Managing Cross-contamination in Blood Samples Withdrawn from a Multilumen Catheter

• US 20090048576A1
• Filed: 09/25/2007
• Published: 02/19/2009
• Est. Priority Date: 08/13/2007
• Status: Abandoned Application

• Current Assignee: Luminous Medical, Inc.
• Original Assignee: Luminous Medical, Inc.
• Inventors: Tobler, Dave, Borrello, Mike, Robinson, Mark Ries, Thompson, Richard, O'Mahony, John, Grafe, V. Gerald
• Application Number:
  US11/860,544
• Publication Number:
  US 20090048576A1
• Time in Patent Office: Days
• US Class Current: 604/508
• CPC Class Codes: A61B 5/14532 for measuring glucose, e.g. by tissue impedance measurement
• CPC Class Codes: A61B 5/15003 for venous or arterial blood
• CPC Class Codes: A61B 5/150213 Venting means
• CPC Class Codes: A61B 5/150221 Valves
• CPC Class Codes: A61B 5/150229 Pumps for assisting the blood sampling
• CPC Class Codes: A61B 5/150961 Means for the detection of the presence or absence of a module, a component or an abnormal condition; detection of leaks
• CPC Class Codes: A61B 5/155 Devices specially adapted for continuous or multiple sampling, e.g. at predetermined intervals devices loaded with multiple lancets simultaneously A61B5/15146
• CPC Class Codes: A61B 5/157 Devices characterised by integrated means for measuring characteristics of blood

Abstract

The present invention comprises methods and apparatuses that can provide accurate measurement of glucose or other analytes from a multilumen catheter in the presence of infusion of substances, including glucose. Examples of “multilumen catheters” include central venous catheters having multiple lumens, midline catheters having multiple lumens, multiple catheters configured or emplaced such that their lumens are in proximity to each other, and, in the case of indwelling analyte sensors, a catheter with a lumen for infusion and an indwelling sensor spaced apart from the infusion lumen. For blood withdrawal, anti-cross contamination controls can prevent the entrainment of blood which might be contaminated with feeding fluids or medications that are administered through other lumens within the catheter and in proximity of the blood sampling port. Cross contamination can occur under various situations, and is known to occur when the patient is connected to a ventilator. The ventilator cyclically raises the intra-thoracic pressure and diminishes blood flow rate in the central veins returning to the heart. The diminished flow can increase the chances for cross-contamination when additional lumens are introducing fluids during a draw sample.

Claims

1. ) A method of withdrawing a blood sample from a withdrawal catheter port, wherein an infusate is infused through an infusion catheter port, comprising:

a) Determining patient conditions related to blood flow or pressure that are likely to lead to contamination of the withdrawn blood sample with the infusate, wherein the withdrawal port is distal from the heart relative to the infusion port;

b) Withdrawing a sample from the withdrawal port under withdrawal conditions determined in part from the patient conditions.

2. ) A method as in claim 1, wherein the patient conditions comprise a change in thoracic pressure.

3. ) A method as in claim 1, wherein withdrawing a sample comprises withdrawing a sample at a flow rate less than a flow rate determined from the patient conditions as likely to result in significant contamination of the sample with the infusate.

4. ) A method as in claim 1, wherein withdrawing a sample comprises withdrawing a sample at a withdrawal flow rate and controlling at least one of:

(a) the infusion rate and (b) the withdrawal rate;

such that the combination of the withdrawal rate and the infusion rates is not likely to result in significant contamination of the sample with infusate.

5. ) A method as in claim 1, wherein the patient conditions comprise a pressure difference between the infusion port and the withdrawal port.

6. ) A method as in claim 5, wherein withdrawing a sample comprises withdrawing a sample at a flow rate that is dependent on the pressure difference.

7. ) A method as in claim 5, wherein determining a pressure difference comprises determining a pressure near the infusion port, near the withdrawal port, or both.

8. ) A method as in claim 1, wherein the patient is subject to mechanical ventilation and wherein the patient conditions comprise pressure in the airway of the ventilator.

