CHAPTER 8: Fluid and Electrolytes
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1.A client develops interstitial edema as a result of decreased: A) Vascular volume
B) Hydrostatic pressure
C) Capillary permeability
D) Colloidal osmotic pressure
Edema can be defined as palpable swelling produced by an increased interstitial fluid
volume. The physiologic mechanisms that contribute to edema formation include factors that (1) increase capillary filtration (hydrostatic) pressure, (2) decrease the capillary colloid osmotic pressure, (3) increase capillary permeability, or (4) produce obstruction to lymph flow.
2.A client has been receiving intravenous normal saline at a rate of 125 mL/hour since her surgery 2 days earlier. As a result, she has developed an increase in vascular volume and edema. Which of the following phenomena accounts for this client's edema?
A) Obstruction of lymph flow
B) Increased capillary permeability
C) Decreased capillary colloidal osmotic pressure
D) Increased capillary filtration pressure
An increase in vascular volume results in an increase in capillary filtration pressure. Consequently, movement of vascular fluid into the interstitial spaces increases and edema ensues. An increase in vascular volume does not directly result in obstruction of lymph flow, increased capillary permeability, or decreased capillary colloidal osmotic pressure.
3.The most reliable method for measuring body water or fluid volume increase is by assessing:
A) Tissue turgor
B) Intake and output
C) Body weight change D) Serum sodium levels Ans: C
Daily weights are a reliable index of water volume gain (1 L of water weighs 2.2 pounds). Daily weight measurements taken at the same time each day with the same amount of
clothing provide a useful index of water gain due to edema. When an unbalanced distribution of body water exists in the tissues and organs, assessment of surface skin tissue turgor will be inaccurate. Measurement of renal output is unreliable because fluid retention may be a compensatory response, or the renal system may be dysfunctional. Serum sodium levels are affected by multiple variables other than body water volume.
4.A client with a diagnosis of liver cirrhosis secondary to alcohol abuse has a distended abdomen as a result of fluid accumulation in his peritoneal cavity (ascites). Which of the following pathophysiologic processes contributes to this third spacing?
A) Abnormal increase in transcellular fluid volume
B) Increased capillary colloidal osmotic pressure
D) Impaired hormonal control of fluid volume
Third spacing represents the loss or trapping of extracellular fluid (ECF) in the transcellular space and a consequent increase in transcellular fluid volume. The serous cavities are part of the transcellular compartment located in strategic body areas where there is continual movement of body structures—the pericardial sac, the peritoneal cavity, and the pleural cavity. Polydipsia and increased fluid intake alone are insufficient to cause third spacing, and increased capillary colloidal osmotic pressure would result in increased intracellular fluid (ICF). The etiology of third spacing does not normally include alterations in hormonal control of fluid balance.
5.A 2-week-old infant (full-term at birth) is admitted to the pediatrics unit with “spitting up large amounts of formula” and diarrhea. The infant has developed a weak suck reflex. Which of the following statements about total body water (TBW) is accurate in this situation?
A) About 52% of the infants' weight accounts for the amount of water in their body. B) Because of the infants' higher fat ratio, one should anticipate an increased TBW to
as high as 90%.
C) Most full-term infants have a TBW of approximately 75% due to their high metabolic rate.
D) Most of an infant's TBW remains in the ICF compartment, so they should be able to transfer needed water into the ECF space.
Infants normally have more TBW than older children or adults. TBW constitutes
approximately 75% to 80% of body weight in full-term infants and an even greater percentage in premature infants. In males, the TBW decreases in the elderly population to approximately 52% TBW. Obesity decreases TBW, with levels as low as 30% to 40% of body weight in adults. Infants have more than half of their TBW in their ECF compartment, as compared to adults.
6.A client diagnosed with schizophrenia has been admitted to the emergency department (ED) after ingesting more than 2 gallons of water in one sitting. Which of the following pathophysiologic processes may result from the sudden water gain?
