Determining the hydration status of a patient

• US 7,133,716 B2
• Filed: 12/12/2001
• Issued: 11/07/2006
• Est. Priority Date: 12/12/2001
• Status: Expired due to Fees

• Current Assignee: Fresenius Medical Care Deutschland GmbH (Fresenius SE & Co. KGaA)
• Original Assignee: Fresenius Medical Care Deutschland GmbH (Fresenius SE & Co. KGaA)
• Inventors: Chamney, Paul, Kraemer, Matthias
• Primary Examiner(s): Hindenburg, Max F.
• Assistant Examiner(s): Rogers, Kristin D
• Application Number:
  US10/497,172
• Publication Number:
  US 20050039763A1
• Time in Patent Office: 1,791 Days
• Field of Search: 600/547, 600/506, 600/399, 600/536, 600/442
• US Class Current: 600/547
• CPC Class Codes: A61B 5/0537 Measuring body composition by impedance, e.g. tissue hydration or fat content

Abstract

A device and method are provided for determining the volume ECV_hydr(t) of a body compartment of a patient at a time t by conducting measurements at the time t of the patient to determine at least one anthropometric measure X(t), the extracellular water volume ECV(t), and the intracellular water volume ICV (t) of the patient. The extracellular water volume ECV_basic(t) of a first compartment with weight W_basic(t) of the patient at the time t is derived by using X (t), the extracellular water volume ECV_sec(t) of a second compartment of the patient at the time t is derived by using ICV (t), and ECV_hydr(t) as the extracellular water volume of a third compartment of the patient is derived with weight W_hydr(t). The extracellular volume ECV_hydr(t) is a measure for the hydration status of the patient.

Claims

1. A method for determining the volume of a body compartment ECV_hydrhydr(t) of a patient at a time t in order to manage a hydration level of said patient comprising the steps of:

determining at least one anthropometric measure X(t) of the patient at the time t;

determining the extracellular water volume ECV(t) of the patient at the time;

determining the intracellular water volume ICV(t) of the patient at the time t;

deriving the extracellular water volume ECV_basic(t) of a first compartment with weight W_basic(t) of the patient at the time t by using X(t);

deriving the extracellular water volume ECV_sec(t) of a second compartment with weight W_sec(t) of the patient at the time t by using ICV(t);

deriving the volume ECV_hydrhydr(t) as the extracellular water volume of a third compartment of the patient with weight W_hydr(t) by using the equation

ECV_hydr(t)=ECV(t)−

ECV_basic(t)−

ECV_sec(t); and

managing the hydration level of said patient using said derived volume ECV_hydr(t).

2. The method according to claim 1 wherein the second compartment represents the muscle tissue with weight W_muscle(t) and the extracellular water volume ECV_muscle(t).

3. The method according to claim 1 wherein the intracellular water volume ICV_basic(t) of the first compartment is also derived from X(t) and that ICV_basic(t) is also used to derive ECV_sec(t).

4. The method according to claim 1 wherein the weight W(t) of the patient at time t is determined and that the extracellular water volume ECV_basic(t) and/or the intracellular water volume ICV_basic(t) of the first compartment are derived by using X(t) and W(t).

5. The method according to claim 1 wherein at the extracellular and/or intracellular water volumes ECV_basic(t) and ICV_basic(t) of the first compartment are derived by also using ICV(t).

6. The method according to claim 1 wherein the at least one anthropometric measure X(t) is the height H(t) of the patient at the time t.

7. The method according to claim 1 wherein ECV(t) and ICV(t) are derived from a bioimpedance measurement.

8. The method according to claim 1 wherein ECV_basic(t) is derived from various subcompartments by the following equation:

${\mathrm{ECV}}_{\mathrm{basic}}<br><br>\left(t\right)=\underset{i}{\overset{}{\sum <br><br>}}<br><br><br><br>{\mathrm{ECV}}_{\mathrm{basic},i}<br><br>\left(t\right),$

where ECV_basic,i(t) is the ECV of the i^th subcompartment of the first compartment at the time t.

