Prospective Single Blinded Study Of Six Airway Assessment Tests Compared Individually With Cormack & Lehane Score In Predicting Difficult Intubation (original) (raw)
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Airway Assessment for Anticipation of Difficult Intubation: A Double Blind Comparative Study
Journal of Evolution of Medical and Dental Sciences
BACKGROUND AND AIMS In this era of high technology, we still face an ageless problem in anaesthesia-the difficult airway. In 1997, Smarajith Sur Roy of India introduced a new airway index to predict difficult intubation. Aim of the study is to compare the new airway index with modified Mallampati classification and also with Cormack and Lehane grading for predicting intubation difficulty. MATERIALS AND METHODS The study was conducted on 200 patients undergoing various surgeries at a Government Medical College Hospital. Patients between the age group of 15 to 50 years and belonging to American Society of Anaesthesiologist Grade 1 or 2 were selected. Patients were graded using Modified Mallampati classification. Then in hyperextended neck, the distance between the angle of mandible and the midpoint of Symphysis menti (Variable A) and the distance between the symphysis menti and the thyroid notch (Variable B) were taken in centimetres and A/B ratio calculated. This ratio is the New Airway Index. After premedication and induction of anaesthesia, laryngoscopy was done, Cormack and Lehane grade noted and intubation difficulty assessed. The predictive value of the new airway index was compared against modified Mallampati classification as well as Cormack and Lehane grading and statistical significance assessed. RESULTS The observations made on the calculation of the new airway index were, 1. When the airway index was 1, the intubation was very easy, irrespective of the findings of Mallampati classification and Cormack and Lehane Grade was 1; 2. When the index was 1 to 1.399, the intubation was easier and the laryngoscopic findings were of Cormack and Lehane Grade II; 3. When the index was 1.4 or more, the intubation was difficult and they belonged to Cormack and Lehane Grade III. The predictability was also statistically very significant when compared with modified Mallampati classification (p<0.001-Chi square test-test for single proportion). The success rate of the new airway index was also high when compared with Cormack and Lehane grading. CONCLUSION This study confirms the efficacy of the new airway index in predicting difficult intubation.
A Prospective Study to Predict difficult intubation using Simple Non-Invasive Tests
Introduction: Failure to achieve endotracheal intubation causes considerable morbidity and mortality in anaesthetised patients. Preoperative identification of such patients would help the Anesthesiologist to be prepared for such a difficult situation. The purpose of our study was to determine the ability to predict difficult visualization of larynx using the Upper Lip Bite Test (ULBT), Hyomental distance (HMD), Thyrosternal distance (TSD), and the Mandibular length (ML). Material and methods: Study group included 100 patients undergoing elective surgical procedures under general anaesthesia with endotracheal intubation. ULBT, HMD, TSD and ML measurements were performed on all patients preoperatively. ULBT class III, HMD <3.5cm, TSD < 6.5cm and ML< 9cm were considered potentially difficult intubation. An experienced anesthesiologist, unaware of preoperative airway evaluation, performed the laryngoscopy and graded the glottic view(as per Cormack and Lehane's (CL) classification). CL Grade III and IV were considered as difficult intubation. We calculated the Sensitivity, specificity, accuracy, positive and negative predictive values of upper lip bite test and Modified Mallampati test. Results: ULBT had a sensitivity, specificity, PPV and NPV of 45.45%, 100%, 100% and 93.68%, respectively. HMD showed a Sensitivity, Specificity, PPV and NPV of 9.09%, 97.75%, 33.33% and 89.69%, respectively. TSD showed a Sensitivity and PPV came of 0% while the Specificity and NPV of the test to be 97.75% and 88.78%, respectively. ML showed Sensitivity, Specificity, PPV and NPV and found of 18.18%, 98.88%, 66.67% and 90.72%, respectively. Conclusion. ULBT comes out to be a better predictor of Difficult Intubation over HMD, TSD and ML. Though, ULBT appears to be better amongst the four tests, none of them is a foolproof test. None of them can be used as a reliable screening test as no one had a sensitivity even more than 50%. But, ULBT is better predictor amongst above parameters.
