Fluid and Electrolytes PDF

Introduction to Fluid and Electrolytes NURS 1060: Exam 3 1 OUTCOME u Describe principles of safe, patient-centered, evidence- based nursing care to adults at the basic level, guided by the Caritas philosophy. u Discuss critical thinking an...

Introduction to Fluid and Electrolytes NURS 1060: Exam 3 1 OUTCOME u Describe principles of safe, patient-centered, evidence- based nursing care to adults at the basic level, guided by the Caritas philosophy. u Discuss critical thinking and clinical reasoning to provide quality patient care. 2 COMPETENCY u Describe factors that create a culture of safety related to medication administration. u Discuss critical thinking and clinical judgment used to provide accurate and safe medication administration. 3 CONCEPT u Fluid and Electrolyte: The physiological mechanisms that maintain fluid and electrolyte balance that promote bodily functions. 4 Unit Outcomes u Discuss the role of body fluids and electrolytes in maintaining homeostasis. u Describe the processes involved in the movement of water and electrolytes between the fluid compartments. u Describe the composition and indications of common IV fluid solutions. 5 Normal Physiology u Maintenance of homeostasis u Composition of fluids and electrolytes kept within narrow limits of normal u Water content varies with age, gender, and fat content Body fluids and electrolytes play an important role in maintaining homeostasis, the stable internal environment of the body. Body fluids play an important role in transporting nutrients, electrolytes, and oxygen to cells as well as carrying waste products away from cells. The body uses several adaptive responses to maintain the composition of fluids and electrolytes within narrow limits of normal to maintain homeostasis. Various disease processes can affect fluid and electrolyte balance. It is important for nurses to be astute and carefully monitor patients for any changes. Water content in an adult constitutes 50% to 60% of body weight. This percentage decreases to 45% to 65% in the older adult, putting the elderly population at a higher risk for fluid imbalances. The more fat content in the body, the less amount of water. Because men typically have leaner muscle mass, they have a higher percentage of water than women. Conversely, obese people have a lower percentage of water content. 6 Normal Physiology u Body fluids and electrolytes maintain homeostasis, the stable internal environment of the body. u Body fluids play an important role in transporting nutrients, electrolytes, and oxygen to cells as well as carrying waste products away from cells. u Water content in an adult constitutes 50% to 60% of body weight. This percentage decreases to 45% in the older adult, putting the older adult population at a higher risk for fluid imbalances. u The more fat content in the body, the less amount of water. Leaner muscle mass has a higher percentage of water. 7 Body Water Over the Lifespan 8  Fluid Compartments Intracellular fluid (ICF) body water located within cells Extracellular fluid (ECF) body water is located outside the cells Interstitial fluid refers to fluid located in the spaces between the cells and lymph Intravascular (plasma) fluid refers to the fluid portion of blood, which is plasma Transcellular These include cerebrospinal fluid; fluid in the gastrointestinal (GI) tract; and pleural, synovial, peritoneal, intraocular, and pericardial fluid. Approximately two thirds of the body water is located within cells and is termed intracellular fluid (ICF). The other one third of body water is located outside the cells and is termed extracellular fluid (ECF). The extracellular fluid consists of three types of fluid: Interstitial fluid refers to fluid located in the spaces between the cells and lymph. Intravascular fluid refers to the fluid portion of blood, which is plasma. Transcellular fluid refers to a very small amount of fluid contained within specialized cavities of the body: These include cerebrospinal fluid; fluid in the gastrointestinal (GI) tract; and pleural, synovial, peritoneal, intraocular, and pericardial fluid. About two thirds of ECF is in the interstitial space and one third is intravascular. The fluid in the transcellular spaces totals about 1 L at any given time, but because 3L to 6L of fluid is secreted into and reabsorbed from the GI tract every day, loss of this fluid from vomiting or diarrhea can produce serious fluid and electrolyte imbalances. 