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Estimated Dry Weight (EDW): aiming for accuracy. (Continuing Education).

One of the fundamental, yet most problematic, components of the hemodialysis prescription is the patient's estimated dry weight (EDW). In fact, the very phrase estimated dry weight reveals the problem. How does a clinician accurately estimate an ever-changing entity? How often is a new estimate needed? According to Gutch, Stoner, and Corea (1999), estimated dry weight is the "ideal postdialysis weight after the removal of all or most excess body fluid" (p. 114). Daugirdas, Blake, and Ing (2001) additionally stated, "The dry weight of each patient must be determined on a trial-and-error basis" (p. 140) and is ideally evaluated every 2 weeks. A thorough review of body fluid distribution along with fluid-related history, physical assessment, and laboratory findings serves to narrow what is often a shotgun approach to setting or adjusting EDW. The purpose of this article is to provide nephrology nurses with information to estimate dry weight with accuracy.

Body Fluid Compartments

A basic understanding of total body water and body fluid compartments is an integral foundation for determining the EDW. As a general rule, total body water is 60% of lean body weight for males and 50% of lean body weight for females (Rose & Post, 2001). The distinction between lean body weight and total body weight is especially important in regard to obese or fluid- overloaded patients, who are often encountered in the hemodialysis setting. There is little water in adipose tissue, placing obese patients at higher risk of dehydration from water loss (McCance & Huether, 1998). Likewise, it is important to note that older patients have decreased total body water related to increased body fat, decreased muscle mass, and decreased ability to regulate sodium and water balance (McCance & Huether, 1998). As with obese patients, elderly patients are at risk for dehydration related to pre-existing decreased total body water.

Total body water is contained within two broad compartments: intracellular fluid, which is the fluid inside cells, and extracellular, which is the fluid outside of cells. The extracellular fluid (ECF) is contained in the interstitial, the transcellular, and the intravascular spaces (Lancaster, 2001). Excess fluid that accumulates within the interstitial space is commonly referred to as edema (McCance & Huether, 1998). Transcellular fluids include "cerebrospinal, pericardial, pleural, peritoneal, synovial, and intraocular fluids; and sweat and digestive tract secretions" (Lancaster, 2001, p. 122). Intravascular fluid is the plasma component of blood (McCance & Huether, 1998). About 60% of the total body water is located in the intracellular compartment, and 40% is located in the extracellular compartment (Rose & Post, 2001). Of the 40% total body water located in the extracellular compartment, approximately 20% is in the plasma volume (Parker, 1998) (see Table 1). While fluid moves among compartments related to hydrostatic and osmotic pressures, only fluid contained in the intravascular space is available for removal during ultrafiltration (Ahmad, 1999).

As a basis for determining the intravascular fluid volume available for removal during dialysis, an important step in determining EDW, a quick overview of intravascular refill is warranted.

As fluid in the intravascular space is removed by ultrafiltration, the plasma fluid volume refills from the interstitial compartment (Ahmad, 1999).

The rate at which the plasma volume refills is affected by several factors. First, the plasma refill rate is affected by Starling forces, which means that pressures favoring movement of fluid into the vascular space must exceed pressures favoring movement into the interstitial space (McCance & Huether, 1998). Forces that decrease the rate of movement of water from the interstitial space into the plasma include decreased serum albumin, right-sided heart failure in which edema occurs as a consequence of increased pressure in the systemic venous circulation, increased capillary permeability, and increased oncotic pressure in the interstitium due to accumulation of protein as occurs with blockage of lymphatic vessels (Ahmad, 1999) (see Figure 1).

[FIGURE 1 OMITTED]

Second, osmolality affects the rate at which the plasma volume refills (Ahmad, 1999). If the fluid inside cells or in the interstitium has a higher osmolality than the plasma, fluid moves from the plasma into the interstitium or cells. Conversely, if the fluid in the interstitium or inside the cells has a lower osmolality than the plasma, fluid will move into the plasma (McCance & Huether, 1998). This principle is commonly used in hemodialysis when hypertonic solutions such as 23% saline, mannitol, or dextrose are given intravenously to increase plasma osmolality and enhance the plasma refill rate.

