EP0921842A1 - Process for monitoring patients with chronic congestive heart failure - Google Patents
Process for monitoring patients with chronic congestive heart failureInfo
- Publication number
- EP0921842A1 EP0921842A1 EP97922343A EP97922343A EP0921842A1 EP 0921842 A1 EP0921842 A1 EP 0921842A1 EP 97922343 A EP97922343 A EP 97922343A EP 97922343 A EP97922343 A EP 97922343A EP 0921842 A1 EP0921842 A1 EP 0921842A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- calculated
- chf
- ecw
- values
- patient
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
Classifications
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61N—ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY
- A61N1/00—Electrotherapy; Circuits therefor
- A61N1/02—Details
- A61N1/08—Arrangements or circuits for monitoring, protecting, controlling or indicating
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B5/00—Measuring for diagnostic purposes; Identification of persons
- A61B5/05—Detecting, measuring or recording for diagnosis by means of electric currents or magnetic fields; Measuring using microwaves or radio waves
- A61B5/053—Measuring electrical impedance or conductance of a portion of the body
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61N—ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY
- A61N1/00—Electrotherapy; Circuits therefor
- A61N1/18—Applying electric currents by contact electrodes
- A61N1/32—Applying electric currents by contact electrodes alternating or intermittent currents
- A61N1/36—Applying electric currents by contact electrodes alternating or intermittent currents for stimulation
- A61N1/362—Heart stimulators
- A61N1/3627—Heart stimulators for treating a mechanical deficiency of the heart, e.g. congestive heart failure or cardiomyopathy
Definitions
- Congestive heart failure results when the heart is unable to contract with sufficient vigor to meet the body's need for oxygen.
- CHF Congestive heart failure
- autoregulatory mechanisms allow the filling pressure in the ventricles to increase, thus elongating myocardial fibers at the start of systole and increasing the strength of contraction.
- left and/or right filling pressures exceed approximately 15 mm Hg, blood components are forced out of the vasculature and into the interstitium, resulting in pulmonary edema (left heart failure) and/or peripheral edema and ascites (right heart failure). The end results is severe incapacitation and possibly death.
- Lukaski & Bolonchuk have derived relationships between the components of the body's electrical impedance at either 50 kHz or 1000 Hz and either total body water or extracellular fluid. See Lukaski, et al., Estimation of Body Fluid Volumes Using Tetrapolar Bioelectrical Impedance Measurements. Aviation Space and Environmental Medicine; 1988; 59: 1163-1169.
- the present invention resides in an "early warning" monitoring system for determining changes in the status of patients with chronic congestive heart failure (CHF), with the goal of intervening before the onset of acute congestive heart failure.
- a process for monitoring patients with chronic congestive heart failure comprises the steps of applying electrodes to two points on the body, passing a current at one or more high frequencies between the electrodes, and then measuring the current (I) and voltage (V).
- Congestive heart failure (CHF) indicia values are calculated based on the measured current (I) and voltage
- the process comprises the steps of applying the electrodes to two limbs of a patient and then passing a i o high frequency current between the electrodes.
- Current (I), voltage (V) and phase angle (+) are measured, and then congestive heart failure (CHF) indicia values, including resistance (R) and reactance (Z c ), are calculated.
- CHF indicia values are then compared with baseline values, and intervention is initiated when the differences between the calculated CHF
- the process is repeated at an interval determined by whether or not intervention was required.
- the calculated CHF indicia values may include, in addition, impedance (Z).
- indicia values of resistance (R), reactance (Z c ) or impedance (Z), is an indicator of the need to initiate intervention.
- the tolerances from baseline values for the calculated CHF indicia values are on the order of five percent (5%) for resistance (R) and impedance (Z), ten percent (10%) for reactance (Z c ), and twenty percent (20%) for phase angle (f).
- the calculated CHF indicia values may also include total body water (TBW) and extracellular water (ECW).
