ANATOMY AND PHYSIOLOGY Body fluid: As the primary body fluid, water is the most important nutrient of life. Although life can be sustained for many days without food, humans can survive for only a few days without water.
Water in the body functions primarily to: Provide a medium for transporting nutrients to cells and wastes from cells, and for transporting substances such as hormones, enzymes, blood platelets, and red and white blood cells. Facilitate cellular metabolism and proper cellular chemical functioning. Act as a solvent for electrolytes and nonelectrolytes
Help maintain normal body temperature Facilitate digestion and promote elimination Act as a tissue lubricant An insulator and shock absorber
Body Fluid Compartments Fluids are located in two main compartments, or spaces, in the body—the intracellular fluid (ICF) and extracellular fluid (ECF). ICF is the fluid within cells, constituting about 40% of an adult’s body weight, or 70% of the total-body water.
ECF is all the fluid outside the cells. It constitutes about 20% of an adult’s body weight, or 30% of total-body water. ECF includes* intravascular and *interstitial fluids. Intravascular fluid, or plasma, is the liquid component of the blood (ie, fluid found within the vascular system). Interstitial fluid is the fluid that surrounds tissue cells and includes lymph. *Transcellular fluids: CSF, Peritoneal, pericardial, pleural, pancreatic, intraocular, biliary, & synovial fluids.
(B) Body fluid distribution on the microscopic level.
The term total-body water or fluid refers to the total amount of water in the body expressed as a percentage of body weight. Variations in Fluid Content In a healthy person, total-body water constitutes about 50% to 60% of the body’s weight, depending on such factors as the person’s age, lean body mass, and sex.
Composition of Body Fluids ECF and ICF contain oxygen from the lungs, dissolved nutrients from the gastrointestinal tract, excretory products of metabolism such as carbon dioxide, and charged particles called ions. An ion is an atom or molecule carrying an electrical charge. Substances capable of breaking into electrically charged ions when dissolved in a solution are called electrolytes. Some ions develop a positive charge and are called cations. Others develop a negative charge and are called anions. These charges are the basis of chemical interactions in the body necessary for metabolism and other functions.
Electrolytes are measured in milliequivalent per liter of water (mEq/L) or milligrams per 100 milliliters (mg/100mL).The term milliequivalent refers to the chemical combining power of the ion. The is the unit of measure that describes the chemical activity of electrolytes. One milliequivalent of either a cation or an anion is chemically equivalent to the activity of 1 mg of hydrogen ion. Therefore, 1 mEq of any cation is equivalent to 1 mEq of any anion.
Movement of body Fluids and Electrolytes The body fluid compartments are separated from one another by cell membranes and the capillary membrane.” Selectively permeable”. Small particles such as ions, oxygen, and carbon dioxide easily move across these membranes, but larger molecules like glucose and protein have more difficulty moving between fluid compartments. The methods by which electrolytes and other solutes move are:-
1- Osmosis is the movement of water across cell membranes, from the less concentrated solution to the more concentrated solutions. Solutes are substances that are dissolved in a liquid. Solutes may be crystalloids ( salts that dissolve readily into true solutions) or colloids (substances such as large protein molecules that do not readily dissolve into true solutions). Solvent is the component of a solution that can dissolve a solute. Water is the primary solvent in the body. The solutes are electrolytes, oxygen and carbon dioxide, glucose, urea, amino acids, and proteins.
Osmolality: concentration of solutes in body fluids (mOsm / kg). An isotonic solution has the same osmolality as body fluids. Normal saline, 0.9% sodium chloride, is an isotonic solution. Hypertonic solutions have a higher osmolality than body fluids, 3% sodium chloride is a hypertonic solutions. Hypotonic solutions have a lower osmolality than body fluids, 0.45% sodium chloride (one half normal saline) is a hypotonic solutions.
Osmotic pressure is the power of a solution to draw water across a semi permeable membrane. Because a hypertonic solution has a greater osmolality, water moves out of the cells and is drawn into the intravascular compartment, causing the cells to shrink. Due to a lower osmolality, a hypotonic solution in the intravascular space moves out of the intravascular space and into intracellular fluid, causing cells to swell and possibly burst.
In the body, Plasma proteins (high molecular weights) exert an osmotic draw called Colloid osmotic pressure or Oncotic pressure, pulling water from the interstitial space into the vascular compartment.
2- Diffusion The solute moves from an area of higher concentration to an area of lower concentration until equilibrium is established. Gases also move by diffusion. Oxygen and carbon dioxide exchange in the lung’s alveoli and capillaries occurs by diffusion.