Methods of Determining EDW

A trial-and-error approach is most often used when determining EDW. This approach requires on-going assessment by astute nurses and input from patients to minimize inevitable errors. Information obtained from a thorough patient history, physical assessment, and laboratory value assessment can serve as a guide to the safe determination of EDW.

In recent years, technological advances have made possible the determination of EDW using a scientific, less error-prone method. One such advance involves the use of a blood volume monitor on the arterial blood line. The theory supporting this procedure is based on the increase in hematocrit that occurs with intravascular fluid removal. As the hematocrit rises, dialysis personnel are able to see the point at which plasma refill has slowed, enabling them to slow or stop ultrafiltration before the patient experiences hypotension (Daugirdas et al., 2001). The use of such technology may be cost-prohibitive in many hemodialysis units. Similarly, bioimpedance spectroscopy, which determines total body water and extracellular fluid volume, is of potential benefit (Fisch & Spiegel, 1996). This measurement involves passing a low voltage electrical current between an electrode on the patient's hand and another on the foot. Measurements are then processed via computer to determine fluid volume distribution (Wood, 1998). Again, the cost of such equipment may prohibit its routine use in many dialysis units.

Regardless of the method used to determine EDW, the process is on going and requires frequent assessment. Total body weight is not static and frequently changes independent of fluid intake. Thus, history and physical assessment indicators are helpful in determining an accurate EDW.

History and Physical Assessment

For the hemodialysis patient, the assessment can be divided into three segments-predialysis, intradialytic, and postdialysis.

Predialysis assessment. Vital signs are obtained before the start of each hemodialysis treatment. An elevated temperature may lead the clinician to suspect an increase in fluid loss caused by fever alone or with associated complaints, such as vomiting or diarrhea (Home & Swearingen, 1989; Rose & Post, 2001). Likewise, an elevation in heart rate coupled with a low blood pressure may signal volume depletion (McCance & Huether, 1998). Conversely, an elevated blood pressure is often a sign of fluid overload (Ahmad, 1999; Daugirdas et al., 2001).

In addition to assessing vital signs, patients are weighed before each treatment to measure interdialytic weight gain (IDWG). Generally, it is accepted practice for hemodialysis patients to restrict fluid intake to 1.0-1.5 liters of fluid per day. When the average daily fluid loss of 500-600 ml via the skin, respiratory, and GI tract is considered, this equals a net fluid gain of about 0.4-0.9 liters per day (Home & Swearingen, 1989). Ideally, one would expect patients to gain 1-2 liters of fluid over a 2-day interval and 2-3 liters over a 3-day interval. Yet, patients often gain far more. Nonetheless, it is helpful to note the amount of fluid gained. A relatively low IDWG may point to illness, while a large gain may point to excessive thirst, which needs to be investigated. Too often nurses fall into the habit of categorizing patients as noncompliant without investigating the reasons. Excessive thirst has many causes in hemodialysis patients, including increased plasma osmolality, as seen with elevated serum glucose levels in poorly controlled diabetics and after the administration of hypertonic agents; plasma volume depletion resulting from excessive ultrafiltration; release of angiotensin II in response to hypotension; and dryness of the mouth secondary to plasma volume depletion and/or many commonly used medications such as antihypertensives, diphenhydramine, over-the-counter cough and cold medications, and dialysis-related medications such as paracalcitol (Glutch, 2000; Guyton & Hall, 2000; Sandow, 2002). It has been estimated that there are over 400 different medications that can cause dry mouth (Khosla, 2002).

The next step in the predialysis treatment process generally involves questioning the patient about any problems encountered since the last hemodialysis treatment. Specific areas of questioning related to EDW that may be of benefit include presence of extreme weakness, fatigue, or dizziness, which may indicate hypotensive episode(s); quality of appetite, which may point to occult weight gain or loss; GI symptoms such as vomiting and diarrhea, which may indicate fluid volume deficit; and respiratory symptoms such as dyspnea or orthopnea, which may indicate fluid volume overload (Nissenson & Fine, 1993).

