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Background and objectives Several anthropometric measurements have been suggested to identify a potentially difficult airway. We studied thyromental height (TMH) as a predictor of difficult laryngoscopy and difficult intubation. We also compared TMH, ratio of height to thyromental distance (RHTMD), and thyromental distance (TMD) as predictors of difficult airway. Methods This cross-sectional observational study was conducted in 300 adult surgical patients requiring tracheal intubation. Preoperatively airway characteristics were assessed. Standard anesthesia was administered. Degree of difficulty with mask ventilation, laryngoscopic view, duration of laryngoscopy, and difficulty in tracheal intubation (intubation difficulty scale score) were noted. Multivariate logistics regression analysis was performed to identify independent predictors for difficult laryngoscopy. Results Laryngoscopy was difficult in 46 of 300 (15.3%) patients; all 46 patients had Cormack-Lehane grade 3 view. Duration of laryngoscopy was 27 ± 11 s in patients with difficult laryngoscopy and 12.7 ± 3.9 s in easy laryngoscopy; p = 0.001. Multivariate analysis identified that TMH, presence of short neck, and history of snoring were independently associated with difficult laryngoscopy. Incidence of difficult intubation was 17.0%. A shorter TMH was associated with higher IDS scores; r = -0.16, p = 0.001. TMH and duration of laryngoscopy were found to be negatively correlated; a shorter TMH was associated with a longer duration of laryngoscopy; r = -0.13, p = 0.03. The cut-off threshold value for TMH in our study is 4.4 cm with a sensitivity of 66% and a specificity of 54%. Conclusion Thyromental height predicts difficult laryngoscopy and difficult intubation. TMD and RHTMD did not prove to be useful as predictors of difficult airway.

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

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.

Introduction and Aims: Difficult laryngoscopy [poor visualisation of larynx] is a surrogate indicator of difficult intubation and inability to manage difficult visualisation of larynx (DVL) can be life threatening. This study is performed to assess the ability of new index –Acromio -Axillo-Suprasternal Notch Index to predict difficult laryngoscopy in patient undergoing general anaesthesia in addition to other common predictors. Material and Methods: 100 patients with ASA class I and II candidate for general anaesthesia with endotracheal intubation were enrolled to this study. The four usual tests Modified MallampatiTest[MMT], Ratio Of Height to Thyromental Distance[RHTMD], Neck Circumference/ Thyromental distance, Sternomental distance difference were assessed before induction of anaesthesia. The new test AASI is calculated as follow: 1) Using a ruler a line is drawn vertically from the top of the acromion process to the superior border of the axilla at the pectoralismajor muscle named as line A. 2) A second line is drawn perpendicular to line A from the suprasternal notch (line B) and 3)That portion of line A that lies above where line B bisects line A is line C. AASI is calculated from the length of line C divided by line A[AASI = C/A]. By a skilled anaesthesiologist with more than 5 years of experience & who was unaware of the study, A laryngoscopy was done and based on Cormack-Lehane classification, grading of laryngoscopy was recorded. Sensitivity, specificity, positive predictive value and negative predictive value with 95% Confidence Interval for each airway predictor in isolation was studied. Results: DVL observed in 12% patients. We observed that sensitivity,specificity,PPV,NPV,AUC of Roc[95% confidence interval] of AASI was 80%[44.4-97.5%], 95.56%[89-98.8%],66.67%[42.22-84.6%],97.7%[92.6-99.33%},0.985[0.898-0.988]respectively & these results are better than other conventional methods of difficult airway predictors. Conclusion: AASI more than or equal to 0.5 is a good predictor of difficult visualisation of larynx (DVL) at direct laryngoscopy.

The goal of this study was to determine the utility of submental ultrasound parameters in distinguishing difficult airway management from easy airway management. Forty-one adult patients who underwent elective surgery under general anesthesia with endotracheal intubation from March to December 2018 were included. We used submental ultrasound to measure tongue base thickness (TBT) in the midsagittal plane and the distance between lingual arteries (DLA) in the transverse dimension. The primary outcome was difficult laryngoscopy, and the secondary outcome was difficult mask ventilation. Receiver operating characteristic curve analysis and logistic regression revealed no correlation between difficult laryngoscopy and SMUS measurements. Nevertheless, patients with difficult mask ventilation had significantly higher TBT (p = 0.009) and longer DLA (p = 0.010). After adjustment of confounding factors, increased TBT (>69.6 mm) was the sole independent predictor of difficult mask ventilation. The results indicated that SMUS is effective in predicting difficult mask ventilation but not difficult laryngoscopy.

