Fig. 2.
Duration of analgesia until first request for provider-administered supplemental bolus in subjects randomized to receive low-rate programmed intermittent epidural boluses (PIEB) at 100 ml/h or high-rate PIEB at 300 ml/h. The initiation of labor analgesia defined as intrathecal fentanyl administration is time 0. Times are censored at time of first request for provider-administered bolus analgesia or time of delivery. Circles and triangles represent first time patient requested supplemental bolus analgesia. Median (quartiles) duration until first request supplemental bolus request was 302 min (148 to 559 min) in the low-rate group and 357 min (216 to 525 min) in the high-rate group (P = 0.92).