Chapter 25 Fluid, Electrolyte, and Acid-Base Balance Copyright © 2014, 2009 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Learning Objectives Theory 1) Discuss the various functions water performs in the body. 2) List the major electrolytes and the function of each. 3) Describe three ways in which body fluids are continually being distributed among the fluid compartments. 4) Identify the signs and symptoms of the common fluid and electrolyte imbalances. Slide 2 Copyright © 2014, 2009 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Learning Objectives Clinical Practice 1) Assess an assigned patient for signs of fluid and electrolyte imbalance. 2) From patient laboratory results, identify electrolyte values that are abnormal. 3) Implement teaching for the patient with hypokalemia. 4) Develop a plan of care for a patient who has a fluid and electrolyte imbalance. Slide 3 Copyright © 2014, 2009 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Composition of Body Fluids  Water  The two largest constituents of the body are water and electrolytes  Water serves four functions: Is a vehicle for transporting substances to and from cells Aids in heat regulation Assists in H + balance in the body Is a medium for enzymatic action of digestion Slide 4 Copyright © 2014, 2009 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Water  More than half of the body’s weight is water  Amount varies with age, sex, and health status  Males: approximately 60 %  Females: approximately 50%  Infants and the elderly more easily affected by changes in fluid balance Slide 5 Copyright © 2014, 2009 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Water (cont’d)  Infants and the elderly become dehydrated more rapidly  Infants’ kidneys reabsorb less fluid  Elderly have less antidiuretic hormone and diminished thirst sensation  Water is critical to maintaining homeostasis Slide 6 Copyright © 2014, 2009 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Sources of Water and Avenues of Loss  Intake  Oral1500 mL  Food800 mL  Metabolism200 mL  Total2500 mL  Output  Urine1500 mL  Perspiration400 mL  Feces200 mL  Expired air400 mL  Total2500 mL Slide 7 Copyright © 2014, 2009 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Composition of Body Fluids  Electrolytes  Minerals or salts dissolved in body fluids  In solution, they break up into ions  Ions have electrical charges  Cations have positive charges  Anions have negative charges  Each cation must be balanced by an anion  The major source of electrolytes is diet Slide 8 Copyright © 2014, 2009 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Electrolytes  Sodium: water regulation and balance  Potassium: nerve impulse transmission, muscle contraction, plasma, acid-base balance  Calcium: muscle activity, blood coagulation  Magnesium: nerve impulse transmission, muscle contraction  Phosphate: ATP production  Chloride: hydrochloric acid production, acid-base balance  Bicarbonate: acid-base balance Slide 9 Copyright © 2014, 2009 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Major Electrolytes: Normal Range  ElectrolyteNormal Range  Sodium mEq/L  Potassium mEq/L  Calcium mg/dL  Magnesium mg/dL  Phosphate mg/dL  Chloride mEq/L  Bicarbonate22-26 mEq/L Slide 10 Copyright © 2014, 2009 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Non-Electrolytes  Amino acids (proteins), glucose, and fatty acids  Remain bound together when dissolved in body fluid Slide 11 Copyright © 2014, 2009 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Non-Electrolytes: Blood  Normal circulating blood volume is 4 to 6 L  Composed of:  Erythrocytes (red cells)  Leukocytes (white cells)  Platelets (thrombocytes)  Carried in plasma Slide 12 Copyright © 2014, 2009 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Non-Electrolytes: Blood (cont’d)  Plasma proteins and colloids contribute to plasma osmotic pressure, which keeps fluid in the vascular compartment  Anything that alters body fluid volume also alters plasma volume  Plasma volume can affect blood pressure  Plasma volume can affect circulation Slide 13 Copyright © 2014, 2009 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Distribution of Body Fluids  Body fluids are:  Intracellular (within the cell)  Extracellular (outside the cell) Intravascular Interstitial Transcellular Slide 14 Copyright © 2014, 2009 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Extracellular Fluid  Makes up approximately 1/3 of the total body water  Transports nutrients, oxygen, and waste products to and from cells  Is regulated by renal, metabolic, and neurologic factors  Is high in sodium content Slide 15 Copyright © 2014, 2009 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Intravascular Fluid  The fluid within the blood vessels  Consists of plasma and fluid within the blood cells  Contains large amounts of protein and electrolytes, which help maintain intravascular volume Slide 16 Copyright © 2014, 2009 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Transcellular Fluids  Aqueous humor (in the eyes)  Saliva  Cerebrospinal fluid  Pleural, peritoneal, synovial, and pericardial fluids  Gastrointestinal secretions  Fluid in the urinary tract  Lymphatic system fluids Slide 17 Copyright © 2014, 2009 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Movement of Fluids and Electrolytes  Water taken in by ingesting fluids and food and through metabolism  Thirst mechanism in the hypothalamus regulates thirst based on concentration of electrolytes and solutes in circulation  Kidney the main organ of water secretion, with some loss in feces, perspiration, and breathing. Water retention based on aldosterone levels, antidiuretic hormone (ADH) levels, and atrial natriuretic peptide levels. Slide 18 Copyright © 2014, 2009 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Fluid, Electrolyte, and Nutrient Transport Mechanisms  Diffusion—passive transport  Process by which substances move back and forth across the membrane until evenly distributed throughout the available space  Substances move from high to low concentration until concentration on both sides of the membrane is equal  Glucose, oxygen, carbon dioxide, water, and other small ions and molecules move by diffusion Slide 19 Copyright © 2014, 2009 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Figure 25-2A: Diffusion Slide 20 Copyright © 2014, 2009 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Fluid, Electrolyte, and Nutrient Transport Mechanisms  Osmosis—passive transport  Movement of pure solvent (liquid) across a membrane  Water moves from area of less solute concentration to area of greater concentration until the solutions in the compartments are of equal concentration  Takes place via a semipermeable membrane Slide 21 Copyright © 2014, 2009 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Figure 25-2B: Osmosis Slide 22 Copyright © 2014, 2009 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Fluid, Electrolyte, and Nutrient Transport Mechanisms  Filtration—passive transport  Movement of water and suspended substances outward through a semipermeable membrane  Hydrostatic pressure  Causes fluid to press outward on the vessel  The force promotes filtration, forcing movement of water and electrolytes through the capillary wall to the interstitial fluid Slide 23 Copyright © 2014, 2009 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Figure 25-2D: Filtration Slide 24 Copyright © 2014, 2009 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Fluid, Electrolyte, and Nutrient Transport Mechanisms  Active transport  Requires cellular energy  Can move molecules into cells regardless of their electrical charge or the concentrations already in the cell  The energy source for the process is adenosine triphosphate (ATP)  Can move amino acids, glucose, iron, hydrogen, sodium, potassium, and calcium through the cell membrane Slide 25 Copyright © 2014, 2009 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Figure 25-2C: Active transport Slide 26 Copyright © 2014, 2009 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Fluid Volume Deficit  At risk:  Patients unable to take in enough fluid Impaired swallowing, extreme weakness, disorientation or coma, or unavailability of water  Patients who lose excessive amounts of fluid Prolonged vomiting, diarrhea, hemorrhage, diaphoresis (sweating), or excessive wound drainage  Result is dehydration Slide 27 Copyright © 2014, 2009 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Dehydration  Dehydration  When too little water in the plasma, water drawn out of the cells by osmosis to equalize concentration, and the cells shrivel  Treated by fluid administration, either orally or intravenously Slide 28 Copyright © 2014, 2009 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Signs and Symptoms of Dehydration  Thirst  Weakness  Dizziness  Postural hypotension  Decreased urine production  Concentrated urine  Dry, cracked lips  Dry mucous membranes  Thick saliva  Dry, scaly skin  Poor tissue turgor  Flat neck veins  Increased pulse rate  Weak, thready pulse  Elevated temperature Slide 29 Copyright © 2014, 2009 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Figure 25-3: Testing for tissue turgor and signs of dehydration Slide 30 Copyright © 2014, 2009 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Fluid Volume Excess  Healthy people do not ordinarily drink too much water  When people become ill they may take in more water than they excrete  Receive intravenous fluid too quickly  Given tap-water enemas  Drink more fluids than they can eliminate Slide 31 Copyright © 2014, 2009 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Fluid Volume Excess (cont’d)  Signs of overhydration  Weight gain  Crackles in the lungs (wet lungs)  Slow bounding pulse  Elevated blood pressure  Possibly edema Slide 32 Copyright © 2014, 2009 