Objectives: We conducted this study to compare the accuracy of three diagnostic tests; ratio of height to thyromental distance (RHTMD), Modified Mallampati Test (MMT) and Upper Lip Bite Test (ULBT) in predicting difficult laryngoscopy using Cormack and Lehane grade as gold standard.Methods: This study was conducted in Aga Khan University Hospital, Karachi. Based on calculated sample size, 383 patients who required endotracheal intubation for elective surgical procedures were enrolled with consecutive sampling techniques during August 2014 to August 2015 for this cross-sectional study. Primary investigator used RHTMD, ULBT, and MMT for assessing the airway and correlated with laryngoscopic view.Results: A total of 383 patients were incorporated in this research, out of which 59(15.4%) classified as difficult laryngoscopy based on Cormack and Lehane (CL) grading. Sensitivity, specificity, positive predictive value, negative predictive value and accuracy of RHTMD (84.7%, 90.1%, 60.9%, 97%, 89.3%) and ULBT (83.1%, 89.2%, 58.3%, 96.7%, 88.3%) values were highest as compared to MMT (30.5%, 84.3%, 26.1%, 86.9%, 79.9%). The area under a receiver-operating characteristic curve (AUC of ROC curve) for ULBT and RHTMD was significantly more than for MMT (P

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

Background: Thyromental Height Test is a relatively new, easy method considered as a more accurate predictor of difficult laryngoscopy than existing methods. The aim of this study was to evaluate its accuracy in predicting difficult laryngoscopy as compared to commonly used methods.Methods: This hospital based, cross-sectional, observational study was conducted on 246 patients scheduled for surgery under general anesthesia with endotracheal intubation. Airway assessment was done during pre-anesthetic assessment by Thyromental Height Test, Modified Mallampati Test, Thyromental Distance and Sternomental Distance measurements and predicted as ‘difficult’ or ‘easy’ laryngoscopy based on accepted cut-off values. Direct laryngoscopic view was assessed after administration of general anesthesia by a laryngoscopist unaware of the pre-anesthetic assessments and recorded as ‘actual’ difficult or easy laryngoscopy based on Cormack-Lehane grades. The sensitivity, specificity, positive predictive value, negative predictive value and accuracy of each clinical test were determined. Results: Thyromental Height Test had the highest sensitivity (71.42%) and negative predictive value (98.9% respectively) but lowest accuracy (77.2%). Maximum specificity was observed with Thyromental Distance and Sternomental Distance (97.49% each). Thyromental Distance had the highest positive predictive value (25%) and accuracy (95.52%). Conclusions: Thyromental Height Test, with its high sensitivity, is a useful predictor of difficult laryngoscopy. However, due a high number of false positives and relatively low accuracy, it cannot be considered as a sole, reliable and accurate predictor of difficult laryngoscopy. Keywords: Accuracy; difficult laryngoscopy; predictor; thyromental height

BACKGROUND Unanticipated difficult airway can lead to serious morbidity and mortality in Head and Neck cancer surgical patients. We wanted to determine the incidence of difficult laryngoscopy, difficult intubation and their correlation with routine bedside predictors of difficult airway. METHODS In this prospective observational study, 30 patients posted for elective oral and neck cancer surgery were assessed preoperatively and history of addiction, previous head and neck chemoradiation therapy, Mallampati grade, inter-incisor distance, thyromental distance and neck movements were noted. After standard anaesthetic induction, Cormack Lehane Grade was noted on first direct laryngoscopy attempt and intubation difficulty was assessed using intubation difficulty scale on the basis of seven variables. RESULTS Tobacco chewing was found to be a major risk factor for developing H & N cancer in 90% of subjects. Incidence of difficult laryngoscopy was 46.66% and incidence of difficult intubation was 20% in our study. On doing univariate logistic regression analysis, Cormack Lehane grade >=3 was found to have significant correlation with difficult intubation but on assessing independent correlation using multivariate regression analysis, none of the predictors had any significant correlation with difficult intubation. CONCLUSIONS The routine bedside predictors of difficult airway are not accurate indicators of difficult intubation in Head & Neck cancer surgical patients.

The problem of difficult airways remains relevant for many years. Complications associated with unpredictable difficult airways often lead to the lethal outcome or neurological problems. This article analyzes the causes of difficult airways in patients with burns of face and neck. Such patients face a higher risk to develop difficult airways and it is impossible to follow the traditional procedure for maintaining airway patency. The article expresses the opinion about the inability of modern methods for assessing airway patency to predict possible problems associated with tracheal intubation and ventilation of patients with burns of face and neck.

Background: The screening tests used for pre-operative evaluation of airway to predict difficult laryngoscopy and intubation have variable diagnostic accuracy. The unanticipated poor laryngeal view is gold standard for defining difficult intubation. We aimed to find out the prevalence of difficult laryngoscopy and intubation, which airway parameter better predicts difficult intubation and whether difficult laryngoscopy is associated with difficult intubation or not.Methods: This analytic cross sectional study was conducted in 665 ASA I/II adult patients, aged 18-65, without obvious airway pathology undergoing elective surgery under general anesthesia. The pre-operative screening tests included mouth opening, modified mallampatti, ratio of height to thyromental distance, sternomentaldistance and upper lip bite test. Cormack-Lehane grade III/ IV was defined as difficult laryngoscopy and potentially difficult intubation. Sensitivity, specificity, positive predictive value, negative predictive value, accuracy and area under curve at 95% confidence interval was calculated for all five screening tests. Results: The prevalence of difficult laryngoscopy and intubation was 6.6% (44 cases). The upper lip bite test because of its highest specificity, positive predictive value, negative predictive value, accuracy and area under curve (99.7%; 93.9%; 99.7%; 95.2%; 85.1% respectively) with moderate level of sensitivity (70.5%) was better predictor of difficult intubation than other tests. The difficult laryngoscopy was associated with difficult intubation (p=0.00).Conclusions: The prevalence of difficult laryngoscopy and intubation was 6.6%.The upper lip bite test was a better predictor of difficult intubation and there was a significant association of difficult laryngoscopy with difficult intubation.Keywords: Difficult laryngoscopy and intubation; screening tests; upper lip bite test.

