U.S. patent application number 14/645730 was filed with the patent office on 2018-03-15 for fluid therapy method.
This patent application is currently assigned to PLC Medical Systems, Inc.. The applicant listed for this patent is PLC Medical Systems, Inc.. Invention is credited to MARK GELFAND, Andrew V. Halpert, HOWARD LEVIN, Mark Tauscher.
Application Number | 20180071455 14/645730 |
Document ID | / |
Family ID | 54067816 |
Filed Date | 2018-03-15 |
United States Patent
Application |
20180071455 |
Kind Code |
A9 |
Halpert; Andrew V. ; et
al. |
March 15, 2018 |
FLUID THERAPY METHOD
Abstract
A fluid therapy method for an ADHF patient includes setting a
urine output rate desired threshold, setting one or more desired
negative net gain rates, and optionally setting a total fluid loss
goal. The urine output of the patient is monitored and fluid is
automatically administered to the patient at increasing rates to
equal to or approximately match the patient's increasing urine
output rates until the patient's urine output rate reaches the set
urine output rate desired threshold. Thereafter, fluid is
administered to the patient at rates to achieve the set desired
negative net gain rate until the fluid loss goal is reached.
Thereafter, until the end of therapy, fluid is administered to the
patient at rates equal to or approximately equal to the monitored
urine output rates.
Inventors: |
Halpert; Andrew V.;
(Brookline, MA) ; Tauscher; Mark; (Medfield,
MA) ; GELFAND; MARK; (NEW YORK, NY) ; LEVIN;
HOWARD; (TEANECK, NJ) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
PLC Medical Systems, Inc. |
Milford |
MA |
US |
|
|
Assignee: |
PLC Medical Systems, Inc.
|
Prior
Publication: |
|
Document Identifier |
Publication Date |
|
US 20150258277 A1 |
September 17, 2015 |
|
|
Family ID: |
54067816 |
Appl. No.: |
14/645730 |
Filed: |
March 12, 2015 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
12800673 |
May 20, 2010 |
9526833 |
|
|
14645730 |
|
|
|
|
61954089 |
Mar 17, 2014 |
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61M 5/1723 20130101;
A61M 2230/005 20130101; A61M 2202/0496 20130101 |
International
Class: |
A61M 5/172 20060101
A61M005/172 |
Claims
1. A fluid therapy method comprising: setting a urine output rate
desired threshold; setting one or more desired negative net gain
rates; monitoring the urine output of a patient; automatically
administering a fluid to the patient at increasing rates to equal
to or approximately match the patient's increasing urine output
rates until urine output rate reaches the set urine output rate
desired threshold; automatically thereafter administering the fluid
to the patient at rates to achieve the set desired negative net
gain rate.
2. The method of claim 1 further including setting a desired total
fluid loss goal and wherein fluid is automatically administered to
the patient at said rates to achieve the set desired negative net
gain until said set desired fluid loss goal is reached and
thereafter, until the end of therapy, automatically administering
the fluid to the patient at rates equal to or approximately equal
to the monitored urine output rates.
3. The method of claim 1 in which monitoring the urine output rates
includes collecting urine in a urine collection bag and weighing
the urine collection bag as a function of time.
4. The method of claim 1 in which administering fluid to the
patient includes pumping fluid from a fluid bag into the patient
using a fluid pump.
5. The method of claim 4 including monitoring the operation of the
fluid pump over time and/or weighing the fluid bag as a function of
time to determine the rate of fluid infusion.
6. The method of claim 1 in which the fluid is saline or an osmotic
solute.
7. The method of claim 1 further including administering to the
patient a bolus of fluid during therapy.
8. The method of claim 1 further including administering to the
patient a diuretic during the therapy.
9. The method of claim 8 in which the diuretic is administered at
the start of therapy.
10. The method of claim 8 in which the diuretic is administered
automatically.
11. The method of claim 8 in which the diuretic is administered
during the therapy when fluid is administered to the patient at
rates less than the monitored urine output rates according to the
set desired negative net gain rate.
12. The method of claim 1 in which the urine output rate desired
threshold and the desired negative net gain rate are set via stored
default values.
13. The method of claim 1 in which the desired negative net gain
changes during therapy as a function of time.
14. The method of claim 1 in which the user is automatically
informed when the urine rate desired threshold is met.
15. The method of claim 1 in which the user is automatically
informed when the total fluid loss goal is met.
16. The method of claim 1 in which the infusion fluid is hypertonic
saline.
17. The method of claim 1 in which the hypertonic saline infusion
is adjusted based on a urine or serum sodium sensor.
18. A fluid therapy method comprising: setting one or more desired
negative net gain rates; setting a desired fluid loss goal;
monitoring the urine output of a patient; administering a diuretic
to the patient; automatically administering a fluid to the patient
to achieve a set desired negative net gain rate until the desired
fluid loss goal is reached; and thereafter, until the end of
therapy, automatically administering fluid to the patient at rates
equal to or approximately equal to monitored urine output
rates.
19. A method comprising: monitoring the urine output of a patient;
automatically administering a fluid to the patient at rates equal
to or approximately equal to monitored urine output rates until the
urine output rate reaches a desired threshold; and automatically
thereafter administering the fluid to the patient to achieve a set
desired negative net gain rate to take off fluid.
20. The method of claim 19 further including, after a total fluid
loss goal is reached, until the end of therapy, automatically
administering fluid to the patient at rates equal to or
approximately equal to monitored urine output rates.
21. A fluid therapy system comprising: a console including an input
for setting a urine output rate desired threshold and for setting
one or more desired negative net gain rates; a urine output
measuring subsystem; a fluid administration subsystem; and a
controller subsystem responsive to the urine output measuring
subsystem and configured to monitor the urine output rates of a
patient and to control the fluid administration subsystem to:
automatically administer fluid to the patient at rates equal to or
approximately equal to the monitored urine output rate until the
urine output rates reaches the set desired threshold, and
automatically thereafter administer fluid to the patient at rates
to achieve the set desired negative net gain rate.
22. The system of claim 21 in which the console input allows
setting of a total fluid loss goal and the controller subsystem is
configured to administer fluid to the patient at rates equal to or
approximately equal to the monitored urine output rates after a set
total fluid loss goal is reached until the end of therapy.
23. The system of claim 21 in which the urine output measuring
subsystem includes means for weighing a urine collection bag.
24. The system of claim 21 in which the fluid administration
subsystem includes a fluid pump and means for weighing a fluid bag
connected to the fluid pump.
25. The system of claim 21 in which the fluid administration system
is configured to administer both hydrating fluid and a
diuretic.
26. The system of claim 21 in which the controller subsystem is
configured to control the fluid administration system to
automatically administer a diuretic at the start of therapy.
27. The system of claim 21 in which the controller subsystem is
configured to inform the user that the target urine output
threshold has been met.
