Assessment of recovery after intravenous sedation using a gaze-tracking system

Objectives: To investigate the possibilities of using gaze analysis to assess wakefulness coming out of sedation, we used a monitor integrated gaze-tracking system to track a subject’s gaze during a particular video while recovering after sedation, then performed quantitative analysis on the data obtained.
Methods: The subjects were 28 healthy adult male volunteers (24.2±2.96 years old (mean ± standard deviation)) who underwent intravenous sedation using midazolam (0.05 mg/kg). Romberg’s test was performed and clinical findings were assessed every 10 minutes after the start of sedation up to 120 minutes. Next, the volunteers were sat in front of a monitor integrated gaze-tracking system ("Gazefinder" NP-100: JVC KENWOOD Corp.) to track the movements and concentration of their gaze on a visual target during a particular video shown on the monitor to calculate visual target capture rates at each measurement point. Freidman test was performed on the capture rates before sedation and at each measurement point. The significance level was set to 5%.
Results: Before sedation, the visual target capture rate was 85.1±17.6% and Romberg’s test score was 0.00±0.00. The mean Romberg’s test scores from 10 to 80 minutes after the start of sedation were significantly lower than before sedation. The visual target capture rates from 10 to 100 minutes after the start of sedation were significantly lower than before sedation, which indicates that Romberg’s test scores tended to recover faster than visual target capture rates. At 100 minutes the visual target capture rate had returned to the 70% level and at 120 minutes it was 76.4±21.7%.
Conclusions: The results of the present study indicate that when assessing patients coming out of sedation, using a monitor integrated gaze-tracking system to follow the gaze as it tracks a visual target during a particular video could be used as an objective criteria for assessing recovery after sedation.