Thyromental Distance Research Articles

Perioperative complications of pediatric otorhinolaryngological operations.

Background:The identification of risk factors for the development of perioperative complications is one of the most important problems of pediatric anesthesiology.Purpose:To identify risk factors for the development of perioperative complications in children undergoing ambulatory surgical interventions on ENT organs.Methods:Total of 141 patients were examined at the age from 7 to 17 years. Depending on the presence of complications all patients were divided into three groups: «No complications» (n = 64), «One complication» (n = 55) and «Two or more complications» (n = 22). The study was carried out in the following areas: Preoperative clinical status, intraoperative and postoperative complications. The severity of nasal breathing disorders was determined rhinomanometrically. 31 children underwent somnography. In the study of heart rate variability was evaluated. Intraoperative complications included: Cardiac arrhythmias, arterial hypertension and desaturation less than 90%. Postoperative complications included: Cardiorespiratory complications, pain, delirium, postoperative nausea and vomiting.Results:The most significant complication in the intraoperative period is desaturation below 90%, in the postoperative period they are pain, nausea and vomiting. Risk factors for the development of complications in the perioperative period are a decrease in the thyromental distance, hyperplasia of the tonsils of the third degree, Malampati score ≥ to 2 points, parents' bad habits, combined neurological and respiratory pathologies in a child, an assessment of the class «allergology» of the ASPOND scale is not less than 180 points and the prevalence of vagal influences.Conclusions:The obtained results indicate that the presence of risk factors for perioperative complications during operations on ENT organs in children are associated with the initial autonomic status and the predominance of the parasympathetic nervous system as well as with clinical markers.

Comparative evaluation of conventional to left molar and right molar laryngoscopy and endotracheal intubation

Background: Difficulty in visualizing the glottis may cause difficulty, even failure in endotracheal intubation leading to catastrophes. Difficult laryngoscopy is frequently overcome by using molar approach for laryngoscopy combined with optimal external laryngeal manipulation (OELM). The present study was planned to compare conventional midline approach of laryngoscopy to left molar and right molar approach of laryngoccopy (using Macintosh blade) for endotracheal intubation Material and Methods: This prospective randomized double blind controlled study was conducted on 120 patients of 18-60 years age, belonging to ASA grade I and II of either sex, posted for elective surgery under general endotracheal anaesthesia. Depending on the approach of laryngoscopy used, the patients were randomly divided into three groups of 40 each into Group M (midline approach), Group L (left molar approach) and Group R (right molar approach). Predictors of difficult intubation (Modified Mallampati grading, Thyromental distance, abnormal Dentition) and their association with unsuccessful intubation, Cormack Lehane grading, attempts of intubation, duration of intubation, success rate of intubation, adjuvant measures needed (stylet, retraction of mouth) for intubation were noted. Results: Patients having predictors of difficult intubation had significant risk of unsuccessful intubation with midline approach (p=0.01 for MPG III/IV, p=0.04 for TMD

The Impact of Sevoflurane and Propofol Anesthetic Induction on Bag Mask Ventilation in Surgical Patients with High Body Mass Index.

Background and Aims:Obesity is associated with restrictive ventilatory pattern which causes rapid oxygen desaturation. Although obesity is considered as a risk factor for difficult airway management, failure to achieve effective bag mask ventilation (BMV) can be catastrophic. This study tried to assess the effect of both propofol and sevoflurane on the efficacy of BMV during anesthetic induction in obese patients.Patients and Methods:A total of 200 cases were included, and they were randomly divided into two equal groups; Group S which included 100 cases who underwent sevoflurane induction, and Group P which included the remaining 100 cases who underwent propofol induction.Results:No statistically significant difference was detected between the two groups regarding patient and air way characteristics (P > 0.05). Difficult BMV (DBMV) was encountered in 19% and 37% of cases in Groups S and P, respectively. The incidence of DBMV was significantly increased in the P group (P = 0.005). Furthermore, the severity of difficulty was more marked in the P group. Logistic regression analysis revealed that thyromental distance, presence of macroglossia, presence of beard, lack of teeth, history of snoring, as well as propofol induction were risk factors for DBMV.Conclusion:Sevoflurane can facilitate BMV and provide better intubation conditions in comparison to propofol during anesthetic induction in morbidly obese patients. Moreover, decreased thyromental distance, presence of macroglossia and beard, lack of teeth, and history of snoring are considered preoperative indicators of DBMV.