- TW total body water
- ECW extracellular water
- the tolerances from baseline values are on the order of five percent (5%) for total body water (TBW) and extracellular water (ECW).
- Total body water may be calculated utilizing the formula:
- Extracellular water may be calculated utilizing the formula:
- the calculated CHF indicia values may further include a figure of merit which is indicative of the hydration status of the patient.
- the figure of merit may be derived from the ratio of extracellular water (ECW) over fat-free mass (FFM).
- Fat-free mass (FFM) may be calculated utilizing the formula:
- FFM - 15.26 - .775(Ht 2 /R) + .146 Wt + .185 Z c . Intervention is indicated when the ratio of extracellular water (ECW) to fat-free mass (FFM) is greater than approximately 0.30. Moreover, an increase in the figure of merit on the order of one percent (1 %) is an additional indicator of the need to initiate intervention.
- FIGURE 1 is the first of a two-part flow chart illustrating a process for monitoring patients with chronic congestive heart failure embodying the present invention.
- FIGURE 2 is the second of the two-part flow chart illustrating the process of the present invention.
- the present invention is concerned with a novel process for monitoring patients with congestive heart failure, generally indicated in FIGS. 1 and 2 by the reference number 10.
- the process 10 comprises, generally, the steps of applying electrodes to two points on the body of a patient and, while passing a current at one or more high frequencies between the electrodes, measuring the current (I) and voltage (V).
- Congestive heart failure (CHF) indicia values are then calculated based on the measured current (I) and voltage (V), which are compared with baseline values to determine if differences therebetween are within established tolerances. If those differences are outside of the established tolerances, intervention is initiated in accordance with sound medical practice.
- the process 10 of the present invention provides an "early warning" monitoring system for determining changes in the status of patients with chronic congestive heart failure with the goal of intervening before the onset of acute CHF.
- the process 10 of the present invention involves the tracking of total body impedance (Z), resistance (R), reactance (Z c ) and phase angle ( ⁇ r) in an abulatory patient with chronic congestive heart failure (CHF), and uses the decrease of any or all of these "indicia values" as predictors of the onset of acute CHF.
- the measurement can be made using a commercial device, such as that manufactured by RJL Systems of Clinton Twp., Ml, to measure body composition, or a similar device designed for this purpose.
- Significant intra-patient changes over time in the values of these parameters would be viewed as indicators of a deteriorating physical condition.
- the electrodes may be placed on any two points on the body, but preferably are positioned on either the ipsilateral wrist and ankle or on the contralateral wrist and ankle as described in Subramanyan, et al., Total Body Water in Congestive Heart Failure. Jour. Asso. Phys. Ind., Vol. 28, September,
- the process 10 of the present invention also includes utilizing the techniques described above applied to separate portions of the body of the patient to separately track peripheral and pulmonary edema. For example, measuring and tracking ankle-to-ankle impedance (Z) and its components would highlight changes in peripheral fluid, primarily indicative of right heart failure. Wrist-to-wrist impedance (Z) components would be more indicative of changes in lung fluid and left heart failure. Changes in any of these component impedance values would be used as an indicator of instability and suggest changes in therapeutic regimen.
- combining estimates 5 of total and extracellular water with estimates of body cell mass into a "figure of merit" indicative of the hydration status of the patient may be advantageously accomplished in accordance with the process 10 of the present invention.
- Changes in the "figure of merit” would be used as an indicator of worsening condition of the CHF patient.
- Typical figures of merit o would include the ratio of extracellular fluid (ECW)/fat-free mass (FFM), or the ratio of extracellular water (ECW)/total body weight.
- An increases in the figure of merit of approximately one percent (1%) would be used as an indicator of worsening condition.
- certain figures of merit, per se, rather than their change may be utilized as an indicator of congestive heart failure. For 5 example, when the ratio of extracellular water (ECW)/fat-free mass (FFM) is greater than approximately 0.30, it may be assumed that the patient is in congestive heart failure.
