Chapter 40

kidneys:

"master chemists" of the body selectively retain electrolytes and water and excrete wastes and excesses according to the bodys needs

hypomagnesium

-a magnesium deficit -may occur with nasogastric suction, diarrhea, withdrawal from alcohol, administration of tube feedings, or parenteral nutrition, sepsis, or burns -may lead to muscle weakness, tremors, tetany, seizures, heart block, chance in mental status, hyperactive deep tendon reflexes, and respiratory paralysis

hypermagnesemia

-a magnesium excess -usually occurs with renal failure (when the kidneys fail to excrete magnesium) -clinical manifestations include: nausea, vomiting, weakness, flushing, lethargy, loss of DTR's, respiratory depression, coma, and cardiac arrest

hypernatremia

-a surplus of sodium caused by excess water loss or an overall excess of sodium -could be caused by fluid deprivation, lack of fluid consumption, diarrhea, and excess insensible water loss

hyperchloremia

-above normal level of chloride

hyperphosphorus

-above-normal concentrations of phosphorus

hyperkalemia

-an excess of potassisum -may be a result from renal failure, hypoaldosteronism, or the use of certain medications

hypophosphorus

-below normal concentration of phosphorus

hypochloremia

-below normal level of chloride

hypocalcemia

-calcium deficit -manifestations may include: numbness/tingling of fingers, mouth or feet; tetany; muscle cramps; and seizures

hypercalcemia

-excess of calcium -2 major causes are cancer and hyperparathyroidism -manifestations include: vomiting, nausea, constipation, bone pain, excessive urination, thirst, confusion, constipation, lethargy, and slurred speech

hypokalemia

-refers to a potassium deficit and is common electrolyte abnormality -may be lost through vomiting, gastric suction, alkalosis, diarrhea, or as the result of diuretic use -could cause muscle weakness and leg cramps, fatigue, paresthesias, dysrhythmias

hyponatremia

-sodium deficit caused by loss of sodium or loss of water -may be lost through vomiting, diarrhea, fistulas, sweating, or as the result of the use of diuretics -could cause confusion, hypotension, edema, muscle cramps, weakness, and dry skin

rate of administration for packed red blood cells

1 unit over 2 to 3 hours, no longer than 4 hour.

the desirable amount of fluid intake and loss, range:

1500-3500 (averaging 2500-2600) mL per day

average fluid output:

2500 to 2900 mL per day (average 2600)

total amount of water weight in a health person

50-60%

normal pH range

7.35-7.45

what should a nurse consider before starting an IV?

Ensure that the prescribed solution is clear and transparent.

protein buffer system

a mixture of plasma proteins and the globin portion of hemoglobin in red blood cells

respiratory acidosis

a primary excess of carbonic acid in the ECF, its produced by inadequate excretion of CO2 with inadequate ventilation, resulting in elevated plasma CO2 and increased levels of carbonic acid

active transport

a process that requires energy for the movement of substances through a cell membrane from an area of lesser solute concentration to an area of higher solute concentration

antibody

a protein substance developed in the body in response to the presence of an antigen that has entered the body

isotonic

a solution that has about the same concentration of particles, or osmolarity, as plasma

antigen

a substance that causes the formation of antibodies

buffer

a substance that prevent body fluid from becoming overly acidic or alkaline. they combine w/ excess acids or bases to prevent major changes in pH

gastrointestinal tract:

absorbs water and nutrients that enter the body through this route

edema

accumulation of fluid in the interstitial space. can be observed around the eyes, fingers, ankles, and sacral space, and can also accumulate around body organs

phosphate buffer system

active in intracellular fluids, especially in the renal tubules. It converts alkaline sodium phosphate, a weak base, to acid-sodium phosphate

nervous system:

acts as a switchboard to inhibit and stimulate mechanisms that influence fluid balance, functions chiefly as the regulator of sodium and water intake and excretion

extracellular fluid

all the fluid outside the cells, accounting for about 30% of the total body water or 20% of the adults body weight

agglutinin

an antibody that causes a clumping of specific antigens

ion

an atom or molecule carrying an electrical charge

metabolic alkalosis

an excess of HCO3, a decrease of H+ ions, or both. this may be the result of excessive acid losses or increased base ingestion or retention

Rh factor

an inherited antigen in human blood

What is the lab test commonly used in the assessment and treatment of acid-base balance?

arterial blood gas

when developing a teaching plan for a patient at risk for hyperkalemia, which foods would the nurse instruct the patient to avoid?

bananas and apricots because these foods are high in potassium

Rh-positive person

blood is administered to an Rh-negative person, the recipient develops anti-Rh agglutinins

Sensible losses

can be measured, and include fluid lost during urination, defecation, and wounds.

