Clinical predictors of difficult airway and their association with difficult orotracheal intubation in overweight and obese patients

Abstract

Introduction: Preoperative identification of a difficult airway is a critical component of patient safety during general anesthesia. Several bedside clinical tests have been proposed as predictive tools; however, their diagnostic accuracy when used individually remains limited, particularly in overweight and obese patients. Objective: To determine the correlation between clinical predictors of difficult airway and the occurrence of difficult orotracheal intubation in 83 adult patients with body mass index (BMI) 25 kg/m². Materials and Methods: An analytical observational cross-sectional study was conducted at the National Hospital of Itauguá, Paraguay, between 2023 and 2024. Eighty-three adult patients undergoing surgery under general anesthesia with orotracheal intubation were included through consecutive sampling. The following predictors of difficult airway were evaluated: Mallampati classification, thyromental distance (Patil-Aldreti test), mouth opening, neck circumference, and the Bellhouse-Doré scale. Intubation difficulty was assessed using the Cormack-Lehane classification during direct laryngoscopy. Difficult intubation was defined as Cormack-Lehane grades III–IV or the requirement of more than one intubation attempt. Correlation coefficients, sensitivity, specificity, positive predictive value, and negative predictive value were calculated. Statistical analyses were performed using IBM SPSS version 26.0. Results: The incidence of difficult intubation was 14.4%. The strongest correlation with difficult intubation was observed for the Cormack-Lehane classification (r=0.69), followed by Bellhouse-Doré (r=0.382), Patil-Aldreti (r=0.375), mouth opening (r=0.283), and Mallampati (r=0.25). Neck circumference showed minimal correlation (r=0.079). The Cormack-Lehane classification demonstrated the highest sensitivity (100%) and specificity (94%). The most frequent complication was esophageal intubation (6%). Discussion: No single clinical predictor demonstrated sufficient diagnostic accuracy to reliably identify difficult airway. The combined assessment of multiple clinical parameters improves predictive performance and contributes to safer airway management.