Fluids, Electrolytes, and Acid-Base, Spring 2023, PDF

Chapter 32 Fluids, Electrolytes, and Acid–Base Copyright Copyright © 2021 © Wolters 2021 Wolters Kluwer Health Kluwer| Lippincott...

Chapter 32 Fluids, Electrolytes, and Acid–Base Copyright Copyright © 2021 © Wolters 2021 Wolters Kluwer Health Kluwer| Lippincott All RightsWilliams Reserved & Wilkins Fluid Compartments #1 ❖ Body fluid is water containing electrolytes, blood cells, and other soluble molecules. ❖ Fluid contained within compartments (spaces): ▪ Intracellular fluid (ICF) ▪ Extracellular fluid (ECF) (intravascular and interstitial fluid) ❖ Body monitors and controls: ▪ Volume of fluid in the extracellular space ▪ Osmolality of body fluids Copyright © 2021 Wolters Kluwer All Rights Reserved Body Fluid Compartments ❖ Intracellular fluid: Fluid located within the cells o Active transport ❖ Extracellular fluid: All fluid outside of the cells o Intravascular fluid: Fluid inside the blood and lymphatic vessels; vascular volume is the most regulated aspect of fluid balance (BP maintenance) o Interstitial fluid: Fluid between the cells; water balance controlled through active electrolyte transport Copyright © 2021 Wolters Kluwer All Rights Reserved Fluid Compartments #2 Copyright © 2021 Wolters Kluwer All Rights Reserved Water Concentration (Osmolality) of Body Fluid ❖ Osmolality: The proportion of dissolved particles in a given weight of fluid (mOsm/kg). ❖ Osmolarity: The concentration of dissolved substances in a given volume of fluid (mOsm/L). o Normal serum osmolality range is from 280 to 300 mOsm/kg. o Hypothalamic cells monitor changes in body fluid osmolality and control secretion of ADH, which adjusts amount of water excreted in urine. Copyright © 2021 Wolters Kluwer All Rights Reserved Body Fluid Electrolytes ❖ Sodium (Na+): Most abundant cation in the ECF ❖ Potassium (K+): Commonly found in ICF; is essential for normal cardiac, neural, and muscle function and contractility ❖ Calcium (Ca++): Essential in blood clotting, glycolysis and teeth and bone structure; important in wound healing, synaptic transmission in nervous tissue, membrane excitability, and muscle contractility ❖ Magnesium (Mg++): Important in regulating neuromuscular function and cardiac activity ❖ Phosphorus (HPO4− and H2PO4−): Important in energy metabolism, structure of bones and membranes, and synthesis of nucleic acids Copyright © 2021 Wolters Kluwer All Rights Reserved Question #1 ❖ Which of the following is a biologic anion in the body? A. Sodium B. Phosphate C. Potassium D. Calcium Copyright © 2021 Wolters Kluwer All Rights Reserved Answer to Question #1 ❖ B. Phosphate ❖ Rationale: Phosphate (HPO4– and H2PO4–) is an anion. Positively charged ions are referred to as cations, and negatively charged ions are anions. Biologically important cations include sodium (Na+), potassium (K+), calcium (Ca++), and magnesium (Mg++). Copyright © 2021 Wolters Kluwer All Rights Reserved Processes of Fluid and Electrolyte Movement ❖ Diffusion: Movement of molecules from an area of higher molecular concentration to an area of lower concentration ❖ Osmosis: Movement of a fluid through a semipermeable membrane ❖ Active transport: Process requiring energy by which molecules are moved across membranes from an area of lesser concentration to an area of greater concentration ❖ Filtration: Transfer of water and dissolved substances through a permeable membrane from a region of high pressure to a region of low pressure. Copyright © 2021 Wolters Kluwer All Rights Reserved Pressures Affecting Fluid and Electrolyte Movement ❖ Osmotic pressure: The force of attraction for water by undissolved particles which keeps fluid within blood vessels and opposes net flow outward ❖ Hydrostatic pressure: Causes filtration of fluid from an area of higher pressure to an area of lower pressure ❖ Filtration pressure: Hydrostatic pressure minus osmotic pressure equals filtration pressure Copyright © 2021 Wolters Kluwer All Rights Reserved Question #2 ❖ Which of the following processes of fluid and electrolyte movement occurs in glomerular capillaries? A. Osmosis