The fidelity and dynamic response of fluid-filled catheter systems for direct measurement of lumbar cerebrospinal fluid pressure

M. Kumar, Eric Werner, Michael J. Murray

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

Objective. The purpose of this study was to determine the fidelity of pressure signals transmitted through long, narrow (epidural) catheters inserted into the lumbar intrathecal space. Methods. Using a model of the spinal canal we tested three epidural catheters: 20-gauge Arrow, 20-gauge Abbott, 21-gauge Portex. We (1) determined the damping coefficient and natural frequency of the three catheters, (2) correlated the static pressures measured using the three catheters compared to the true pressure in the intrathecal space, and (3) compared the response time of the three catheters connected to transducers vs U-tube manometers. Results. The three catheters had high damping coefficients (α) (Arrow, 0.75; Abbott, 0.85; Portex, 1.10) and low natural frequencies (Arrow, 15.23 Hz; Abbott, 12.83 Hz; Portex, 9.09 Hz). The dynamic response characteristics of the catheter with the largest internal diameter (20-gauge Arrow) were adequate to reproduce pulsatile cerebrospinal fluid pressure reliably. Smaller catheters tracked the mean pressure, although oscillations were damped. Static pressure measurements from all three catheters showed good correlation with test pressures (r=0.99;p<0.001). Using the U-tube manometer, it required 170, 140, and 130 minutes for the Portex, Abbott, and Arrow catheters, respectively, to equilibrate with a test pressure of 30 cm H2O. The rate of rise in the U-tube manometer pressure was limited by the rate of fluid flow through the catheters. Conclusions. We found that a catheter of at least 20 gauge connected to a transducer could record pressures in the cerebrospinal fluid compartment with a high degree of fidelity. The prolonged time to reach equilibrium made U-tube manometry unsuitable for clinical use.

Original languageEnglish (US)
Pages (from-to)314-320
Number of pages7
JournalJournal of Clinical Monitoring
Volume9
Issue number5
DOIs
StatePublished - Nov 1993

Fingerprint

Cerebrospinal Fluid Pressure
Catheters
Pressure
Transducers
Spinal Canal
Manometry
Reaction Time

Keywords

  • catheters, epidural, spinal
  • Equipment: manometers

ASJC Scopus subject areas

  • Critical Care and Intensive Care Medicine

Cite this

The fidelity and dynamic response of fluid-filled catheter systems for direct measurement of lumbar cerebrospinal fluid pressure. / Kumar, M.; Werner, Eric; Murray, Michael J.

In: Journal of Clinical Monitoring, Vol. 9, No. 5, 11.1993, p. 314-320.

Research output: Contribution to journalArticle

@article{f8946e41355545f9b2afd04ed966522d,
title = "The fidelity and dynamic response of fluid-filled catheter systems for direct measurement of lumbar cerebrospinal fluid pressure",
abstract = "Objective. The purpose of this study was to determine the fidelity of pressure signals transmitted through long, narrow (epidural) catheters inserted into the lumbar intrathecal space. Methods. Using a model of the spinal canal we tested three epidural catheters: 20-gauge Arrow, 20-gauge Abbott, 21-gauge Portex. We (1) determined the damping coefficient and natural frequency of the three catheters, (2) correlated the static pressures measured using the three catheters compared to the true pressure in the intrathecal space, and (3) compared the response time of the three catheters connected to transducers vs U-tube manometers. Results. The three catheters had high damping coefficients (α) (Arrow, 0.75; Abbott, 0.85; Portex, 1.10) and low natural frequencies (Arrow, 15.23 Hz; Abbott, 12.83 Hz; Portex, 9.09 Hz). The dynamic response characteristics of the catheter with the largest internal diameter (20-gauge Arrow) were adequate to reproduce pulsatile cerebrospinal fluid pressure reliably. Smaller catheters tracked the mean pressure, although oscillations were damped. Static pressure measurements from all three catheters showed good correlation with test pressures (r=0.99;p<0.001). Using the U-tube manometer, it required 170, 140, and 130 minutes for the Portex, Abbott, and Arrow catheters, respectively, to equilibrate with a test pressure of 30 cm H2O. The rate of rise in the U-tube manometer pressure was limited by the rate of fluid flow through the catheters. Conclusions. We found that a catheter of at least 20 gauge connected to a transducer could record pressures in the cerebrospinal fluid compartment with a high degree of fidelity. The prolonged time to reach equilibrium made U-tube manometry unsuitable for clinical use.",
keywords = "catheters, epidural, spinal, Equipment: manometers",
author = "M. Kumar and Eric Werner and Murray, {Michael J.}",
year = "1993",
month = "11",
doi = "10.1007/BF01618670",
language = "English (US)",
volume = "9",
pages = "314--320",
journal = "Journal of Clinical Monitoring and Computing",
issn = "1387-1307",
publisher = "Kluwer Academic Publishers",
number = "5",

}

TY - JOUR

T1 - The fidelity and dynamic response of fluid-filled catheter systems for direct measurement of lumbar cerebrospinal fluid pressure

AU - Kumar, M.