9. The method according to claim 1 wherein at least one of the i ECV_basic,i(t) values is derived as proportional part of the weight W_basic,i(t) of the i^th subcompartment, i.e.

ECV_basic,i(t)=λ

_ECV,iW_basic,i(t),

where λ

_ECV,i is the corresponding proportionality constant.

10. The method according to claim 1 wherein ICV_basic(t) is derived from various subcompartments by the following equation:

${\mathrm{ICV}}_{\mathrm{basic}}<br><br>\left(t\right)=\underset{i}{\overset{}{\sum <br><br>}}<br><br><br><br>{\mathrm{ICV}}_{\mathrm{basic},i}<br><br>\left(t\right),$

where ICV_basic,i(t) is the ICV of the i^th subcompartment of the first compartment at the time t.

11. The method according to claim 10 wherein at least one of the i ICV_basic,i(t) values is derived as proportional part of the weight W_baslc,i(t) of the i^th subcompartment, i.e.

ICV_basic,i(t)=λ

_ICV,iW_basic,i(t),

where λ

_ICV,i is the corresponding proportionality constant.

12. The method according to claim 8 wherein the subcompartments comprise four subcompartments representing the skeleton (ECV_{basic,sceleton}, ICV_{basic,sceleton}, W_{basic,skeleton}), organs (ECV_basic,organ, ICV_basic,organ, W_basic,organ), blood (ECV_basic,blood, ICV_basic,blood, W_basic,blood) and skin (ECV_basic,skin, ICV_basic,skin, W_basic,skin).

13. The method according to claim 6 wherein an average weight W_av(H(t)) is derived from the measured height H(t) of a patient and a previously established H against W_av(H) relation for a reference population and that at least one of the subcompartmental weights W_basc,i is derived by

W_basic,i(t)=k_iW_av(H(t)),

where k_i is the corresponding proportionality constant.

14. The method according to claim 12 wherein the relation for W_basic,i(t) is used for the skeleton and the organ subcompartment.

15. The method according to claim 12 wherein the haematocrit Hct(t) of the patient at the time t is determined and that Hct(t) is used to claim derive W_basic,blood(t).

16. The method according to claim 12 wherein the body surface area index (BSA(t)) of the patient at the time t is determined and that BSA(t) is used to derive W_basic,skin(t).

17. The method according to claim 4 wherein the masses W_basic(t), W_sec(t) and W_hydr(t) of the first, second and third compartments are derived and that the mass W_fat(t) of a fourth compartment of the patient at the time t is derived by the following formulae:

W_fat(t)=W(t)−

W_basic(t)−

W_sec(t)−

W_hydr(t).

18. A method for determining a muscle weight W_muscle(t) of a patient at a time t comprising the steps of:

determining at least one anthropometric measure X(t) of the patient at the time t;

determining the intracellular water volume ICV(t) of the patient at the time t;

deriving the intracellular water volume ICV_basic(t) of a first compartment with weight W_basic(t) of the patient at the time t by using X(t);

deriving the muscle weight W_muscle(t) as the weight of a second compartment of the patient by using ICV_basic(t) and ICV(t); and

assessing a nutrition and fitness status of said patient using the derived muscle weight W_muscle(t) and using said status to manage care of said patient.

19. The method according to claim 18 wherein W_muscle(t) is derived by the relation

$W_{\mathrm{muscle}}$

( t ) = ( ICV ⁡

( t ) - ICV basic ⁡

( t ) ) ⁢

( 1 + γ

) λ

TBW_muscle ,

where γ

is the ratio between the extracellular water to intracellular water volume in the second compartment and λ

<sub>TBW—

muscle</sub> is the fraction of water per unit mass in the second compartment.

20. The method according to claim 18 wherein the weight W_basic(t) of the first compartment of the patient at the time t is also derived by using X(t).

