Chapter 10: Principles of Fluid and Electrolytes

At which serum sodium concentration might convulsions or coma occur?

130 mEq/L (130 mmol/L) Normal serum concentration level ranges from 135 to 145 mEq/L (135-145 mmol/L). When the level dips below 135 mEq/L (135 mmol/L), hyponatremia occurs. Manifestations of hyponatremia include mental confusion, muscular weakness, anorexia, restlessness, elevated body temperature, tachycardia, nausea, vomiting, and personality changes. Convulsions or coma can occur if the deficit is severe. Values of 140, 142, and 145 mEq/L (mmol/L) are within the normal range

A client who is semiconscious presents with restlessness and weakness. The nurse assesses a dry, swollen tongue; body temperature of 99.3 °F; and a urine specific gravity of 1.020. What is the most likely serum sodium value for this client?

165 mEq/L Explanation: The normal sodium level is 135- 145 mEq/L (135-145 mmol/L). In hypernatremia, the serum sodium level exceeds 145 mEq/L (145 mmol/L) and the serum osmolality exceeds 300 mOsm/kg (300 mmol/L). The urine specific gravity and urine osmolality are increased as the kidneys attempt to conserve water (provided the water loss is from a route other than the kidneys). Body temperature may increase mildly, but it returns to normal after the hypernatremia is corrected

Which of the following arterial blood gas results would be consistent with metabolic alkalosis?

Serum bicarbonate of 28 mEq/L

Which solution is hypotonic?

0.45% NaCl

kidneys

A well-hydrated person excretes 1 to 2 L urine per day. A general rule is 1 mL of urine per kilogram of body weight per hour (1 mL/kg/h) in all age groups . For example, a 70-kg adult will excrete 70 mL/h; over 24 hours this equals approximately 1680 mL of urine. kidneys filter approximately 180 L of plasma per day

ADH

ADH is stored in the posterior pituitary gland and released as needed to conserve water. ADH is secreted in reaction to dehydration or blood loss and acts at the nephrons. ADH is secreted by the pituitary gland in reaction to dehydration or blood loss and acts at the nephrons. At the collecting duct of the nephron, ADH causes increased reabsorption of water from the tubules into the bloodstream

adrenal functions

Aldosterone, a mineralocorticoid secreted by the adrenal cortex. Increased secretion of aldosterone causes sodium retention (and thus water retention) and potassium loss. Conversely, decreased secretion of aldosterone causes sodium and water loss and potassium retention. Cortisol, another adrenocortical hormone, when secreted in large quantities it can also produce sodium and fluid retention.

A client reports tingling in the fingers as well as feeling depressed. The nurse assesses positive Trousseau's and Chvostek's signs. Which decreased laboratory results does the nurse observe when the client's laboratory work has returned?

Calcium Calcium deficit is associated with the following symptoms: numbness and tingling of the fingers, toes, and circumoral region; positive Trousseau's sign and Chvostek's sign; seizures, carpopedal spasms, hyperactive deep tendon reflexes, irritability, bronchospasm, anxiety, impaired clotting time, decreased prothrombin, diarrhea, and hypotension. Electrocardiogram findings associated with hypocalcemia include prolonged QT interval and lengthened ST

The physician has prescribed 0.9% sodium chloride IV for a hospitalized client in metabolic alkalosis. Which nursing actions are required to manage this client? Select all that apply

Compare ABG findings with previous results. Maintain intake and output records. Document presenting signs and symptoms. Explanation: Metabolic alkalosis results in increased plasma pH because of accumulated base bicarbonate or decreased hydrogen ion concentrations. The result is retention of sodium bicarbonate and increased base bicarbonate. Nursing management includes documenting all presenting signs and symptoms to provide accurate baseline data, monitoring laboratory values, comparing ABG findings with previous results (if any), maintaining accurate intake and output records to monitor fluid status, and implementing prescribed medical therapy.

The nurse is caring for a client with a serum sodium concentration of 113 mEq/L (113 mmol/L). The nurse should monitor the client for the development of which condition?