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Figure 25-4: Example of pitting edema Slide 33 Copyright © 2014, 2009 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Electrolyte Imbalance: Sodium  Hyponatremia  Sodium deficit; can be from decreased sodium or increased water intake and retention  May be caused by excessive vomiting or diarrhea  Hypernatremia  Sodium excess; most commonly from water loss from fever or respiratory infection Slide 34 Copyright © 2014, 2009 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Electrolyte Imbalance: Potassium  Hypokalemia  Occurs with excess potassium or loss of body water; may be from poor diet, vomiting, diarrhea, excessive sweating, or diuretic therapy  Hyperkalemia  Occurs with burns, crush injuries, uncontrolled diabetes mellitus, and renal failure Slide 35 Copyright © 2014, 2009 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Electrolyte Imbalance: Calcium  Hypocalcemia  Occurs with nutritional deficiency of calcium or vitamin D or in bone disorders such as metastatic cancer of the bone  Hypercalcemia  Most cases related to hyperparathyroidism or malignancy such as multiple myeloma Slide 36 Copyright © 2014, 2009 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Electrolyte Imbalance: Calcium (cont’d)  Calcium imbalances  Hypocalcemia Calcium level drops below 8.4 mg/dL Can occur from nutritional deficiency of calcium or vitamin D Occurs in disorders in which there is a shift of calcium into the bone  Hypercalcemia Calcium level above 10.6 mg/dL Most cases are related to hyperparathyroidism or malignancy in which there is metastasis with bone resorption Slide 37 Copyright © 2014, 2009 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Electrolyte Imbalance: Magnesium  Hypomagnesemia  Results from malabsorption, malnutrition, renal tubular dysfunction, thiazide diuretic use, extensive gastric suction, or diarrhea  Hypermagnesemia  Occurs only in presence of renal failure Slide 38 Copyright © 2014, 2009 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Electrolyte Imbalances  Anion imbalances  Hypochloremia Chloride level below 96 mEq/L is associated with hyponatremia  Hyperchloremia Chloride level above 106 mEq/L Occurs along with hypernatremia and a form of metabolic acidosis Slide 39 Copyright © 2014, 2009 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Electrolyte Imbalances (cont’d)  Anion imbalances  Hypophosphatemia Occurs when the level of phosphate falls below 3.0 mg/dL May result from use of aluminum-containing antacids, from vitamin D deficiency, or from hyperparathyroidism  Hyperphosphatemia A phosphate level above 4.5 mg/dL Commonly occurs in renal failure Slide 40 Copyright © 2014, 2009 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Acid-Base Balance  Important in maintaining homeostasis  pH: measure of the degree of acidity or alkalinity  Normal serum pH is 7.35 to 7.45  Death may occur if pH is less than 6.8 or greater than 7.8  Balance between bicarbonate and carbonic acid  Carbonic acid retained or removed by respiratory system  Bicarbonate retained or removed by kidneys Slide 41 Copyright © 2014, 2009 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Acid-Base Balance (cont’d)  Bicarbonate  Normal range is 22 to 26 mEq/L  Acts as buffer to neutralize excess acids in the body and maintain bicarbonate-to-carbonic acid ratio at 20:1  Kidneys selectively reabsorb or excrete bicarbonate to regulate serum levels and help maintain acid-base balance Slide 42 Copyright © 2014, 2009 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Acid-Base Balance (cont’d)  Control mechanisms  Blood buffer system Consists of weak acids and weak bases  Lungs Carbon dioxide and water are expired from the lungs  Urinary system Enzymes promote the dissociation of carbonic acid to free hydrogen ions Slide 43 Copyright © 2014, 2009 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Acid-Base Balance: Respiratory Acidosis  Increased carbon dioxide levels from:  Airway obstruction  Pneumonia, asthma  Chest injuries  Opiate intake  Chronic obstructive lung disease Slide 44 Copyright © 2014, 2009 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Acid-Base Balance: Metabolic Acidosis  An excessive loss of bicarbonate ions or retention of hydrogen ions caused by:  Kidney disease  Diabetic ketoacidosis  Circulatory failure  Shock states Slide 45 Copyright © 2014, 2009 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Acid-Base Balance: Respiratory Alkalosis  Usually caused by:  Anxiety  High fever  Hyperventilation  Salicylate poisoning (ASA overdose)  Encephalitis Slide 46 Copyright © 2014, 2009 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Acid-Base Balance: Metabolic Alkalosis  Caused by:  Vomiting  Gastric suctioning  Excessive antacid consumption  Diuretic therapy  Potassium deficit Slide 47 Copyright © 2014, 2009 by Saunders, an imprint of Elsevier Inc. All rights reserved.