3- Filtration is a process whereby fluid and solutes move together across a membrane from one compartment to another. Passage is from an area of high pressure to one of lower pressure. An example of filtration is the movement of fluid and nutrients from the capillaries of the arterioles to the interstitial fluid around the cells.
Hydrostatic pressure is the pressure exerted by a fluid within a closed system on the walls of a container in which it is contained. The hydrostatic pressure of blood is the force exerted by blood against the vascular walls.
Filtration pressure is the difference between colloid osmotic pressure and blood hydrostatic pressure. These pressures are important in understanding how fluid leaves arterioles, enters the interstitial compartment, and eventually returns to the venules. The filtration pressure is positive in the arterioles, helping to force or filter fluids into interstitial spaces; it is negative in the venules and thus helps fluid enter the venules.
4- Active Transport Is a process that requires energy for the movement of substances through a cell membrane from an area of lesser solute concentration to an area of higher solute concentration. Active transport can be called “pumping uphill.” Substances believed to use active transport include amino acids, glucose (in certain places only, such as in the kidneys and intestines), and ions of sodium, chloride, potassium, hydrogen, phosphate, calcium, and magnesium.
Regulating body fluids The desirable amount of fluid intake and loss in adults ranges from 1500 to 3500 mL each 24 hours, with most people averaging 2500 mL per day. A person’s intake should normally be approximately balanced by output or fluid loss. A general rule is that in healthy adults, the output of urine normally approximates the ingestion of liquids, and the water from food and oxidation is balanced by the water loss through the feces, the skin, and the respiratory process. The intake–output balance may not always occur in a single 24-hour period but should normally be achieved within 2 to 3 days.
Fluid Sources Water for the body derives from several sources, including ingested liquids, food, and metabolism. Ingested Liquids The ingestion of liquids makes up the largest amount of water normally taken into the body. Fluid intake is primarily regulated by the thirst mechanism. Located within the hypothalamus, the thirst control center is stimulated by intracellular dehydration and decreased blood volume.
Water in Food The water contained in food is the second largest source of water for the body. The amount ingested depends on the diet. For example, melons and citrus fruit are high in water content, whereas cereal and dried fruits have a relatively low water content. Water From Metabolic Oxidation Water is an end product of the oxidation that occurs during the metabolism of food substances, specifically, carbohydrates, fats, and protein. This source also varies among different types of nutrients.
Fluid Losses Water is lost from the body through the kidneys as urine, through the intestinal tract in feces, and through the skin as perspiration. These losses are termed sensible water losses. Insensible water loss, that which is imperceptible also occurs. For example, an invisible amount of water is lost from the skin constantly through evaporation. Insensible loss from the lungs is moisture exhaled in breaths. Any deviations from normal ranges for a balanced water intake and output should alert the nurse to potential imbalances.
Maintaining Homeostasis Fluid homeostasis normally functions automatically and effectively. Almost every organ and system in the body helps in some way to maintain fluid homeostasis. Fluid balance is threatened when any organ fails to function properly. The kidneys, frequently referred to as the master chemists of the body, normally filter 135 to 180 L of plasma daily in the adult, while excreting only 1.5 L of urine; selectively retain electrolytes and water and excrete wastes and excesses.
Antidiuretic Hormone It regulates water excretion from the kidney, is synthesized in the anterior portion of the hypothalamus and acts on the collecting ducts of the nephrons. When serum Osmolality rises, ADH is produced, causing the collecting ducts to become more permeable to water. This increased permeability allows more water to be reabsorbed into the blood. As more water is reabsorbed, urine output falls and serum osmolality decreases because the water dilutes body fluid. If serum Osmolality decreases, ADH is suppressed, the collecting ducts become less permeable to water and urine output increases.
Other factors also affect the production and release of ADH, including blood volume, temperature, pain, stress, and some drugs such as opiates, barbiturates, and nicotine.
Renin- angiotension- Aldestrone system Receptors found in the justaglomerular cells of the kidney nephrons. If blood flow or pressure to the kidney ↓→renin released →convert angiotensinogen to angiotension 1 →angiotension 2 by angiotension – converting enzyme. Angiotension 2 acts directly on the nephrons to promote sodium and water retention also stimulates the release of aldosterone from the adrenal cortex. The net effect of the renin-angiotension- aldosterone system is to restore blood volume (and renal perfusion) through sodium and water retention.
Atrial Natriuretic factor ANF is released from cells in the atrium of the heart in response to excess blood volume and stretching of the atrial walls. Acting on the nephrons, ANF promotes sodium wasting and acts as a potent diuretic, thus reducing vascular volume.ANF also inhibits thirst, reducing fluid intake.
