Prediction Of Difficult Intubation Research Articles

Evaluation of neck-circumference- thyromental- distance ratio as a predictor of difficult intubation: A prospective, observational study.

Preoperative identification of difficult airway and subsequent planning is of utmost importance for a patient's safety. Previous studies have identified the ratio of the neck circumference (NC) to the thyromental distance (TMD); NC/TMD as a reliable predictor of difficult intubation in obese patients. But there is a lack of studies evaluating the NC/TMD in non-obese patients. Therefore, the aim of this study was to compare the NC/TMD as a predictor of difficult intubation in both obese and non-obese patients. A prospective, observational study was conducted after obtaining institutional ethics committee clearance and written and informed consent from each patient. One hundred adult patients undergoing elective surgeries under general anaesthesia with orotracheal intubation were included in this study. Difficulty in intubation was assessed using the Intubation Difficulty Scale. The NC/TMD was calculated and the predictive accuracy of NC/TMD and other established parameters in obese and non-obese patients were compared. Univariate logistic regression analysis showed that gender, weight, body mass index, inter-incisor gap, Mallampati classification, NC, TMD, sternomental distance, and NC/TMD had a significant association with difficult intubation. NC/TMD has a higher sensitivity, specificity, and positive and negative predictive value with better predictability in comparison to other parameters. The NC/TMD is a reliable and better predictor of difficult intubation in both obese and non-obese patients in comparison to NC, TMD, and sternomental distance alone.

Pre-epiglottic Space and Epiglottis to Vocal Cord Ratio in Order to Predict Difficult Intubation in Adults: A Multivariate Analysis

Objective: We aimed to enhance the prediction of difficult intubation by using ultrasonographic parameters (pre-epiglottic space (Pre-E), distance between epiglottis to middle part of vocal cord (E-VC) and Pre-E/E-VC) adjusting for traditional airway assessments. Material and Methods: This prospective cohort study was conducted at a super-tertiary care hospital in Thailand. Participants aged 18-65 years with ASA classification I-III and who required general anesthesia with endotracheal intubation were included. Preoperative traditional and ultrasonographic airway assessments were performed by two investigators. The outcome was difficult intubations as diagnosed by laryngoscopic view grade 3 or 4. Multivariate logistic regression was used to identify predictors for difficult intubation presented by adjusted odds ratio (OR) and 95% confidence interval (CI). Results: A total of 94 patients were recruited. The incidence of difficult intubation was 15%. The median Pre-E/E-VC ratio among this group was 0.8 compared with 1.0 in the control group (p-value 0.124). The cut-off point of <1.0 of Pre- E/E-VC was not associated with difficult intubation after adjusting for sex and other traditional parameters (p-value 0.11). Predictors of difficult intubation were female sex (OR [95% CI]: 13.8 [2.8, 68.3]), sternomental distance ≤175 mm (OR [95% CI]: 11.6 [1.9, 71.4]) and interincisor gap <4 cm (OR [95% CI]: 19.8 [1.1, 373.8]) with the area under the receiver operating characteristic curve at 0.88 and a specificity of 90.0%. Conclusion: There was no association between the Pre-E/E-VC in predicting difficult intubation in low-risk patients. The ultrasonographic measurements of Pre-E/E-VC were not helpful in predicting difficult intubations in our setting. Trial registration: thaiclinicaltrials.org: TCTR20180115002, Registered 9 January 2018 - Prospectively registered, https:// www.thaiclinicaltrials.org/#

Airway assessment: Predictors for difficult intubation – A prospective observational study