Once the above parameters have been addressed, it is time to move to the predialysis physical exam. Ideally this is completed before the start of hemodialysis, but may often be delayed until all patients on a shift have begun their dialysis procedures. Regardless of the time performed, it is the skillful dialysis nurse who performs a thorough, although quick, physical assessment on each patient.

An assessment of the patient's mucous membranes and skin may reveal helpful information about EDW. Mucous membranes that are dry and tacky suggest volume depletion as do parched lips and a furrowed tongue (Chambers, 1987). Likewise, dry skin with reduced turgor on the inner aspect of the forearm suggests volume depletion (Bickley & Hoekelman, 1999). Conversely, the presence of edema is suggestive of fluid volume overload (Guyton & Hall, 2000). While it is common practice to assess for periorbital and pretibial edema, it is important to note that fluid most often accumulates in dependent areas as a consequence of gravity (Levine, 1997). For non-ambulatory patients, a more helpful assessment includes assessing for edema in the presacral or thigh areas. Additionally, the presence of edema is often missed due to a hurried exam. Accurate assessment of edema involves pressing firmly into the skin with the thumb for 5-10 seconds and is usually graded on a four-point scale, with zero indicating absence of edema and 4+ indicating a 4 mm indentation (Bickley & Hoekelman, 1999; Lancaster, 2001). Non-pitting edema, which can be severe, is referred to as brawny edema and may be noted in patients with peripheral vascular disease (Bickley & Hoekelman, 1999) (see Figure 2).

[FIGURE 2 OMITTED]

Assessment of the cardiovascular system is the next logical step in assessing EDW. In the normovolemic patient, jugular veins are usually not visible; however, in the volume-overloaded patient, jugular veins are often distended and easily visible (Gutch et al., 1999). To assess the degree of distention, position the patient's upper body at a 30-45 degree elevation. Veins easily visible at this elevation signal fluid volume overload. Similarly, peripheral pulses may be strong and bounding in the presence of hypervolemia (Bickley & Hoekelman, 1999). Additionally, auscultation of heart sounds provides clues regarding hydration status. In the normovolemic patient, the heart sounds can usually be auscultated as two distinct sounds. The first sound, the [S.sub.1] or the "lub" component of the heart sound, is heard at the beginning of systole. The second sound, the [S.sub.2] or the "dub" component, is heard at the beginning of diastole (Bickley & Hoekelman, 1999). Additional heart sounds include [S.sub.3] and [S.sub.4]. The third heart sound, [S.sub.3], results from volume overload and increased ventricular preload. [S.sub.4], the fourth heart sound, caused by left ventricle stiffness, is a consequence of hypertension. In some patients who are both volume overloaded and hypertensive and have a rapid heart rate, the third and fourth heart sounds may merge into one sound, which is referred to as a summation gallop (Bickley & Hoekelman, 1999; White, 2001) (see Figure 3). While all heart sounds can be heard with the diaphragm of the stethoscope, the [S.sub.3], [S.sub.4], and summation gallop are best heard using the bell. Finally, capillary refill time longer than 2 seconds may indicate tissue hypoperfusion that can occur with hypovolemia (Maconochie, 1998).

[FIGURE 3 OMITTED]

The third component of the predialysis assessment relates to the lungs. Often dialysis nurses overlook lung assessment because patients "will tell me if they are short of breath." Patients often have become adjusted to the presence of dyspnea and may not consciously be aware of it. Assessing breath sounds each treatment, especially if the EDW is in question, can alert the nurse to the presence of crackles, rhonchi, and wheezes that signal fluid volume overload (Lancaster, 2001). The rate and depth of respirations are also important indicators of volume overload. With fluid accumulation in the lungs, the rate and depth of respiration increases in an effort to improve oxygenation (McCance & Huether, 1998). Similarly, retraction of accessory muscles in the neck may be observed in patients with respiratory distress due to fluid overload (Bickley & Hoekelman, 1999).