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

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

24. Predictors of Difficult Laryngoscopy: Comparison of Ratio of Height to Thyromental Distance, Upper Lip Bite Test and Mallampati Grading, A Comparative Analytical Study

24. Predictors of Difficult Laryngoscopy: Comparison of Ratio of Height to Thyromental Distance, Upper Lip Bite Test and Mallampati Grading, A Comparative Analytical Study

18. Comparison of Upper Lip Bite Test with the Measurement of Thyromental Distance for the Prediction of Difficult Intubation: An Observational Study

18. Comparison of Upper Lip Bite Test with the Measurement of Thyromental Distance for the Prediction of Difficult Intubation: An Observational Study

The Evaluation of Upper Airway: Point of Care Ultrasound vs. Conventional Tests

Objective: The ultrasound-guided interventions have gained widespread popularity in several aspects of anesthesia practice. In this study, we aimed to compare the preoperative evaluation tests and sonographic measurements of the upper airway for the prediction of a potentially difficult airway.
 Material and Methods: In this prospective observational study, we enrolled 136 adult patients undergoing elective surgery under general anesthesia. The Modified Mallampati classification, thyromental distance, sternomental distance, and Cormack-Lehane scores were recorded. Sonographic measurements included pre-epiglottic space (PES), the distance between the midpoints of vocal cords and epiglottis (EVC). The ratio was interpreted. Main outcome is to determine the sensitivity and specificity of the upper airway ultrasound for the prediction of a potentially difficult airway.
 Results: There was no statistically significant relationship between body mass index value and thyromental distance, Thyromental/Sternomental Ratio and PES/EVC ratio, Cormack-Lehane, Mallampati classification and thyromental/sternomental distance ratio (p>0.05). The sonographic measurements of airway have no significance to predict the difficult intubation and the comparison between PES, EVC and the PES/EVC ratio and assessment tests (Cormack-Lehane, Mallampati classification, thyromental and sternomental distances) was insignificant. The sternomental distance measurement was predictive for the difficult airway only in patients having body mass index more than 31.6 kg m-2.
 Conclusion: Ultrasound is a useful tool for identifying the upper airway prior to anesthesia but the validity for the prediction of difficult airway is not clear. By increasing the clinical experiences and further investigations, a greater insight into its use will be gained.

Accuracy of thyromental height test for predicting difficult intubation in elderly.

Studies of the accuracy of different airway tests are lacking in elderly. We evaluated and compared the accuracy of thyromental height in predicting difficult intubation in relation to the other traditional airway tests in elderly. We included 120 patients aged ≥ 65years scheduled for general anesthesia with tracheal intubation. Thyromental height, modified Mallampati test, thyromental distance and sternomental distance were evaluated. Cormack-Lehane grade > 2 was considered difficult laryngoscopy. Difficult tracheal intubation was considered if successful intubation required more than 2 attempts. The accuracy of different tests in predicting difficult intubation and difficult laryngoscopy were evaluated through area under receiver operating characteristic (AUROC) curves. Univariate and multivariate analyses were conducted to identify risk factors for difficult intubation and difficult laryngoscopy. Our cohort had a mean age of 71(7) years. We encountered difficult laryngoscopy in 15/120 (12%) patients, difficult intubation in 20/120 (17%) patients, and failed laryngoscopy requiring alternative methods for securing the airway in 3/120 (3%) patients. For predicting difficult intubation, thyromental height and modified Mallampati test showed the highest accuracy AUROC (95% confidence interval): 0.9 (0.83-0.95), cut-off value ≤ 5.9cm, and AUROC (95% confidence interval): 0.89 (0.82-0.94), cut-off value > 2, respectively. Low thyromental height and high modified Mallampati test were the only independent risk factors for difficult laryngoscopy and difficult intubation. In elderly scheduled for elective procedure, both thyromental height and modified Mallampati tests showed good accuracy in predicting difficult intubation and difficult laryngoscopy, whilst thyromental distance and sternomental distance were poor predictors.

Predictive factors for sleep apnoea in patients on opioids for chronic pain

BackgroundThe risk of death is elevated in patients taking opioids for chronic non-cancer pain. Respiratory depression is the main cause of death due to opioids and sleep apnoea is an...

