U.S. patent application number 14/027208 was filed with the patent office on 2014-03-13 for diagnostic method and apparatus.
This patent application is currently assigned to FlowSense Ltd.. The applicant listed for this patent is FlowSense Ltd.. Invention is credited to Ilan PAZ, Natan PAZ.
Application Number | 20140073991 14/027208 |
Document ID | / |
Family ID | 39402077 |
Filed Date | 2014-03-13 |
United States Patent
Application |
20140073991 |
Kind Code |
A1 |
PAZ; Ilan ; et al. |
March 13, 2014 |
DIAGNOSTIC METHOD AND APPARATUS
Abstract
The present invention provides a diagnostic method comprising
continuously monitoring and transmitting urine output and urine
flow rates of a catheterized patient to means which correlate the
same with at least one of renal perfusion, renal function, fluid
status, polyuria, oleguria, hypoperfusion, hemorrhage shock and
GFR.
Inventors: |
PAZ; Ilan; (Gush Etzion,
IL) ; PAZ; Natan; (Gush Etzion, IL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
FlowSense Ltd. |
M.p. Misgav |
|
IL |
|
|
Assignee: |
FlowSense Ltd.
M.p. Misgav
IL
|
Family ID: |
39402077 |
Appl. No.: |
14/027208 |
Filed: |
September 15, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12514835 |
Aug 9, 2010 |
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PCT/IL2007/001375 |
Nov 8, 2007 |
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14027208 |
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Current U.S.
Class: |
600/581 ;
29/428 |
Current CPC
Class: |
A61B 5/4839 20130101;
A61B 5/208 20130101; A61B 5/20 20130101; Y10T 29/49826 20150115;
A61B 5/201 20130101; A61B 10/007 20130101; A61B 5/14507
20130101 |
Class at
Publication: |
600/581 ;
29/428 |
International
Class: |
A61B 5/20 20060101
A61B005/20; A61B 10/00 20060101 A61B010/00 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 14, 2006 |
IL |
179252 |
Nov 1, 2007 |
IL |
187080 |
Claims
1. A diagnostic method comprising continuously monitoring and
transmitting urine output and urine flow rates of a catheterized
patient to means which correlate the same with at least one of
renal perfusion, renal function, fluid status, polyuria, oleguria,
hypoperfusion, hemorrhage shock and GFR.
2. A diagnostic method according to claim 1, wherein said method
utilizes a low flow metering device.
3. A diagnostic method according to claim 1, further comprising
continuously monitoring and graphically representing in real minute
unit time fluctuations in renal flow and renal output.
4. A diagnostic method according to claim 1 for early prognosis of
a disease affiliated with abnormal body fluid status.
5. A diagnostic method according to claim 3 wherein said disease is
affiliated with hypoperfusion.
6. A diagnostic method according to claim 3 wherein said disease is
affiliated with hyperperfusion.
7. A diagnostic method according to claim 2 wherein said low flow
metering device incorporates a drop generator and a droplet
counter.
8. A diagnostic method according to claim 1 further comprising
providing alarm means.
9. A diagnostic method according to claim 1, comprising
continuously monitoring and transmitting urine flow rates per
minute units of a catheterized patient to means which correlate the
same with at least one of renal perfusion, renal function, fluid
status, polyuria, oleguria, hypoperfusion, hemorrhage shock and
GFR.
10. A diagnostic method according to claim 9, comprising
administering a diuretic to a catheterized patient and monitoring
and displaying the slope of urine output per minute after
administration thereof.
11. A diagnostic method according to claim 9, comprising
administering a predetermined amount of fluid to a catheterized
patient and monitoring and displaying the slope of urine output per
minute unit after administration thereof and observing a parameter
selected from the slope, the peak and the total time for the flow
of urine to return to steady state flow in order to determine the
state of the kidney.
12. A diagnostic method according to claim 1 for determining the
hemodynamic state of a patient comprising administering a bolus of
fluid to the patient and monitoring and displaying urine flow
reaction to said bolus to determine the state of hydration and
hemorrhagic shock.
13. The use of a low flow metering device for the manufacture of a
diagnostic system for continuous monitoring and measuring of urine
output and urine flow of a catheterized patient further comprising
linking the output of said device with means which correlate the
same with at least one of renal perfusion, renal function, fluid
status, polyuria, oleguria, hypoperfusion, hemorrhage shock and
GFR.