The fourth area of predialysis assessment relates to the gastrointestinal system. Patient complaints of nausea, vomiting, and diarrhea forewarn of potential volume depletion. Additionally, abdominal distention may indicate the presence of ascites and cause the clinician to question intravascular versus extravascular distribution of IDWG. Patients who frequently come to the dialysis unit with abdominal distention may warrant a review of liver function tests to assess for hepatic disease. In patients who have no other identifiable cause for ascites, hemodialysis-associated ascites, an event of unclear etiology that is managed with volume status control and adequate hemodialysis, may be the cause (Daugirdas et al., 2001).

Intradialytic assessment. In addition to predialysis vital signs, vital signs measured during the hemodialysis treatment are valuable indicators of fluid volume status. As stated earlier, an increasing heart rate coupled with decreasing blood pressure may herald volume depletion. While the patient may not have reached set EDW, these indicators can alert nurses to a possibly warranted change in the EDW. If EDW is believed to be accurate, signs of volume depletion often signal a plasma refill rate that is slower than the set ultrafiltration rate, necessitating a slower rate of ultrafiltration (Ahmad, 1999). Similarly, painful muscle cramps during treatment, which may persist after the treatment ends, are theorized to be caused by the depletion of intravascular volume (Parker, 1998). Finally, though not as frequent as in the past when acetate dialysate was standard, vomiting occurs in some patients. With the widespread use of bicarbonate dialysis, vomiting during hemodialysis is now most often associated with hypotension that can result from intravascular volume depletion (Lancaster, 2001). The occurrence of any of the above symptoms should prompt a re-evaluation of the established EDW as well as the ultrafiltration rate used to reach the EDW. Stable dialysis patients generally can tolerate an ultrafiltration rate of less than 20 ml/kg/hour (Ahmad, 1999). It is important to determine which patients are stable and which are not. A more conservative approach is to limit the ultrafiltration rate to 1% of the EDW per hour (Gutch et al., 1999).

Postdialysis assessment. Once the hemodialysis treatment is completed, the patient's weight is measured and compared with the predialysis weight to determine the total amount of fluid removed during treatment. Each kilogram of weight loss equals 1,000 ml fluid loss; each pound of weight loss equals 500 ml fluid loss. Weakness upon standing for measurement of weight is often a sign of orthostatic hypotension, which may be related to fluid volume deficit secondary to excessive ultrafiltration (McCance & Huether, 1998). Additionally, orthostatic hypotension may be caused by poor vasomotor tone as often occurs in patients with diabetes mellitus, and those patients may require a slightly higher EDW to maintain adequate blood pressure (Daugirdas et al., 2001).

Laboratory Data Assessment

Laboratory data important to the assessment of EDW include serum sodium, glucose, albumin, and hematocrit.

Sodium. Sodium, the major extracellular cation, is the primary determinant of extracellular osmolality and attracts water to the ECF space (Home & Swearingen, 1989). Normal serum sodium values are 135 mEq/L-145 mEq/L with some variance between laboratories. Hemodialysis patients often develop hyponatremia related to the inability to excrete excess water, causing an intravascular dilution of sodium (Levine, 1997). As discussed earlier, excessive thirst may accompany the use of many medications, leading to increased water intake and dilutional hyponatremia. Hypernatremia is usually indicative of dehydration rather than excess sodium intake (Daugirdas et al., 2001; Levine, 1997).

Glucose. Elevated serum glucose levels cause hyperosmolality of the extracellular fluid and causes water to move from the intracellular space to the ECF, which stimulates thirst (Nissenson & Fine, 1993). Therefore, diabetic patients with large IDWG require tight control of blood sugar before an accurate EDW can be determined.

Albumin. In hemodialysis patients, malnutrition is a persistent threat for most and a chronic condition for many. The importance of adequate protein intake to maintain albumin stores is underscored by studies linking low serum albumin levels to increased morbidity and mortality among hemodialysis patients (Schrier, 2000). One of the major functions of plasma albumin is to act as an osmotic agent, thereby holding fluid in the intravascular space (Home & Swearingen, 1989). A low albumin level consequently leads to the leakage of intravascular fluid into the interstitial spaces, which leads to visible edema. When attempting to remove excess fluid in a patient with a low serum albumin level, it is important to remember that only fluid in the intravascular compartment can be removed by ultrafiltration. The EDW for a hypoalbuminemic patient may need frequent adjustment as nutritional status changes.

