Chapter 39: Fluid, Electrolyte, and Acid-Base Balance

Normal levels of Sodium

136-145 mEq/L

Life threatening, fatal dehydration

15% loss in total body weight

Whole blood for infusion:

- used for situations with major blood loss (>25% circulating volume) -contraindicated for patients with history of heart failure or renal impairment

Packed RBCs for infusion:

-For patients with anemia or hemorrhage, can correct blood losses during and after surgery

Fresh frozen plasma for infusion:

-Used to treat hemorrhage as a volume expander and correct clotting disorders

Platelets for infusion:

-used for patients with thrombocytopenia or platelet dysfunction, and in patients who have had multiple transfusions of packed RBCs

Albumin for infusion:

-used to treat acute renal failure, burns, or trauma -can lead to fluid overload and heart failure/pulmonary edema

Autologous blood for infusion:

-uses the patient's own blood. Can be donated before surgery or infused during/after surgery -contraindicated in patients with history fo cancer or current infections

Mild dehydration

2% loss of total body weight

Normal levels of Potassium

3.5-5 mEq/L

Total body water (TBW) in elderly or an obese person

45%

Moderate dehydration

5% loss of total body weight

Normal pH of blood and body tissues:

7.35-7.45

Total body water (TBW) in infants

75%

Severe dehydration

8% loss in total body weight

Normal levels of Calcium

9-10.5 mg/dL

Hypomagnesemia

<1.3 mEq/L decreased absorption nasogastric suction draining fistulas prolonged diarrhea laxative abuse malabsorption syndrome ulcerative colitis Crohn disease increased renal excretion diuresis loop and thiazide diuretics

Hyponatremia

<136mEq/L Hypovolemic hyponatermia diuretics GI fluid loss (vomiting, diarrhea) Profuse diaphoresis Water intoxication Prolonged use of hypotonic IV solutions SIADH

Hypophosphatemia

<3 mg/dL hyperventilation respiratory alkalosis hyperglycemia absorption from GI tract starvation inadequate vitamin D chronic diarrhea, laxative abuse increased excretion by kidneys thiazide and loop diuretic diabetic ketoacidosis hyperparathyroidism hypocalcemia

Hypokalemia

<3.5 mEq/L Vomiting, gastric suction, diarrhea laxative abuse, frequent enemas use of potassium-wasting diuretics inadequate intake seen in anorexia, alcoholism, debilitated patients hyperaldosteronism

Hypocalcemia

<9 mg/DL Hypoparathyroidism Pancreatitis Vitamin D deficiency Inadequate intake of calcium rich foods Hyperphosphatemia Chronic alcoholism

Hypochloremia

<98 mEq/L overhydration heart failure SIADH vomiting or gastric suction Addison's disease Burns Metabolic alkalosis Medications such as aldosterone, bicarbonates, steroids, loop and thiazide diuretics

Hypercalcemia

>10.5 mg/dL prolonged bed rest hyperparathyroidism bone malignancy Paget disease Osteoporosis

Hyperchloremia

>106 mEq/L dehydration anemia excessive normal saline infusion Cushing syndrome Kidney disease Metabolic acidosis Respiratory alkalosis/hyperventilation

Hypernatremia

>145 mEq/L Excessive sodium intake Hypertonic IV solutions Hypertonic enteral feedings without adequate water Excessive loss of water due to Diarrhea, inadequate intake of water, insensible loss due to fever

Hypermagnesemia

>2.1 mEq/L Excessive intake of magnesium-containing antacids or cathartics prolonged us of intravenous magnesium sulfate Renal failure severe dehydration Adrenal insufficiency Leukemia

hyperphosphatemia

>4.5 mg/dL impaired renal function hypoparathyroidism acid-base imbalances cellular injury

Hyperkalemia

>5.0 mEq/L Renal failure Massive trauma, crushing injuries and burns Hemolysis IV potassium Potassium-sparing diuretics Acidosis (esp diabetic ketoacidosis)

Edema

Abnormal accumulation of fluid in the interstitial spaces

A patient has chronic diarrhea and repeated bouts of vomiting. A nurse is reviewing the patient's laboratory report. Which finding might be included in the laboratory study report? a. Serum K+ levels are more than 5 mEq/L. b. Total serum Ca2+ is greater than 10.5 mg/dL. c. Serum K+ levels are less than 3.5 mEq/L. d. Serum Mg2+ levels are greater than 2.5 mEq/L.

c. Serum K+ levels are less than 3.5 mEq/L. Chronic diarrhea and vomiting can cause imbalances in the body. Diarrhea and vomiting can result in the loss of electrolytes from the body, resulting in decreased potassium levels. Potassium, magnesium, and calcium levels may increase in the case of increased intake and absorption of these electrolytes.