Regulating electrolytes Electrolytes are important for: Maintaining fluid balance Contributing to acid-base regulation Facilitating enzyme reactions Transmitting neuromuscular reactions.
Most electrolytes enter the body through dietary intake and are excreted in the urine. Some electrolytes, such as sodium and chloride, are not stored by the body and must be consumed daily to maintain normal levels. Potassium and calcium, on the other hand, are stored in the cells and bones, when serum levels drop, ions can shift out of the storage into the blood to maintain adequate serum levels for normal functioning.
Sodium (Na+) - ECF. - Major contributor to serum osmolality. - Sodium functions in controlling and regulating water balance. - Aldestrone increases Na+ reabsorption in collecting duct of nephrons. Function: Regulating ECF volume and distribution Maintaining blood volume Transmitting nerve impulses and contracting muscles.
Potassium (K+) –ICF –Vital electrolyte for skeletal, cardiac, and smooth muscle activity. –Maintaining acid-base balance –Contributor of intracellular enzyme reactions. –Aldestrone increases K+ excretion –Insulin helps move K+ into cells tissues damage and acidosis shift K+ out of cells into ECF.
Function: Maintaining ICF osmolality. Transmitting nerve and other electrical impulses. Regulating cardiac impulses transmission Skeletal and smooth muscle function Regulating acid-base balance
Calcium (Ca2+) - Is found in the skeletal system. - Small amount in Extracellular fluids. - Regulating muscle contraction and relaxation, neuromuscular function, and cardiac function -ECF calcium is regulated by complex interaction of parathyroid hormone, calcitriol, calcitonin and metabolite of vitamin D. - When calcium levels in the ECF fall, parathyroid hormone and calcitriol, causes calcium to be released from the bone into ECF and increase absorption of calcium in the intestine.
Function: Forming bones and teeth Transmitting nerve impulses Regulating muscle contractions Maintaining cardiac pacemaker Blood clotting Activating enzymes such as pancreatic lipase and phospholipase.
Bicarbonate (HCO3-): Bicarbonate (HCO3-) an anion that is the major chemical base buffer within the body; found in both ECF and ICF. Function Is essential for acid–base balance; bicarbonate and carbonic acid constitute the body’s primary buffer system.
Acid–Base Balance Body fluids must maintain an acid–base balance to sustain health and life. Acidity or alkalinity of a solution is determined by its concentration of hydrogen ions (H+). An acid is a substance containing hydrogen ions that can be liberated or released. An alkali, or base, is a substance that can accept or trap hydrogen ions.
An acid releases hydrogen, as follows: A base traps hydrogen, as follows:
The unit of measure used to describe acid–base balance is pH, which is an expression of hydrogen ion concentration and the resulting acidity or alkalinity of a substance. Normal blood plasma is slightly alkaline and has a normal pH range of 7.35 to 7.45.
The narrow range of normal pH is achieved through three major homeostatic regulators of hydrogen ions: 1)Buffer systems. 2)Respiratory mechanisms. 3)Renal mechanisms.
Buffer Systems A buffers prevent excessive changes in PH by removing or releasing hydrogen ions. If excess hydrogen ion is present in body fluids, buffers bind with the hydrogen ion, minimizing the change in pH. When body fluids become too alkaline, buffers can release hydrogen ion, minimize the change in pH. The major buffer system in ECF is the bicarbonate (HCO3-) and carbonic acid (H2co3).
An acid releases hydrogen, as follows: A base traps hydrogen, as follows:
When a strong acid such as hydrochloric acid (HCL) is added, it combines with bicarbonate and the pH drops only slightly. A strong base such as sodium hydroxide combines with carbonic acid, the weak of the buffer pair, and the pH remains within the narrow range of normal. The amounts of bicarbonate and carbonic acid in the body vary, however, as long as a ratio of 20 parts of bicarbonate to 1 part of carbonic acid is maintained, the pH remains within its normal range of 7.35 – 7.45.
Respiratory Regulation The lungs help regulate acid – base balance by eliminating or retaining CO2, a potential acid. Combined with water, CO2 forms. This chemical reaction is reversible, H2CO3 breaks down into CO2 and H2O. CO2 is powerful stimulator of the respiratory center. When blood levels of H2CO3 and CO2 rise, the respiratory center is stimulated and the rate and depth of respirations increase. CO2 is exhaled, and H2CO3 levels fall.
By contrast, when HCO3 levels are excessive, the rate and depth of respirations are reduced. This causes CO2 to be retained, H2CO3 levels to rise, and the excess HCO3 to be neutralized. PaCo2 is 35 – 45 mmHg.
