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.

Anatomic Features of the Neck as Predictive Markers of Difficult Direct Laryngoscopy in Men and Women : A Prospective Study

Recognising a potential difficult airway at the time of preanaesthesia check-up,is very crucial. Several bedside screening tests have been used in clinical practice for predicting the difficult laryngoscopy/intubation. Aim: The study was undertaken to compare diagnostic value of Thyromental distance(TMD) and ratio of height to thyromental distance (RHTMD) in predicting a Cormack Lehane grade> or =3. Design: Prospective, comparative, observationl study Methods: 320 ASA 1 & 2 patients were subjected to pre-operative measurements of the thyromental distance (TMD)and ratio of height to thyromental distance (RHTMD) during the routine pre anaesthesia checkup. In the operating room, direct laryngoscopy performed with a Macintosh blade by an experienced anesthetist not aware of the pre-op measurements. Difficult laryngoscopy was defined as inadequate exposure of the glottis (Cormack-Lehane grade 3 or 4) under direct laryngoscopy with a blade of appropriate length, without any external pressure or other manoeuvre applied. The preoperative data of TMD & RHTMD and the laryngoscopic findings are correlated to evaluate the sensitivity, specificity,Positive predictive value, & Negative predictive value of each test according to standard formulae. Results: RHTMD had a better sensitivity(65.3% vs 59.2% for TMD) as well as a better specificity (50.6% vs 45.8 for TMD) and positive and negative predictive values. Conclusion: Among the tests studied, ratio of height to thyromental distance proved to be more accurate test for predicting difficulty larngoscopy.

Evaluation of Modified Mallampati Score with Neck Circumference and Thyromental Distance to Predict Difficult Intubation in Non-obese Patients

Introduction: Preoperative diagnostic validity of airwayassessment help for prediction of difficult airway. Severalmodels were established for prediction of difficult intubation.In this study, we aim to predict difficult intubation in nonobese patients from various airway predictive indices suchas modified mallampati grade, neck movement (NM), neckcircumference (NC), thyrometal distance (TM), NC/TMD.Material and Methods: Total 121 patients with 18-72 yearsof age, ASA grade I or II, scheduled for elective surgerythat required general anaesthesia. Difficulty of intubationwas assessed using the IDS for each non-obese patient. Thestudy population was divided into two groups Easy (IDS <5)and Difficult intubation (IDS ≥5). Preoperative assessmentsincluded Mouth Opening (MO), modified mallampati grade,neck movement (NM), neck circumference (NC), thyrometaldistance (TM), NC/TMD. Multivariate analysis was usedto predict independent risk factors. Receiver OperatingCharacteristic Curve analysis (ROC analysis) was performedfor the airway assessment tests. The area under curve (AUC)was calculated.Results: The weight (59.74±7.76 kg and 65.00±5.92 kg)and BMI (21.51±1.79 and 23.8157±1.09) were significantlydifferent in between easy and difficult intubation. TheMouth Opening, NC, TMD, and NC/TMD were significantlyindependent risk factor for difficult intubation. NC/TMDwas showed higher sensitivity, specificity, positive predictivevalue (PPV) and a negative predictive value (NPV) with thirdlarge area under the curve (AUC) on the ROC curve.Conclusions: This study shows that the NC/TMD ratio canbe considered as a better predictor of difficult intubation innon-obese patients.

Comparison of predictive capability of different methods for difficult laryngoscopy / 临床麻醉学杂志

