[Failure of obstetric epidural analgesia and its causes]

The frequency of failure to establish and maintain an epidural block is low in Spain for surgery but higher in obstetrics. The reasons are many, but noteworthy factors are the prior experience of the anesthesiologist, the anatomical features of the patient and the type of material used. However, we lack clinical and anatomical studies of the epidural space that would allow us to come to definitive conclusions. To reduce the number of failures in obstetrical analgesia, multi-holed catheters are recommended. Material and catheter permeability should be checked before puncture. The epidural needle should be directed toward the midline, air should not be injected into the epidural space. The anesthesiologist should avoid inserting too much of the epidural catheter and should assure firm support, checking it periodically and taking into account the patient's position. Finally the anesthetic dose should be adjusted to the progress of labor. The risk of incomplete analgesia and the possible need to insert a second epidural catheter must be discussed with the patient during preanesthetic evaluation.