21. The method according to claim 20 wherein a lean body mass LBM(t) of the patient at the time t is derived by using the equation

LBM(t)=W_basic(t)+W_muscle(t).

22. The method according to claim 18 wherein the first compartment comprises the skeleton, organs, blood and skin of the patient.

23. A device for determining the volume of a body compartment ECV_hydr(t) of a patient at a time t by determining at least one anthropometric measure X(t) of the patient at the time t, determining the extracellular water volume ECV(t) of the patient at the time t, determininq the intracellular water volume ICV(t) of the patient at the time t, deriving the extracellular water volume ECV_basic(t) of a first compartment with weight W_basc(t) of the patient at the time t by using X(t), deriving the extracellular water volume ECV_sec(t) of a second compartment with weight W_sec(t) of the patient at the time t by using ICV(t), and deriving the volume ECV_hydr(t) as the extracellular water volume of a third compartment of the patient with weight W_hydr(t) by using the equation,

ECV_hydr(t)=ECV_basic(t)−

ECV_sec(t), the device comprising;

a microprocessor unit which includes a microprocessor program storage unit;

an input unit to claim enable entering values of ECV(t), ICV(t) and X(t);

a computer storage unit for storing the ECV(t), ICV(t) and X(t) values; and

said microprocessor program storage unit including a program for deriving the extracellular water volume ECV_hydr(t) by deriving the extracellular water volume ECV_basic(t) of the first compartment with weight W_basic(t) of the patient at the time t by using the value(s) of X(t), by deriving the extracellular water volume ECV_sec(t) of the second compartment with weight W_sec(t) of the patient at the time t by using the value of ICV(t), and by deriving the volume ECV_hydr(t) as the extracellular water volume of the third compartment of the patient with weight W_hydr(t) by using the equation

ECV_hydr(t)=ECV(t)−

ECV_basic(t)−

ECV_sec(t).

24. The device according to claim 23 wherein said device further comprises means for determining the ECV(t) and ICV(t) values.

25. The device according to claim 23 wherein said device further comprises means for determining the values of the at least one anthropometric measure X(t) and/or the weight W(t) of the patient at the time t.

26. The device according to claim 24 wherein said means for determining the ECV(t) and ICV(t) values is a bioimpedance measurement device.

27. The device according to claim 23 wherein the input unit is a manual user interface.

28. The device according to claim 23 wherein the input unit includes an interface for means for determining the ECV(t) and ICV(t) values and/or means for determining the X(t) and/or W(t) values.

29. The device according to claim 23 further comprising an output unit that is linked to claim the microprocessor unit for outputting the derived ECV_hydr(t) value.

30. The device according to claim 23 wherein the input unit is enabled to claim receive a value for the haematocrit Hct(t) of the blood of the patient at the time t and the computer storage unit is enabled to claim store said Hct(t) value and the program stored in the microprocessor program storage unit corrects the weight of the first compartment W_basic(t) for the value of the haematocrit.

31. A device for determining a muscle weight W_muscle(t) of a patient at a time t by determining at least one anthropometric measure X(t) of the patient at the time t, determining the intracellular water volume ICV(t) of the patient at the time t, deriving the intracellular water volume ICV_basic(t) of a first compartment with weight W_basic(t) of the patient at the time t by using X(t), and deriving the muscle weight W_muscle(t) as the weight of a second compartment of the patient by using ICV_basic(t) and ICV(t), the device comprising:

a microprocessor unit including a microprocessor program storage unit;

an input unit to claim enable entering values of ICV(t) and X(t);

a computer storage unit for storing the ICV(t) and X(t) values; and

said microprocessor program storage unit including a program for deriving the muscle weight W_muscle(t) of the second compartment by deriving the intracellular water volume ICV_basic(t) of the first compartment with weight W_basic(t) of the patient at the time t by using the value(s) of X(t), and by deriving the weight W_muscle(t) of the second compartment of the patient at the time t by using ICV_basic(t) and ICV(t).

