In-service Training Manual Section 2 Theory Crit-Line III TQA

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					In-service Training Manual
     Section 2: Theory
     Crit-Line III TQA




        Updated January 2006   1
              Managing the Vicious Cycle of Fluid Removal


The CRIT-LINE Monitor is a CQI Outcome Management Tool that allows
clinicians to safely and consistently dialyze their patients to their ideal dry
weights. The CRIT-LINE Monitor provides a window into the
intravascular compartment of the body by monitoring a patient’s blood
volume change in real time during dialysis.
 Now for the first time, the clinician can accurately determine how well a
patient’s plasma refilling rate is keeping up with the ultra filtration rate of
the dialysis machine. Having this information in real time enables
proactive intervention based on the amount of fluid the patient’s body is
able shift into the intravascular space during any given treatment session.
If the fluid removal is too rapid the clinician can intervene before
hypovolemic or hypotensive symptoms occur. If the fluid removal rate is
too slow, the clinician can intervene by increasing the ultra filtration rate to
successfully achieve the patient’s dry weight. The CRIT-LINE Monitor
can help clinicians determine the effectiveness of an intervention based on
the instantaneous feedback it gives.
 The CRIT-LINE Monitor is a tool the clinician can utilize to improve the
clinical outcome of every dialysis patient giving them increased accuracy
and control of the fluid removal process.
 The case studies towards the back of this manual are printouts from actual
patient runs monitored with the CRIT-LINE Monitor. These are common
scenarios found in dialysis centers across the country, but because each
patient and each dialysis treatment session is unique they should not be
considered as protocols for intervention. The CRIT-LINE Monitor
provides additional insight about the dialysis process, which should be
used to supplement the information already known about the patient in
establishing the most beneficial care plan. The CRIT-LINE Monitor must
always be used in conjunction with the patient’s existing clinical
information before altering a dialysis treatment.



                          Updated January 2006                                 2
HEMATOCRIT AND BLOOD VOLUME RELATIONSHIP
                                               Test tube represents
                                               circulating blood volume



                                               Plasma
                                               Volume
                 Total Blood                                          RCV
                 Volume (BV)                                  Hct =
                                                                      BV

                                               Red Cell
                                               Volume
                                                (RCV)


The test tube represents the volume of blood in the intravascular compartment as broken
down into its two major components: the red cell volume and the plasma volume. Total
blood volume is the sum of these two.
Hct is defined as the ratio of the red cell volume to the total blood volume and is a
fundamental vascular marker. Because red blood cells are too large to pass through the
dialyzer they remain constant during dialysis.


                                                                        34
                                                                        32
                                                                             Hct
                                                                        30
                                                                        28
                      0                 Hct = RCV X 100                 26
                                              BV
                      -5
                    -10
                % BVD
                    -15
                     -20              UF MIN   UF MIN     UF MIN
                     -25
                           0      1           2           3            4
                                       Time (hours)


Because red blood cell volume remains constant, a rise in hematocrit during dialysis
represents a reduction in plasma volume. Therefore, hematocrit and blood volume have
an inverse relationship as illustrated by these profiles. The top profile illustrates the
change in hematocrit during a dialysis treatment session. Below is the “BV” profile that
indicates the corresponding change that occurs in the blood volume of a patient. By
monitoring the hematocrit in real time, the CRIT-LINE calculates the percent change in
blood volume in the intravascular space and then displays this information graphically.
                               Updated January 2006                                      3
FLUID DYNAMICS OF THE BODY




              Three Compartment Model

               Intra-
               cellular       Extra-    Circulating
               Space          cellular Blood Volume
                              Space
                                        Intra-
                                        Vascular
                                        Space                        Toxins

                     Toxins          Toxins                           Fluid

                      Fluid          Fluid
                                                                   Dialysate Flow
             23 Liters        17 Liters       5 Liters