Hematocrit. Anemia, like malnutrition, is an ever-present problem for the majority of hemodialysis patients for a myriad of reasons (Lancaster, 2001). Use of recombinant erythropoietin along with parenteral iron has markedly improved the management of this condition (Daugirdas et al., 2001). While an optimal hematocrit for patients with end-stage renal disease (ESRD) is not defined, the current recommendations for hematocrit level by the National Kidney Foundation's (NKF) Kidney Disease Outcomes Quality Initiative (K/DOQI) remains 33%-36% (NKF, 2002). In practice, even with optimal erythropoietin and iron dosing, it is often difficult to meet this goal for many reasons such as blood loss related to the dialysis procedure, occult blood loss, and shortened red-cell lifespan (Gutch et al., 1999). In contrast, the hematocrit, which is a measurement of the whole blood volume occupied by erythrocytes, rises when there is a reduction of plasma volume, as seen in dehydration (Home & Swearingen, 1989). In light of this, a markedly elevated hematocrit in a patient without polycystic kidney disease, a disease in which the hematocrit is often normal, warrants further investigation (Greenberg, 2001).

Additional Areas of Investigation

In addition to the above areas of assessment, several other factors are important in accurately estimating dry weight.

Treatment history. With computerized databases available in many outpatient dialysis facilities, cumulative records of recent dialysis sessions are usually readily available for review. Parameters such as average IDWG, average predialysis and postdialysis blood pressure, and average fluid volume administered each treatment are valuable guides. Patients gaining excessive amounts of fluid may require medication review to identify medications causing excessive thirst or diet investigation to evaluate sodium intake. Patients with elevated predialysis blood pressure may require a decrease in EDW. Conversely, patients with low postdialysis blood pressure who often require routine saline administration for blood pressure support may need an increase in EDW. Often, a simple notation or report to other staff members about problems encountered during treatment will aid in avoiding a repeated problem caused by an inaccurately set EDW.

Weights during hospitalization. In evaluating a patient recently admitted to a chronic hemodialysis unit, it is important to note that the initial EDW, set while hospitalized, is often a guess. Generally, patients who have experienced prolonged uremia are malnourished with resulting hypoalbuminemia, which may make ultrafiltration difficult or even disastrous (Schrier, 2000). After initiation of dialysis and resolution of uremia, appetite often improves and patients tend to gain tissue mass, requiring adjustment in EDW (Ahmad, 1999). Many, if not most, hospital weights are obtained with the patient wearing minimal clothing. The EDW should be then be assessed for changes related to the addition of clothing and shoes.

Holidays. It is the rare individual who survives the December holiday season without gaining weight! Dialysis patients are no different than most of us in that respect, and changes in EDW are often necessary related to seasonal variations, such as holiday-related weight gain (Daugirdas et al., 2001). Of equal importance is a decrease in appetite leading to weight loss, as may occur in the summer months.

Stressors. Stressors such as chronic illness, life-events, and bereavement are often associated with adverse changes in behavior such as poor eating habits (McCance & Huether, 1998). These changes may result in weight gain or loss, depending on the individual's coping pattern. Financial stressors may additionally cause inadequate intake related to the inability to afford nutritional food. In times of additional stress, evaluation of EDW is warranted.

Summary

Accurately estimating dry weight is a skill honed by practice. When adjusting dry weight, the clinician should consider all factors simultaneously. The physical assessment findings are correlated with vital signs, laboratory data, treatment history data, and information obtained from the patient. Only when all factors are considered in relation to each other is the target clearly visible (see Table 2).

