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Distribution, proportion and composition of body fluids
- ECF - fluid outside the cells 20% of body weight
- ICF (intracellular fluid)- fluid in the cells 40% of body weight
- water make up of the body 55 - 60 % and 55-55% in older adults
- The ECF space contains about one third (about 15 L) of the total body water. The ECF includes interstitial fluid (fluid between cells, sometimes called the “third space”. Excess fluid here is edema); blood, lymph, bone, and connective tissue water; and the transcellular fluids. Transcellular fluids are the fluids in special body spaces and include cerebrospinal fluid, synovial fluid, peritoneal fluid, and pleural fluid, digestive juices. ICF contains the remaining two thirds (about 25 L) of total body water.
- Intravascular fluid: is the plasma within the blood. Main function to trasport blood cells.
- solid substances thta dissolve in body fluid
- Cristalloids: solutes that readily dissolve (electrolytes)
- Colloids: are larger molecules that do not dissolve readily (proteins)
Electrolytes and nonelectrolytes
- Electrolytes: substances (sodium, potassium) that develop an electrical charge when disolved in water.
- Nonelectrolytes: are the other solutes that do not conduct electricity (glucose, urea)
Body fluids functions
- maintain blood volume
- regulate body temp
- transport material to and from cells
- serve as a medium for cellular metabolism
- assist with digestion of fod
- serve as a medium for excreting waste
- electrolytes that carry a positive charge they include
- Sodium (Na+), potassium (K+), Calcium (Ca+), and Magnesium (MG2+)
- electrolytes thatcarry a negative charge
- Chloride (Cl-), bicarbonate (HCO3-), phsphate (HPO42-), and sulfate (SO42-).
Compasition of bodyfluids
- In the ICF: major cations are potassium and magnesium. The major anion is phosphate.
- In the ECF: major electrolytes sodium, chloride and bicarbonate. Albumin mostly present in intravascular fluid.
- movement of fluid and solutes requires energy
- to go uphill
- maintains concentration gradient
- molecules move from an area of low concentration to an area of high concentration area with a help of ATP
- requires no energy.
- There are 3 passive transport systems are osmosis, diffusion and filtration.
- Movement of water across a membrane from an area of a less concetranted solution to an area of high concentrated solution.
- Osmolality: the concentration of solutes providing pressure in body fluids is called osmolality. Measure in osmoles which is number of particles of solutes per kilogram of water. Sodium is the greates determinant of intracelular osmolality and potassium is the greatest determinant of intracellular osmolality.
- Dynamics in the capillary bed: Osmosis and filtration act together at the capillary membrane to control both ECF and ICF volumes. Thirst mechanism help - when we loose water the blood becomes more concentrated then ICF and water moves out of cells into the blood to dilute it and cells shrink which act as thirst acivators.
- At the capilary level the fluid moves out from the capillary at the arterial end (becuase hydrostatic pressure is greater there) into theinterstitial space and moves from the interstitial space back into the capillary at the venous end - this movement of water is FILTRATION.
Isotonic, hypotonic and hypertonic solution
- Another term for osmolality is tonicity.
- Isotonic solution: a fluid that is of th esame osmolality as blood.
- Hypotonic: is of lower osmolality than blood. Water moves by osmosis from the vascular system into the cells.
- Hypertonic: contains a higher concentration of solutes than does blood. water moves by osmosis rom the cells into the ECF.
- Is the movement of water and smaller particles from an area of high pressure to one of low pressure.
- Hydrostatic pressure: is the force created by fluid within a closed system; it is resnposible for normal cicrulation of blood. Ex. blood flows from arterial system (high pressure) to veins (low pressure). Fluid moves through the capillary membrane, only solutes of a certain size can flow with it.
- Blood pressure is an example of a hydrostatic filtering force. It moves whole blood from the heart to capillaries where filtration can occur to exchange water, nutrients, and waste products between the blood and the tissues. One factor that determines whether fluid leaves the blood vessels and enters the tissue spaces (interstitial fluid) is the difference between the hydrostatic pressure of capillary blood and that of the interstitial fluid.
- Osmotic pressure: power of solution to draw water. A highly concetrated solution draws water and has high osmotic pressure.
- When hydrostatic pressure exceeds osmotic pressure, fluid leaves the vessels. This difference, known as the filtration pressure, represents the net pressures that move fluid and solutes.
- passive process by which molecules of a solute move through a cell membrane from an area of higher concentration to an area of lower concentration. MOvement occurs until concentraiton is equal on both sides of the membrane.
- Diffusion is important in the transport of most electrolytes and particles through cell membranes. Unlike capillary membranes, which permit the diffusion of most small-sized particles down a gradient, cell membranes are selective. They permit diffusion of some particles but not others.