9 Electrolytes u Substances whose molecules dissociate into ions u Ions are electrically charged particles u Cation and anion combine within the body fluids to maintain electroneutrality Ions are electrically charged particles. Cations are positively charged ions. Examples include sodium (Na+), potassium (K+), calcium (Ca2+), and magnesium (Mg2+) ions. Anions are negatively charged ions. Examples include bicarbonate (HCO3–), chloride (Cl–), and phosphate (PO43–) ions. A cation and anion combine within the body fluids to maintain electroneutrality. Examples include sodium bicarbonate (NaHCO3), sodium chloride (NaCl), and potassium chloride (KCl). 10 Electrolytes Cations: Examples: sodium (Na+), potassium (K+), calcium positively (Ca2+), and magnesium (Mg2+) ions charged Anions: Examples: bicarbonate (HCO3–), chloride (Cl–), and negatively phosphate (PO43–) ions charged 11 Mechanisms Controlling Fluid and Electrolyte Movement u Diffusion u The movement of molecules from an area of high concentration to one of low concentration. Movement stops when the concentration equalizes (see next slide). u Facilitated diffusion involves the use of a protein carrier in the cell membrane to move molecules that cannot otherwise pass through the membrane. Example: Glucose transport into the cell is facilitated diffusion.. Many different processes are involved in the movement of electrolytes and water between the ICF and ECF. Diffusion is the movement of molecules from an area of high concentration to one of low concentration (see next slide). The membrane that the molecules diffuse through must be permeable to the diffusing substances. The net movement of molecules stops when the concentrations are equal on both sides of semipermeable membrane. Diffusion is passive and requires no energy other than that of the concentration gradient. Facilitated diffusion involves the use of a protein carrier in the cell membrane to move molecules that cannot otherwise pass through the membrane. Glucose transport into the cell is an example of facilitated diffusion. A carrier molecule on most cells increases or facilitates the rate of diffusion of glucose into these cells. 12 Diffusion This visual demonstrates diffusion—the movement of molecules from an area of higher concentration to an area of lower concentration. Movement stops when the concentration equalizes. 13  u Active transport u Process in which molecules Mechanisms move against concentration gradient from an area of low Controlling concentration to an area of high concentration. Fluid and u Example: sodium-potassium Electrolyte pump. ATP is used to move sodium out of the cell and Movement potassium into the cell. Active transport uses external energy to move molecules against the concentration What is the difference between diffusion and active tranProcess in which molecules move against concentration gradient from an area of low concentration to an area of high concentration. sport??? 14 Sodium-Potassium Pump ATP is used to move sodium out of the cell and potassium into the cell 15 Mechanisms Controlling Fluid and Electrolyte Movement u Osmosis u Movement of water against concentration gradient u Water moves from the less concentrated side (has more water-less solute) to the more concentrated side (has less water- more solute) Osmosis is the movement of water through a semipermeable membrane that does not allow solutes to cross. Water moves from the less concentrated side (has more water) to the more concentrated side (has less water). Requires no energy. Water movement stops when the concentration differences disappear, or hydrostatic pressure builds sufficiently to oppose any further movement of water. 16 Osmosis Note the movement of water from one side to the other until the concentration of solutes is equal. 