Airway management remains an important challenge in the contemporary practice of anaesthesia and preoperative airway assessment facilitates appropriate preparation when difficulty with intubation or ventilation is anticipated prior to induction of anaesthesia.: Aim: To study the important predictors for difficult laryngeal intubation. To determine the predictors of difficult laryngeal intubation. Secondary: To determine the most significant predictor for difficult intubation and to determine the incidence of unanticipated difficult intubation.This single centre prospective observational study done in Bangalore Baptist hospital (after obtaining clearance from ethical committee) included adult patients posted for elective surgeries who received general anaesthesia. Patients of either gender in the 18 – 65 year age group, with an American Society of Anaesthesiologists physical status classification of I or II, who required endotracheal intubation for general anaesthesia. The sample size was 413 with confidence level 95%. In our study the sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of Mallampati class were found to be 75.8%, 78.06%, 37.90%, 94.80% respectively. The sensitivity, specificity, PPV and NPV of mouth opening were found to be 33.87%, 81.19%, 24.13%, 87.42% respectively. The sensitivity, specificity, PPV and NPV of upper lip bite test found to be 27.41%, 96.29%, 56.66%, 88.25% respectively. The sensitivity, specificity, PPV and NPV of neck extension found to be 54.83%, 92.59%, 56.66%, 92.06% respectively. The sensitivity, specificity, PPV and NPV of BMI found to be 53.22%, 75.49%, 27.73%, 90.13% respectively. The incidence of difficult intubation was 15%.:In conclusion, no single predictor is sufficient for prediction of difficult intubation on its own. All the studied bedside tests are poor to moderate predictors of difficult intubation. All the tests showed poor positive predictive values and high negative predictive values which suggests that they can be more useful predictors of easy intubation than difficult intubation.

Are the HEAVEN criteria reliable as a predictive tool for emergency airway management? A systematic review

Background: Airway management is one of the most vital skills used by advanced airway providers. Anticipating a difficult airway is crucial for the risk-benefit analysis and may help providers to determine the optimal airway management approach. Existing difficult airway assessment tools may have limited application in emergency airway management. In addition, these do not incorporate physiological factors. More recently, Davis and Olvera proposed the HEAVEN criteria as a novel difficult airway predictive tool for emergency airway management. The objective of this study is to review HEAVEN as a novel airway prediction tool. Material and Methods: This systematic review was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. Results of a comprehensive search in three major databases, as well as hand searching, were screened in title/abstract and full-text stages. We included the journal articles which review HEAVEN as a novel airway prediction tool with both retrospective and prospective study designs. The population included patients requiring rapid sequence intubation (RSI) or delayed sequence intubation (DSI). Two investigators independently extracted the data with an electronic table in Microsoft Word. Due to the heterogeneity in included study designs, settings, methods, study outcomes, and measurement of the studies, we did not carry out a meta-analysis. The risk of bias (RoB) was assessed using Joanna Briggs Institute checklist. Results: Out of 103 records, only four studies were included. The most cited criterion was the anatomical challenge, which was significantly associated with first-attempt success in three studies. Most studies on HEAVEN did not support physiological factors as predictors of difficult intubation. Two studies reported significant associations between individual HEAVEN criteria and first-attempt success without desaturation. Some included studies reported significant associations between anatomical HEAVEN criteria (extremes of size, anatomical challenge, vomit/blood/fluid, and neck mobility) and difficult airway view. Furthermore, a prospective study reported that hypoxemia and vomit/blood/fluid were significantly associated with intubation complications. Based on the results of the RoB analysis, there wasn’t considerable bias in a great number of included studies. Conclusion: The HEAVEN criteria may represent a development over the traditional approaches. HEAVEN assessment tool considers both physiological and anatomical factors. In addition, all HEAVEN elements can be performed in emergent situations. The HEAVEN criteria seem to be a useful tool to predict difficult airways. There was a variation among studies in the definition of the difficult airway. There is currently no consensus on the definition of a difficult airway, which may explain some of the heterogeneity of the results of this systematic review. Due to the heterogeneity in included studies, we did not carry out a meta-analysis. Therefore, we suggested that future studies should consider homogeneous patient populations, a uniform study design, a matching study setting, and a widely accepted definition of the difficult airway to provide the opportunity to perform meta-analyses. The controversial results of studies highlighted a requirement for more prospective studies with an appropriate study design and considering the possible confounding factors to reach more reliable evidence.

Correlation between upper airway ultrasound and Cormack–Lehane grading during laryngoscopy – A prospective study