14. A system for management of the hemodynamic state and kidney
function of the body comprising a low flow metering device which
continuously monitors and measures urine output and urine flow of a
catheterized patient wherein the output of said device is linked to
monitoring means and displaying means which display the slope of
urine output and urine flow rates per minute units.
15. An apparatus for management of the hemodynamic state and kidney
function of the body comprising a low flow metering device which
continuous monitors and measures urine output and urine flow of a
catheterized patient wherein the output of said device is linked to
means for monitoring and displaying the slope of urine output and
urine flow rates per minute units.
16. An apparatus according to claim 15 further comprising means
which correlate the same with at least one of renal perfusion,
renal function, fluid status, polyuria, oleguria, hypoperfusion,
hemorrhage shock and GFR.
17. An apparatus according to claim 15 further comprising means
which continuously monitor and graphically represent, in real
minute unit time, fluctuations in renal flow and renal output.
18. An apparatus according to claim 15 which monitors and measures
urine output and urine flow of a catheterized patient after the
administration of a diuretic.
19. An apparatus according to claim 15 which monitors and measures
urine output and urine flow of a catheterized patient after the
administration of a bolus of fluid to a patient in a stable steady
state with a constant fluid input and output.
20. An apparatus for management of the hemodynamic state and kidney
function of the body comprising a low flow metering device which
continuously monitors and measures output and urine flow of a
catheterized patient wherein the output of said device is linked to
means which monitor and display the slope of urine output and urine
flow rates per minute units during surgery.
21. An apparatus for management of the hemodynamic state and kidney
function of the body comprising a low flow metering device which
continuously monitors and measures urine output and urine flow of a
catheterized patient, wherein the output of said device is linked
to means which monitor and display the slope of urine output and
urine flow rates per minute units after administration of a
nephrotoxic drug.
22. An apparatus for management of the hemodynamic state and kidney
function of the body comprising a low flow metering device for
which continuously monitors and measures urine output and urine
flow of a catheterized patient wherein the output of said device is
linked to means which monitor and display the slope of urine output
and urine flow rates per minute units during administration of a
nephrotoxic drug.
Description
[0001] The present invention relates to a diagnostic method
correlating urine output and urine flow for early prognosis of a
disease affiliated with abnormal body fluid status. The present
invention also provides an apparatus and system for management of
the hemodynamic state and kidney function of the body.
[0002] The field of the invention relates to management of a
patient's fluid, more specifically providing an indication of
"urine flow" such as an indication of renal perfusion, an
indication of Glomerular Filtration Rate (GFR), changes in
extracellular fluid, kidney function and urine irrigation problems,
etc.
[0003] One of the most troublesome of all problems in critically
ill patients is maintenance of adequate body fluid and proper
balance between fluid input and fluid output. To date, most
patients that are hospitalized in the Intensive Care Unit (ICU) are
monitored by continuous measurement of several hemodynamic
parameters, such as heart rate, invasive blood pressure
measurement, central venous pressure (CVP) and occasionally, wedge
pressure.
[0004] It is well known that one of the most important parameters
that reflect proper organ perfusion is the hourly urine output.
However, currently the tools and systems that are used are not
precise enough. One outcome of this is the high occurrence of acute
renal failure (ARF) in ICU's. This complication occurs in a
significant percentage of critically ill patients. The most common
underlying etiology is acute tubular necrosis, usually precipitated
by hypoperfusion and/or nephrotoxic agents. On the other hand,
overzealous use of fluid may result in fluid overload, pulmonary
edema and ARDS.
[0005] Since appropriate management of the fluid balance and kidney
function in the critically ill patient is essential it is an object
of the present invention to provide a new diagnostic method that
continuously monitors and measures urine output and urine flow and
correlates the same to provide real time warning with regard to
abnormal fluctuations and perfusion to all the organs of the body
and especially the kidneys.
[0006] Thus according to the present invention there is now
provided a diagnostic method comprising continuously monitoring and
transmitting urine output and urine flow rates of a catheterized
patient to means which correlate the same with at least one of
renal perfusion, renal function, fluid status, polyuria, oleguria,
hypoperfusion, hemorrhage shock and GFR.
[0007] In preferred embodiments of the present invention, said
method utilizes a low flow metering device.
[0008] In especially preferred embodiments of the present invention
said low flow metering device incorporates a drop generator and a
droplet counter.
[0009] In a most preferred embodiment of the present invention, the
present invention utilizes a modified version of the low flow
metering device described and claimed in U.S. Pat. No. 6,640,649,
the relevant teachings of which are incorporated herein by
reference.