TO STUDY THE CORRELATION BETWEEN SONOGRAPHIC MODIFICATION OF CORMACK LEHANE SCORING WITH ACTUAL CL GRADING DURING DIRECT LARYNGOSCOPY

Background: Airway assessment is an essential aspect of preanaesthetic assessment. Presently, prediction of difficult airway is based on clinical assessment of airway.
 Methods: Prospective Observational conducted at Department of Anesthesiology, Dr. RPGMC Kangra at Tanda, Himachal Pradesh.
 Results: It was observed that 44% patients (n=88) were in grade 2 followed by 27 % (n=54) in grade 1, grade 3 was observed in 24.5% patients (n=49) whereas Cormack Lehane grade 4 was seen in 4.5% patients (n=9)
 Conclusion: The thyromental distance was more than 6.5 cm in the majority of patients (87.5%) while 12.5% had a thyromental distance less than 6.5 cm. There was a significant difference in Thyromental distance between different Cormack Lehane grades (P=0.001)
 Keywords: Ultrasound, endotracheal intubation, direct laryngoscopy

Comparison of Laryngoscopic Views betweenC-MAC™ and Conventional Laryngoscopy in Patients with Multiple Preoperative Prognostic Criteria of Difficult Intubation. An Observational Cross-Sectional Study.

Background and Objectives: Video laryngoscopy has been proven useful under difficult airway scenarios, but it is unclear whether anticipated improvement of visualization is related to specific difficult intubation prognostic factors. The present study evaluated the change in laryngoscopic view between conventional and C-MAC® laryngoscopy and the presence of multiple difficult intubation risk factors. Materials and Methods: Patients scheduled for elective surgery with >2 difficult intubation factors, (Mallampati, thyromental distance (TMD), interinscisor gap, buck teeth, upper lip bite test, cervical motility, body mass index (BMI)) were eligible. Patients underwent direct laryngoscopy (DL) followed by C-MAC™ laryngoscopy (VL) and intubation. Change of view between DL and VL, time for best view, intubation difficulty scale (IDS) and correlation between prognostic factors, laryngoscopic view improvement, and IDS were measured. Results: One-hundred and seventy-six patients completed the study. VL lead to fewer Cormarck–Lehane (C/L) III-IV, compared to DL (13.6% versus 54.6%, p < 0.001). The time to best view was also shorter (VL: 10.82 s, DL: 12.08 s, p = 0.19). Mallampati III-IV and TMD ≤ 6 cm were related to improvement of C/L between DL and VL. Logistic regression showed these two factors to be a significant risk factor of the glottis view change (p = 0.006, AUC-ROC = 0.57, 95% CI: 0.47–0.66). 175/176 patients were intubated with VL. 108/176 were graded as 0 < IDS ≤ 5 and 12/176 as IDS > 5. IDS was only correlated to the VL view (p < 0.0001). Conclusion: VL improved laryngoscopic view in patients with multiple factors of difficult intubation. Mallampati and TMD were related to the improved view. However, intubation difficulty was only related to the VL view and not to prognostic factors.

The anesthesia airway evaluation: Correlation with sleep endoscopy findings.

Drug-induced sleep endoscopy (DISE) is a cost-effective, safe, and reliable tool to evaluate obstructive sleep apnea (OSA) patients by revealing upper airway sites, patterns, and severity of obstruction. DISE provides valuable data because reliable evaluation of the OSA airway while awake has remained elusive. Few studies (with mixed results) have analyzed the correlation between pre-operation, awake airway assessments routinely performed by anesthesia and DISE results. Preoperative anesthesia evaluation records and subsequent DISE reports were obtained for 99 adult patients undergoing DISE between 2016 and 2018. All patients carried the diagnosis of OSA, based on polysomnography. Anesthesia-collected variables were compared with DISE findings in an effort to determine if commonly-utilized physical exam findings correlated to patterns of upper airway collapse observed on sleep endoscopy. Most anesthesia preoperative evaluation variables were not found to be predictive of any identifiable patterns of collapse on DISE, including Mallampati score, ability to prognath, and overall airway assessment score. Obesity did not correlate with circumferential collapse at the velopharynx, or to multi-level collapse. Thyromental distance <6.5cm was found to be statistically correlated to total epiglottic collapse (E=2+). Friedman tongue position scores were found to be correlated to velopharyngeal collapse (p<0.05). Anesthesia airway assessment algorithms and physical exam findings do not correlate well with findings on sleep endoscopy. DISE remains the gold standard for evaluating levels of collapse and operative planning in the OSA population.