B. Diffusion C. Active transport D. Filtration Copyright © 2021 Wolters Kluwer All Rights Reserved Answer to Question #2 ❖ D. Filtration ❖ Rationale: Filtration involves the transfer of water and dissolved substances through a permeable membrane from a region of high pressure to a region of low pressure. Filtration occurs within the kidney’s glomerular capillaries and in blood capillaries. Copyright © 2021 Wolters Kluwer All Rights Reserved Balancing Fluid Volume ❖ In a healthy person, fluids intake and output are nearly equal primarily due to the kidneys and the hormones which direct the kidneys to retain or excrete more urine. ❖ When there is a decrease in extracellular volume, the thirst volume in the brain is stimulated so the person seeks out fluid and drinks. ❖ The body balances fluid volume through: o Thirst o Kidneys o Renin-angiotensin-aldosterone system o Atrial natriuretic peptide (ANP) Copyright © 2021 Wolters Kluwer All Rights Reserved Fluid Volume Deficit Hypovolemia is a fluid volume deficit which is a diminished blood volume. Causes may include: Fluid loss, Reduced fluid intake, Fluid shift out of vascular space Conditions that can result in hypovolemia are (not an extensive list): Fluid loss, Hemorrhage, Frequent urination, Vomiting, Diarrhea, Fistulas, Fever, Excessive nasogastric suctioning, Burns Patients with hypovolemia may present with: Hypotension, tachycardia, THREADY fast pulse, thirst, poor skin turgor, dry mucus membrane, decreased urinary output, flattened neck veins, if severe- even shock! MUST TREAT THE CAUSE!! Copyright © 2021 Wolters Kluwer All Rights Reserved Fluid Volume Excess Hypervolemia is a condition of fluid volume excess. When fluid excess is in the intravascular space it is called Hypervolemia. When fluid excess is in the interstitial space is called Edema. Can be local or Generalized. When fluid excess is in other body compartments it is called Third Spacing. May result in a body space or soft tissue. Clinical Signs of Hypervolemia include: Dyspnea, crackles, tachypnea, BOUNDING rapid pulse, Hypertension, distended neck veins, ventricular gallop, clammy skin. MUST TREAT REASON! Copyright © 2021 Wolters Kluwer All Rights Reserved Electrolytes ❖ Electrolytes are chemical compounds found in solutions which have a small electrolytical charge. Electrolytes are ions and can be positivity or negatively charged. o If positively charged they are called CATIONS. o If negatively charged they are called ANIONS. ❖ Regulated through several mechanisms to ensure regular concentrations including dietary intake and hormonal regulation, but the execration of sodium is primarily through the kidneys making it the major player. Copyright © 2021 Wolters Kluwer All Rights Reserved Sodium ❖ SODIUM is the major cation of ECF and it often combines with chloride. Remember, usually where water goes, sodium will follow. Sodium is largely responsible for the osmotic pressure of the ECF compartments. Thus influencing water distribution throughout the body. It also aids in Nerve and muscle fiber transmission as well as influencing the concentration of potassium and Chloride in the body. ❖ Normal serum sodium is 135-145 mEq/L. ❖ A deficit is called Hyponatremia. This causes water to shift out of the extracellular spaces and INTO the cells. May be caused by excessive sodium loss or excessive water intake that dilutes the solutes. ❖ An excess is called Hypernatremia. This causes water to shift OUT of the cells. May be caused by intake of excess sodium or loss of fluids. Copyright © 2021 Wolters Kluwer All Rights Reserved Potassium ❖ Potassium is the major cation within the body within body’s cells. It is the predominate intracellular ion. It is the major mineral in the fluids of all body cells. Important in creating the resting membrane potential in neuromuscular tissue function such as skeletal, cardiac, and smooth muscle. It plays an important role in the body’s use of glucose for energy. It is essential in converting amino acids to protein. Potassium levels are highly regulated by the kidneys and also through dietary intake. ❖ Normal range is 