Reaction time course during weaning from respirator treatment

Ten patients who developed disturbed mental function during respirator weaning were studied. They were investigated during respirator treatment and 1 h after start of spontaneous ventilation with continuous reaction time measurements and clinical ratings. During the spontaneous ventilation the reaction times increased and the patients experienced fatigue. PaCO2 was higher and PaO2 was lower than during respirator treatment. A significant correlation was found between individual differences of reaction times and arterial blood gas levels in the two conditions, whereas no general correlation between reaction times and arterial blood gas levels could be established. The findings must be considered tentative, but the results of this study indicate the value of continuous reaction time measurements for quantitative assessment of mental status during respirator treatment.