week 2 Flashcards
Hydrostatic Pressure
Force within a fluid compartment
Major force that pushes water out of vascular system at capillary level
Oncotic Pressure
Osmotic pressure exerted by colloids in solution
Protein is a major colloid.
Fluid Shifts AND EDEMA
Plasma-to-interstitial fluid shift results in edema.
Elevation of hydrostatic pressure
Decrease in plasma oncotic pressure
Elevation of interstitial oncotic pressure
Effects of Edema (cont’d.)
-Functional impairment:
Restricts range of joint movement
Reduced vital capacity
Impaired diastole
-Pain:
Edema exerts pressure on nerves locally.
Headache with cerebral edema
Stretching of capsule in organs (kidney, liver)
-Dental practice:
Difficult to take accurate impressions
Dentures do not fit well
-Edema in skin:
Susceptible to tissue breakdown from pressure
Impaired arterial circulation
Ischemia leading to tissue breakdown
Fluid Movement Between ECF and ICF
-Water deficit (increased ECF)
Associated with symptoms that result from cell shrinkage as water is pulled into vascular system
-Water excess (decreased ECF)
Develops from gain or retention of excess water
Fluid Spacing
First spacing
Normal distribution of fluid in ICF and ECF
Second spacing
Abnormal accumulation of interstitial fluid (edema)
Third spacing
Fluid accumulation in part of body where it is not easily exchanged with ECF
Hypothalamic Regulation
- Osmoreceptors in hypothalamus sense fluid deficit or increase.
- -Stimulates thirst and antidiuretic hormone (ADH) release
- -Result in increased free water and decreased plasma osmolarity
Pituitary Regulation
Under control of hypothalamus, posterior pituitary releases ADH.
Stress, nausea, nicotine, and morphine also stimulate ADH release.
Adrenal Cortical Regulation
Releases hormones to regulate water and electrolytes
Glucocorticoids: Cortisol
Mineralocorticoids: Aldosterone
Renal Regulation
Primary organs for regulating fluid and electrolyte balance
-Adjusting urine volume: Selective reabsorption of water and electrolytes. Renal tubules are sites of action of ADH and aldosterone.
Cardiac Regulation
Natriuretic peptides are antagonists to the RAAS.
- -Produced by cardiomyocytes in response to increased atrial pressure
- -Suppress secretion of aldosterone, renin, and ADH to decrease blood volume and pressure
Gastrointestinal Regulation
Oral intake accounts for most water.
Small amounts of water are eliminated by gastrointestinal tract in feces.
Diarrhea and vomiting can lead to significant fluid and electrolyte loss.
Insensible Water Loss
Invisible vaporization from lungs and skin to regulate body temperature
- -Approximately 600 to 900 mL/day is lost.
- -No electrolytes are lost.
Age-Related Considerations
Structural changes in kidneys decrease ability to conserve water.
Hormonal changes lead to decrease in ADH and ANP.
Loss of subcutaneous tissue leads to increased loss of moisture.
Reduced thirst mechanism results in decreased fluid intake.
Nurse must assess for these changes and implement treatment accordingly.
Age-Related Considerations
Structural changes in kidneys decrease ability to conserve water.
Hormonal changes lead to decrease in ADH and ANP.
Loss of subcutaneous tissue leads to increased loss of moisture.
Reduced thirst mechanism results in decreased fluid intake.
Nurse must assess for these changes and implement treatment accordingly.
Fluid and Electrolyte Imbalances
Common in most patients with major illness or injury
- -Directly caused by illness or disease (burns or heart failure)
- -Result of therapeutic measures (IV fluid replacement or diuretics)
Extracellular Fluid Volume Imbalances
ECF volume deficit (hypovolemia)
- -Abnormal loss of normal body fluids (diarrhea, fistula drainage, hemorrhage), inadequate intake, or plasma-to-interstitial fluid shift
- -Treatment: Replace water and electrolytes with balanced IV solutions.
Fluid volume excess (hypervolemia)
- -Excessive intake of fluids, abnormal retention of fluids (HF), or interstitial-to-plasma fluid shift
- -Treatment: Remove fluid without changing electrolyte composition or osmolality of ECF.
Nursing Management Nursing Diagnoses
-Hypovolemia Deficient fluid volume Decreased cardiac output Risk for deficient fluid volume Potential complication: Hypovolemic shock
-Hypervolemia Excess fluid volume Risk for imbalanced fluid volume Ineffective airway clearance Risk for impaired skin integrity Disturbed body image Potential complications: Pulmonary edema, ascites
Fluid Deficit―Dehydration
-Insufficient body fluid
Inadequate intake
Excessive loss
Both
-Fluid loss often measured by change in body weight
-Dehydration more serious in infants and older adults
Water loss may be accompanied by loss of electrolytes and proteins (e.g., diarrhea).