17 Osmolality or Tonicity Solutions in which solutes are more concentrated than Hypertonic the cells Solutions with the same osmolality, or tonicity, as the Isotonic cell interior Solutions in which the solutes are less concentrated than Hypotonic the cells 18 Effects of Water Status on RBC u A visual to understand the impact of tonicity on fluid movement is to picture what may happen to red blood cells when you administer different IV fluids. u Isotonic fluids have no impact on the red blood cells. u If a cell is surrounded by hypotonic fluid, water moves into the cell, causing it to swell and possibly to burst. u If a cell is surrounded by hypertonic fluid, water leaves the cell to dilute the ECF; the cell shrinks and eventually may die. 19 Effects of Water Status on RBC An easy visual to understand the impact of tonicity on fluid movement is to picture what may happen to red blood cells when you administer different IV fluids. Isotonic fluids have no impact on the red bloods cells. If a cell is surrounded by hypotonic fluid, water moves into the cell, causing it to swell and possibly to burst. If a cell is surrounded by hypertonic fluid, water leaves the cell to dilute the ECF; the cell shrinks and eventually may die. 20  Capillary hydrostatic pressure and Fluid interstitial oncotic pressure move water out of the capillaries into tissue Exchange Plasma oncotic pressure and interstitial Between hydrostatic pressure move fluid into the capillaries Capillary and If there are changes in capillary or interstitial Tissue pressures, fluid may shift abnormally from one compartment to another, resulting in either edema or dehydration. Hydrostatic pressure (arterial blood pressure or venous blood pressure) Hydro- = water Static- = force, pressure 21  Plasma-to-interstitial fluid shift results in edema When capillary hydrostatic pressure rises, fluid shifts into the interstitial space and causes edema. Fluid Shifts Interstitial fluid to plasma decreases edema When plasma oncotic pressures increase, fluid is drawn from the Interstitial space into the plasma space. This can occur with administration hypertonic solutions. When capillary hydrostatic pressure rises (increase in blood pressure, increase in blood volume), plasma oncotic pressure decreases, or interstitial oncotic pressure rises, fluid shifts into the interstitium and causes edema. Edema may also develop if an obstruction of lymphatic outflow causes decreased removal of interstitial fluid. When plasma oncotic pressures increase, fluid is drawn from the interstitium into the plasma space. This can occur with administration of colloids, dextran, mannitol, or hypertonic solutions. Additionally, an increase in tissue hydrostatic pressure can cause a shift of fluid into the plasma. The application of elastic compression gradient stockings to decrease peripheral edema is a therapeutic application of this effect. 22 Fluid Exchange Between Capillary and Tissue 23 Exchange of Blood to tissue with oxygen and nutrients and electrolytes Nutrients and Waste Tissue to blood with carbon Summary dioxide and waste This balance and shift of fluid allows the exchange of nutrients and waste 24  First spacing Second spacing Third spacing Normal distribution of Abnormal: Abnormal: Third- fluid in the ICF and ECF accumulation of spaced fluid is trapped compartments interstitial fluid and unavailable for (edema) functional use. Example: Ascites- accumulation of fluid in the peritoneal cavity Fluid Spacing Fluid spacing: the distribution of body water First spacing: the normal distribution of fluid in the ICF and ECF compartments Second spacing: an abnormal accumulation of interstitial fluid (i.e., edema) Third spacing: when fluid accumulates in a portion of the body from which it is not easily exchanged with the rest of the ECF. Third-spaced fluid is trapped and unavailable for functional use. Ascites is an example of third-spaced fluid. 25  Hypothalamic-pituitary regulation Regulation of Renal regulation Water Adrenal cortical regulation Balance Insensible water loss 26 Regulation of Water Balance Hypothalamic-Pituitary regulation u Receptors in hypothalamus sense fluid deficit or increase u Deficit stimulates thirst and antidiuretic hormone (ADH) release from the pituitary gland u Water excess suppresses ADH release An intact thirst mechanism is critical because it is the primary protection against the development of hyperosmolality. Osmoreceptors in the hypothalamus sense a body fluid deficit or increase in plasma osmolality, which in turn stimulates thirst and antidiuretic hormone (ADH) release. Thirst causes the patient to drink water. ADH (also called vasopressin), which is synthesized in the hypothalamus and stored in the posterior pituitary, acts in the renal distal and collecting tubules causing water reabsorption. If the plasma osmolality is decreased or there is water excess, secretion of ADH is suppressed, resulting in urinary excretion of water. 