Renal regulation The kidneys maintain acid – base balance by selectively excreting or conserving bicarbonate and hydrogen ions. When excess hydrogen ion is present and the pH falls, the kidneys reabsorb and regenerate bicarbonate and excrete hydrogen ion. In the case of alkalosis and a high pH, excess bicarbonate is excreted and hydrogen ion is retained. Normal HCO3 level is 22 to 26mEq/L.
Acidosis & Alkalosis Acidosis is the condition characterized by an excess of hydrogen ions in ECF in which the pH falls below Alkalosis occurs when there is a lack of hydrogen ions and the pH exceeds 7.45.
Factors Affecting Body Fluid, Electrolyte, and Acid –Base Balance: Age Infants and growing children have much greater fluid turnover than adults because their higher metabolic rate increases fluid losses. Infants lose more fluid though the kidneys because immature kidneys, infants respirations are more rapid and the body surface area is proportionately greater than that of adults.
In elderly people, the thirst response often is blunted. Antidiuritic hormone level remains normal or may even be elevated, but the nephrons become less able to conserve water in response to ADH. Also when combined with the increased likelihood of heart diseases impaired renal function, and multiple drug regimens, more fragile skin and veins, which can make an intravenous insertion more difficult.
Gender and body size Fat cells contain little or no water & lean tissue has high water content. People with a higher percentage of body fat have less body fluid. Women have proportionately more body fat & less body water than men. In obese individual this may be even less, with water responsible for only 30%-40% of the person’s weight.
Environmental Temperature People with an illness and those participating in strenuous activity are at risk for fluid and electrolyte imbalances when the environmental temperature is high. Both salt and water are lost through sweating. When only water is replaced, salt depletion is a risk, may experience fatigue, weakness, headache, and gastrointestinal symptoms such as anorexia and nausea, at risk for heat exhaustion, or heatstroke.
Lifestyle Other factors such as diet, exercise, and stress affect fluid, electrolyte, and acid-base balance. Diet: people with anorexia nervosa or bulimia are at risk for severe fluid and electrolyte imbalances because of inadequate intake or purging regimens. Seriously malnourished people develop edema because the osmotic draw of fluid into the vascular compartment is reduced.
Exercise: regular weight-bearing physical exercise such as walking, running effect on calcium balance. The rate of bone loss that occurs in postmenopausal women and older men is slowed with regular exercise, reducing the risk of osteoporosis. Stress: it increases cellular metabolism, blood glucose concentration, and catecholamine levels. Stress can increase production of ADH, which in turn decreases urine production. Heavy alcohol consumption, increasing the risk of low calcium, magnesium, and phosphate levels.
DISTURBANCES IN FLUID, ELECTROLYTE, & ACID–BASE BALANCE
Fluid Imbalances Fluid imbalances are of two basic types: isotonic and osmolar. Isotonic imbalances occur when water and electrolytes are lost or gained in equal proportions, so that the Osmolarity of body fluids remain constant.
Osmolar imbalances involve the loss or gain of only water, so that the Osmolarity of the serum is altered. Categories of fluid imbalances: a)An isotonic loss of water and electrolytes. “ Fluid volume deficit” b)An isotonic gain of water and electrolytes. “ fluid volume excess” c)Hyperosmolar loss of only water. “ dehydration” d)Hypoosmolar gain of only water. “Overhydration”
Fluid Volume Deficit Isotonic fluid volume deficit (FVD) occurs when the body loses both water and electrolytes from the ECF in similar proportions. In FVD, fluid is initially lost from the intravascular compartment, so it often is called hypovolemia. FVD occurs as a result of : abnormal losses through the skin, GI, or kidney. ↓ intake of fluid, bleeding, or movement of fluid into a third space. Table
Third-space fluid shift OR Third-spacing Fluid shifts from the vascular space into an area where it is not readily accessible as extracellular fluid. This fluid remains in the body but is essentially unavailable for use, causing an isotonic fluid volume deficit. Fluid may be sequestered in the pleural, peritoneal, pericardial, or joint cavities; the bowel; or the interstitial space (plasma-to- interstitial shift). The client with third space syndrome has an isotonic fluid deficit but may not manifest apparent fluid loss or weight loss. The fluid has not been lost but is trapped in another body space for a period of time and is essentially unavailable for use.
A third-space shift may occur as a result of a severe burn, a bowel obstruction, or pancreatitis.
Fluid Volume Excess Occurs when the body retains both water and sodium in similar proportions to normal ECF. It is also called hypervolemia.