Foods and substances that re high in sodium, potassium, calcium, and magnesium
- Sodium: table salt, soy sauce, cured pork, cheese, milk, processed foods, canned products, and foods preserved with salt.
- Potassium: bananas, oranges, apricots, figs, dates, carrots, potatoes, tomatoes, spinach, dairy products, and meats.
- Calcium: Common food sources include milk, milk products, dark green leafy vegetables, and salmon, as well as calcium-fortified foods such as breads and cereals
- Magnesium: high levels are present in green vegetables, cereal grains, and nuts.
- Hypovolemia: dificit fluid volume, regardles of the cuase. Occurs when there is a proportional loss of fluid and electrolytes from ECF.
- Dehydration: describes a state of negative fluid balance in which there is a loss of water from the intracellular, extreacellular or intravascular spaces. Loss of fluids increase serum osmolarity. Initially, heart rate increases and the blood vessels constrict. As the volume continues to e lost, the heart pumps faster but not as powerfully, resultingin a rapid, wake pulse, and orthostati hypotension which is known as hopovolemic shock. If it continues, other sysmptoms are dry skin and mucous membranes, dicrased skin adn tongue turgor, decreased urine output, and flat neck veins, muslce weakness, fatigue, feeling warm.
- CAUSES OF DEHYDRATION
- Isotonic fluid volume dificit: water and electrolyte lost in egual proportion (most common). Loss from plasma and interstitial space not ICF. No fluid shift (actula dihydration)
- Hypertonic: more water than electrolytes is lost. Water is shifted from the cells to the ECF, and cells shrink. (blood becomes hypertonic)
- Hypotonic: Fluid can shift between spaces due to electrolyte loss. Water moves into cells and they swell. This shift stimulates kidneys by heart hormones to excrete more fluid and therefore you become dehydrated.
- ASSESSMENT: to assess F&E imbalance use Gordon's functional health patterns pg. 178 in Iggy Chart 13-2
- Hypervolemia: excess fluid, in ECF. Most common in vascular space and or dilution of spesific electrolytes and blood components. Involves excessive retention of sodium and water in the ECF.
- Causes - excessive salt intake, disease affecting kidney or liver funtion or por pumping action of the heart.
- Symptoms - blood pressure elevated, pulse is bounding, resp incrased and shallow, neck veins distended, edema, skin is pale and cool. In sever cases - moist crackles in the lungs, dyspnea, and ascites(excess peritoneal fluid)
Assessing fluid balance
- Skin isevaluated for six components: color, temperature, moisture content, continuity, turgor, and edema.
- The status of the mucous membranes provides information about fluid and electrolyte balance.
- All of the vital signs reflect information about fluid, electrolyte, and acid–base balance.
- Measure all fluids consumed or excreted in a 24-hour period.
- ● If you suspect fluid volume deficit, be sure to assess the patient for orthostatic hypotension.
- ● Capillary refill and venous filling also offer information about fluid status.
- ● Respiratory rate and pattern, as well as breath sounds, offer clues about fluid, electrolyte, and acid–base status.
- ● Assess orientation, level of consciousness, reflexes, and fatigue.
- ● Monitoring daily change in weight is an accurate method of assessing fluid status.
Types of intravenous solutions
- ● Isotonic fluids (examples are lactated Ringer’s and 0.9% sodium chloride (normal saline). The osmolality of isotonic fluids is similar to that of blood serum. When infused, isotonic solutions remain inside the intravascular compartment. As a result, they are useful for clients with hypotension or hypovolemia. Monitor them carefully if the client is at risk for fluid volume excess due to congestive heart failure (CHF) or hypertension.
- ● Hypotonic solutions (examples are 5% dextrose [D5W] and 0.45% sodium chloride [D5½NS]). Hypotonic solution osmolality is less than serum. Infusion of these solutions pulls body water from the intravascular compartment into the interstitial fluid compartment. As the interstitial fluid is diluted, its osmolarity decreases, drawing water into the adjacent cells. Hypotonic fluid is used for hyperglycemic conditions, such as diabetic ketoacidosis, in which high serum glucose draws fluid out of the cells and into the vascular and interstitial compartments. Hypotonic fluids must be administered carefully to prevent a sudden fluid shift from the intravascular space to the cells.
- ● Hypertonic fluids (volume expanders, such as dextran and serum albumin). Hypertonic fluids have a higher osmolality than serum. When administered, they pull fluids and electrolytes from the intracellular and interstitial compartments into the intravascular compartment. Hypertonic fluids can help stabilize blood pressure, increase urine output, and reduce edema. Volume expanders are used to increase blood volume following severe loss of blood or plasma, such as in severe burns or hemorrhage.
Age related factors as thye influence body fluid distribution.
- pg. 174 in Iggy.
- Skin: CHANGE- loss of elasticity - RESULT- an unrealiable indicator of fluid status.
