had carried out difficult airway assessments using US, had compared the indicators in difficult and easy groups, and had published the results in English by the time we conducted our search in April 28, 2020, were included.ResultsIn the initial search, 17,156 articles were retrieved. After deleting the duplicate articles retrieved from multiple databases, 7578 articles remained for screening based on the abstracts and titles. Finally, the full text of 371 articles were assessed and the data from 26 articles were extracted, which had examined a total of 45 US indicators for predicting difficult intubation. The most common US index was the “thickness of anterior neck soft tissue at the vocal cords level”. Also, “skin to epiglottis” and “anterior neck soft tissue at the hyoid bone level” were among the most common indicators examined in this area.ConclusionThis systematic review showed that US can be used for predicting difficult airway. Of note, “skin thickness at the epiglottis and hyoid levels”, “the hyomental distance”, and “the hyomental distance ratio” were correlated with difficult laryngoscopy in the meta-analysis. Many other indicators, including some ratios, have also been proposed for accurately predicting difficult intubation, although there have been no external validation studies on them.

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

BackgroundAirway 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.MethodsWe 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.ResultsUnivariate 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).ConclusionsC2C6AR 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 registrationThe study was registered at the Chinese Clinical Trial Registry (http://www.chictr.org.cn; identifier: ChiCTR-ROC-16,008,598) on June 6, 2016.

English

BACKGROUND A few patients of apparently normal appearance unexpectedly present with great difficulties during intubation which may lead to potentially serious consequences. Thus, we worked on this area with the aim to determine the ability to predict difficult visualisation of larynx using the following preoperative airway predictors: MMC (Modified Mallampati Classification), RHSMD (Ratio of Height to Sternomental Distance), RHTMD (Ratio of Height to Thyromental) and HMDR (Hyomental Distance Ratio) and comparison of these with WRSS (Wilson Risk Sum Score), in isolation and in combination. METHODS A double-blind, prospective study was carried out on 300, ASA grade I or II patients posted for elective surgery in supine position under general anaesthesia. Different parameters were recorded in pre-op period and Cormack-Lehane grading and difficulty of intubation was recorded at the time of intubation. Chi Square test and receiver operating curve were used to assess the association of all the airway tests and various combinations with CL grading. Cohen’s kappa was calculated to determine the strength of agreement between laryngoscopy grade and various tests in isolation and combinations. RESULTS In our study, highest strength of agreement was found with WRSS of 0.925 (0.873 - 0.976) and only a fair agreement was seen with HMDR (κ = 0.319). RHSMD and combination of RHSMD + MMC showed good strength with kappa of 0.638 and 0.634 respectively. CONCLUSIONS No single test or group of tests was able to predict all cases of difficult laryngoscopy at the preoperative airway assessment. Wilson Risk Sum Score was found to be the best predictor of difficult laryngoscopy when compared to MMC, RHTMD, RHSMD and HMDR in isolation and any possible combination. KEYWORDS Difficult Laryngoscopy, Difficult Intubation, Wilson Risk Sum Score, Airway, RHSMD, RHTMD

Clinical versus Ultrasound Measurements of Hyomental Distance Ratio for the Prediction of Difficult Airway in Patients with and without Morbid Obesity.

Purpose: To describe the correlation between clinically measured hyomental distance ratio (HMDRclin) and the ultrasound measurement (HMDRecho) in patients with and without morbid obesity and to compare their diagnostic accuracy for difficult airway prediction. Methods: HMDRclin and HMDRecho were recorded the day before surgery in 160 consecutive consenting patients. Laryngoscopy was performed by a skilled anesthesiologist, with grades III and IV Cormack–Lehane being considered difficult views of the glottis. Linear regression was used to assess the correlation between HMDRclin and HDMRecho and receiver operating curve analysis was used to compare the performance of the two for predicting difficult airway. Results: The linear correlation between HMDRclin and HDMRecho in patients without morbid obesity had a Pearson coefficient of 0.494, while for patients with morbid obesity this was 0.14. A slightly higher area under the curve for HMDRecho was oberved: 0.64 (5%CI 0.56–0.71) versus 0.52 (95%CI, 0.44–0.60) (p = 0.34). Conclusion: The association between HMDRclin and HDMRecho is moderate in patients without morbid obesity, but negligible in morbidly obese patients. These might be explained by difficulties in palpating anatomical structures of the airway.

