Point-of-care ultrasound of the upper airway in difficult airway management: a systematic review and meta-analysis.

Summary

Across 60 studies (10,580 patients), upper airway point-of-care ultrasound parameters showed strong diagnostic accuracy for predicting difficult laryngoscopy (skin-to-vocal cords distance: sensitivity 0.84, specificity 0.81; AUROC 0.87) and difficult intubation (skin-to-epiglottis distance: sensitivity 0.80, specificity 0.86). Ultrasound guidance also improved first-pass success for percutaneous tracheostomy and cricothyroid membrane identification.

Key Findings

• Skin-to-vocal cords distance predicted difficult laryngoscopy with sensitivity 0.84, specificity 0.81, AUROC 0.87.
• Skin-to-epiglottis distance predicted difficult intubation with sensitivity 0.80 and specificity 0.86; skin-to-hyoid had AUROC 0.86.
• Ultrasound guidance increased first-pass success in percutaneous tracheostomy (OR ~3.9) and improved cricothyroid membrane identification (OR ~3.61) versus palpation.

Clinical Implications

Incorporate standardized airway ultrasound measurements (e.g., skin-to-vocal cord and skin-to-epiglottis distances) into difficult airway assessment and use ultrasound to guide cricothyroid membrane localization and percutaneous tracheostomy.

Limitations

• Heterogeneity across studies and parameters; not all analyses were high-certainty
• Diagnostic thresholds and scanning protocols may vary, limiting standardization

Future Directions

Prospective multicenter studies integrating airway ultrasound with clinical predictors to derive standardized cutoffs and algorithms, especially in high-risk populations.