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1. What are the processes involved in regulating extracellular fluid volume, body fluid osmolality, and fluid distribution?
- Active transport: uses ATP to move electrolytes across cell membranes against the gradient. NA+ K+ pump is an example to keep K+ and NA+ outside the cell.
- Diffusion: passive movement of electrolytes down the gradient. They move until its equal. Requires protein to serve as an ion channel.
- Osmosis: Water moving through cell membranes to even out the concentration of water to solutes.
- Filtration: fluid moving into and out of the capillaries (between vascular and interstitial compartments). Hydrostatic pressure is the force of the fluid pressing outward against the surface and helps move fluids from capillaries into the interstitial area. This is strong at the arterial end of a normal capillary.
- Colloid osmotic pressure: inward-pulling force of protein that help move fluid from the interstitial area back into the capillaries. This is greater at the stronger at the venous end of the capillary and helps to remove waste. The lymph vessels remove any extra fluid and proteins that have leaked into the interstitial fluid.
2. How does the body maintain fluid balance through fluid intake, fluid distribution, and fluid output?
- Fluid intake and absorption: Orally, eating and eating should be around 2300 mL (1100-1140 of liquid, 800-1000 from food). Food metabolism creates additional water. Youre thirsty when plasma osmolality increases (osmoreceptor mediated) or blood volume decreases (baroreceptor medicated, angiotension I and III mediated).
- Fluid distribution: The term fluid distribution means the movement of fluid among its various compartments. Fluid distribution between the extracellular and intracellular compartments occurs by osmosis. Fluid distribution between the vascular and interstitial portions of the ECF occurs by filtration.: occurs between the IC and the EC by osmosis. Between vascular and interstitial portions of the ECF occurs by filtration.
- Fluid output: Consists of hypotonic sodium-containing fluid. Occurs through skin, lungs, GI and kidneys. Abnormally through vomit, wound drainage, or hemorrhage. Insensible (not visible) water loss through the skin and lungs is continuous. It increases when a person has a fever or a recent burn to the skin. Sweat, which is visible and contains sodium, occurs intermittently and increases fluid output substantially. The GI tract plays a vital role in fluid balance. Approximately 3 to 6 L of fluid moves into the GI tract daily and then returns again to the ECF. The average adult normally excretes only 100 mL of fluid each day through feces
- ADH- antidiuretic hormone: influences how much water is excreted in the urine. Comes from the posterior pituitary, made by the hypothalamus, and acts on the collecting ducts. Activated by dehydration, hemorrhage, pain, stress, and certain medications.
- RAAS- Renin-angiotensin: aldosterone system. The kidneys release renin, which acts on angiotensionogen secreted by the liver, and converts it to angiotensinogen 1, then the lungs convert that into angiotensionogen 2, and then that can vasocontrict some vascular beds or stimulate aldosterone release from the adrenal cortex. Aldosterone causes resorption of sodium in the DRT in the kidneys. This increases volume of the ECF. Aldosterone also increases urinary excretion of potassium and hydrogen ions.
- ANP: influences how much sodium and water are excreted in urine. Cells in the atria of the heart release ANP when they are stretched and it inhibits ADH by increasing loss of sodium in water and opposes the effect of aldosterone.
3. What are the causes of fluid imbalances?
- Short answer:
- There are two major types of fluid imbalances: volume imbalances and osmolality imbalances.
- Volume imbalances are disturbances of the amount of fluid in the extracellular compartment.
- Osmolality imbalances are disturbances of the concentration of body fluids.
- Volume and osmolality imbalances occur separately or in combination.
- Long answer: Table 41-3
- Diseases process, medications. Diarrhea, dehydration.
- Extracellular fluid volume imbalance: Too much or too little. ECV deficit, output of isotonic fluid exceeds intake sodium-containing fluid. Extracellular fluid is both vascular and interstitial, signs and symptoms arise in both compartments. ECV excess happens when there is too much isotonic fluid in the EC compartment. Intake exceeds output like when you eat more salty foods and water.
- Osmolality imbalance: Body fluids become hypertonic or hypotonic, which causes water to shift across cell membranes causing hyper or hyponatremia.
- Hypernatremia: water deficit, highly concentrated.
- Hyponatremia: water excess, dilute.
- When ECV deficit and hypernatremia often occur at the same time and this is called clinical dehydration. The ECV is too low and the body fluids are too concentrated.
4. What risk factors are associated with fluid imbalance?
- Short answer: Old age, young age, Sodium-rich diet, how weather, diarrhea, drainage, vomiting, Cirrhosis, Heart failure, oliguric renal disease, burns, hemorrhage, diuretics and other medications, IV therapy, parental nutrition.
- Long answer:
- 1. Very Young are at risk for: ECV deficit, Osmolality Imbalances, Clinical dehydration
- 2. Very Old are at risk for: ECV excess or deficit, Osmolality imbalances
- Sodium rich diet increases risk for: ECV excess
- Electrolyte poor diet increases risk for electrolyte deficit
- Hot weather increases risk for clinical dehydration
- Gastrointestinal Output:
- 1. Diarrhea increases risk for: ECV deficit, Clinical dehydration, Hypokalemia, Hypocalcemia (if chronic), Hypomagnesemia (if chronic), Metabolic Acidosis
- 2. Drainage increases risk for: ECV deficit, Hypokalemia, Metabolic acidosis if intestinal or pancreatic drainage
- 3. Vomiting increases risk for: ECV deficit, Clinical dehydration, Hypokalemia, Hypomagnesemia, Metabolic Alkalosis
- Chronic disease:
- 1. Cancer increases risk for: Hypercalcemia,
- With tumor lysis syndrome:
- 2. Cirrhosis increases risk for: ECV excess, Hypokalemia
- 3. Heart failure increases risk for: ECV excess,
- 4. Oliguric renal disease increases risk for: ECV excess, Hyperkalemia, Hypermagnesemia, Hyperphophatemia, Metabolic acidosis
- 1. Burns increase risk for: ECV deficit, Metabolic Acidosis,
- 2. Crush injuries increase risk for: Hyperkalemia,
- 3. Head injuries increase risk for: Hyponatremia or hypernatremia depending on ADH response
- 4. Hemorrhage increases risk for: ECV deficit, Hyperkalemia if circulatory shock
- 1. Diuretics and other medications
- IV therapy increases risk for: ECV excess, Osmolality imbalances, Electrolyte excess
- 2. PN (parenteral nutrition) increases risk for: Any fluid or electrolyte imbalance depending on the components of the solution