The dialysis process removes fluid directly from the intravascular space, this space is
then refilled with fluid from the extracellular space (the tissue). Prior to the CRIT-LINE
Monitor there was no way to measure how well the patient’s plasma refilling rate kept
up with the ultrafiltration rate of the dialysis machine. The plasma refilling rate (PRR) is
the body’s ability to shift fluid from the extracellular space into the blood (intravascular
space). Now, with CRIT-LINE one can directly measure the blood volume change in
the intravascular space, and thereby determine how well the body is refilling this
compartment during dialysis. If dialysis progresses faster than the bodies ability to refill
(the ultra-filtration rate is greater than the plasma refilling rate), the volume of the
intravascular space will be reduced and will be displayed on the CRIT-LINE as a
reduction in blood volume.




                               Updated January 2006                                        4
                 THE GUYTON CURVE



                        8

                                                                            Edema
                        7
Blood Volume (liters)




                        6

                        5
                                          Normal

                        4

                        3
                                Death
                        2

                        1                                                  Adapted from Guyton, AC:
                                                          Textbook of Medical Physiology, 1991, pg.324
                        0
                            0   5        10       15      20        25         30          35            40

                                        Extracellular Fluid Volume (liters)

           The Guyton curve illustrates the approximate relationship between extracellular fluid
           volume and blood volume, and demonstrates a limit to blood volume as fluid levels
           continue to increase past a normal range. The average 70 kg adult has approximately 5
           liters of blood volume in his/her intravascular space. This corresponds to a normal
           extracellular fluid level of about 17 liters on Guyton’s curve. According to Guyton, as
           fluid volume is added or removed, the body will distribute its fluid load according to this
           curve. In the case of fluid being added and not removed (as is the case with pre-dialysis
           patients), once a maximum vascular capacity of approximately 7 liters is reached, all
           additional fluid expands into the extracellular space. Note: Guyton’s curve is an
           approximation of fluid dynamics and is patient specific.




                                              Updated January 2006                                        5
                        THE “A” PROFILE



                        8                                                                    On the far right , the curve
                                                                        Edema                describes Edema as a region
                        7                                                                    with as much as 40 liters of
Blood Volume (liters)




                                                                        A
                        6
                                                                                             extracellular fluid. If the
                                                                                             pre-dialysis fluid status of an
                                         Normal
                        5                                                                    ESRD patient falls within
                        4                                                                    this region it is possible to
                                                                                             remove a significant amount
                        3                                                                    of fluid from the patient and
                                Death
                        2
                                                                                             still be in the edematous
                                                                                             region on the Guyton curve.
                        1                                     Adapted from Guyton, AC:
                                                                                             In this case the patient would
                                             Textbook of Medical Physiology, 1991, pg.324
                        0                                                                    leave still having two extra
                            0   5       10        15     20      25      30      35     40   liters of fluid in their
                                      Extracellular Fluid Volume (liters)                    vascular space (blood
                                                                                             volume).


                        A patient who is fluid “Overloaded” or in the edematous region on the Guyton curve will
                        typically display a positive blood volume slope, a flat-line, or a BV profile slower than
                        -3% per hour: an “A” profile. Accordingly, this region on the Guyton curve is called the
                        “A region.”


                        5                                                                    An “A” profile suggests that
                                                                                             the patient is not at the correct
                        0                                                                    dry weight and that excess
                                                                                             fluid must be removed before
BVD                                                                                          the correct dry weight is
                                                                                             reached. It also illustrates that
                                                                                             ultrafiltration and plasma
   -10                                                                                       refilling were equivalent
                                                                                             during treatment. Patients
                                                                                             who remains in the “A”
                                                                                             region will eventually
  -20                                                                                        experience complications such
    TIME 03:25                          HCT 31.2              BVD 0.2         SAT 98         as CHF, LVH, pulmonary
                                                                                             edema and hypertension.