B) Water movement from the extracellular to the intracellular compartment
C) Syndrome of inappropriate secretion of ADH (SIADH)
D) Isotonic fluid excess in the extracellular fluid compartment
Excess water ingestion coupled with impaired water excretion (or rapid ingestion at a
rate that exceeds renal excretion) in persons with psychogenic polydipsia can lead to water intoxication (hyponatremia). A disproportionate gain of water with no accompanying gain in sodium results in the movement of water from the extracellular to the intracellular compartment. Hyponatremia accompanies this process. Because of the lack of sodium increase, accumulated fluid is hypotonic, not isotonic. SIADH is not a consequence of excess water intake.
7.A nurse caring for a client with a diagnosis of diabetes insipidus (DI) should prioritize the close monitoring of which of the following electrolyte levels?
The high water intake and high urine output that characterize diabetes insipidus create
a risk of sodium imbalance. DI may present with hypernatremia and dehydration, especially in persons without free access to water, or with damage to the hypothalamic thirst center and altered thirst sensation.
8.The syndrome of inappropriate antidiuretic hormone (SIADH) is characterized by: A) Increased osmolality level of 360 mOsm/kg
B) Excessive thirst with fluid intake of 7000 mL/day
C) Copious dilute urination with output of 5000 mL/day
D) Low serum sodium level of 122 mEq/L Ans: D
SIADH results from a failure of the negative feedback system that regulates the release and inhibition of antidiuretic hormone (ADH). ADH secretion continues even when serum osmolality is decreased, causing water retention and dilutional hyponatremia. Diabetes insipidus, deficiency or decreased response to ADH, is characterized by
increased serum osmolality, excessive thirst, and polyuria. Urine output decreases in
SIADH despite adequate or increased fluid intake.
9.In isotonic fluid volume deficit, changes in total body water are accompanied by: A) Intravascular hypotonicity
B) Increased intravascular water
C) Increases in intracellular sodium D) Proportionate losses of sodium Ans: D
Isotonic fluid volume deficit causes a proportionate loss of sodium and water. Hypotonicity results from water retention or sodium loss. Increased intravascular water causes sodium to move into the cell excessively.
10.A client with a history of heart and kidney failure is brought to the emergency department. Upon assessment/diagnosis, it is determined the client is in decompensated heart failure. Of the following assessment findings, which are associated with excess intracellular water? Select all that apply.
C) Hyperactive deep tendon reflexes
E) Firm, rubbery tissue when palpating lower extremities
Ans: A, B, D
Hyponatremia is usually defined as a serum sodium concentration of less than 135 mEq/L. Muscle cramps, weakness, and fatigue reflect the effects of hyponatremia on skeletal muscle function and are often early signs of hyponatremia. The cells of the brain and nervous system are the most seriously affected by increases in intracellular water. Symptoms include apathy, lethargy, and headache, which can progress to disorientation, confusion, gross motor weakness, and depression of deep tendon reflexes. Seizures and coma occur when serum sodium levels reach extremely low levels. Hypovolemia, third
spacing (maldistribution of body fluid), and dehydration are associated with hypernatremia and/or hypertonicity.
11.Which of the following assessments should be prioritized in the care of a client who is being treated for a serum potassium level of 2.7 mEq/L?
A) Detailed fluid balance monitoring checking for pitting edema
B) Arterial blood gases looking for respiratory alkalosis
C) Cardiac monitoring looking for prolonged PR interval and flattening of the T wave
D) Monitoring of hemoglobin levels and oxygen saturation
The most serious effects of hypokalemia are on the heart, a fact that necessitates frequent electrocardiography or cardiac telemetry. Hypokalemia produces a decrease in the resting membrane potential, causing prolongation of the PR interval. It also prolongs the rate of ventricular repolarization, causing depression of the ST segment, flattening
of the T wave, and appearance of a prominent U wave. This supersedes the importance
of fluid balance monitoring, arterial blood gases, oxygen saturation, or hemoglobin levels.
