Fig. 3. Effects of infraclavicular perineural ropivacaine infusion dosing regimen on sleep disturbances after moderately painful surgery of the upper extremity. Endpoints included difficulty sleeping because of pain (A ), number of awakenings because of pain (B ), and number of bolus doses self-administered between 11 pm and 7 am (C ). The catheters were discontinued as indicated by the horizontal boxes . (A ) Data are expressed as fraction of patients reporting difficulty sleeping because of pain. (B and C ) Data are expressed as median (horizontal bars ) with 25th–75th (boxes ) and 10th–90th (whiskers ) percentiles for patients randomly assigned to the basal group (basal rate, 12 ml/h; bolus dose, 0.05 ml; lockout, 1 h; n = 10) the basal–bolus group (basal rate, 8 ml/h; bolus dose, 4 ml; lockout, 1 h; n = 10), or the bolus group (basal rate, 0.3 ml/h; bolus dose, 9.9 ml; lockout, 1 h; n = 10). For tightly clustered data (e.g. , C , postoperative day 0, basal group), the median approximated the 10th and 25th percentile values. In this case, the median is 0.0, and only the 75th and 90th percentiles are clearly noted. P < 0.05 for group comparisons for a given postoperative day:* basal–bolus group versus bolus group; † bolus group versus basal group; § comparing all groups for a given day using chi-square analysis.