The exact mode of administration of boluses is also subject to discussion in the literature. One can question whether it is preferable to administer smaller boluses more frequently or larger less frequent boluses. A few studies have investigated this issue and recommend to administer larger and more spaced bolus (10 mL to 60 minutes).This better matches the sought after physiology (ie a wider distribution in the epidural space) and provides equivalent analgesia to smaller, more frequent boluses.