Common causes include:- - Excessive intake of sodium chloride - Administering sodium-containing infusions too rapidly -Disease processes that alter regulatory mechanisms such as heart failure, renal failure. Table
Edema Excess interstitial fluid. Edema typically is most apparent in areas where the tissue pressure is low, such as around the eyes, and in dependent tissues (known as dependent edema), where hydrostatic capillary pressure is high. Pitting edema: edema that leaves a small depression or pit after finger pressure is applied to the swollen area.
-Dehydration Or hyperosmolar imbalance. -Over hydration Or hypo-osmolar imbalance
RISK FACTOR Loss of sodium, as in: Loss of GI.fluids Use of diuretics Gains of water, as in: Excessive administration of D5W Water intoxication Disease states associated with SIADH (a form of hyponatremia) Pharmacologic agents that may impair water excretion Assessments Anorexia Nausea and vomiting Lethargy Confusion Muscle cramps Fingerprinting over sternum Muscular twitching Seizures Coma Serum Na below 135 mEq/L Urine specific gravity <1.010 Nursing interventions -Monitor fluid losses and gains. -Monitor for presence of GI and CNS symptoms. - Monitor serum Na levels. - Check urine specific gravity. -If able to eat, encourage foods and fluids with high sodium content. -Be aware of sodium content of common -IV fluids. -Avoid giving large water supplements to -Patients receiving isotonic tube feedings. -Take seizure precautions when hyponatremia is severe Hyponatremia
RISK FACTOR Water deprivation Increased sensible and insensible water loss Ingestion of large amount of salt Excessive parenteral administration of sodium- containing solutions Profuse sweating Diabetes insipidus Assessments Thirst Elevated body temperature Tongue dry and swollen, sticky mucous Membranes Severe hypernatremia Disorientation Hallucinations Irritable and hyperactive Focal or grand mal seizures Coma Serum Na above 145 mEq/L Urine specific gravity >1.015 Nursing interventions - Monitor fluid losses and gains. - Observe for excessive intake of high sodium foods. - Monitor for changes in behavior such as restlessness, lethargy, and disorientation. - Look for excessive thirst and elevated body temperature. - Monitor serum Na levels. - Check urine specific gravity. - Give sufficient water with tube feedings to Keep serum Na and BUN at normal limits. Hypernatremia
RISK FACTOR Diarrhea Vomiting or gastric suction Potassium-wasting diuretics Poor intake as in anorexia nervosa, alcoholism, potassium- free parenteral.fluids Polyuria Assessments Fatigue Anorexia, nausea, and vomiting Muscle weakness Decreased bowel motility Cardiac arrhythmias Polyuria, nocturia, dilute urine Postural hypotension Serum K below 3.5 mEq/L ECG changes T waves flattening and ST segment depression on ECG Nursing interventions - Monitor for occurrence of Hypokalemia. - Prevent Hypokalemia by: - Encouraging extra K intake if possible - Educating about abuse of laxatives and diuretics -Administer oral K supplements if ordered. - Be knowledgeable about danger of IV potassium administration. Hypokalemia
RISK FACTOR Decreased potassium excretion: Oliguric renal failure Potassium-sparing diuretics High potassium intake, especially in presence of renal insufficiency Shift of potassium out of cells into the plasma (acidosis, tissue trauma, infection, burns) Assessments Vague muscle weakness Cardiac arrhythmias Paresthesias of face, tongue, feet, and hands Flaccid muscle paralysis GI symptoms such as nausea, intermittent intestinal colic, or diarrhea may occur Serum K above 5.0 mEq/L Peaked T waves, widened QRS on ECG Nursing interventions Monitor for hyperkalemia, which is life threatening. Prevent hyperkalemia by: Following rules for safe administration of K Avoiding giving patients with renal insufficiency K-saving diuretics, K supplements, or salt substitutes Cautioning about foods high in potassium content Hyperkalemia
RISK FACTOR Surgical hypoparathyroidism Malabsorption Vitamin D deficiency Acute pancreatitis Excessive administration of citrated blood Alkalotic states Assessments Trousseau’s and Chvostek’s signs Numbness and tingling of fingers and toes Mental changes Seizures Spasm of laryngeal muscles ECG changes Cramps in muscles of extremities Total serum calcium <8.5 mg/dL Nursing interventions Take seizure precautions when hypocalemia is severe. Monitor condition of airway. Take safety precautions if confusion is present. Educate people at risk for osteoporosis about need for dietary calcium intake. Discuss calcium-losing aspects of nicotine and alcohol use. Hypocalcaemia
A positive Trousseau's sign Muscular contraction including flexion of the wrist and metacarpophalangeal joints, hyperextension of the fingers and flexion of the thumb on the palm
A positive Chvostek's sign. Twitching or contraction of the facial muscles produced by tapping on the facial nerve at specific point
RISK FACTOR Hyperparathyroidism Malignant neoplastic disease Prolonged immobilization Large doses of vitamin D Overuse of calcium supplements Thiazide diuretics Assessments Muscular weakness Tiredness, lethargy, Constipation Anorexia, nausea, and vomiting Decreased memory and attention span Polyuria and polydipsia Renal stones Cardiac arrest Serum calcium >10.5 mg/dL Nursing interventions Increase mobilization when feasible. Encourage sufficient oral intake. Discourage excessive consumption of milk products. Encourage bulk in the diet. Take safety precautions if confusion is present Be alert for signs of digitalis toxicity in Hypercalcaemia patients. Force fluids to prevent formation of renal stones. Hypercalcaemia
Acid-Base Imbalances The Arterial blood gases (ABGs) are laboratory tests commonly used in the assessment and treatment of acid–base imbalances. Acid–base imbalances occur when the carbonic acid or bicarbonate levels become disproportionate. When there is a single primary cause, these disturbances are known as respiratory acidosis or alkalosis and metabolic acidosis or alkalosis.