Background: Securing airway and adequate ventilation after induction of anesthesia is the utmost priority of anesthesiologists, failure of that can lead to hypoxic brain injury and death in a few minutes. Aims and Objectives: The aims of this study were to ascertain the role of ultrasonography in predicting difficult intubation by comparing different ultrasonographic parameters. Materials and Methods: One hundred patients posted for elective surgery under general anesthesia were studied. The study was carried out in two phases. The first phase – during the pre-anesthetic checkup, ultrasonographic measurements of Anterior neck soft-tissue thickness at the level of hyoid (ANS-Hyoid), anterior neck soft tissue thickness at the level of vocal cords (ANS-VC), pre-epiglottic space (Pre-E), distance from the epiglottis to the mid-point of the distance between the vocal cords (EVL), and the ratio of both (PES/EVL) was also done. In the second phase, Cormack–Lehane (CL) grade was noted during intubation. A Chi-square test was applied to correlate ultrasonographic parameters and CL grade. Sensitivity, specificity, an area under the receiver operating characteristic (ROC) curve, negative predictive value, and positive predictive value were calculated for various parameters. Results: In this study among the studied parameter, only ANS–VC was statistically significant in predicting difficult intubation (P<0.0001). ANS-VC >0.32 cm was 93.3% sensitive and 84.7% specific and had Area under the ROC curve of 85% in predicting CL grade 3 and 4 (difficult intubation). Conclusion: USG is a useful tool in predicting difficult intubation. ANS-VC >0.32 cm is a highly sensitive and specific predictor of difficult intubation, while other USG parameters are not indicative of difficult intubation.

Measurement of Neck Circumference, Tongue thickness and Skin to Epiglottis Distance as Predictors of Difficult Intubation: A Prospective Study

Airway Assessment is essential in pre anesthetic assessment. Anticipating and preparing for difficulty in airway management is crucial to avoid airway catastrophes. Routine pre operative airway examination usually includes mouth opening and dentition, Mallampati classification, thyromental distance and neck movements. Neck circumference is a quick bedside test to determine difficult laryngoscopy. Increased tongue thickness and skin to epiglottis distance affects performance of laryngoscopy and tracheal intubation increasing the risk of difficult airway. Presently there is a search for non-invasive and accurate tools to overcome limitations of clinical airway assessment tests. Ultrasonography has been evolving as a useful device for airway assessment especially soft tissue structures in anterior surface of neck. Here we studied the measurement of neck circumference and ultrasound measurement of tonguethickness and skin to epiglottis distance as predictors for difficult intubation. The Aim of the study is to predict difficulty in intubation by measuring neck circumference, thickness of tongue and thickness of skin to epiglottis. Prospective observational study, 120 patients posted for surgery under general anesthesia, Department of anesthesia, Meenakshi medical college, Kanchipuram. After institutional Human ethical committee clearance, 120 Patients were screened during preoperative assessment for undergoing procedures under general anaesthesia. Neck circumference and other airway parameters were measured with measuring tape and distance between Skin to epiglottis and tongue thickness were measured with ultrasound linear probe. Patients were grouped into Group E( Easy Intubation) whose Cormack-lehane grade was 1 and 2 and Group D ( Difficult intubation) whose Cormack-lehane grade was 3 and 4. SPSS version 16 was used for statistical analysis. There was no statistical significance seen between age, sex, height among easy and difficult intubation but significance was seen with weight (p <0.05), Thyromental distance(p<0.05) and Sterno-mental distance(p<0.05). High significance was seen in Distance between skin to epiglottis distance(p<0.001), Tongue thickness(p<0.001) and Neck Circumference(p<0.001) in difficult intubation cases. Neck circumference and ultrasonographic measurement of tongue thickness and skin to epiglottis can avoid unanticipated difficult intubation.

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 Use of the Shikani Video-Assisted Intubating Stylet Technique in Patients with Restricted Neck Mobility.

Among all the proposed predictors of difficult intubation defined by the intubation difficulty scale, head and neck movement (motility) stands out and plays as a crucial factor in determining the success rate and the degree of ease on endotracheal intubation. Aside from other airway tools (e.g., supraglottic airway devices), optical devices have been developed and applied for more than two decades and have shown their superiority to conventional direct laryngoscopes in many clinical scenarios and settings. Although awake/asleep flexible fiberoptic bronchoscopy is still the gold standard in patients with unstable cervical spines immobilized with a rigid cervical collar or a halo neck brace, videolaryngoscopy has been repeatedly demonstrated to be advantageous. In this brief report, for the first time, we present our clinical experience on the routine use of the Shikani video-assisted intubating stylet technique in patients with traumatic cervical spine injuries immobilized with a cervical stabilizer and in a patient with a stereotactic headframe for neurosurgery. Some trouble-shooting strategies for this technique are discussed. This paper demonstrates that the video-assisted intubating stylet technique is an acceptable alternative airway management method in patients with restricted or confined neck motility.

Predictive Value of Modified Mallampati Test and Upper Lip Bite Test Concerning Cormack and Lehane's Laryngoscopy Grading in the Anticipation of Difficult Intubation: A Cross-Sectional Study at a Tertiary Care Hospital, Bhubaneswar, India.