Correlation of Bedside Airway Screening Tests With Airway Obstruction During Drug-Induced Sleep Endoscopy

Obstructive sleep apnoea hypopnoea syndrome associated with obesity poses major perioperative airway challenge. Drug-induced sleep endoscopy (DISE), is a real-time upper airway flexible fiberoptic nasoendoscopy in awake and sedation/anaesthesia-induced sleep. The aim of current study was to assess the correlation of bedside airway screening tests with level of obstruction during DISE. Study was performed in endoscopy suite. Parameters calculated in 40 study group patients were Berlin questionnaire responses, Apnea hypopnea index (AHI), interincisor distance, Mallampati classification (MPC), neck circumference (NC), thyromental distance (TMD), NC/TMD ratio, sternomental distance (SMD), upper lip bite test, lateral cephalometry derived gonial angle and mentohyoid distance (MHD), Muller’s manoeuvre during awake nasoendoscopy, Croft–Pringle grade of airway obstruction during DISE and effect of jaw thrust. All patients were American Society of Anesthesiologists physical status 1 and 2 with AHI > 30. Positive responses to Berlin questionnaire, body mass index and AHI increased with increasing grade of DISE. DISE grades 1–5 were observed in 0% (0), 5% (2), 37.5% (15), 27.5% (11) and 30% (12) patients respectively. Muller’s manoeuvre showed lateral wall collapse in 40% (16) patients and concentric collapse in 40% (16) patients. Airway patency improved with jaw thrust in 60% (24) patients. Significant association of DISE was found with MPC (p = 0.028), TMD (p = 0.003), MHD (p = 0.008) and NC/TMD ratio (p = 0.002), effect of Muller’s manoeuvre (p =0.002), and effect of jaw thrust (p = 0.000). Bedside screening tests MPC, TMD, NC/TMD ratio and MHD correlate significantly with level of obstruction during DISE.

Evaluation of difficult airway in paediatric population ranging from 5-12 years age group

Background: The aim of this study is to predict difficult airway on the basis of various airway assessment parameter in the paediatric population between 5-12 years age group. To assess the value of modified Mallampati test (MMT), upper-lip-bite test (ULBT), thyromental distance (TMD), ratio of height to thyromental distance (RHTMD) from which Cormack Lehane grade was derived to predict difficult airway i.e. difficult intubation in paediatric patients ranging from 5-12 years age. Material and Methods: 100 ASA grade I & II paediatric patients of either sex between the age group of 5-12 years posted for elective surgery under general anaesthesia requiring endotracheal intubation were included in the study. Modified Mallampati test, upper lip bite test, thyromental distance and ratio of height to thyromental distance of the patients were measured and recorded. All the distances were measured with the help of a flexible measuring tape so as to measure the distances accurately. Results: Modified Mallampati test has the highest sensitivity (75%) and specificity (92.05%) among all the other screening tests. It also has high positive predictive value (56.25%), negative predictive value (96.43%) and diagnostic accuracy (90%). Upper Lip Bite test has high specificity (79.55%) and negative predictive value (93.33%) with high diagnostic accuracy (77%). It has a sensitivity of 58.33% which is similar to the sensitivity of thyromental distance and ratio of height to thyromental distance. Thyromental distance has high specificity (65.90%) with high negative predictive value (92.06%). Conclusion: Modified Mallampati test is a useful bedside screening test for predicting difficult intubation in patients between 5-12 years age group. The Upper Lip bite test and thyromental distance has high specificity with high negative predictive value and diagnostic accuracy. The ratio of height to thyromental distance is least useful predictor of airway assessment.

Description and comparison of the performance of the upper lip bite test, the ratio of height to thyromental distance and other methods of preoperative airway assessment in a Nigerian population – a pilot study

