Method and apparatus to measure blood flow in hemodialysis shunts

• US 7,297,280 B2
• Filed: 06/18/2004
• Issued: 11/20/2007
• Est. Priority Date: 09/16/1994
• Status: Expired due to Fees

• Current Assignee: Transonic Systems, Inc. (Measurement Innovations Corp.)
• Original Assignee: Transonic Systems, Inc. (Measurement Innovations Corp.)
• Inventors: Krivitski, Nikolai M., MacGibbon, David R.
• Primary Examiner(s): KIM, SUN U
• Application Number:
  US10/871,319
• Publication Number:
  US 20050051496A1
• Time in Patent Office: 1,250 Days
• Field of Search: 210/85, 210/87, 210/90, 210/97, 210/646, 210/739, 210/745, 604/4.01, 604/5.01, 600/504, 600/505, 738/61, 738/610.5, 738/610.7, 738/611.8
• US Class Current: 210/739
• CPC Class Codes: A61B 5/0275 using tracers, e.g. dye dilution
• CPC Class Codes: A61M 1/16 with membranes
• CPC Class Codes: A61M 1/3623 Means for actively controlling temperature of blood
• CPC Class Codes: A61M 1/3653 Interfaces between patient blood circulation and extra-corporal blood circuit
• CPC Class Codes: A61M 1/3655 Arterio-venous shunts or fistulae
• CPC Class Codes: A61M 1/3658 Indicating the amount of purified blood recirculating in the fistula or shunt
• CPC Class Codes: A61M 1/3663 Flow rate transducers; Flow integrators
• CPC Class Codes: A61M 1/3669 Electrical impedance measurement of body fluids; transducers specially adapted therefor
• CPC Class Codes: A61M 1/367 Circuit parts not covered by the preceding subgroups of group A61M1/3621

Abstract

The measurement of blood flow in a dialysis shunt is obtained by injection of an indicator material into a venous line leading from dialysis equipment to the shunt. The blood flow in an arterial line leading from the shunt at a location downstream of the venous line to the dialysis equipment is monitored by an arterial line sensor for the presence of the indicator material. A detector connected to the sensor provides a dilution curve in response to the presence of the indicator material and the blood flow in the shunt is calculated from the area under the dilution curve. The locations of the arterial and venous lines in the shunt can be reversed to obtain a measurement of blood recirculation from the venous line into the arterial line.

Claims

1. In a method of quantifying a flow rate through a patient blood vessel connected to an external blood circuit having a blood treatment device with a blood withdrawal line and a blood return line, the steps of:

(a) connecting the blood return line from the blood treatment device to the patient blood vessel upstream of the blood withdrawal line to the blood treatment device;

(b) establishing a value corresponding to a change in a physical parameter of the blood within the external blood circuit; and

(c) deriving the flow rate in the patient blood vessel from the established corresponding value.

2. The method of claim 1, further comprising employing a dialyzer as the blood treatment device.

3. The method of claim 1, further comprising inducing the change in the physical parameter of the blood in the blood return line.

4. The method of claim 1, further comprising sensing in the blood withdrawal line the value corresponding to the change in the physical parameter of the blood within the external blood circuit.

5. The method of claim 1, further comprising introducing an indicator into the blood return line.

6. A method of ascertaining a flow rate through a patient arterio-venous shunt connected to a blood treatment device by an arterial line directing blood from the patient arterio-venous shunt to the blood treatment device and a venous line directing blood from the blood treatment device to the patient arterio-venous shunt, the method comprising:

(a) connecting the arterial line to the patient arterio-venous shunt at a point downstream of a connection of the venous line and the arterio-venous shunt;

(b) passing a changed blood parameter from the venous line into the patient arterio-venous shunt; and

(c) ascertaining the flow rate in the patient arterio-venous shunt from a sensed change of the blood parameter in the arterial line.

7. The method of claim 6, further comprising introducing a dilution indicator into the venous line.

8. The method of claim 6, further comprising employing a dialyzer as the blood treatment device.

9. A method of ascertaining a blood flow rate through a shunt connected to an external blood treatment system by an arterial blood line and a venous blood line, the method comprising:

(a) connecting the arterial blood line to the shunt downstream of a connection of the venous blood line to the shunt;

(b) operating the external blood treatment system; and

(c) ascertaining by indicator dilution the blood flow rate through the shunt.

10. The method of claim 9, further comprising measuring an indicator dilution parameter in the arterial blood line.

11. The method of claim 9, further comprising passing an indicator from the venous line into the shunt.

12. A method comprising:

(a) measuring by indicator dilution a shunt blood flow rate in a patient arterio-venous shunt having an inlet of an arterial line carrying blood from the patient arterio-venous shunt to the dialysis equipment, downstream from an outlet of a venous line returning blood from the dialysis equipment to the patient arterio-venous shunt.