Assessing and accurately determining the EDW is an often overlooked component of the hemodialysis regimen. In many cases, this is related to a lack of necessary information. Informed nurses are best prepared to accurately set and adjust the EDW--hitting the moving target with accuracy.
Table 1. Body Water Distribution Related to Body Weight

                         Volume of      Percentage of   Percentage of
Compartment           fluid in liters    body weight     body fluid

Total body water            42                               100
  Adult male
    Average build                            60
    Lean build                               70
    Obese                                    50
  Adult female
    Average build           50
    Lean build              60
    Obese                   42

Intracellular fluid         28               40               67

Extracellular fluid                          20               33
  Interstitial              11               15               26.4
  Intravascular              3                5                6.6
  Lymph                 negligible
  Transcellular         negligible

Table 2
Relation of Clinical Parameters to Estimated Dry Weight

CLINICAL PARAMETER                  POSSIBLY INDICATES

Vital Signs
* Increased heart rate with         * Plasma volume depletion from
  decreased blood pressure            incorrectly high EDW or UFR
                                      exceeding plasma refill rate
* Orthostatic hypotension           * Poor vasomotor tone/fluid volume
                                      deficit
* Fever                             * Fluid volume deficit secondary
                                      to increased insensible losses
* Elevated blood pressure           * Fluid overload
  pretreatment

Patient Complaints
* Fatigue, muscle cramps,           * Fluid volume deficit
  dizziness
* Interdialytic vomiting/diarrhea   * Fluid volume deficit secondary
                                      to increased losses
* Dyspnea/orthopnea                 * Fluid overload
* Intradialytic nausea/vomiting     * Fluid volume deficit

Physical Exam
* Dry mucous membranes              * Fluid volume deficit
* Poor skin turgor
* Capillary refill >2 seconds
* Edema                             * Fluid volume excess
* Jugular venous distension
* Bounding peripheral pulses
* Presence of [S.sub.3] heart
  sounds
* Rales, rhonchi, wheezes
* Increased rate and depth of
  respirations

Laboratory Data
* Elevated serum sodium             * Fluid volume deficit
* Decreased serum sodium            * Fluid volume excess
* Elevated glucose                  * Increased IDWG secondary to
                                      thirst
* Decreased albumin                 * Increased interstitial fluid,
                                      decreased intravascular fluid
* Elevated hematocrit               * Fluid volume deficit

Treatment History
* Frequent NS boluses for BP        * Fluid volume deficit
  support
* Excessive IDWG                    * Excessive thirst from
                                      medications and/or fluid volume
                                      deficit
* Routinely elevated predialysis    * Fluid volume overload
  BP
* Routinely low postdialysis BP     * Fluid volume deficit


Acknowledgement: The author wishes to thank Dr. Larry E. Lancaster for his editorial assistance.

References

Ahmad, S. (1999). Manual of clinical dialysis. London: Science Press.

Bickley, L.S., & Hoekelman, R.A. (1999). Bates' guide to physical examination and history taking (7th ed.). Philadelphia: Lippincott.

Chambers, J.K. (1987). Fluid and electrolyte problems in renal and urologic disorders. Nursing Clinics of North America, 22, 815-826.

Daugirdas, J.T., Blake, P.G., & Ing, T.S. (Eds.). (2001). Handbook of dialysis (3rd ed.). Philadelphia: Lippincott, Williams & Wilkins.

Fisch, B.J., & Spiegel, D.M. (1996). Assessment of excess fluid distribution in chronic hemodialysis patients using bioimpedance spectroscopy [Electronic version]. Kidney International 49, 1105-1109.

Glutch, J. (2000, December 18). Can fluoride help adults? Retrieved March 12, 2002, from www.intelihealth.com/ IH/ihtDNT/WSDNT000

Greenberg, A. (Ed.). (2001). Primer on kidney diseases (3rd ed.). San Diego, CA: Academic Press.

Gutch, C.F., Stoner, M.H., & Corea, A.L. (1999). Review of hemodialysis for nurses and dialysis personnel (6th ed.). St. Louis: Mosby.

Guyton, A.C., & Hall, J.E. (2000). Textbook of medical physiology (10th ed.). Philadelphia: W.B. Saunders Company.