                                                          Updated January 2006                                           6
                        THE “B” PROFILE




                                                                                              The blue shaded area on the
                        8                                                                     Guyton curve represents the
                                                                                              region of the curve where ideal
                        7                                                                     fluid removal takes place. Past
Blood Volume (liters)




                        6                              B                                      the knee of the curve, the
                                                                                              downward slope suggests that
                                          Normal
                        5                                                                     fluid is being simultaneously
                                                                                              withdrawn from both the
                        4                                                                     vascular and cellular spaces.
                        3                                                                     This segment is called the “B”
                                Death                                                         region. Since the ultimate goal
                        2                                                                     of dialysis is to approximate
                                                               Adapted from Guyton, AC:       normal kidney function the
                        1                                                                     most effective dialysis takes
                                              Textbook of Medical Physiology, 1991, pg.324
                        0                                                                     place when patients are in this
                            0   5        10       15       20     25     30      35      40   region.
                                        Extracellular Fluid Volume (liters)




                        5                                                                     A “B” profile may be described by
                                                                                              a gentle slope of approximately
                        0                                                                     -3% to -8% BV change per hour,
                                                                                              and is without significant flat areas
                                                                                              or discontinuities. “B” profiles
BVD                                                                                           suggest treatments with consistent
                                                                                              fluid removal without intervention
    -10                                                                                       or complications.




    -20
      TIME 03:25                        HCT 34.7           BVD -17.3          SAT 94




                                                           Updated January 2006                                              7
                          THE “C” PROFILE


                          8                                                                                As shown here, the fluid removal
                                                                                                           falls below the Guyton curve into
                                                                                                           the “C region” of the graph as the
  Blood Volume (liters)




                          7
                                                                                                           vascular compartment alone
                          6
                                                                                                           sustains the fluid removal. The
                          5                Normal                                  Shift
                                                                                            UFR            corresponding BV profile slope
                                                                                            Na+
                                                                                    Due                    becomes quite steep (greater than
                                                                                            Temp
                          4                                        C                 to:                   -8% BV change per hour) as the
                                                                                            Posture
                                                           Hypovolemia                                     vascular volume is depleted too
                          3
                                   Death                                                                   rapidly.
                          2
                          1                                        Adapted from Guyton, AC:
                                                  Textbook of Medical Physiology, 1991, pg.324
                          0
                              0    5         10       15      20       25     30           35         40
                                       Extracellular Fluid Volume (liters)


                          A “C” profile, which can begin anywhere along the Guyton curve, describes a dialysis
                          session in which the patient ultimately experiences some type of intradialytic morbidity
                          such as lightheadedness, nausea, vomiting, cramping or hypotension; a condition often
                          called “crashing.” This usually requires intervention and discontinuation of the dialysis
                          session. Most “C” profiles are characterized by trace discontinuities. The three profiles
                          below show “C” profiles at different stages during a treatment.

                                                                                            5

                                                                                            0

                                                                                       BVD

                                                                                           -10
                                                       5

                                                       0

                                                    BVD                                    -20
                                                                                            TIME 01:37     HCT 34.7   BVD -17.3    SAT 94
                                                     -10
        5

        0

BVD                                                  -20
                                                       TIME 2:28   HCT 37.4   BVD -18.4          SAT 91
 -10



 -20
  TIME 03:25                      HCT 34.7    BVD -12.6      SAT 94

                                                              Updated January 2006                                                      8
Treatment to Treatment Stability


                                          Patient Stability?
                        C
    Profile A, B or C




                        B




                        A
                            1   2 3   4   5 6   7   8   9 10 11 12 13 14 15 16 17 18 19 20 21

                                                    Treatment Days




Once the staff has established a B profile for a patient, it is important to continue to use
the Crit Line monitor on the patient to ensure that they get the same profile consistently
treatment to treatment. The graph above represents a patient who was followed for 21
treatment sessions with no intervention based upon information from the CRIT-LINE . It
also illustrates how patients can present themselves differently from treatment to
treatment. There are several reasons why patients do present themselves differently such
as sodium intake, their general diet, fluid intake, and blood pressure medication, to name
a few. The CRIT-LINE provides a real-time window into the vascular space to assist the
clinician in achieving optimal fluid removal each treatment regardless of patient
presentation.