Confusion Normal serum concentration ranges from 135 to 145 mEq/L (135-145 mmol/L). Hyponatremia exists when the serum concentration decreases below 135 mEq/L (135 mmol/L). When the serum sodium concentration decreases to <115 mEq/L (<115 mmol/L), signs of increasing intracranial pressure, such as lethargy, confusion, muscle twitching, focal weakness, hemiparesis, papilledema, seizures, and death, may occur. General manifestations of hyponatremia include poor skin turgor, dry mucosa, headache, decreased saliva production, orthostatic fall in blood pressure, nausea, vomiting, and abdominal cramping. Neurologic changes, including altered mental status, status epilepticus, and coma, are probably related to cellular swelling and cerebral edema associated with hyponatremia. Hallucinations are associated with increased serum sodium concentrations.

The nurse is caring for a client with a serum potassium concentration of 6.0 mEq/L (6.0 mmol/L) and a fluid volume excess. The client is ordered to receive oral sodium polystyrene sulfonate and furosemide. What other order should the nurse anticipate giving?

Discontinue the intravenous lactated Ringer solution The lactated Ringer intravenous (IV) fluid is contributing to both the fluid volume excess and the hyperkalemia. In addition to the volume of IV fluids contributing to the fluid volume excess, lactated Ringer solution contains more sodium than daily requirements, and excess sodium worsens fluid volume excess. Lactated Ringer solution also contains potassium, which would worsen the hyperkalemia

A nurse is caring for an adult client with numerous draining wounds from gunshots. The client's pulse rate has increased from 100 to 130 beats per minute over the last hour. The nurse should further assess the client for which of the following?

Extracellular fluid volume deficit Fluid volume deficit (FVD) occurs when the loss extracellular fluid (ECF) volume exceeds the intake of fluid. FVD results from loss of body fluids and occurs more rapidly when coupled with decreased fluid intake. A cause of this loss is hemorrhage.

HYPOTONIC SOLUTIONS

HYPOTONIC SOLUTIONS 0.45% NaCl (half-strength saline) Na+ 77 mEq/L Cl− 77 mEq/L (154 mOsm/L) Also available with varying concentrations of dextrose (the most common is a 5% concentration) •Provides Na+, Cl−, and free water •Free water is desirable to aid the kidneys in elimination of solute •Lacking in electrolytes other than Na+ and Cl− •When mixed with 5% dextrose, the solution becomes slightly hypertonic to plasma temporarily until dextrose is metabolized. It leaves a hypotonic solution after dextrose metabolism. Provides 170 cal/L •Used to treat hypertonic dehydration, Na+ and Cl− depletion, and gastric fluid loss •Not indicated for third-space fluid shifts or increased intracranial pressure •Administer cautiously, because hypotonic solution can cause fluid shifts from vascular system into cells, resulting in cardiovascular collapse and increased intracranial pressure

HYPERTONIC SOLUTION

Hypertonic Solutions 3% NaCl (hypertonic saline) Na+ 513 mEq/L Cl− 513 mEq/L (1026 mOsm/L) 5% NaCL (hypertonic solution) Na+ 855 mEq/L Cl− 855 mEq/L (1710 mOsm/L) IV Mannitol 5-25% (hypertonic solution) (1372 mOsm/L contained in 25% solution) •Used to increase ECF volume, decrease cellular swelling •Highly hypertonic solution used only in critical situations to treat hyponatremia •Must be given slowly and cautiously, because it can cause intravascular volume overload and pulmonary edema •Assists in removing intracellular fluid excess •Highly hypertonic solution used to treat symptomatic hyponatremia •Administer slowly and cautiously because it can cause intravascular volume overload and pulmonary edema •Supplies no calories

