Difficult Visualization Of Larynx Research Articles

Comparison of acromio-axillo-suprasternal notch index with thyromental height test to predict difficult visualization of larynx

Background: Securing and maintaining a patent airway for the conduct of general anesthesia are a major concern for an anesthesiologist. Unanticipated difficult intubation in anesthetized patients is the main cause of morbidity or mortality. Several predictors are proposed to anticipate difficult tracheal intubation, but no predictor is found to be 100% accurate. Acromio-axillo-suprasternal notch index (AASI) is a recent addition to the list of predictors. Aims and Objectives: The current study compared the usefulness of AASI and thyromental height test (TMHT) as predictors of difficult visualization of larynx (DVL). Materials and Methods: Following approval by the Institutional Ethics Committee and CTRI registration, written informed consent was taken. The study was conducted on 300 patients aged 18–65 years belonging to American Society of Anesthesiologists’ physical status I and II, with modified Mallampati (MMP) Scores of 1 and 2, over a period of 6 months. Preoperatively all patient’s airway was evaluated using AASI and TMHT. The DVL during direct laryngoscopy was noted as assessed by Cormack and Lehane grading. We compared the sensitivity and specificity for DVL with regard to AASI and TMHT. Results: The incidence of unanticipated DVL was 14%. The sensitivity, specificity, positive predictive value, and negative predictive value of AASI were 86.4%, 38.1%, 89.6%, and 31.4%, respectively, and for TMHT, they were 94.6%, 4.8%, 85.9%, and 12.5%, respectively. Pearson correlation coefficient was r = −0.068 (P=0.243) when AASI was compared with TMHT. Conclusion: AASI was found to be less sensitive when compared to TMHT and there was statistically no significant correlation between the two parameters to predict the DVL.

A comparison of ratio of patient’s height to thyromental distance with modified mallampati test and upper lip bite test for prediction of difficult laryngoscopy

Various airway evaluation tests are performed to predict difficult intubation. The ratio of Height to thyromental distance has been reported to have a good predictability. This study tested the performance of ratio of height to thyromental distance and compared it with commonly performed airway evaluation tests: the modified Mallampati test and upper lip bite test. This descriptive study was conducted in 120 patients presenting for surgery under general anesthesia with endotracheal intubation. Preoperative airway assessment was done using Modified Mallampati test, upper lip bite test and ratio of height to thyromental distance. The Cormack and Lehane grading was done during laryngoscopy to determine easy or difficult visualization of larynx. Sensitivity, specificity, positive predictive value, negative predictive value and accuracy of three tests were calculated. Difficult laryngoscopy was seen in 9 patients (7.5%). The sensitivity, specificity, positive predictive value, negative predictive value respectively for the tests were modified Mallampati test (22.2%, 89.2%, 14.3% and 93.4%), upper lip bite test (22.2%, 100%, 100% and 94.1%), ratio of height to thyromental distance (77.8%, 95.5%, 58.3% and 94.16%). In conclusion, we found that the ratio of patient’s height to thyromental distance performed better than MMT and ULBT in predicting difficult visualization of larynx in our population.

Evaluation of ratio of height to thyromental distance as a predictor of difficult visualization of larynx: A prospective observational single center study

