Presentation on theme: "Fluids and Electrolytes"— Presentation transcript:
1Fluids and Electrolytes Chapter 14Fluids and Electrolytes
2HomeostasisMaintaining relatively constant conditions as in fluid compartmentsTo maintain internal balance, body must be able to regulate fluidsAll organs and structures of the body involved in homeostasisWhat percent of the human body is composed of water?Homeostasis is necessary for cells to be able to carry out their work.Body fluids are in constant motion, maintaining healthy living conditions for body cells.The process of homeostasis involves the delivery of essential elements such as oxygen and glucose to the cells and the removal of wastes such as carbon dioxide from the cells.When the body does not maintain homeostasis, the cells cannot function properly, and illness results.
3Homeostasis cont’d Intracellular fluid Extracellular fluid Fluid within a cellMost of the body’s fluids found within the cellExtracellular fluidFluid outside the cellIntravascular fluidIn blood vessels in the form of plasma or serumInterstitial fluidIn fluid surrounding cells, including lymphWhich fluid is mainly responsible for the transport of nutrients and wastes throughout the body?
4Water Largest portion of body weight Percentage affected by age, sex, body fatPercentage of body water decreases with ageFemales have a lower percentage of body water than males throughout adult years because women have more fat than men and fat cells contain less water than other cellsObese have a lower percentage of body water because of the increased number of fat cells
5SolutesElectrolyteSubstance that develops an electrical charge when dissolved in waterExamples: sodium, potassium, calcium, chloride, bicarbonate, and magnesiumMaintain balance between positive and negative chargesFor every positively charged cation, there is a negatively charged anionCations and anions combine to balance one anotherHow is the concentration of an electrolyte in a solution or body fluid compartment measured?Hydrogen is used as a standard for comparing the chemical activities of electrolytes.
6Solutes cont’d Sodium (Na) Most abundant electrolyte; primary electrolyte in extracellular fluidMajor role in regulating body fluid volumes, muscular activity, nerve impulse conduction, and acid-base balance
7Solutes cont’d Potassium (K) Found mainly in the intracellular fluid; the major intracellular cationImportant in maintaining fluid osmolarity and volume within the cellEssential for normal membrane excitability— a critical factor in transmitting nerve impulsesNeeded for protein synthesis, for the synthesis and breakdown of glycogen, and to maintain plasma acid-base balance
8Solutes cont’d Chloride (Cl) An extracellular anion that is usually bound with other ions, especially sodium or potassiumFunctions are to regulate osmotic pressure between fluid compartments and assist in regulating acid-base balance
9Solutes cont’d Calcium (Ca) Usually combined with phosphorus to form the mineral salts of the bones and teethOf total body calcium, 99% concentrated in the bones and teeth; 1% is in the extracellular fluidIngested through the diet and absorbed through the intestinePromotes transmission of nerve impulses; helps regulate muscle contraction and relaxationHow does calcium regulation take place in the body?
10Solutes cont’d Magnesium (Mg2+) A cation found in bone (50% to 60%), intracellular fluid (39% to 49%), and extracellular fluid (1%)Plays a role in the metabolism of carbohydrates and proteins, the storage and use of intracellular energy, and neural transmissionImportant in heart, nerve, and muscle functionHow much of the magnesium ingested through the diet is absorbed?Magnesium is excreted through the kidneys, and the rate of excretion is regulated by sodium and calcium excretion, extracellular ﬂuid volume, and parathyroid hormone.
11Solutes cont’d Nonelectrolytes Other substances dissolved in the body fluidsUrea, protein, glucose, creatinine, and bilirubinThese solutes do not carry an electrical charge
12Transport of Water and Electrolytes MembranesSelectively permeable membranesSeparate fluid compartments and control movement of water and certain solutesMaintain unique composition of each compartment of the body while allowing transport of nutrients and wastes to and from cellsSome solutes cross membranes more easily than othersWhat is an example of selective permeability?Small molecules and water move freely across membranes, whereas larger molecules such as protein move less readily.
