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Bolus epidural infusion improves spread compared with continuous infusion in a cadaveric porcine spine model
  1. Jacob Cole and
  2. Scott Hughey
  1. Anesthesiology and Pain Medicine, Naval Medical Center Portsmouth, Portsmouth, Virginia, USA
  1. Correspondence to Dr Jacob Cole, Anesthesiology and Pain Medicine, Naval Medical Center Portsmouth, Portsmouth, VA 23708, USA; cole.jacob.h{at}


Background The administration of epidural anesthesia during labor is a common technique used to reduce the pain of childbirth. We sought to compare standard infusion strategies of continuous epidural infusions (CEI) with programmed intermittent epidural bolus (PIEB) to assess the length of spread in terms of vertebral body length. Based on previous clinical data in humans, the PIEB was associated with improved pain control and decreased total dose of local anesthetic. We hypothesized that the PIEB was associated with increased spread when compared with CEI.

Methods Thirty female Yorkshire-cross swine cadavers were used to compare three infusion strategies, continuous infusion (CEI) 10 mL/hour programmed continuously, multiple bolus (MB) 2 mL given every 12 min for 10 mL total and 10 mL delivered in a single bolus (SB). Radiographs were used to identify the spread of the radiopaque contrast dye, and a number of vertebral bodies covered were measured to assess spread.

Results Overall, the CEI had an average spread of 5.6 levels, MB 7.9 and SB 10.4. The differences between SB and MB (p=0.011), SB and CEI (p<0.001) and MB and CEI (p=0.028) were all found to be significant.

Conclusions We demonstrated increased spread of epidural contrast with programmed intermittent bolus strategies. This supports previous evidence of improved patient outcomes with PIEB strategy compared with CEI, and encourages the use of PIEB in the appropriate patient population.

  • neuraxial blocks: continuous techniques
  • neuraxial blocks: epidural
  • obstetrics

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  • Contributors Both authors contributed equally to the conception, planning, design, execution and data analysis required in the performance of this study and the preparation of this manuscript.

  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Competing interests None declared.

  • Patient consent for publication Not required.

  • Ethics approval This study was conducted using swine carcasses acquired via tissue sharing agreements with protocols approved by the Naval Medical Center Portsmouth (NMCP) Institutional Animal Care and Use Committee (IACUC). The IACUC deemed that this study was exempt from review.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Data availability statement Data are available on reasonable request.

  • Author note We are military service members and an employee of the US Government. This work was prepared as part of our official duties. Title 17 U.S.C. 105 provides that 'Copyright protection under this title is not available for any work of the US Government.' Title 17 U.S.C. 101 defines a US Government work as a work prepared by a military service member or employee of the US Government as part of that person’s official duties.