27 Regulation of Water Balance Renal Regulation u Primary organs for regulating fluid and electrolyte balance u Adjusting urine volume u Selective reabsorption of water and electrolytes u Renal tubules are sites of action of ADH and aldosterone u In the average adult, the kidney produces approximately 1.5 L of urine per day. u Minimum amount required for RENAL FUNCTION = 30 ml/hr u With severely impaired renal function, the kidneys cannot maintain fluid and electrolyte balance- results in edema, potassium and phosphorous retention, acidosis, and other electrolyte imbalances. The kidneys regulate water balance by adjusting urine volume and the urinary excretion of most electrolytes to maintain a balance between overall intake and output. In the average adult, the kidney reabsorbs 99% of this filtrate, producing approximately 1.5 L of urine per day. With severely impaired renal function, the kidneys cannot maintain fluid and electrolyte balance. This condition results in edema, potassium and phosphorous retention, acidosis, and other electrolyte imbalances. 28 Regulation of Water Balance Adrenal Cortical Regulation u Releases hormones to regulate water and electrolytes u Mineral Corticoids- Aldosterone causes sodium retention and potassium excretion. Water is retained with sodium. u Decreased renal perfusion to the distal portion of the renal tubule activates the renin-angiotensin-aldosterone system (RAAS) Glucocorticoids and mineralocorticoids secreted by the adrenal cortex help regulate both water and electrolytes. The glucocorticoids (e.g., cortisol) primarily have an anti-inflammatory effect and increase serum glucose levels. The mineralocorticoids (e.g., aldosterone) cause sodium retention and potassium excretion. Water is retained with sodium. In large doses, cortisol has both glucocorticoid (glucose-elevating and anti- inflammatory) and mineralocorticoid (sodium-retention) effects. Cortisol is normally secreted in a diurnal, or circadian, pattern and also in response to increased physical and psychologic stress. Many body functions, including fluid and electrolyte balance, are affected by stress. Decreased renal perfusion or decreased sodium delivery to the distal portion of the renal tubule activates the renin-angiotensin-aldosterone system (RAAS), which results in aldosterone secretion. Increased serum potassium, decreased serum sodium, and release of adrenocorticotropic hormone (ACTH) from anterior pituitary gland also stimulate release of aldosterone. What could cause decreased renal perfusion??? 29 30 Regulation of Water Balance Insensible Water Loss u Invisible vaporization from lungs and skin u Loss of approximately 600 to 900 mL/day u No electrolyte loss u Excessive sweating (sensible perspiration) caused by exercise, fever, or high environmental temperatures may lead to large losses of water and electrolytes. Insensible water loss is the invisible vaporization from the lungs and skin that helps regulate body temperature. Normally, about 600 to 900 mL/day is lost. Accelerated body metabolism, which occurs with increased body temperature and exercise, increases the amount of water loss. Insensible perspiration causes only water loss. Excessive sweating (sensible perspiration) caused by exercise, fever, or high environmental temperatures may lead to large losses of water and electrolytes. 31 I+O u Fluid intake u 2,500 – 3,000 mL/day at moderate activity and temperature u Food contributes u Thirst regulator in hypothalamus u Fluid output u 1,400–1,500 mL/day of urine u 30 ml/hr minimum u Insensible loss through skin and lungs u Feces 32 Genetic and Lifespan Considerations Suggested Average sodium sodium intake intake in the is ≤1,500–2,300 United States is mg/day >3,400 mg/day 33 Gerontological Considerations Structural changes in kidneys decrease ability to conserve water Hormonal changes lead to decrease in renin and aldosterone and increase in ADH Loss of subcutaneous tissue leads to increased loss of moisture Structural changes to the kidney and a decrease in the renal blood flow lead to a decrease in the glomerular filtration rate, decreased creatinine clearance, and the loss of ability to concentrate urine and conserve water. Hormonal changes include a decrease in renin and aldosterone and an increase in ADH and ANP. Loss of subcutaneous tissue and thinning of the dermis lead to increased loss of moisture through the skin and an inability to respond to heat or cold quickly. 