28. The system of claim 21 in which the controller subsystem is
configured to inform the user that the target urine output
threshold has not been met after an expected time interval.
29. The system of claim 21 in which the controller subsystem is
configured to inform the user that the total fluid loss goal has
been met
30. A method of treating a patient with excess fluid, the method
comprising: setting a urine output rate desired threshold; setting
a negative net fluid gain rate; setting a desired total fluid loss
goal; administering a diuretic to the patient to induce urine
output; for a first therapy period after beginning diuretic
administration, driving the urine output rate of the patient to a
higher level matching or exceeding the set urine output rate
desired threshold by automatically infusing fluid into the patient
at rates which match or closely match the patient's urine output
rates resulting in little or no total fluid loss; and for a second
therapy period after the set urine output rate desired threshold is
reached, inducing fluid loss at said set negative net fluid gain
rate by automatically decreasing the amount of fluid infused and
infusing fluid at rates which are less than but a function of the
patient's urine output rates until said set desired total fluid
loss goal is reached.
31. The method of claim 30 further including a third therapy period
wherein fluid is automatically infused at rates equal to or
approximately equal to the patient's urine output rates after the
desired total fluid loss goal is reached and until the end of
therapy resulting in little or no total fluid loss during the third
therapy period to prevent patient dehydration.
32. The method of claim 30 further including administering a
diuretic to the patient during the second therapy period.
33. The method of claim 32 wherein the diuretic is administered
automatically.
34. The method of claim 30 in which monitoring the urine output
rates includes collecting urine in a urine collection bag and
weighing the urine collection bag as a function of time.
35. The method of claim 30 in which administering fluid to the
patient includes pumping fluid from a fluid bag into the patient
using a fluid pump and automatically controlling the operation of
the fluid pump.
36. The method of claim 35 including monitoring the operation of
the fluid pump over time and/or weighing the fluid bag as a
function of time to determine the rate of fluid infusion.
37. The method of claim 30 in which the infusion fluid is saline or
an osmotic solute.
38. The method of claim 30 further including automatically
administering to the patient a bolus of fluid during therapy.
39. The method of claim 30 further including automatically
administering to the patient the diuretic.
40. The method of claim 30 in which the urine output rate desired
threshold, the desired negative net gain rate, and the desired
total fluid loss goal are set via stored default values.
41. A fluid therapy method comprising: administering a diuretic to
the patient to induce urine output; automatically monitoring the
patient's urine output rates; for a first therapy period after
administration of the diuretic, driving the urine output rate of
the patient to a higher level by automatically controlling an
infusion pump to infuse fluid into the patient at rates which match
or closely match the monitored patient's urine output rates until a
set urine output rate threshold is reached resulting in little or
no total fluid loss during the first therapy period; and for a
second therapy period after the set urine output rate threshold is
reached, inducing fluid loss at a set negative net fluid gain rate
by automatically controlling the infusion pump to decrease the
amount of fluid infused and controlling the infusion pump to infuse
fluid at rates which are less than but a function of the patient's
urine output rates until a set desired total fluid loss goal is
reached during the second therapy period.
42. The method of claim 41 further including a third therapy period
wherein the infusion pump is controlled to infuse fluid at rates
equal to or approximately equal to the patient's urine output rates
after the set desired total fluid loss goal is reached and until
the end of therapy resulting in little or no total fluid loss
during the third therapy period to prevent patient hydration.
43. A fluid therapy system comprising: a console including an input
for setting a urine output rate desired threshold and for setting a
desired negative net fluid gain rate; a urine output measuring
subsystem; a fluid administration subsystem; and a controller
subsystem, responsive to the urine output measuring system and
configured to monitor the urine output rates of a patient and to
control the fluid administration subsystem to automatically: drive
the urine output rate of the patient to a high level matching or
exceeding the set urine output rate desired threshold by
controlling the fluid administration subsystem to infuse fluid into
the patient at rates that match or closely match the patient's
urine output rates as measured by the urine output measuring
subsystem resulting in little or no total fluid loss during a first
therapy period; and after the set urine output rate desired
threshold is reached, inducing fluid loss at said set desired
negative net fluid gain rate by controlling the fluid
administration subsystem to infuse fluid at rates which are less
than but a function of the patient's urine output rates as measured
by the urine output measuring subsystem until said set desired
total fluid loss goal it reached.
44. The system of claim 43 in which the controller subsystem is
further configured to automatically control the fluid
administration subsystem to infuse fluid at rates equal to or
approximately equal to the patient's urine output rates as measured
by the urine output measuring subsystem after the desired total
fluid loss goal is reached and until the end of therapy resulting
in little or no total fluid loss during a third therapy period to
prevent patient dehydration.
45. The system of claim 43 further including a subsystem for
automatically administering a diuretic to the patient before the
first therapy period and, optionally, during the second therapy
period.
Description
RELATED APPLICATIONS
[0001] This application claims benefit of and priority to U.S.
Provisional Application Ser. No. 61/954,089 filed Mar. 17, 2014
under 35 U.S.C. .sctn..sctn.119, 120, 363, 365, and 37 C.F.R.
.sctn.1.55 and .sctn.1.78 and is incorporated herein by this
reference.
FIELD OF THE INVENTION
[0002] This invention relates to a patient hydration system and
method wherein the rate of hydration fluid delivered to the patient
is automatically adjusted based on the urine output and clinician
settings in order to reach a clinician desired net fluid loss by
the patient.
BACKGROUND OF THE INVENTION
[0003] Acute decompensated heart failure (ADHF) is the largest
cause of hospitalization in the United States among patients 65 and
older. See Lloyd-Jones D, Adams R, Carnethon M, et al. Heart
disease and stroke statistics--2009 update: a report from the
American Heart Association Statistics Committee and Stroke
Statistics Subcommittee. Circulation 2009; 119(3):e21-e181
incorporated herein by this reference. These patients often enter
the emergency room with significant volumes of excess fluid and a
number of complications due to this excess fluid. Complications can
include dyspnea, orthopnea, peripheral edema, and pulmonary
edema.
[0004] Current treatment for these patients is to administer a
number of doses of a diuretic to increate urination to enable the
patient to lose the excess fluid. This therapy can take a number of
days while the patient requires vigilant monitoring in an intensive
care unit.
[0005] A recent study that attempted to determine the ideal
diuretic dose for ADHF patients demonstrated how poorly patients
fare with the current therapy. Across all treatment groups, 42% of
patients enrolled in the trial died, were re-hospitalized, or had
an emergency department visit within 60 days of treatment. See
Felker G M, Lee K L, Bull D A, et al. Diuretic Strategies in
Patients with Acute Decompensated Heart Failure (DOSE). The New
England Journal of Medicine, 2011; 364(9):797-805 incorporated
herein by this reference.