AU - Werner, Eric

AU - Murray, Michael J.

PY - 1993/11

Y1 - 1993/11

N2 - Objective. The purpose of this study was to determine the fidelity of pressure signals transmitted through long, narrow (epidural) catheters inserted into the lumbar intrathecal space. Methods. Using a model of the spinal canal we tested three epidural catheters: 20-gauge Arrow, 20-gauge Abbott, 21-gauge Portex. We (1) determined the damping coefficient and natural frequency of the three catheters, (2) correlated the static pressures measured using the three catheters compared to the true pressure in the intrathecal space, and (3) compared the response time of the three catheters connected to transducers vs U-tube manometers. Results. The three catheters had high damping coefficients (α) (Arrow, 0.75; Abbott, 0.85; Portex, 1.10) and low natural frequencies (Arrow, 15.23 Hz; Abbott, 12.83 Hz; Portex, 9.09 Hz). The dynamic response characteristics of the catheter with the largest internal diameter (20-gauge Arrow) were adequate to reproduce pulsatile cerebrospinal fluid pressure reliably. Smaller catheters tracked the mean pressure, although oscillations were damped. Static pressure measurements from all three catheters showed good correlation with test pressures (r=0.99;p<0.001). Using the U-tube manometer, it required 170, 140, and 130 minutes for the Portex, Abbott, and Arrow catheters, respectively, to equilibrate with a test pressure of 30 cm H2O. The rate of rise in the U-tube manometer pressure was limited by the rate of fluid flow through the catheters. Conclusions. We found that a catheter of at least 20 gauge connected to a transducer could record pressures in the cerebrospinal fluid compartment with a high degree of fidelity. The prolonged time to reach equilibrium made U-tube manometry unsuitable for clinical use.

AB - Objective. The purpose of this study was to determine the fidelity of pressure signals transmitted through long, narrow (epidural) catheters inserted into the lumbar intrathecal space. Methods. Using a model of the spinal canal we tested three epidural catheters: 20-gauge Arrow, 20-gauge Abbott, 21-gauge Portex. We (1) determined the damping coefficient and natural frequency of the three catheters, (2) correlated the static pressures measured using the three catheters compared to the true pressure in the intrathecal space, and (3) compared the response time of the three catheters connected to transducers vs U-tube manometers. Results. The three catheters had high damping coefficients (α) (Arrow, 0.75; Abbott, 0.85; Portex, 1.10) and low natural frequencies (Arrow, 15.23 Hz; Abbott, 12.83 Hz; Portex, 9.09 Hz). The dynamic response characteristics of the catheter with the largest internal diameter (20-gauge Arrow) were adequate to reproduce pulsatile cerebrospinal fluid pressure reliably. Smaller catheters tracked the mean pressure, although oscillations were damped. Static pressure measurements from all three catheters showed good correlation with test pressures (r=0.99;p<0.001). Using the U-tube manometer, it required 170, 140, and 130 minutes for the Portex, Abbott, and Arrow catheters, respectively, to equilibrate with a test pressure of 30 cm H2O. The rate of rise in the U-tube manometer pressure was limited by the rate of fluid flow through the catheters. Conclusions. We found that a catheter of at least 20 gauge connected to a transducer could record pressures in the cerebrospinal fluid compartment with a high degree of fidelity. The prolonged time to reach equilibrium made U-tube manometry unsuitable for clinical use.

KW - catheters, epidural, spinal

KW - Equipment: manometers

UR - http://www.scopus.com/inward/record.url?scp=0027491217&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0027491217&partnerID=8YFLogxK

U2 - 10.1007/BF01618670

DO - 10.1007/BF01618670

M3 - Article

C2 - 8106883

AN - SCOPUS:0027491217

VL - 9

SP - 314

EP - 320

JO - Journal of Clinical Monitoring and Computing

JF - Journal of Clinical Monitoring and Computing

SN - 1387-1307

IS - 5

ER -