12.Of the following clients, which would be at highest risk for developing hyperkalemia? A) A male admitted for acute renal failure following a drug overdose
B) A client diagnosed with an ischemic stroke with multiple sensory and motor deficits
C) An elderly client experiencing severe vomiting and diarrhea as a result of influenza
D) A postsurgical client whose thyroidectomy resulted in the loss of some of the parathyroid glands
There are three main causes of hyperkalemia: (1) decreased renal elimination; (2) a shift
in potassium from the ICF to ECF compartment; and (3) excessively rapid rate of administration. The most common cause of serum potassium excess is decreased renal function. Stroke does not typically have a direct influence on potassium levels, whereas vomiting and diarrhea can precipitate hypokalemia. Loss of the parathyroid influences calcium, not potassium, levels.
13.A heart failure client has gotten confused and took too many of his “water pills” (diuretics). On admission, his serum potassium level was 2.6 mEq/L. Of the following assessments, which correlate to this hypokalemia finding? Select all that apply.
D) Paresthesia with numbness of the lips/mouth
E) ECG showing short runs of ventricular fibrillation
Ans: A, B, D
The manifestations of hypokalemia include alterations in neuromuscular, gastrointestinal, renal, and cardiovascular function. There are numerous signs and symptoms associated with gastrointestinal function, including anorexia, nausea, and vomiting. Atony of the gastrointestinal smooth muscle can cause constipation, abdominal distention, and, in severe hypokalemia, paralytic ileus. Urine output and
plasma osmolality are increased; urine specific gravity is decreased; and complaints of polyuria, nocturia, and thirst are common. The most serious effects of hypokalemia are on the heart. The first symptom associated with hyperkalemia typically is paresthesia (a feeling of numbness and tingling). Hyperkalemia results in prolongation of the PR interval; widening of the QRS complex with no change in its configuration; and decreased amplitude, widening, and eventual disappearance of the P wave. The heart rate may be slow. Ventricular fibrillation and cardiac arrest are terminal events.
14.A client has been admitted for deterioration of her renal function due to chronic renal failure. Her admission K+ level is 7.8 mEq/L. The nurse would expect to see which of the following abnormalities on her telemetry (ECG) strip? Select all that apply.
A) Tachycardia (fast rate) with frequent early ventricular beats (PVCs) B) Prolonged PR interval with widening of the QRS complex
C) Ventricular fibrillation
D) Atrial flutter with a 2:1 conduction ratio
Ans: B, C
Hyperkalemia decreases membrane excitability, producing a delay in atrial and ventricular depolarization, and it increases the rate of ventricular repolarization. If serum K+ levels continue to rise (above 6 mEq/L), there is a prolongation of the PR interval; widening of the QRS complex with no change in its configuration; and decreased amplitude and widening and eventual disappearance of the P wave. The heart rate may be slow. Ventricular fibrillation and cardiac arrest are terminal events.
15.Hypoparathyroidism causes hypocalcemia by: A) Increasing serum magnesium
B) Increasing phosphate excretion
C) Blocking release of calcium from bone D) Blocking action of intestinal vitamin D Ans: C
The most common causes of hypocalcemia are abnormal losses of calcium by the
kidney, impaired ability to mobilize calcium from bone due to hypoparathyroidism, and increased protein binding or chelation such that greater proportions of calcium are in the nonionized form. Magnesium deficiency inhibits PTH release and impairs PTH action on bone resorption. Phosphate and calcium are inversely related, and PTH does not control phosphate excretion. PTH does not exert control of vitamin D action in the intestine, but elevated vitamin D levels can suppress PTH release.
16.A female client with a history of chronic renal failure has a total serum calcium level of
7.9 mg/dL. While performing an assessment, the nurse should focus on which of the following clinical manifestations associated with this calcium level?
A) Complaints of shortness of breath on exertion with decreased oxygen saturation levels
B) Difficulty arousing the client and noticing she is disoriented to time and place
C) Heart rate of 120 beats/minute associated with diaphoresis (sweaty)
D) Intermittent muscle spasms and complaints of numbness around her mouth
Spasms and numbness are characteristic of hypocalcemia. Respiratory effects, tachycardia, and diaphoresis are not associated with low calcium levels, whereas decreased level of consciousness can be indicative of hypercalcemia.