5. What nursing assessment questions would the nurse ask related to fluid balance/imbalance?
Box 41-1 Nursing Assessment Questions
- Do you work or exercise in a hot environment?
- If so, which type of fluid do you drink during that time? type of fluids do you drink?
- Dietary Intake
- How much do you usually drink every day? Which type of fluids do you drink?
- Tell me what you eat in a typical day.
- Which snacks do you usually eat?
- Are you on a special diet because of a medical problem? How does that work for you?
- Are you following any weight loss program?
- Do you use a salt substitute?
- Do you take calcium, magnesium, or potassium supplements? If so, how often?
- Do you have any difficulties chewing or swallowing?
- How much alcohol do you drink in a typical week?
- Gastrointestinal Output
- Have you had recent vomiting or diarrhea? If so, for how long? How many times per day?
- Medications and Other Therapies
- Which medications/herbal remedies do you use regularly? Occasionally?
- Do you take diuretics? Drugs for high blood pressure?
- Do you use antacids? If so, which ones? How often? Do you ever use baking soda as an antacid? Do you use fizzy (effervescent) medications for colds?
- Do you use laxatives? If so, how often? Which type of stool do you get when you use them?
- What do you use for an upset stomach?
- Signs and Symptoms
- If you weigh yourself every day, how has your weight changed over the past few days?
- Do you get light-headed when you stand up?
- Do you feel thirsty, have a dry mouth, or notice a lack of tears?
- Have you noticed a change in your urine output; decreased volume, dark color, or concentrated or ankles?
- Do you have difficulty breathing when you lie down at night?
- Are you having difficulty concentrating, or do you feel confused? What is normal for you?
- Are you having more difficulty than usual standing up from a sofa or soft chair? Do your legs feel unusually heavy when you climb stairs? Do you have muscle weakness that is unusual for you?
- Have you noticed any muscle cramps or unusual sensations such as numbness or tingling fingers?
6. How would fluids be replaced by the enteral route?
Oral replacement hat is used if the patient is stable enough. Contraindicated when the patient has a obstruction of he GI tract, high risk for aspiration, or has impaired swallowing. Offer small sips of fluid frequently, popsicles, and ice chips (recorded as 1/2 volume of ice chips). A feeding tube is appropriate when the patient's GI tract is health but the patient cannot ingest fluids because of oral surgery or impaired swallowing.
7. How would fluids be replaced by the parenteral route?
Fluid and electrolytes may be replaced through infusion of fluids via IV. Includes PN, IV fluid and electrolyte therapy (crystalloids) and blood and blood component administration (colloid). PN AKA TPN (total parenteral nutrition) is administration of a complex, highly concentrated solution containing nutrients and electrolytes that is formulated for a patients needs.
8. What are the different types of intravenous solutions and what are the concentrations of each? (Table 41-11)
- *Dextrose in water (glucose):
- Dextrose 5%-isotonic-dextrose enters cells rapidly leaving free water, which dilutes ECF, most of the water then enters cells by osmosis. (D5W)
- Dextrose 10%-hypertonic-dextrose enters cell rapidly, leaving free water which diluted ECF, most of the water then enters cells by osmosis. (D10W)
- *Saline solutions (sodium chloride in water):
- 0.225% sodium chloride-hypotonic-expands ECV (vascular and intersitial) and rehydrates cells (quarter normal saline, 1/4 NS; 0.225% NaCL).
- 0.45% sodium chloride-hypotonic-expands ECV (vascular and interstitial) and rehydrates cells (half normal saline, 1/2 NS, 0.45% NaCL).
- 0.9% sodium chloride-isotonic-expands ECV (vascular and intersitial) does not enter cells (normal saline, NS, 0.9% NaCL)
- 3% or 5% sodium chloride-hypertonic-draws water from cells into ECF by osmosis (hypertonic saline, 3% or 5% NaCL)
- *Dextrose in Saline Solutions
- Dextrose 5% in 0.45% NaCL sodium chloride-hypertonic-dextrose enters cells rapidly leaving 0.45 sodium chloride.
- Dextrose 5% in 0.9% sodium chloride-hypertonic-dextrose enters cells rapidly, leaving 0.9% sodium chloride.
- *Balanced Electrolyte Solutions
- Lactated Ringers-Isotonic-Contains NA+,K+,CA2+, Cl-, and lactate, which the liver metabolizes to HCO-3. This expands ECV (vascular and interstitial) does not enter the cells.
- Dextrose 5% in lactated ringers-hypertonic-dextrose enters cells rapidly leaving lactated ringers.
9. Demonstrate correct technique for spiking, priming and labeling of IV fluids.
- 10. Demonstrate correct technique for flushing saline lock; starting IV fluids.
- 11. Demonstrate correct documentation of IV fluids.
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