Acromio-Axillo-Suprasternal Notch Index: A New Screening Test to Predict Difficult Laryngoscopy in General Population

Abstract

Background: Airway management expertness is essential in every medical specialty. Inability to manage Difficult Visualization of Larynx (DVL) can be life threatening. This trail was performed to assess the ability of a new index-Acromio-axillo-suprasternal notch index-to predict difficult laryngoscopy in normal population in comparison with the other common predictors. Materials and Methods: 728 consecutive patients with ASA class I & II candidate for general anesthesia with endotracheal intubation were enrolled to this study. The four usual tests MMT, ULBT, RHTMD, NC/TMD were assessed before induction of anesthesia. The new AASI test 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 pectoralis major 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 anesthesiologist who blinded to the assessment, the laryngoscopy was done and based on Cormack-Lehane classification, garding of laryngoscopy was recorded. Sensitivity, specificity, positive predictive value and AUC or ROC for each airway predictor in isolation and comparison with each other was established. Results: The sensitivity of AASI was 66.67% with AUC = 0.790(P = 0.000). But MMT as an old predictive test with NC/TMD and RHTMD with AUC or ROC curve 0.626, 0.531, 0.537 respectively, are not good predictors in this study (P > 0.05). But ULBT with sensitivity 52.38% can be a good predictor (P = 0.003). There are stepwise increases in the incidence of Cormack-Lehane grade III and IV as AASI was greater than 0.6. Conclusion: We considered the value of preoperative assessment of AASI ≥ 0.6 to be a good and reliable predictor for difficult visualization of larynx

An observational prospective study of performance of acromioaxillosuprasternal notch index in predicting difficult visualisation of the larynx

“…Published manuscripts do not provide enough information to understand the rationale of the cut-off values used. [ 2 3 4 ] On the basis of best possible trade-off between the cumulative rates of false and true positive cases [ Table 4 ], we also suggest a cut-off value of ≥0.5 for AASI.…”

“…Our finding concurs with the previous research findings on AASI. [ 2 3 4 ] Even though one study used a cut-off point of 0.5 for AASI, a cut-off of 0.6 was used in other studies. Published manuscripts do not provide enough information to understand the rationale of the cut-off values used.…”

“…Sensitivity and specificity of AASI vary across different studies. [ 2 3 4 ] Among other factors, sensitivity and specificity depend on the prevalence of the condition under evaluation. [ 12 ] The prevalence of DVL in studies evaluating AASI in non-obstetric population are 2.9 and 6.3%.…”

“…[ 2 ] Studies that evaluated AASI have been carried out in populations from Iran only. [ 2 3 4 ] Cephalometric studies suggest that there are definite differences of anatomy between Asian and Western population that influences airway characteristics. [ 5 ] The hypothesis for this study was that AASI more than 0.5 will predict DVL.…”

Perbandingan Acromio Axillo Suprasternal Notch Index dengan Tes Mallampati dalam Prediksi Sulit Intubasi di RSUP Haji Adam Malik Medan

“…11 juga melakukan penelitian yang membandingkan AASI dengan prediktor lainnya terhadap sulit intubasi, ternyata AASI memiliki ROC yang lebih tinggi signifikan dibanding dengan tes lainnya sehingga lebih baik dalam memprediksi sulit intubasi daripada mallampati. 11,12 Subjek dan Metode…”