[0006] There are a number of factors that contribute to the poor
prognosis of these patients. Patients with ADHF often have a number
of co-morbidities, complicating their treatment and giving them a
poor prognosis. These patients are often already taking a diuretic
chronically, which lessens the impact of the diuretics when they
are administered during their hospitalization. This also
contributes to the fact that patient response to diuretics is
unpredictable. Some patients may begin diuresis immediately after
diuretic injection, others may require additional doses to induce
diuresis.
[0007] A paradox of the ADHF patient involves the fact that while
these patients may have 40 additional liters of fluid in their
body, they may be intravascularly dehydrated. The extra fluid may
be contained within the patient's cells and in the extra-cellular
space ("third space"). The injection of diuretics then only causes
fluid to be lost from the already depleted intravasculature. This
can lead to a condition known as "diuretic resistance", wherein the
patient's kidney attempts to retain the fluid lost after the
initial doses of diuretic and fails to respond to increasing doses
of diuretic. As fluid retention increases, the patient's urine
output can drop to zero. Once the patient fails to respond to
diuretics, treatment becomes very difficult. One of the ways ADHF
kills patients is by retaining so much fluid that the fluid begins
to build up in the patient's lungs, eventually causing pulmonary
edema and eventually causing the lungs to fail. Diuretics are the
most common method used to remove that excess fluid and prevent
pulmonary edema. If diuretics fail to induce urine output due to
diuretic resistance, the clinician loses an effective tool for
protecting the patient from pulmonary edema.
[0008] The intravascular depletion caused by diuretic therapy can
also reduce blood supply to the kidney, causing additional damage
to the kidney.
[0009] Ultrafiltration therapy has been studied as a potential
method for removing fluid from patients at risk of diuretic
resistance. The therapy requires a pump that removes blood from the
patient and passes the blood through a filter. The filter has small
holes that allow fluid and electrolytes to be removed from the
blood, but does not pass red blood cells or proteins. The blood is
then returned to the body with some portion of the fluid and
electrolytes removed. Ultrafiltration can be performed using a
dialysis machine or a dedicated device, such as the Aquadex
(Gambro, Brooklyn Park, Minn.).
[0010] While a number of studies have demonstrated that
Ultrafiltration can effectively remove fluid from ADHF patients,
one of the largest studies of the therapy to date has found that
Ultrafiltration may lead to more kidney damage than diuretic
therapy. See Bart B A, Goldsmith S R, Lee K L, et al.
Ultrafiltration in Decompensated Heart Failure with Cardiorenal
Syndrome, The New England Journal of Medicine, 2012;
367(24):2296-304 incorporated herein by this reference.
[0011] Hypertonic saline I.V. may be an effective in medical
management of cerebral (brain) edema and elevated intracranial
pressure (ICP). It is a critical component of perioperative care in
neurosurgical practice. Traumatic brain injury (TBI), arterial
infarction, venous hypertension/infarction, intracerebral
hemorrhage (ICH), subarachnoid hemorrhage (SAH), tumor progression,
and postoperative edema can all generate clinical situations in
which ICP management is a critical determinant of patient outcomes.
Use of hypertonic saline and other osmotic agents is among the most
fundamental tools to control ICP. Recently several scientific
papers taught the counterintuitive use of hypertonic saline to
treat congestive heart failure (CHF or simply heart failure)
patients with fluid overload resistive to diuretics. CHF patients
retain salt and water to maintain blood pressure and their salt
intake is severely limited by the traditional therapy paradigm.
[0012] Patema S, Di Pasquale P, Parrinello G, et al. in "Changes in
brain natriuretic peptide levels and bioelectrical impedance
measurements after treatment with high-dose furosemide and
hypertonic saline solution versus high-dose of furosemide alone in
refractory congestive heart failure: a double-blind study" (7 Am
Coll Cardiol 2005; 45:1997-2003; further called Patena Paper) and
Stevenson et al. in JACC Vol. 45, No. 12, 2005 Editorial Comment on
the Patena Paper describe and comment on results from the
randomized study of 94 patients hospitalized with clinical volume
overload. The study suggests that the administration of sodium may
paradoxically treat the sodium-retaining state. For acute diuresis,
very high doses of loop diuretic furosemide (500 to 1,000 mg) were
administered twice daily with either hypertonic saline or vehicle
infusion concomitantly. Patients receiving hypertonic saline had
greater volume loss and were discharged sooner, with better renal
function and higher serum sodium.
[0013] According to Stevenson, the mechanisms by which in the acute
phase of CHF the I.V. infusion of excess saline load facilitated
diuresis are open to interpretation and complex. Unmistakably
though, there was a larger amount of free water diuresis in the
hypertonic saline group. This may relate in part to an acute
osmotic effect of hypertonic saline to increase mobilization of
extravascular fluid into the central circulation and renal
circulation. Direct intratubular effects of sodium flooding may
overwhelm the postdiuretic NaCl retention and over time may reduce
the diuretic "braking" phenomenon by which fluid escaping past the
ascending limb is captured downstream. Neurohormone levels may have
been suppressed by hypertonic saline. Both increased intravascular
volume and greater delivery of sodium to the distal tubule should
inhibit the rennin-angiotensin-aldosterone system Inhibition of
aldosterone release could explain the lower relative potassium
excretion in the high sodium group, Reduction in angiotensin II
levels could lead also to a decrease in antidiuretic hormone (ADH)
vasopressin release despite temporary increase in serum osmolarity.
There may also be a small contribution of increased intravascular
volume to stimulation of the low-pressure and high-pressure
baroreceptors that inhibit vasopressin release. Decreased levels of
vasopressin could reduce the aquaporin channels through which water
is reabsorbed, leading to the greater free water excretion
observed. Reduced vasopressin also might also decrease compensatory
over-expression of the sodium transporter in the ascending limb,
which diminishes diuretic effect.
SUMMARY OF THE INVENTION
[0014] It is therefore the object of this invention to provide a
fluid management system and a method for allowing the clinician to
reliably achieve and maintain a high urine rate and then control
the patient's fluid loss. A system in accordance with the invention
makes the nurse's job easier. One method may treat patents with
excess fluid. Another method is a fluid therapy method.
[0015] Featured is a method of treating a patient with excess
fluid. The preferred method comprises setting a urine output rate
desired threshold, setting a negative net fluid gain rate, and
setting a desired total fluid loss goal. A diuretic is preferably
administered to the patient to induce urine output. For a first
therapy period after beginning diuretic administration, the urine
output rate of the patient is driven to a higher level matching or
exceeding the set urine output rate desired threshold. Such high
urine output rates are achieved by automatically infusing fluid
into the patient at rates which match or closely match the
patient's urine output rates resulting in little or no total fluid
loss. For a second therapy period after the set urine output rate
desired threshold is reached, fluid loss is induced at the set
negative net fluid gain rate by automatically decreasing the amount
of fluid infused and infusing fluid at rates which are less than
but a function of the patient's urine output rates until the
desired total fluid loss goal is reached. A third therapy period
may be involved wherein fluid is automatically infused at rates
equal to or approximately equal to the patient's urine output rates
after the desired total fluid loss goal is reached and until the
end of therapy resulting in little or no total fluid loss during
the third therapy period to prevent patient dehydration.
