Figure 1. Slope of carbon dioxide response curves' (x with bar +/- SE). Because they did not differ between flumazenil and placebo trials, pooled values are shown for the baseline, alfentanil, and midazolam/alfentanil determinations. (A) P < 0.05 versus baseline. (B) P < 0.05 versus alfent. (C) P < 0.05 versus mdz + alfent. (D) P <0.05 change from mdz + alfent with flumazenil versus change from mdz + alfent with placebo.