13Transport Processes Diffusion The random movement of particles in all directionsis for a substance to move from an area of higher natural tendency concentration to an area of lower concentrationFacilitated diffusionA carrier protein transports the molecules through membranes toward an area of lower concentration
14Transport Processes cont’d Active transportCarrier proteins transport substances from an area of lower concentration to an area of equal or greater concentrationRequires expenditure of energyMany solutes, such as sodium, potassium, glucose, and hydrogen, are actively transported across cell membranesHow does a sodium pump function?
15Transport Processes cont’d FiltrationTransfer of water and solutes through a membrane from an area of high pressure to an area of low pressureHydraulic pressureA combination of pressures from the force of gravity on the fluid and the pumping action of the heartNeeded to move fluid out of capillaries into tissues and filter plasma through the kidneys
16Transport Processes cont’d OsmosisMovement across a membrane from a less concentrated to a more concentrated solutionInvolves movement of water only; sometimes force of movement across membrane carries solutes alongIf a fluid compartment has less water and more sodium, water from another compartment moves to the more concentrated compartment by osmosis to create a better fluid balance
17OsmolalityConcentration of solution determined by number of dissolved particles per kg waterControls water movement and distribution by regulating the concentration of fluid in each body fluid compartmentThe osmolality of intracellular fluid and extracellular fluid tends to equalize because of the constant shifting of waterA higher osmolality means there is a higher concentration of a solute in the water because the solution contains less water.What is the normal osmolality of body fluid?Osmolarity refers to the concentration of particles per liter of solution.
19Kidneys Main regulators of fluid balance Control extracellular fluid by adjusting the concentration of specific electrolytes, osmolality of body fluids, the volume of extracellular fluid, blood volume, and pHThe nephron is the functioning unit of the kidneyGlomerulus is the filtering portion of the nephron, and the tubule is responsible for secretion and reabsorptionNephrons conduct work of the kidney through filtration, reabsorption, and secretion
20Kidneys cont’d Filtration Blood plasma entering the kidney via the renal artery is delivered to the glomerulusAbout 20% of plasma filtered into glomerular capsuleMost remaining plasma leaves kidney through the renal veinFiltrate then moves through the tubules, where it is transformed into urine by tubular reabsorption and secretion
21Kidneys cont’d Tubular reabsorption A process by which most of the glomerular filtrate is returned to the circulationWater and selected solutes move from the tubules into the capillariesWaste products remain in tubules for excretion, whereas most water and sodium is reabsorbed into the bloodstreamAdjusts volume and composition of the filtrate; prevents excessive fluid loss through kidneys
22Kidneys cont’d Tubular secretion The last phase in the work of the kidneysThe filtrate is transformed into urineVarious substances—drugs, hydrogen ions, potassium ions, creatinine, and histamine—pass from the blood into the tubulesProcess eliminates some excess substances to maintain fluid and electrolyte balance, as well as metabolic waste products
23Hormones Renin Aldosterone Hormone secreted when blood volume or blood pressure fallsCauses the release of aldosterone with subsequent sodium and water retentionAldosteroneActs on kidney tubules to increase reabsorption of sodium and decrease reabsorption of potassiumBecause the retention of sodium causes water retention, aldosterone acts as a volume regulator
24Hormones cont’d Antidiuretic hormone (ADH) Causes capillaries to reabsorb more water, so urine is more concentrated and less volume is excretedAtrial natriuretic factor (ANF)Hormone released by the atria in response to stretching of the atria by increased blood volumeStimulates excretion of sodium and water by the kidneys, decreased synthesis of renin, decreased release of aldosterone, and vasodilationReduces blood volume and lowers blood pressureWhere is ADH produced?An increase in plasma osmolality stimulates the release of ADH into the bloodstream to replenish needed fluid in the body.
25Thirst Regulates fluid intake Increased plasma osmolality stimulates osmoreceptors in the hypothalamus to trigger the sensation of thirstMore sodium and less water in the body make a person thirstyAdditional fluids consumed; kidneys conserve water until osmolality returns to normal
26Regulation of body fluid volume depends on aldosterone, antidiuretic hormone (ADH), and thirst.