Isotonic Solutions

Isotonic Solutions 0.9% NaCl (isotonic, also called normal saline [NS]) Na+ 154 mEq/L Cl− 154 mEq/L (308 mOsm/L) Also available with varying concentrations of dextrose (a 5% dextrose concentration is commonly used) •An isotonic solution that expands the extracellular fluid (ECF) volume; used in hypovolemic states, resuscitative efforts, shock, diabetic ketoacidosis, metabolic alkalosis, hypercalcemia, mild Na+ deficit •Supplies an excess of Na+ and Cl−; can cause fluid volume excess and hyperchloremic acidosis if used in excessive volumes, particularly in patients with compromised renal function, heart failure, or edema •When mixed with 5% dextrose, the resulting solution becomes temporarily hypertonic in relation to plasma and, in addition to the previously described electrolytes, provides 170 cal/L. After dextrose is metabolized it leaves an isotonic solution. •Only solution that may be given with blood products •Tonicity similar to plasma Lactated Ringer's solution Na+ 130 mEq/L K+ 4 mEq/L Ca++ 3 mEq/L Cl− 109 mEq/L Lactate (metabolized to bicarbonate) 28 mEq/L (274 mOsm/L) Also available with varying concentrations of dextrose (the most common is 5% dextrose) •An isotonic solution that contains multiple electrolytes in roughly the same concentration as found in plasma (note that solution is lacking in Mg++); provides 9 cal/L •Used in the treatment of hypovolemia, burns, fluid lost as bile or diarrhea, and for acute blood loss replacement •Lactate is rapidly metabolized into HCO3− in the body. Lactated Ringer's solution should not be used in lactic acidosis because the ability to convert lactate into HCO3− is impaired in this disorder •Not to be given with a pH >7.5 because bicarbonate is formed as lactate breaks down, causing alkalosis •Should not be used in kidney injury because it contains potassium and can cause hyperkalemia •Tonicity similar to plasma 5% dextrose in water (D5W) No electrolytes 50 g of dextrose •An isotonic solution that supplies 170 cal/L and free water to aid in renal excretion of solutes •Used in treatment of hypernatremia, fluid loss, and dehydration •Should not be used in excessive volumes in the early postoperative period (when antidiuretic hormone secretion is increased due to stress reaction) •Should not be used solely in treatment of fluid volume deficit because it dilutes plasma electrolyte concentrations •Contraindicated in head injury because it may cause increased intracranial pressure •Should not be used for fluid resuscitation because it can cause hyperglycemia •Should be used with caution in patients with renal or cardiac disease because of risk of fluid overload •Electrolyte-free solutions may cause peripheral circulatory collapse, anuria in patients with sodium deficiency, and increased body fluid loss •Converts to hypotonic solution as dextrose is metabolized by body. Over time, D5W without NaCl can cause water intoxication (intracellular fluid volume excess [FVE]) because the solution is hypotonic •Fluid therapy for an extended period of time without electrolytes may result in hypokalemia

A client hospitalized for treatment of a pulmonary embolism develops respiratory alkalosis. Which clinical findings commonly accompany respiratory alkalosis?

Light-headedness or paresthesia

The nurse is caring for a client undergoing alcohol withdrawal. Which serum laboratory value should the nurse monitor most closely?

Magnesium Explanation: Chronic alcohol abuse is a major cause of symptomatic hypomagnesemia in the United States. The serum magnesium concentration should be measured at least every 2 or 3 days in clients undergoing alcohol withdrawal. The serum magnesium concentration may be normal at admission but may decrease as a result of metabolic changes, such as the intracellular shift of magnesium associated with intravenous glucose administration

Your client's lab values are sodium 166 mEq/L, potassium 5.0 mEq/L, chloride 115 mEq/L, and bicarbonate 35 mEq/L. What condition is this client likely to have, judging by anion gap?

Metabolic acidosis

The client's lab values are sodium 166 mEq/L, potassium 5.0 mEq/L, chloride 115 mEq/L, and bicarbonate 35 mEq/L. What condition is this client likely to have, judging by anion gap?

Metabolic acidosis The anion gap is the difference between sodium and potassium cations and the sum of chloride and bicarbonate anions. An anion gap that exceeds 16 mEq/L indicates metabolic acidosis. In this case, the anion gap is (166 + 5) − (115 + 35), yielding 21 mEq/L, which suggests metabolic acidosis. Anion gap is not used to check for respiratory alkalosis, metabolic alkalosis, or respiratory acidosis.

A priority nursing intervention for a client with hypervolemia involves which of the following?

Monitoring respiratory status for signs and symptoms of pulmonary complications

Homeostatic Organs

Organs involved in homeostasis include the kidneys, heart, lungs, pituitary gland, adrenal glands, and parathyroid glands

Which electrolyte is a major cation in body fluid?

Potassium

A client with a suspected overdose of an unknown drug is admitted to the emergency department. Arterial blood gas values indicate respiratory acidosis. What should the nurse do first?

Prepare to assist with ventilation

Serum osmolality

Serum osmolality primarily reflects the concentration of sodium, although blood urea nitrogen (BUN) and glucose also play a major role in determining serum osmolality. Urine osmolality is determined by urea, creatinine, and uric acid.

