In-service Training Manual Section 2: Theory Crit-Line III TQA
Managing the Vicious Cycle of Fluid Removal The CRIT-LINE Monitor  is a CQI Outcome Management Tool that allows clinicians...
The test tube represents the volume of blood in the intravascular compartment as broken down into its two major components...
FLUID DYNAMICS OF THE BODY The dialysis process removes fluid directly from the intravascular space, this space is then re...
THE GUYTON CURVE The Guyton curve illustrates the approximate relationship between extracellular fluid volume and blood vo...
On the far right , the curve describes Edema as a region with as much as 40 liters of extracellular fluid.  If the pre-dia...
THE “B” PROFILE 0 1 2 3 4 5 6 7 8 5 10 15 20 25 30 35 40 0 Adapted from Guyton, AC:  Textbook of Medical Physiology, 1991,...
As shown here, the fluid removal falls below the Guyton curve into the “C  region” of the graph as the vascular compartmen...
Once the staff has established a B profile for a patient, it is important to continue to use the Crit Line monitor on the ...
Each dialysis patient has a critical blood volume level where symptoms begin.  This illustration depicts a patient who had...
“ FLYING THE CURVE” <ul><li>The HCT Threshold is independent of UFR, time of dialysis, and session to session patient and ...
0 1 2 3 4 Time (hours) 0 10 -10 -20 -30 BV Change (%) 1 2 Refill:  An Indicator of Over-Hydration   Evaluating and adjusti...
BLOOD VOLUME PROFILES REVIEW Blood Volume Profiles A-C   display the effect of hemodialysis on the intravascular space, me...
HYPOXEMIA DURING HEMODIALYSIS <ul><li>Hypoxemia can be a significant complication of hemodialysis causing intradialytic mo...
HYPOXEMIA DURING HEMODIALYSIS <ul><li>As many as 26% of patients drop their O 2   Sat 2-8% in the first hour of dialysis; ...
HYPOTENSION-- NOT PREDICTED BY BP CUFF Currently, clinicians are relying on symptoms like a drop in blood pressure to dete...
%BV  CASE STUDY - “A” OVERLOADED PATIENT PROFILE The graph above is a blood volume profile printed from a CRIT-LINE Monit...
CASE STUDY - “B” OR IDEAL PATIENT PROFILE In this treatment the nurse removed 3.5 liters.  There is a gentle decline in bl...
CASE STUDY - INTERVENING USING THE CRIT-LINE This patient run demonstrates how the CRIT-LINE Monitor is typically used to ...
CASE STUDY - VOLUME OVERLOADED/HYPOTENSIVE PATIENT A volume overloaded, hypotensive patient can be difficult to dialyze.  ...
CASE STUDY - INTERVENING WITH TRENDELENBERG Due to the rapid decrease in blood volume (minus 15 % in the first hour), the ...
CASE STUDY - MORE FLUID REMOVED/DRY WEIGHT CHECK In this treatment the original fluid removal goal was 2.4 liters.  Using ...
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Section 2 -- Theory Crit-Line III TQA

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Section 2 -- Theory Crit-Line III TQA

  1. 1. In-service Training Manual Section 2: Theory Crit-Line III TQA
  2. 2. 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.