17.An elderly client is admitted with elevated magnesium level related to a history of renal insufficiency and excess use of antacids and laxatives containing magnesium. On admission assessment, the nurse notes which clinical manifestations that correlate to hypermagnesemia? Select all that apply.
B) Blood pressure 180/90
C) Tetanic muscle contractions
D) Muscle weakness causing shallow breathing
E) Paresthesia of the lips
Ans: A, D Feedback:
The signs and symptoms occur only when serum magnesium levels exceed 4.0 mg/dL. Hypermagnesemia affects neuromuscular and cardiovascular function. Increased levels of magnesium cause hyporeflexia and muscle weakness. Blood pressure is decreased, and the ECG shows an increase in the PR interval, a shortening of the QT interval, T- wave abnormalities, and prolongation of the QRS and PR intervals. Severe hypermagnesemia is associated with muscle and respiratory paralysis, complete heart block, and cardiac arrest. Signs of magnesium deficiency are not usually apparent until the serum magnesium is less than 1.0 mEq/L. Hypomagnesemia is characterized by an increase in neuromuscular excitability as evidenced by hyperactive deep tendon reflexes, paresthesias (i.e., numbness, pricking, tingling sensation), muscle fasciculations, and tetanic muscle contractions.
18.Magnesium is important for the overall function of the body because of its direct role in: A) Cell membrane permeability
B) Somatic cell growth control
C) Sodium and tonicity regulation
D) DNA replication and transcription
Magnesium is essential to all reactions that require ATP, for every step related to
replication and transcription of DNA, and for translation of messenger RNA. Magnesium does not have a direct role in controlling the growth of cells, extracellular tonicity and sodium balance, or permeability of the cell surface.
19.Which of the following scenarios place the client at a high risk for developing hypoparathyroidism and require close supervision for assessing for development of muscle cramps, carpopedal spasm, convulsions, and paresthesia in the hands and feet? Select all that apply.
A) A neck cancer client returning from OR after having a radical neck dissection
B) A hyperthyroid client experiencing a “thyroid storm” requiring urgent
C) A client with seizure experiencing some anoxic deficits and memory loss
D) A client with a history of human papillomavirus (HPV) in the uvula
Ans: A, B
Hypoparathyroidism reflects deficient PTH secretion, resulting in low serum levels of
ionized calcium. PTH deficiency may occur because of a congenital absence of all of the parathyroid glands or because of an acquired disorder due to inadvertent removal or irreversible damage to the glands during thyroidectomy, parathyroidectomy, or radical neck dissection for cancer. Seizures or history of HPV is not associated with this disorder.
20.As other mechanisms prepare to respond to a pH imbalance, immediate buffering is a result of increased:
A) Intracellular albumin
B) Hydrogen/potassium binding
C) Sodium/phosphate anion absorption D) Bicarbonate/carbonic acid regulation Ans: D
The bicarbonate buffering system, which is the principal ECF buffer, uses H2CO3 as its weak acid and bicarbonate salt such as sodium bicarbonate (NaHCO3) as its weak base.
It substitutes the weak H2CO3 for a strong acid such as hydrochloric acid or the weak bicarbonate base for a strong base such as sodium hydroxide. The bicarbonate buffering
system is a particularly efficient system because its components can be readily added or removed from the body. Hydrogen and potassium exchange freely across the cell membrane to regulate acid–base balance. Sodium is not part of the buffering system. Intracellular protein is part of the body protein buffer system; albumin is extracellular.
21.Arterial blood gases of a client with a diagnosis of acute renal failure reveal a pH of 7.25,
level of 21 mEq/L, and decreased PCO2 level accompanied by a respiratory rate of
32 . This client is most likely experiencing which disorder of acid–base balance? A) Metabolic acidosis
B) Metabolic alkalosis
C) Respiratory acidosis D) Respiratory alkalosis Ans: A
concentration along with a
decrease in pH. In metabolic acidosis, the body compensates for the decrease in pH by increasing the respiratory rate in an effort to decrease PCO2 and H2CO3 levels.