                                            Updated January 2006                                9
  HYPOVOLEMIA AND THE HCT THRESHOLD (CRASH CRIT)

                                                                           Each dialysis patient has a
                                                                           critical blood volume level
                                                                           where symptoms begin.
                                                                           This illustration depicts a
                                                                           patient who had a starting
                                                                           hematocrit of 34 on
                             30                                            Thursday. After a weekend
            34                HCT (start)                                  of fluid intake they presented
                                                     39                    themselves with a starting
                                                                           hematocrit of 30, yet their
                                                       Crash CRIT
                                                                           Crash CRIT was 39 during
                                                                           both dialysis sessions.
                                                     Beginning fluid
                                                     status does not
                                                     affect the Crash
                                                     CRIT


  Thursday         Tuesday
  The critical blood volume level in a patient can be identified at the absolute hematocrit at
  which the symptoms occur in the patient. This is called the HCT Threshold or “crash-
  crit”. The HCT Threshold, which marks the onset of hypovolemia and related morbidity,
  is very patient specific. But once this level has been identified for any individual patient,
  it can serve as a marker where the symptoms will occur in subsequent treatments. By
  setting a HCT LIMIT (or alarm line called the “crit-line”) on the Crit-Line Monitor 1-2
  HCT units below the identified HCT Threshold, and reducing the UFR to minimum at
  this point, intradialytic morbid events can be prevented. If the HCT Threshold is
  unknown, the HCT LIMIT should be set approximately 15% above the starting HCT.

  5                                                                     This profile depicts a patient
                                                                        who began dialysis with a 33
  0                                                                     hematocrit and became
                                                                        symptomatic at a hematocrit of
BVD                                                                     approximately 40.7 three
                                                                        consecutive times during the
-10                                                                     treatment. Now the staff will
                                                                        know in subsequent treatment
                                                                        that whenever the hematocrit
                                                                        reaches 40.7 this patient will
-20                                                                     become symptomatic.
  TIME 03:25       HCT 37.6        BVD -11.7          SAT 94



                 Three consecutive “Crashes” at a Hct of 40.7
                                  Updated January 2006                                             10
   “FLYING THE CURVE”




       5


       0
%BVD




  -10                       50% More
                              Fluid


                                           “Hct Line ” or Threshold
  -20
                           1                   2                    3                  4
                                        Time (hr)


   The HCT Threshold is independent of UFR, time of dialysis, and session to session
   patient and treatment variations (i.e. weight gains/losses, inaccurate weight assessment,
   temperature, constipation, blood glucose or sodium levels, etc.). The slope of the
   profile does not predict when morbidity may occur. Conversely, the absolute HCT can
   be used to define a singular endpoint-a patient specific threshold value. Bringing blood
   volume down to a safe minimum early (avoiding the HCT Threshold) , and keeping it
   there throughout the session creates the highest possible mobilization of tissue fluid
   possible over the longest period. By setting a HCT Limit on the Crit-Line Monitor, 1-2
   HCT units below the identified HCT Threshold and reducing the UFR to minimum ( at
   or below 400 mls per hour) , intradialytic morbid events may be prevented. The HCT
   Threshold will remain constant as long as the patient’s RBC mass remains relatively
   constant between treatments and should be reassessed approximately every 3-4 weeks.
   The picture above depicts a %BV change of approximately -18% in the first hour of
   treatment. Subsequently, when the patient’s HCT reached the HCT Limit, the UFR was
   reduced to minimum and was maintained at this level. No refill was noted indicating
   that the patient is at or near their ideal dry weight.

