Comparison of Upper Lip Bite Test with Modified Mallampati Score in Predicting Difficult Intubation

Background and Aims: Identifying a patient with a difficult airway is important in planning anaesthetic management so that endotracheal intubation can be achieved safely. This study aims to compare modified Mallampati score with Upper Lip Bite Test to predict difficult intubation using intubation difficulty scale. Materials and methods: A prospective study was carried on 104 patients, both sexes aged between 18 to 60 years scheduled for elective surgeries under general anaesthesia fulfilling inclusion and exclusion criteria. Patient airway was evaluated by MMT and ULBT preoperatively. Predictors of difficult endotracheal intubation were assigned to MMT class III and IV, ULBT class III. After premedication and induction laryngoscopy was performed. After successful intubation Intubation difficulty score was noted down based on the sum of seven assessing parameters. A score >5 was considered difficult intubation. Results: The incidence of difficult intubation in the study was 10.6% (i.e. 11 out of 104 patients). In this study ULBT had a higher sensitivity (90.9% v/s 18.20%), specificity (95.7% v/s 75.3%) PPV (71.4% v/s 8%) and NPV (98.9% v/s 88.6%) than that of MMT Conclusion: Upper lip bite test is better at predicting difficult intubation with higher accuracy when compared to Modified Mallampati test. Both the tests are good predictors of easy intubation. Keywords: Upper Lip Bite Test (ULBT), Modified Mallampati test (MMT), Intubation Difficulty scale (IDS), airway assessment. Difficult intubation prediction, Difficult airway

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

Background: Tracheal 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. Objectives: Therefore, this study was done to compare some valuable adult predictors in children under two years of age. Methods: This 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. Results: Our 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. Conclusions: We 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.

Difficult Airway Prediction Score for Intubation in Emergency Departments: A Retrospective Cohort Study

Objective: Difficult intubation is associated with an increasing number of endotracheal intubation attempts. Repeated endotracheal intubation attempts are in turn associated with an increased risk of adverse events. Clinical prediction tools to predict difficult airway have limited application in emergency airway situations. This study was performed to develop a new model for predicting difficult intubation in the emergency department.Methods: This retrospective study was conducted using an exploratory model at the Emergency Medicine of Ramathibodi Hospital, a university-affiliated super-tertiary care hospital in Bangkok, Thailand. The study was conducted from June 2018 to July 2020. The inclusion criteria were an age of ≥15 years and treatment by emergency intubation in the emergency department. Difficult intubation was defined as a Cormack–Lehane grade III or IV laryngoscopic view. The predictive model and prediction score for detecting difficult intubation were developed by multivariable regression analysis.Results: During the study period, 617 patients met the inclusion criteria; of these, 83 (13.45%) had difficult intubation. Five independent factors were predictive of difficult intubation. The difficult airway assessment score that we developed to predict difficult airway intubation had an accuracy of 89%. A score of >4 increased the likelihood ratio of difficult intubation by 7.62 times.Conclusion: A difficult airway assessment score of >4 was associated with difficult intubation.

Upper lip bite test compared to modified Mallampati test in predicting difficult airway in obstetrics: A prospective observational study

Difficult airway and intubation can have dangerous sequela for patients if not managed promptly. This issue is even more challenging among obstetric patients. Several studies have aimed to determine whether the test to predict a difficult airway or difficult intubation, is higher in accuracy. This study aims to compare the upper lip bite test with the modified Mallampati test in predicting difficult airway among obstetric patients. During this prospective observational study, 184 adult pregnant women, with ASA physical status of II, were enrolled. Difficult intubations of Cormack-Lehane grade III and IV were defined as difficult airways and difficult intubation in this study. Upper lip bite test, modified Mallampati test, thyromental distance and sternomental distance were noted for all patients. Modified Mallampati test, upper lip bite test and sternomental distance had highest specificity. Based on regression analysis, body mass index and Cormack-Lehane grade have a significant association. Modified Mallampati test was the most accurate test for predicting difficult airway. The best cut-off points of thyromental distance and sternomental distance in our study were 5cm and 15cm, respectively, by receiver operating characteristic curve analysis. Based on the results of the present study, it can be concluded that in the obstetric population, modified Mallampati test is practically the best test for predicting difficult airway. However, combining this test with upper lip bite test, thyromental distance and sternomental distance might result in better diagnostic accuracy.

Thyromental Height - As a Predictor of Difficult Laryngoscopy

The fundamental responsibility of the anaesthesiologist and one of the most important steps in anaesthesia practice is the intubation and maintenance of the airway. The integral part of pre-anaesthetic evaluation to recognize a potentially difficult airway is the airway assessment. There are multitude of bedside screening tests which are helpful to predict a difficult airway but the accuracy is doubtful. Thus, pointing out a single reliable predictor of difficult intubation is important. Accordingly, this study aims to evaluate the practicality of thyromental height test alone as a sole predictor of difficult laryngoscopy in our present population. Ethical clearance was obtained and after taking an informed consent, a randomised prospective observational study was conducted on 315 adult patients who were posted for elective surgical procedures under general anaesthesia with endotracheal intubation. On the day before the surgery, airway was assessed and Thyromental height (TMHT) was measured. Laryngoscopy was performed intra-operatively and Cormack Lehane’s grading was noted. The evaluation of the accuracy of thyromental height in predicting difficult laryngoscopy was done by comparing the preoperative assessment data and laryngoscopy findings. In our study, the mean thyromental height observed was 5.4cm. Thyromental height at cut off of 50mm had a high negative predictive value of 94.1% and high sensitivity of 72.5%, but with low specificity of 64.2% (P value 0.000). When the cut off was emended to 48mm, sensitivity of the test decreased to 56.2% and specificity increased to 79.8% (P value 0.002).The conducted study demonstrates the usefulness of thyromental height. It substantiates the good sensitivity of thyromental height for predicting difficult intubation. But, the validation will require further studies in more diverse patient population.

Airway assessment and management

This chapter provides detailed, practical and up-to-date information on management of the airway. It demystifies airway terminology, outlines airway assessment, and describes the management of the unanticipated difficult airway in adults. It includes a new section on intubating critically ill patients using the vortex approach, and outlines the equipment and techniques used to aid airway management. It gives practical information on the emergency front of neck airway and strategies to approach the obstructed airway. It explains rapid sequence induction, inhalational induction, awake tracheal intubation, and extubation after difficult intubation. It contains new sections on apnoeic oxygenation and how to manage patients with airborne respiratory viruses.