The poor reliability of traditional screening tools to identify a potentially difficult airway makes the difficult laryngoscopy and tracheal intubation rate remains at 1.5–13%.The hypothesis is tha...

BackgroundIn morbidly obese patients, airway management is challenging since the incidence of difficult intubation is 3 times that in normal patient. Standard preoperative airway evaluation may help to indicate for probability of difficult laryngoscopy. Recent studies have used ultrasonography-measured distance from skin to epiglottis and pretracheal soft tissue at the level of vocal cords, and cut-points of 27.5 mm and 28 mm respectively, to predict difficult laryngoscopy. The purpose of this study is to use ultrasonography-measured distance from skin to epiglottis for predicting difficult laryngoscopy in morbidly obese Thai patients.MethodsThis prospective observational study was approved by the Ethics Committee of the Faculty of Medicine, Prince of Songkla University. Data were collected from January 2018 to August 2020. Eighty-eight morbidly obese patients (BMI ≥ 35 kg/m2) requiring general anesthesia with endotracheal intubation for elective surgery in Songklanagarind Hospital were enrolled. Preoperatively, anesthesiologists or nurse anesthetists who were not involved with intubating the patients evaluated and recorded measurements (body mass index, neck circumference, inter incisor gap, sternomental distance, thyromental distance, modified Mallampati scoring, upper lip bite test, and distance from skin to epiglottis by ultrasound. The laryngoscopic view was graded on the Cormack and Lehane scale. ResultsMean BMI of the eighty-eight patients was 45.3 ± 7.6 kg/m2. The incidence of difficult laryngoscopy was 14.8%. Univariate analysis for difficult laryngoscopy indicated differences in thyromental distance, sternomental distance and the distance from skin to epiglottis by ultrasonography. The median (IQR) of thyromental distance in difficult laryngoscopy was 6.5 (6.3, 8.0) cm compared with 7.5(7.0, 8.0) cm in easy laryngoscopy (p-value 0.03). The median (IQR) of sternomental distance in difficult laryngoscopy was 16.8 (15.2, 18.0) cm compared with 16.0 (14.5, 16.0) cm in easy laryngoscopy (p-value 0.05). The mean distance from skin to epiglottis was 12.2 ± 3.3 mm Mean of distance from skin to epiglottis in difficult laryngoscopy was 12.5 ± 3.3 mm compared with 10.6 ± 2.9 mm in easy laryngoscopy (p-value 0.05). Multivariate logistic regression indicated the following factors associated with difficult laryngoscopy: age more than 43 years (A), thyromental distance more than 68 mm(B) and the distance from skin to epiglottis more than 13 mm(C). The scores to predict difficult laryngoscopy was calculated as 8A+7B+6C. One point is given for A if age was more than 43 years old, 1 point is given for B if thyromental distance was less than 6.8 cm and 1 point is given for C if the distance from skin to epiglottis by ultrasonography was more than 13.0 cm. The maximum predicting score is 21, which indicates a probability of difficult laryngoscopy among our patients of 36.36%, odds 0.57, likelihood ratio 3.29 and area under the ROC curve of 0.78.ConclusionsAge, thyromental distance and ultrasonography for the distance from skin and epiglottis can predict difficult laryngoscopy among obese Thai patients. The predictive score indicates the probability of difficult laryngoscopy.

The airway begins functionally at the nares. The septum divides the nasal cavity into two narrow cavities. The nasal cavity extends from the external nares to the posterior choanae, where it becomes continuous with the nasopharynx. Vertically it extends from the palate to the cribriform plate. Each half has a floor, roof, a lateral wall and a medial septum wall. The lateral wall is uneven because of the three bony projection known as conchae. 300 consecutive (apparently normal) American Society of Anaesthesiologist grade 1 &2 adult patients undergoing elective surgical procedures under general anaesthesia with endotracheal intubation at Medical college and teaching Hospital were the subjects in this study. Thyromental distance

Various clinical techniques have been used to assess difficult laryngoscopy, some of which are not sensitive or specific to predict difficult intubation. Hence unidentified difficult intubation can be challenging to the anesthesiologist. All patients were premedicated with Tab. Pantoprazole 40 mg given orally night before surgery. On the morning of surgery patient were shifted to the O.T, Non- Invasive Blood pressure, ECG, Spo2 monitors were connected and basal vitals were recorded. Patients were given Inj Fentanyl 2µg/kg, Inj Midazolam 25 µg/kg given IV and pre oxygenated for 3 mins. Mallampatti grade 3&4 were considered as predictors of difficult intubation. There were 29 cases out of 300 patients (9.7%) belong to Mallampatti Grade 3 & 4.