Horne, M.M., & Swearingen, P.L. (1989). Pocket guide to fluids and electrolytes. St. Louis: Mosby.

Khosla, R. (2002). Dry mouth. Retrieved March 11, 2002, from www.members.rediff. com/drkhosla/drymouth.html

Lancaster, L.E. (Ed.). (2001). Core curriculum for nephrology nursing (4th ed.). Pitman, NJ: American Nephrology Nurses' Association.

Levine, D.Z. (1997). Caring for the renal patient (3rd ed.). Philadelphia: W.B. Saunders Company.

Maconochie, I. (1998). Capillary refill time in the field: It's enough to make you blush! [Electronic version]. Pre-hospital Immediate Care, 2, 95-96.

McCance, K.L., & Huether, S.E. (1998). Pathophysiology: The biologic basis for disease in adults and children (3rd ed.). St. Louis: Mosby.

National Kidney Foundation's Kidney Disease Outcomes Quality Initiative (K-DOQI). (2002, March). Clinical practice guidelines for anemia of chronic kidney disease: Update 2000. Retrieved March 12, 2002, from www.kidney. org/professionals/doqi/guidelines/ doqi_uptoc.html#an

Nissenson, A.R., & Fine, R.N. (1993). Dialysis therapy (2nd ed.). St. Louis: Mosby.

Parker, J. (Ed.). (1998). Contemporary nephrology nursing. Pitman, NJ: Anthony J. Jannetti, Inc.

Rose, B.D., & Post, T.W. (2001). Clinical physiology of acid-base and electrolyte disorders (5th ed.). New York: McGraw-Hill.

Sandow, N. (2002). The Internet drug index. Retrieved March 12, 2002, from www.rxlist.com

Schrier, R.W. (Ed.). (2000). Manual of nephrology (5th ed.). Philadelphia: Lippincott Williams & Wilkins.

White, K. (2001). Fast facts for adult critical care (3rd ed.). Mobile, AL: Kathy White Learning Systems.

Wood, M. (1998). Device may aid pregnancy monitoring. Retrieved March 10, 2002, from www.ars.usda.gov/is/pr/ 1998/980619.htm

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Estimated Dry Weight: Aiming for Accuracy

By Sheila Mitchell, BSN, RN, CNN

Posttest--1.4 Contact Hours

Posttest Questions

(See posttest instructions on the answer form, next page)

1. Which patient has the lowest total body water?

A. Middle aged male, average build.

B. Elderly obese male.

C. Middle aged female, average build.

D. Elderly obese female.

2. Elderly patients are at increased risk of dehydration secondary to

A. decreased total body water related to decreased body fat.

B. increased muscle mass.

C. loss of ability to regulate sodium and water.

D. increased sodium intake.

3. What fluid is available for removal with ultrafiltration during dialysis?

A. transcelluar fluid.

B. interstitial fluid.

C. extracellular fluid.

D. intravascular fluid.

4. R.J. is experiencing hypotension frequently during ultrafiltration on dialysis.

What factors decrease the rate of plasma volume refill rate?

A. decreased serum albumin.

B. decreased capillary permeability.

C. increased interstitial oncotic pressure.

D. increased intracellular osmolality.

5. J.T. has been on dialysis for 1 hour. You take his vital signs and note the following: pulse 128, blood pressure 98/60, respirations 16, temperature 97.2F. What should be your next action and why?

A. Increase machine temperature to prevent insensible losses

B. Place patient in Trendelenberg position to improve vasomotor tone

C. Decrease UF rate as you are exceeding the plasma refill rate.

D. Administer normal saline to increase serum osmolality.

6. You decide to continue ultrafiltration and treat J.T's hypotension. You employ the following principle: increased osmolality enhances plasma volume refill. What is your action?

A. decrease ultrafiltration rate (UFR)

B. administer hypertonic saline.

C. administer normal saline.

D. place patient in trendelenberg position.

7. H.H. continues to gain excessive amounts of weight in between dialysis treatments. H.H. states, "I am always so thirsty." Which of the following areas should you evaluate in your assessment of possible causes of H.H's thirst?