  3. 3. 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. 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. HEMATOCRIT AND BLOOD VOLUME RELATIONSHIP UF MIN UF MIN UF MIN Total Blood Volume (BV) Red Cell Volume (RCV) Test tube represents circulating blood volume Hct = RCV BV Plasma Volume 34 32 30 28 26 -10 -5 0 -15 -20 -25 % BV  Hct Time (hours) 0 1 2 3 4 Hct = X 100 RCV BV
  4. 4. FLUID DYNAMICS OF THE BODY 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. Three Compartment Model Toxins Fluid Intra-cellular Space Extra-cellular Space Intra-Vascular Space Dialysate Flow 17 Liters 5 Liters Toxins Fluid Toxins Fluid Circulating Blood Volume 23 Liters
  5. 5. THE GUYTON CURVE 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. 0 1 2 3 4 5 6 7 8 5 10 15 20 25 30 35 40 0 Adapted from Guyton, AC: Textbook of Medical Physiology, 1991, pg.324 Normal Death Edema Blood Volume (liters) Extracellular Fluid Volume (liters)
  6. 6. On the far right , the curve describes Edema as a region with as much as 40 liters of extracellular fluid. If the pre-dialysis fluid status of an ESRD patient falls within this region it is possible to remove a significant amount of fluid from the patient and still be in the edematous region on the Guyton curve. In this case the patient would leave still having two extra liters of fluid in their vascular space (blood volume). An “A” profile suggests that the patient is not at the correct dry weight and that excess fluid must be removed before the correct dry weight is reached. It also illustrates that ultrafiltration and plasma refilling were equivalent during treatment. Patients who remains in the “A” region will eventually experience complications such as CHF, LVH, pulmonary edema and hypertension. 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.” THE “A” PROFILE 0 1 2 3 4 5 6 7 8 5 10 15 20 25 30 35 40 0 Adapted from Guyton, AC: Textbook of Medical Physiology, 1991, pg.324 Normal Death A Edema Blood Volume (liters) Extracellular Fluid Volume (liters) TIME 03:25 HCT 31.2 BV  0.2 SAT 98 -20 0 -10 5 BV 
  7. 7. THE “B” PROFILE 0 1 2 3 4 5 6 7 8 5 10 15 20 25 30 35 40 0 Adapted from Guyton, AC: Textbook of Medical Physiology, 1991, pg.324 Normal Death B Blood Volume (liters) Extracellular Fluid Volume (liters) The blue shaded area on the Guyton curve represents the region of the curve where ideal fluid removal takes place. Past the knee of the curve, the downward slope suggests that fluid is being simultaneously withdrawn from both the vascular and cellular spaces. This segment is called the “B” region. Since the ultimate goal of dialysis is to approximate normal kidney function the most effective dialysis takes place when patients are in this region. TIME 03:25 HCT 34.7 BV  -17.3 SAT 94 -20 0 -10 5 BV  A “B” profile may be described by a gentle slope of approximately -3% to -8% BV change per hour, and is without significant flat areas or discontinuities. “B” profiles suggest treatments with consistent fluid removal without intervention or complications.
  8. 8. As shown here, the fluid removal falls below the Guyton curve into the “C region” of the graph as the vascular compartment alone sustains the fluid removal. The corresponding BV profile slope becomes quite steep (greater than -8% BV change per hour) as the vascular volume is depleted too rapidly. 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. THE “C” PROFILE TIME 01:37 HCT 34.7 BV  -17.3 SAT 94 -20 0 -10 5 BV  TIME 2:28 HCT 37.4 BV  -18.4 SAT 91 -20 0 -10 5 BV  TIME 03:25 HCT 34.7 BV  -12.6 SAT 94 -20 0 -10 5 BV  0 1 2 3 4 5 6 7 8 5 10 15 20 25 30 35 40 0 Adapted from Guyton, AC: Textbook of Medical Physiology, 1991, pg.324 Normal Death Hypovolemia C Blood Volume (liters) Extracellular Fluid Volume (liters) Shift Due to: UFR Na+ Temp Posture
  9. 9. 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. Treatment to Treatment Stability C B A Patient Stability?