22.A client is brought to the emergency department semicomatose and a blood glucose reading of 673. He is diagnosed with diabetic ketoacidosis (DKA). Blood gas results are as
follows: serum pH 7.29 and HCO3
level 19 mEq/dL; PCO2 level 32 mm Hg. The nurse
should anticipate that which of the following orders may correct this diabetic ketosis? A) Administration of potassium chloride
B) Initiating an insulin IV infusion along with fluid replacement
C) Administering supplemental oxygen and rebreathing from a paper bag
D) Instituting a cough and deep breathing schedule for every hour while awake to improve ventilation
The treatment of metabolic acidosis focuses on correcting the condition that is causing
the disorder and restoring the fluids and electrolytes that have been lost from the body. For example, insulin administration and fluid replacement are frequently sufficient to correct a low pH in persons with diabetic ketosis. Administration of potassium chloride
is used as a treatment of metabolic alkalosis. Administering supplemental oxygen and
rebreathing from a paper bag are usual treatment of respiratory alkalosis. Instituting a cough and deep breathing schedule for every hour while awake to improve ventilation is usual treatment of respiratory acidosis.
23.A 77-year-old woman has been brought to the emergency department by her daughter because of a sudden and unprecedented onset of confusion. The client admits to ingesting large amounts of baking soda this morning to treat some “indigestion.” How will the woman's body attempt to resolve this disruption in acid–base balance?
A) Increase the depth of inspiration
B) Increasing renal H+ excretion
C) Increased renal HCO3
When neurologic manifestations occur with metabolic alkalosis, they include mental
confusion, hyperactive reflexes, tetany, and carpopedal spasm. Respiratory compensation will take place in an effort to counteract the client's metabolic alkalosis. This will involve hypoventilation. In addition, her kidneys are likely to decrease H+
excretion and HCO3
24.A client has received too much morphine (narcotic) in the postsurgical recovery room.
Blood gas results reveal the patient has developed respiratory acidosis. Which of the following assessment findings correlate with acute primary respiratory acidosis? Select all that apply.
B) Tingling/numbness in the fingers and toes
C) Muscle twitching
D) Respiratory depression E) Cardiac palpitations Ans: A, C, D
The signs and symptoms of respiratory acidosis depend on the rapidity of onset and
whether the condition is acute or chronic. Elevated levels of CO2 produce vasodilation of cerebral blood vessels, causing headache, blurred vision, irritability, muscle twitching,
and psychological disturbances. If severe and prolonged, it can cause an increase in CSF pressure and papilledema. Impaired consciousness, ranging from lethargy to coma, develops as the PCO2 rises to extreme levels. Paralysis of extremities may occur, and there may be respiratory depression. Respiratory alkalosis is associated with lightheadedness, dizziness, tingling, and numbness of the fingers and toes. These manifestations may be accompanied by sweating, palpitations, panic, air hunger, and dyspnea.
25.A very ill client has been admitted to the hospital for testing for possible septic shock.
The client reports light-headedness, dizziness, and tingling/numbness of the fingers and
toes. The nurse understands that this is likely due to which physiological phenomenon? A) Decrease in cerebral blood flow
B) Impaired alveolar ventilation
C) Gain in bicarbonate
D) Inability of the kidney to excrete the body's fixed acids
The sign/symptoms of respiratory alkalosis are associated with hyperexcitability of the nervous system and a decrease in cerebral blood flow. A decrease in the CO2 content of
the blood causes constriction of cerebral blood vessels. CO2 crosses the blood–brain barrier rather quickly; the manifestations of acute respiratory alkalosis are usually of sudden onset. The person often experiences light-headedness, dizziness, tingling, and numbness of the fingers and toes. Impaired alveolar ventilation is associated with respiratory acidosis. A gain in bicarbonate is associated with metabolic alkalosis. Inability of the kidney to excrete the body's fixed acids occurs with metabolic acidosis.
Concept 9: Acid-Base Balance
1. The patient had diarrhea for 5 days and developed an acid-base imbalance. Which statement would indicate that the nurse's teaching about the acid-base imbalance has been effective?
a. "To prevent another problem, I should eat less sodium during diarrhea."
b. "My blood became too acid because I lost some base in the diarrhea fluid."
c. "Diarrhea removes fluid from the body, so I should drink more ice water."
d. "I should try to slow my breathing so my acids and bases will be balanced."