[0016] The method may further include administering a diuretic to
the patient during the second therapy period. The diuretic may be
administered automatically. Monitoring the urine output rates
preferably includes collecting urine in a urine collection bag and
weighing the urine collection bag as a function of time.
Administering fluid to the patient preferably includes pumping
fluid from a fluid bag into the patient using a fluid pump and
automatically controlling the operation of the fluid pump. The
method may include monitoring the operation of the fluid pump over
time and/or weighing the fluid bag as a function of time to
determine the rate of fluid infusion.
[0017] The infusion fluid may be saline or an osmotic solute. The
method may further include automatically administering to the
patient a bolus of fluid during therapy. The urine output rate
desired threshold, the desired negative net gain rate, and the
desired total fluid loss goal can be set via stored default
values.
[0018] One fluid therapy method includes administering a diuretic
to the patient to induce urine output and automatically monitoring
the patient's urine output rates. For a first therapy period after
administration of the diuretic, the urine output rate of the
patient is driven to a higher level by automatically controlling an
infusion pump to infuse fluid into the patient at rates which match
or closely match the monitored patient's urine output rates until a
set urine output rate threshold is reached resulting in little or
no total fluid loss during the first therapy period. For a second
therapy period after the set urine output rate threshold is
reached, fluid loss is induced at a set negative net fluid gain
rate by automatically controlling the infusion pump to decrease the
amount of fluid infused and controlling the infusion pump to infuse
fluid at rates which are less than but a function of the patient's
urine output rates until a set desired total fluid loss goal is
reached during the second therapy period. The method may further
include a third therapy period wherein the infusion pump is
controlled to infuse fluid at rates equal to or approximately equal
to the patient's urine output rates after the set desired total
fluid loss goal is reached and until the end of therapy resulting
in little or no total fluid loss during the third therapy period to
prevent patient hydration.
[0019] Also featured is a fluid therapy system comprising a console
including an input for setting a urine output rate desired
threshold and for setting a desired negative net fluid gain rate.
The system further includes a urine output measuring subsystem and
a fluid administration subsystem. A controller subsystem is
responsive to the urine output measuring system and is configured
to monitor the urine output rates of a patient. The controller
subsystem is configured to control the fluid administration
subsystem to automatically drive the urine output rate of the
patient to a high level matching or exceeding the set urine output
rate desired threshold by controlling the fluid administration
subsystem to infuse fluid into the patient at rates that match or
closely match the patient's urine output rates as measured by the
urine output measuring subsystem resulting in little or no total
fluid loss during a first therapy period. After the set urine
output rate desired threshold is reached, the controller subsystem
is configured to induce fluid loss at said set desired negative net
fluid gain rate by again controlling the fluid administration
subsystem to infuse fluid at rates which are now less than but a
function of the patient's urine output rates as measured by the
urine output measuring subsystem until the set desired total fluid
loss goal it reached. The controller subsystem may be further
configured to automatically control the fluid administration
subsystem to infuse fluid at rates equal to or approximately equal
to the patient's urine output rates as measured by the urine output
measuring subsystem after the desired total fluid loss goal is
reached and until the end of therapy resulting in little or no
total fluid loss during a third therapy period to prevent patient
dehydration. The system may further include a subsystem for
automatically administering a diuretic to the patient before the
first therapy period and, optionally, during the second therapy
period.
[0020] The subject invention, however, in other embodiments, need
not achieve all these objectives and the claims hereof should not
be limited to structures or methods capable of achieving these
objectives.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0021] Other objects, features, and advantages will occur to those
skilled in the art from the following description of a preferred
embodiment and the accompanying drawings, in which:
[0022] FIG. 1 is a view of an example of a system in accordance
with the invention;
[0023] FIG. 2 is a flow chart depicting an example of the method of
the invention and/or the primary steps associated with the
programming of the controller in the system of FIG. 1; and
[0024] FIGS. 3-5 are examples of hydration profiles in accordance
with methods of the invention and/or stored default values for the
system of FIG. 1.
DETAILED DESCRIPTION OF THE INVENTION
[0025] Aside from the preferred embodiment or embodiments disclosed
below, this invention is capable of other embodiments and of being
practiced or being carried out in various ways. Thus, it is to be
understood that the invention is not limited in its application to
the details of construction and the arrangements of components set
forth in the following description or illustrated in the drawings.
If only one embodiment is described herein, the claims hereof are
not to be limited to that embodiment. Moreover, the claims hereof
are not to be read restrictively unless there is clear and
convincing evidence manifesting a certain exclusion, restriction,
or disclaimer.
[0026] In one example, the fluid management system comprises a
urine collection system capable of measuring the patient's urine
output, a controller that reads the output of the urine collection
system and is capable of taking input from a user, and an infusion
pump system that receives commands from the controller based on the
urine collection readings and the user input. The urine collection
system is connected to the patient via a catheter interface, such
as a Foley catheter or a nephrostomy tube. The infusion pump system
is connected to the patient via an infusion catheter.
[0027] Prior to beginning therapy, the clinician uses the fluid
management system to set the urine rate they would like the patient
to achieve before net fluid loss begins. The urine rate target can
be as low as zero and as high a liter an hour or more. The
clinician also sets the fluid loss profile the device should use
once the patient achieves the target urine rate.
[0028] Additionally, the clinician can be given the option of
setting a total loss fluid target. This is the total fluid loss the
clinician would like the patient to achieve. The clinician is also
given the option of setting an additional fluid infusion volume as
a fluid challenge to help induce urine output.
[0029] The patient then receives an injection of a diuretic, such
as Furosemide (Lasix), either in a bolus or via a continuous IV
drip. The combination of Furosemide and matched replacement has
been demonstrated in a number of trials to induce high urine rates.
See Marenzi, Giancarlo, Prevention of Contrast Nephropathy by
Furosemide with Matched Hydration: The MYTHOS Trial, JACC:
Cardiovascular Interventions, Volume 5, Issue 1, January 2012,
Pages 90-97; Dorval, Jean-Francois, Feasibility study of the
RenalGuard.TM. balanced hydration system: A novel strategy for the
prevention of contrast-induced nephropathy in high risk patients,
International Journal of Cardiology. Int J Cardiol (2011),
10.1016/j.ijcard.2011.11.035 Dec. 29, 2011; and Briguori, Carlo,
Renal Insufficiency After Contrast Media Administration Trial II
(REMEDIAL H) Circulation, August 2011; Online ISSN: 1524-4539 all
incorporated herein by this reference.
[0030] If target urine rate is not met within a user adjustable
period of time, such as 30 minutes, the user is informed by an
alert that the target urine rate has not been met. The alert recurs
every interval until the target urine rate is met. Until the target
urine rate is met, the fluid management system continues matched
replacement.
