Prediction of Difficult Laryngoscopy by Ultrasound Guided Valuation of Anterior Neck Soft Tissue Thickness.

Abstract

Background : The major responsibility of the anaesthesiologist is to provide adequate ventilation to the patient. Most vital element for this is the airway. Difficulties in optimal airway management can lead to serious adverse effects and failure can even lead to mortality. We have evaluated the feasibility of sonography as an imaging tool in identifying important airway anatomical structures on the anterior aspect of the neck and correlated the ultrasound-guided measurements of the airway parameters with the Cormack Lehane classification of the direct laryngoscopy for prediction of the difficult airway. Aim : To predict Difficult Laryngoscopy by Ultrasound guided valuation Of Anterior Neck Soft Tissue Thickness. Method : The study was a prospective observational study. For this study, n (no of cases) =100 considering power of 95% from the previous study; including patients between the age group of 18 to 65 years, ASA I to III grades, scheduled for elective surgery and requiring general anaesthesia with directlaryngoscopy and endotracheal intubation. Patient with anticipated difficult airway were excluded. Modified Mallampati score, Neck circumference at the level of the thyroid cartilage, Thyromental distance, BMI, distance from skin to hyoid bone and distance from skin to the anterior commissure of vocal cords using the USG machine followed by MCLS grade on laryngoscopy were noted. Result : With reference to ROC analysis, the optimal cutoffs of DSHB, DSAC, neck circumference and BMI measurements for the prediction of difficult Laryngoscopy is 0.81 cm, 0.92 cm, 35.75cm and 24.8 kg/m 2 respectively with the area under the curves being 0.944, 0.970, 0.801 and 0.745 respectively. Similarly, the optimal cutoff value for modifiedMallampati grades for the prediction of difficult Laryngoscopy is Grade II and above with area under the curves being 0.718. We also found that with experience the required time to measure the distances using USG was reduced with experience. Conclusion : We conclude from our study that the BMI, modified Mallampati grade and neck circumference are good predictors of

Prediction of Difficult Laryngoscopy Using Ultrasound: A Systematic Review and Meta-Analysis

“…The risk of bias was judged as low with the use of the Cormack-Lehane classification and difficult intubation as the reference tests and also judged as low with the index ultrasound tests. The overall risk of bias in patient selection was judged as low in all but one study where it was unclear (6). The risk of bias was unclear in two studies in the domains of index test and reference test (6, 13); blinding status was not reported in both studies.…”

“…Authors have described several composite airway scoring systems for improving the identification of difficult intubation. These systems apply multiple assessments toward scoring risk for difficult intubation and include the Simplified Predictive Intubation Difficulty Score (6) and the Total Airway Score (7), among others. However, the performances of these composite measures are not appreciably better than physical examination, with sensitivities below 0.69 (6, 7).…”

Accuracy of Preoperative Ultrasonographic Airway Assessment in Predicting Difficult Laryngoscopies in Adult Patients

“…If a difficult airway is anticipated before induction of anesthesia, proper planning can be made regarding proper equipment and technique, and experienced anesthesiologists can be involved in managing the airway. Various methods can predict a difficult airway, but none of them are completely accurate [3].…”

“…With the advancement of technology in hospitals and the availability of portable USG machines, anesthesiologists can use USG as a clinical tool for assessing airways and ruling out difficult airways to prevent a scenario where ventilation and intubation are not possible [3].…”

“…Various anatomical parameters can be used to evaluate the ease of endotracheal intubation. However, their measurements are subjective, depending on the observer, and hence have less sensitivity and specificity [3].…”