[0010] Preferably said method further comprises continuously
monitoring and graphically representing, in real minute unit time,
fluctuations in renal flow and renal output.
[0011] The method of the present invention is especially useful for
early prognosis of a disease affiliated with abnormal body fluid
status and kidney stress in medical procedures such as surgery as
well as being useful for providing an indicator of active nephron
mass and kidney function.
[0012] As will be realized the method of the present invention is
useful for detecting a disease affiliated with hypoperfusion.
[0013] The present invention is also useful for detecting a disease
affiliated with hyperperfusion.
[0014] In especially preferred embodiments of the present invention
said method further comprises providing alarm means.
[0015] Another aspect of the present invention relates to the use
of a low flow metering device for the manufacture of a diagnostic
apparatus for continuous monitoring and measuring of urine output
and urine flow of a catheterized patient further comprising linking
the output of said device with means which correlate the same with
at least one of renal perfusion, renal function, fluid status,
polyuria, oleguria, hypoperfusion, hemorrhage shock and GFR.
[0016] In especially preferred embodiments of the present
invention, there is provided a diagnostic method comprising
monitoring and transmitting urine flow rates per minute units of a
catheterized patient to means which correlate the same with at
least one of renal perfusion, renal function, fluid status,
polyuria, oleguria, hypoperfusion, hemorrhage shock and GFR.
[0017] The term "urine flow rates per minute units" as used herein,
is intended to denote that in the apparatus and system of the
present invention the volume of urine flow per a predetermined
average of time intervals of minute units, such as every three
minutes, is plotted on a graph.
[0018] In contradistinction to prior art systems, the present
invention provides real time information in terms of minute units
and thus provides real time information in less than 30 minutes,
preferably less than 20 minutes, and most preferred, in some of its
aspects and utilizations, provides useful and critical information
in less than 10 minutes.
[0019] In a most preferred embodiment of the present invention
there is provided a diagnostic method for determining the
hemodynamic state of a patient comprising administering a diuretic
to a catheterized patient and monitoring and displaying the slope
of urine output per minute units after administration thereof.
[0020] In another preferred embodiment of the present invention
there is provided a diagnostic method for determining the
hemodynamic state of a patient comprising administering a bolus of
fluid to the patient and monitoring and displaying urine flow
reaction to said bolus to determine the state of hydration and
hemorrhagic shock.
[0021] The diagnostic method of the present invention allows for
both the continuous monitoring and transmission of urine output and
flow rate information regarding a catheterized patient to means
which correlate and display the same in real time, and will be
integrated into an apparatus and system supplied to hospitals and
other patient care facilities capable of showing an online and
visual trend of urine output as well as a new clinical parameter,
namely "urine flow". This parameter is generated by online and
continuous monitoring of urine production by the kidneys.
[0022] Another aspect of the present invention, is directed to the
use of a low flow metering device for the manufacture of a
diagnostic system for continuous monitoring and measuring of urine
output and urine flow of a catheterized patient further comprising
linking the output of said device with means which correlate the
same with at least one of renal perfusion, renal function, fluid
status, polyuria, oleguria, hypoperfusion, hemorrhage shock and
GFR.
[0023] In another aspect of the present invention, there is
provided a system for management of the hemodynamic state and
kidney function of the body comprising a low flow metering device
which continuously monitors and measures urine output and urine
flow of a catheterized patient wherein the output of said device is
linked to monitoring means and displaying means which display the
slope of urine output and urine flow rates per minute units.
[0024] The present invention also provides an apparatus for
management of the hemodynamic state and kidney function of the body
comprising a low flow metering device which continuous monitors and
measures urine output and urine flow of a catheterized patient
wherein the output of said device is linked to means for monitoring
and displaying the slope of urine output and urine flow rates per
minute units.
[0025] As is known, often the treating physicians are faced with a
patient or body in a state of unconsciousness, semi-consciousness,
or lack of control, as a result of a disease or trauma or induced
by the medical staff, said patient being in the operating room, the
ICU, the CCU, or in another critical care situation. When the body
is in a steady state, and the kidneys are properly functioning with
no blockages, and when the fluid flow into the body is constant,
such as as a result of IV or IV pumps, then the amount of urine
produced is constant and there is a continuous urine flow which is
also constant.
[0026] Once it has been ascertained that the kidney is capable of
producing urine at a specific flow rate, then the urine flow rate
can be maintained by maintaining the fluid flow rate into the body
as a constant.