Diarrhea causes metabolic acidosis through loss of bicarbonate, which is a base. Eating less sodium during diarrhea increases the risk of ECV deficit. Although diarrhea does remove fluid from the body, it also removes sodium and bicarbonate which need to be replaced. Rapid deep respirations are the compensatory mechanism for metabolic acidosis and should be encouraged rather than stopped.
REF: 73 OBJ: NCLEX® Client Needs Category: Physiological Integrity
2. The patient has type B chronic obstructive pulmonary disease (COPD) exacerbated by an acute upper respiratory infection. Which blood gas values should the nurse expect to see? a. pH high, PaCO2 high, HCO3- high
b. pH low, PaCO2 low, HCO3- low
c. pH low, PaCO2 high, HCO3- high
d. pH low, PaCO2 high, HCO3- normal
Type B COPD is a chronic disease that causes impaired excretion of carbonic acid, thus causing respiratory acidosis, with PaCO2 high and pH low. This chronic disease exists long enough for some renal compensation to occur, manifested by high HCO3-. Answers that include low or normal bicarbonate are not correct, because the renal compensation for respiratory acidosis involves excretion of more hydrogen ions than usual, with retention of bicarbonate in the blood. High pH occurs with alkalosis, not acidosis.
REF: 74 OBJ: NCLEX® Client Needs Category: Physiological Integrity
3. The patient has severe hyperthyroidism and will have surgery tomorrow. What assessment is most important for the nurse to assess in order to detect development of the acid-base imbalance for which the patient has highest risk?
a. Urine output and color
b. Level of consciousness
c. Heart rate and blood pressure
d. Lung sounds in lung bases
Thyroid hormone increases metabolic rate, causing a patient with severe hyperthyroidism to have high risk of metabolic acidosis from increased production of metabolic acids. Metabolic acidosis decreases level of consciousness. Changes in urine output, urine color, and lung sounds are not signs of metabolic acidosis. Although metabolic acidosis often causes tachycardia, many other factors influence heart rate and blood pressure, including thyroid hormone.
REF: 77-78|81 OBJ: NCLEX® Client Needs Category: Physiological Integrity
4. The nurse is making a home visit to a child who has a chronic disease. Which finding has the greatest implication for acid-base aspects of this patient's care?
a. Urine output is very small today.
b. Whites of the eyes appear more yellow.
c. Skin around the mouth is very chapped.
d. Skin is sweaty under three blankets.
Oliguria decreases the excretion of metabolic acids and is a risk factor for metabolic acidosis. Jaundice requires follow-up but is not an acid-base problem. Perioral chapped skin needs intervention but is not an acid-base issue. With three blankets, diaphoresis is not unusual.
REF: 74 OBJ: NCLEX® Client Needs Category: Physiological Integrity
5. The nurse has telephone messages from four patients who requested information and assistance. Which one should the nurse refer to a social worker or community agency first? a. "Is there a place that I can dispose of my unused morphine pills?"
b. "I want to lose at least 20 pounds without getting sick this time."
c. "I think I have asthma because I cough when dogs are near."
d. "I ran out of money and am cutting my insulin dose in half."
Decreasing an insulin dose by half creates high risk of diabetic ketoacidosis, and this patient has the highest priority. The other patients have less priority due to lower risk situations with longer time course before development of an acid-base imbalance. The coughing when dogs are near is not a sign of a severe asthma episode that causes respiratory acidosis, although this patient does need attention after the insulin situation is handled. Disposing of morphine properly helps prevent respiratory acidosis from opioid overdose. Guidance regarding weight loss helps prevent starvation ketoacidosis.
REF: 73 OBJ: NCLEX® Client Needs Category: Physiological Integrity
1. The patient is hyperventilating from anxiety and abdominal pain. Which assessment findings should the nurse attribute to respiratory alkalosis? (Select all that apply.)
a. Skin pale and cold
b. Tingling of fingertips
c. Heart rate of 102
d. Numbness around mouth
e. Cramping in feet