Introduction: Prediction of potentially difficult airway management during pre-operative period is determined by anatomy of oropharynx & range of movement of neck, clinically evaluated by various tests like Modified Mallampati Test, Upper Lip BiteTest, Thyromental Distance, ratio of Height to thyromental distance etc. We performed a study to compare significant direct relationship between MMT, ULBT, TMD, RHTMD & Cormack-Lehane (C-L) scale. Aims and Objective: 1) To elucidate the role of MMT, ULBT, TMD and RHTMD as simple bedside airway predictive tests & to study their direct correlation with difficult laryngoscopic view, using C-L grading. 2) To compare their ability to predict difficult laryngoscopy in various combinations. Materials and Methods: Type of study - prospective, observational & single blind. Sample Size: 450, 20-60 years, male/female, ASA I/II. Pre-operatively anaesthesiologist not involved in intubation evaluated & assessed ULBT, MMT & TMD in sitting position. Patient induced & laryngoscopy performed with Macintosh blade No.3 in sniffing position & laryngoscopic view determined by C-L grading. Result: On comparing CL-grading with other tests such as MMT, ULBT, TMD & RH MD in assessing difficult intubation, it was observed that there was statistically significant association with p Conclusion: We conclude that no single airway predictor test is sufficient for predicting difficult intubation. So, a combination of two or more airway predictor tests may predict difficult airway better. Keywords: Difficult intubation, Mallampati test, Upper lip bite test, Thyromental distance, RHTMD.

In patients with predictive features associated with easy direct laryngoscopy, videolaryngoscoy with the GlideScope has been shown to require less force when compared with Macintosh direct laryngoscopy.The aim of this study was to compare forces applied with Glidescope vs. Macintosh laryngoscopes in patients with predictive features associated with difficult direct laryngoscopy.A randomised study.Toronto General Hospital, a university tertiary centre in Canada.Forty-four patients aged over 18 years, with one or more features of difficult intubation, undergoing elective surgery requiring single-lumen tracheal intubation.We measured the force applied to oropharyngeal tissues by attaching three FlexiForce Sensors (A201-25) to the concave surface of Macintosh and GlideScope laryngoscope blades.Anaesthetists or experienced anaesthesia residents performed laryngoscopies with both devices in a randomised sequence.The primary outcome was peak force. The secondary outcomes were average force and impulse force. The latter is the integral of the force over the time during which the force acted.Complete data were available for 40 individuals. Peak and average forces decreased with GlideScope (17 vs. 21 N, P = 0.03, and 6 vs. 11 N, P 0.001, respectively). Laryngoscopy time increased with the GlideScope (30 vs. 18 s, P 0.001), resulting in similar median impulse forces (206 vs. 175 N, P = 0.92).GlideScope laryngoscopy resulted in reduced peak and average forces, but as the laryngoscopy duration increased, the product of force and time (impulse force) was similar with both devices.Clinicaltrials.gov Identifier: NCT01814176.

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.

Background Increased tongue volume measured by ultrasound has been proven to be related to difficult airways. Tongue volume is an indirect parameter and is derived from multiplying the midsagittal tongue cross-sectional area (CSA) by the tongue width. However, few studies have focused on the ability of tongue CSA and tongue width to predict difficult airways. This study aimed to investigate the predictive value of tongue CSA and tongue width for predicting difficult laryngoscopy and difficult intubation. Methods This study included 244 adult patients who underwent general anesthesia and endotracheal intubation. Demographic variables were collected, and clinical airway assessments were performed. A curvilinear low-frequency probe was used for ultrasonography, and midsagittal tongue CSA and tongue width were measured before anesthesia. The laryngoscopic view and the difficulty of intubation was graded or scored after induction of anesthesia. Results A total of 230 patients were analyzed. Twenty-eight (12.2%) patients experienced difficult laryngoscopy and twelve (5.2%) patients experienced difficult intubation. Midsagittal tongue CSA evaluated by ultrasonography could help identify patients with difficult laryngoscopy (sensitivity 0.71, specificity 0.60) and patients with difficult intubation (sensitivity 0.50, specificity 0.97). And tongue width could help identify patients with difficult laryngoscopy (sensitivity 0.39, specificity 0.89). Conclusions Ultrasonic measurement of midsagittal tongue CSA may be a valuable predictor of difficult laryngoscopy and difficult intubation. By contrast, tongue width measured by ultrasound may be a weak predictor of difficult laryngoscopy, but its predictive ability was questionable.

Airway issues in the pediatric age group contribute to significant morbidity and mortality under anesthesia. Neonates and infants are the most susceptible age group. Oxygen utilization in this age group is substantially higher, and this imparts poor tolerance to apnea, implying that pediatric patients can develop significant hypoxemia very rapidly, with ensuing profound bradycardia. While true difficult laryngoscopy is rare (1.3%), airway management in many pediatric patients presenting for neurosurgical procedures has certain unique considerations, including the fact that unlike adults, they cannot be intubated awake, and may often have to be induced without intravenous access.