Background: The ability to reliably predict difficult intubation can prevent airway related adverse outcomes. The upper lip bite test (ULBT) and ratio of height to thyromental distance (RHTMD) are airway predictive tests that have been evaluated in Caucasian populations with promising results. This study determined the test performance of the ULBT and RHTMD and compared with commonly employed predictive tests (modified Mallampati [MMT], thyromental distance [TMD] and inter-incisor gap [IIG]) in adult Nigerians. Methods: This was a cross-sectional study. Two hundred and sixteen consecutive, consenting ASA I-III patients presenting for surgery and planned for general anaesthesia with endotracheal intubation over a six month period in our teaching hospital, had all five airway assessment tests (ULBT, RHTMD, MMT, TMD and IIG) assessed preoperatively. The Cormack and Lehane grading was used to determine easy or difficult visualisation of the larynx (EVL or DVL). Sensitivity, specificity, predictive values and likelihood ratios of the tests were determined. Results: The sensitivities, specificities, positive and negative predictive values and positive and negative likelihood ratios respectively for the tests were: ULBT (11.8%, 99.0%, 50.0%, 92.9%, 11.71 and 0.89), RHTMD (35.3%, 92.5%, 28.6%, 94.4%, 4.68 and 0.70), TMD (29.4%, 97.5%, 50.0%, 94.2%, 11.71 and 0.72), MMT (52.9%, 86.4%, 25.0%, 95.6%, 3.90 and 0.54), and IIG (11.8%, 97.0%, 25.0%, 92.8%, 3.90 and 0.91). Conclusion: The modified Mallampati test had the highest sensitivity in this study, however all the tests evaluated showed only low to moderate sensitivity. The ULBT and RHTMD had low sensitivities in this population. However, based on the high positive likelihood ratios of the ULBT and the TMD, whenever positive, these tests do show a high probability of DVL and these two tests would probably perform similarly in this population. Anthropometric differences may account for differences in performance of preoperative airway assessment tests in various populations.

Anesthesia management of cervical chordoma resection: A case report

Chordoma is a slow-growing, locally invasive, lowgrade malignant tumor with a prevalence of one in 100 000, accounting for 1%-4% of all malignant bone tumors. At present, it is considered that chordoma originates from ectopic embryonic chordal tissue and can occur in any part of the spine from the skull base to the sacrum. About 50% of chordoma occurs in the sacrococcygeal region, about 30% in the skull base, and the rest occurs in the active spinal region. Cervical chordoma is rare, but it may be accompanied by difficult airways. The tumors compress the pharynx and throat forward, which can cause upper airway obstruction. If the anesthesia is not properly handled, the patient may die of asphyxia. The core issues of airway management during the perioperative period of cervical chordoma surgery involve three main parts: preoperative airway evaluation, airway management and extubation management. Difficult airway assessment often relies on physical examination indicators, such as inter-incisor gap, thyromental distance, neck circumference, Mallampati test, etc. But the accuracy is insufficient. The application of imaging examination in the observation of different tissues can make up for the inaccurate evaluation of the internal structure of the airway. Because chordoma destroys cervical vertebral body and accessories, cervical stability is impaired. Excessive cervical vertebral extention should be avoided during tracheal intubation to prevent severe compression of the spinal cord. It is better to fix the head by an assistant and perform neutral tracheal intubation. Considering that the patient with a difficult airway that could be predicted before operation, the strategy of tracheal intubation under conscious sedation with topical anesthesia was selected. After sedation and topical anesthesia, the patient was successfully intubated with optical stylet. After operation, the patient returned to ICU with tracheal catheter. On the 4th day after operation, the tracheal tube was pulled out. On the 5th day after operation, the patient was transferred to the orthopaedic ward and discharged on the 7th day after operation. It is of great significance to establish specific strategies for such operations to reduce related complications, speed up post-operative rehabilitation and save medical resources. We reported the anesthetic management of cervical chordoma cured in Peking University Third Hospital.

A Study to Predict Difficult Intubation Using Simple Non-invasive test: A Prospective Observational Study

Background: Airway Management is prime importance to the anaesthesiologist of all the anaesthetic deaths 30 % to 40 % are attributed to the inability to manage a difficult airway. The various simple bedside predictors of difficult airway like Mallampati test, Upper lip bite test, Thyromental, Hyomental, Thyrosternal & Sternomental distances, mandibular length, Neck circumferences etc. are easy to perform with No extra cost or inconvenience to patients. Aim: To assess the predictability of Upper lip bite test, Hyomental distance, Thyromental distance, Thyrosternal distance & Mandibular length. Objective: 1) To find out the best predictor of difficult intubation amongst the Upper Lip Bite Test, Hyomental Distance, Thyromental Distance, Thyrosternal Distance & Mandibular Length on the basis of the test. Methods: This is a prospective observational study of 110 patients are randomly selected & age caring between 20 to 59 yrs both male and female are presented in anaesthesia of routine per anaesthetic check-up. After from mouth opening & mallampati test which are routinely done airway assessment included ULBT, HMD, TMD, TSD & ML will be done. Results: After analysing study state that the age (P = 0.031) were significant , & sex (P = 0.213) ASA (P = 0.091) were not significant with difficult intubation on the basis of Cormack lehane grading. All these factors were applicant on next set of 110 patients to found sensitivity & specificity to be ULBT ( SE = 50.00%, SP =100.00%), HMD (SE = 10.00%, SP = 97.00%), TSD (SE = 0.00%, SP = 97.00%), ML (SE = 20.00%, SP = 97.00%) & TMD (SE = 70.00%, SP = 85.00%) respectively. Conclusions: Thyromental distance is the most important sensitive factors predicting difficult intubation on the basis of cormack lehane grading in indian patients.