Foods rich in sodium

Breads, cereals, chips, cheese, processed meats, hot dogs, bacon, ham, canned foods and table salt

Hypoxemia

Decreased oxygen concentration of arterial blood

Foods rich in potassium

Fish, whole grains, nuts, broccoli, cabbage, carrots, celery, cucumbers, potatoes with skin, spinach, tomatoes, apricots, bananas, cantaloupe, nectarines, oranges, tangerines

Hypervolemia

Fluid overload

Respiratory acidosis

Hypoventilation due to chest injury, asthma attack, pulmonary edema, brainstem injury, and medications (anesthetics, opioids and sedatives) -pH < 7.35 and PaCO2 > 45 mm Hg.

Hyperglycemia

Increased blood glucose level

Respiratory alkalosis

Pain, hyperventilation, salicylate overdose, nicotine overdose, increased metabolic states -pH >7.45 and PaCO2 <35 mm Hg

Hypertonic

Pulls water from the cell to the extracellular fluid compartment, leading to cell shrinkage

Metabolic acidosis

Shock, trauma, cardiac arrest, diabetic ketoacidosis, chronic renal failure, salicylate overdose, sepsis, chronic diarrhea -pH < 7.35, PaCO2 normal, HCO3 <21 mEq/L

Upon assessment, the nurse finds that a patient is positive for Chvostek sign and Trousseau sign and has tetany. Which electrolyte disturbance is responsible for this clinical presentation? a. Hypokalemia b. Hyponatremia c. Hypocalcemia d. Hypermagnesemia

c. Hypocalcemia Positive Chvostek sign, positive Trousseau sign, and presence of tetany indicate hypocalcemia. Low levels of calcium may affect the excitability of the nerve and muscle cells, causing cramps and abnormal muscle movements. Hypokalemia presents with muscular weakness and cardiac rhythm disturbances. Hyponatremia usually presents with nausea, vomiting, confusion, and seizures. Hypermagnesemia is an abnormally high magnesium concentration in the blood. Chvostek sign and Trousseau sign are associated with hypomagnesemia.

The nurse anticipates finding which of the following clinical manifestations for the patient who is dehydrated? Select all that apply. a. dry skin b. oliguria c. weight gain d. hypertension e. bounding pulses f. urine specific gravity > 1.030

a, b and f

The nurse is observing the patient who is receiving blood/blood products. In the first 15 minutes, the nurse stops transfusion of an acute hemolytic reaction, which is characterized by which of the following? Select all that apply. a. chills b. dyspnea c. fever d. itching e. lumbar pain f. vomiting

a, b, c, d, and e

For the patient with a central venous catheter, identify the correct actions. Select all that apply. a. A signed consent is required before insertion b. cleansing the site with soap and water before insertion is recommended c. gauze dressings are changed every 48 hours d. the central venous catheter is sutured to the vein used e. needle-free connectors are used f. have the patient wear a mask and/or turn the head away for dressing changes

a, c, e, and f

The nurse is caring for a patient diagnosed with chronic heart failure and understands that the patient is at risk of developing extracellular fluid volume excess. Which clinical findings would the nurse observe in this patient? Select all that apply. a. Ankle edema b. Postural hypotension c. Overnight weight loss d. Overnight weight gain e. Neck veins full when upright

a, d, e Chronic heart failure can cause extracellular fluid volume excess due to decreased renal output caused by elevated aldosterone. It can result in fluid retention manifested as ankle edema and weight gain. The neck veins may feel full on palpation when the patient is in upright position. Postural hypotension occurs when there is extracellular fluid volume deficit and not with excess of extracellular fluid volume. Weight loss is observed when there is extracellular fluid volume deficit and not with excess extracellular fluid volume.

