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Barriers and methods for pressure measurement catheters

a technology of pressure measurement and barriers, applied in the field of medical devices and methods, to achieve the effect of improving viscoelastic barrier materials, and facilitating the measurement of pressur

Inactive Publication Date: 2009-01-29
TRANSOMA MEDICAL
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The present invention provides improved viscoelastic barrier materials for making pressure measurement catheters. These materials have several advantages, such as being soft enough to easily place within a catheter, having high cross-linking to prevent washout, and being simple to produce consistently. The barrier materials are prepared by combining a barrier material precursor with a softener, such as dimethyl silicone oil. The resulting barrier materials have desirable properties such as softness and low hysteresis. The methods and apparatus of the invention allow for easy placement of the barrier materials within a catheter and minimize fluid leakage. The invention also provides methods for making the viscoelastic barrier materials.

Problems solved by technology

Third, an ideal barrier material will be relatively simple to produce in a consistent manner, so that individual batches of the material are largely similar and complex fabrication techniques are not required.

Method used

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  • Barriers and methods for pressure measurement catheters
  • Barriers and methods for pressure measurement catheters
  • Barriers and methods for pressure measurement catheters

Examples

Experimental program
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Effect test

example 1

Material Stability Testing

[0092]The purpose of this investigation was to measure viscosity of NuSil Gel-8000, prepared in 1:1 ratio and combined with 42% MED-361 silicone oil at 12,500 cps, by weight, at room temperature (˜25° C.) and body temperature (˜37° C.) over the course of a year. Certain measures of viscosity, such as change in viscosity over time measured as standard deviation from an average viscosity, may correlate with stability of a barrier material.

[0093]First, NuSil Gel-8000 was prepared in a 1:1 ratio of 35 g (+ / −0.1 g) of part A to 35 g (+ / −0.1 g) of part B, and the combination was mixed with an electric mixer set to 10, for ten minutes. MED-361 silicone oil at 12,500 cps was then added to the 70 g (+ / −0.1 g) Gel-8000, in an amount of 42% by weight, or 29.4 g (+ / −0.1 g), to form a total weight for the combined substance of 99.4 g (+ / −0.1 g). The combined substance was then placed in a conventional centrifuge and centrifuged at 1000 rpm for two minutes. Immediately o...

example 2

Barrier Washout Testing

[0096]The purpose of this investigation was to establish a washout range in vitro with the NuSil Gel-8000 / MED-361 silicone oil, prepared as described above. Barrier material was placed in several pressure transmission catheter devices to form barriers and washout (or “recession”) was measured at 0, 2, 4 and 6 weeks. For comparison, a number of catheters were prepared with Dow Q7-2218 gel, prepared off ratio at between about 1.65:1 and about 1.90:1 to provide sufficient softness and having no silicone oil added. The Harvard Pulsatile Blood Pump™ was used to simulate the ventricular action of the heart through the manipulation of the flow rate. A water and glycerol solution was used to replicate the viscosity of blood.

[0097]Every two weeks, at 0, 2, 4 and 6 weeks, barrier recession and length was measured in each transmitter with a ruler, reticule and microscope. (Barrier recession was measured with the reticule and barrier length with the ruler.) The Harvard Pu...

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Abstract

Methods and apparatus of the present invention provide viscoelastic barrier materials for use as barriers in devices such as pressure measurement catheters. Improved barrier materials sometimes include at least one barrier material precursor combined with an amount of a softener. In other embodiments, two barrier material precursor components are combined without a softener to provide a fully cross-linked barrier material having certain softness characteristics. In various embodiments, a softener may be dimethyl silicone oil and may be combined with a barrier material precursor in an amount of between about 25% and about 45% by weight, relative to the final barrier material. Once a viscoelastic barrier material is prepared, it may be placed in a pressure transmission catheter or similar device, for example by injecting the gel into a lumen of the catheter via a syringe. Barrier materials of the present invention have one or more advantageous properties, such as a desired softness, full cross-linking, resistance to washout from a catheter, enhanced stability and / or the like.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application is a continuation in part application of and claims priority to U.S. application Ser. No. 10 / 272,489, filed on Oct. 15, 2002, which is herein incorporated by reference in its entirety.BACKGROUND OF THE INVENTION[0002]The present invention relates generally to medical devices and methods. More specifically, the invention relates to improved barriers for use in pressure measurement catheters, and methods for making and using the improved barriers.[0003]Implantable pressure measurement devices such as pressure measurement catheters may be used in a wide variety of contexts to measure many types of pressures in human patient care, veterinary or research environments. Pressure measurement catheters may be used, for example, to measure pressures in a human or animal including endocardial, arterial, venous, cerebral, intraocular, urinary, intrauterine, penile, thoracic cavity and various other vascular or tissue pressures. Measu...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): A61M31/00A61L33/06A61B5/00A61B5/0215A61B5/03
CPCA61B5/0002A61B5/036A61B5/031A61B5/0215
Inventor STOFER, ALYSE RENEEZWEIRS, LYNN MARLO
Owner TRANSOMA MEDICAL
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