[0027] A rule of thumb usually accepted by most doctors establishes
a urine production rate of 1 ml/kg/hr.
[0028] A specific urine flow rate can then be calculated for a
patient and fluid input can be adjusted and urine flow rate
measured in order to establish this specific urine flow rate. As
long as this fluid input rate is maintained and the kidneys
continue to properly function, the urine flow rate will remain
constant and the hydration of a patient can be managed
accordingly.
[0029] By providing the apparatus of the present invention wherein
the urine flow rate is graphically represented in real minute unit
times, it is possible to immediately detect and deal with kidney
stress and kidney malfunction, which have now been found to be
accurate and early indicators of body dysfunction.
[0030] In preferred embodiments of the present invention said
apparatus further comprises means which correlate the same with at
least one of renal perfusion, renal function, fluid status,
polyuria, oleguria, hypoperfusion, hemorrhage shock and GFR.
[0031] Preferably, said apparatus further comprises means for
continuously monitoring and graphically representing in real minute
unit time fluctuations in renal flow and renal output.
[0032] In some preferred embodiments of the present invention said
apparatus comprises means for monitoring and measuring of urine
output and urine flow of a catheterized patient after the
administration of a diuretic.
[0033] In other preferred embodiments of the present invention said
apparatus comprises means which monitors and measures urine output
and urine flow of a catheterized patient after the administration
of a bolus of fluid to a patient in a stable steady state with a
constant fluid input and output.
[0034] In especially preferred embodiments of the present invention
there is provided an apparatus for management of the hemodynamic
state and kidney function of the body comprising a low flow
metering device for continuous monitoring and measuring of urine
output and urine flow of a catheterized patient wherein the output
of said device is linked to means for monitoring and displaying the
slope of urine output and urine flow rates per minute units during
surgery.
[0035] In other preferred embodiments of the present invention
there is provided an apparatus for management of the hemodynamic
state and kidney function of the body comprising a low flow
metering device which continuously monitors and measures urine
output and urine flow of a catheterized patient, wherein the output
of said device is linked to means which monitor and display the
slope of urine output and urine flow rates per minute units after
administration of a nephrotoxic drug.
[0036] In yet another preferred embodiments of the present
invention there is provided an apparatus for management of the
hemodynamic state and kidney function of the body comprising a low
flow metering device for which continuously monitors and measures
urine output and urine flow of a catheterized patient wherein the
output of said device is linked to means which monitor and display
the slope of urine output and urine flow rates per minute units
during administration of a nephrotoxic drug
[0037] As is known, in most catheterized patients measurement of
urine output is performed by an hourly assessment of the urine
volume in a canister or by electronically measuring the volume in a
canister. In contradistinction, by providing reliable, high
resolution and continuous trends of the patient's "urine flow", the
present invention enables continuous online provision of an
indication of renal perfusion, renal function, fluid status,
polyuria, oliguria and GFR.
[0038] The goal of the present invention is to continuously monitor
and display in real time the urine flow in order to optimize fluid
management thereby enabling early prognosis of disease affiliated
with Hypoperfusion such as ARF caused by renal Hypoperfusion,
Intrinsic ARF and Postrenal azotemia etc. and Hyperperfusion such
Edema, the use of diuretics etc.
[0039] It is to be noted that with the tools available in a
standard emergency room and ICU, there is no way to immediately
check for hemorrhage shock or hypoperfusion of an admitted
patient.
[0040] As is known, blood pressure does not reflect blood loss,
since in the case of blood loss vasoconstriction cuts off the
arterioles in less vital organs as perceived by the brain, i.e.,
the legs, the arms, the stomach and even the kidney, in order to
maintain blood flow and blood pressure to the brain. It is for this
reason that up to 35% of patients in an ICU unit suffer from acute
kidney injury since the monitoring teams have no way of knowing
that blood has been cut off from the kidney when the patient is in
a hypoperfusion state, or is suffering from kidney damage as a
result of drugs which act as nephrotoxins.
[0041] Thus, many drugs, and especially anti-cancer drugs, function
as nephrotoxins.
[0042] It has now been found, according to the present invention,
that by measuring urine flow, one can tell when the kidney is in
stress and based thereon, treatment with said drug can be slowed
whereby the drug is administered in a regulated way in order to
limit kidney damage such as by administering the drug over a 4 hour
period instead of in a single immediate dose.