  10. 10. 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 Thursday. After a weekend of fluid intake they presented themselves with a starting hematocrit of 30, yet their Crash CRIT was 39 during both dialysis sessions. 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. This profile depicts a patient who began dialysis with a 33 hematocrit and became symptomatic at a hematocrit of approximately 40.7 three consecutive times during the treatment. Now the staff will know in subsequent treatment that whenever the hematocrit reaches 40.7 this patient will become symptomatic. Three consecutive “Crashes” at a Hct of 40.7 HYPOVOLEMIA AND THE HCT THRESHOLD (CRASH CRIT) 34 30 Thursday Tuesday 39 HCT (start) Crash CRIT Beginning fluid status does not affect the Crash CRIT TIME 03:25 HCT 37.6 BV  -11.7 SAT 94 -20 0 -10 5 BV 
  11. 11. “ FLYING THE CURVE” <ul><li>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. </li></ul><ul><li>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. </li></ul>%BV  Time (hr) 5 -10 0 -20 1 2 3 4 “ Hct Line ” or Threshold 50% More Fluid
  12. 12. 0 1 2 3 4 Time (hours) 0 10 -10 -20 -30 BV Change (%) 1 2 Refill: An Indicator of Over-Hydration 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. TRACKING AND ACHIEVING DRY WEIGHTS
  13. 13. BLOOD VOLUME PROFILES REVIEW Blood Volume Profiles A-C display the effect of hemodialysis on the intravascular space, measured in %BV  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 B, associated with segment B of the Guyton Curve, illustrates a gradual decrease in blood volume with no required nurse intervention. 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. 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. BV Profile A BV Profile B BV Profile C
  14. 14. HYPOXEMIA DURING HEMODIALYSIS <ul><li>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. </li></ul><ul><li>(See diagram below) </li></ul>Figure 7: Tissue Ischemia Blocks the release of norepinephrine from sympathetic nerve terminals Blocks the release of norepinephrine from sympathetic nerve terminals Releases adenosine Releases adenosine Thus, hypotension can perpetuate itself through the release of adenosine and its effects. This tissue ischemia effect maybe the reason that anemic patients are prone to hypotension. Thus, hypotension can perpetuate itself through the release of adenosine and its effects. This tissue ischemia effect maybe the reason that anemic patients are prone to hypotension. TISSUE ISCHEMIA TISSUE ISCHEMIA TISSUE ISCHEMIA
  15. 15. HYPOXEMIA DURING HEMODIALYSIS <ul><li>As many as 26% of patients drop their O 2 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) </li></ul><ul><li>The Crit-Line Monitor provides a continuous, real time O 2 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 (SaO 2 ) via the fistula/ graft or a mixed venous saturation (SvO2) via a CVC line. </li></ul><ul><li>Hypoxemia generally occurs at SaO 2 levels of <90% (COPD patients may exhibit readings in the 80’s). Acceptable SvO 2 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. </li></ul><ul><li>If the O2 saturation or HCT fall below the above parameters, suggesting hypoxemia, clinical protocol for administering oxygen should be followed. </li></ul>0 1 2 3 4 Time (hours) 80 85 90 95 O2 Saturation Sleep
  16. 16. HYPOTENSION-- NOT PREDICTED BY BP CUFF 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. Time (hours) % Change in Blood Volume Systolic Blood Pressure             0 1 2 3 4 0 10 -10 -20 -30 0 25 50 75 100 125 150    UF Off (Hypotension) UFR = 1428 ml/hr Figure 1 0 20 40 60 80 100 120 140 160 Systolic Blood Pressure         0 1 2 3 4 Time (hours) 0 5 -10 -20 UF Off (Cramps) UFR = 1522 ml/hr    % Change in Blood Volume Figure 2
  17. 17. %BV  CASE STUDY - “A” OVERLOADED PATIENT PROFILE 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. -20 -10 0 5 Time (hr) 1 2 3 4 5
  18. 18. CASE STUDY - “B” OR IDEAL PATIENT PROFILE 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. Time (hr) %BV  1 2 3 4 -20 -10 0 5
  19. 19. CASE STUDY - INTERVENING USING THE CRIT-LINE 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. 13 800 per hour 1 2 3 4 -20 -10 0 5 Time (hr) %BV  1000 1200 1500 3.2 L Removed UF OFF 1500 & patient in TB 4.2L Removed UF OFF Rebound 800 per hour Goal: 3.2 L. Removed: 4.7 L .
  20. 20. CASE STUDY - VOLUME OVERLOADED/HYPOTENSIVE PATIENT 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. Time (hr) %BV  1 2 3 4 -20 -10 0 5 98/54 92/40 112/64 7.7L Removed UF ON MIN 118/70 8.0 L Removed 7.0 L Goal 92/50 MAX UFR
  21. 21. CASE STUDY - INTERVENING WITH TRENDELENBERG 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. Time (hr) %BV  1 2 3 4 -20 -10 0 5 Sitting Trendelenberg Sitting Trendelenberg Sitting UF Vol = 4300 ml UFR = 1146 ml/hr
  22. 22. CASE STUDY - MORE FLUID REMOVED/DRY WEIGHT CHECK 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. 1 2 3 4 -20 -10 0 5 Time (hr) %BV  UF ON MIN

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