Background and objectiveMany tests are at hand to predict difficult intubation preoperatively to prevent morbidity and mortality of unanticipated difficult intubation. The present study was conducted to evaluate and compare the efficacy of the modified Mallampati test (MMT) and upper lip bite test (ULBT) to foresee difficult intubation.Materials and methodsAfter obtaining written informed consent, this prospective comparative observational study was conducted on 225 patients scheduled for elective surgery under general endotracheal anesthesia. Preoperative MMT and ULBT were performed. MMT Grade III, IV, and ULBT Grade IV were regarded as predictors of difficult intubation. The laryngoscopic view was graded as per Cormack and Lehane's laryngoscopic grading after induction of anesthesia by an experienced anesthesiologist ignorant of preoperative airway evaluation. Patients with Cormack and Lehane Class III and IV were regarded as difficult intubation. Sensitivity, specificity, and positive and negative predictive values of MMT and ULBT were computed. Agreement between two tests with the Cormack Lehane test was determined by the Kappa coefficient.ResultsIn our research, the occurrence of difficult intubation was found to be 10.2% (23 cases of difficult intubation out of 225 patients). In our analysis, we found the sensitivity (95.5% vs. 95.4%), specificity (54.8% vs 50.0%), positive predictive value (91.6% vs 93.1%), and negative predictive value (39.1% vs 39.1%) were almost comparable between modified Mallampati test and upper lip bite test. Kappa coefficient for the upper lip bite test (0.492) was slightly higher as compared to modified Mallampati scoring (0.454), but both the values are highly statistically significant (p-value <0.001).ConclusionBoth the upper lip bite test and modified Mallampati test are comparable with each other and since the upper lip bite test is easy to perform bedside test we recommend it to be used alone or in collaboration with other tests in assessing difficult airways.

The Ratio of Height to Thyromental Distance (RHTMD) and Height to Sternomental Distance (RHSMD) as the Predictive Tests for Difficult Tracheal Intubation.

Background: Pre-operative evaluation is a cornerstone in identifying patients with a risk of difficulty in intubation. Thyromental distance (TMD) is the most commonly used predictor of difficult intubation. However, it’s not a reliable indicator of difficulty during intubation because it differs with patients’ body & size proportion. The present study was done for the evaluation of the ratio of height to thyromental distance (RHTMD) and ratio of height to sternomental distance (RHSMD) as difficult airway predictors. Methods: Data was taken from 400 consecutive patients posted for the need for anesthesia with intubation during surgery. Preoperatively examination of RHTMD and RHSMD was done. Difficulty during intubation has been explained in this current study with Cormack and Lehane grade 3 or 4. The positive and negative predictive values, as well as sensitivity and specificity of individual tests, were calculated as per the recognized formula.Results: The study enrolled 400 patients, which include a maximum number of participants (138 [34.5%]) from the 41-50 year age group. On analyzing RHTMD and RHSMD, the former was found to have a better predictive value than RHSMD (p=0.001). RHTMD & RHSMD was found to have 62.5% & 37.50% sensitivity, respectively. RHTMD was found to have better specificity, positive & negative predictive values, and accuracy than RHSMD.Conclusion: RHTMD was observed to have superior precision in anticipating difficulty in intubation compared to RHSMD.

Significance of Ratio of the Neck Circumference and Thyromental Distance as a Predictor of Difficult Intubation in Obese Patients

Objective: To ascertain the diagnostic accuracy of raised neck circumference to thyromental distance ratio (NC/TMD) for difficulty in intubation among patients with obesity keeping grades III and IV of Cormack and Lehane's score as the gold standard.&#x0D; Study Design: Cross-sectional validation study.&#x0D; Place and Duration of Study: Anesthesiology Department, Combined Military Hospital Rawalpindi, from Jul to Dec 2017.&#x0D; Methodology: One hundred and thirty obese patients who had to undergo surgery under general anaesthesia were included in the study. All the patients underwent measurement of neck circumference to thyromental distance ratio, and raised neck circumference to thyromental distance ratio was noted. Difficult intubation was labelled according to the grades III and IV of Cormack and Lehane's score.&#x0D; Results: In this study, 130 cases were included. Fifty-eight patients were males, and 72 were females. Diagnostic accuracy of raised neck circumference to thyromental distance ratio for difficulty in intubation among patients who were obese, was recorded where sensitivity was 83.87%, and specificity was found to be 91.92%, positive predictive value as 76.47%, negative predictive value as 94.79%, the accuracy rate was calculated as 90%.&#x0D; Conclusion: Our study showed that difficulty in intubation is more frequent in patients who are obese and the neck circumference to thyromental distance ratio is a reliable method for foreseeing difficult intubation compared to other established predictors with cut off value of 5.0.