These disturbances are result of an upset in acid–base balance, as follows: A respiratory disturbance alters the carbonic acid portion: Respiratory acidosis and alkalosis are the results of respiratory disturbances. Compensation for a respiratory disturbance occurs when kidneys attempt to restore balance by either conserving or excreting more bicarbonate.
A metabolic disturbance alters the bicarbonate portion: Metabolic acidosis and alkalosis are almost entirely the result of metabolic processes. The primary organs for compensation with a metabolic disorder are the lungs, which either try to conserve or excrete more carbon dioxide (available in weakly ionized carbonic acid). Although compensation is the body’s natural attempt to restore balance, correction may also be required. Correction involves using nursing and medical interventions to promote a return to homeostasis (e.g, pharmacologic agents or mechanical ventilation).
Respiratory Acidosis Respiratory acidosis is a primary excess of carbonic acid in ECF. Any decrease in alveolar ventilation that results in retention of carbon dioxide can cause respiratory acidosis. As the carbonic acid content increases, the kidneys attempt to retain more bicarbonate and increase their hydrogen excretion. Thus: Respiratory acidosis = high PaCO2 because of alveolar hypoventilation
Risk factors: Acute lung conditions that impair alveolar gas exchange such as aspiration. Chronic lung diseases such as asthma. Overdose of narcotics or sedatives that depress respiratory rate and depth. Brain injury that affects the respiratory center.
Clinical Manifestation: -Tachycardia, tachypnea, headache, dizziness, convulsions. LOC. - Laboratory findings: pH = > 7.35 PaCO2 = above 45 mmHg HCO3 = normal or slightly elevated in acute; above 26 mEq/L in chronic.
Nursing Interventions: Frequently assess respiratory status and lung sounds Monitor airway and ventilation; insert mechanical ventilation as necessary. Administer pulmonary therapy measures such as inhalation therapy, percussion and postural drainage. Monitor fluid intake and output, vital signs, ABG. Administer narcotic antagonists as indicated Maintain adequate hydration (2-3L of fluid per day).
Respiratory Alkalosis Respiratory alkalosis is a primary deficit of carbonic acid in ECF. It is the result of increased alveolar ventilation and the consequent decrease in carbon dioxide. An increase in respiratory rate and depth causes the carbon dioxide loss because the carbon dioxide is excreted faster than normal. Because of the deficit of carbon dioxide, which is a respiratory stimulant sensed in the medulla of the brain, depression or cessation of respirations eventually can occur. Respiratory alkalosis = low PaCO2 because of alveolar hyperventilation
Risk factors: Extreme anxiety Elevated body temperature Overventilation with a mechanical ventilator Hypoxia Salicylate overdose.
Clinical Manifestations: Shortness of breath, chest tightness, paresthesia and numbness and tingling, tremulousness, blurred vision. Laboratory findings: pH = above 7.45 PaCO2 = less than 35mm/Hg
Nursing Interventions: Monitor vital signs and ABG Assist client to breathe more slowly Help client breathe in a paper bag or apply rebreather mask (to inhale CO2).
Metabolic Acidosis Deficit of bicarbonate in ECF. The deficit can occur as the result of an increase in acid components or an excessive loss of bicarbonate. Risk Factors: Conditions that increase nonvolatile acids in the blood ( renal impairment, DM, starvation) Conditions that decrease bicarbonate ( prolonged diarrhea) Excessive infusion of chloride-containing IV fluids (NaCl).
