NR324- Adult Health I- STUDY GUIDE Exam 1

Acid-Base, Fluid and Electrolytes Ch. 17~Respiratory System Ch. 26, 27, 28 & 29n Calculation of Fluid Gain or Loss One liter of water weighs 2.2 lb (1 kg). Body weight change, especially sudden change, is an excellent indicator of overall fluid volume loss or gain. For example, if a patient drinks 240 mL (8 oz) of fluid, weight gain will be 0.5 lb (0.23 kg). A patient receiving diuretic therapy who loses 4.4 lb (2 kg) in 24 hours has experienced a fluid loss of approximately 2 L. An adult patient who is fasting might lose approximately 1 to 2 lb/day. A weight loss exceeding this is likely due to loss of body fluid. Electrolyte Composition of Fluid Compartments Electrolytes are substances whose molecules dissociate, or split into ions, when placed in water. 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. Most proteins bear a negative charge and are thus anions. Electrolyte composition varies between ECF and ICF. The overall concentration of electrolytes is approximately the same in the two compartments. However, concentrations of specific ions differ greatly (Fig. 17-3). In ECF the main cation is sodium, with small amounts of potassium, calcium, and magnesium. The primary ECF anion is chloride, with small amounts of bicarbonate, sulfate, and phosphate anions. In ICF the most prevalent cation is potassium, with small amounts of magnesium and sodium. The prevalent ICF anion is phosphate, with some protein and a small amount of bicarbonate. (Normal serum electrolyte values are presented in Table 17-1.) Normal Serum Electrolyte Values Electrolyte Reference Interval Anions Bicarbonate (HCO3−) 22-26 mEq/L (22-26 mmol/L) Chloride (Cl−) 96-106 mEq/L (96-106 mmol/L) Phosphate (PO43−)* 2.4-4.4 mg/dL (0.78-1.42 mmol/L) Cations Potassium (K+) 3.5-5.0 mEq/L (3.5-5.0 mmol/L) Magnesium (Mg2+) 1.5-2.5 mEq/L (0.75-1.25 mmol/L) Sodium (Na+) 135-145 mEq/L (135-145 mmol/L) Calcium (Ca2+) (total) 8.6-10.2 mg/dL (2.15-2.55 mmol/L) Calcium (ionized) 4.6-5.3 mg/dL (1.16-1.32 mmol/L) The majority of the phosphorus (P) in the body is found as phosphate (PO43−). The terms are used interchangeably in this text. Fluid Volume Deficit • Causes: Fluid volume deficit can occur with abnormal loss of body fluids (e.g., diarrhea, fistula drainage, hemorrhage, polyuria), inadequate intake, or a shift of fluid from plasma into interstitial fluid. The term fluid volume deficit is not interchangeable with the term dehydration. Dehydration refers to loss of pure water alone without a corresponding loss of sodium. Causes and clinical manifestations of fluid volume deficit are listed in Table 17-3. • ↑ Insensible water loss or perspiration (high fever, heatstroke) • Diabetes insipidus • Osmotic diuresis • Hemorrhage • GI losses: vomiting, NG suction, diarrhea, fistula drainage • Overuse of diuretics • Inadequate fluid intake • Third-space fluid shifts: burns, intestinal obstruction • Clinical Manifestations: • Restlessness, drowsiness, lethargy, confusion • Thirst, dry mucous membranes • Decreased skin turgor, ↓ capillary refill • Postural hypotension, ↑ pulse, ↓ CVP • ↓ Urine output, concentrated urine • ↑ Respiratory rate • Weakness, dizziness • Weight loss • Seizures, coma • Collaborative care The goal of treatment for fluid volume deficit is to correct the underlying cause and to replace both water and any needed electrolytes. Balanced IV solutions, such as lactated Ringer's solution, are usually given. Isotonic (0.9%) sodium chloride is used when rapid volume replacement is indicated. Blood is administered when volume loss is due to blood loss. • Nursing Diagnoses • Deficient fluid volume related to excessive ECF losses or decreased fluid intake • Decreased cardiac output related to excessive ECF losses or decreased fluid intake • Risk for deficient fluid volume related to excessive ECF losses or decreased fluid intake • Potential complication: hypovolemic shock • Nursing Implementation Intake and output, cardiovascular, respiratory and n