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Identification of the Epidural Space Using Pressure Measurement With the Compuflo Injection Pump - A Pilot Study
  1. Oscar Ghelber, M.D.a,
  2. Ralf E. Gebhard, M.D.b,*,
  3. Sejal Vora, M.D.b,
  4. Carin A. Hagberg, M.D.a and
  5. Peter Szmuk, M.D.c,d
  1. aDepartment of Anesthesiology, The University of Texas Medical School at Houston, Houston, TX
  2. bDepartment of Anesthesiology, University of Miami, Miller School of Medicine, Miami, FL
  3. cDepartment of Anesthesiology, The University of Texas Southwestern Medical School at Dallas, and The Children's Medical Center, Dallas, TX
  4. dOutcome Research Institute, Louisville, KY.
  5. *Reprint requests: Ralf E. Gebhard, M.D., Department of Anesthesiology, University of Miami Miller School of Medicine, Ryder Trauma Center T-239, Miami, FL 33136-1018. E-mail: rgebhard{at}


Background and Objectives: While epidural anesthesia (EA) is frequently used, success rate varies and complications associated with incorrect needle placement can occur. Different methods of objective identification of the epidural space (ES) have been suggested, without receiving widespread popularity. This prospective pilot study evaluated continuous pressure measurement during low speed injection with a computerized injection pump to objectively identify the ES.

Methods: While EA was performed using a conventional loss of resistance technique in 20 consecutive patients, the injection pump technology was used to obtain pressure readings from the supraspinous ligament, the ligamentum flavum, and the ES. In the next 20 patients, the epidural space was solely identified with the computerized injection pump.

Results: Pressure reading obtained during the first part of the study revealed significant differences between the ES vs. the supraspinous ligament, and the ES vs. the ligamentum flavum (8 mm Hg, 95% confidence interval [CI] 6-11 vs 79 mm Hg, 95% CI 74-83 and 92 mm Hg, 95% CI 83-102, respectively) (P < .001). In the second part of the study, the injection pump allowed for successful identification of the ES and performance of EA in all 20 patients.

Conclusions: This investigation demonstrates that a computerized injection pump can be used to identify the epidural space and can serve as a base for further comparative research to determine whether this technology can increase the success rate of EA or lower the incidence of side effects.

  • Labor analgesia
  • Success rate
  • Epidural anesthesia
  • Epidural space pressure

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  • Support was provided by the Department of Anesthesiology, The University of Texas-Houston Medical School. The Compuflo unit was provided by Milestone Scientific, Livingston, NJ. Results of this investigation were presented in part at the 2005 Meeting of the International Anesthesia Research Society in Oahu, HI, March 11-15, 2005. Dr. Gebhard has received research support and honoraria for consulting from Milestone Scientific.