Comparative Analysis of a Preoperative Airway Ultrasound Protocol and Direct Laryngoscopy in Oncologic Surgery Patients

Overview

This prospective observational study evaluated the predictive performance of the Difficult Airway Evaluation with Sonography (DARES) protocol for identifying difficult laryngoscopy and other airway management difficulties in adult patients undergoing elective oncologic surgery. Preoperative airway ultrasonography was performed together with conventional clinical airway assessment. Ultrasound parameters included the distance from skin to epiglottis (DSE), hyomental distance (HMD) measured in different head positions, hyomental distance ratios (HMDR1 and HMDR2), and tongue thickness (TT). Conventional airway assessment parameters were also recorded. The primary objective was to evaluate the ability of ultrasound-derived airway parameters to predict difficult laryngoscopy, defined as a Cormack-Lehane grade \>2a (grades 2b, 3, or 4) during direct laryngoscopy, and to compare their predictive performance with conventional clinical airway assessment methods. Secondary objectives included evaluating the relationship between ultrasound parameters and difficult mask ventilation, assessed using the Han scale; investigating their relationship with difficulties or complications encountered during extubation; and exploring differences in airway ultrasound parameters and their predictive performance across oncologic patient subgroups.

This prospective observational cohort study evaluated the predictive performance of the previously described Difficult Airway Evaluation with Sonography (DARES) protocol in adult patients undergoing elective oncologic surgery. The study was conducted at the Department of Anesthesiology and Reanimation, Dr. Abdurrahman Yurtaslan Oncology Training and Research Hospital. A total of 118 participants were enrolled. All participants underwent preoperative airway assessment and perioperative airway management according to routine clinical practice. The DARES protocol incorporates selected sonographic parameters used for difficult airway assessment. Preoperative airway ultrasonography was performed in the premedication unit using a Mindray® ultrasound system. Sonographic measurements included skin-to-epiglottis distance (DSE), hyomental distance (HMD) measured in different head positions, hyomental distance ratios (HMDR1 and HMDR2), and tongue thickness (TT). DSE was measured using a 5-14 MHz linear probe, while HMD and TT were measured using a 4-10 MHz curvilinear probe. Ultrasound examinations were performed by a single trained investigator to minimize interobserver variability. In addition to the ultrasonographic measurements, conventional clinical airway assessment parameters were recorded. Mallampati classification was assessed preoperatively. Mask ventilation difficulty was evaluated using the Han scale, and laryngoscopic view was assessed using the Cormack-Lehane grading system during direct laryngoscopy. Difficult laryngoscopy was defined as a Cormack-Lehane grade \>2a (grades 2b, 3, or 4). Difficulties and complications encountered during extubation were also prospectively recorded. For patient safety, the results of the preoperative ultrasonographic airway assessment were made available to the anesthesiologist responsible for airway management, allowing appropriate precautions to be taken when difficult airway management was anticipated. Therefore, the anesthesiologist performing airway management was not blinded to the ultrasound findings. To reduce measurement-related observer variability, preoperative ultrasound measurements and intraoperative airway assessments were performed and recorded by different individuals. The primary objective was to evaluate the predictive performance of ultrasound-derived airway parameters for difficult laryngoscopy and to compare their performance with conventional clinical airway assessment. Secondary evaluations included the relationship between sonographic airway parameters and mask ventilation difficulty, difficulties or complications encountered during extubation, and exploratory analyses according to oncologic tumor type. Collected data included age, sex, body mass index, comorbidities, oncologic history, previous surgery and radiotherapy, Mallampati classification, previous anesthesia history, American Society of Anesthesiologists (ASA) physical status, Cormack-Lehane grade, Han mask ventilation grade, anesthesia type and duration, difficulties encountered during mask ventilation, and difficulties or complications encountered during extubation. Data were recorded using a dedicated case report form together with standard anesthesia records. Statistical analyses were performed using IBM SPSS Statistics version 25.0. The distribution of continuous variables was assessed using the Shapiro-Wilk or Kolmogorov-Smirnov test, as appropriate, and homogeneity of variances was assessed using Levene's test. Continuous variables were summarized using appropriate descriptive statistics according to their distribution, while categorical variables were presented as frequencies and percentages. Comparisons between two independent groups were performed using the independent-samples t-test or Mann-Whitney U test, as appropriate. Comparisons involving more than two groups were performed using one-way analysis of variance (ANOVA) or the Kruskal-Wallis test. Categorical variables were compared using the Pearson chi-square test or Fisher's exact test, as appropriate. The discriminatory performance of sonographic airway parameters, including DSE, HMD, HMDR1, HMDR2, and TT, was evaluated using receiver operating characteristic (ROC) curve analysis. Areas under the ROC curve (AUCs) were calculated, and optimal cutoff values were determined using the Youden Index. Diagnostic performance measures, including sensitivity, specificity, positive predictive value, and negative predictive value, were calculated where appropriate. Associations between continuous variables were evaluated using appropriate correlation analyses. A two-sided p value \<0.05 was considered statistically significant. No study-specific therapeutic intervention was performed, and participation did not require deviation from routine perioperative airway management.