3.5-5.0 mEq/L ❖ Decrease: Hypokalemia. Some causes include: lcholism, alkalosis, Anorexia Nervosa, diuretic use, etc. Complications include: Apnea, hypotonic bowel sounds, muscle fatigue, EKG changes. ❖ Increase: Hyperkalemia. Some causes include acidosis, burns, crushing injuries, hypoaldosteronism, rapid IV administration, renal failure. Complications include: Abdominal pain, tingling fingers, EKG changes including cardiac arrest. MUST TREAT THE CAUSE! Copyright © 2021 Wolters Kluwer All Rights Reserved Calcium Calcium is an essential cation that is widely distributed throughout the body. It is essential for neuromuscular function, transmission of nerve impulses, contraction of skeletal and cardiac muscle, blood clotting, maintenance of normal cell membrane permeability, and formation of bones and teeth. Regulated through dietary intake, GI absorption requires vitamin D, PTH regulates absorption/excretion, calcitonin (produced and secreted by the thyroid gland) decreases serum calcium levels by opposing bone absorption, has an inverse relationship with phosphate. Normal serum range: 8.2-10.5 mEq/L Low levels are called: Hypocalcemia. Caused by hypoparathyroidism, hyperphosphatemia, malabsorption, vitamin D deficiency, excessive administration of citrated blood, and hypoalbuminemia. High Levels are called: Hypercalcemia. Caused by low phosphates in the blood, certain cancers, thyrotoxicosis, acromegaly, renal failure. Bonus: Trousseau’s sign & Chvostek’s sign can be seen on assessment with HYPOcalcemia Copyright © 2021 Wolters Kluwer All Rights Reserved Phosphorus Phosphorus is a major intracellular anion and plays an essential role in many body functions. It is an essential component of bones. Also affects metabolism of carbs, lipids, and protein. It is also a major buffer in maintain acid-base balance. Obtained through dietary intake and is excreted by the kidneys and PTH. Normal range is 2.5-4.5 mg/dL Decreased levels: Hypophosphatemia. Caused by alkalosis, DKA, Hyperalimentation, Hyperparathyroidism, phosphate-binding antacids containing aluminum and calcium. Increased levels: Hyperphosphatemia. Caused by Renal failure, hypoparathyroidism, chemotherapy, large intake of calcium, and excessive use of phosphate laxatives or enemas. Copyright © 2021 Wolters Kluwer All Rights Reserved Magnesium Magnesium is a major intracellular cation. Most of the body’s magnesium is stored in bone, soft tissue, and bone. Very little is found in the blood. Magnesium activates many enzymes. It plays a vital role in the electrical conduction of muscle, nerves and cardiac tissue as well as being important in carbohydrate and protein metabolism. It is essential in protein and DNA syntheses. Magnesium is obtained through out the diet. PTH regulates its absorption and excretion. It is influenced by calcium absorption. It is excreted by the kidneys. Normal range is 1.5-2.5 mg/dL Low levels: Hypomagnesemia. Caused by insufficient intake such as in malnutrition, chronic alcoholism, or prolonged NPO states. Also can be caused by inadequate absorption, fistulas, diarrhea, SIADH, small bowel bypass surgery, hypercalcemia. Elevated levels: Hypermagnesemia. Causes include decreased renal excretion, increased intake, traumatic soft tissue injury. Copyright © 2021 Wolters Kluwer All Rights Reserved Normal Acid–Base Balance ❖ Acids, bases, and pH ❖ Acids and bases in the blood ❖ Acid–base balance regulation o Buffering o Compensation ▪ Respiratory compensation ▪ Renal compensation Copyright © 2021 Wolters Kluwer All Rights Reserved Chloride Chloride is the major anion of the ECF. Plays an important role in maintaining the acid-base balance. Like sodium, it helps to maintain osmotic pressure in the intravascular system. It also helps to maintain the acidity of gastric secretions in the form of hydrochloric acid. The kidneys regulate chloride. Normal serum range is 95-105 mEq/L Decreases in Chloride are called Hypochloremia. Causes are due to a loss of hydrochloric acid from excessive vomiting and GI suctioning. Elevations in Chloride are called Hyperchloremia. Causes are due to an increase