                                  Updated January 2006                                     11
  TRACKING AND ACHIEVING DRY WEIGHTS


                      Refill: An Indicator of Over-Hydration
                      10
      BV Change (%)




                       0

                      -10
                                                                                 1
                      -20

                      -30                                                         2
                            0      1                2                 3                 4
                                           Time (hours)
Evaluating and adjusting a patient’s dry weight is difficult because there is no way to “look”
into the extracellular space to see just how much fluid is there. Although Crit-Line
monitoring gives no indication of extracellular fluid status, it does provide a “window” into
the intravascular space. With the ability to determine the change in blood volume, the
clinician can determine how effective the patient’s body is transferring fluid from the
extracellular space to the intravascular space. Knowing this can assist the clinician in
achieving ideal dry weights gradually over several treatments. This is done by using what
Hema Metrics refers to as a “dry weight check.” Near the end of treatment or when the fluid
removal goal is achieved, the clinician can turn the UFR to minimum (at or below 400 mls
per hour) for 15 to 20 minutes to determine if extra fluid from the extracellular space will
transfer into the intravascular space. The CRIT-LINE blood volume profile will then display
either refill as shown by the number 1 profile above or, display little or no refill as shown
by the number 2 profile. If there is a pronounced refill, this is an indication that the patient
is still over-hydrated, that more fluid could be removed and that the patient is not at their
ideal dry weight. It is important to conduct several dry weight checks on the same patient
over several treatments to gradually dialyze the patient to their ideal dry weight.

If a patient crashes, and after turning the UFR on minimum there is a pronounced refill as in
1, this is an indicator that the UF rate was too high and that more fluid could be removed. If
a patient crashes and there is little or no refill, as in 2, after turning the UF to minimum, this
is an indicator that the patient is at or near an ideal dry weight.

                                 Updated January 2006                                        12
  BLOOD VOLUME PROFILES REVIEW



Blood Volume Profiles A-C display the effect of hemodialysis on the intravascular
space, measured in %BVD change over a typical 3-4 hour dialysis treatment session.



BV Profile A, associated with segment A of the
Guyton Curve, is typical of the fluid overloaded
patient                                                BV Profile A




BV Profile B, associated with segment B of the
Guyton Curve, illustrates a gradual decrease in
blood volume with no required nurse intervention.
                                                       BV Profile B




BV Profile C, associated with segment C of the
Guyton Curve, illustrates a very rapid depletion in
blood volume resulting in an early “sign-off” or
“Crash,” with nurse intervention.                      BV Profile C


  There are three basic types of blood volume profiles, “A” profiles, “B” profiles and “C”
  profiles. The “A” or the fluid overloaded profile indicates no change in blood volume and
  no change in hematocrit during dialysis. This indicates a patient is still on the right side
  of the Guyton Curve and not at their correct dry weight. The plasma refilling rate (PRR)
  was the same as the ultrafiltration rate (UFR). The “B” or ideal profile has a 5% per hour
  decline in blood volume while experiencing no morbidity. This indicates the patient is
  moving down the “knee of the Guyton curve” approaching a normal blood volume level.
  The “C” or crash profile indicates that the BV level in the intravascular space was
  reduced to an unsafe level. The patient experienced hypovolemic symptoms due to this
  volume depletion in his intravascular space. In this instance, even though the patient
  experienced a “crash’ or intradialytic morbidity, the refill noted suggests that more fluid
  could be removed. Just because a patient crashes, it does not mean they are at their dry
  weight.

                                 Updated January 2006                                     13
HYPOXEMIA DURING HEMODIALYSIS



Hypoxemia can be a significant complication of hemodialysis causing
intradialytic morbid events such as hypotension, cramping, as well as
periods of tissue ischemia. This has been attributed to the release of
adenosine. Tissue ischemia causes the release of adenosine which
subsequently blocks the release of norepinephrine from the sympathetic
nerve terminals and has intrinsic vasodilator properties. Thus, hypotension
can perpetuate itself through the release of adenosine and its effects.
 (See diagram below)

