Method and apparatus to determine an initial flow rate in a conduit

• US 7,121,150 B2
• Filed: 03/18/2005
• Issued: 10/17/2006
• Est. Priority Date: 10/19/1999
• Status: Expired due to Term

• Current Assignee: Transonic Systems, Inc. (Measurement Innovations Corp.)
• Original Assignee: Transonic Systems, Inc. (Measurement Innovations Corp.)
• Inventors: Krivitski, Nikolai M., Drost, Cornelis J.
• Primary Examiner(s): PATEL, HARSHAD R
• Application Number:
  US11/084,271
• Publication Number:
  US 20050166683A1
• Time in Patent Office: 578 Days
• Field of Search: 738/610.5, 738/61
• US Class Current: 73/861
• CPC Class Codes: A61B 5/0215 by means inserted into the body catheters A61M25/00
• CPC Class Codes: A61B 5/0255 Recording instruments specially adapted therefor
• CPC Class Codes: A61B 5/026 Measuring blood flow A61B3/1233, A61B3/1241 take precedence
• CPC Class Codes: A61B 5/027 using catheters
• CPC Class Codes: A61B 5/0275 using tracers, e.g. dye dilution
• CPC Class Codes: A61B 5/6852 Catheters
• CPC Class Codes: A61M 25/00 Catheters; Hollow probes dilators A61M29/00; peritoneal catheters A61M1/285; tracheal tubes A61M16/04; for drainage A61M27/00; for uterus, vagina or rectum A61M31/00 ; for measuring or testing A61B; materials for catheters A61L29/00
• CPC Class Codes: G01F 1/34 by measuring pressure or differential pressure
• CPC Class Codes: G01F 1/66 by measuring frequency, phase shift or propagation time of electromagnetic or other waves, e.g. using ultrasonic flowmeters
• CPC Class Codes: G01F 1/704 using marked regions or existing inhomogeneities within the fluid stream, e.g. statistically occurring variations in a fluid parameter G01F1/76, G01F25/00 take precedence
• CPC Class Codes: G01F 1/708 Measuring the time taken to traverse a fixed distance
• CPC Class Codes: G01F 25/10 of flowmeters

Abstract

A method and apparatus for determining an initial flow rate in a conduit is disclosed. A known change is made to the flow to be measured, resulting changes (or values corresponding to these changes), or relative changes in the flow to be measured are monitored and the initial flow in the conduit is calculated from the value of the known change and monitored changes. Devices to practice the method include catheters having one or two sensors and one or two sites for introducing the volume change.

Claims

1. An apparatus for determining an initial flow rate in a conduit, comprising:

(a) means for introducing a volume change to the initial flow rate;

(b) an upstream sensor monitoring a change to the flow upstream of the introduced volume change;

(c) a downstream sensor monitoring a change in the flow downstream of the introduced volume change; and

(d) a controller in communication with the upstream sensor and the downstream sensor for determining the initial flow rate.

2. The apparatus of claim 1, wherein the upstream sensor measures a first flow characteristic and the downstream sensor measures a different second flow characteristic.

3. The apparatus of claim 1, further comprising a catheter, the upstream sensor and the downstream being connected to the catheter.

4. The apparatus of claim 1, wherein the upstream sensor creates an upstream sensing zone.

5. The apparatus of claim 1, wherein the downstream sensor creates a downstream sensing zone.

6. The apparatus of claim 1, wherein the controller determines the initial flow rate corresponding to the equation and analogous relationships,

$Q=\frac{\mathrm{Qi}}{\mathrm{Cd}-\mathrm{Cu}},$

where Qi is the volume change flow rate, Cd is the relative change in a flow corresponding parameter downstream from a location of flow change, Cu is the relative change in a flow corresponding parameter upstream from the location of the flow change, and a Q is the initial flow rate.

7. The apparatus of claim 1, wherein the means for introducing a volume change to the initial flow rate includes a catheter having an infusion port.

8. A method of determining an initial flow rate in a conduit, comprising:

(a) introducing a volume change at a location in the initial flow;

(b) monitoring a resulting change upstream of the location;

(c) monitoring a resulting change downstream of the location; and

(d) determining the initial flow rate corresponding to the monitored upstream change, the monitored downstream change and the introduced volume change.

9. The method of claim 8, further comprising determining the initial flow rate corresponding to the equation and analogous relationships,

$Q=\frac{\mathrm{Qi}}{\mathrm{Cd}-\mathrm{Cu}},$

where Qi is the volume change flow rate, Cd Is the relative change in a flow corresponding parameter downstream from a location of flow change, Cu is the relative change in a flow corresponding parameter upstream from the location of the flow change, and a Q is the initial flow rate.