A. hyperglycemia only.

B. hyperglycemia and medications only.

C hyperglycemia, medications, and intradialytic hypotension only.

D. hyperglycemia, medications, and intradialytic hypotension and excessive intradialytic UF.

8. C.D., who is non-ambulatory, arrives in the wheelchair for her treatment. You are assigned to complete her pre-dialysis assessment. The best area to assess for edema would be

A. pre-tibial.

B. periorbital.

C. pre-sacral.

D. pedal.

9. The presence of S3 heart sound is often indicative of what clinical finding?

A. volume overload and increased ventricular pre-load.

B. atrial dilitation and arrythmia

C. left ventricular hypertrophy and hypertension.

D. hypovolemia and summation gallop.

10. You are assigned to complete the physical assessment predialysis on N.M. He is 0.5 kg over his estimated dry weight. He comes in complaining of decreased appetite. You determine the patient is volume overloaded with loss of estimated dry weight. N.M. is most likely to have what symptoms?

A. rales and rhonchi only

B. rales and rhonchi and edema only.

C. rales and rhonchi, edema, and bounding pulse.

D. rales and rhonchi, edema, bounding pulse and capillary refill < 2 seconds.

11. Stable dialysis patients can usually tolerate what limit on UFR?

A. 10 ml/kg/hr

B. 20 ml/kg/hr

C. 30 ml/kg/hr

D. 40 ml/kg/hr

12. You complete your pre-dialysis physical assessment of L.L. You decide that he is volume overloaded. To further validate your physical assessment findings you examine the laboratory data. What finding supports your assessment?

A. hypernatremia.

B. hyponatremia.

C. hyperglycemia.

D. hypoglycemia.

13. What factor(s) might cause you to initiate an assessment of the estimated dry weight?

A. patient stressors only.

B. patient stressors and holidays only.

C. patient stressors, holidays, following hospitalization only.

D. patient stressors, holidays, following hospitalization, and staff report of treatment-related problems.

ANSWER FORM

Estimated Dry Weight: Aiming for Accuracy

By Sheila Mitchell, BSN, RN, CNN

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Telephone: --

ANNA Member -- Yes -- No CNN -- Yes -- No

Source of Article: [] Journal [] ANNA Web site (ANNAlink)

Note: If you wish to keep the journal intact, you may photocopy the answer sheet or access this posttest at www.annanurse.org

Posttest Answer Grid

Please circle your answer choice:

1. a b c d

2. a b c d

3. a b c d

4. a b c d

5. a b c d

6. a b c d

7. a b c d

8. a b c d

9. a b c d

10. a b c d

11. a b c d

12. a b c d

13. a b c d

Goal: The nephrology nurse will be able to estimate dry weight with accuracy.
                                              Strongly      Strongly
Evaluation                                    disagree       agree

1. The objectives were related to the goal.      1   2   3   4   5

2. Objectives were met

   a. Describe basic principles of total         1   2   3   4   5
      body water and body fluid
      compartments.

   b. Discuss factors affecting                  1   2   3   4   5
      intravascular refill.

   c. Explain the steps in assessment            1   2   3   4   5
      of estimated dry weight.

3. The instructions were clear to complete       1   2   3   4   5
   this activity.

4. I would rate the learning level of this       1   2   3   4   5
   self-study as basic.

5. Minutes required to complete self-study,
   including the posttest:                       -- minutes


Comments --

What topics do you need: --

Sheila Mitchell, BSN, RN, CNN, is an Inservice Coordinator, Fresenius Medical Care, Jackson, MS. At the time this article was written, she was a student in the Acute Care Nurse Practitioner Program at University of Mississippi School of Nursing, Jackson, MS. She is a member of the Magnolia Chapter of ANNA.
COPYRIGHT 2002 Jannetti Publications, Inc.
No portion of this article can be reproduced without the express written permission from the copyright holder.
Copyright 2002 Gale, Cengage Learning. All rights reserved.

Article Details
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Author:Mitchell, Sheila
Publication:Nephrology Nursing Journal
Date:Oct 1, 2002
Words:5484
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