When the target urine rate is met, an alert may be provided to the
clinician to inform them that the target urine output rate has been
reached and that the negative match profile we be initiated.
[0031] If clinically indicated, the clinician has the opportunity
to indicate to the system that the negative match profile should
begin as soon as therapy is initiated. This can be used in a
patient who is already producing sufficient urine and does not
require increased urine output to be induced.
[0032] Once the target urine rate is reached, then the set negative
match profile automatically begins. A negative match profile can be
as simple as match a set volume less than the patient's urine
output every hour (i.e. -100 ml/hr). The user can set more
complicated negative match profiles, such as match -50 ml/hr for
the first hour, -75 ml/hr the second hour, -100 ml/hr the third
hour and so on. The user can also select from pre-set profiles,
such as a profile that slowly increases the negative match or one
that aggressively increases the hourly negative match. The interval
can also be more or less than an hour.
[0033] If the measured urine rate drops below the current set
negative match rate or below another urine rate alert setting, the
user is alerted. Alerts of low urine rate can occur directly via
the fluid management system's screen or remotely through the
hospital's network. Negative match profile continues until the
clinician stops therapy. If the clinician set a total fluid loss
target, the fluid management system stops the negative match
profile when the patient reaches the total fluid loss target and
resumes balanced hydration. An alert can be provided to the
clinician to inform them that the fluid loss target has been
met.
[0034] The hydration fluid could be any number of fluids, including
but not limits to isotonic saline ("normal"), hypertonic saline,
Ringer's Lactate, etc.
[0035] The fluid management system and method described enable the
clinician to cause the patient to lose a set volume of fluid each
hour while limiting the patient's hourly fluid loss. This enables
the patient to maintain a brisk diuresis without becoming
intravascularly dehydrated, preventing one of the major causes of
diuretic resistance. See DOSE
http://www.ncbi.nlm.nih.gov/m/pubmed/213664721 and CARRESS
http://view.ncbi.nlm.nih.gov/pubmed/23131078 both incorporated
herein by this reference.
[0036] One preferred example of a patient hydration system
according to this invention includes unit 34, FIG. 1 typically
mounted on IV pole 84. See U.S. Pat. Nos. 7,727,222 and 8,444,623
incorporated herein by this reference. Unit 34 has programmable
controller electronics therein. There is an infusion subsystem
including pump 22 responsive to source of infusion fluid 24 for
infusing a patient with hydration fluid. Bag 100 may optionally
include a diuretic infused into the patient by pump 102 controlled
by the controller of the console 34. There is also a urine output
measurement subsystem for determining the amount of urine output by
the patient. In this particular example, source of infusion fluid
bag 24 is hung on hook 92 and urine collection chamber or bag 52 is
hung on hook 91 via chain 53 and hook 90. Unit 34 includes one or
more weight scales such as an electronic strain gage or other means
to periodically detect the weight of the collected urine in bag 52
and, if desired, the weight of the remaining hydration fluid in bag
24. Hooks 91 and 92 are connected to a system of levers which
translates force to a scale such as a strain gage within unit 34.
The strain gage converts force into an electronic signal that can
be read by a controller. Suitable electronic devices for accurately
measuring the weight of a suspended bag with urine are available
from Strain Measurement Devices, 130 Research Parkway, Meriden,
Conn., 06450. These devices include electronic and mechanical
components necessary to accurately measure and monitor weight of
containers with medical fluids such as one or two-liter plastic
bags of collected urine. For example, the overload proof single
point load cell model S300 and the model S215 load cell from Strain
Measurement Devices are particularly suited for scales, weighing
bottles or bags in medical instrumentation applications. Options
and various specifications and mounting configurations of these
devices are available. These low profile single point sensors are
intended for limited space applications requiring accurate
measurement of full-scale forces of 2, 4, and 12 pounds-force. They
can be used with a rigidly mounted platform or to measure tensile
or compressive forces. A 10,000.OMEGA. wheatstone bridge offers low
power consumption for extended battery life in portable products.
Other examples of gravimetric scales used to balance medical fluids
using a controller controlling the rates of fluid flow from the
pumps in response to the weight information can be found in U.S.
Pat. Nos. 5,910,252; 4,132,644; 4,204,957; 4,923,598; and 4,728,433
incorporated herein by this reference.
[0037] It is understood that there are many ways known in the art
of engineering to measure weight and convert it into computer
inputs. Regardless of the implementation, the purpose of the weight
measurement is to detect the increasing weight of the collected
urine in the bag 52 and to adjust the rate of infusion or hydration
based on the rate of urine flow by the patient by controlling
infusion pump 22.
[0038] Unit 34 is also typically equipped with the user interface.
The interface allows the user to set (dial in) the parameters of
therapy such as the urine output rate desired threshold, a negative
net gain rate, and/or a desired total fluid loss goal. Display
indicators on the console show the set values and/or the current
status of therapy: the elapsed time, the net fluid gain or loss,
the amount of fluid infused, the amount of fluid loss, the loss
rate, and/or the infusion rate, and the like.
[0039] The user interface may also include alarms. The alarms
notify the user of therapy events such as an empty fluid bag or a
full collection bag as detected by the weight scale. In one
proposed embodiment, the urine is collected by gravity. If urine
collection unexpectedly stops for any reason, the system will
reduce and, if necessary, stop the IV infusion of fluid and alarm
the user. Alternatively, the console can include the second (urine)
pump similar to infusion pump 22. This configuration has an
advantage of not depending on the bag height for drainage and the
capability to automatically flush the catheter if it is occluded by
temporarily reversing the pump flow direction.
[0040] Infusion pump 22 pumps infusion fluid from bag 24 into the
patient and is controlled by the controller electronics within the
unit which monitors the weight of the urine in urine collection bag
52.
[0041] The electronic controller may also incorporate a more
advanced feature allowing the physician to set a hydration profile
selected from stored profiles depicted in FIGS. 3-5. See also
co-pending U.S. application Ser. Nos. 11/408,391; 11/408,851; and
11/409,171 filed Apr. 21, 2006 which are incorporated herein by
this reference.
[0042] In accordance with one example, the infusion set includes
infusion bag "spike" connector 20 received in infusion fluid bag
24, luer connector 28 for receiving an IV needle, and tubing
extending therebetween and placed within infusion pump 22. The
urine collection set typically includes urine collection bag 52,
Foley catheter connector 26 for connection to a Foley catheter, and
tubing extending between the urine collection bag, and connector
26. The infusion set and the urine collection set are preferably
placed together as a kit for the hydration unit in sealed bag for
storage in a sterile fashion until ready for use. The integrated
infusion set includes an IV bag spike, a Luer-to-Foley connector
for priming, and a urine collection set includes an integrated
urine bag.