Objective To explore the predictive capability of different methods for difficult la-ryngoscopy and analyze its optimal cutoff value.Methods Three hundred consecutive patients (aged 18-65 years,weighing 42-88 kg,ASA physical status Ⅰ or Ⅱ)scheduled to undergo general anesthe-sia and surgery were invited to participate.Difficult airway assessments were performed by thyromen-tal height (TMH),thyromental distance (TMD),sternomental distance (SMD),modified Mallam-pati test (MMT)and ratio of height and TMD (RHTMD)before anesthetic induction.Cormack-Le-hane (C-L)grade of laryngoscopy view was assessed after induction.Sensitivity,specificity,positive predictive value (PPV),negative predictive value (NPV)and accuracy of these tests were calculated. Receiver operator characteristic (ROC)curve of TMH was performed to determine the optimal cutoff value of TMH.Results There were 22 patients diagnosed as difficult airway.Sensitivity,specificity, PPV,NPV and accuracy of TMH were higher than those of TMD,SMD and MMT tests.Sensitivity of RHTMD was lower than that of TMH test,and specificity,PPV,NPV and accuracy of RHTMD were similar to that of TMH.The optimal cutoff value of TMH was 4.9 cm through ROC curve. Conclusion The optimal cutoff value of TMH detecting difficult laryngoscopy was 4.9 cm.Similar to RHTMD,TMH appears to be more effective for prediction of difficult laryngoscopy than TMD, SMD and MMT.

Comparison and evaluation of various bedside tests to predict difficult endotracheal intubation.

Introduction: As difficult laryngoscopy is a multifactorial problem, therefore any preoperative assessment of difficult tracheal intubation should have high sensitivity and specificity and result in minimal false positive and false negative values. This study was conducted in an attempt to devise a method of predicting difficult intubation and to assess the reliability of six simple bedside tests to predict difficult intubation. Material and Methods: This double blind prospective study involved 100 adult patients posted for elective surgery under general anesthesia. The airways were assessed for modified Mallampati test, Thyromental Distance, Sternomental Distance, Inter incisor gap; Atlanto-Occipital joint extension and Upper Lip bite Test. The laryngoscopic view and difficulty of intubation were noted. The sensitivity, specificity, positive and negative predictive values were calculated. Results: No method either individual or in combination with others had 100% sensitivity. The Modified Mallampati test had 76% sensitivity. Upper Lip bite Test had 98.66% specificity. The combination of Modified Mallampati test and Inter incisor gap had 52% sensitivity and 86.66% specificity. Conclusion: The “composite intubation difficulty score” is an easy and reliable method of predicting difficult intubation.

Modified Mallampati Test, Thyromental Distance and Hyomental Distance for Accurately Predicting Difficult Visualization of the Larynx.

Background: This study has been done to compare Hyomental distance with the modified Mallampati test, Thyromental distance for accurately predicting difficult visualization of the larynx in apparently normal patients’. Methods: 198 apparently normal patients of > 18 years of age, with ASA 1 and 2, undergoing general anaesthesia with tracheal intubation were evaluated. A hard-plastic bond ruler is used to measure the distance. After induction and paralysis using glottic visualisation was assessed by using modified Cormach and Lehane classification with no external laryngeal manipulation. Results: The highest sensitivity of 44.44 % was observed in predicting difficult visualization of the larynx with modified Mallampati followed by TMD 11.11 % and HMD 11.11 % (2/18). Conclusion: An optimal combination of tests that includes the HMD,MMT,TMD and other predictors and performing the tests in combination for predicting Difficult Laryngoscopy, rather than using it alone.

The predictive value of five factors to the maternal difficulty airway / 实用医学杂志

Objective To research the most commonly used five method to evaluated the difficulty airway , and compare which methods were more suited for the pregnant woman in general anesthesia. Methods 214 patients with full-term pregnancy who requested emergency or elective caesarean-section were assigned. During the pre-anesthetic visit,we evaluated patients from Mallampati score, thyromental distance, body mass index (BMI), inter-incisor gap, and upper lip bite test. After endotracheal intubation ,patients were divided into 2 groups based on Cormack classification. Results Five ways sensitivity descending order were upper lip bite test (79.5%)、Mallampati score (76.9%)、BMI (56.4%)、inter-incisor gap (51.3%)、thyromental distance (35.9%); specificity descending order were upper lip bite test (93.1%)、Mallampati scores (86.3%)、inter-incisor gap (85.1%)、thyromental distance (76.6%)、BMI (62.3%). Conclusions In pregnant women ,Mallampati score and the upper lip bite test are the better indicators to predict difficult airway.