[0043] Today, creatinine is used as a measure of kidney state,
however, creatinine in the blood occurs when the kidney cannot
remove some or all of the creatinine from the body, and this occurs
only when there is already between about 50%-70% kidney damage.
Thus the creatinine test is ineffective for showing kidney damage
of up to and even greater than 50%.
[0044] As is known, the rise of creatinine in the blood as a result
of kidney damage takes hours and even days to occur and therefore
the creatinine test gives its results much too late to reverse
kidney damage.
[0045] It has now been found that with early detection of kidney
damage, i.e., within the first half hour or so, the damage can be
reversed by corrective action, or at a later stage, e.g., within
1-1.5 hours, can be reversed with certain drugs and therefore there
is a need for a marker providing early detection of renal failure,
also known as AKI (acute kidney injury).
[0046] According to the present invention, it has now been
discovered that administration of a loop diuretic such as Fusid
(furosamide) to a patient, results in a rise in the flow rate of
urine per minute units which can be plotted on a graph and the
slope of which is a linear slope. Thus it has now been discovered
that this slope is proportional to the peak flow rate of urine
which is proportional to the total volume of urine produced as a
result of the administration of a diuretic which in turn is
proportional to the state of the kidney in terms of active nephron
mass and which slopes therefore represent the percent of damage to
the kidney. Therefore displaying and noting the linear slope in a
graph generated in a relatively short period of time e.g., in the
first 5 minutes after administration or a similarly chosen minute
time unit, is sufficient to establish a clear picture of kidney
function.
[0047] Similarly it is possible to effect a fluid challenge to the
body, e.g., by administering a predetermined amount of fluid to the
system, such as 200-300 ml, and then monitoring and displaying the
slope of urine output per minute unit after administration thereof,
wherein either the slope, the peak or the total time for the flow
of urine to return to steady state flow, serves to determine the
state of the kidney and the existence or absence of hemorrhagic
shock in a patient.
[0048] Thus in a preferred embodiment of the present invention,
there is provided a diagnostic method for determining the
hemodynamic state of a patient comprising administering a bolus of
fluid to the patient and monitoring and displaying urine flow
reaction to said bolus to determine the state of hydration and
hemorrhagic shock.
[0049] Thus the present invention provides a novel and greatly
needed tool for early detection of kidney damage and the degree
thereof, thereby enabling the timely treatment for reversing the
same
[0050] As a side benefit of the present invention, it has been
discovered that it is not necessary to administer large doses such
as 500 mg of a diuretic such as Fusid, since diuretic drugs are
known to be nephrotoxins and it is sufficient to administer a
smaller dose of 40-50 mg in order to obtain the same effect.
[0051] According to the present invention, it is now possible to
monitor and display kidney function during surgery and to detect
kidney stress in real time, in minute units during surgery, whereby
the surgeon then has a much earlier indicator, than presently
available, that corrective action is immediately required.
[0052] The following is a partial list of diseases that are
associated with and indicated by abnormal urine flow: kidney
perfusion, renal failure, organ perfusion,
pre-operative/post-operative complications, surgical success,
undetected internal trauma, dehydration, response to medication
(antibiotics, diuretics etc), jaundice, shock, preeclampsia,
bladder infection, cystitis, prostatitis, urinary tract infection,
kidney stones, low blood pressure, anuria (lack of urine),
hypovolemia, hypervolemia, pulmonary edema, and hyponatremia,
[0053] The following are explanations of terms and diseases
referred to herein.
ARF (Acute Renal Failure)
[0054] Acute Renal Failure (ARF) is a syndrome characterized by
rapid decline in glomerular filtration rate (hours to days),
retention of nitrogenous waste products, and perturbation of
extracellular fluid volume and electrolyte and acid-base
homeostasis. ARF complicates approximately 5% of hospital
admissions and up to 30% of admissions to intensive care units.
Oliguria (urine output <400 mUd) is a frequent but not
invariable clinical feature (50%). ARF is usually asymptomatic and
diagnosed when biochemical monitoring of hospitalized patients
elevates. a recent increase in blood urea and creatinine
concentrations. It may complicate a wide range of diseases, which
for purposes of diagnosis and management are conveniently divided
into three categories: [0055] (1) Diseases that cause renal
hypoperfusion without compromising the integrity of renal
parenchyma (prerenal ARF, prerenal azotemia) (55%), [0056] (2)
Diseases that directly involve renal parenchyma (intrinsic renal
ARF, renal azotemia) (40%); [0057] (3) Diseases associated with
urinary tract obstruction (postrenal ARF, postrenal azotemia)
(5%).