Comparative Study of Preoperative Airway Assessment by Conventional Clinical Predictors and Ultrasound-Assisted Predictors.

Aims:The aim of this study is to evaluate the effectiveness of airway sonographic parameters as the predictors of difficult laryngoscopy and to evaluate the validity of combined sonographic and clinical tests.Materials and Methods:This prospective and observational study analyzed a sample of 200 patients who were categorized as having easy (Grades 1 and 2) or difficult (Grades 3 and 4) laryngoscopy based on the laryngoscopic criteria of Cormack-Lahane (CL). Sonographic parameters, including the anterior neck soft-tissue thickness at the level of vocal cord (ANS-VC), ANS tissue thickness at the level of hyoid, and ratio of depth of pre-epiglottic space to distance from epiglottis to midpoint of the distance between vocal cords and clinical parameters, including modified Mallampati class, thyromental distance, and hyomental distance ratio (HMDR), were analyzed. Univariate and multivariate regression analysis was used for the statistical analysis.Results:Twenty patients (10%) were categorized as having difficult laryngoscopy. Statistically significant differences between patients with difficult and easy laryngoscopy were noted for 5 of 6 parameters. The diagnostic validity profiles showed variable sensitivity (26.5%–87.5%) and good specificity (58.9%–94.2%) and negative predictive value (88.8%–97.03%). ANS-VC has the highest sensitivity (87.50%) and area under curve value (0.887), whereas HMDR showed highest specificity (94.2%) and highest accuracy (89.60%) which means it has low false-positive prediction rate. The combination of tests improved the diagnostic validity profile (highest area under the curve, 0.897).Conclusion:Sonographic predictors can help in identifying difficult laryngoscopy. Combined clinical and ultrasonographic parameters showed better validity profiles in comparison to the individual tests.

Diagnostic Value of Upper Lip Bite Test combined with Hyomental Distance Ratio in assessing the airway

INTRODUCTION Airway assessment before any type of anesthesia is mandatory. Upper lip bite test (ULBT) is a relatively new test for assessing the airway. Range of freedom of mandible and dental architecture has a significant role in facilitating intubation, both of which are assessed by this single test. ULBT with good neck movements are sufficient criteria for assessing the airway. Hyomental distance ratio (HMDR) assesses the range of neck movements. So by combining these two tests we expect an increase in reliability and validity. METHODS Preoperatively we assessed the airway using ULBT, HMDR, and Mallampati (MP) tests of 300 patients. The anesthesiologist doing laryngoscopy is blinded to the results of pre op airway evaluation. Direct laryngoscopies are graded using the modified Cormack and Lehane scale. Difficult laryngoscopy was defined as Grade 3 or 4 view. ULBT class 3, and HMDR with optimal cutoff point 1.2 are considered as difficult intubation predictors. Sensitivity, Specificity, Positive Predictive Value (PPV), Negative Predictive Value (NPV) and Accuracy of both ULBT and HMDR separately and then both in combination are calculated and compared with those of MP. RESULTS ULBT:-Sensitivity - 88.2%, Specificity - 99.62%, PPV - 96.77%, NPV - 98.51%, Accuracy - 98.33% HMDR: - Sensitivity - 88.2%, Specificity – 99.25%, PPV - 93.75%, NPV - 98.50%, Accuracy - 98.00% MP: - Sensitivity - 17.65%, specificity - 88.72%, PPV - 16.67%, NPV - 89.39%, Accuracy - 80.66% ULBT+HMDR: - Sensitivity - 82.35%, specificity-100%, PPV100%, NPV97.75%, Accuracy - 98.00 % CONCLUSION Upper Lip Bite test is good screening test for assessing the airway. ULBT in combination with HMDR increased the specificity and positive predictive value.