27Fluid Gains and LossesIn healthy adult, 24-hour fluid intake and output approximately equalFluids gained by drinking and eating and lost through the kidneys, skin, lungs, and gastrointestinal tractThe usual adult urine volume is between 1 and 2 L/day, or 1 ml/kg of body weight per hourIn kidneys, water loss varies largely with the amount of solute excreted and with the level of antidiuretic hormone
28Fluid Gains and Losses cont’d Losses through the skin occur by sweatingWater loss through the lungs by evaporation at 300 to 400 ml/dayIn the gastrointestinal tract, the usual loss of fluid is about 100 to 200 ml/dayWhere is the bulk of fluid secreted into the GI tract reabsorbed?
29Age-Related Changes Affecting Fluid Balance Aging kidney slower to adjust to changes in acid-base, fluid, and electrolyte balancesOlder adult often has a reduced sense of thirst and therefore may be in a state of chronic dehydrationTotal body water declines with age; greatest loss from the intracellular fluid compartment
30Age-Related Changes Affecting Fluid Balance cont’d Older person has limited reserves to maintain fluid balance when abnormal losses occurAntihypertensives, diuretics, and antacids can also contribute to imbalancesUnless contraindicated, fluid requirements for older adults, based on ideal body weight, are30 ml/kg for ages 55 to 65 and 25 ml/kg for 65 years and olderWhat symptoms may occur in the older adult with fluid imbalances?Chronic conditions that affect mobility or mental status may interfere with adequate fluid intake.
31Assessment of Fluid and Electrolyte Balance Health historyDetermines if patient has conditions that contribute to fluid or electrolyte imbalancesVomiting, diarrhea, kidney diseases, diabetes, salicylate poisoning, burns, congestive heart failure, cerebral injuries, ulcerative colitis, and hormonal imbalances; the intake of drugs, such as diuretics and cathartics; and medical interventions, such as gastric suctioningComplaints of fatigue, palpitations, dizziness, edema, muscle weakness or cramps, dyspnea, and confusion may be associated with fluid imbalances
32Assessment of Fluid and Electrolyte Balance cont’d Vital signsPulse, respiration, temperature, and blood pressure can indicate changes in fluid and electrolyte balance.Temperature variations can be associated with fluid volume excess or deficit.Pulse rate and quality may change in response to blood volume alterations; electrolyte changes can affect heart rate and rhythm. Blood pressure is directly related to blood volume. Respirations are minimally affected by electrolyte changes.Fever poses a risk of water and electrolyte loss associated with sweating and an increased metabolic rate.How should blood pressure be measured in the older adult?
33Assessment of Fluid and Electrolyte Balance cont’d Intake and outputAccurate records are essential to determine whether the patient’s intake is equal to outputAll fluids entering or leaving the body should be notedA changing urine output may reflect attempts by the kidneys to maintain or restore balance, or it may reflect a problem that causes fluid disturbancesUrine characteristics also give clues to fluid balanceClear, pale urine in a healthy person suggests the excretion of excess water, whereas darker, concentrated urine indicates the kidneys are retaining water
34Assessment of Fluid and Electrolyte Balance cont’d SkinCharacteristicsMoisture, turgor, and temperature reflect fluid balance. Dry, flushed skin—dehydration. Pale, cool, clammy skin—severe fluid volume deficit that occurs with shock. Moist, edematous tissue seen with excess fluid volumeFacial characteristicsSeverely dehydrated patient has a pinched, drawn facial expression. Soft eyeballs and sunken eyes indicate severely deficient fluid volume. Puffy eyelids and fuller cheeks suggest excess fluid volume
35Assessment of Fluid and Electrolyte Balance cont’d Skin turgorMeasured by pinching the skin over the sternum, the inner aspects of the thighs, or the foreheadIn patients who are dehydrated, skin flattens more slowly after the pinch is releasedEdemaReflects water and sodium retention, which can result from excessive reabsorption or inadequate secretion of sodium, as may occur with kidney failurePitting depression remains in the tissue after pressure is applied with a fingertipWhat does the term tenting mean?Pitting edema is evaluated on a four-point scale, ranging from +1 edema (barely detectable pit) to +4 edema (deep and persistent pit that is approximately 1 inch [2.54 cm] deep).
