The diagnosis of subglottic stenosis (SGS) is usually made by clinical assessment and definitively by a direct endoscopic examination. This study aimed to evaluate different spirometric values in relation to anatomical grading and severity of subglottic stenosis cases of upper airway obstruction. Cases of SGS that underwent dilatational procedures endoscopically at the otolaryngology department of the King Saud University Medical City, Riyadh, Saudi Arabia, from June 2015 to October 2017 were collected. Pulmonary function test (PFT) pre-and postoperative parameters and the grades of subglottic stenosis were extracted. We compared different spirometric values to the severity of SGS and compared the pre-and postoperative results for each patient. There were 19 cases with a valid PFT study within 7 days preoperatively in addition to a documented intraoperative grading according to the Myer-Cotton grading system; 7 (36.8%) were grade 1, 8 (42.1%) were grade 2, and 4 (21.1%) were grade 3. The actual preoperative ratio of forced expiratory volume (FEV 1 ) in 1 second to peak expiratory flow (PEF) for all 19 patients ranged from 7.34 to 21.40 mL/L/min. We found a significant improvement in all spirometric parameters postdilatation including PEF (P < .001), FEV 1 (P < .001), FEV 1 /PEF (P ¼ .001), forced expiratory flow (FEF) from 25%, 50%, and 75% of vital capacity, respectively, FEF 25 (P < .001), FEF 50 (P ¼ .001), FEF 75 (P ¼ .048), and maximum mid-expiratory flow (P ¼ .002). We did not find any correlation between the severity of stenosis and spirometric values. This study revealed that spirometry is a useful marker in following up patients with subglottic stenosis and is also a good indicator to determine postairway surgery outcomes. However, these markers do not correlate with anatomical grading and the severity of subglottic stenosis.

Objectives: We aimed to comprehensively investigate different upper airway segments in adults, determine the predictors of the size of each segment, and identify an appropriate endotracheal tube (ETT) size chart. Study Design: Retrospective chart review. Setting: Tertiary care center. Materials and Methods: The data for patients aged >18 years who underwent neck computed tomography were screened. Patients with existing tumors, trauma, or any pathology that can alter the normal airway anatomy and those with intubation, tracheostomy, or nasogastric tubes were excluded. Computed tomography software was used to measure the anteroposterior diameter (APD), transverse diameter (TD), and cross-sectional area (CSA) at the glottic, proximal subglottic, distal subglottic, and tracheal levels. Multiple regression analysis was used to identify the predictors of the airway size. Results: One hundred patients were reviewed. The TD was consistently smaller than or equal to the APD at each level in all but 3 patients. The mean CSA and TD (170 mm2 and 11.3 mm, respectively) of the glottis indicated that the glottis was most often the narrowest level, followed by the proximal subglottis where the mean CSA and TD were 192.1 mm2 and 12.7 mm, respectively. Moreover, the mean APD was the smallest at the level of the trachea (20.1 mm). Multiple regression analysis confirmed that height and sex were the predominant predictors of measurements for the 4 airway segments. In addition, age was associated with the TD and CSA of the distal subglottic and tracheal segments, respectively. Conclusion: One-third of our participants exhibited a proximal subglottic diameter that was equal to or smaller than the glottic diameter. Our findings also suggested that the height and sex of the patients are important variables for the selection of an appropriate ETT size.

ObjectivesThis study aimed to compare the results of a software calculation method (SCM) and the mathematical calculation method (MCM) in measuring the cross-sectional area (CSA) at four different upper airway segments.MethodsThe data from the retrospective chart reviews of patients older than 18 years who had undergone computed tomography (CT) of the neck at our tertiary care center between September 2014 and September 2018 were reviewed. Data of patients who were intubated, tracheostomized, had nasogastric tubes, tumors, craniofacial anomalies, trauma, or any pathology that may affect the normal airway anatomy were excluded. We measured the anteroposterior (APD) and transverse diameter (TD) utilizing the CT software. CSA was calculated using both the mathematical formula (MCM) and software (SCM) at the glottis, proximal subglottis, distal subglottis, and tracheal levels. A paired sample t-test was used to determine the significant difference between SCM and MCM at each level.ResultsThe data of 100 patients (59% female) were reviewed. There was a significant difference between the SCM and MCM at all four levels. The mean differences between the SCM and MCM were -33.63 mm2, -24.20 mm2, 6.04 mm2 (p < 0.001) at the glottis, proximal subglottis, and trachea, respectively. The mean difference at the distal subglottis was -4.08 mm2 (p = 0.01).ConclusionOur study found a significant difference between the SCM and MCM in measuring the CSA of the four airway segments. Theoretically, the SCM is more accurate and precise than MCM in measuring CSA; however, we could not prove the superiority of either method.