- the process 10 begins by applying clinical criteria to evaluate the risk of acute heart failure (block 12).
- 0 Factors to be evaluated are the patient's history of hospitalization for congestive heart failure (CHF), left ventricular ejection fraction (EF - the fraction of the left ventricle that is emptied in each cardiac contraction), and typical signs of CHF including neck vein distention, shortness of breath and swelling of the extremities.
- CHF congestive heart failure
- EF left ventricular ejection fraction
- typical signs of CHF including neck vein distention, shortness of breath and swelling of the extremities.
- High risk patients are those who have been hospitalized for CHF within the last three months, those who have been hospitalized for CHF within the last year and show new neck vein distention, those who have shortness of breath at rest or with minimal exertion, and/or those with an ejection fraction (EF) less than forty percent, for example. If the patient is not classified as a high risk, the physician may reevaluate the diagnosis as appropriate, for example, every three months or so (block 16).
- the bioelectric impedance analysis of the present invention is conducted to enable the health care provider to determine the patient's congestive heart failure (CHF) indicia values for purposes of comparing those values with baseline values established when the patient is in a known stable condition (block 18).
- CHF congestive heart failure
- two electrodes are attached to each of two limbs (block 20).
- the two more distal electrodes i.e., hand and foot
- the two more proximal electrodes i.e., wrist and ankle
- V voltage
- the electrodes have sufficient surface area so that the contact impedance is very low compared to the impedance (Z) of the body (i.e., «500 ⁇ )
- a single electrode on each of the two limbs can be used for both current injection and voltage measurement.
- Any pair of limbs may be used (right arm to left leg, right arm to left arm, etc.), or multiple pairs can be used and results calculated pair-by-pair.
- the electrodes are attached to the lower left extremity and the upper right extremity.
- a high frequency current is passed between the electrodes (block 22).
- a typical (preferred) current is 800 ⁇ amp at 50 kHz.
- a current of up to 5 ma could be used as well as any single frequency from 10 kHz to 100 kHz.
- the current (I) is measured (block 24) as well as the voltage (V) and phase angle ( ⁇ ) between the measured current (I) and voltage (V) (block 26).
- the voltage (V) and current (I) can be measured with any conventional technique, analog or digital.
- the delay between voltage and current in zero crossing (current lags voltage) bears the same relation to the waveform period as the phase angle ( ⁇ ) does to 360°.
- phase angle (+ ⁇ ) 360 (t/T), where tange is the time by which current (I) lags voltage (V), and (T) is the waveform period (the inverse of frequency).
- congestive heart failure (CHF) indicia values may then be calculated (blocks 28, 30 and 32).
- the first indicia values calculated include impedance (Z), resistance (R) and reactance (Z c ).
- Impedance (Z) is the rms voltage divided rms current.
- the patient's total body water (TBW), extracellular water (ECW) and fat-free mass (FFM) may also be calculated to provide CHF indicia values.
- Total body water (TBW) and extracellular water (ECW) can be calculated from the formulas of Lukaski H.C. & Bolonchuk W.W. Estimation of Bodv Fluid Volumes Using Tetrapolar Bioelectrical 5 Impedance Measurements. Aviation Space and Environmental Medicine,
- Fat-free mass can be calculated from the formula provided in Huges, V.A., and Evans W.J. Assessment of Fat-Free Mass in an Older Population Using Bioelectric Impedance. Fed Proc 1987; 46 (Abstract), as follows:
- Block 32 illustrates deriving a "figure of merit” from the ratio of extracellular water (ECW) over fat-free mass (FFM).
- the baseline values are preferably measured when the patient is in a known, stable condition, such as when discharged from the hospital and/or entered into the monitoring program. If it is the baseline values that are being established (block 34), they are stored (block 36) for further reference.