[0058] Most ARF is reversible, the kidney being relatively unique
among major organs in its ability to recover from almost complete
loss of function. Nevertheless, ARF is associated with major
in-hospital morbidity and mortality, in large part due to the
serious nature of the illnesses that precipitate the ARF. Severe
cases may show clinical or pathologic evidence of ATN. Contrast
nephropathy classically presents as an acute (onset within 24 to 48
h) but reversible.
GFR
[0059] The GFR was originally determined by injecting inulin into
the plasma. Since inulin is not reabsorbed by the kidney after
glomerular filtration, its rate of excretion is directly
proportional to the rate of filtration of water and solutes across
the glomerular filter. In clinical practice however, creatinine
clearance is used to measure GFR. Creatinine is an endogenous
molecule, synthesized in the body, which is freely filtered by the
glomerulus (but also secreted by the renal tubules in very small
amounts). Creatinine clearance is therefore a close approximation
of the GFR. The GFR is typically recorded in milliliters per minute
(ml/min).
EXAMPLE
[0060] A person has a plasma creatinine concentration of 0.01 mg/ml
and in 1 hour he excretes 75 mg of creatinine in the urine. The GFR
is calculated as M/P (where M is the mass of creatinine excreted
per unit time and P is the plasma concentration of creatinine).
GFR = 75 mg 60 mins 0.01 mg / ml = 125 ml / min ##EQU00001## [0061]
Chronic Renal Failure (CRF) develops slowly and gives few symptoms
initially. It can be the complication of a large number of kidney
diseases, such as IgA nephritis, glomerulonephritis, chronic
pyelonephritis and urinary retention. End-stage renal failure
(ESRF) is the ultimate consequence, in which case dialysis is
generally required until a donor for a renal transplant is found.
[0062] Acute Renal failure (ARF) is, as the name implies, a rapidly
progressive loss of renal function, generally characterised by
oliguria (decreased urine production, quantified as less than 400
mL per day in adults,.sup.[1] less than 0.5 mL/kg/h in children or
less than 1 mL/kg/h in infants), body water and body fluids
disturbances and electrolyte derangement. An underlying cause must
be identified to arrest the progress, and dialysis may be necessary
to bridge the time gap required for treating these underlying
causes
[0063] Acute renal failure can be present on top of chronic renal
failure. This is called acute-on-chronic renal failure (AoCRF). The
acute part of AoCRF may be reversible and the aim of treatment,
like in ARF, is to return the patient to their baseline renal
function, which is typically measured by serum creatinine. AoCRF,
like ARF, can be difficult to distinguish from chronic renal
failure, if the patient has not been followed by a physician and no
baseline (i.e., past) blood work is available for comparison.
[0064] Before the advancement of modern medicine renal failure
might be referred to as uremic poisoning. Uremia was the term used
to describe the contamination of the blood with urine. Starting
around 1847 this term was used to describe reduced urine output,
now known as oliguria that was thought to be caused by the urine
mixing with the blood instead of being voided through the
urethra.
[0065] Prerenal azotemia is relatively common, especially in
hospitalized patients. The kidneys normally filter the blood. When
the volume or pressure of blood flow through the kidney drops,
blood filtration also drops drastically, and may not occur at all.
Waste products remain in the bloodstream and little or no urine is
formed, even though the internal structures of the kidney are
intact and functional.
[0066] Lab tests show that nitrogen-type wastes, such as creatinine
and urea, are accumulating in the body (azotemia). These waste
products act as poisons when they accumulate, damaging tissues and
reducing the ability of organs to function. The build-up of
nitrogen waste products and accumulation of excess fluid in the
body are responsible for most of the symptoms of prerenal azotemia
and acute renal failure.
[0067] Prerenal azotemia is the most common form of kidney failure
seen in hospitalized patients. Any condition that reduces blood
flow to the kidney may cause it, including loss of blood volume,
which may occur with dehydration, prolonged vomiting or diarrhea,
bleeding, burns, and other conditions that allow fluid to escape
from circulation.
[0068] Conditions in which the volume is not lost, but in which the
heart cannot pump enough blood, or the blood is pumped at low
volume, also increase risk for prerenal azotemia. These conditions
include shock (such as septic shock), heart failure, and conditions
where the blood flow to the kidney is interrupted, such as trauma
to the kidney, surgery of various types, renal artery embolism, and
other types of renal artery occlusion.