Validity of Airway Assessment of the Thyromental Distance and Mallampati Test for Predicting Difficult Intubation

Validity of Airway Assessment of the Thyromental Distance and Mallampati Test for Predicting Difficult Intubation

Airway sonography fails to detect difficult laryngoscopy in an adult Veteran surgical population

ObjectiveTo evaluate ultrasound's utility to detect difficult laryngoscopy in a preoperative setting. MethodsThis single-site, prospective, cross-sectional, within-subjects study was performed at a Veterans Affairs Medical Center with 144 subjects. The sonographic independent variables included sonographic hyomental distance (HMD) and anterior neck thicknesses at the hyoid bone (HB), thyrohyoid membrane (THM), and vocal cords (VC). Additional independent variables were standard airway indicators of BMI, neck circumference, obstructive sleep apnea, snoring, abnormal upper teeth, jaw mobility, interincisor gap, Mallampati score, thyromental distance and neck range of motion. The outcome variable was the modified Cormack-Lehane Grade (CLG). ResultsThere was no significance found among the four sonographic measurements or their derived ratios in predicting difficult laryngoscopy. Correlation analysis between the sonographic measurements did find significance of the HMD:HB (p = 0.040) and the HB:THM (p = 0.44) ratios. However these ratios had a weak correlation at −0.172 and −0.168 respectively. Standard airway indicators did not demonstrate significance in predicting the difficult airway, sans obese patient with neck circumference (p = 0.016). DiscussionThis study demonstrated ultrasonography in predicting difficult laryngoscopy lacked utility. Ultrasound utilization as an efficacious means of difficult airway assessment requires further research with a larger sample size. Further studies using sonography on those patients with known difficult airways may provide data to determine if ultrasound has utility in predicting difficult laryngoscopy.

Accuracy of different anatomic landmark methods in determining size of nasopharyngeal airway

Objective To evaluate the accuracy of different anatomic landmark methods in determining the size of nasopharyngeal airway. Methods Fifty-two patients of both sexes, aged 16-60 yr, of American Society of Anesthesiologists physical status Ⅰ to Ⅲ, with body mass index of 18-30 kg/m2, scheduled for elective awake craniotomy for supratentorial tumors under sedation-awake-sedation anesthesia, were included. For each patient, the distance from the apex of nose to the right tragus (NT), distance from apex of nose to the right mandibular angle (NM), and thyro-mental distance (TM) were measured and marked on a transnasal tube correspondingly. The patients were placed in supine position without pillow, topical anesthesia (nasal mucosal surface) was performed with 2% lidocaine, and patients were sedated with midazolam, propofol and dexmedetomidine. When Observer′s Assessment of Alertness/Sedation Scale score was 2 or 3 points, the tube was transnasally inserted to each marked depth. When the three marked depths mentioned above were reached, the positions of the tube′s tip were checked using a fiberoptic bronchoscope and recorded as: above epiglottis (the tip of the tube was placed between the epiglottis and the free edge of soft palate) or below epiglottis (the tip of the tube placed at or beyond the epiglottis). Results When the depth reached the NT mark, the tube′s tip was above epiglottis in 14 cases (27%), and the tube′s tip was below epiglottis in 38 cases (73%). When the depth reached the NM mark, the tube′s tip was above epiglottis in 31 cases (60%), and the tube′s tip was below epiglottis in 21 cases (40%). When the depth reached the TM mark, the tube′s tip was above epiglottis in 52 cases (100%). Compared with the NM and NT methods, the TM method had a higher probability with the tube′s tip above epiglottis when used to determine the depth of insertion (P<0.01). Conclusion TM anatomic landmark method provides higher accuracy in determining the size of nasopharyngeal airway. Key words: Anatomic landmarks; Airway management