[0043] The power requirements are typically 115/220 VAC, 60/50 Hz,
25 VA. An auxiliary ground post (potential equalization) for the
device is on the rear of the case (not shown). An RS 232 port is
also provided. When mounted on an I.V. Pole, the system requires an
area of approximately 20.times.20 inches. Console 34 is placed on
the pole so that the urine collection bag 52 is above floor level
and not touching the floor or other equipment. Urine collection bag
chain 53 is passed through motion restrictor ring 60 to prevent
excessive swinging of the bag. Urine collection bag 52 is below the
level of patient to facilitate urine drainage, and urine 52 and
hydration fluid 24 bags are hanging freely on hooks 90 and 92,
respectively, and not supported or impeded. Protection tubes 94 and
96 shown in phantom may be provided about hooks 91 and 92.
[0044] The system maintains hydration balance by measuring patient
urine output and infusing hydration fluid (prescribed by physician)
into the patient I.V. based on the patient's urine output and the
clinician's settings. In addition to urine volume replacement, the
system implements a user-set net fluid loss. The system also allows
rapid infusion of a Bolus of fluid at the user request. The amount
of Bolus can be selected by user and typically the bolus is infused
over 30 minutes. Unit 34 typically includes a microcontroller
device that has means for measuring urine output and the ability to
infuse hydration fluid into the patient. The infusion set allows
the console to pump fluid from a hydration fluid bag to the patient
at a controlled rate. The disposable urine collection set collects
the patient's urine to allow it to be measured accurately. Unit 34
is also equipped with an internal battery that can sustain
operation in the event of power outage or during short periods of
time, for example, when the patient is moved. Unit 34 may include
roller pump 22, a user interface, two weighing scales (not shown),
air detector 70, post-pump pressure sensor 72, an electrical
connector for AC power, and mechanical interfaces for holding the
set in place. Console 34 controls the rate at which fluid is
infused and monitors urine volume by weight measurement.
[0045] In the subject invention, a controller e.g., a
microprocessor or microcontroller or other circuitry (e.g., a
comparator) in console 34, FIG. 1 controls hydration pump 22 to
infuse the patient with hydration fluid based on the patient's
urine output and keeps track of the hydration fluid injected in two
ways to provide safety and redundancy. The preferred hydration
fluid measurement subsystem includes, first, as discussed above,
the weight of hydration fluid source 24, FIG. 1 which is monitored.
Urine output is also monitored. In addition, the operation history
of infusion pump 22 may be monitored by controller 100. The
controller may store values representing both of these measurements
in a memory such as a PROM and the controller is programmed to
store the hydration fluid amounts administered via the hydration
fluid measurement strain gauge, and the controller is also
programmed to store the hydration fluid amount administered by
monitoring of the hydration pump operation history.
[0046] One fluid therapy method includes setting a urine output
rate desired threshold (e.g., 400 ml/hr). Such a desirably high
urine output rate is uniquely achieved by first automatically
balancing as shown in FIG. 3. One or more desired negative net gain
rates are also set (e.g., -100 ml/hr). A desired total fluid loss
goal is also set (e.g., 7004000 ml). The urine output of the
patient is monitored and fluid is automatically administered to the
patient at a rate equal to or approximately equal to the monitored
urine output rate until the urine output rate reaches the set
desired threshold. Thereafter, fluid is automatically administered
to the patient at the set desired negative net gain rate until the
total fluid loss goal is reached. Thereafter, until the end of
therapy, fluid is automatically administered to the patient at a
rate equal to or approximately equal to the monitored urine output
rate to prevent hydration.
[0047] Monitoring the urine output rate may include collecting
urine in a urine collection bag and weighing the urine collection
bag as a function of time. Administering fluid to the patient may
include pumping fluid from a fluid bag into the patient using a
fluid pump. The method may include monitoring the operation of the
fluid pump over time and/or weighing the fluid bag as a function of
time to determine the rate of fluid infusion. A bolus of fluid may
be administered during therapy. A diuretic may be administered
during the therapy, e.g., at the start of therapy. The diuretic may
be administered during the therapy when fluid is administered to
the patient at a rate less than the monitored urine output rate
according to the set desired negative net gain rate. The urine
output rate desired threshold, the desired negative net gain rate,
and/or the desired total fluid loss goal can be set via stored
default values. Exemplary values are 400 ml/hr, -100 ml/hr, and
1000 ml, respectively. In some examples, the desired negative net
gain changes during therapy as a function of time, e.g., -50 ml/hr
for 1 hour, then -100 ml/hr for one hour, and then -150 ml/hr for
another hour.
[0048] One fluid therapy method comprises setting one or more
desired negative net gain rates, setting a desired total fluid loss
goal, monitoring the urine output of a patient, administering
diuretics to the patient, automatically administering the fluid to
the patient at the set desired negative net gain rate until the
total fluid loss goal is reached, and thereafter, until the end of
therapy, automatically administering the fluid to the patient at a
rate equal to or approximately equal to the monitored urine output
rate.
[0049] A fluid therapy system in one example includes a console
including an input section 33 for setting a urine output rate
desired threshold, for a particular patient, for setting one or
more desired negative net gain rates, and for setting a desired
total fluid loss goal. The controller reads all three settings
which may be stored in memory. See console 34, FIG. 1, step 200,
FIG. 2. The system also includes a urine output measuring
subsystem, a fluid administration subsystem, and a controller
responsive to the urine output measuring subsystem and configured
to monitor the urine output of a patient. The controller is
programmed to control the fluid administration subsystem to
automatically administer fluid to the patient at a rate equal to or
approximately to the monitored urine output rate until the urine
output rate reaches the set desired threshold, step 202. The
controller monitors the urine output rate and is programmed to
respond when the set urine output rate is reached. The controller
is programmed, in response to the set urine output rate is reached
to automatically thereafter administer fluid to the patient at the
set desired negative net gain rate until the set total fluid loss
goal is reached, steps 204, 206. The controller monitors the total
fluid loss and when the goal is reached the controller is
programmed to respond. The controller is programmed in response to
the desired total fluid loss goal being reached to thereafter,
until the end of therapy, automatically administer fluid to the
patient at a rate equal to or approximately equal to the monitored
urine output rate, step 208. The urine output measuring subsystem
may include means for weighing a urine collection bag. The fluid
administration subsystem may include a fluid pump and means for
weighing a fluid bag connected to the fluid pump.
[0050] Featured is a method of treating a patient with excess
fluid. A urine output rate desired threshold, and/or a negative net
fluid gain rate, a desired total fluid loss goal are set in unit
34, FIG. 1. A diuretic is administered (manually or automatically)
to the patient to induce urine output at hour 0 of therapy, FIG. 3.