- the stored baseline values will typically include the weight (Wt) of the patient, the calculated impedance (Z), resistance (R), reactance (Z c ), phase angle (*), total body water (TBW), extracellular water (ECW), fat-free mass (FFM), and the ratio of extracellular water to fat-free mass (ECW/FFM).
- a decrease in the phase angle ( ⁇ ) or any of the calculated CHF indicia values of resistance (R), reactance (ZJ or impedance (Z), is an indicator of the need to initiate intervention.
- the tolerances from baseline values are on the order of five percent (5%) for resistance (R) and impedance (Z), ten percent (10%) for reactance (Z c ), and twenty percent (20%) for phase angle (+).
- An increase in the calculated total body water (TBW) or extracellular water (ECW) is an indicator of the need to initiate intervention.
- the tolerances from baseline values for such calculated CHF indicia values are on the order of five percent
- the preferred delay before repeating the measurements is one to two weeks.
- Interventions are based on medical judgment and form no part of the present invention. They might include counseling to reduce the amount of salt in the diet or reduce activity.
- diuretics and/or angiotensin converting enzyme inhibitors could be increased.
- intravenous diuretics could be started as could intravenous agents to increase the pumping action of the heart (inotropes such as dobutamine), or the patient could be advised to seek hospitalization.
Abstract
Description
Claims
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US1601596P | 1996-04-23 | 1996-04-23 | |
US16015P | 1996-04-23 | ||
PCT/US1997/006466 WO1997039792A1 (en) | 1996-04-23 | 1997-04-22 | Process for monitoring patients with chronic congestive heart failure |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0921842A1 true EP0921842A1 (en) | 1999-06-16 |
EP0921842A4 EP0921842A4 (en) | 1999-12-15 |
Family
ID=21774907
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP97922343A Withdrawn EP0921842A4 (en) | 1996-04-23 | 1997-04-22 | Process for monitoring patients with chronic congestive heart failure |
Country Status (5)
Country | Link |
---|---|
EP (1) | EP0921842A4 (en) |
JP (1) | JP3325273B2 (en) |
AU (1) | AU2804397A (en) |
CA (1) | CA2251718C (en) |
WO (1) | WO1997039792A1 (en) |
Families Citing this family (21)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US7134996B2 (en) | 1999-06-03 | 2006-11-14 | Cardiac Intelligence Corporation | System and method for collection and analysis of patient information for automated remote patient care |
US6270457B1 (en) | 1999-06-03 | 2001-08-07 | Cardiac Intelligence Corp. | System and method for automated collection and analysis of regularly retrieved patient information for remote patient care |
US6607485B2 (en) | 1999-06-03 | 2003-08-19 | Cardiac Intelligence Corporation | Computer readable storage medium containing code for automated collection and analysis of patient information retrieved from an implantable medical device for remote patient care |
US6312378B1 (en) | 1999-06-03 | 2001-11-06 | Cardiac Intelligence Corporation | System and method for automated collection and analysis of patient information retrieved from an implantable medical device for remote patient care |
CA2314517A1 (en) | 1999-07-26 | 2001-01-26 | Gust H. Bardy | System and method for determining a reference baseline of individual patient status for use in an automated collection and analysis patient care system |
CA2314513A1 (en) | 1999-07-26 | 2001-01-26 | Gust H. Bardy | System and method for providing normalized voice feedback from an individual patient in an automated collection and analysis patient care system |
US6221011B1 (en) | 1999-07-26 | 2001-04-24 | Cardiac Intelligence Corporation | System and method for determining a reference baseline of individual patient status for use in an automated collection and analysis patient care system |