10. An apparatus far determining an initial flow rate in a conduit, comprising:

(a) means for introducing a volume change to the conduit;

(b) an upstream sensor upstream of the introduced volume change, the upstream sensor measuring a change corresponding to the introduced volume change;

(c) a downstream sensor downstream of the introduced volume change, the downstream sensor measuring a change corresponding to the introduced volume change; and

(d) a controller in communication with the upstream sensor and the downstream sensor, the controller configured to determine the initial flow rate in response to the measured changes.

11. The apparatus of claim 10, wherein the controller determines the initial flow rate corresponding to the equation and analogous relationships,

$Q=\frac{\mathrm{Qi}}{\mathrm{Cd}-\mathrm{Cu}},$

where Qi is the volume change flow rate, Cd is the relative change in a flow corresponding parameter downstream from a location of flow change, Cu is the relative change in a flow corresponding parameter upstream from the location of the flow change, and a Q is the initial flow rate.

12. The apparatus of claim 10, wherein the means for introducing a volume change to the conduit includes a catheter having an infusion port.

13. A method for determining an initial flow rate in a conduit, comprising:

(a) introducing a volume change to the initial flow at a location intermediate an upstream pressure sensor and a downstream pressure sensor; and

(b) determining the initial flow rate corresponding to a pressure sensed at the upstream pressure sensor and the downstream pressure sensor.

14. An apparatus for determining an initial flow rate in a conduit, comprising:

(a) a known flow rate producer introducing a volume change to the initial flow rate;

(b) a first sensor upstream of the introduced volume change, the first sensor measuring an upstream change corresponding to the introduced volume change;

(c) a second sensor downstream of the introduced volume change, the second sensor measuring a downstream change corresponding to the introduced volume change; and

(d) a controller in communication with the first sensor and the second sensor, the controller configured to determine the initial flow rate in response to the measured upstream and downstream changes.

15. The apparatus of claim 14, wherein the first sensor measures one of a flow characteristic and a liquid characteristic.

16. The apparatus of claim 14, wherein the first sensor measures one of an optical property, electrical property, thermal property, acoustic property, pressure, sound velocity and Doppler frequency.

17. The apparatus of claim 14, wherein the second sensor measures one of a flow characteristic and a liquid characteristic.

18. The apparatus of claim 14, wherein the second sensor measures one of an optical property, electrical property, thermal property, acoustic property, pressure, sound velocity and Doppler frequency.

19. The apparatus of claim 14, wherein the controller determines the initial flow rate Q, corresponding to at least one of the following and an analogous relationships:

$Q=\frac{Q_i}{\left(\frac{\mathrm{\Delta <br><br>}<br><br><br><br>Q_d}{Q_d}-\frac{\mathrm{\Delta <br><br>}<br><br><br><br>Q_u}{Q_u}\right)};<br><br><br><br>Q=\frac{Q_i}{\left(C_{\mathrm{bd}}-C_{\mathrm{bu}}\right)};<br><br><br><br>Q=\frac{Q_i}{\left(\frac{\mathrm{\Delta <br><br>}<br><br><br><br>V_d}{V_d}-\frac{\mathrm{\Delta <br><br>}<br><br><br><br>V_u}{V_u}\right)};<br><br>$ $Q=\frac{Q_i}{\left(\frac{\mathrm{\Delta <br><br>}<br><br><br><br>\mathrm{hu}}{\mathrm{hui}}-\frac{\mathrm{\Delta <br><br>}<br><br><br><br>\mathrm{hd}}{\mathrm{hdi}}\right)};<br><br><br><br>Q=\frac{Q<br><br><br><br>i}{\left(\frac{\mathrm{\Delta <br><br>}<br><br><br><br>\mathrm{Pd}}{\mathrm{Pd}-\mathrm{Pven}}-\frac{\mathrm{\Delta <br><br>}<br><br><br><br>\mathrm{Pu}}{\mathrm{Pu}-\mathrm{Part}}\right)}$

where Q_i is the introduced volume during the introduced time;

Δ

Q_d=Q_di−

Q_d;

Δ

Q_u=Q_ui−

Q_u;

Q_d is the flow rate downstream of the introduced volume change Q_l;

Q_u is the flaw rate upstream of the introduced volume change Q_l;

C_bd is the relative change in a flow corresponding parameter from an upstream introduced volume change;

C_bu is the relative change in a flow corresponding parameter from a downstream introduced volume change;

Δ

V_u is a change corresponding to an upstream flow velocity;

Δ

V_d is a change corresponding to a downstream flow velocity;

V_u is an upstream flow velocity;

V_d is a downstream flow velocity;

hu is a concentration of indicator measured at an upstream sensor;

hd is a concentration of indicator measured at a downstream sensor;

Δ

hu=hui−

hu; and

Δ

hd=hdi−

hd.