34  Gerontological Considerations Reduced thirst mechanism results in decreased fluid intake Functional changes affect ability to independently obtain fluids Musculoskeletal changes, such as stiffness of the hands and fingers, can lead to a decreased ability to hold a glass or cup. Older adults experience a decrease in the thirst mechanism resulting in decreased fluid intake despite increases in osmolality and serum sodium level. Musculoskeletal changes, such as stiffness of the hands and fingers, can lead to a decreased ability to hold a glass or cup. Mental status changes, such as confusion or disorientation, or changes in ambulation status may lead to a decreased ability to obtain fluids. To reduce incontinent episodes, the older adult may intentionally restrict fluid intake. Do not automatically attribute older patients’ fluid and electrolyte problems to the natural processes of aging. Adapt your assessment and nursing interventions to account for these physiologic and functional changes. 35 Gerontological Considerations Mental status changes, such as confusion or disorientation, or changes in ambulation status may lead to a decreased ability to obtain fluids. To reduce incontinent episodes, the older adult may intentionally restrict fluid intake. All of these factors put the older adult at risk for fluid deficit. 36 IV Fluids Overview u Purposes u Maintenance u When oral intake is not adequate u Replacement u When losses have occurred u Types of fluids categorized by tonicity u Tonicity (osmotic pressure of fluid related to the concentration of electrolytes in fluid) is important when correcting water and solute imbalances. u Fluids are classified as hypotonic, isotonic, and hypertonic IV fluid and electrolyte therapy is necessary to treat many different fluid and electrolyte imbalances. Many patients need maintenance IV fluid therapy while they cannot take oral fluids (e.g., during and after surgery). Other patients need corrective or replacement therapy for losses that have already occurred. The amount and type of solution are determined by the normal daily maintenance requirements and by imbalances identified by laboratory results. Tonicity (osmotic pressure of fluid related to the concentration of electrolytes in fluid) is important when correcting water and solute imbalances. Fluids are classified as hypotonic, isotonic, and hypertonic (described in next three slides). 37 Apply your Knowledge Question u Since 0.9% Sodium Chloride (Normal Saline) is an isotonic solution: u What is 0.45% Sodium Chloride? ________________ u What is 3% Sodium Chloride? ________________ 0.45 % Sodium Chloride is hypotonic 3% Sodium Chloride is hyper tonic 38 IV Fluids by Tonicity Hypotonic More water than electrolytes dilutes the ECF Usually maintenance fluids Maintenance fluids are usually hypotonic solutions because normal daily losses are hypotonic. EXAMPLE: 0.45% sodium chloride Monitor for changes in LOC Because hypotonic solutions have the potential to cause cellular swelling, monitor patients for changes in mental status (confusion, lethargy) that may indicate cerebral edema A hypotonic solution provides more water than electrolytes, diluting the ECF. Osmosis then produces a movement of water from the ECF to the ICF. After achieving osmotic equilibrium, the ICF and the ECF have the same osmolality, and both compartments are expanded. Maintenance fluids are usually hypotonic solutions (e.g., 0.45% NaCl) because normal daily losses are hypotonic. Additional electrolytes (e.g., KCl) may be added to maintain normal levels. Because hypotonic solutions have the potential to cause cellular swelling, monitor patients for changes in mentation that may indicate cerebral edema. https://gifs.com/gif/half-normal-saline-1rDVy3 39 IV Fluids by Tonicity Isotonic Administration of an isotonic solution expands only the ECF. Example: 0.9% Sodium Chloride An isotonic solution is the ideal fluid replacement for a patient with an ECF volume deficit.. Administration of an isotonic solution expands only the ECF. There is no net loss or gain from the ICF. An isotonic solution is the ideal fluid replacement for a patient with an ECF volume deficit. 