32. A microprocessor program storage medium having stored thereon a program for determining a muscle weight W_muscle(t) of a patient at a time t using at least one anthropometric measure X(t) and the intracellular water volume ICV(t) of the patient at the time t, said program on said storage medium deriving the intracellular water volume ICV_basic(t) of a first compartment with weight W_basic(t) of the patient at the time t by using X(t), and deriving the muscle weight W_muscle(t) as the weight of a second compartment of the patient by using ICV_basic(t) and ICV(t).

33. A microprocessor program storage medium having stored thereon a program for determining the volume of a body compartment ECV_hydr(t) of a patient at a time t using at least one anthropometric measure X(t), the extracellular water volume ECV(t) and the intracellular water volume ICV(t) of the patient at the time t, said program on said storage medium deriving the extracellular water volume ECV_basic(t) of a first compartment with weight W_basic(t) of the patient at the time t by using X(t), deriving the extracellular water volume ECV_sec(t) of a second compartment with weight W_sec(t) of the patient at the time t by using ICV(t), and deriving the volume ECV_hydr(t) as the extracellular water volume of a third compartment of the patient with weight W_hydr(t) by using the equation,

ECV_hydr(t)=ECV(t)−

ECV_basic(t)−

ECV_sec(t).

34. A method for determining the volume of a body compartment ECV_hydr(t) of a patient at a time t comprising the steps of:

conducting a measurement of the patient at the time t to determine at least one anthropometric measure X(t) of the patient;

conducting a measurement of the patient at the time (t) to determine the extracellular water volume ECV(t) of the patient;

conducting a measurement of the patient at the time t to determine the intracellular water volume ICV(t) of the patient;

deriving the extracellular water volume ECV_basic(t) of a first compartment with weight W_basic(t) of the patient at the time t by using X(t);

deriving the extracellular water volume ECV_hydrsec(t) of a second compartment with weight W_sec(t) of the patient at the time t by using ICV(t); and

deriving the volume ECV_hydr(t), which is a measure of hydration status of the patient, as the extracellular water volume of a third compartment of the patient with weight W_hydr(t) by using the equation

ECV_hydr(t)=ECV(t)−

ECV_basic(t)−

ECV_sec(t).

35. The method according to claim 34 wherein the second compartment represents the muscle tissue with weight W_muscle(t) and the extracellular water volume ECV_muscle(t).

36. The method according to claim 34 wherein the intracellular water volume ICV_basic(t) of the first compartment is also derived from X(t) and that ICV_basic(t) is also used to claim derive ECV_sec(t).

37. The method according to claim 34 wherein the weight W(t) of the patient at time t is determined and that the extracellular water volume ECV_basic(t) and/or the intracellular water volume ICV_basic(t) of the first compartment are derived by using X(t) and W(t).

38. The method according to claim 34 wherein at the extracellular and/or intracellular water volumes ECV_basic(t) and ICV_basic(t) of the first compartment are derived by also using ICV(t).

39. The method according to claim 34 wherein the at least one anthropometric measure X(t) is the height H(t) of the patient at the time t.

40. The method according to claim 34 wherein ECV(t) and ICV(t) are derived from a bioimpedance measurement.

41. The method according to claim 34 wherein ECV_(t) is derived from various subcompartments by the following equation:

${\mathrm{ECV}}_{\mathrm{basic}}<br><br>\left(t\right)=\underset{i}{\overset{}{\sum <br><br>}}<br><br><br><br>{\mathrm{ECV}}_{\mathrm{basic},i}<br><br>\left(t\right),$

where ECV_basic,i(t) is the ECV of the i^th subcompartment of the first compartment at the time t.

42. The method according to claim 34 wherein at least one of the i ECV_basic,i(t) values is derived as proportional part of the weight W_basic,i(t) of the ith subcompartment, i.e.