BackgroundRoutine preoperative methods to assess airway such as the interincisor distance (IID), Mallampati classification, and upper lip bite test (ULBT) have a certain risk of upper respiratory tract exposure and virus spread. Condyle-tragus maximal distance(C-TMD) can be used to assess the airway, and does not require the patient to expose the upper respiratory tract, but its value in predicting difficult laryngoscopy compared to other indicators (Mallampati classification, IID, and ULBT) remains unknown. The purpose of this study was to observe the value of C-TMD to predict difficult laryngoscopy and the influence on intubation time and intubation attempts, and provide a new idea for preoperative airway assessment during epidemic.MethodsAdult patients undergoing general anesthesia and tracheal intubation were enrolled. IID, Mallampati classification, ULBT, and C-TMD of each patient were evaluated before the initiation of anesthesia. The primary outcome was intubation time. The secondary outcomes were difficult laryngoscopy defined as the Cormack-Lehane Level > grade 2 and the number of intubation attempts.ResultsThree hundred four patients were successfully enrolled and completed the study, 39 patients were identified as difficult laryngoscopy. The intubation time was shorter with the C-TMD>1 finger group 46.8 ± 7.3 s, compared with the C-TMDp1 finger group 98.9% than in the C-TMDPPPConclusionCompared with the IID, Mallampati classification and ULBT, C-TMD has higher value in predicting difficult laryngoscopy and does not require the exposure of upper respiratory tract.Trial registrationThe study was registered on October 21, 2019 in the Chinese Clinical Trial Registry (ChiCTR1900026775).

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

Background: The current global situation of COVID-19 epidemic is serious. Routine preoperative methods to assess airway such as the interincisor distance(IID), Mallampati classification, and the upper lip bite test(ULBT) have a certain risk of upper respiratory tract exposure and virus spread. The condyle-tragus maximal distance(C-TMD) can be used to assess the airway, and the assessment method does not require the patient to expose the upper respiratory tract, but its value in predicting difficult laryngoscopy compared to other indicators (Mallampati classification, IID, and ULBT) remains unknown. The purpose of this study was to observe the value of C-TMD to predict difficult laryngoscopy and the influence on intubation time and intubation attempts, and provide a new idea for preoperative airway assessment during epidemic.Methods: We enrolled adult patients who underwent general anesthesia and tracheal intubation. The IID, Mallampati test result, ULBT result, and the C-TMD of each patient were evaluated prior to the initiation of anesthesia. The primary outcome were difficult laryngoscopy defined as the Cormack-Lehane Level > grade 2 , the number of intubation attempts and intubation time.Results: A total of 304 patients were successfully included in the study, 39 patients were identified as difficult laryngoscopy. The intubation time was shorter with the C-TMD ＞1 finger group 46.8±7.3s, compared with the C-TMD ＜1 finger group 50.8±8.6s (p＜0.01).First attempt success rate was higher in the C-TMD ＞1 finger group than in the C-TMD ＜1 finger group (P＜0.01).The correlation between the C-TMD and Cormack-Lehane Level was 0.317(Spearman correlation coefficient, P＜0.001), and the area under the ROC curve was 0.699(P＜0.01). The C-TMD Conclusion: Compared with the IID , Mallampati classification and ULBT, the C-TMD has higher value in predicting difficult laryngoscopy, which can become a more favorable airway assessment method during the epidemic of COVID-19.Trial registration: The study was registered on October 21, 2019 in the Chinese Clinical Trial Registry (ChiCTR1900026775).

Background: The current global situation of COVID-19 epidemic is serious. Routine preoperative methods to assess airway such as the interincisor distance, Mallampati classification, and the upper lip bite test have a certain risk of upper respiratory tract exposure and virus spread. The condyle-tragus maximal distance can be used to assess the airway, and the assessment method does not require the patient to expose the upper respiratory tract, but its value in predicting difficult laryngoscopy compared to other indicators (Mallampati classification, interincisor distance, and upper lip bite test) remains unknown. The purpose of this study was to observe the value of condyle-tragus maximal distance to predict difficult laryngoscopy, and provide a new idea for preoperative airway assessment during epidemic. Methods: We enrolled adult patients who underwent general anesthesia and tracheal intubation. The interincisor distance, Mallampati test result, upper lip bite test result, and the condyle-tragus maximal distance of each patient were evaluated prior to the initiation of anesthesia. The primary outcome was difficult laryngoscopy defined as the Cormack-Lehane Level > grade 2. Results: A total of 304 patients were successfully included in the study ,39 patients were identified as difficult laryngoscopy. The correlation between the condyle-tragus maximal distance and Cormack-Lehane Level was the highest (Spearman correlation coefficient, -0.317; P＜0.001), and the area under the ROC curve was the highest (AUC：0.699,P＜0.01). The condyle-tragus maximal distance Conclusion: Compared with the interincisor distance , Mallampati classification and the upper lip bite test, the condyle-tragus maximal distance has higher value in predicting difficult laryngoscopy, which can become a safer airway assessment method during the epidemic of COVID-19. Trial registration: The study was registered on October 21, 2019 in the Chinese Clinical Trial Registry (ChiCTR1900026775).