Clinical Manifestations: Kussmaul’s respiration (deep, rapid respiration) Lethargy, confusion, headache, nausea, vomiting. Laboratory findings: pH = below 7.35 HCO3 = less than 22mEq/L Nursing Interventions: Monitor ABG values, I&O, and LOC Administer IV sodium bicarbonate carefully if ordered Treat underlying problems as ordered.
Metabolic Alkalosis Metabolic alkalosis is a primary excess of bicarbonate in ECF. This may be the result of excessive acid losses or increased base ingestion or retention. Risk Factors: Excessive acids losses due to Vomiting Gastric suction Excessive use of potassium- losing diuretics Excessive adrenal corticoid hormones due to Cushing’s syndrome, hyperaldosteroneism. Excessive bicarbonate intake from antacids.
Clinical Manifestations: Decreased respiratory rate and depth, dizziness, tingling in extremities Hypertonic muscles, tetany Laboratory findings: pH = above 7.45 HCO3 = greater than 26 mEq/L
Nursing Interventions: Monitor I&O closely Monitor VS, especially respirations and LOC Administer ordered IV fluids carefully Treat underlying problems.
THE NURSING PROCESS FOR FLUID, ELECTROLYTE, AND ACID– BASE BALANCE
Assessing The nursing assessment is directed toward the following: Identifying patients at high risk for fluid, electrolyte, and acid–base imbalance Determining that a specific imbalance is present and identifying the nature of the imbalance along with its severity, etiology, and defining characteristics Determining the effectiveness of the plan of care
Important assessment parameters include:- –The nursing history and physical assessment –A record of fluid intake and output –Daily weights and laboratory studies.
1) – Nursing History - Identifying clients who are at risk for fluid and electrolyte, and acid –base imbalances - The current and past medical history reveals conditions such as chronic lung diseases or DM that can disrupt normal balance. - Medications and treatments - Food and fluid intake - Fluid output - Fluid and electrolyte, acid-bas imbalances
B – Physical Assessment Nurse pay attention to certain parameters when assessing a patient’s fluid and electrolyte status: Comparison of total intake and output of fluids Urine volume and concentration Skin and tongue turgor Degree of moisture in oral cavity Body weight Thirst Tearing and salivation Appearance and temperature of skin
Facial appearance Edema Vital signs Neck and hand vein filling Results of hemodynamic monitoring (e.g., central venous pressure [CVP]) Neuromuscular irritability
C – Clinical Measurements: 1- Daily weight - Significant changes in weight over a short time are indicative of acute fluid changes. Each ilogram of weight gained or lost is equivalent to 1 L of fluid gained or lost To obtain accurate weight measurements, the nurse should balance the scale before each use and weight the client (a) at the same time each day (before breakfast after first void). (b) Wearing the same or similar clothing, and (c) on the same scale.
- Measuring I&O may be impractical because of lifestyle or problems with incontinence - Blood pressure, a sensitive measure to detect blood volume changes, may fall significantly with FVD and hypovolemia or increase with FVE. - Tachycardia – hypovolemia. - Irregular pulse rate – electrolyte imbalance. - Respiratory rate – acid base.
2- Fluid Intake and Output During a 24 hours period provides important data about the client’s fluid and electrolyte balance 3- Laboratory Tests Many laboratories studies are conducted to determine the client’s fluid and electrolyte, and acid- base status. Serum Electrolytes Serums electrolytes also are routinely are assessed for clients at risk in the community, or who are being treated with a diuretic for hypertension or heart failure.
Complete Blood Count (CBC) The HCT measures the volume of blood that is composed of RBCs. Because the HCT is a measure of the volume of cells in relation to plasma. Thus the HCT increases with severe dehydration and decreases with severe overhydration. Normal HCT value is % (men) 37-47% (women). Osmolarity Serum Osmolarity is a measure of the solute concentration of the blood. Normal values are275– 295 mOsm/kg. An increase in serum Osmolarity indicates a fluid volume deficit; a decrease in serum Osmolarity indicates fluid volume excess.
Urine Osmolarity Is a measure of the solute concentration of urine. Normal values are mOsm/kg. Increased urine Osmolarity indicates a fluid volume deficit, decreased urine Osmolarity reflects a fluid volume excess Urine pH By using a dipstick on a freshly voided specimen. Normally the pH of the urine is relatively acidic, averaging about 6.0, but a range of 4.5–8.2 is considered normal.
Urine Specific Gravity Is an indicator of urine concentration that can be performed quickly and easily by nursing personnel Normal specific gravity range from (concentrated urine: 1.02–1.030 or more; dilute urine: 1.001–1.010).