such as from excessive ingestion or decreased excretion from the kidney. Copyright © 2021 Wolters Kluwer All Rights Reserved pH Scale Copyright © 2021 Wolters Kluwer All Rights Reserved Question #3 ❖ Is the following statement true or false? ❖ A fluid with a pH of 5.3 would be considered an acidic substance. Copyright © 2021 Wolters Kluwer All Rights Reserved Answer to Question #3 ❖ True ❖ Rationale: A pH of 7.0 is considered neutral, with a value reading below that considered acidic and a value above that considered basic. Copyright © 2021 Wolters Kluwer All Rights Reserved Factors Affecting Fluid, Electrolyte, and Acid–Base Balance #1 ❖ Fluid and food intake ❖ Fluid and electrolyte output ❖ Vomiting ❖ Diarrhea ❖ Diaphoresis ❖ Use of diuretics ❖ Stress ❖ Chronic illness Copyright © 2021 Wolters Kluwer All Rights Reserved Fluid and food intake ❖ Average daily intake for adult: o 1300 ml of water o 1000 ml from food o 300 ml from food oxidation ❖ Thirst mechanism helps regulate fluid intake ❖ Psychological factors may stimulate thirst Copyright © 2021 Wolters Kluwer All Rights Reserved Fluid and electrolyte output ❖ From kidneys as urine (normal output 1500mL/day) ❖ From skin as perspiration (100-200 mL fluid/day) ❖ From skin as insensible fluid loss (300-400 mL/day) ❖ From GI tract as feces daily (200 mL/day) ❖ From lungs via respiration (300 mL/day) ❖ Nurse must assess carefully for s/sx of imbalance Copyright © 2021 Wolters Kluwer All Rights Reserved V/D & Diaphoresis ❖ Vomiting: o Increases risk of ECF volume deficit 7/or metabolic alkalosis & Hypokalemia o Causes decreased ability to maintain adequate intake ❖ Diarrhea: o Increases risk of ECF volume deficit &/or metabolic acidosis & hypokalemia o Oral rehydration fluids replace lost F&E ❖ Diaphoresis (Excessive sweating) o Can occasionally increase loss of F/E Copyright © 2021 Wolters Kluwer All Rights Reserved Use of diuretics & Stress ❖ Diuretics: o May remove too much ECF causing deficit o Promote excretion of potassium & Magnesium increasing the risk of electrolyte deficits (Except for potassium-sparing diuretics) ❖ Stress: o Causes increase in aldosterone which causes ECF retention. o AVP production increases resulting in renal excretion of water Copyright © 2021 Wolters Kluwer All Rights Reserved Chronic Illness ❖ Imbalances commonly accompany the following: o Renal Failure (filtering issues) o Cardiac Failure (pump failure leads to fluid retention) o Liver Failure (Ascites) o Respiratory Failures (various issues with carbon dioxide and pH) o Also seen with treatments such as chemotherapy for caner Copyright © 2021 Wolters Kluwer All Rights Reserved Factors Affecting Fluid, Electrolyte, and Acid–Base Balance #2 ❖ Renal failure ❖ Cardiac failure ❖ Liver failure ❖ Respiratory failure ❖ Surgery ❖ Pregnancy Copyright © 2021 Wolters Kluwer All Rights Reserved Altered Fluid, Electrolyte, and Acid–Base Balance: Fluid Imbalance ❖ Extracellular fluid volume imbalance o Extracellular fluid volume deficit o Extracellular fluid volume excess ❖ Water or osmolality imbalance o Water deficit or hyperosmolality o Water excess or hyposmolality Copyright © 2021 Wolters Kluwer All Rights Reserved Altered Fluid, Electrolyte, and Acid–Base Balance: Acid–Base Imbalances ❖ Respiratory acidosis ❖ Metabolic acidosis ❖ Respiratory alkalosis ❖ Metabolic alkalosis Copyright © 2021 Wolters Kluwer All Rights Reserved Manifestations of Fluid, Electrolyte, or Acid–Base Imbalances ❖ Imbalance of intake and output and body weight ❖ Changes in mental status ❖ Changes in vital signs o Respiratory rate and depth o Heart rate and rhythm o Postural pulse rate and blood pressure ❖ Abnormal tissue hydration ❖ Abnormal muscle tone or sensation Copyright © 2021 Wolters Kluwer All Rights Reserved Life Span Considerations in Fluid and Electrolyte Balance Age is a significant factor in fluid and electrolyte balance. The very young and the very old are at greatest risk generally Copyright © 2021 Wolters Kluwer All Rights Reserved Newborn and infant ❖ Proportionately larger % of total body water weight as compared to adults (70-80% as compared to 60%) THUS easier to dehydrate!! ❖ Greater amount of fluid contained within ECF than adults ❖ Immature Kidneys-Unable to concentrate urine fully ❖ Increased insensible fluid loss-Metabolic and respiratory rates higher naturally for this age group Copyright © 2021 Wolters Kluwer All Rights Reserved Toddler and preschooler ❖ Approx. 