                                     TISSUE ISCHEMIA
                                     TISSUE ISCHEMIA




                              Releases adenosine
                              Releases adenosine




              Thus, hypotension
               Thus, hypotension
                can perpetuate
                 can perpetuate
               itself through the
                itself through the
                   release of
                    release of
              adenosine and its
               adenosine and its
                                                   Blocks the release of
                                                   Blocks the release of
                   effects.
                    effects.
                                                  norepinephrine
                                                  norepinephrine          from
                                                                           from
                  This tissue
                   This tissue
               ischemia effect
                ischemia effect
              maybe the reason
              maybe the reason
                                                   sympathetic
                                                   sympathetic          nerve
                                                                        nerve
                that anemic          Figure 7: Tissue Ischemia
                 that anemic                               terminals
              patients are prone
                                                            terminals
               patients are prone
               to hypotension.
                to hypotension.




                               Updated January 2006                               14
HYPOXEMIA DURING HEMODIALYSIS

     As many as 26% of patients drop their O2 Sat 2-8% in the first hour of
dialysis; 56% of patients experience at least one episode of hypoxemia.
Sleep apnea occurs in approximately 50 to 70% of all treatments. With the
chronic hemodialysis cardiac mortality rate of approximately 50%, any
additional cardiac stress has to be viewed as detrimental. The incidence of
intradialytic hypoxic events may be underestimated as an additional causal
factor of chronic deterioration of the cardiovascular system. (See Sleep
Apnea profile below)
                             95
             O2 Saturation




                             90


                             85            Sleep


                             80
                               0     1       2          3   4
                                         Time (hours)
  The Crit-Line Monitor provides a continuous, real time O2 Sat that is
insensitive to poor skin perfusion, peripheral vasoconstriction, hypotension,
hypovolemia, multiple previous accesses, low body temperature, and other
dialysis related factors that cause errors in pulse oximeters. The Crit-Line
Monitor measures the true arterial saturation (SaO2 ) via the fistula/ graft or
a mixed venous saturation (SvO2) via a CVC line.
Hypoxemia generally occurs at SaO2 levels of <90% (COPD patients may
exhibit readings in the 80’s). Acceptable SvO2 ranges between 60-80%.
Hypoxemia may present with a drop of 5-10% below the patient’s previous
value. Hypoxemia may also occur with severe anemia (HCT <25%).
Oxygen Saturation is the percent to which hemoglobin (HGB) is filled with
O2. The more anemic the patient is, (the lower the HCT) the fewer total
HGB molecules they have. This causes the total amount of O2 available to
the tissues to be low, even though the O2 sat appears normal. O2 saturation
must be interpreted in relationship to the degree of anemia.
 If the O2 saturation or HCT fall below the above parameters, suggesting
hypoxemia, clinical protocol for administering oxygen should be followed.
                                   Updated January 2006                     15
HYPOTENSION-- NOT PREDICTED BY BP CUFF
                             10                                                                               150
                                   
  % Change in Blood Volume


                                          




                                                                                                                     Systolic Blood Pressure
                                                                                                   
                                                        
                                                                                                              125
                              0
                                                                                                             100
                             -10                                                                             75
                                                                              UF Off
                                                                           (Hypotension)
                             -20                                                                              50

                                                                                                              25
                             -30
                                   UFR = 1428 ml/hr
                                                                                                               0
                                   0          1           2                                       3          4
                                                    Time (hours)                                             Figure 1
                                                          % Change in Blood Volume




                                                                                      5                                                                                160




                                                                                                                                                                             Systolic Blood Pressure
                                                                                                                                                                       140
                                                                                                                                            
                                                                                      0
                                                                                                                                                                     120
                                                                                                                                                                       100
                                                                                                                                                                       80
                                                                                     -10                                                                               60
                                                                                                                                                                       40
                                                                                                                                                        UF Off         20
                                                                                          UFR = 1522 ml/hr                                              (Cramps)
                                                                                     -20                                                                               0
                                                                                         0          1               2                                       3      4
                                                                                                          Time (hours)                                             Figure 2