Mallampati Score Is an Independent Predictor of Active Oxygen Therapy in Patients with COVID-19.

Mallampati score has been identified and accepted worldwide as an independent predictor of difficult intubation and obstructive sleep apnea. We aimed to determine whether Mallampati score assessed on the first patient medical assessment allowed us to stratify the risk of worsening of conditions in patients hospitalized due to COVID-19. A total of 493 consecutive patients admitted between 13 November 2021 and 2 January 2022 to the temporary hospital in Pyrzowice were included in the analysis. The clinical data, chest CT scan, and major, clinically relevant laboratory parameters were assessed by patient-treating physicians, whereas the Mallampati score was assessed on admission by investigators blinded to further treatment. The primary endpoints were necessity of active oxygen therapy (AOT) during hospitalization and 60-day all-cause mortality. Of 493 patients included in the analysis, 69 (14.0%) were in Mallampati I, 57 (11.6%) were in Mallampati II, 78 (15.8%) were in Mallampati III, and 288 (58.9%) were in Mallampati IV. There were no differences in the baseline characteristics between the groups, except the prevalence of chronic kidney disease (p = 0.046). Patients with Mallampati IV were at the highest risk of AOT during the hospitalization (33.0%) and the highest risk of death due to any cause at 60 days (35.0%), which significantly differed from other scores (p = 0.005 and p = 0.03, respectively). Mallampati IV was identified as an independent predictor of need for AOT (OR 3.089, 95% confidence interval 1.65–5.77, p < 0.001) but not of all-cause mortality at 60 days. In conclusion, Mallampati IV was identified as an independent predictor of AOT during hospitalization. Mallampati score can serve as a prehospital tool allowing to identify patients at higher need for AOT.

Assessment of predictors for difficult intubation and laryngoscopy in adult elective surgical patients at Tikur Anbessa Specialized Hospital, Ethiopia: A cross-sectional study

BackgroundGeneral anesthesia is not without morbidity. One of the well-known life-threatening events associated with general anesthesia is difficult airway which can happen during induction of anesthesia while attempting to insert the endotracheal tube with the aid of a laryngoscope. Difficult intubation, inadequate ventilation, and esophageal intubation are the principal causes of death or brain damage related to airway manipulation. ObjectiveThe main objective of this study was to assess the magnitude and predictors for difficult laryngoscopy and intubation among surgical patients who underwent elective surgery under general anesthesia with endotracheal intubation at Tikur Anbessa Specialized Hospital from February 1 to March 30, 2019. Materials &methodAn institutional based cross sectional study was conducted from February 1 to March 30, 2019 on patients who underwent elective surgery under general anesthesia with endotracheal intubation. Data on socio-demographic characteristics, preanesthetic airway assessment and laryngoscopic view were collected. Data were analyzed by SPSS Version 20.0. Chi- square test, binary logistic regression and multivariate analysis were performed. Tables and texts were used to present data. A p value less than 0.05 was considered as statistically significant. ResultsThe magnitude of difficult laryngoscopy, difficult intubation, and failed intubation were 12.2%, 6.1%, and 0.67%, respectively. Upper Lip Bite Test (ULBT) had a higher sensitivity (90.2%) and negative predictive value of 85.3%. Mallampati had a sensitivity of 45.8% and negative predictive value of 86% in predicting difficult laryngoscopy. Mallampati grade, thyromental distance and ratio of height to thyromental distance (HRTMD) have also showed greater sensitivity (69.6%, 58.3% and 47.8%, respectively) when compared to other tests in predicting difficult intubation. Mallampati class, upper lip bite test (ULBT) and inter-incisor distance (IID) are independent predictors for difficult laryngoscopy (p < 0.05). Furthermore, Mallampati class, Thyromental distance and ratio of height to thyromental distance (HRTMD) are identified as independent predictors of difficult intubation (p < 0.001). Conclusionand recommendation: Mallampati class, Thyromental distance and Ratio of height to Thyromental distance (HRTMD) can predict the probability of difficult endotracheal intubation in adult patients. Whereas, Mallampati class and upper lip bite test (ULBT) predicts higher probability for difficult laryngoscopy.