BackgroundRatio of height to thyromental distance (RHTMD) is a relatively new predictor of difficult visualization of larynx (DVL). Studies on Indian population are limited and none is carried out in the northeastern part of India. AimsThe primary aim was to assess the performance of RHTMD as a predictor of DVL and compare its predictive performance with modified Mallampati test. The secondary aim was to compare the performance of RHTMD with sterno-mental distance, inter-incisor distance and upper-lip bite test, as a predictor of DVL. We also aimed to evaluate the performance of RHTMD as a predictor of Intubation difficulty scale (IDS) > 5. MethodsIn this prospective, observer blinded, single center study, adult patients of either sex scheduled to receive general anaesthesia with tracheal intubation were enrolled after permission from institutional committee. RHTMD, modified Mallampati test, sterno-mental distance, inter-incisor distance and upper-lip bite test wereassessed pre-operatively by a single examiner trained in the airway indices but not involved in laryngoscopy. On the day of surgery, laryngoscopy was performed by a trainee anaesthesiologist with minimum two years of experience who was blinded to the airway indices noted by the examiner preoperatively. The Cormack-Lehane grading and subsequent difficulty in intubation as per Intubation difficult scale was noted. RHTMD≥23.5, inter-incisor distance ≤ 4 cm, sterno-mental distance ≤12.5 cmand upper lip bite test class 3 were considered as predictor of difficult laryngoscopy. ResultsThe incidence of DVL and difficult intubation in our study was 6.57% (4.85 %-8.82%, 95% CI) and 1.37% (0.68%–2.7%, 95% CI) respectively. The sensitivity of RHTMD, modified Mallampati test, sterno-mental distance, inter-incisor distance and upper-lip bite test were 65.12%, 53.49%, 18.6%, 30.23% and 72.09% respectively. Specificity of RHTMD, modified Mallampati test, sterno-mental distance, inter-incisor distance and upper-lip bite test was 90.51%, 90.34%, 97.22%, 98.20%, and 89.69% respectively. Area under the ROC curve was highest for RHTMD (0.881). Area under the ROC curve for modified Mallampati test, sterno-mental distance, inter-incisor distance and upper-lip bite test was 0.742, 0.621, 0.757 and 0.815 respectively. RHTMD had a sensitivity, specificity, and AUC for predicting difficult intubation of 66.67%, 87.60%, and 0.908 respectively. ConclusionWe primarily conclude that RHTMD has a good predictive performance and is similar to modified Mallampati test as a predictor of difficult visualization of larynx. We secondarily conclude that RHTMD is a better predictor of difficult visualization of larynx compared to sterno-mental distance, inter-incisor distance and upper-lip bite test. It is also an excellent predictor of IDS> 5.

ACROMIO-AXILLO-SUPRASTERNAL NOTCH INDEX [AASI] : A SCREENING METHOD TO PREDICT DIFFICULT LARYNGOSCOPY IN PATIENT UNDERGOING GENERAL ANAESTHESIA AND REQUIRING ENDOTRACHEAL INTUBATION

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.

Role of Acromioaxillosuprasternal Notch Index (AASI) as a New Predictor of Difficult Visualization of Larynx in Comparison with Modified Mallampati Test

Background: Pre-operative airway assessment should be able to predict potential difficult airway, allowing management plan to be developed ahead of time. Hence this study was aimed to compare Acromio-AxilloSuprasternal Notch Index (AASI), a new simple bedside test with Modified Mallampati Test (MMP) in predicting difficult visualization of larynx. Materials and Methods: After ethical committee clearance and informed written consent, 320 patients of ASA I and II posted for elective surgery under general anaesthesia were included in this study. AASI and MMP were noted during preanaesthetic airway assessment. After induction of anaesthesia, a blinded and experienced anaesthetist did laryngoscopy, intubated the patient and noted Cormack-Lehane(CL) grading of laryngeal view. The data observed was analysed using Receiver operating characteristic curve(ROC) analysis to compare AASI and MMP. A P value less than 0.05 was considered statistically significant. Results: Incidence of Difficult Visualization of Larynx(DVL) in our study was 8.4%. AASI had better Sensitivity(88.89% v/s 22.22%), Specificity(98.63% v/s 95.22%),Positive predictive value (85.71% v/s 26.32%), Negative predictive value (98.97% v/s 93%) and Diagnostic accuracy(97.81% v/s 89.03%) in comparison with MMP respectively (P <0.001) when cut off reference value of 0.56 AASI was taken. Conclusion: AASI is a better predictor of difficult laryngoscopy with a higher sensitivity and positive predictive value in comparison with MMP. Hence AASI can be used as a simple bedside test to predict difficult airway during pre-anaesthetic airway assessment. Keywords: Acromioaxillosuprasternal notch index (AASI); Modified Mallampati test (MMP); Cormack-Lehane (CL) grade; Difficult visualization of larynx (DVL); Airway assessment.

