Fluid & Electrolytes

Calcium

8.4-10.5

Regulation of water imbalance

1. hypothalamic: 2. pituitary: 3. Adrenal: 4. GI: 5. Cardiac:

Magnesium

1.5-2.5

Sodium

136-145

Phosphate

2.5-4.5

Potassium

3.5-5

Identify risk factors for fluid and electrolyte imbalances

Fluid and electrolyte imbalances occur to some degree in most patients with a major illness or injury because illness disrupts the normal homeostatic mechanism. Some fluid and electrolyte imbalances are directly caused by illness or disease (e.g., burns, heart failure). At other times, therapeutic measures (e.g., IV fluid replacement, diuretics) cause or contribute to fluid and electrolyte imbalances. Perioperative patients are at risk for the development of fluid and electrolyte imbalances because of fluid restrictions, blood or fluid loss, and the stress of surgery. Imbalances are commonly classified as deficits or excesses. Although each imbalance is discussed separately in this chapter, it is common for more than one imbalance to occur in the same patient. For example, a patient with prolonged nasogastric suction will lose sodium, potassium, hydrogen, and chloride ions. These imbalances may result in a deficiency of both sodium and potassium, a fluid volume deficit, and metabolic alkalosis caused by loss of hydrochloric acid. Stressors (mental/ physical) Medications IV Fluids Trauma/physical alterations (bleeding out/ running a marathon)

what are the prevalent ions in ICF and ECF?

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. ICF: potassium & phosphate

Describe the composition of the major body fluid compartments.

Intracellular 2/3: the two fluid compartments in the body are the intracellular space (inside the cells) consists of interstitial fluid (the fluid in the spaces between cells), plasma (the liquid part of blood), and transcellular fluid (a very small amount of fluid contained within specialized cavities of the body). Transcellular fluids include cerebrospinal fluid; fluid in the gastrointestinal (GI) tract; and pleural, synovial, peritoneal, intraocular, and pericardial fluid. 40% body weight in adults. intra cellular fluid. 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. extracellular 1/3: ECF consists of one third of the body water; this would amount to about 14 L in a 70-kg man. About 20% of ECF is in the intravascular space as plasma (3 L in a 70-kg man), and 70% is in the interstitial space (10 L in a 70-kg man). The fluid in the transcellular spaces totals about 1 L at any given time. However, because 3 to 6 L of fluid is secreted into and reabsorbed from the GI tract every day, loss of this fluid. 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.

Describe the composition and indications of common IV fluid solutions

Isotonic Most common Fluid with the same osmolality as the cell interior. Normally the ECF and ICF are isotonic to each other. D5W, NS (0.9%), LR is isotonic with lytes. 0.9% sodium chloride lactated Ringer's solution 5% dextrose in water Ringer's solution Hypertonic Also known as hyperosmolality or hypersodium, has a greater concentration of sodium than plasma has. These solutions move water out of cells, which makes the cells shrink. IVF's: 3%NS, 5%NS 3% sodium chloride 5% sodium chloride 5% dextrose and 0.45% sodium chloride 5% dextrose and 0.9% sodium chloride D5LR D10W D20W D50W Hypotonic Hypo-osmolalility or hyposodium containing solutions have a lower concentration of sodium than plasma. These solutions promote movement of water into cells, making cells swell. Hypotonic IVF: 0.45%NS, 0.33% NS 0.45% sodium chloride 0.33% sodium chloride 0.2% sodium chloride 2.5% dextrose in water Osmotic pressure It is the force or pressure exerted by plasma proteins (albumin) that are contained in the intravascular and interstitial compartments. This is the "something" that pulls the fluid back into the capillary. Albumin acts like a "water magnet" to attract water inside the blood vessel.

Describe common fluid, electrolyte imbalances

Page 292 lewis (fluid imbalance) Page 295 table (lewis) (electrolyte imbalances)

Describe the etiology, laboratory diagnostic findings, clinical manifestations, and nursing and collaborative management of b. Sodium imbalances: hypernatremia and hyponatremia

Sodium (+) Maintains extracellular fluid Maintains acid-base balance Main function water balance (where NA goes water follows) Regulate sodium=regulate fluid volume Regulated by aldosterone, ADH and renal blood flow Transmit impulses to stimulate muscles Sources Processed or preserved foods Stored in kidneys Balanced by kidneys, aldosterone, ADH and peptide Assessment Cerebral changes Neuromuscular changes Intestinal changes (gastrointestinal) Cardiovascular Lab values ( 136-145 mEq/L)

Describe the processes involved in regulating fluid and electrolyte balance.

Water regulation: Hypothalamic-Pituitary Regulation: Water ingestion will equal water loss in the individual who has free access to water, a normal thirst and ADH mechanism, and normally functioning kidneys. 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 ADH release. The distal tubules and collecting ducts in the kidneys respond to ADH by becoming more permeable to water. The result is increased water reabsorption from the tubular filtrate into the blood and decreased excretion in the urine. Together these factors result in increased free water in the body and decreased plasma osmolality. Other factors that stimulate ADH release include stress, nausea, nicotine, and morphine. A decreased plasma osmolality or water excess suppresses secretion of ADH, resulting in urinary excretion of water. It is common for the postoperative patient to have a lower plasma osmolality, possibly because of the stress of surgery and opioid analgesia. Social and psychologic factors not related to fluid balance also affect the desire to consume fluids. A dry mouth will cause the patient to drink, even when there is no measurable body water deficit. Renal Regulation: 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. 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. 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. Adrenal Cortical: Glucocorticoids and mineralocorticoids secreted by the adrenal cortex help regulate both water and electrolytes. The glucocorticoids (e.g., cortisol) primarily have an antiinflammatory effect and increase serum glucose levels, whereas the mineralocorticoids (e.g., aldosterone) enhance sodium retention and potassium excretion (Fig. 17-9). When sodium is reabsorbed, water follows because of osmotic changes. Aldosterone is a mineralocorticoid with potent sodium-retaining and potassium-excreting capabilities. 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 (see Fig. 45-4). In addition to the RAAS, increased plasma potassium, decreased plasma sodium, and adrenocorticotropic hormone (ACTH) from the anterior pituitary act directly on the adrenal cortex to stimulate the secretion of aldosterone. Cardiac: Natriuretic peptides, including atrial natriuretic peptide (ANP) and b-type natriuretic peptide (BNP), are hormones produced by cardiomyocytes. They are natural antagonists to the RAAS. They are produced in response to increased atrial pressure (increased volume, such as occurs in heart failure) and high serum sodium levels. They suppress secretion of aldosterone, renin, and ADH, and the action of angiotensin II. In the renal tubules these peptides promote excretion of sodium and water, resulting in a decrease in blood volume and blood pressure. Gastrointestinal: Daily water intake and output are normally between 2000 and 3000 mL Regulation of electrolytes: Osmosis: Movement of water Low solute to high Passive no energy required Facilitated Diffusion: Selective Might need hitch a ride Example insulin to carry glucose into cell Diffusion: Movement of solute (particles) High solute to low Passive no energy required Active transport: Solutes move lower to higher concentration, (swimming against the current) Requires energy= adenosine triphosphate (ATP) During active transport energy from ATP moves solutes from lower to higher concentration areas Example: sodium/potassium pump, calcium, acids, and sugars

Describe the etiology, laboratory diagnostic findings, clinical manifestations, and nursing and collaborative management of a. Extracellular fluid volume imbalances: fluid volume deficit and fluid volume excess

lewis page 292

Output

urine, feces, sweat, vomiting, drainage, fistulas