40 IV Fluids by Tonicity Hypertonic A hypertonic solution initially raises the osmolality of ECF and expands it higher osmotic pressure draws water out of the cells into the ECF. Useful in the treatment of hypovolemia and hyponatremia. Example: 3% Sodium Chloride Hypertonic solutions require monitoring of: blood pressure, lung sounds, and serum sodium levels because of the risk for intravascular fluid volume excess. A hypertonic solution initially raises the osmolality of ECF and expands it. In addition, the higher osmotic pressure draws water out of the cells into the ECF. It is useful in the treatment of hypovolemia and hyponatremia. Hypertonic solutions require frequent monitoring of blood pressure, lung sounds, and serum sodium levels because of the risk for intravascular fluid volume excess. 41 Types of IV Fluids 42 Normal Saline (NS) u Isotonic u Expands Circulating Volume u Preferred fluid for immediate response u Risk for fluid overload higher u Compatible with most medications u Emergency Situation administer NS Isotonic saline (0.9% NaCl) has a sodium concentration (154 mEq/L) somewhat higher than plasma (135 to 145 mEq/L) and a chloride concentration (154 mEq/L) significantly higher than the plasma chloride level (96 to 106 mEq/L). Thus, excessive administration of isotonic NaCl can result in elevated sodium and chloride levels. Normal saline is used to expand intravascular volume and replace extracellular fluid losses. Can cause intravascular fluid overload and hyperchloremic acidosis. 43 D5W (5% Dextrose in Water) u Not enough to meet caloric requirements u One liter of a 5% dextrose solution provides 50 g of dextrose, or 170 calories u Isotonic initially but becomes hypotonic as dextrose is quickly metabolized by the cells and free water remains u Free water increases renal excretion u Used to replace water losses and treat Hypernatremia (will discuss later) u Does not provide electrolytes Although 5% dextrose in water is considered an isotonic solution, the dextrose is quickly metabolized, and the net result is the administration of free water (hypotonic) with proportionately equal expansion of the ECF and ICF. One liter of a 5% dextrose solution provides 50 g of dextrose, or 170 calories. Although this amount of dextrose is not enough to meet caloric requirements, it helps prevent ketosis associated with starvation. D5W provides free water necessary for renal excretion of solutes and is therefore used to replace water losses and to treat hypernatremia. It does not replace any electrolytes. 44 Lactated Ringer’s (LR) Solution u Isotonic u LR contains sodium, potassium, chloride, calcium, and lactate (the precursor of bicarbonate) u NO Magnesium. u Expands ECF—treat burns and GI losses u Contraindicated with hyperkalemia u Why? Lactated Ringer’s solution contains sodium, potassium, chloride, calcium, and lactate (the precursor of bicarbonate) in about the same concentrations as those of the ECF. It does not contain magnesium. It is used to treat losses from burns and lower GI tract. It is contraindicated in the presence of hyperkalemia and lactic acidosis because, in these conditions, the body has a decreased ability to convert lactate to bicarbonate. It does not contain any free water or calories. 45 Dextrose 5% and 0.45% Sodium Chloride (D5 ½ NS) u Hypertonic u Free water in addition to Na+ and Cl- u Common maintenance fluid u Replaces fluid loss u Does not replace other electrolyte only sodium u Manufactured Premixed 1,000 ml IV bags with added K+ (20mEq and 40mEq are typical) u D5 ½ NS 20mEq KCL D5 ½ NS 40mEq KCL D5 ½ NS is a hypertonic solution that provides free water in addition to Na+ and Cl-. It is used to replace fluid loss and as maintenance solution. It does not replace daily loss of other electrolytes—need to add K+ if needed. 46 1060 Pharmacology Lecture: Exam 3 u Format: Multiple Choice or Select All That Apply (45 questions) u Time: 68 minutes (1.5 minutes per question) u Covers all 1060 content including: u PowerPoints from Lecture u Drug Interactions u Nursing Process in Pharmacology u Antiseptics and Disinfectants u Introduction to Fluid and Electrolytes u In-class activities, study guides and homework 47