Objective We investigated the “BURP” maneuver’s effect on the association between difficult laryngoscopy and difficult intubation, and predictors of a difficult airway. Methods Adult patients who underwent general anesthesia and tracheal intubation from September 2016 to May 2018 were included. The “BURP” maneuver was performed when glottic exposure was classified as Cormack–Lehane grade 3 or 4, suggesting difficult laryngoscopy. The thyromental distance, modified Mallampati score, and interincisor distance were assessed before anesthesia. Results Among this study’s 2028 patients, the “BURP” maneuver decreased difficult laryngoscopies from 428 (21.1%) to 124 (6.1%) cases and increased the difficult intubation to difficult laryngoscopy ratio from 53/428 (12.4%) to 52/124 (41.9%). For laryngoscopies classified as difficult without the “BURP” maneuver, the area under the curve (AUC) of the thyromental distance, modified Mallampati score, and interincisor distance was 0.60, 0.57, and 0.66, respectively. In difficult laryngoscopies using the “BURP” maneuver, the AUC of the thyromental distance, modified Mallampati score, and interincisor distance was 0.71, 0.67, and 0.76, respectively. Conclusions The “BURP” maneuver improves the laryngoscopic view and assists in difficult laryngoscopies. Compared with difficult laryngoscopies without the “BURP” maneuver, those with the “BURP” maneuver are more closely associated with difficult intubations and are more predictable. Trial registration: www.chictr.org.cn identifier: ChiCTR-ROC- 16009050.

Ultrasonography (USG) allows a new approach to the airway in anaesthesia and intensive care. USG visualises the airway from the mouth to the lungs. By exploring the entire airway, USG proposes new criteria (1) to assess the risk of difficult laryngoscopy, (2) to anticipate the management of a difficult airway, (3) to confirm the position of the endotracheal tube (ETT), and (4) to confirm that the lungs are effectively ventilated. Intraoperatively, USG may also help to resolve acute ventilatory problems such as pneumothorax, delayed selective bronchial intubation after patient positioning (Trendelenburg, prone or lateral position) or acute pulmonary oedema.

Background Children with microtia may experience difficult laryngoscopy because the ear and the mandible develop from the first and second bronchial arches and clefts. Methods In this prospective observational study, we enrolled 166 patients (6-14 years old) with microtia scheduled for auricular reconstruction with autologous costal cartilage framework. Airway of the subjects was assessed preoperatively with the Modified Mallampati classification, Thyromental distance, Interincisor gap, Forward protrusion of the mandible and Horizontal length of the mandible. Anesthesiologist performed the direct laryngoscopy. Difficult laryngoscopy was classified as grade III or IV based on the Cormack-Lehane classification. Results A total of 166 patients completed the study, including 158 (95%) isolated microtia patients and 8 (5%) hemifacial microsomia patients. The incidence of difficult laryngoscopy was 34/166 (20.5%) in all patients, 3/8 (37.5%) in hemifacial microsomia patients, 31/158 (19.6%) in isolated microtia patients (P=0.35). Multivariate logistic regression shows that Thyromental distance, Interincisor gap, Forward protrusion of the mandible are all independent predictors of difficult laryngoscopy. The sensitivity and specificity of each predictor were: Thyromental distance (82.35%, 89.39%), Interincisor gap (58.82%, 86.36%), and Forward protrusion (17.65%, 97.73%), respectively. The cutoff values of Thyromental distance and Interincisor gap for prediction of difficult laryngoscopy were 4.0 cm and 3.3 cm. The best combination of predictors was Thyromental distance/Interincisor gap/Forward protrusion of the mandible with a sensitivity of 94.12% and specificity of 86.36%. Conclusions The combination of Thyromental distance, Interincisor gap, and Forward protrusion of the mandible is the optimal assessment to predict difficult laryngoscopy in school-aged patients with microtia.

Objective: Ensuring airway security carries the utmost importance in anesthesia. Specific predictive tests or findings for difficult airway are not defined for children under 3 years old. This study is aimed at finding out the value of anthropometric measurements in the prediction of difficult laryngoscopy and intubation in children by comparing them to direct laryngoscopic evaluation of Cormack-Lehane test and intubation evaluation of intubation Difficulty Scale.", Method: A total of 108 patients (aged 0-3 years), undergoing elective surgery were included in this study. Patients with known syndrome, facial anomaly, Anesthesiologists Physical Status Classification Class >2, and laryngeal mask airway were excluded from the study. Demographic data, head circumference, weight, height measurements, body mass index and percentile values were recorded by a pediatric surgeon in the preoperative period. During laryngoscopy and intubation evaluations were made using Cormack-Lehane Score and intubation Difficulty Scale and recorded by a blinded resient. All recorded parameters were compared with Cormack-Lehane and intubation Difficulty Scale scores., Results: When all parameters were compared with CL Grade I-II-III, IDS scores; a statistically significant difference was found between age and head circumference and CL Grade I, II (p, Conclusion: Anthropometric measurements are not predictive for difficult direct laryngoscopy and difficult intubation in pediatric patients. The potentiality of difficult direct laryngoscopy could be higher in boys than girls and in children with low weight percentile.

