Obstetric epidural test doses. A reappraisal.

A number of obstetric fatalities related to epidural anaesthesia have been reported recently. In each case catheter or needle misplacement had resulted in a lethal intrathecal or intravascular injection. In this review these cases and a number of other similar but nonfatal reports are examined. In many cases, essential safety checks such as the aspiration test and the test dose had not been performed before the epidural injection but in others one or both of these tests had been used and had failed to predict the complication. Safety test failures generally occurred because ineffective tests were used or because effective tests were inadequately interpreted. This is not surprising because although textbooks recommend a bewildering variety of test doses, they seldom give precise details as to how they should be conducted. A detailed test dose protocol is recommended, which will safely warn of epidural catheter and needle misplacement in the most effective manner possible. If the protocol is used, accidental subarachnoid and intravascular injections can be reduced to a minimum, but they will still occur. It is emphasised that these complications should not cause fatalities if trained personnel and adequate resuscitation facilities are available.