[0069] Thus it will be realized that the method of the present
invention provides the ICU and other medical facilities and
departments with a valuable new diagnostic tool heretofore not
available.
[0070] While the invention will now be described in connection with
certain preferred embodiments in the following examples and with
reference to the attached figures so that aspects thereof may be
more fully understood and appreciated, it is not intended to limit
the invention to these particular embodiments. On the contrary, it
is intended to cover all alternatives, modifications and
equivalents as may be included within the scope of the invention as
defined by the appended claims. Thus, the following examples which
include preferred embodiments will serve to illustrate the practice
of this invention, it being understood that the particulars shown
are by way of example and for purposes of illustrative discussion
of preferred embodiments of the present invention only and are
presented in the cause of providing what is believed to be the most
useful and readily understood description of formulation procedures
as well as of the principles and conceptual aspects of the
invention.
In the figures,
[0071] FIG. 1 is a graphical representation of urine volume
measured by prior art methods during open heart surgery of a
patient;
[0072] FIG. 2 is a graphical representation of urine flow measured
according to the method of the present invention during open heart
surgery of a patient;
[0073] FIG. 3 is a graphical representation of standard blood
pressure measurements over time as well as that of urine flow rate
according to the present invention taken during open heart
surgery.
[0074] FIG. 4 is a graphical representation of mean flow rate of
urine of a patient during bypass open heart surgery;
[0075] FIG. 5 is a graphical representation of standard blood
pressure measurement over time of said patient during said bypass
surgery;
[0076] FIG. 6 is a graphical representation of online per minute
urine flow rate output as an indication for hemorrhagic shock, as
opposed to blood pressure which remains within the range of normal
pressure;
[0077] FIG. 7 is a graphical representation of flow rate versus
time, as well as blood pressure versus time when a bolus of liquid
was administered during induction of hemorrhagic shock;
[0078] FIG. 8 is a graphical representation of urine flow versus
time during bypass surgery;
[0079] FIG. 9 is a graphical representation of urine flow versus
time during bypass surgery in a patient with kidney under
stress;
[0080] FIG. 10 is a graphical representation of online per minute
urine flow rate output after administration of a diuretic
medication to different patients with different kidney status;
[0081] FIG. 11 is a graphical representation of urine flow versus
time after administration of a diuretic from which it can be noted
that the flow slope and the flow peak are proportional.
[0082] FIG. 12 is a graphical representation of urine flow output
as related to dose of diuretic drug administered; and
[0083] FIG. 13 is a graphical representation of urine flow as a
function of time when a body is in a stable state and when a bolus
of fluid is administered.
[0084] Referring now to FIG. 1, there is seen a graphical
representation of urine volume over time of a patient during open
heart surgery wherein according to the graph, there is a constant
increase in volume and therefore no problems are detected.
[0085] Referring now to FIGS. 2 and 3, FIG. 2 is a graphical
representation of urine flow rate measured according to the method
of the present invention and FIG. 3 is a graphical representation
of said flow rate on a graph also showing standard blood pressure
measurements of the same patient during the same period of time. As
will be noted, the method according to the present invention
detected and displayed a severe drop in flow rate, more than an
hour before a drop was noted by the standard blood pressure
measurements.
[0086] Thus from FIGS. 1, 2 and 3, it will be noted that the
standard methods and tools available indicated that the urine
volume continued to increase throughout the procedure and the
reduction in flow was detected by the present method more than an
hour before the reduction of blood pressure was noted, wherein
measurement of blood pressure is used today as the standard for
determining fluid status of a patient.
[0087] Referring now to FIGS. 4 and 5, FIG. 4 records the flow rate
of urine as a function of time of a patient undergoing bypass open
heart surgery, while FIG. 5 records the standard blood pressure
measurements taken of the same patient during the same period of
time. As will be noted, FIG. 5 does not show any problem in the
blood pressure of the patient, while FIG. 4 which recorded flow
rate of urine according to the present invention indicated
significant fluctuations in flow, indicating that the patient was
not receiving sufficient blood to the kidneys which could have been
corrected based on the information provided by the flow rate graph
of the present method by increasing cardiac output during
bypass.
