EP0226220A2
Expired / Lapsed
EP
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Mini-bolus technique for thermodilution cardiac output measurements
Assignee: General Hospital Corp
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Filing: 1986-12-18
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Granted: —
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Expires: 2006-12-18
Abstract
Abstract A composite catheter for in vivo fluid injection is provided in which a thin tube (32) is located within a lumen (18) of a conventional catheter (10). The thin tube has a small diameter inner passage (44) for the in vivo injection of a fluid to be applied through a port (48) in the catheter wall (12) into the blood stream. A sensing device, such as a thermistor (50), is mounted on the catheter downstream of the port to measure changes in the properties of the fluid resulting from fluid injection for thermodilution applications. The space (45) within the lumen (18) insulates the fluid from the catheter environment and the small bore inner passage (44) reduces residual fluid permitting small fluid injections that accommodate frequent injection measurements.
Inventors
- 👤 Ronald S. Newbower
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-04 19:33
CPC Classifications
A; A61; A61B; A61B5/00; A61B5/02; A61B5/026; A61B5/029; A61B5/0275; A61B5/028; A61B18/00; A61B2018/00053; A61B2018/00059; A61B2018/00089; A61B2018/00101; A61B2018/00166
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
97 words
A catheter for use in injection applications, comprising: a flexible outer tube having at least one lumen therethrough from a first end toward a second end; at least one flexible inner tube longitudinally extending within the lumen and adapted to pass a fluid through an inner passage of the inner tube; the inner passage having a cross-sectional area substantially less than the cross-sectional area of the lumen; and the catheter assembly providing greater thermal insulation between the exterior of the outer tube and the inner passage than between the exterior of the outer tube and the lumen.
Claim 2
Dependent Claim
97 words
A catheter for use in injection applications, comprising: a flexible outer tube having at least one lumen therethrough from a first end toward a second end; at least one flexible inner tube longitudinally extending within the lumen and adapted to pass a fluid through an inner passage of the inner tube; the inner passage having a cross-sectional area substantially less than the cross-sectional area of the lumen; and the catheter assembly providing greater thermal insulation between the exterior of the outer tube and the inner passage than between the exterior of the outer tube and the lumen.
Claim 3
Dependent Claim
21 words
The catheter of claim 1 wherein the inner passage communicates to the exterior of the outer tube toward the second end.
Claim 4
Dependent Claim
25 words
The catheter of claim 1, and further including at least one thermistor probe and associated thermistor leads extending within at least one of said lumens.
Claim 5
Dependent Claim
27 words
. The catheter of claim 2, wherein the inner passage communicates to the exterior of the outer tube by way of a port in the outer tube.
Claim 6
Dependent Claim
29 words
The catheter of claim 1, wherein the enclosing wall of said lumen is configured to minimize thermal loss between contacting portions of the inner tube and the outer tube.
Claim 7
Dependent Claim
20 words
The catheter of claim 1, further including means for maintaining a separation between the outer tube and said inner tube.
Claim 8
Dependent Claim
11 words
The catheter of claim 6, wherein said maintaining means includes filament.
Claim 9
Dependent Claim
10 words
The catheter of claim 1, wherein said lumen is air-filled.
Claim 10
Dependent Claim
19 words
The catheter of claim 1, wherein said inner passage has a fluid volume approximately no greater than 0.1 cc's.
Claim 11
Independent Claim
105 words
A method of injecting small volume, high accuracy fluids for thermodilution measurement using a catheter having an outer tube with at least one lumen therethrough from a first end toward a second end, comprising the steps of: injecting a fluid through an inner tube within said lumen, said inner tube being of cross-sectional area substantially smaller than the cross-sectional area of said lumen; porting the injected fluid from said inner tube to the exterior of said outer tube into a flowing stream of fluid under study; and insulating the exterior of the outer tube from the interior of the inner tube to reduce thermal loss.
Claim 12
Independent Claim
105 words
A method of injecting small volume, high accuracy fluids for thermodilution measurement using a catheter having an outer tube with at least one lumen therethrough from a first end toward a second end, comprising the steps of: injecting a fluid through an inner tube within said lumen, said inner tube being of cross-sectional area substantially smaller than the cross-sectional area of said lumen; porting the injected fluid from said inner tube to the exterior of said outer tube into a flowing stream of fluid under study; and insulating the exterior of the outer tube from the interior of the inner tube to reduce thermal loss.
Claim 13
Dependent Claim
23 words
The method of claim 10, further including the step of porting the fluid from said inner tube in the direction of said stream.
Claim 14
Dependent Claim
22 words
The method according to claim 10, further including the step of limiting the injection to approximately a fluid volume of 1.0 cc's.
Claim 15
Dependent Claim
47 words
The method of claim 10 further including the steps of: repeatedly injecting fluid volumes; detecting a parameter representative of a cardiac function from thermodilution effects for each injected volume; and averaging the detected parameter for each injection to achieve a statistically enhanced signal-to-noise ratio in the average.
Claim 16
Independent Claim
87 words
A method for improving the signal-to-noise ratio in an in vivo patient indicator dilution system comprising: applying plural small injections of a fluid injectate which in the aggregate volume does not exceed a predetermined volume deemed acceptable to the patient; detecting a parameter representative of cardiac function for each of the plural small injections; statistically averaging the detected parameters to achieve a signal-to-noise ratio in the average greater than the signal-to-noise ratio that would be achieved with a single injectate of volume equal to the aggregate volume.
Claim 17
Independent Claim
87 words
A method for improving the signal-to-noise ratio in an in vivo patient indicator dilution system comprising: applying plural small injections of a fluid injectate which in the aggregate volume does not exceed a predetermined volume deemed acceptable to the patient; detecting a parameter representative of cardiac function for each of the plural small injections; statistically averaging the detected parameters to achieve a signal-to-noise ratio in the average greater than the signal-to-noise ratio that would be achieved with a single injectate of volume equal to the aggregate volume.
Claim 18
Dependent Claim
41 words
The method of claim 14 wherein the aggregate volume is such that if each of the plural injections were of a volume equal to the aggregate volume, the then aggregate volume would exceed a predetermined volume deemed excessive for the patient.
References Cited (Backward Citations)
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