English

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

A comparative study of acromio-axillo-suprasternal notch index with upper lip bite test and modified Mallampati score to predict difficult laryngoscopy

Background: The current bedside predictors of the difficult airway are not perfect. A new test, the acromio-axillo-suprasternal notch index (AASI), has been found to be superior to conventional predictors. In this study, we have compared the accuracy of AASI with upper lip bite test (ULBT) and modified Mallampati (MMP) test to predict difficult laryngoscopy and the time taken to complete each test.Methods: Institutional ethical committee clearance was obtained, and written informed consent was taken from 150 patients posted for elective surgery under general anesthesia with endotracheal intubation. Preoperative airway examination was carried out with AASI, ULBT, and MMP score. AASI ≥0.49, ULBT Class III, and MMP score III/IV were considered as predictive of difficult visualization of larynx (DVL). After the induction of anesthesia, the laryngeal view was recorded according to Cormack–Lehane (CL) grade. Sensitivity, specificity, predictive values, and accuracy were calculated for all the three tests.Results: DVL (CL Grades 3/4) was observed in 18 (12%) patients. AASI was found to have higher specificity (93.2%), positive predictive value (PPV) (55%), and accuracy (89.3%) when compared to MMP and ULBT. MMP was found to have the highest sensitivity (77.8%), and ULBT was found to have least sensitivity (50%). Time taken for AASI was higher (13.01 ± 1.03 s) when compared to ULBT (7.49 ± 1.95 s) and MMP (3.97 ± 0.49 s).Conclusion: We conclude that the MMP is the most sensitive and fastest test to predict DVL when compared to AASI and ULBT. AASI is a better predictor for DVL as it has higher specificity, PPV, accuracy, and odds ratio when compared to standard tests such as MMP and ULBT.

Predictive validity of acromio-axillo-suprasternal notch index for assessing difficult laryngoscopic view

these tests either individually or in combination failed to predict difficult visualization of larynx reliably. So the quest for a new test continues. All patients were enrolled in the study after obtaining written consent. Study was conducted after obtaining permission from ethical committee of the hospital. It was a prospective, comparative, observational study. A sample size of 250 was calculated. Of the total 219 patients in EVL 20(9.1) were having AASI of >0.5 and 199(90.9) had AASI 0.5 and 10(32.3) had AASI

Comparision of acromio-axillo-suprasternal notch index with modified mallampati test and thyromental distance in predicting difficult visualisation of larynx-a prospective, comparative, observational study

Introduction: The incidence of tracheal intubation was reported to be in the range of 0.1-20.2%; this variation was due to the different patient populations and criteria used. Consequently, prediction of difficult intubation relies on various tests and their combinations. Yet, these tests either individually or in combination failed to predict difficult visualization of larynx reliably. So the quest for a new test continues. AASI, a relatively new test, based on surface land mark, has been suggested to reliably predict difficult visualization of larynx.Methodology: A total of 250 adult patients aged 18-60 years, belonging to ASA class 1 and 2 who were candidates undergoing elective surgery under general anaesthesia requiring tracheal intubation were enrolled in this study.Results: Out of 250 patients, 31 patients had DVL in which 21(67.7%) had AASI of >0.5 and 10(32.3%) had AASI of 0.5% and 199 patients had AASI of

The predictive value of the ratio of neck circumference to thyromental distance in comparison with four predictive tests for difficult laryngoscopy in obstetric patients scheduled for caesarean delivery.

Background:Preoperative assessment of anatomical landmarks andclinical factors help detect potentially difficult laryngoscopies. The aim of the present study was to compare the ability to predict difficult visualization of the larynx from thefollowing preoperative airway predictive indices, in isolation and combination: Neck circumference to thyromental distance (NC/TMD), neck circumference (NC), modified Mallampatitest (MMT), the ratio of height to thyromental distance (RHTMD), and the upper-lip-bite test (ULBT).Materials and Methods:We collected data on657 consecutive patients scheduled for elective caesarean delivery under general anesthesia requiring endotracheal intubation and then evaluated all five factors before caesarean. An experienced anesthesiologist, not informed of the recorded preoperative airway evaluation, performed the laryngoscopy and grading (as per Cormack and Lehane's classification). Sensitivity, specificity, and positive and negative predictive values for each airway predictor in isolation and in combination were determined.Results:Difficult laryngoscopy (Grade 3 or 4) occurred in 53 (8.06%) patients. There were significant differences in thyromental distance (TMD), RHTMD, NC, and NC/TMD between difficult visualization of larynx and easy visualization of larynx patients (P < 0.05). The main end-point area under curve (AUC) of the receiver-operating characteristic (ROC) was lower for MMT (AUC = 0.497; 95% Confidence Interval = CI,0.045-0.536) and ULBT (AUC = 0.500, 95% CI, 0.461-0.539) compared to RHTMD, NC, TMD, and NC/TMD score ([AUC = 0.627, 95% CI, 0.589-0.664], [AUC = 0.691; 95% CI, 0.654-0.726], [AUC = 0.606; 95% CI, 0.567-0.643], [AUC = 0.689;95% CI, 0.625-0.724], respectively), and the differences of six ROC curves were statistically significant (P < 0.05).Conclusion:The NC/TM Discomparable with NC, RHTMD, and ULBT for the prediction of difficult laryngoscopy in caes are an delivery.