62% body weight is water ❖ Fluid requirements vary in this age group based on height and weight (average 1000-1200 mL over 24 hrs) ❖ Output increases by age o 500-700 mL/day @ 2y/o o 600-850 mL/day @ 5y/o ❖ Water loss via skin greater in this group as compared to adults Copyright © 2021 Wolters Kluwer All Rights Reserved Child and adolescent ❖ By 12 y/o ration of body water to weight approx. the same as that of an adult ❖ Dietary education important o Encourage water & other nutrients o Caution regarding excessive exercise without fluid replacement especially in hot weather o Balanced dietary intake important (Discourage fad diets or purging to loose weight-can cause F&E imbalances) Copyright © 2021 Wolters Kluwer All Rights Reserved Adult and older adult ❖ After 25y/o: #of kidney nephrons begins to decrease ❖ After 30y/o: 10% decrease per decade in kidney mass, blood flow, & glomerular filtration rate ❖ After 40y/o: amount of adipose tissue tends to increase which alters the % of body water ❖ This age group often has: chronic illnesses, takes diuretics, uses laxatives excessively, restricts fluids to decrease need for restroom breaks ❖ Often have tests/procedures that require bowel prep, etc. Copyright © 2021 Wolters Kluwer All Rights Reserved Cultural considerations ❖ Incidence & mortality of chronic kidney disease is higher in African Americans compared to Caucasians. (Research has seen up to 3X’s higher risk) ❖ It is thought that high rates of hypertension, diabetes, and obesity in this group may be contributing factors. Research has shown that people with hypertension, diabetes, and obesity tend to be more sensitive to sodium. Copyright © 2021 Wolters Kluwer All Rights Reserved Question #4 ❖ Infants who are losing fluid need to be monitored carefully. Nurses know that all of the following contribute to this fluid and electrolyte vulnerability except: A. Kidney immaturity B. The intracellular compartment contains the most bodily fluid C. Increased body surface area in relation to body size D. A proportionately larger percentage of total body weight as water Copyright © 2021 Wolters Kluwer All Rights Reserved Answer to Question #4 ❖ B. The intracellular compartment contains the most bodily fluid. ❖ Rationale: In the case of newborns and infants, a greater amount of the fluid is contained within the extracellular compartment when compared to adults, thus leading to a greater vulnerability related to fluid loss. Copyright © 2021 Wolters Kluwer All Rights Reserved Assessment: Normal Pattern ❖ History of fluid, electrolyte, or acid–base problems ❖ Dietary restrictions ❖ Recent increased thirst or a decrease in fluid intake ❖ Amount and pattern of urine output and recent changes Copyright © 2021 Wolters Kluwer All Rights Reserved Assessment: Risk and Dysfunction Identification ❖ Risk identification o Recent illnesses with nausea, vomiting, diarrhea, or severe diaphoresis o History of chronic diseases o Use of prescription or nonprescription medications o Religious practices, such as prolonged fasting ❖ Dysfunction identification Copyright © 2021 Wolters Kluwer All Rights Reserved Physical Assessment ❖ Intake and output ❖ Body weight ❖ Integumentary assessment ❖ Vital signs ❖ Neck veins ❖ Central venous pressure ❖ Bowel assessment Copyright © 2021 Wolters Kluwer All Rights Reserved Intake and output ❖ Intake o All oral & parenteral fluids. Count all foods that become liquid at room temperature ❖ Output o Urine, liquid stool, vomit, wound drainage, NG tube drainage, etc. ❖ Recording: o I&O may be ordered by provider, or the nurse pay decide to monitor. o Each facility typically has standard measurement containers for easy measuring. Copyright © 2021 Wolters Kluwer All Rights Reserved Body weight ❖ Daily weights often ordered for