Difficult Intubation due to Low Located and Right Deviated Thyroid Cartilage: A case report / 대한마취과학회지

We report a case of difficult intubation due to a low located thyroid cartilage and a left deviated glottis abnormality. A 35-year-old woman was scheduled to undergo a laminectomy and discectomy for a L4-5 disc herniation. After injecting intravenous induction agents and muscle relaxant, intubation was attempted with a direct laryngoscope. However, no vocal cords were seen and only the epiglottis was seen albeit only slightly. According to Cormack and Lehane's grading, the patient was grade III. Although intubation was re-attempted after changing the anesthesiologist and device such as a light wand, the endotracheal tube could not be advanced below the epiglottis because of resistance. When patient was rechecked, her thyroid cartilage was located abnormally low and the thyromental distance was 14.5 cm. In addition, the preoperative chest X-ray revealed her airway to be deviated to the left. Intubation could be successfully performed after additional 100% oxygen mask ventilation. An otolaryngologic examination revealed that the glottic opening was deviated to the left, and ventricle of the larynx, which is normally not seen with a laryngocope was located to the center. It is believed that the reason for resistance of the advancing endotracheal tube was a centrally located ventricle of the larynx.

Comparative Study of Light Wand and Direct Laryngoscope: Correlation of Time to Intubation and Thyromental Distance, and Change of Blood Pressure and Heart Rate after Intubation / 대한마취과학회지

BACKGROUND: Direct laryngoscope may be less useful under conditions of limited visualization. Light wand is a lighted stylet to transilluminate neck tissues allowing intubation without visualization. Thus, difficult intubation due to anatomy can be overcome. For comparison of light wand and direct laryngoscope, we checked time to intubation (TTI), success rate, relation of TTI and thyromental distance (TMD), and change of blood pressure and heart rate after intubation. METHODS: We selected and randomly allocated sixty adults to direct layngoscope group (D) and light wand group (L). Without premedication, propofol and vecuronium were injected for intubation. Time to intubation was measured from the time of grasping direct laryngoscope or light wand until the time of inserting endotracheal tube into trachea. We checked the change of blood pressure and heart rate after intubation, and studied the correlation of TTI and TMD. RESULTS: TTI was 16.5 sec (6.53~115.3 sec) for group D and 11.8 sec (4.31~36.0 sec) for group L. There was no significant difference between the groups. The rise of blood pressure and heart rate was less with light wand. There was a correlation of [TTI]=1248- 388[TMD]-30[TMD]2 in group L patients whose TMD is less than 7 cm. CONCLUSION: Compared with direct laryngoscope, light wand is as easy to use and can be more effective especially for patients whose anatomy may make intubation difficult or whose cardiovascular system is unstable.

Comparative Study of Light Wand and Direct Laryngoscope: Correlation of Time to Intubation and Thyromental Distance, and Change of Blood Pressure and Heart Rate after Intubation / 대한마취과학회지

BACKGROUND: Direct laryngoscope may be less useful under conditions of limited visualization. Light wand is a lighted stylet to transilluminate neck tissues allowing intubation without visualization. Thus, difficult intubation due to anatomy can be overcome. For comparison of light wand and direct laryngoscope, we checked time to intubation (TTI), success rate, relation of TTI and thyromental distance (TMD), and change of blood pressure and heart rate after intubation. METHODS: We selected and randomly allocated sixty adults to direct layngoscope group (D) and light wand group (L). Without premedication, propofol and vecuronium were injected for intubation. Time to intubation was measured from the time of grasping direct laryngoscope or light wand until the time of inserting endotracheal tube into trachea. We checked the change of blood pressure and heart rate after intubation, and studied the correlation of TTI and TMD. RESULTS: TTI was 16.5 sec (6.53~115.3 sec) for group D and 11.8 sec (4.31~36.0 sec) for group L. There was no significant difference between the groups. The rise of blood pressure and heart rate was less with light wand. There was a correlation of [TTI]=1248- 388[TMD]-30[TMD]2 in group L patients whose TMD is less than 7 cm. CONCLUSION: Compared with direct laryngoscope, light wand is as easy to use and can be more effective especially for patients whose anatomy may make intubation difficult or whose cardiovascular system is unstable.