Positive Predictive Value of Upper Lip Bite Test in Predicting Difficult Intubation

Objective: To determine the positive predictive value of upper lip bite test in predicting difficult intubation by taking Cormack and Lehane classification as gold standard. Design of the Study: Cross sectional study. Study Settings: This cross-sectional study was conducted at Department of Anesthesiology, Sir Ganga Ram Hospital, Lahore from 04/06/2021 to 03/12/2021. Materials and Methods: This study involved 313 patients of both genders, aged between 18-70 years undergoing general anesthesia on elective lists having positive upper lip bite test (Grade-III). On the basis of Cormack and Lehane Classification, the diagnosis was verified. Results of the ULBT were compared to the Cormack and Lehane grade-III and grade-IV diagnoses. Every patient's written informed permission was obtained. Results: In The mean age of the patients was 43.78±12.32 years. Majority (n=150, 47.9%) of the patients were aged between 36-52 years. There were 198 (63.3%) male and 115 (36.7%) female patients in the study group. Among the procedures, herniorrhaphy (32.9%) and cholecystectomy (26.8%) were the more frequent procedures followed by thyroidectomy (17.6%), tonsillectomy (13.1%) and mastectomy (9.6%). Majority (42.8%) of the patients belonged to ASA Class-I followed by ASA Class-II (29.7%) and ASA Class-III (27.5%). Difficult intubation was confirmed in 232 (74.1%) patients on Cormack and Lehane Classification (as per operational definition). Thus there were 232 true positive patients with 81 false positive patients. With the gold standard Cormack and Lehane Classification, the upper lip bite test yielded a positive predictive value of 74.1 percent in the prediction of difficult intubation. Conclusion: According to the gold standard of Cormack and Lehane Classification, an upper lip bite test (Grade-III) has a 74.1 percent positive predictive value for difficult intubation in patients undergoing general anaesthesia with endotracheal intubation on the elective list. Keywords: Difficult Intubation, Cormack and Lehane Classification, Upper Lip Bite Test

9: Evaluation of the neck circumference to thyromental distance ratio as a predictor of difficult intubation-A prospective observational study

Background and Aims:Preoperative identification of difficult airway and subsequent planning is of utmost importance for patient safety. Previous studies have identified neck circumference to thyromental distance ratio (NC/TMD) as a reliable predictor of difficult intubation in obese patients.[1] But, there is lack of a reported study evaluating NC/TMD in the non-obese patients. The aim of our study was to evaluate the NC/TMD as a predictor of difficult intubation in both obese and non-obese patients.Methods::A prospective observational study was conducted after obtaining Institutional Ethics Committee clearance and written informed consent from each patient. Hundred adult patients undergoing elective surgeries under general anaesthesia with orotracheal intubation were included in this study. Difficulty in intubation was assessed using Intubation Difficulty Scale (IDS>5).[2] The NC/TMD was calculated and was compared with other established parameters in predicting difficult intubation in both obese and non-obese patients. Statistical Package for the Social Sciences (SPSS) software (version 22.0) was used for statistical analysis.Results:Univariate logistic regression analysis showed that sex, weight, body mass index, inter-incisor gap, Mallampati classification, neck circumference, thyromental distance, sternomental distance and NC/TMD had a significant association with difficult intubation. NC/TMD has a higher sensitivity, specificity, PPV and NPV with a large area under curve (AUC) (P = 0.000) in comparison to other parameters.Conclusion:The NC/TMD is a reliable and better predictor of difficult intubation in both obese and non-obese patients in comparison to neck circumference, thyromental distance, sternomental distance alonePredictorGroupSensitivitySpecificityPPVNPVAUC P NC/TMDNon obese (>4.950)100.0087.2761.11100.000.9790.000Obese (>5.050)94.7473.3381.8291.670.9120.000BMITotal83.3372.8656.8291.070.870<0.001Neck circumferenceNon obese (>35.5 cm)90.9161.8232.2697.140.8290.001Obese (>35.5 cm)84.2160.0072.7375.000.7580.011Thyromental distanceNon obese (<7.250 cm)100.0069.0939.29100.000.9020.000Obese (<7.250cm)89.4773.3380.9584.620.8280.001Sternomental distanceNon obese (<14.5 cm)81.8280.0045.0095.650.7830.003Obese (<15.5cm)78.9526.6757.6950.000.5160.876

Abstract No.: ABS3247 : Ratio of Height To ThyroMental Distance(RHTMD): A new predictor for assessment of difficult intubation in non-obese.