Nuestro objetivo fue evaluar la utilidad de cinco mediciones ecográficas para predecir una laringoscopia difícil (LD). Estudio observacional prospectivo. Se incluyeron 50 pacientes programados para cirugía bajo anestesia general que precisaron intubación orotraqueal con laringoscopia clásica en el Hospital Universitario de Jaén (España). Se obtuvieron variables sociodemográficas, test clásicos de predicción de LD y mediciones ecográficas del tejido blando anterior del cuello desde la piel al hueso hioides (DSH), epiglotis (DSE) y glotis (DSG), así como 2 mediciones derivadas: DSH+DSE y DSE-DSG. La DSE y la DSE-DSG obtuvieron la mayor precisión diagnóstica (AUC de 0,79 y 0,82, respectivamente). Una DSE ≥3cm, y una DSE-DSG ≥1,9cm obtuvieron un valor predictivo positivo del 69,23% y del 78,57% para predecir una LD. El análisis multivariante avaló que la inclusión de ambos parámetros en modelos con pruebas clásicas (Test de Mallampati, distancia tiromentoniana y test de mordida) podrían mejorar la detección preoperatoria de LD. Our objective was to evaluate the usefulness of five ultrasound measurements to predict a difficult laryngoscopy (DL). Prospective observational study. 50 patients underwent scheduled surgery under general anesthesia with orotracheal intubation with classical laryngoscopy at the University Hospital of Jaén (Spain). Sociodemographic variables, classic preintubation screening tests and ultrasound measurements of the neck soft tissue from skin to hyoid (DSH), epiglottis (DSE) and glottis (DSG) were obtained, as well as two measurements derived from the above: DSH + DSE and DSE − DSG The DSE and the DSE-DSG obtained the highest diagnostic accuracy (AUC of 0.79 and 0.82, respectively). A DSE ≥3cm, and a DSE-DSG ≥1.9cm obtained a positive predictive value of 69.23% and 78.57% to predict a DL. The multivariate analysis confirmed that the inclusion of both parameters in models with classic tests (Modified Mallampati score, thyromental distance and upper lip bite test) could improve preoperative detection of a DL. Tesis Univ. Jaén. Departamento de Ciencias de la Salud. leída el 28 de octubre de 2020.

BACKGROUND Patients presenting for coronary artery bypass graft surgery can have higher incidence of difficult airway. Awareness about the incidence and predictors of difficult airway in CABG patients will help the anaesthesia provider in being adequately prepared for management of a difficult airway situation thereby reducing the laryngoscopy related adverse events on myocardial oxygenation. MATERIALS AND METHODS 100 consecutive patients scheduled for CABG under general anaesthesia were enrolled. Age, gender, weight, modified Mallampati class, neck extension, thyromental distance, diabetes mellitus and extent of coronary artery involvement determined by CAG were the study variables. Patients were classified as either having difficult laryngoscopy, or not, as the outcome variable. Associations between these were measured using appropriate statistical tests. RESULTS Analysis showed significant association between Mallampati class, number of coronary vessels involved, and diabetes mellitus. Mallampati class 3 or 4, triple vessel disease as evidenced by preoperative coronary angiogram and presence of diabetes mellitus were found to predict more chances of encountering difficult laryngoscopy. CONCLUSION 13% of patients posted for CABG had difficult laryngoscopy. Advanced age and obesity were not found to be of significance in our population of patients posted for CABG. Mallampati class, presence of diabetes mellitus and more extensive coronary vessel involvement where shown to predict more probability of difficult laryngoscopy in patients presenting for CABG.

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.

Objective: The aim of this study was to compare the ultrasonography (USG) measurements of anterior neck soft tissue and other clinical screening tests used to evaluate difficult laryngoscopy in mor...

Background: Unanticipated difficult tracheal intubation remains a primary concern of anaesthesiologists and upper lip bite test (ULBT) is one of the assessments used in predicting difficult intubation. In this study, we aimed to check the utility of lateral neck X-ray measurements in improving the diagnostic value of the ULBT. Methods: In a prospective study conducted from January 2007 until December 2010, we recorded personal and demographic data of 4500 patients who entered the study and subjected them to standard lateral neck radiography. Before the induction of anaesthesia, clinical examination and ULBT results were recorded and during induction of anaesthesia laryngoscopic grading was evaluated and recorded in questionnaires. All the compiled data were analysed by SPSS 14.0 (SPSS Inc., Chicago, IL, USA) software. Diagnostic value for each test was calculated and compared. Results: Negative predictive values (NPVs) were high in all tests. ULBT had the highest specificity and NPV compared with the other tests. The positive predictive value for all the tests had been low, but marginally high in the ULBT. Conclusion: Although all the tests used had relatively acceptable predictive values, combination of tests appeared to be more predictive. Highest sensitivities were observed with ULBT, mandibulohyoid distance and thyromental distance respectively. Use of radiological parameters may not be suitable as screening tools, but may help in anticipating and preparing for a difficult scenario.

