FENTANYL FOR EPIDURAL INTRAVASCULAR TEST DOSE IN OBSTETRICS

Background and Objectives. Although dizziness and drowsiness may be pr oduced with either intravenous or epidural fentanyl, their occurrence after an intravenous injection is more rapid and relatively more prono unced. The purpose of this study was to determine whether or not the d ifference between routes of administration would be a reliable method of detecting an accidental intravascular injection. Methods. In part 1 , using a double-blinded protocol, we prospectively assessed in labori ng women the incidence of dizziness, drowsiness, or both associated wi th intravenous fentanyl (100 mug). In random order, subjects received two peripheral intravenous injections: 2 ml of fentanyl and 2 ml of sa line, separated by a 3-minute observation period. Results. In group 1 (18/18) and group 2 (22/22), all subjects reported a response to intra venous fentanyl within the one-minute assessment. In part 2, we evalua ted in laboring patients the frequency of dizziness, drowsiness, or bo th to epidural fentanyl (100 mug). The study design was identical to p art 1; however, the subjects received 2 ml of fentanyl and 2 ml of sal ine via a functional epidural catheter. In group 3 (1/18) and group 4 (1/22), one subject reported a response to epidural fentanyl within th e 3-minute observation period. Conclusions. Overall, the responses to intravenous fentanyl (40/40) occurred in a remarkably more consistent fashion when compared to epidural fentanyl (2/40). Thus, the results s uggest that in laboring patients, intravenous fentanyl produces predic table and easily detectable changes that may be useful in identifying an epidural catheter unintentionally placed intravascularly.