For a first therapy period after administration of the diuretic,
the urine output rate of the patient is driven to a higher level
matching or exceeding the set urine output rate (e.g., over 400
ml/hr) desired threshold by automatically infusing fluid into the
patient at rates which match or closely match the patient's urine
output rates resulting in little or no total fluid loss as shown in
hours 0-2 of therapy in FIG. 3. For a second therapy period after
the set urine output rate desired threshold is reached, fluid loss
is induced at the set negative net fluid gain rate by automatically
decreasing the amount of fluid infused and infusing fluid at rates
which are less than but a function of the patient's urine output
rates until the set desired total fluid loss goal is reached as
shown in hours 2-13 of therapy in FIG. 3. Optionally, a diuretic
may again be administered (manually or automatically) during this
second therapy period as shown at hour 10. In the third therapy
period, fluid is automatically infused at rates equal to or
approximately equal to the patient's urine output rates after the
desired total fluid loss goal is reached and until the end of
therapy resulting in little or no total fluid loss during the third
therapy period to prevent patient dehydration as shown in hours
13-15 of the therapy in FIG. 3.
[0051] Monitoring the urine output rates may include collecting
urine in a urine collection bag 52, FIG. 1 and weighing the urine
collection bag as a function of time. Administering fluid to the
patient may include pumping fluid from a fluid bag 24 into the
patient using a fluid pump 22 and automatically controlling the
operation of the fluid pump. The controller may include software
instructions for monitoring the operation of the fluid pump over
time and/or weighing the fluid bag as a function of time to
determine the rate of fluid infusion. See for example, U.S. Pat.
Nos. 7,727,222 and 8,444,623 incorporated herein by this reference.
The infusion fluid may be saline or an osmotic solute. The urine
output rate desired threshold, the desired negative net gain rate,
and the desired total fluid loss goal may also be set via stored
default values.
[0052] The clinical efficacy of this therapy has been established
based on three sets of data.
[0053] The ability of the system to induce high urine rates by
measuring a patient's urine output and infusing a volume of
hydration fluid has been well established. This has been
demonstrated in hundreds of patients in studies to evaluate the
ability of this system, combined with a small furosemide dose, to
prevent contrast-induced acute kidney injury (MYTHOS, REMEDIAL II,
Dorval). In Dorval, the average urine rate was 620 ml/hr+/-400
ml/hr, MYTHOS 760 ml/hr, and REMEDIAL II 352 ml/hr+/-131 ml/hr.
These results have been replicated in thousands of cases where the
system has been used in clinical practice around the world.
[0054] The ability of this system to be used safely in patients
with acute decompensated heart failure was first established by Dr.
Albrecht Roemer and his team at St. Josefs-Hospital, Wiesbaden,
Germany. They used the system experimentally to manage the fluid
balance of a patient described to have "severely depressed EF" with
a rising serum creatinine level, which indicated that the patient
was developing acute kidney injury. Their goal was to maintain the
patient's intravascular fluid volume. They gave the patient a bolus
of 500 ml then second bolus of 500 ml. Only then did they give a
furosemide bolus. Urine output exceeded 300 ml/hr and dropped to
between 200-250 ml/hr, but remained within this range. The patient
did develop very mild edema, but it was not severe, and the patient
tolerated the therapy well. The patient's serum creatinine level
dropped, indicating resolution of the patient's acute kidney injury
and the patient recovered. This experience established that this
system could be used in patients with severely depressed ejection
fraction who are at very high risk of developing fluid overload and
induce the high urine rates that have shown to be protective of the
kidney while not causing fluid overload and severe pulmonary
edema.
[0055] The final support for this therapy comes from the clinical
experimental experience of Professor Shlomi Matetzky of Sheba
Medical Center. Prof. Matetzky and his team have used the system to
treat 8 patients at high risk of developing pulmonary edema.
[0056] In patients with chronic heart failure that presented with
acute heart failure and renal failure (or the risk of renal
failure), their clinical goal was to improve cardiac function,
which in turn improves renal function by improving renal blood
flow. In these patients, they would set the desired fluid balance
to -50 ml/hr and give the patient Furosemide to drive urine output.
In these patients they were able to take fluid off in a controlled
manner without the patient developing acute kidney injury or
becoming dehydrated or developing pulmonary edema.
[0057] They also used the concept of first inducing urine output
first by providing balanced or even positive fluid balance and once
the urine output has reached the desired level, setting the desired
fluid balance negative to allow the patient to slowly lose fluid.
This has been particularly effective in patients who presented with
intravascular dehydration and fluid overload.
All patients treated using the system in Prof. Matetzky's unit have
seen improvements in renal function and none have developed
pulmonary edema.
[0058] These three sets of data demonstrate that the system claimed
herein has the ability to safely be used in patients with fluid
overload or who are at high risk of developing fluid overload and
can be used to induce high urine rates and help those patients
slowly and safely lose excess fluid.
[0059] The below pseudo-code provides an implementation of the
fluid management software operable on controller 34:
[0060] Regardless of its mechanisms of action, hypertonic saline
therapy could be an additional useful clinical tool to force
diuresis and resolve fluid overload in CHF patients. It is not
currently used in routine clinical practice since many concerns are
raised in regard to safety and nursing labor involved in the
implementation of such therapy. Fluid retention in some patients
results from low sodium content of blood plasma and can be overcome
by the I.V. infusion of hypertonic saline. Sodium is a vital
electrolyte. Its excess or deficit in blood serum can cause
hypematremia or hyponatremia that can result in abnormal heart
rhythm, coma, seizures, and death. Administration of an effective
therapy with hypertonic saline requires careful monitoring and
tight controls. A system and a method have been developed to reduce
fluid overload and edema and force diuresis in patients with heart
failure and other conditions leading to fluid retention, that do
not respond to conventional drug therapy. The system and method
provides controlled infusion of an osmotic agent (i.e. hypertonic
saline) into the patient's I.V. that is safe and easy to use.
[0061] A novel patient infusion, monitoring and control system has
been developed that, in one embodiment, comprises:
[0062] A. A source of a solution of a blood compatible osmotic I.V.
infusible agent such as hypertonic saline,
[0063] B. An infusion pump and an I.V. set for controlled delivery
of the agent to the patient,
[0064] C. A biofeedback sensors connected to the patient that allow
monitoring and guiding of the therapy,
[0065] D. A microprocessor based controller responsive to the
biofeedback signals and is configured to adjust the infusion rate
of the pump based on the output of the biofeedback sensors
controlling the infusion of the osmotic agent.
[0066] In an embodiment that targets therapy of CHF patients, the
biofeedback component is comprised of a urine volume monitoring
device and a sensor monitoring sodium concentration in urine. The
infusion pump is designed for accurate volume delivery. The
concentration of sodium in the infusion fluid is known. This allows
the controller to calculate the amount of sodium and water
delivered to the patient (the "ins"). Urine monitoring measures the
amount of water and sodium excreted by the patient (the "outs").
The system balances (the "ins" and "outs") the total sodium amount
in the patient's body water and achieves the desired sodium
concentration in plasma. Optionally gradual controlled increase of
sodium concentration in serum can be achieved by: a) removal of
excess free water in urine, and b) net positive ("ins" over "outs")
addition of small amounts of sodium gradually over hours and days
of therapy. As a result, free water excretion is increased, while
sodium concentration in blood is maintained within the desired and
safe range or increased gradually and safely as desired.
