An in vitro evaluation of the pressure generated during programmed intermittent epidural bolus injection at varying infusion delivery speeds.
OBJECTIVE
Programmed intermittent bolus injection of epidural anesthetic solution results in decreased anesthetic consumption and better patient satisfaction compared with continuous infusion, presumably by better spread of the anesthetic solution in the epidural space. It is not known whether the delivery speed of the bolus injection influences analgesia outcomes. The objective of this in vitro study was to determine the pressure generated by a programmed intermittent bolus pump at 4 infusion delivery speeds through open-ended, single-orifice and closed-end, multiorifice epidural catheters.


METHODS
In vitro observational study.


METHODS
Not applicable.


METHODS
Not applicable.


METHODS
A CADD-Solis Pain Management System v3.0 with Programmed Intermittent Bolus Model 2110 was connected via a 3-way adapter to an epidural catheter and a digital pressure transducer. Pressures generated by delivery speeds of 100, 175, 300, and 400 mL/h of saline solution were tested with 4 epidural catheters (2 single orifice and 2 multiorifice). These runs were replicated on 5 pumps. Analysis of variance was used to compare the mean peak pressures of each delivery speed within each catheter group (single orifice and multiorifice).


RESULTS
Thirty runs at each delivery speed were performed with each type of catheter for a total of 240 experimental runs. Peak pressure increased with increasing delivery speeds in both catheter groups (P<.001). Peak pressures were higher with the multiorifice catheter compared with the single-orifice catheter at all delivery speeds (P<.001, for all).


CONCLUSIONS
Using a pump designed for programmed intermittent infusion boluses, the delivery speed of saline solution through epidural catheters was directly related to the peak pressures. Future work should evaluate whether differences in the delivery speed of anesthetic solution into the epidural space correlate with differences in the duration and quality of analgesia during programmed intermittent epidural bolus delivery.
Department of Anesthesiology, Northwestern University Feinberg School of Medicine, 251 E Huron St, F5-704, Chicago, IL, USA 60611; Department of Anesthesiology, University of Michigan, 1H247, University Hospital, 1500 East Medical Center Drive, Ann Arbor, MI, USA 48109-5048.
Thomas T
TT
Klumpner
Department of Anesthesiology, Northwestern University Feinberg School of Medicine, 251 E Huron St, F5-704, Chicago, IL, USA 60611. Electronic address: elizabeth.lange@northwestern.edu.
Elizabeth M S
EM
Lange
Department of Anesthesiology, Northwestern University Feinberg School of Medicine, 251 E Huron St, F5-704, Chicago, IL, USA 60611.
Heena S
HS
Ahmed
Department of Anesthesiology, Northwestern University Feinberg School of Medicine, 251 E Huron St, F5-704, Chicago, IL, USA 60611.
Paul C
PC
Fitzgerald
Department of Anesthesiology, Northwestern University Feinberg School of Medicine, 251 E Huron St, F5-704, Chicago, IL, USA 60611; Department of Anesthesia, University of Iowa Carver College of Medicine, 200 Hawkins Drive, Iowa City, IA, USA, 52242-1009.
Cynthia A
CA
Wong
Department of Anesthesiology, Northwestern University Feinberg School of Medicine, 251 E Huron St, F5-704, Chicago, IL, USA 60611; Center for Health Care Studies, Northwestern University Feinberg School of Medicine, 633 N. Saint Clair, 20th floor, Chicago, IL, USA 60611.
Paloma
P
Toledo
D015360:Analgesia, Epidural / Q000379:methods*; D016362:Analgesia, Obstetrical / Q000379:methods*; D000767:Anesthesia, Epidural / Q000379:methods*; D000779:Anesthetics, Local / Q000008:administration & dosage*; D057785:Catheters; D005260:Female; D006801:Humans; D007260:Infusion Pumps; D007268:Injections, Epidural / Q000295:instrumentation / Q000379:methods; D059408:Pain Management / Q000379:methods*; D017060:Patient Satisfaction; D011312:Pressure
D000779:Anesthetics, Local
Epidural infusion pumps; Pressure; Programmed intermittent epidural bolus