Ultrasound vs. Clinical Assessment: Revolutionizing Predictions for Difficult Laryngoscopy, study finds

Recent study investigates the effectiveness of the El-Ganzouri risk index (EGRI) and skin-to-epiglottis distance (SED) as predictors of difficult laryngoscopy, which is a critical component of airway management in anesthesia. Conducted on 129 patients classified as American Society of Anesthesiologists (ASA) class I or II, aged between 25 and 70, the research focused on comparing these two assessment methods prior to tracheal intubation. Various preoperative assessments were performed, including EGRI, which incorporates factors such as mouth opening, thyromental distance, head and neck movements, obesity, and previous intubation difficulties. The study sought to correlate these preoperative findings with laryngoscopic views classified by the Cormack-Lehane (CL) grading system, which determines the visibility of the glottis during intubation. Results indicated that the EGRI exhibited a sensitivity of 88.9%, specificity of 6.7%, positive predictive value (PPV) of 33.3%, and negative predictive value (NPV) of 99%. In contrast, the SED demonstrated superior diagnostic performance with a sensitivity of 96%, specificity of 100%, PPV of 100%, and NPV of 99% when a threshold of 18 mm was applied. These findings underscore the utility of sonographically measured SED as a more reliable parameter for anticipating challenging intubations.

ROC Analysis

The study employed a receiver operating characteristic (ROC) analysis to evaluate the predictive capabilities of both EGRI and SED. The area under the ROC curve (AUC) for SED was significantly higher at 0.995, compared to 0.662 for EGRI, suggesting that SED measurements provide more accurate predictions of difficult laryngoscopy. Furthermore, a new cut-off for SED was proposed based on ROC analysis, setting the optimal threshold at 15 mm for enhanced predictive value, despite the study utilizing 18 mm as the operational cut-off.

Patient Assessment

During the assessment, patients were positioned appropriately to simulate the conditions of real intubation, and trained anesthesia personnel performed ultrasound measurements to determine SED at the level of the thyrohyoid membrane. The laryngoscopic evaluation revealed that 24 patients (18.6%) experienced difficult laryngoscopy, as classified under CL grades III and IV.

Methodology Comparison

The analysis also drew comparisons to existing airway assessment methods, accentuating the limitations of solely clinical parameters and the variability in their predictive performance due to confounding factors such as inter-observer differences. The superior accuracy of ultrasound-based measurements suggests a shift towards integrating sonographic techniques in routine preoperative airway assessments.

Conclusion and Future Directions

In conclusion, the findings establish that sonologically assessed SED surpasses EGRI in sensitivity and specificity for predicting difficult laryngoscopy, emphasizing its role as a critical adjunct to conventional clinical tests. The proposed combined scoring system, integrating SED and EGRI, aims to further refine the predictive ability regarding laryngoscopy difficulties, although further research with larger sample sizes is warranted to validate these results and the proposed scoring methodology. The study advocates for the adoption of SED in clinical practice to enhance preoperative airway management strategies.

Key Points -

\- \*\*Study Design and Population\*\*: The investigation involved 129 patients classified as ASA class I or II, aged 25 to 70. The focus was on comparing the effectiveness of the El-Ganzouri risk index (EGRI) and skin-to-epiglottis distance (SED) in predicting difficult laryngoscopy prior to tracheal intubation.

- \*\*Predictive Performance of EGRI and SED\*\*: Results indicated that EGRI had a sensitivity of 88.9%, specificity of 6.7%, a positive predictive value (PPV) of 33.3%, and a negative predictive value (NPV) of 99%. In contrast, SED demonstrated significantly higher performance with sensitivity of 96%, specificity of 100%, PPV of 100%, and NPV of 99%, especially when using a threshold of 18 mm.

- \*\*ROC Analysis Findings\*\*: Receiver operating characteristic (ROC) analysis showed that the area under the ROC curve (AUC) for SED was 0.995, indicating excellent predictive capability, while EGRI’s AUC was only 0.662. A new optimal cut-off for SED was suggested at 15 mm for enhanced predictive ability.

- \*\*Ultrasound Measurement Methodology\*\*: Patients were accurately positioned for real intubation scenarios, and trained anesthesia personnel utilized ultrasound to measure SED at the thyrohyoid membrane level. Difficult laryngoscopy (CL grades III and IV) was observed in 18.6% of the subjects during laryngoscopic evaluations.

- \*\*Limitations of Existing Assessments\*\*: The study highlighted limitations found in existing airway assessment methods, particularly emphasizing the inadequacies of relying solely on clinical parameters, which can be affected by inter-observer variability. Ultrasound-based measurements provide a more objective and reliable approach.

- \*\*Conclusion and Recommendations\*\*: Findings support that sonologically assessed SED is superior to EGRI for predicting difficult laryngoscopy and propose a combined scoring system incorporating both factors for improved accuracy. The study recommends the integration of SED into clinical practice for better preoperative airway management, while also calling for further research with larger samples to validate the results.

Reference –

Fareeda Karimbanakkal et al. (2025). Comparison Between El-Ganzouri Risk Index And Sonologically Measured Skin-To-Epiglottis Distance For Predicting Difficult Laryngoscopy: A Prospective Observational Study. *Indian Journal Of Anaesthesia*. https://doi.org/10.4103/ija.ija_896_24.