Novel Pulmonary Function Parameter Shifts in High-Grade Upper Airway Stenoses

Abstract

Upper airway stenosis (UAS) is a common problem for anesthesiologists in laryngology as well as head and neck surgery, but it may lead to life-threatening situations if it is undetected. This retrospective case series was performed on patients who had UAS and presented with severe dyspnea or encountered difficulties in airway management. To assess the severity of UAS, the degree of stenosis was calculated using computed tomography scans and direct endoscopy. Lung function test was collected, and measured values were extracted as percentage of predicted reference values. Lower and higher grade stenoses were defined by Cotton-Myer classification and median degree of stenosis. Median of detected stenoses was 73% (64%-85%), with 7 of 10 patients classified as Cotton-Myer grade 3. Lung function tests showed typical parameter shifts as known from obstructive pulmonary diseases (OPDs). Furthermore, statistical analyses showed a significant higher value of residual volume (RV)/total lung capacity (TLC) in patients with higher grade stenosis (P < .05), whereas forced expiratory volume in 1 second /vital capacity (FEV1/VC) did not show a significant difference in same subgroups. In conclusion, the elevation of RV/TLC with concomitant normal FEV1/VC in symptomatic patients could be used to demarcate rare UAS from common OPD. Moreover, RV-TLC ratio might be used to distinguish between low- and high-grade UAS. But further epidemiological studies will be necessary to validate these findings. Level of evidence: 4.