[0067] It is understood that the osmotic agent can be a blood
compatible small molecule solute other than sodium, such as for
example urea. It is preferred that the osmotic agent is normally
present in the blood plasma and interstitial water and is excreted
by kidneys. It is also understood that the biofeedback may be a
physiologic parameter indicative of total or local (in a
compartment) body fluid volume such as intracranial pressure (ICP).
While the placement of an ICP monitor is invasive, the benefits of
ICP monitoring are felt to offset this factor in ICU patients with
severe brain trauma. Percutaneous devices (e.g., ventriculostomy
catheters) for use in monitoring ICP are commercially available in
a variety of styles and from a number of sources. The biofeedback
also may be a direct measurement of an osmotic agent and
particularly sodium concentration in blood performed using blood
chemistry sensors such as, for example, an i-STAT Device
manufactured by Abbot Health Care.
[0068] In one example, the control system includes a measuring or
monitoring sensor as part of or responsive to sodium in the urine
collection system and configured to determine the urine output from
the patient and a controller responsive to the meter. Typically,
the urine collection system includes a urinary catheter connected
to the urine collection chamber. In one embodiment, the meter is a
weighing mechanism for weighing urine in the collection chamber and
outputting a value corresponding to the weight of the urine to the
controller. The controller and the weighing mechanism can be
separate components or the controller and the weighing mechanism
may be integrated. Other types of meters which measure urine output
(e.g., volume or flow rate), however, are within the scope of this
invention.
[0069] Typically, the controller is programmed to determine the
rate of change of the urine weight, the rate of change of the urine
sodium concentration, to calculate a desired infusion rate based on
the rate of change of the urine weight, and to adjust the infusion
rate of the infusion pump based on the calculated desired infusion
rate to replace sodium lost in urine in a more concentrated
solution than urine sodium concentration. As a result net loss of
free water is achieved and blood serum sodium concentration is
increased, which is the desired goal of the therapy.
[0070] It is preferred that the controller subsystem includes a
user interface which is configured to allow the user to set a
desired serum concentration level achieved in a predetermined time
period. The user interface may also include a display indicating
the net water and sodium gain or loss, and a display indicating the
elapsed time. The user interface can be configured to allow the
user to set duration of replacement and to allow the user to set a
desired net fluid balance in hourly steps or continuous ramp rate.
The control subsystem may also include an alarm subsystem including
an air detector. The control subsystem is responsive to the air
detector and configured to stop the infusion pump if air exceeding
a specified amount is detected. The alarm subsystem may be
responsive to the urine collection system and configured to provide
an indication when the urine collection system has reached its
capacity. The alarm subsystem may also be responsive to the
infusion system and configured to provide an indication when the
infusion subsystem is low on infusion fluid.
[0071] The system may further include a diuretic administration
system and/or a blood chemistry sensor responsive to changes of
blood sodium concentration. The system may further include a
biosensor directly responding to intracranial pressure or the
interstitial fluid pressure in a body compartment where edema is
present.
[0072] A method of removing excess interstitial fluid from the
patient with fluid overload and edema in accordance with this
invention includes the steps of:
[0073] A. Monitoring a biological sensor responsive to a
physiologic variable;
[0074] B. Controlling the infusion pump based on the said
parameter; and
[0075] C. Infusing osmotic agent into the patient's blood.
[0076] The step of monitoring may comprise measuring the urine
output volume and composition. The step of measuring the urine
output may further include weighing the urine output by the
patient. Typically, the step of adjusting the infusion rate
includes determining the rate of excretion of sodium in the urine
of the urine output by the patient, calculating a desired infusion
rate based on the rate of change of the urine sodium, and adjusting
the infusion rate based on the calculated desired infusion
rate.
[0077] The method may further include the steps of setting a goal
(desired or target value) net sodium balance level (net loss or
gain) to be achieved by the control algorithm in a predetermined
time period, displaying the net fluid and sodium gain or loss,
displaying the elapsed time, setting a duration of therapy of the
patient, and/or detecting air during the step of infusing the
patient with the fluid containing an osmotic agent and
automatically stopping infusion if air exceeding a specified amount
if detected.
[0078] Presumably, as a result, diuresis of a patient is achieved
by removal of free water while increasing delivery of sodium to the
kidney. Other benefits to the patient, such as vasodilatation,
improved heart function, reduced hormone levels and improved kidney
function can be expected. Typically, for the proposed method,
sodium concentration in urine is substantially lower than in the
infused fluid. While the same absolute amount of sodium, thus
returned to the patient, may be the same, negative net balance
(loss) of water can be achieved. For example, urine Na
concentration can be 100 mEq/L and the infusion fluid sodium
concentration can be 300 mEq/L. A 1 liter of fluid lost in urine
can be replaced with 1/3 liter of I.V. fluid to achieve zero net
sodium balance. As a result, theoretically, 2/3 liter of free water
will be lost by the patient and no net loss of sodium will occur.
Concentration of sodium in blood plasma will increase in proportion
to the reduction of total body water. This example does not account
for patient's drinking or for the water lost by evaporation.
[0079] In some embodiments, bag 24, FIG. 1 is filled with an
osmotic agent infused during all three therapy time periods shown
in FIG. 3. In other embodiments, an osmotic agent is only infused
during the second therapy period. In some embodiments, the
controller of unit 34, FIG. 1 is responsive to a biofeedback sensor
associated with urine bag 52 and controls the infusion of the
osmotic agent as described above. In one example, when the sensor
detects a sodium concentration in the patient's urine or blood less
than a threshold, the infusion pump is controlled to automatically
infuse additional amounts of the osmotic agent until the sodium
concentration exceeds the threshold.
[0080] Although specific features of the invention are shown in
some drawings and not in others, this is for convenience only as
each feature may be combined with any or all of the other features
in accordance with the invention. The words "including",
"comprising", "having", and "with" as used herein are to be
interpreted broadly and comprehensively and are not limited to any
physical interconnection. Moreover, any embodiments disclosed in
the subject application are not to be taken as the only possible
embodiments.
[0081] In addition, any amendment presented during the prosecution
of the patent application for this patent is not a disclaimer of
any claim element presented in the application as filed: those
skilled in the art cannot reasonably be expected to draft a claim
that would literally encompass all possible equivalents, many
equivalents will be unforeseeable at the time of the amendment and
are beyond a fair interpretation of what is to be surrendered (if
anything), the rationale underlying the amendment may bear no more
than a tangential relation to many equivalents, and/or there are
many other reasons the applicant can not be expected to describe
certain insubstantial substitutes for any claim element
amended.
[0082] Other embodiments will occur to those skilled in the art and
are within the following claims.
* * * * *
References