COMPARISON OF PREDICTORS OF DIFFICULT INTUBATION
Context: Unanticipated difficult laryngoscopy and tracheal intubation always remain a primary concern for an anaesthesiologist as the failure to maintain a patent airway during induction of anaesthesia may lead to anaesthesia related morbidity and mortality. Aims: The aim of our study was to predict difficult intubation and to identify best predictor(s) among them and also to compare the sensitivity, specificity, positive predictive value, negative predictive value and accuracy of various airway parameters.Airway parameters taken in our study were Modified Mallampati Classification (MMT), Thyromental Distance (TMD), Sternomental Distance (SMD), Interincisor Gap (IIG), Upper Lip Bite Test (ULBT), Degree of Neck Extension (DNE), Anterior Subluxation of Mandible (ASM) and Protruding Teeth (PT). Methods and Material: 350 patients of ASA Grade 1 and 2 scheduled for various elective surgeries under general anaesthesia were included in our study and were assessed preoperatively for different airway parameters. Intraoperatively all patients were classified as difficult and easy intubation group according to Cormack and Lehane laryngoscopic view. Clinical data of each test was collected, tabulated and analyzed to obtain the sensitivity, specificity, positive predictive value and negative predictive value. Results: The upper lip bite test had the highest sensitivity (80%); Anterior subluxation of mandible had highest specificity (99.06%) and both of above were most accurate tests. The overall incidence of difficult intubation was 8.57%. Conclusion: Upper lip bite test was the best predictor of difficult intubation and it should be included as a routine test along with Modified mallampati test in preanaesthetic evaluation.
Airway assessment: Predictors for difficult intubation – A prospective observational study
Indian Journal of Clinical Anaesthesia
Airway management remains an important challenge in the contemporary practice of anaesthesia and preoperative airway assessment facilitates appropriate preparation when difficulty with intubation or ventilation is anticipated prior to induction of anaesthesia.: Aim: To study the important predictors for difficult laryngeal intubation. To determine the predictors of difficult laryngeal intubation. Secondary: To determine the most significant predictor for difficult intubation and to determine the incidence of unanticipated difficult intubation.This single centre prospective observational study done in Bangalore Baptist hospital (after obtaining clearance from ethical committee) included adult patients posted for elective surgeries who received general anaesthesia. Patients of either gender in the 18 – 65 year age group, with an American Society of Anaesthesiologists physical status classification of I or II, who required endotracheal intubation for general anaesthesia. The sample siz...
IP innovative publication pvt. ltd, 2019
Introduction: No anaesthesiologist like to face scenario of unanticipated difficult intubation, as it may cost patients life. Many tests are there to predict difficult intubation, amongst those tests Modified Mallampati test [MMT] is a gold standard test. Upper lip bite test [ULBT] is an acceptable option for predicting difficult intubation. Our study aimed to compare both the tests to predict difficult intubation. Objectives: To analyse positive predictive value (PPV), negative predictive value (NPV), sensitivity, specificity and accuracy of ULBT and MMT. To compare the results of both the tests to predict difficult intubation. Aim: To ascertain whether ULBT can be incorporated in standard protocol of airway assessment along with other tests to increase predictive accuracy of difficult endotracheal intubation Materials and Methods: It was prospective randomised comparative observational study carried out at single centre. Three hundred patients of either sex, aged between 16-60 yrs scheduled for elective surgery under general anaesthesia with endotracheal intubation were enrolled in the study. Preoperative evaluation of airway was done with ULBT and MMT and findings were documented.MMT class III,IV and ULBT class III were considered as predictors of difficult intubation. On the day of the surgery after direct laryngoscopy laryngeal view was noted and was classified according to Cormack and Lehane classification. Patients with Cormack Lehane class III,IV considered as difficult to intubate. Cormack Lehane classification (C &L class) redings were compared with ULBT and MMT. Observations and Results: Demographic data and ASA grade was same for both the groups as participants were same. By comparing ULBT with Cormack and Lehane score we got 88.46% sensitivity, 92.74% specificity, 71.87% Positive predictive value (PPV), 97.45% ne gative predictive value (NPV) and 92% accuracy. For MMT we go t 19.23% sensitivity, 91.93% specificity, 33.33% PPV, 84.44% NPV a nd 79.33% accuracy. Thus results showed accuracy, sensi tivity, PPV and NPV of ULBT were superior than MMT while specificity of both the tests was similar. Conclusion: With higher level of sensitivity, PPV, NPV and accuracy ULBT is a better choice for predicting difficult airway than that of MMT. ULBT should be incorporated in standard airway assessment protocol along with other tests.