9. ) A method as in claim 1, wherein the patient is subject to mechanical ventilation, and wherein withdrawing a sample comprises withdrawing a sample at a flow rate that is dependent on the state of ventilator cycles.

10. ) A method as in claim 9, wherein the rate is substantially zero during the start of lung inflation and a flow rate greater than zero during lung deflation.

27. ) A method of measuring a target analyte in a patient'"'"'s blood, comprising withdrawing a sample of the patient'"'"'s blood according to the method of claim 1, and measuring the target analyte in the withdrawn sample.

28. ) A method as in claim 27, wherein measuring the target analyte comprises measuring the response of the blood sample to incident light, and determining the concentration of the target analyte from the response.

29. ) A method as in claim 27, wherein measuring the target analyte comprises separating a portion of the blood from the blood sample, and measuring the concentration of the target analyte in the separated portion.

11. ) A method of withdrawing a blood sample from a withdrawal port of a multilumen catheter that is distal relative the heart in relation to an infusion port through which a substance is being infused into the patient, the method comprising withdrawing the sample at a flow rate that is dependent on patient conditions.

12. ) A method as in claim 11, wherein the sample contains substantially no infusate.

13. ) A method as in claim 11, wherein the patient is subject to mechanical ventilation, and wherein the patient conditions comprise the ventilator cycle.

14. ) A method as in claim 11, wherein the patient conditions comprise thoracic pressure.

15. ) A method as in claim 11, wherein the patent conditions comprise abdominal pressure.

16. ) A method as in claim 11, wherein the patient conditions comprise intravascular pressure.

17. ) A method as in claim 11, wherein the patient conditions comprise electrical activity of the heart.

18. ) A method as in claim 11, wherein the patient conditions comprise conditions that lead to stagnant or retrograde flow between the withdrawal port and the infusion port.

30. ) A method of measuring a target analyte in a patient'"'"'s blood, comprising withdrawing a sample of the patient'"'"'s blood according to the method of claim 11, and measuring the target analyte in the withdrawn sample.

31. ) A method as in claim 30, wherein measuring the target analyte comprises measuring the response of the sample to incident light, and determining the concentration of the target analyte from the response.

32. ) A method as in claim 30, wherein measuring the target analyte comprises separating a portion of the blood from the blood sample, and measuring the concentration of the target analyte in the separated portion.

19. ) An apparatus for withdrawing a blood sample from a withdrawal port of a catheter that is proximal relative to a infusion port through which an infusate is infused into a patient, comprising:

a) A blood removal subsystem adapted to be attached to the withdrawal port of a central venous catheter;

b) A sensor susbsystem adapted to sense patient conditions;

c) A withdrawal controller adapted to control the blood removal subsystem to withdraw blood from the central venous catheter at a rate that is dependent on the patient conditions.

20. ) An apparatus as in claim 19, wherein the sample contains substantially no infusate.

21. ) An apparatus as in claim 19, wherein the patient is subject to mechanical ventilation, and wherein the patient conditions comprise the ventilator cycle.

22. ) An apparatus as in claim 19, wherein the patient conditions comprise thoracic pressure.

23. ) An apparatus as in claim 19, wherein the patent conditions comprise abdominal pressure.

24. ) An apparatus as in claim 19, wherein the patient conditions comprise intravascular pressure.

25. ) An apparatus as in claim 19, wherein the patient conditions comprise electrical activity of the heart.

26. ) An apparatus as in claim 19, wherein the patient conditions comprise conditions that lead to stagnant or retrograde flow between the withdrawal port and the infusion port.

33. ) A method of withdrawing a blood sample from a multilumen catheter, wherein an infusate is infused through an infusion port in the catheter, comprising:

a) Withdrawing a sample from a withdrawal port distal from the heart relative to the infusion port;

b) Determining patient conditions related to blood flow that is likely to lead to contamination with infusate of a sample drawn from a withdrawal port in the catheter;

c) If the patient conditions indicate that contamination is likely, then identifying the sample as contaminated.

34. ) A method as in claim 33, wherein identifying the sample as contaminated comprises separating the contaminated sample from uncontaminated samples.