13. A method to facilitate a measurement of a blood flow rate in an arterio-venous shunt, the method comprising the step of:

(a) calculating by indicator dilution the blood flow rate in the arterio-venous shunt after connecting a first blood line which removes blood from the arterio-venous shunt for delivery to blood treatment equipment, downstream from a second blood line which returns blood from the blood treatment equipment for delivery to the arterio-venous shunt.

14. A method to quantify a blood flow rate in an arterio-venous shunt, the method comprising the step of:

(a) quantifying by indicator dilution the blood flow rate in the arterio-venous shunt operably connected to dialysis equipment by (i) a venous line returning blood to the arterio-venous shunt from the dialysis equipment and (ii) a downstream arterial line drawing blood from the arterio-venous shunt and delivering the blood to the dialysis equipment.

15. A method for configuring arterial blood line and venous blood line connections between dialysis equipment and an arterio-venous shunt for determining an arterio-venous shunt flow rate, the method comprising:

(a) changing arterial blood line and venous blood line connections to the arterio-venous shunt from a normal configuration where the arterial line is connected to the arterio-venous shunt upstream from the venous line to a reversed configuration where the arterial line is connected to the arterio-venous shunt downstream from the venous line; and

(b) determining by indicator dilution the arterio-venous shunt flow rate.

16. A method to facilitate a measurement of a blood flow rate in an arterio-venous shunt, the method comprising the step of calculating the blood flow rate in the arterio-venous shunt after connecting a first blood line which removes blood from the arterio-venous shunt for delivery to blood treatment equipment, downstream from a second blood line which returns blood from the blood treatment equipment, for delivery to the arterio-venous shunt, wherein calculating the blood flow rate in the arterio-venous shunt uses at least one of the following indicator dilution equations or an indicator dilution equation that can be derived from at least one of the following equations:

Q=V/S;

Q_shunt=V_ven/S_art−

Q_dial;

Q_shunt=Q_dial(V_ven/V_cal×

S_cal/S_art−

1);

Q_shunt=(V_ven/S_art−

V_cal/S_cal)

Q_shunt=Q_dial(S_ven/S_art−

1);

where Q is a rate of blood flow;

V is an amount of indicator;

S is an amount of change in a parameter observed in response to the introduction of an indicator;

Q_shunt is a flow rate of blood flowing through the arterio-venous shunt;

V_ven is an amount of indicator introduced into the arterio-venous shunt;

S_art is an amount of change in a blood parameter observed in an arterial line in response to the introduction of an indicator;

Q_dial is a flow rate of blood flowing through a dialyzer in the circulating system;

V_cal is a known amount of indicator;

S_cal is an amount of change in a blood parameter observed in response to the introduction of V_cal; and

S_ven is an amount of change in a blood parameter observed in a venous line in response to the introduction of an indicator.

17. A method comprising:

(a) calculating a blood flow rate in an arterio-venous shunt in response to an indicator delivered into the arterio-venous shunt by a hemodialysis treatment venous line, the hemodialysis treatment venous line connected to the arterio-venous shunt upstream from a dialysis equipment arterial line carrying blood from the arterio-venous shunt to the dialysis equipment.

18. The method of claim 17, further comprising introducing the indictor into the venous line.

19. The method of claim 17, further comprising detecting passage of the indicator in the arterial line.

20. The method of claim 17, further comprising calculating the blood flow rate in the arterio-venous shunt using at least one of the following indicator dilution equations or an indicator dilution equation that can be derived from at least one of the following equations:

Q=V/S;

Q_shunt=V_ven/S_art−

Q_dial;

Q_shunt=Q_dial(V_ven/V_cal×

S_cal/S_art1);

Q_shunt=(V_ven/S_art−

V_cal/S_cal)

Q_shunt=Q_dial(S_ven/S_art−

1);

where Q is a rate of blood flow;

V is an amount of indicator;

S is an amount of change in a parameter observed in response to the introduction of an indicator;

Q_shunt is a flow rate of blood flowing through the arterio-venous shunt;

V_ven is an amount of indicator introduced into the arterio-venous shunt;

S_art is an amount of change in a blood parameter observed in an arterial line in response to the introduction of an indicator;

Q_dial is a flow rate of blood flowing through a dialyzer in the circulating system;

V_cal is a known amount of indicator;

S_cal is an amount of change in a blood parameter observed in response to the introduction of V_cal; and

S_ven is an amount of change in a blood parameter observed in a venous line in response to the introduction of an indicator.