Characterizing the Impact of Light Settings on Whiteout Frames during Flexible Endoscopic Evaluation of Swallowing

This study sought to assess whether an endoscope's light setting influenced the number of flexible endoscopic evaluation of swallowing (FEES) whiteout or pinkout frames in healthy subjects. We hypothesized that the number of whiteout frames during swallows from healthy participants would differ depending on the manual or automatic light setting.

Data were collected to assess the effect of Olympus endoscope light settings during FEES from healthy participants. Following a protocol of standard boluses, the light source was alternated between automatic and manual settings. During each swallow, purely white frames ("whiteout") and other hue frames ("pinkout") were counted for each bolus and light setting. A linear mixed-effects model was used to compare automatic and manual light settings while accounting for repeated swallows within participants and adjusting for bolus type.

Retrospective FEES videos from 8 healthy volunteers were used, and 117 swallows were analyzed. In descriptive analyses, the mean number of pure whiteout frames per swallow was 1.50 frames in the automatic setting and 13.97 frames in the manual setting. In the mixed-effects model, pure whiteout frame count was significantly lower in the automatic setting than in the manual setting (adjusted mean scores: 1.45 vs. 13.76 frames; p < 0.001). Pinkout frame count showed the opposite pattern and was significantly higher in the automatic setting than in the manual setting (adjusted mean scores: 14.42 vs. 3.26 frames; p < 0.001). When whiteout and pinkout frames were combined, there was no significant difference between automatic and manual light settings (adjusted mean scores: 16.17 vs. 16.84 frames; p = 0.681). A greater proportion of combined whiteout + pinkout frame counts fell within the expected normative whiteout-duration range under the automatic versus manual light setting (84.8% vs. 81.7%, respectively).

These preliminary findings suggest that endoscopic light settings may influence the appearance and measured frame counts of whiteout and pinkout during FEES. Automatic and manual light settings produced different patterns of pure whiteout and pinkout frames, while combined whiteout + pinkout frame counts were more similar across settings. These findings support the importance of documenting and, when possible, standardizing light and brightness settings in FEES research and clinical reporting.