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Comparative Evaluation of Four Different Infusion Rates of Ropivacaine (2 mg/mL) for Epidural Labor Analgesia
  1. Martin G. Cascio, M.D.*,
  2. Robert R. Gaiser, M.D.,
  3. William R. Camann, M.D.,
  4. Prema Venkateswaran, M.D.§,
  5. Joy Hawkins, M.D. and
  6. Daniel McCarthy, B.S.
  1. *From the Department of Anesthesiology, Magee-Womens Hospital, Pittsburgh, Pennsylvania;
  2. Department of Anesthesiology, Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania;
  3. Department of Anesthesiology, Brigham & Women’s Hospital, Boston, Massachusetts;
  4. §Department of Anesthesiology, University of Cincinnati Medical Center, Cincinnati, Ohio
  5. Department of Anesthesiology, University of Colorado Health Science Center, Denver, Colorado; and the
  6. Astra USA, Inc., Westborough, Massachusetts.
  1. Reprint requests: Martin G. Cascio, M.D., Benedictine Hospital, 105 Marys Avenue, Kingston, NY 12401.


Background and Objectives Previous studies have reported comparable efficacy for ropivacaine and bupivacaine when used for labor analgesia at concentrations of 2.5 mg/mL. In this multicenter study, we assessed ropivacaine at the commercially available concentration of 2 mg/mL (0.2%) for labor pain management.

Methods After Institutional Review Board approval and informed consent, 128 women at term were randomly assigned to receive ropivacaine at one of the four infusion rates via a lumbar epidural catheter. Analgesia was initiated with a 5-mL test dose, followed by injections of 5-15 mL of 2 mg/mL ropivacaine. The continuous infusion was then started at 4, 6, 8, or 10 mL/hour. Rescue analgesia was provided with 5-mL “top-up” injections as necessary to provide maternal comfort. Pain relief was assessed by using a visual analog pain scale (VAPS) and motor block was assessed by using a modified Bromage scale.

Results All infusion regimens effectively decreased VAPS, and most patients in all groups had minimal or no motor block at the end of the first stage of labor. Mean total number of the top-up injections required per patient were 3, 2, 1.5, and 1.4, respectively, in the 4, 6, 8, and 10-mL/hour groups (P < .05, 4 mL/hour vs. all other groups). Despite receiving more total bolus dosages, the 4-mL/hour group had less motor block in the lower extremities (P < .05). Apgar scores and neurological adaptive capacity scores were similar for all groups.

Conclusions The 2 mg/mL of ropivacaine produces satisfactory labor analgesia at epidural infusion rates of 4, 6, 8, and 10 mL/hour, provided supplemental bolus dosages are available. Clinically, a rate of 6 mL/hour may be the lowest effective rate that provides the best combination of pain relief, motor block, and rebolusing, although rates of 8 and 10 mL/hour produced similar results.

  • regional anesthesia
  • ropivacaine
  • epidural analgesia
  • labor
  • pregnancy
  • visual analog pain scale

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  • Presented at the International Anesthesia Research Society 71st Clinical and Scientific Congress, San Francisco, CA, March 14-18, 1997.

    This work was sponsored by a research grant from Astra Pain Control AB, Södertälje, Sweden.