36Assessment of Fluid and Electrolyte Balance cont’d Mucous membranesTongue turgorIn well person, tongue has one longitudinal furrow. Fluid volume deficit causes additional longitudinal furrows, and the tongue is smaller. Sodium excess causes the tongue to appear red and swollen.Moisture of the oral cavityA dry mouth may be the result of deficient fluid volume or mouth breathing.VeinsAppearance of the jugular veins in the neck and the veins in the hands can suggest either a fluid volume deficit or excess.
37Diagnostic Tests and Procedures Urine studiesUrine pHDetermines if kidneys are responding appropriately to metabolic acid-base imbalancesUrine specific gravityA measure of urine concentrationA good indicator of fluid balanceOsmolalityMeasures the number of dissolved particles in a solutionProvides more precise measurement of kidneys’ ability to concentrate urineWhat is the normal pH of urine? Specific gravity? Osmolarity?Diet is a factor in that a person who consumes large amounts of citrus fruits and vegetables tends to have alkaline urine, whereas a person who eats a lot of meat tends to have acidic urine.The specific gravity also reflects renal function.Dilute urine has a low osmolality and generally reflects renal excretion of excess water.Concentrated urine has a high osmolality and generally indicates renal conservation of water.
38Diagnostic Tests and Procedures cont’d Urine creatinine clearance testsDetect glomerular damage in the kidneyA 24-hour specimen is requiredUrine sodiumSodium intake and fluid volume statusUrine potassiumA measure of renal tubular functionWhat instructions should the patient be given during a urine creatinine clearance test?Normal creatinine clearance for adult males is 85 to 125 mL/min/1.73 m2 of body surface area; for females, it is 75 to 115 mL/min/1.73 m2 of body surface area.The normal urine sodium is 75 to 200 mEq/L.The normal value is 25 to 123 mmol/24 hr.
39Diagnostic Tests and Procedures cont’d Blood studiesSerum hematocritPercentage of blood volume composed of red blood cellsSerum creatinineA metabolic waste productIndicator of renal functionBlood urea nitrogen (BUN)A measure of renal functionWhat is the normal range for hematocrit? Serum creatinine? Blood urea nitrogen?The serum creatinine level is a better indicator of renal function than the blood urea nitrogen.
40Diagnostic Tests and Procedures cont’d Serum albuminA plasma protein that helps maintain blood volume by creating colloid osmotic pressureSerum electrolytesSodium, potassium, chloride, and calciumLow serum albumin allows water to shift into the interstitial compartment, which reduces blood volume and creates edema.What is the normal range for serum albumin? Electrolytes?
41Fluid Imbalances Decreased intake, abnormal fluid losses, or both Deficient fluid volumeLess water than normal in the bodyIsotonic extracellular fluid deficitHypovolemiaHypertonic extracellular fluid deficitDehydrationDecreased intake, abnormal fluid losses, or bothExamples: loss of water from excessive bleeding, severe vomiting/diarrhea, severe burnsThe signs and symptoms of fluid volume deficit vary depending on how suddenly the deficit develops and how severe it is.What nursing diagnoses may be used for fluid volume deficit?
42Fluid Imbalances cont’d Excess fluid volumeAn increase in body waterExtracellular fluid excessIsotonic fluid excessIntracellular water excessHypotonic fluid excessFrom renal or cardiac failure with retention of fluid, increased production of antidiuretic hormone or aldosterone, overload with isotonic IV fluids, or administration of dextrose 5% in water (D5W) after surgery or traumaThe severity of the symptoms in fluid volume excess depends on how quickly the condition develops.Severe fluid volume excess can cause or aggravate heart failure and pulmonary edema.What nursing diagnoses may be used for fluid volume excess?