A prospective observational study to predict difficult intubation using simple non-invasive tests
Introduction: Airway assessment is the first step in successful airway management. Several anatomical and functional maneuvers can be performed to estimate the difficulty of endotracheal intubation. We aimed to elucidate the role of upper lip bite test (ULBT), hyomental/thyrosternal (HMD/TSD) distances, the mandible length (ML) and their correlation in predicting difficulty intubation in relation to laryngoscopic view as per Cormack Lehane (CL) grading. Methods: After institutional approval informed consent obtained from160 consecutive patients aged between 20 to 60 years of ASA grading I and II scheduled for elective surgical procedures requiring tracheal intubation and meeting the inclusion criteria were enrolled in this study. Each patient was evaluated regarding ULBT, HMD, TSD, ML. Larngoscopy was assessed and findings were graded according to Cormack and Lehane's grading system. Results: The above study states the Negative Predictive Value (NPV) and Positive Predictive Value (PPV) of ULBT were found to be 86.7% and 94.5% respectively. Specificities of ULBT, HMD, TSD and ML were found to be 98.6%, 97.8%, 96.4% and 97.8% respectively. Diagnostic accuracy of ULBT, HMD, TSD, ML were found to be 93.8%, 88.1%, 84.4% and 91.3% respectively. Conclusion: It concludes that high specificity, NPV, PPV and Accuracy of ULBT as revealed in this study could be good rationale for its application in the prediction of difficulty or easiness in the intubation.
Predictive value of bedside tests for difficult intubations
OBJECTIVE: The aim of this study is to find the ideal test(s) for the prediction of difficult laryngoscopic intubation. PATIENTS AND METHODS: One hundred and twenty patients were selected at random for this prospective observational study. The patients’ preoperative exams include the assessment of Mallampati classification, thyromental, sternomental, interincisor distances and neck circumference. The laryngoscopy was evaluated with using the Cormack Lehane classification. The sensitivity, specificity, positive and negative predictive values and accuracy of tests, alone and in combination, were assessed. RESULTS: No statistically significant difference was found between the difficult and easy intubation cases. Sternomental distance showed the highest sensitivity (76%) and positive predictor value (54%). As the critical value of neck circumference was set to 35 cm and above, the sensitivity was 74% and positive predictive value, 53%. For the neck circumference and sternomental distance combination, which is determined to be the most reliable and accurate criteria, the sensitivity was 62% and positive predictive value, 42%. CONCLUSIONS: The findings suggest that the sternomental distance and neck circumference combination may be a more accurate predictor of difficult intubation
Preoperative Assessment of Risk Factors for Difficult Intubation
2008
Objective: To determine a clinically useful variable for predicting difficult tracheal intubation in patients with seemingly normal airways. Design & Duration: Quasi experimental study from September 2004 to March 2005. Setting: Department of Anaesthesiology, Civil Hospital, Karachi. Patients: A total of 150 patients requiring tracheal intubation for elective surgery. Methodology: An airway assessment test was conducted on each patient prior to general anaesthesia, with respect to mouth opening, thyromental distance, Oropharyngeal (Mallampati) classification, neck movement, length of mandibular ramus, ability to prognath and body mass index. After induction of anaesthesia, the laryngeal view during laryngoscopy was graded and then the ability to intubate was assessed. Results: Incidence of difficult intubation occurred in 4(2.6%) cases out of 150 patients. Airway test that were significant for predicting difficult tracheal intubation was inter-incisor distance of 3cms, Mallampati cl...