Arterial blood Gases Arterial blood gases are obtained to determine the adequacy of oxygenation and ventilation and to assess acid–base status. When interpreting ABGs, follow these necessary steps: 1. Determine whether the pH is Alkalotic or Acidotic. 2. Check for the cause of the change in pH. Is it respiratory (PaCO2) or metabolic (HCO3–)? In respiratory acid–base imbalances, the pH and PaCO2 values are inversely abnormal (move in opposite directions):
metabolic acid–base imbalances, the pH and HCO3 values are either high or both low:
3. Determine whether the body is compensating for the PHchange. When the problem is respiratory, the renal system attempts to compensate either by increasing or by decreasing HCO3–. In contrast, the respiratory system compensates for a metabolic acid–base imbalance by regulating CO2 levels. When compensation occurs, the PaCO2 and the HCO3– will always point in the same direction. The focus of compensation efforts is to return the pH to the normal range:
4. Look at the total picture and determine whether compensation has occurred. Compensation is classified as Follows: Absent if: PH abnormal One component abnormal Second component within normal range Partial if: PH abnormal One component abnormal Second component beginning to change Complete if: PH within normal range One component abnormal Second changed to move pH within normal range
Implementing Promoting Wellness They know it is important to drink adequate fluids and consume a balance diet. Nurses can promote client’s health by providing wellness teaching that will help them maintain fluid and electrolyte balance. Enteral Fluid and Electrolyte Replacement Fluids and electrolytes can be provided orally in the home and hospital if the client health permits, and if he has intact GIT and gag and swallow reflexes. Clients who are unable to ingest solid foods may be able to ingest fluids.
Fluid Intake Modification Restricted fluids may be necessary for clients who have fluid retention (FVE) as a result of renal failure, CHF, SIADH, or other disease processes. Fluid restrictions vary from NPO to a precise amount ordered by a physician. Dietary Changes Specific fluid and electrolytes imbalances may require simple dietary changes. Some clients with fluid retention need to avoid foods high in sodium. Most healthy clients can benefit from food rich in calcium.
Oral Electrolyte supplements Some clients can benefit from oral supplement of electrolyte, when dietary intake is inadequate for a specific electrolyte, or when fluid and electrolyte losses are excessive as a result of e.g. Excessive perspiration. Corticosteroids and many diuretics can cause too much potassium to be eliminated through the kidney. People who ingest insufficient milk and milk products benefit from calcium supplements. Although routine supplements for other electrolytes generally are not recommended, clients who have poor dietary habits, who are malnourished, or who have difficulty accessing or eating fresh fruits and vegetables may benefit from electrolyte supplements.
Parental Fluid and Electrolyte Replacement IV fluid therapy is essential when clients are unable to take food and fruits orally. IV fluids therapy is usually ordered by the physician. The nurse is responsible for administering and maintaining the therapy and for the teaching the client and significant others how to continue the therapy at home.
Volume Expanders Are used to increase the blood volume following severe loss of blood such as from hemorrhage or loss of plasma from severe burns, which draw large amounts of plasma from the blood stream to the burn site. Example :- dextran, plasma, albumin.
Supplies about 170 cal/L and contains 50 g of glucose Should not be used in excessive volumes because it does not contain any sodium; Not desirable as routine maintenance solution because it provides only Na+ and Cl. which are provided in excessive amounts. Used to treat diabetic Ketoacidosis. A roughly isotonic solution that contains multiple electrolytes in about the same concentrations as found in plasma (note that this solution is lacking in Mg and PO4) Used in the treatment of hypovolemia, burns, and fluid lost as bile or diarrhea Useful in treating mild metabolic acidosis Isotonic Solutions 5% dextrose in water (D5W) 0.9% NaCl (normal saline) Lactated Ringer’s solution
A hypotonic solution that provides Na+, Cl., and free water Na+ and Cl- allows kidneys to select and retain needed amounts Free water desirable as aid to kidneys in elimination of solutes A hypotonic solution that provides Na+, Cl. and free water Often used to treat hypernatremia (because this solution contains a small amount of Na+, it dilutes the plasma sodium while not allowing it to drop too rapidly) Hypotonic Solutions 0.33% NaCl (1/3-strength saline) 0.45% NaCl (1/2-strength saline)
A common hypertonic solution used to treat hypovolemia; used to maintain fluid Intake. Supplies 340 cal/L Used for peripheral parenteral nutrition (PPN) Replaces nutrients electrolytes Can temporarily be used to treat hypovolemia if plasma expander is not available Hypertonic Solutions 5% dextrose in 0.45% NaCl 10% dextrose in water (D10W) 5% dextrose in 0.9% NaCl (normal saline)