gms | German Medical Science

In the clinical routine glottic patency is estimated mainly by indirect laryngoscopy and self assessment of the patient. If there are discrepancies between laryngoscopic estimates and subjective complaints an objective measurement would be desirable.

In the present work two different methods for video analysis (glottic angle measurement and a relative glottic area index by Harnisch) were compared with a laser sizing system (Techno Pack II by Karl Storz, Tuttlingen, Germany) (Figure 1 [Fig. 1] ). 28 porcine larynx specimens were analysed in five different vocal fold positions. Image acquisition was realised with the fiberoptic camera system of the Techno Pack II. Measurements were analysed and correlated. Image resolution and barrel distortion limited accuracy in this controlled model. In a clinical setting this could be improved with rigid optics endoscopy.

We found very good correlations between laser sizing, glottic angle and glottic area index within the same specimen and looking at all measurements taken together (r>0.98). Separating results for different glottic widths revealed best correlations between laser sizing and glottic angle. Correlation was better for the clinically more relevant smaller glottic gaps (r=0.88) and decreased with increasing glottic gap (r=0.5). There were poor correlations between laser sizing and glottic area index (r=0.6 to r=0.1). In conclusion the glottic angle seems to be a simple and more robust parameter. It can be extrapolated in cases of an incomplete capture of the glottic gap.