Which dietary instructions does the nurse give to a patient with a calcium level of 8.0 mg/dL? a. "Include dairy products in your diet." b. "Do not regularly consume potatoes." c. "Include cured meats in your diet." d. "Avoid eating green leafy vegetables."

a. "Include dairy products in your diet." A level of 8.0 mg/dL indicates the patient has hypocalcemia, so the nurse instructs the patient to include calcium-rich foods such as dairy products in the diet. Potatoes are a rich source of potassium and should be avoided in case of hyperkalemia, not hypocalcemia. Cured meat is a rich source of sodium and thus should be included in the diet of a patient who has hyponatremia. Green leafy vegetables are rich in magnesium content and should be included in the diets of patients with hypomagnesemia.

As the nurse is assessing the caseload of patients for the day, which patient would she expect to be at the highest risk of developing dehydration? a. A 78-year-old patient with dementia b. A 47-year-old patient with hyperthyroidism c. A 53-year-old patient with pulmonary embolism d. A 32-year-old patient with a respiratory infection

a. A 78-year-old patient with dementia Older patients are at risk for dehydration because of altered responses to illness related to age. As a person ages, the thirst sensation tends to decrease. Elderly people often drink less fluid than is desirable. In addition, persons with dementia might not recognize the urge to drink. Patients who are in their 30s, 40s, or 50s with hyperthyroidism, pulmonary embolism, and respiratory infection are not at great risk for dehydration.

While reviewing the diagnostic reports of a patient, the nurse finds that the sodium level is 148 mEq/L, the potassium level is 4.8 mEq/L, the calcium level is 6.5 mg/dL, and the magnesium level is 1.1 mEq/L. Which electrolyte imbalance does the nurse infer from these findings? a. Low calcium levels b. Low sodium levels c. High potassium levels d. High magnesium levels

a. Low calcium levels A calcium level of 6.5 mg/dL indicates that the patient has hypocalcemia; normal calcium levels range from 8.5 to 10.5 mg/dL. Normal sodium levels range from 135 to 145 mEq/L; a sodium level of 148 mEq/L indicates a high sodium level, or hypernatremia. Normal potassium levels range from 3.5 to 5.0 mEq/L; a potassium level of 4.8 mEq/L is normal. Normal magnesium levels range from 1.3 to 2.1 mEq/L; a magnesium level of 1.1 mEq/L indicates that the patient has low magnesium levels, or hypomagnesemia.

A patient is brought into the emergency department after having had severe diarrhea. Arterial blood gases are assessed and the nurse anticipates that this patient will demonstrate the following results: a. pH-7.3, PaCO2-38mmHg, HCO3-19mEq/L b. pH-7.5, PaCO2-34mmHg, HCO3-20mEq/L c. pH-7.35, PaCO2-35mmHg, HCO3-24mEq/L d. pH-7.52, PaCO2-48mmHg, HCO3-28mEq/L

a. pH-7.3, PaCO2-38mmHg, HCO3-19mEq/L

Ascites

abnormal collection of fluid within the peritoneal cavity

The nurse weighs the patient who is taking a diuretic and finds he has lost 5 pounds over the last few days. What is approximate fluid loss that the patient has experienced? a. 1.5 L b. 2.3 L c. 4.6 L d. 5 L

b. 2.3 L

The nurse assesses that a patient has tachycardia, increased body temperature, and decreased blood pressure. On further assessment, the nurse finds the patient's pulse rate to be weak on palpation. Which complication would the nurse expect to find in this patient based on these findings? a. Metabolic acidosis b. Fluid volume deficit c. Fluid volume excess d. Respiratory alkalosis

b. Fluid volume deficit Tachycardia, which is increased heart rate, is the first indication of a fluid volume deficit. To ensure adequate oxygenation of the tissues, the heart rate accelerates to maintain the normal cardiac output. Fluid volume deficit leads to a weak pulse on palpation, and it also reduces the blood pressure due to a decrease in the circulating volume of the blood. Metabolic acidosis occurs due to loss of bicarbonate ions and an increase in acids produced as byproducts of a metabolic process and causes Kussmaul respirations. Fluid volume excess increases blood pressure and body temperature and causes a strong bounding pulse. Respiratory alkalosis is not associated with the symptoms of increased heart rate, increased body temperature, and decreased blood pressure; it occurs due to hyperventilation and excess exhalation of carbon dioxide.