US7127290B2 (en) * | 1999-10-01 | 2006-10-24 | Cardiac Pacemakers, Inc. | Cardiac rhythm management systems and methods predicting congestive heart failure status |
US6440066B1 (en) | 1999-11-16 | 2002-08-27 | Cardiac Intelligence Corporation | Automated collection and analysis patient care system and method for ordering and prioritizing multiple health disorders to identify an index disorder |
US8369937B2 (en) | 1999-11-16 | 2013-02-05 | Cardiac Pacemakers, Inc. | System and method for prioritizing medical conditions |
US6411840B1 (en) | 1999-11-16 | 2002-06-25 | Cardiac Intelligence Corporation | Automated collection and analysis patient care system and method for diagnosing and monitoring the outcomes of atrial fibrillation |
US6336903B1 (en) | 1999-11-16 | 2002-01-08 | Cardiac Intelligence Corp. | Automated collection and analysis patient care system and method for diagnosing and monitoring congestive heart failure and outcomes thereof |
US6368284B1 (en) | 1999-11-16 | 2002-04-09 | Cardiac Intelligence Corporation | Automated collection and analysis patient care system and method for diagnosing and monitoring myocardial ischemia and outcomes thereof |
US8025624B2 (en) | 2004-02-19 | 2011-09-27 | Cardiac Pacemakers, Inc. | System and method for assessing cardiac performance through cardiac vibration monitoring |
US7386345B2 (en) | 2005-01-27 | 2008-06-10 | Cardiac Pacemakers, Inc. | Apparatus and method for temporary treatment of acute heart failure decompensation |
CN102159132B (en) * | 2008-09-22 | 2015-11-25 | 奇塔医疗公司 | For determining the system and method for blood flow |
US9999352B2 (en) | 2013-09-27 | 2018-06-19 | General Electric Company | System and method for determining a hydration level of a tissue region |
WO2017139839A1 (en) * | 2016-02-16 | 2017-08-24 | Impedimed Limited | Heart failure indicator |
KR101823496B1 (en) | 2016-08-22 | 2018-01-31 | 조선대학교산학협력단 | Wearable device for measuring edema index and method of measuring edema index using thereof |
JP7204740B2 (en) * | 2018-03-26 | 2023-01-16 | テルモ株式会社 | Diagnosis support system, diagnosis support method, and diagnosis support program |
KR102484225B1 (en) * | 2020-10-15 | 2023-01-03 | 계명대학교 산학협력단 | A patch type impedance measurement device and method |
Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5334222A (en) * | 1992-11-03 | 1994-08-02 | Cardiac Pacemakers, Inc. | Cardiac stimulating apparatus and method for heart failure therapy |
Family Cites Families (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4899758A (en) * | 1986-01-31 | 1990-02-13 | Regents Of The University Of Minnesota | Method and apparatus for monitoring and diagnosing hypertension and congestive heart failure |
US5560368A (en) * | 1994-11-15 | 1996-10-01 | Berger; Ronald D. | Methodology for automated QT variability measurement |
-
1997
- 1997-04-22 WO PCT/US1997/006466 patent/WO1997039792A1/en not_active Application Discontinuation
- 1997-04-22 EP EP97922343A patent/EP0921842A4/en not_active Withdrawn
- 1997-04-22 AU AU28043/97A patent/AU2804397A/en not_active Abandoned
- 1997-04-22 CA CA002251718A patent/CA2251718C/en not_active Expired - Lifetime
- 1997-04-22 JP JP53819597A patent/JP3325273B2/en not_active Expired - Lifetime
Patent Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5334222A (en) * | 1992-11-03 | 1994-08-02 | Cardiac Pacemakers, Inc. | Cardiac stimulating apparatus and method for heart failure therapy |
Non-Patent Citations (1)
Title |
---|
See also references of WO9739792A1 * |
Also Published As
Publication number | Publication date |
---|---|
AU2804397A (en) | 1997-11-12 |
CA2251718C (en) | 2001-07-10 |
EP0921842A4 (en) | 1999-12-15 |
CA2251718A1 (en) | 1997-10-30 |
JP3325273B2 (en) | 2002-09-17 |
WO1997039792A1 (en) | 1997-10-30 |
JP2000510005A (en) | 2000-08-08 |
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