ECV_basic,i(t)=λ

_ECV,iW_basic,i(t),

where λ

ECV,i is the corresponding proportionality constant.

43. The method according to claim 34 wherein ICV_basic(t) is derived from various subcompartments by the following equation:

${\mathrm{ICV}}_{\mathrm{basic}}<br><br>\left(t\right)=\underset{i}{\overset{}{\sum <br><br>}}<br><br><br><br>{\mathrm{ICV}}_{\mathrm{basic},i}<br><br>\left(t\right),$

where ICV_basic,i(t) is the ICV of the i^th subcompartment of the first compartment at the time t.

44. The method according to claim 43 wherein at least one of the i ICV_basic,i(t) values is derived as proportional part of the weight W_basic,i(t) of the i^th subcompartment, i.e.

ECV_basic,i(t)=λ

_ICV,iW_basic,i(t),

where λ

_ICV,i is the corresponding proportionality constant.

45. The method according to claim 41 wherein the subcompartments comprise four subcompartments representing the skeleton (ECV_{basic,sceleton}, ICV_{basic,sceleton}, W_{basic,skeleton}), organs (ECV_basic,organ, ICV_basic,organ, W_basic,organ), blood (ECV_basic,blood, ICV_basic,blood, W_basic,blood) and skin (ECV_basic,skin, ICV_basic,skin, W_basic,skin).

46. The method according to claim 39 wherein an average weight W_av(H(t)) is derived from the measured height H(t) of a patient and a previously established H against W_av(H) relation for a reference population and that at least one of the subcompartmental weights W_basic,i is derived by

W_basic,i(t)=k_iW_av(H(t)),

where k_i is the corresponding proportionality constant.

47. The method according to claim 44 wherein the relation for W_basic,i(t) is used for the skeleton and the organ subcompartment.

48. The method according to claim 44 wherein the haematocrit Hct(t) of the patient at the time t is determined and that Hct(t) is used to claim derive W_basic,blood(t).

49. The method according to claim 45 wherein the body surface area index (BSA(t)) of the patient at the time t is determined and that BSA(t) is used to claim derive W_basic,skin(t).

50. The method according to claim 37 wherein the masses W_basic(t), W_sec(t) and W_hydr(t) of the first, second and third compartments are derived and that the mass W_fat(t) of a fourth compartment of the patient at the time t is derived by the following formulae:

W_fat(t)=W(t)−

W_basic(t)−

W_sec(t)−

W_hydr(t).

51. A method for determining a muscle weight W_muscle(t) of a patient at a time t comprising the steps of:

conducting a measurement of the patient at the time t to determine at least one anthropometric measure X(t) of the patient;

conducting a measurement of the patient at the time t to determine the intracellular water volume ICV(t) of the patient;

deriving the intracellular water volume ICV_basic(t) of a first compartment with weight W_basic(t) of the patient at the time t by using X(t); and

deriving the muscle weight W_muscle(t), which provides an assessment of fitness and training status of the patient, as the weight of a second compartment of the patient by using ICV_basic(t) and ICV(t).

52. The method according to claim 51 wherein W_muscle(t) is derived by the relation

$W_{\mathrm{muscle}}$

( t ) = ( ICV ⁡

( t ) - ICV basic ⁡

( t ) ) ⁢

( 1 + γ

) λ

TBW_muscle ,

where γ

is the ratio between the extracellular water to intracellular water volume in the second compartment and λ

TBW<sub>—

muscle</sub> is the fraction of water per unit mass in the second compartment.

53. The method according to claim 51 wherein the weight W_basic(t) of the first compartment of the patient at the time t is also derived by using X(t).

54. The method according to claim 53 wherein a lean body mass LBM(t) of the patient at the time t is derived by using the equation

LBM(t)=W_basic(t)+W_muscle(t).

55. The method according to claim 51 wherein the first compartment comprises the skeleton, organs, blood and skin of the patient.