Indian Journal of Clinical Anaesthesia
Diagnostic accuracy of various difficult airway predictors in anticipating difficult intubation have been studied in literature. Aims: To identify the best combination of bedside difficult airway tests in anticipating difficult intubation. Settings and Design: In this study 200 patients between the ages18-70 years, of American Society of Anaesthesiologists grade I II, posted for elective surgeries under general anaesthesia with intubation were enrolled. Materials and Methods: Modified Mallampati Grade, Thyromental Distance, Upper Lip Bite Test were noted on airway examination. Intubation difficulty during general anaesthesia was assessed by observing Cormack Lehane Grade, number of intubation attempts, use of external laryngeal pressure, Gum elastic bougie. Statistical Analysis used: Airway parameters of 200 patients were analysed in SPSS 20 software for sensitivity, specificity, positive predictive values, negative predictive values in individual tests and in various combinations with each other. Results: Among 200 patients, incidence of difficult intubation was 7% (14 patients). Patients needing two or more attempts for intubation, gum elastic bougie, external laryngeal pressure were five, eight and 30 respectively. Modified Mallampati Grade had sensitivity 64.3%, specificity 79%. Upper lip bite test had sensitivity 71.4%, specificity 41.9%. Combination of Modified Mallampati Grade with Upper Lip Bite Test had sensitivity 64.3%, specificity 84.9%, positive predictive value 80.9% which were statistically significant. Conclusions: Modified Mallampati Grade, Upper Lip Bite test individually and as combination have better diagnostic value, compared to other airway parameters, in predicting difficult intubation.
Journal of Evidence Based Medicine and Healthcare, 2015
BACKGROUND: This study was carried out to evaluate usefulness of preoperative Mallampati & Wilson's score grading as a predictor for difficult laryngoscopy & intubation. AIMS: To determine the accuracy of the modified Mallampati test and Wilson score for predicting difficult tracheal intubation and correlation with Cormack Lehane grading. METHODS: This prospective randomized cross sectional Study carried out in 200 patients, posted for surgical procedure under GA with ETT intubation. Preoperative airway assessment using Mallampati grading (MPG) & Wilson score done. Conventional anesthesia technique followed. Cormack Lehane grading done at laryngoscopy & correlated with previous scores for each patient. RESULTS: A MPG of I/II was found in 140 patients (70%), while 60 patients (30%) were class III/IV. 138 patients (69%) had a Wilson score of 0/1, while 60(30%) had a score of 2/3 and 2 patients (1%) scored ≥4. One hundred & eighty patients (90%) were classified as Cormack-Lehane grade I/II, while 20 patients (10%) were considered grade III/IV. Of the 60 patients with a Wilson score of 2/3, 6 cases (10%) two attempts were required and in 2 cases (3.3%) in spite of more than two attempts intubation proved impossible with the conventional laryngoscope, articulated McCoy blade was used. Two patients with a Wilson score ≥4 were intubated with gum elastic bougie, using articulated McCoy blade. Overall, out of 200, in 6 patients (3%) two attempts of intubation was required and 4 patients (2%) intubation required the use of some kind of gadget other than conventional laryngoscope and more than 2 attempts. The correlation between the Cormack-Lehane classification and the number of endotracheal intubation attempts showed that of the 180 patients with I / II grade, 4 patients (1.3%) two attempts were required. Of the 20 patients classified as Cormack-Lehane III/IV, 4 cases (20%) intubation proved impossible with conventional technique. This correlation was statistically significant. DISCUSSION: The Wilson score can successfully predict the patients in whom laryngoscopy may prove difficult (Wilson 2/3) (p=0.01). This reflects the good sensitivity. CONCLUSIONS: Wilson score, despite being seldom used in clinical practice, is a highly sensitive predictor of a difficult airway, although its specificity is low.