Background & Aims:The recognition of difficult intubation during preoperative checkup is very important for the anaesthesiologist. Various anatomical parameters assist in predicting difficult intubation. Till date, there are no predictors available to precisely asses the risk of difficult intubation pre-operatively. Therefore, we aimed to identify the adequacy of predictors for pre-operative assessment of difficult intubation.Methods:After ethical approval, a total of 200 non-obese patients (body mass index ≤30) were recruited in this prospective observational study after obtaining informed consent. mouth opening (MO), modified Mallampati grade (MMG), neck circumference (NC), thyromental distance (TM), sternomental distance (SM), neck movements (NM) and Ratio of Height To ThyroMental Distance (RHTMD) were measured preoperatively. In each patient the validated intubation difficulty score (VIDS) was assessed intraoperatively by the anaesthetist. All patients were divided into two groups on the basis of easy (IDS Score <5) or difficult intubation (IDS Score ≥5). Multivariate logistic regression analysis including all variables was used to create a predictive model.Results:Laryngoscopy was difficult in 12% of the patients. The MO, MMG, NM, NC, TM, SM, NC/TM were significantly different between easy and difficult intubation. AUROC for the TM , SM , NC/TM , RHTMD and MMG were 0, 270, 0.138, 0.848 , 0.807 and 0.699, respectively. Among all indices, NC/TM and RHTMD were found to have a high sensitivity and specificity. NC/TM had the maximum AUROC followed by RHTMD.Conclusion:Among non-obese patients, NC/TMD ratio and RHTMD are better predictors of difficult intubation pre-operatively.

Abstract No. : ABS1378: Correlation between upper airway ultrasound and Cormack- Lehane grading during laryngoscopy-A prospective study

Background & Aims:Difficult and failed tracheal intubation after direct laryngoscopy is a dreaded complication of general anaesthesia. Preoperative prediction of the Cormack-Lehane (CL) grade with ultrasonographic measurements of ANS-Hyoid, ANS-VC, PES&EVL can help in better airway management during general anaesthesia.Methods:We studied 100 patients undergoing elective surgery under general anaesthesia. Study was carried out in two phases. Firstly, during preanaesthetic checkup, Mallam pati grade (MPG), Sternomental distance (SMD), Thyromental distance (TMD) and ultrasound measurements of the anterior neck soft tissue thickness at the level of the hyoid (ANS-Hyoid), at the level of the vocal cords (ANS-VC) and ratio of the depth of the pre-epiglottic space (Pre-E) to the distance from the epiglottis to the mid-point between the vocal cords (E-VC) were obtained, CL grade was noted during laryngoscopy. Chi-square test wasapplied to predict any statistically correlation between measurement of ultrasonographic parameters and CL grade.Results:The incidence of difficult intubation was 15%. An ANS-VC>0.32 had sensitivity of 100% in predicting a CL grade of 3 and4, which was higher than ANS-hyoid, PES/EVL, MPG, SMD, TMD, while specificity and PPV were lower. Conclusion:Ultrasound is a useful test in airway assessment. ANS-VC>0.32 is a potential predictor of difficult intubation. ANS-hyoid, PES/EVL are not indicative of difficult intubation.

Predisposing Factors of Difficult Tracheal Intubation Among Adult Patients in Aliabad Teaching Hospital in Kabul, Afghanistan - A Prospective Observational Study.

