Fig. 4. Change from baseline levels in N2 latency and log reaction time (RT). The increase in RT is greater for midazolam and propofol (P < 0.001) than for fentanyl and thiopental (P < 0.05), whereas the increase in N2 latency is about the same in all sedative drugs (P < 0.05). P values indicated are from paired t tests on the change scores, maximum concentration minus baseline. PLAC = placebo; OND = ondansetron; FENT = fentanyl; THP = thiopental; MDZ = midazolam; PROP = propofol.