those at risk for ECF volume problems ❖ Obtain at the same time of day (0ereferly early a.m.) ❖ Wear similar clothing & use same scale to ensure accuracy ❖ May use bed scale if can’t stand ❖ Weight and I&O data are used together to evaluate for ECF imbalances. Copyright © 2021 Wolters Kluwer All Rights Reserved Integumentary assessment ❖ General appearance is important o A change is skin and/or mucous membranes can indicate fluid imbalance. ❖ Skin turgor o Assesses the amount of fluid in skin. Observing how quickly skin return to original position after pinching a small area of skin. ❖ Edema o Quantified using a 0-4 + scale ❖ Ascites o Accumulation of fluid in the abdominal cavity Copyright © 2021 Wolters Kluwer All Rights Reserved Vital signs ❖ Important parameters to monitor to detect potential fluid, electrolytes, and acid-base imbalances. ❖ Review normal vital sign parameters if needed Copyright © 2021 Wolters Kluwer All Rights Reserved Neck veins ❖ Distention of neck veins (Jugular veins) occurs with ECF excess (can be a sign of heart failure) ❖ To assess JVD: o Place pt is sitting position with HOB elevated to 45 degrees o The neck should be straight in alignment with the rest of body o The distention within the jugular vein should not extend more that 2cm above sternal angle. o An increase in ECF may be indicated by distention of the neck veins from the top portion of the sternum to the angle of the jaw Copyright © 2021 Wolters Kluwer All Rights Reserved Central venous pressure ❖ Measures pressure in right atrium or vena cava. ❖ Measured by adding a transducer to a central venus catheter (usually done in ICU setting) ❖ More accurate evaluation of fluid status than visual inspection of JVD ❖ Increase in pressure: May be ECF volume excess of heart failure ❖ Decrease in Pressure: May be ECF volume deficit Copyright © 2021 Wolters Kluwer All Rights Reserved Bowel assessment ❖ Access bowel activity o diarrhea (predisposes ECF volume disorders and electrolyte imbalances) o Constipation o Hypo or hyperactivity of bowel sounds should be noted Copyright © 2021 Wolters Kluwer All Rights Reserved Assessment: Laboratory and Diagnostic Tests ❖ Serum electrolytes(potassium, calcium, magnesium, etc) ❖ Plasma osmolality ( Normal between 280-300 mOsm/kg) ❖ Urine osmolality (Measures urines solute concentration) ❖ Urine specific gravity (should correlate with urine osmolarity) ❖ Arterial blood gases (Used to evaluate acid-base balances & pulmonary function). Evaluate trends rather than single values and carefully identify early changes Copyright © 2021 Wolters Kluwer All Rights Reserved Possible Nursing Diagnoses ❖ Excess Fluid Volume ❖ Deficient Fluid Volume Copyright © 2021 Wolters Kluwer All Rights Reserved Outcome Identification and Planning ❖ Reestablishment of normal ECF volume, water, or electrolyte balance ❖ Demonstration of knowledge regarding how to promote (or prevent) future ECF volume, water, or electrolyte balance ❖ Remaining free of complications from fluid or electrolyte imbalance Copyright © 2021 Wolters Kluwer All Rights Reserved Implementation: Health Promotion ❖ A primary teaching point is that the type of fluid replacement that the patient uses should be matched to the type of fluid that is being lost. ❖ New parents need to know how quickly serious problems can develop if vomiting, diarrhea, or a fever occurs in an infant. ❖ Fluid replacement in children can include commercially prepared electrolyte solutions or, in the case of short- term fluid loss, a homemade solution. ❖ Adequate water and electrolyte intake before, during, and after strenuous exercise is important. Copyright © 2021 Wolters Kluwer All Rights Reserved Interventions for Altered Fluid, Electrolyte, and/or Acid–Base Status ❖ Oral fluids o Increasing oral fluids o Restricting oral fluids ❖ Electrolyte replacement o Diet teaching o Electrolyte supplements ❖ Intravenous therapy Copyright © 2021 Wolters Kluwer All Rights Reserved Home and Community Care ❖ Dietary changes ❖ Medications ❖ Safe home environments ❖ Reportable signs/symptoms Copyright © 2021 Wolters Kluwer All Rights Reserved