Single-dose intrathecal analgesia to control labour pain: is it a useful alternative to epidural analgesia?

OBJECTIVE To examine the safety and efficacy of single-dose spinal analgesia (intrathecal narcotics [ITN]) during labour. QUALITY OF EVIDENCE MEDLINE was searched and the references of 2 systematic reviews and a meta-analysis were reviewed to find articles on obstetric analgesia and pain measurement. The 33 articles selected included 14 studies, 1 meta-analysis, and 2 systematic reviews, all providing level I evidence. MAIN MESSAGE The literature supports use of ITN as a safe and effective alternative to epidural anesthesia. The recent decrease in rates of episiotomies and use of forceps during deliveries means patients require less dense perineal anesthesia. The advantage of single-dose ITN is that fewer physicians and nurses are needed to administer it even though its safety and effectiveness are comparable with other analgesics. Use of ITN is associated with a shorter first stage of labour and more rapid cervical dilation. A combination of 2.5 mg of bupivacaine, 25 microg of fentanyl, and 250 microg of morphine intrathecally usually provides a 4-hour window of acceptable analgesia for patients without complications not anticipating protracted labour. The evolution in dosing of ITN warrants a re-examination of its usefulness in modern obstetric practice. CONCLUSION Physicians practising modern obstetrics in rural and small urban centres might find single-dose ITN a useful alternative to parenteral or epidural analgesia for appropriately selected patients.