[0088] Referring to FIG. 6, there is graphically represented the
monitoring of a trial of hemorrhagic shock to pigs wherein adult
pigs weighing between 50-70 kg were anesthetized and monitored with
the first hour serving as a reference, the urinary bladder was
pierced and directly catheterized using a foley catheter and then
the pigs were bled with a break between bleeding, each bleeding
being of 10% of the blood volume of the pig for four repeated
bleedings and the final bleeding being of 5%. A diuretic was
administered prior to the test and the flow rate against time in
minutes was monitored.
[0089] As will be noted, the urine flow drops drastically after the
first few minutes of bleeding and after 180 minutes, the urine flow
goes to 0. At this point, vasoconstriction occurs, cutting off
blood to the kidney. The nephrons will be damaged shortly
thereafter. As noted however, the blood pressure remains within the
normal range after 45% of the blood has been removed from the
pigs.
[0090] Referring to FIG. 7, the procedure used in FIG. 6 was
repeated, however a bolus of 500 ml of water was administered
shortly after bleeding was induced. As can be seen the kidney
reacted within minutes resulting in increased urine flow during the
period of the first bleeding. A second bolus of 500 ml was
administered at the outset of bleeding of the second 10%. Once
again, the kidney reacted accordingly resulting in increased urine
flow. A third bolus of 500 ml was administered at the outset of
bleeding of the third 10% however the kidney did not react thereto,
indicating that the kidney was no longer functioning at this
point.
[0091] Referring to FIG. 8, there is seen a graphical
representation of urine flow rate as a function of time as well as
mean blood pressure during bypass surgery wherein bypass began at
minute 100 and ended at around minute 200.
[0092] Before commencement of the bypass surgery either a large
volume of fluid is administered to the patient or a diuretic is
administered or both, in order to maintain kidney activity. As will
be noted, urine flow increased in a typical bell shape as seen in
the figure. At around minute 200, the operation was completed and
the bypass was disconnected. In this case the kidneys were not
affected.
[0093] Referring now to FIG. 9, there is seen a further graph of
urine flow and mean blood pressure for a different patient
undergoing bypass surgery. As will be noted, the urine flow was not
smooth and instead was very erratic. This flow pattern which was
immediately observable indicated that the kidney was under stress
and was damaged and that the patient had acute kidney injury
(AKI).
[0094] As will be realized, by observing urine flow during surgery,
the flow pattern will show the kidney state and indicate when the
kidney gets into stress enabling the surgeon to effect early
intervention and immediately attempt corrective action.
[0095] Referring to FIG. 10, there are seen the patterns of urine
flow as a function of time of different patients to whom a diuretic
medication was administered. It will be noted that the degree of
kidney injury will give different flow peaks. Thus a normal kidney
will give a very high peak while a damaged kidney will give a very
low peak.
[0096] Referring to FIG. 11, there is seen a graphical
representation of urine flow per minute after administration of a
diuretic from which it can be seen that the slope is substantially
linear and proportional to the peak and therefore its path can be
extrapolated within several minutes after administration of the
diuretic thereby providing a very valuable early assessment tool
for kidney function.
[0097] Referring to FIG. 12, there is seen a graph of a urine flow
slope as a function of a diuretic dose of fusid. It will be noted
that after 40 mg of diuretic the drug has no further effect thus
indicating that it is not necessary to administer high drug doses
and that a drug dose of less than 50 mg is sufficient.
[0098] Since diuretic drugs such as fusid are nephrotoxic, this
finding enables the determination of optimum effective doses of
similar drugs, and obviates the administration of excess drugs
which are harmful to the body.
[0099] Thus, by observing urine flow parameters, optimal amount of
drugs can be determined and administered.
[0100] Referring to FIG. 13, there is seen a graphical
representation of urine flow versus time.
[0101] It will be noted that when a patient or body is in a stable
state and the fluids administered to the body are constant, a
healthy kidney is in a condition that it can produce urine flow at
a constant rate. When a small bolus of fluid is administered to the
body, the kidney reacts within minutes to remove the fluid and
return the body to the original steady state.
[0102] Thus, the apparatus of the present invention provides an
invaluable tool for early detection of abnormal conditions not
provided by the standard measuring tools available today, and has
multiple uses in body hydration and kidney management.
[0103] It will be evident to those skilled in the art that the
invention is not limited to the details of the foregoing
illustrative examples and that the present invention may be
embodied in other specific forms without departing from the
essential attributes thereof, and it is therefore desired that the
present embodiments and examples be considered in all respects as
illustrative and not restrictive, reference being made to the
appended claims, rather than to the foregoing description, and all
changes which come within the meaning and range of equivalency of
the claims are therefore intended to be embraced therein.
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