Comparison of acromioaxillosuprasternal notch index (a new test) with modified Mallampati test in predicting difficult visualization of larynx

BackgroundWe aimed to compare the efficacy of a new bedside screening test named acromioaxillosuprasternal notch index (AASI) with modified Mallampati (MMP). MethodsA total of 603 adult patients, who were candidates for tracheal intubation in elective surgery, were enrolled in this prospective study. Preoperative airway assessment was carried out with AASI and MMP. The new AASI score is calculated based on the following measurements: (1) using a ruler, a vertical line is drawn from the top of the acromion process to the superior border of the axilla at the pectoralis major muscle (line A); (2) a second line is drawn perpendicular to line A from the suprasternal notch (line B); and (3) the portion of line A that lies above the point where line B intersects it is line C. AASI is calculated by dividing the length of line C by that of line A (AASI = C/A). After induction of anesthesia, the laryngeal view was recorded according to the Cormack–Lehane grading system. Receiver operating characteristic curve analysis was employed to compare between AASI and MMP. ResultsDifficult visualization of larynx (DVL, Cormack–Lehane III and IV) was observed in 38 (6.3%) patients. The best cutoff point for DVL was defined at AASI > 0.49. AASI had a lower false negative rate and higher predictive values (sensitivity, positive predictive value, and accuracy) in comparison with MMP. ConclusionAASI was associated with higher predictive values than MMP and could be used for estimation of DVL.

English

BACKGROUND: Unanticipated difficult tracheal intubation is a significant source of morbidity and mortality in anaesthetic practice which can be reduced by identification of potential difficult intubation. OBJECTIVE: We aimed the present study to know the incidence of difficult intubation, factors associated with it and the predictive value of various airway predictors in anticipating difficult visualization of larynx and difficult intubation. METHODS: 435 adult patients (>18 year) undergoing general anaesthesia with intubation were examined preoperatively for demographic details (age, sex, weight), dentition, airway pathology and six airway predictors i.e. Inter Incisor Gap (IIG), Modified Mallampatti Grading (MMPG), Upper lip bite test (ULBT), Thyromental distance (TMD), Sternomental distance (SMD) and subluxation of mandible (SLM). All patients were anaesthetized using standard protocol with thiopentone (5mg/kg) and succinylcholine (1.5 mg/kg). On direct laryngoscopy, Cormack Lehane (CL) grading was noted. CL grade I, II was defined as easy visualization of larynx (EVL) and CL grade III, IV as difficult visualization of larynx (DVL). Difficult intubation score (DIS) was calculated as sum of CL grade and number of intubation attempts. DIS of less than or equal to 4 was defined as easy intubation (EI) and DIS > 4 was defined as difficult intubation (DI).Sensitivity, specificity, positive and negative predictive value, positive and negative likelihood ratios(LR) and odd's ratio value for six airway predictor tests was calculated by standard formulae. RESULTS: Incidence of DVL was 12.65% (n=55) and DI was 9.65% (n=42), with no failed intubation. All airway tests had very high negative predictive value (>90%) which implicates they identify easy intubations more precisely. MMPG and ULBT were found as airway predictors for difficult intubation having odds ratio of 85.23 (95% CI 25.42- 285.89%) and 65.45 (95% CI 25.69-166.7%) respectively, along with very high sensitivity of 92.80% and 85.7% respectively. Presence of ULBT III is the best predictor of difficult intubation (+LR 21.97) and absence of MMPG III, IV is the best predictor of difficult intubation (-LR 0.091). Abnormal dentition and airway pathology also increase the risk of difficult intubation, P<0.001. CONCLUSION: We conclude that ULBT and MMPG are nearly perfect airway predictors and should be used routinely during pre-anesthetic visit for screening of difficult intubation.