Currently, clinicians are relying on symptoms like a drop in blood pressure to determine
when a patient has had a potentially dangerous reduction in their vascular volume. There are
two inherent problems with relying on blood pressure as an indicator of hypotension and
hypovolemia. The two graphs above illustrate these problems. The dots represent systolic
blood pressure measurements that were taken every fifteen minutes, and the profile
represents change in blood volume. In figure 1 the blood pressure did not drop until after
the patient had experienced symptoms. Not allowing the clinician a chance for prevention.
However, the blood volume profile did show a rapid decrease in the blood volume and that
the patient could no longer tolerate the current Ultrafiltration rate. In the second figure, the
patient experienced hypovolemic symptoms with no corresponding change in blood pressure
again not allowing for detection or prevention by the clinician. As illustrated the blood
pressure may not drop until after symptoms occur, or the blood pressure may not drop at all.
Using the information on the Crit-Line, the clinician can now see how well a patient is
plasma refilling and can take proactive steps to prevent crashing.

                                                                                     Updated January 2006                                                                        16
   CASE STUDY - “A” OVERLOADED PATIENT PROFILE




       5


       0


%BVD
   -10




   -20
                      1                2               3                4               5

                                       Time (hr)


   The graph above is a blood volume profile printed from a CRIT-LINE Monitor after
   monitoring a patient on dialysis for 4 hours 20 minutes. During treatment, 4 liters of fluid
   were removed, however, the patient’s PRR was slightly faster than the UFR, as depicted
   by the positive trend in blood volume. This is an indication that at the completion of
   dialysis the patient still had extra fluid in the intravascular space and extra fluid in the
   extracellular space. This graph represents an “A” or fluid overloaded profile, which is
   typical of a patient who is not at their ideal dry weight.




                                 Updated January 2006                                       17
   CASE STUDY - “B” OR IDEAL PATIENT PROFILE




       5

       0

%BVD


   -10



   -20

                              1                   2                    3                   4

                                            Time (hr)


       In this treatment the nurse removed 3.5 liters. There is a gentle decline in blood volume
       (recommended blood volume change is approximately minus 5% per hour), and the
       patient was asymptomatic. This profile indicates that the prescribed fluid removal not
       only removed extracellular fluid but also “dipped” into the patients intravascular space
       reducing the blood volume in the intravascular space to the normal level on the Guyton
       Curve. Dialyzing a patient to their ideal dry weight reduces the risk of CHF, LVH, and
       hypertension. The ultrafiltration rate (UFR) was slightly faster than the patient’s plasma
       refilling rate (PRR). This is the ideal profile for this patient.




                                    Updated January 2006                                       18
   CASE STUDY - INTERVENING USING THE CRIT-LINE




        5


        0
%BVD



       -10




       -20
                            1                   2                   3                   4
                                           Time (hr)     Goal: 3.2 L. Removed: 4.7 L.


   This patient run demonstrates how the CRIT-LINE Monitor is typically used to guide
   nurse intervention during a dialysis treatment. The patient’s original goal was 3.2 liters.
   Using feedback from the CRIT-LINE Monitor, the UFR was increased from 800 ml/hour
   to 1500 ml/hr to obtain a gradual (5% per hour) decrease in blood volume. After 2 hours
   20 minutes the original goal of 3.2 liters was reached. A dry weight check was performed
   to see if the patient’s blood volume would rebound. As shown in the above graph, refill
   occurred indicating there was additional fluid in the extracellular space. The nurse then
   decided to challenge the patient’s dry weight by turning the UFR back to 500 ml/hr and
   placing the patient in Trendelenberg. The nurse removed an additional liter of fluid and
   turned the UFR to minimum again, resulting in another plasma refill. The UFR was
   turned back on to 800 ml/hr and an additional 0.5 liters were removed. The ability to see
   how the intravascular space is being refilled is critical during aggressive or challenging
   treatments.




