Fig. 1. Relation of maximal negative base excess to average infusion rate of propofol, analyzed separately for patients with and without identifiable cause of metabolic acidosis in addition to propofol. Note that the upper and lower x-axes give alternate measures of propofol dose, μg · kg−1· min−1and mg · kg−1· h−1. NS = not significant ( P > 0.05); R = Pearson product–moment correlation coefficient. Similar analyses also showed no correlation using other measures of propofol dose: total dose (mg/kg), time receiving propofol (hours), and highest infusion rate (μg · kg−1· min−1).