BackgroundAirway management may be a considerable challenge for anesthesiologists. Currently used preoperative screening tests are known to lack sufficient specificity and sensitivity. Nevertheless, preoperative screenings and the combination of various tests are highly recommended to reduce the risk of unexpected difficult or failed airway management.PurposeThis study aims to determine if socio-demographic characteristics can predict difficult intubation among adult patients scheduled for elective surgeries under general anesthesia in Aliabad Teaching Hospital, Kabul, Afghanistan.MethodsA total of 341 patients were selected based on consecutive sampling method. Informed consent forms were obtained before inclusion in the study. Data were collected using a data collection form. Age, gender, ASA physical status and ethnicity were recorded for each participant. Airway assessment tests such as mouth opening (MO), thyromental distance (TMD), and Mallampati classes, inability to prognath (AP) and neck mobility and size (NM) category were conducted by research team. Data were initially entered into an Excel data sheet and then exported to SPSS Statistics version 22 for analysis.ResultsFrom 28 October 2018 to 30 January 2019, a total of 341 patients included in the study. Of these, 193 (56.6%) were male and 148 (43.4%) were female. The mean age of the subjects was 36.98 ± 15.048 years. More than half (54.5%) of the study population were Tajiks. Patients from the Hazara ethnicity, female patients, older patients and those suffering from systemic diseases found to be more difficult to intubate. We recognized that, Mallampati classes ≥3, small MO, short TMD, AP, reduced NM were also associated with difficult intubation. Multiple logistic regression analysis of the associated factors determined that increased age more than 40 years, AP and small MO were independent predictors of difficult intubation.ConclusionThe study findings show that Hazara ethnicity, female patients, increasing age and systemic disease have significant associations with difficult intubation. Mallampati classes III and IV, MO ≤4 cm, TMD ≤6 cm, and reduced NM had higher risks of difficult intubation. Multiple logistic regression analysis determined that increased age, AP and MO were independent predictors for difficult intubation.

The assessment of risk factors associated with difficult intubation as endocrine, musculoskeletal diseases and intraoral cavity mass: A nested case control study.

The predictive factors of difficult airway have been studied to reduce especially the incidence of unanticipating difficult intubation, provide patient safety, and avoid wasting resources. In this study, it was aimed to investigate whether endocrine, musculoskeletal diseases, presence of intraoral mass, and demographic factors have predictive values in the evaluation of difficult air-way as well as frequently used airway assessment tests. This study was designed a nested-case control study. After eligibility criterions, totally 1012 patient data were collected, 92 of them were difficult intubation, 920 of them were non-difficult intubation patients (1: 10 ratio). Demographic characteristics of the patients (age, gender), body mass index (BMI), Mallampati, Cormack-Lehane Score (CLS), sternomental distance (SMD), inter incisor gap (IIG), type of surgery, endocrine, musculoskeletal and cardio-pulmonary diseases, and the presence of intraoral mass were compared between groups. Age >52 years, male gender, ASA 3-4, higher BMI, CLS 3-4, Mallampati 3-4, IIG <4 cm, and SMD <10 cm were found statistically significant in terms of difficult intubation. Besides, a statistically significant relationship was found when the groups were compared in the presence of intraoral mass (17.57 times higher, p<0.05), endocrine diseases (3.51 times more common, p<0.05) and musculoskeletal system diseases (4.5 times higher, p<0.05). In this study, it was demonstrated that endocrine disorders such as diabetes mellitus and thyroid disorders, musculoskeletal system diseases, and the presence of intraoral cavity mass should be used as predictors for difficult intubation with commonly used airway assessment tests.

Comparative Evaluation of Difficult Intubation Predictors in Children Under Two Years of Ages.

BackgroundTracheal intubation is the most reliable way of securing an airway. Pediatric airway management is one of the significant challenges, especially for non-pediatric anesthesiologists. Early airway evaluation for detecting difficult intubation and preventing catastrophic events is necessary before anesthesia, especially in children. ObjectivesTherefore, this study was done to compare some valuable adult predictors in children under two years of age.MethodsThis prospective descriptive-analytical study was performed on 405 children under two years of age that were referred for elective surgery under general anesthesia with endotracheal intubation in Imam Hossein Hospital, Isfahan. Under sedation in a supine position, we measured items, including age, weight, height, stern omental distance (SMD), mouth opening (MO), neck circumference (NC), acromio-axillo-suprasternal notch index (AASI), and intubation difficulty scale score (IDS). An expert anesthesiologist did laryngoscopy and intubation, and difficult cases were recorded.ResultsOur study showed that the frequency of difficult intubation with IDS > 4 was %16, and with IDS > 5 was %3. The variables, including age, weight, height, and SMD, significantly predicted difficult intubation. The cut-off points for age < 6 months, weight < 5/9 kg, height < 61 cm, and SMD < 5/3 cm were obtained, respectively. Other variables, such as MO, AASI, NC, and sex, were unreliable predictors for difficult intubation.ConclusionsWe found that IDS > 4, age< 6-month, weight < 5/9 kg, and SMD < 5/3 cm are predictors for difficult intubation. It is helpful for the anesthesiologist to measure these predictions before anesthesia is started to find who has difficult intubation.