                                 Updated January 2006                                       19
   CASE STUDY - VOLUME OVERLOADED/HYPOTENSIVE PATIENT




         5
 7.0 L
 Goal
         0
%BVD                                                                               8.0 L
                                                                                   Removed


       -10




       -20
                            1                   2                   3                   4

                                         Time (hr)


   A volume overloaded, hypotensive patient can be difficult to dialyze. Additional fluid in
   the intravascular space of a dialysis patient can be one of the primary causes of elevated
   blood pressure. However, if the patient becomes too overloaded the extra volume may
   overcome the bodies compensatory mechanisms and cause the patient to have a low pre-
   dialysis blood pressure and/or pressure drop during dialysis.
   The patient in the example above had a low starting blood pressure due to extreme
   volume overload. In addition, the patient would consistently experience a blood pressure
   drop 10 to 15 minutes into the treatment. In response to the pressure dropping the staff
   was forced to discontinue ultrafiltration and infuse saline. These measures would fail to
   bring the blood pressure up and as a result the fluid removal goal was never achieved.
   Monitoring the patient with the CRIT-LINE Monitor the nurse could see the patient’s
   blood volume level was actually increasing during dialysis. Realizing that a positive
   trend in blood volume would cause a further drop in blood pressure, the nurse increased
   the fluid foal from 7 liters to 8.8 liters. This caused the blood volume to gradually
   decrease to a normal level allowing the compensatory mechanisms of the body to return
   the blood pressure to a more normal level. The original fluid goal was exceeded by 1
   liter.
                                 Updated January 2006                                       20
CASE STUDY - INTERVENING WITH TRENDELENBERG




       5
           UFR = 1146 ml/hr

       0
                     Sitting
%BVD                                      Sitting


     -10
                                                                       Sitting



     -20
                         Trendelenberg          Trendelenberg              UF Vol = 4300 ml
                               1                    2                  3                     4

                                            Time (hr)


Due to the rapid decrease in blood volume (minus 15 % in the first hour), the nurse
intervened
by placing the patient in Trendelenberg. Without changing the ultrafiltration rate, this
caused
a rebound effect , helping the body plasma refill more quickly. The refill suggests that
there is additional extracellular fluid, however the patient’s body was unable to transfer
this fluid into the intravascular space fast enough to compensate for the UFR.
Trendelenberg assisted the patient in shifting fluids to the intravascular space. Upon
returning to sitting position, the graph began to drop off rapidly again. As the graph
started to rapidly drop again, the nurse put the patient back in Trendelenberg position.
This action flattened the blood volume profile. The nurse was able to manipulate this
treatment using only Trendelenberg position to achieve the UF goal with no symptoms.




                                   Updated January 2006                                  21
CASE STUDY - MORE FLUID REMOVED/DRY WEIGHT CHECK




        5


        0
%BVD                                                          UF ON
                                                               MIN


       -10



       -20
                               1                     2                    3                    4

                                             Time (hr)


In this treatment the original fluid removal goal was 2.4 liters. Using the CRIT-LINE
instrument as a guide to increase the ultrafiltration rate, an additional 2.8 liters of fluid
were removed. By seeing the blood volume change in real time the nurse was able to
challenge the patient safely. If the patient had been unable to keep up with the more
aggressive fluid removal the blood volume profile would have started to drop off
dramatically (PRR was less than the UFR) and the nurse would have reduced the goal
before the patient experienced hypovolemic symptoms. At the end of the treatment she
performed a “Dry Weight Check” by reducing the UFR to minimum. If fluid is no longer
being ultrafiltrated, any fluid above normal that is left in the extracellular space will refill
the intravascular space. As stated previously, an ideal dialysis session would remove any
fluid in the extracellular space that is above the normal point on the Guyton curve. It
would also bring the intravascular volume to normal levels. However, as shown in the
above graph, there is a “rebound” in blood volume, refill, which indicated there is more
fluid to be removed. A patient is typically not at their ideal dry weight if their fluid
removal goal was achieved and a dry weight check indicates more fluid could have been
removed.

                                Updated January 2006                                         22