44Hyponatremia Lower than normal sodium in the blood serum Can be actual deficiency of sodium or increase in body water that dilutes the sodium excessivelyAssessmentSymptoms: headache, muscle weakness, fatigue, apathy, confusion, abdominal cramps, and orthostatic hypotensionTake blood pressures with the patient lying or sitting and then standing to determine if a significant dropWhat is syndrome of inappropriate antidiuretic hormone secretion (SIADH)?Disorders that put the patient at risk for hyponatremia include congestive heart failure, liver cirrhosis, and nephrotic syndrome.
45Hyponatremia cont’d Medical treatment Nursing care The usual treatment is restriction of fluids while the kidneys excrete excess waterDiuretic: furosemide (Lasix)Sodium replacement therapyNursing careAdminister prescribed medications and IV fluidsMeasure fluid intake and output and assess mental statusA balanced diet usually provides adequate sodium, but patients with moderate or severe hyponatremia may need sodium replacement therapy.How can you prevent hyponatremia in patients with feeding tubes?
46Hypernatremia Higher than normal concentration of sodium in the blood Very serious imbalance; can lead to death if not correctedOccurs when excessive loss of water or excessive retention of sodiumSigns and symptomsThirst, flushed skin, dry mucous membranes, low urine output, restlessness, increased heart rate, convulsions, and postural hypotensionWhat are some causes of hypernatremia?
47Hypernatremia cont’d Medical treatment Nursing care Oral or IV replacement of water to restore balanceA low-sodium diet often prescribedNursing careEncourage patients with hypernatremia to drink waterClosely monitor the infusion of IV fluidsTeach patient to track daily intake and output and to recognize the signs and symptoms of fluid retention or depletionWhat foods should be avoided for a patient on a low-sodium diet?
48Hypokalemia Low serum potassium May result in gastrointestinal, renal, cardiovascular, and neurologic disturbancesCan cause abnormal, potentially fatal, heart rhythmSigns and symptomsAnorexia, abdominal distention, vomiting, diarrhea, muscle cramps, weakness, dysrhythmias (abnormal cardiac rhythms), postural hypotension, dyspnea, shallow respirations, confusion, depression, polyuria (excessive urination), and nocturiaWhat are some causes of hypokalemia?The effect on myocardial cells is important because it tends to cause abnormal and potentially fatal heart rhythms.
49Hypokalemia cont’d Medical treatment Nursing care Potassium replacement by the IV or oral routeNursing careMonitoring at-risk patients for decreased bowel sounds, a weak and irregular pulse, decreased reflexes, and decreased muscle toneCardiac monitors may be used to detect dysrhythmiasAdminister oral or IV potassiumUrine output should be no less than 30 ml/hr
50Hyperkalemia High serum potassium Patients at risk: decreased renal function, in metabolic acidosis, taking potassium supplementsA serious imbalance because of the potential for life-threatening dysrhythmiasSigns and symptomsExplosive diarrhea and vomiting; muscle cramps and weakness, paresthesia, irritability, anxiety, abdominal cramps, and decreased urine outputPotassium is plentiful in common foods, so it is easy for people on normal diets to take in adequate amounts.How can traumatic injuries cause hyperkalemia?
51Hyperkalemia cont’d Medical treatment Nursing care Correct the underlying causeRestrict potassium intakePolystyrene sulfonate (Kayexalate)Intravenous calcium gluconateNursing carePatients with low urine output or those taking potassium-sparing diuretics must be monitored carefully for signs and symptomsCarefully monitor flow rate of IV fluids, which should not exceed 10 mEq/hr through peripheral veinsScreen the results of laboratory studiesTemporary effects may be obtained by the intravenous administration of insulin and glucose or sodium bicarbonate to promote the shifting of potassium into the cells.What instructions should be given to the patient taking potassium supplements?