Which of the following should be recommended for a patient requiring potassium supplementation? a. bacon b. cheese c. broccoli d. oranges e. tomatoes f. wheat germ

c, d, and f

Which assessment findings are consistent with hypovolemia? a. A 1 lb (0.5 kg) weight loss in 1 week, pale yellow urine b. Engorged neck veins when upright, bradycardia c. Dry mucous membranes, thready pulse, tachycardia d. Bounding radial pulse, flat neck veins when supine

c. Dry mucous membranes, thready pulse, tachycardia Hypovolemia (isotonic fluid volume deficit) is characterized by dry mucous membranes, thready pulse, and tachycardia, among other indicators. Weight loss of 1 lb (0.5 kg) in 1 week with pale yellow urine could indicate fat loss instead of fluid loss. Hypovolemia causes dark yellow urine rather than pale yellow. Engorged neck veins when upright, bradycardia, bounding radial pulse, and flat neck veins when supine are not clinical manifestations of fluid volume deficit.

The nurse observes that a patient appears to be hallucinating. On assessment, the nurse determines that the patient is always thirsty, has an elevated body temperature, and has a low level of consciousness. Which condition does the nurse suspect in this patient? a. Hypokalemia b. Hypercalcemia c. Hypernatremia d. Hypophosphatemia

c. Hypernatremia Hypernatremia indicates increased sodium levels, which may alter brain functioning. This may manifest as hallucinations, thirst, and decreasing levels of consciousness. Elevated temperature is also a clinical manifestation of hypernatremia. Hypokalemia causes irregular pulse, anorexia, nausea, vomiting, and constipation. Hypercalcemia causes decreased muscle strength, pathologic fractures, and renal calculi. Hypophosphatemia presents with muscle weakness, decreased deep tendon reflexes, and bone pain.

While reviewing the laboratory reports of a patient with fluid volume deficit, the nurse notices that the patient has lost 8% of the total body weight (TBW). Which abnormality does the nurse interpret from this finding? a. Edema b. Hypervolemia c. Severe dehydration d. Moderate dehydration

c. Severe dehydration If the patient has lost 8% of his or her TBW, it indicates severe dehydration. Hypertonic loss of fluids indicates dehydration and causes severe consequences. The severity of dehydration is determined by the percentage of the patient's TBW. Edema is the abnormal accumulation of fluid in the interstitial spaces that occurs from fluid volume excess. Fluid overload with movement of the fluid into the vascular space leads to hypervolemia. If a patient has a loss of 5% of his or her TBW, it indicates moderate dehydration.

One of the first indications of a fluid volume deficit is: a. polyuria b. hypothermia c. tachycardia d. increased blood pressure

c. tachycardia

Foods rich in calcium

cheese, ice cream, milk, yogurt, rhubarb, spinach, tofu

Major anions

chloride, bicarbonate, phosphate

Which patient being cared for by the nurse is at the highest risk of developing respiratory acidosis? a. A patient with hypokalemia b. A patient with pulmonary fibrosis c. A patient with salicylate overdose d. A patient with chronic obstructive pulmonary disease (COPD)

d. A patient with chronic obstructive pulmonary disease (COPD) Chronic respiratory acidosis is most commonly caused by COPD. Hypokalemia, pulmonary fibrosis, and salicylate overdose do not predispose a patient to respiratory acidosis. Hypokalemia can lead to cardiac dysrhythmias. Pulmonary fibrosis can result in respiratory arrest, and salicylate overdose results in central nervous system changes.

The nurse is caring for an elderly patient on digitalis therapy. The test reports indicate that the patient's potassium level is 3.0 mEq/L. The nurse instructs the patient to eat foods rich in which mineral? a. Sodium b. Calcium c. Phosphate d. Potassium

d. Potassium Normal potassium levels are between 3.5 and 5.0 mEq/L; the results indicate hypokalemia. Therefore the nurse should instruct the patient to eat potassium-rich foods. The effects of digitalis may be enhanced by hypokalemia, which can lead to digitalis toxicity. A patient with hyponatremia should eat sodium-rich foods. A patient with hypocalcemia should eat calcium-rich foods. A patient with hypophosphatemia should eat foods rich in phosphorus.

Hemolytic reaction

destruction of RBCs when patient receives mismatched blood transfusion

Isotonic

increases intravascular volume but does not cause fluid shifts in or out of the cell

Major cations

sodium, potassium, calcium, magnesium, hydrogen

Metabolic alkalosis

vomiting, nasogastric suctioning, overuse of bicarbonate antacids, hypokalemia, loop and thiazide diuretics -pH > 7.45, PaCO2 normal and HCO3>28 mEq/L