- Change - decreased turgor and dicreased oil production - result - dry, eadily damaged skin
- Renal: Change - dicreased glomerular filtration - result - poor excrettion of waste products.
- Change - dicreased concentrating capacity - result - increased water loss.
- Muscular: Change - decreased muscle mass - result - decreased total body water and greater risk of dehydration
- Neurological: Change - diminished thirst reflex - result - decreased fluid intake, increasing the risk of dehydration
- Endocrine: Change adrenal atrophy - result - poor regulartion of sodium and potassium, predisposing the patient to hyponatremia and hyperkalemia.
Hormones that regulate fluid and electrolyte balance
- WATER CONSERVATION
- Thirst: consume water
- ADH: kidneys reabsorb water. Stimulated when blood osmolarity is high especial increase in sodium, cells shrink and stimulate ADH release.
- Renin/angiotensin/aldosterone: vasoconstriction and kidney reabsorption of sodium and water
- Aldosterone: Stimulated when sodium in ECF is low and prevents water and sodium loss and from pottasium getting too high.
- Fluid balance - conpensatory mechanisms (baffers...)
- WATER EXCRETION
- ANP and BNP: cause increase in water filtration by kidneys, increase in sodium excretion, and decreased renin(aldosterone) production (opposite of RAAS)
- NPs hormones secreated by special cells of the heart during incrased blood volume and blood pressure.
Disorder that affect fluid and electrolyte balance
Fever: increased body temperature increases the rate at which fluids are lost. For every degree (Celsius) increase in body temperature above normal, a minimum of an additional 500 mL of body fluid is lost. The older adult begins to lose more body water at lower levels of fever.
Nursing diagnoses, related factors, key concepts and interventions for Dehydration
- _Deficient Fluid Volume related to excessive fluid loss or inadequate fluid intake
- _Decreased Cardiac Output related to decreased plasma volume
- _Impaired Oral Mucous Membrane related to inadequate oral secretions
- _Confusion (Acute or Chronic) related to neurologic changes
- _Risk for Falls related to orthostatic (postural) hypotension
- _Risk for Impaired Skin Integrity related to changes in fluid status and skin turgor
- _Potential for Dysrhythmias
- _Potential for Electrolyte Imbalances
- INTERVENTIONS: Management of dehydration aims to prevent injury, prevent further fluid losses, and increase fluid compartment volumes to normal ranges. Main strategies include patient safety, fluid replacement, and drug therapy. pg. 179-180 in iggy.
Nursing diagnoses, related factors, key concepts and interventions for Overhydration
- Assessment: usually have pitting edema. Other manifistations usually seen in cardiovascular, respiratory neuromuscular, integumentary and gastrointestinal system.
- Key features chart 13-5 pg 182. (increased pulse rate and bouding quality, elevated blood pressure, )
- Nursing diagnoses:
- Excess Fluid Volume related to compromised regulatory mechanisms (inability of the kidneys to maintain body fluid balance)
- _Deficient Knowledge (fluid restrictions, drug therapy, and manifestations of fluid excess) related to lack of exposure or lack of interest in learning
- _Potential for Electrolyte Imbalances
- _Potential for Hypertension
- _Potential for Pulmonary Edema
Priority nursing interventions for patients with fluid overload aim to ensure patient safety
, restore normal fluid balance
, provide supportive care
until the imbalance is resolved, and prevent future fluid overload
. Drug therapy, nutrition therapy, and monitoring
are the basis of intervention.
Sings and symptoms of fluid shift and what nursing actions should be used to prevent complications
- Fluid shift accurs due to the following and their signs and symptoms -
- Increased fluid volume: peripheral edema, pulmonary edema, hepatic dysfunction, cerebral edema, mental changes, dicreased cardiac output, jugular vein distention, hypertension.
- Increased capillary hydrostatic pressure:
- Decreased sodium level:
- Albumin losses:
- Increased capillary permeability: local edema as with trauma or systemic as with anaphylaxis
- Lymphatic system obstruction: locolized edema.
- In hypovolemia elevated hemoglobin and hematocrit.
- In hypervolemia dicreased values of hemoglobin and hematocrit.
- High or low levels of sodium and albumin.
- Weight gain or loss
- Edema of the abdominal tissue - ascites - inreased pressure and firmness of the abdomen
- To prevent complications: stabilizing patient's hymodynamic status is the first priority. Prevent hypovolemia and hypotension in loss phase. In reabospriton phase prevent circulatory overload and hypertension. To stebalized administer crystalloids that replace electrolytes and restore normal serum osmolality. And used isotonic, hypertonic or hypotonic solution.
- Monitor vital signs, urine output, perpheral perfusion. Mental status, ventilattion status, hematocrit, hemoglobin, serum electrolytes, abdominal pressure, continues administering fluid resuscitation (isotonic and intermittent colloid(albumin)
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