Sodium ECF

Sodium ions, which are positively charged, far outnumber the other cations in the ECF. Because sodium concentration affects the overall concentration of the ECF, sodium is important in regulating the volume of body fluid.

A client seeks medical attention for an acute onset of severe thirst, polyuria, muscle weakness, nausea, and bone pain. Which health history information will the nurse report to the health care provider?

Takes high doses of vitamin D

ICF is potassium.

The ECF has a low concentration of potassium, and patients can tolerate only small changes in potassium concentration. Changes in potassium within the ECF can cause cardiac rhythm disturbances and hyperkalemia can cause cardiac arrest. Therefore, the release of large stores of intracellular potassium, typically caused by trauma to the cells and tissues, can be extremely dangerous.

baroreceptors

The baroreceptors are located in the left atrium and the carotid and aortic arches. These receptors respond to changes in the circulating blood volume and regulate sympathetic and parasympathetic neural activity as well as endocrine activities.

The nurse is caring for a client diagnosed with chronic obstructive pulmonary disease (COPD) and experiencing respiratory acidosis. The client asks what is making the acidotic state. The nurse is most correct to identify which result of the disease process that causes the fall in pH?

The lungs are not able to blow off carbon dioxide. Explanation: In clients with chronic respiratory acidosis, the client is unable to blow off carbon dioxide leaving in increased amount of hydrogen in the system. The increase in hydrogen ions leads to acidosis. In COPD, the client is able to breathe in oxygen and gas exchange can occur, it is the lungs ability to remove the carbon dioxide from the system. Although individuals with COPD frequently have a history of smoking, cilia is not the cause of the acidosis

Urine concentration

Urine concentration is monitored by measuring the urine specific gravity.

A nurse is reviewing a report of a client's routine urinalysis. Which value requires further investigation?

Urine pH of 3.0

Kidney homeostatic functions

Vital to the regulation of fluid and electrolyte balance, the kidneys normally filter 180 L of plasma every day in the adult and excrete 1 to 2 L of urine . They act both autonomously and in response to hormones, such as aldosterone and antidiuretic hormone (ADH) Major functions of the kidneys in maintaining normal fluid balance include the following: Regulation of ECF volume and osmolality by selective retention and excretion of body fluids Regulation of normal electrolyte levels in the ECF by selective electrolyte retention and excretion of hydrogen ions Regulation of pH of the ECF by retention and excretion of hydrogen ions Excretion of metabolic wastes and toxic substances Given these functions, failure of the kidneys results in multiple fluid and electrolyte abnormalities.

renin-angiotensin-aldosterone system

When the kidneys sense low perfusion or diminished blood pressure, they secrete renin , which triggers the renin-angiotensin-aldosterone system. This system is one of the body's most important compensatory mechanisms in maintaining fluid balance. 1. Renin circulates to the liver and converts angiotensinogen, a protein synthesized by the liver, into angiotensin I. 2. Angiotensin-converting enzyme (ACE) converts angiotensin I to angiotensin II. 3. Angiotensin II stimulates potent peripheral arterial vasoconstriction which increases arterial blood pressure. 4.Angiotensin II also stimulates the adrenal gland to secrete aldosterone. 5. Aldosterone increases sodium and water reabsorption at the nephron into the bloodstream. This raises blood volume and blood pressure. Aldosterone also stimulates secretion of potassium into the nephron tubules, which in turn causes potassium excretion by the kidney

A nurse is providing client teaching about the body's plasma pH and the client asks the nurse what is the major chemical regulator of plasma pH. What is the best response by the nurse?

bicarbonate-carbonic acid buffer system The major chemical regulator of plasma pH is the bicarbonate-carbonic acid buffer system. The renin-angiotensin-aldosterone system regulates blood pressure. The sodium-potassium pump regulate homeostasis. The ADH-ANP buffer system regulates water balance in the body.