TO MEASURE THE CORRELATION BETWEEN ULTRASONOGRAPHY MEASURED HYOMENTAL DISTANCE RATIO AND EASE OF LARYNGOSCOPY

Background: Difficult and failed tracheal intubation after direct laryngoscopy is a dreaded complication of general anesthesia as it is associated with serious morbidity and mortality.&#x0D; Methods: Prospective Observational conducted at Department of Anesthesiology, Dr. RPGMC Kangra at Tanda, Himachal Pradesh.&#x0D; Results: In the present study, the mean hyomental distance ratio was (mean±SD:1.1.±.127 and 1.04±.018) in predicting CL grade 3 and 4 respectively (P=0.010) and 1.12±.033, 1.11±.035 in grade 1 and 2 respectively.&#x0D; Conclusion: Ultrasound is better and fast in confirming endotracheal intubation.&#x0D; Keywords: Ultrasound, endotracheal intubation, direct laryngoscopy.

The usefulness of point of care ultrasound (POCUS) in preanaesthetic airway assessment.

Background and Aims:Point of care ultrasound has the potential to become reliable airway assessment tool by accurate prediction of difficult laryngoscopy. We aimed to determine the feasibility of ultrasound in preoperative airway assessment.Methods:This prospective, observational study was conducted on 200 patients requiring general anaesthesia and tracheal intubation. The thickness of anterior soft tissue neck at the level of hyoid bone (DSHB), epiglottis (DSEM), and Pre-E/E-VC[depth of the pre-epiglottic space (Pre-E)/distance from the epiglottis to the midpoint of the distance between the vocal cords (E-VC)] were measured sonographically. The hyomental distance ratio (HMDR) was measured utilising distances with head in neutral and extended position. The primary outcome was the efficacy of the parameters in predicting difficult laryngoscopy[Cormack Lehane 3,4]. The secondary outcome was to correlate the parameters to CL grading.Results:Utilising receiver operating curves, cutoff value of HMDR for predicting difficult laryngoscopy was ≤1.0870 with sensitivity of 65%, specificity of 77%. The cutoff value, sensitivity andspecificity for Pre-E/E-VC were ≥1.785, 82.8% and 83.8%., respectively. The cutoff value of DSHB was ≥0.99 with sensitivity of 48% and specificity of 82%. The cutoff, sensitivity and specificity for DSEM were ≥1.615, 89.7%, and 64.8%, respectively. There was moderate positive correlations of DSHB, DSEM, and Pre-E/E-VC (r = 0.551 and 0.701, 0.787: P = 0.00), whereas moderate negative correlation observed with HMDR (r = -.0671: P = 0.00).Conclusion:The strong positive correlation of Pre-E/E-VC, DSEM, and moderate negative correlation of HMDR makes these ultrasound parameters reliable predictors for difficult laryngoscopy.

Identification of Patients With the Risk for Difficult Tracheal Intubation in the Intensive Care Unit

Background: Aims: Identification of patients at risk for difficult visualization of the larynx (DVL) using Hyomental distance ratio (HMDR) in adopting an alternative strategy for intubation at intensive care unit. Settings and Design: Haemodynamicaly stable unconscious patients with GCS &lt;8 admitted in intensive care unit requiring intubation. &nbsp;Subjects and Methods: A scale was put on to the surface on the skin near to&nbsp; hyoid bone, and distance from point near mentum to&nbsp; hyoid bone measured and was taken as the Hyo-mental distance (neutral position) and measurement&nbsp; taken by extension method and ratio&nbsp; calculated. After intravenous induction followed by paralysis,vocal cords were visualised&nbsp; and assessed with Cormach and Lehane method (C&amp;L) classification. Statistical analysis: Done using students ‘t’ test and chi-square test. Results: The highest sensitivity 26.30% observed in predicting DVL was with HMDR (26.30%). Conclusion: HMDR is a good and reliable predictor of DVL to certain extent , because of its higher specificity and negative predictive value.