BACKGROUND Airway management is of prime importance to the anaesthesiologists. Unanticipated difficult laryngoscopy and endotracheal intubation remains a primary concern for the anaesthesiologists. The reported incidence of a difficult laryngoscopy or endotracheal intubation varies from 1.5% to 13% in patients undergoing surgery. Failure to intubate is detected in 0.05-0.35% of the patients. Thus, preoperative airway assessment is of pivotal importance for the anaesthesiologist to predict difficult intubation. The aim of the study is to study the usefulness of two different airway assessment predictors, a clinical and radiological tool to predict difficult intubation. MATERIALS AND METHODS Two hundred and eight patients in the age group of 15-75 years of either sex were included in the study. We assessed the clinical variable: modified Mallampati classification and radiological variable: the atlanto-occipital distance, in all the patients. Patients with tumours or malformations of head and neck and oral cavity, edentulous patients, pregnant patients and those requiring emergency surgeries were excluded. A Cormack-Lehane grade of I and II were considered as easy intubation and III and IV were considered as difficult intubation. RESULTS Thirty eight patients had difficult intubation. The sensitivity and specificity of the clinical model were found to be 97.2% and 95.3%, respectively. The sensitivity and specificity of the combined clinical and radiological model were found to be 100% and 95.3%, respectively. The area below the ROC curves measures the probability of the correct prediction of the clinical and the combined models. It was found to be 0.992 and 0.993, respectively. This means that the clinical and combined models correctly predicted the outcome with a probability of 99.2% and 99.3%, respectively. CONCLUSION From this study, we found that- 1. Clinical models- Modified Mallampati classification is an important predictor of difficult intubation. 2. Radiological imaging- Atlanto-occipital distance is also an important predictor, but with less sensitivity than the clinical model. 3. The radiological predictor is of more value when it is combined with clinical variable, but of less value as a single predictor.

BACKGROUND The aim of this study is to evaluate the various clinical parameters of airway assessment and their ability to predict difficult laryngoscopy and intubation in diabetic patients as compared to nondiabetic patients. MATERIALS AND METHODS Out of 120 patients, 60 diabetics (group-D) and 60 nondiabetics (group-N) were studied preoperatively for various airway indices such as the modified Mallampati Test (MPC), Thyromental Distance (TMD), Degree of Head Extension (HE), the Palm Print Index (PP) and the Prayer Sign (PS) and their corresponding Cormack-Lehane scores (CL) were noted. The two groups were studied using chi-square tests. p

We report a case of difficult endotracheal intubation in a patient with Treacher Collins syndrome. A sixteen-year-old female patient scheduled for general anesthesia had a displaced palatal tooth that interfered with laryngoscope insertion into the pharyngeal space. To address this problem, we successfully performed endotracheal intubation using a fiberscope while elevating the epiglottic vallecula using a King Vision™ video laryngoscope. A later operation was performed after tooth extraction without difficult laryngoscopy. Our experience stresses the importance of removing obstructions to laryngoscopic inspection prior to general anesthesia.

Introduction: Currently, various methods are being used for determining difficult laryngoscopy. The present study aimed to compare the acromioaxillosuprasternal notch index function with the old head and neck anatomic criteria in predicting difficult laryngoscopy with respect to trachea intubation under general anesthesia in children. Materials and Methods: In this cross-sectional study, 379 children under intubation with general anesthesia entered the study. Patients were divided into two groups: easy laryngoscopy (grades 1 and 2) and difficult laryngoscopy (grades 3 and 4) based on Cormack-Lehane score. The thyromental distance systems, height to thyromental distance, Upper-Lip-Bite test, neck circumference, and acromioaxillosuprasternal notch index were studied and compared. Results: Laryngoscopy was difficult in 48 subjects (38 were grade 3 and 10 were grade 4). Interestingly, no significant difference was detected between easy and difficult laryngoscopies based on the thyromental distance, neck circumference, height to thyromental distance, and acromioaxillosuprasternal notch index (P>0.05). height to thyromental distance , acromioaxillosuprasternal notch index , and neck circumference have a sensitivity of 32.2%, 47.9%, 51.1%, respectively, and the specificity was 52.7%, 45.6%, and 48.9%, respectively. Conclusion: Neck circumference and acromioaxillosuprasternal notch index outperform the height to thyromental distance. On the other hand, Modified Mallampati test is better than Upper-Lip-Bite test in determining difficult laryngoscopy in children.

Background Several methods have been used to predict difficult tracheal intubation. Among recently suggested methods, the upper lip bite test (ULBT) could serve as a good predictor. Soft tissue and skeletal hard tissue profiles are affected by many factors including ethnicity. We aimed to assess the clinical utility of the ULBT in Koreans while considering ethnic differences. Methods Three-hundred-forty-four Korean patients undergoing general anesthesia with orotracheal intubation were included. Preoperatively, we recorded the patient’s Modified Mallampati (MMT) classification, ULBT ratings, and the Cormack–Lehane grade. Results The area under the receiver operating characteristic (ROC) curve (AUC) was lower for the ULBT than the MMT (95% confidence interval: 0.0697–0.191, p

Objective. The aim of the present preliminary study was to assess whether the sternomental distance ratio (SMDR) could be suitable as a predictor of difficult laryngoscopy, in both normal surgical patients and patients scheduled to undergo thyroid tumor surgery. Methods. Two hundred and twenty-one consecutive adult patients (among them 122 patients with presumed normal airways and 33 patients with thyroid tumors), scheduled to undergo elective surgery under general anesthesia, were included in this study. Physical and airway characteristics, SMDR, difficult laryngoscopy (using Cormack-Lehane scale) and any kind of assisted intubation were assessed. Results. Decreased SMDR demonstrated a strong correlation with difficult laryn­goscopy in both thyroid tumor (Kendall’s tau-b -0.578 (P=0.004) and normal patients -0.362 (P1.9 and 33% at SMDR Conclu­sions. Α SMDR>1.9 indicates an easy laryngoscopy, whereas SMDR