Insensible losses

cant be measured or seen, and include fluid lost from evaporation through the skin and as water vapor from the lungs during respiration

hyperkalemia: what should the nurse monitor for?

cardiac irregularities

what would the nurse use as the most reliable indicator of a patients fluid balance status?

daily weight

monitoring a patients fluid balance

daily weights are considered one of the more accurate measures of fluid balance.

serum electrolytes, bun, and creatinine levels

determines plasma levels of certain electrolytes such as sodium, potassium, chloride, and bicarbonate ions

complete blood count

determines the total number of red blood cells and values for hemoglobin and hematocrit

autologous transfusion

donating your own blood for a transfusion

diuretics

drugs that increase renal excretion of water, sodium, and other electrolytes. they can increase the risk for fluid volume deficit and serious electrolyte deficiencies

hypervolemia

excess of isotonic fluid

A common cause of fluid volume excess

failure of the heart to function as a pump, resulting in accumulation of fluid in the lungs and dependent parts of the body.

hypovolemia

fluid volume deficit can be caused by a loss of both water and solutes in the same proportion from the ECF space, this state is commonly known as hypovolemia

hypertonic

has a greater osmolarity than plasma

hypotonic

has less osmolarity than plasma

lab studies

helpful in determining whether fluid, electrolyte, and acid-base balance exist

where does the human body obtain water from?

ingested liquids, ingested foods, and as a by-product of metabolism

fluid intake

ingested water: 1300 ingested food: 1000 metabolic oxidation: 300 total: 2600

plasma, the liquid constituent of blood, is correctly identified as, what?

intravascular fluid

anions

ions with a negative charge

cations

ions with a positive charge

fluid output

kidneys: 1500 skin: 600 lungs: 300 gastrointestinal: 200 total: 2600

arterial blood gases

lab tests commonly used to determine the adequacy of oxygenation and ventilation

Rh-negative person

lacks this D antigen and must receive blood from another Rh-negative person

solvents

liquids that hold a substance in solution (water is the primary solvent of the body)

common causes of hypervolemia

malfunction of the kidneys and failure of the heart to function as a pump

what acid-base imbalance would the nurse suspect after assessing the following arterial blood gas values (pH 7.30, PaCO2, 36 mm Hg, HCO3-, 14 mEq/L)

metabolic acidosis: a low pH indicates acidosis and a low bicarbonate indicates metabolic acidosis

daily weights

more accurate then input/output. weight the pt at the same time everyday

alkalosis

occurs when there is a lack of H ions or a gain of base (bicarbonate) (pH exceeds 7.45)

what does water move by?

osmosis

respiratory alkalosis

primary deficit of carbonic acid, breathing is faster and deeper

metabolic acidosis

proportionate defecit of bicarbonate, the deficit can occur as the result of an increase in acid components or an excessive loss of bicarbonate

third-space fluid shift

refers to a distributional shift of body fluids into the transcellular compartment

lungs:

regulate oxygen and carbon dioxide levels of the blood

thyroxine:

released by the thyroid gland, increases blood flow in the body, leading to increased renal circulation and resulting in increased glomerular

in which acid-base imbalance would the nurse instruct a patient to focus on breathing more slowly?

respiratory alkalosis (carbonic acid deficit)

cardiovascular system:

responsible for pumping and carrying nutrients and water throughout the body

adrenal glands:

secrete aldosterone, a mineralocorticoid hormone that helps the body conserve sodium, helps save chloride and water, and causes potassium to be excreted

parathyroid glands:

secrete parathyroid hormone which regulates the level of calcium and phosphorus

neurons

sensitive to changes in the concentration of ECF, sending the appropriate impulses to the pituitary glands to release ADS or inhibit its release to maintain ECF volume concentration

electrolytes

substances that are capable of breaking into particles called ions

solutes

substances that are dissolved in a solution

colloid osmotic pressure

the "pulling" force

hydrostatic pressure

the "pushing" force

osmolarity

the concentration of particles in a solution, or its pulling power, is referred to as the osmolarity of a solution

acidosis

the condition characterized by an excess of H ions or loss of base ions (bicarbonate) (pH falls below 7.35)

intracellular fluid

the fluid within the cells, constituting about 70% of the total body water or 40% of the adults body weight

typing

the lab examination to determine a persons blood type is called typing

what does potassium function as?

the major cation of intracellular fluid

osmosis

the major method of transporting body fluids. through the process of osmosis, water passes from an area of lesser solute concentration and less water until the equilibrium is established

carbonic buffer system

the most important buffer system in the body, important for acid-base balance, 20:1 ratio os bicarbonate to carbonic acid

filtration

the passage of fluid through a permeable membrane

cross-matching

the process of determining compatibility between blood specimens is cross-matching

diffusion

the tendency of solutes to move freely throughout a solvent

hypothalamus

the thirst center located in the brain

milliequivalent:

the unit of measure that describes the chemical activity of electrolytes. 1 milliequivalent of a cation or anion is chemically equivalent to the activity of 1 mg of hydrogen

pH

the unit of measure used to describe acid-base balance

who is at risk for hypovolemia?

young children, elderly people, and people who are ill