Creatinine

breakdown product of muscle metabolism that is almost totally cleared from the bloodstream and excreted by the kidney. It is a better indicator of renal function than BUN because it does not vary with protein intake or hydration status

Isotonic solutions

composed of 0.9% NaCl; the same sodium and chloride concentration as the bloodstream and the same water concentration as the bloodstream. Isotonic solutions do not provoke water movement between ICF or ECF compartments. Isotonic solutions expand the plasma volume of the blood

Hypertonic solutions

composed of greater concentration of NaCl compared to blood (e.g., 3% NaCl). Hypertonic solutions contain more solute concentration and less water than the bloodstream. IV hypertonic solution can be infused into the bloodstream to pull water from the ICF into the ECF. The movement of water from ICF to ECF will cause dehydration of the cells. Useful in disorders of severe edema; particularly cerebral edema, which requires immediate treatment. Sodium, glucose, and mannitol are examples of solutes capable of affecting water movement from ICF to ECF. Mannitol, a nonresorbable sugar alcohol, in water is an IV solution that can be used to move water from ICF to ECF rapidly. IV mannitol can induce a condition termed osmotic diuresis; it is most commonly used to decrease cerebral edema

Hypotonic solutions

composed of less sodium chloride concentration compared to the blood; for example, 0.45% NaCl or 0.225% NaCl. Hypotonic solutions contain less solute but more water than the bloodstream. IV hypotonic solution infusions can be used to move water from the ECF into the ICF. IV hypotonic solutions can be used to hydrate a patient as they contain high water concentration

parathyroid functions

embedded in the thyroid gland, regulate calcium and phosphate balance by means of parathyroid hormone (PTH). PTH influences reabsorption of calcium from the bones into the bloodstream, calcium absorption from the intestine, and calcium reabsorption into the bloodstream from the renal tubules

A client with severe hypervolemia is prescribed a loop diuretic and the nurse is concerned with the client experiencing significant sodium and potassium losses. What drug was most likely prescribed?

furosemide

A nurse is assessing a client's reflexes. Which condition does the nurse need to confirm when tapping the facial nerve of a client who has dysphagia?

hypomagnesemia

Clients diagnosed with hypervolemia should avoid sweet or dry food because it:

increases the client's desire to consume fluid.

BUN

laboratory value that measures the amount of urea in the bloodstream. The normal range of BUN is 10 to 20 mg/dL (3.6 to 7.2 mmol/L). BUN level can vary with renal function, amount of cellular breakdown, protein intake, and hydration status. If urine output decreases, as occurs in renal dysfunction, then urea is not excreted and accumulates in the bloodstream causing an increase. Increased BUN can also occur if water content in the bloodstream decreases due to dehydration. a high protein diet, there is an increased amino acid content in the bloodstream, which increases nitrogen content of the blood, increasing BUN Factors that decrease BUN include end-stage liver disease, a low protein diet, starvation (due to low protein), and any condition that results in expanded fluid volume which dilutes urea in the blood

specific gravity

measures the density of urine compared to water. The specific gravity of urine is compared to that of distilled water, which has a specific gravity of 1.000. The normal range of urine specific gravity is 1.005 to 1.030urine with a specific gravity of 1.030 is very concentrated or low in water content.

Hematocrit

measures the percentage of red blood cells (RBCs) (erythrocytes) of whole blood and normally ranges from 42% to 52% in men and 35% to 47% in women. Conditions that increase the hematocrit value are dehydration and polycythemia. Dehydration causes decreased water content of the blood which concentrates the RBCs in the bloodstream. Polycythemia is a disorder in which there is an abnormally high number of RBCs made by the bone marrow, which in turn increases the number of RBCs in the bloodstream.

When evaluating arterial blood gases (ABGs), which value is consistent with metabolic alkalosis

pH 7.48 Explanation: Metabolic alkalosis is a clinical disturbance characterized by a high pH and high plasma bicarbonate concentration. The HCO value is below normal. The PaCO value and the oxygen saturation level are within a normal range.

A client with Guillain-Barré syndrome develops respiratory acidosis as a result of reduced alveolar ventilation. Which combination of arterial blood gas (ABG) values confirms respiratory acidosis?

pH, 7.25; PaCO2 50 mm Hg

A client with respiratory acidosis is admitted to the intensive care unit for close observation. What client complication associated with respiratory acidosis would the nurse observe?

papilledema If respiratory acidosis is severe, intracranial pressure may rise, causing papilledema. Stroke and hyperglycemia are not associated with respiratory acidosis. Seizures may complicate respiratory alkalosis, not respiratory acidosis

Tonicity

the ability of solutes to cause an osmotic driving force that promotes water movement from one compartment to another. Movement of water is either from ICF to ECF or ECF to ICF Tonicity most commonly refers to the NaCl content of the solution.

osmolarity:

the concentration of solutes or dissolved particles