56Chloride ImbalanceUsually bound to other electrolytes; therefore, chloride imbalances accompany other electrolyte imbalancesHyperchloremiaUsually associated with metabolic acidosisHypochloremiaUsually occurs when sodium is lost because chloride most frequently bound with sodium
57Calcium Imbalance Regulated by the parathyroid glands Hypocalcemia results from diarrhea, inadequate dietary intake of calcium or vitamin D, and multiple blood transfusions (banked blood contains citrates that bind to calcium), in addition to some diseases, including hypoparathyroidismHypercalcemia results from a high calcium or vitamin D intake, hyperparathyroidism, and immobility that causes stores of calcium in the bones to enter the bloodstream
59Magnesium ImbalanceHypomagnesemia: decreased gastrointestinal absorption or excessive gastrointestinal loss, usually from vomiting and diarrhea, or increased urinary lossHypermagnesemia occurs most often with excessive use of magnesium-containing medications or intravenous solutions in patients with renal failure or preeclampsia of pregnancy
64Respiratory AcidosisRespiratory system fails to eliminate the appropriate amount of carbon dioxide to maintain the normal acid-base balanceCaused by pneumonia, drug overdose, head injury, chest wall injury, obesity, asphyxiation, drowning, or acute respiratory failureMedical treatmentImprove ventilation, which restores partial pressure of carbon dioxide in arterial blood (Paco2) to normalWhat are the common clinical signs and symptoms of respiratory acidosis?Underlying respiratory conditions are treated to eliminate the cause of respiratory acidosis.
65Respiratory Acidosis cont’d Nursing careAssess Paco2 levels in the arterial bloodObserve for signs of respiratory distress: restlessness, anxiety, confusion, tachycardiaInterventionEncourage fluid intakePosition patients with head elevated 30 degreesPaco2 directly reflects the degree of respiratory dysfunction.
66Respiratory Alkalosis Low Paco2 with a resultant rise in pHMost common cause of respiratory alkalosis is hyperventilationMedical treatmentMajor goal of therapy: treat underlying cause of condition; sedation may be ordered for the anxious patientWhat aspect of the respirations is a key observation for a patient with respiratory alkalosis?Clinical signs and symptoms include increased respiratory and heart rates, an anxious appearance, irritability, dizziness, light-headedness, muscle weakness, and tingling or numbness of the fingers.
67Respiratory Alkalosis cont’d Nursing careInterventionIn addition to giving sedatives as ordered, reassure the patient to relieve anxietyEncourage patient to breathe slowly, which will retain carbon dioxide in the body
68Metabolic AcidosisBody retains too many hydrogen ions or loses too many bicarbonate ions; with too much acid and too little base, blood pH fallsCauses are starvation, dehydration, diarrhea, shock, renal failure, and diabetic ketoacidosisSigns and symptoms: changing levels of consciousness, headache, vomiting and diarrhea, anorexia, muscle weakness, cardiac dysrhythmiasMedical treatment: treat the underlying disorderSigns and symptoms vary according to the underlying cause and the severity of the acid-base disturbance.Mechanical ventilation may be necessary, especially in patients who are comatose.
69Metabolic Acidosis cont’d Nursing careAssessment of the patient in metabolic acidosis should focus on vital signs, mental status, and neurologic statusEmergency measures to restore acid-base balance. Administer drugs and intravenous fluids as prescribed. Reassure and orient confused patients
70Metabolic AlkalosisIncrease in bicarbonate levels or a loss of hydrogen ionsLoss of hydrogen ions may be from prolonged nasogastric suctioning, excessive vomiting, diuretics, and electrolyte disturbancesSigns and symptoms: headache; irritability; lethargy; changes in level of consciousness; confusion; changes in heart rate; slow, shallow respirations with periods of apnea; nausea and vomiting; hyperactive reflexes; and numbness of the extremities
71Metabolic Alkalosis cont’d Medical treatmentDepends on the underlying cause and severity of the condition
72Metabolic Alkalosis cont’d Nursing careAssessmentTake vital signs and daily weight; monitor heart rate, respirations, and fluid gains and lossesKeep accurate intake and output records, including the amount of fluid removed by suctionAssess motor function and sensation in the extremities; monitor laboratory values, especially pH and serum bicarbonate levels
73Metabolic Alkalosis cont’d InterventionTo prevent metabolic alkalosis, use isotonic saline solutions rather than water for irrigating nasogastric tubes because the use of water for irrigation can result in a loss of electrolytesProvide reassurance and comfort measures to promote safety and well-being