fluid and electrolytes

characteristics of body fluids

• fluid amount (volume)

• composition (electrolyte conc)

• degree of acidity (pH)

fluid

water with dissolved or suspended substances - like glucose, mineral salts, proteins

osmolality

concentration of particles in a solution

isotonic

two solutions have same concentration of solute

hypertonic

one solution has greater concentration of solute than another

first solution exerts greater osmotic pressure

hypertonicity

excessive tension of the arterial walls or muscles

hypotonic

one solution has a smaller concentration of solute than another

first solutions exerts less osmotic pressure

hypotonicity

reduced tension of the arterial walls or muscles

extracellular fluid (ECF)

body fluid composed of interstitial fluid and blood plasma

1/3 of fluid

intracellular fluid

liquid within the cell membrane

intravascular fluid

fluid in blood vessels (plasma)

transcellular fluid

fluid in special compartments

what percent of body is water

• 50% for elderly

• 60% for adults

• 70-80% for infants

fat vs mm

fat contains less water than mm

active transport

need ATP to move particle against a gradient

diffusion

passive movement, high to low conc

osmosis

movement of water from low to high solute conc

filtration

passive movement of fluid and solutes across membrane b/c of hydrostatic pressure (capillaries)

fluid intake

• need around 2300mL a day

• intake options: food, drink, enema

fluid output

• skin

• GI

• kidneys

• lungs

• urine

• vomit

hypovolemia

fluid deficit in extracellular space

hypervolemia

fluid in excess in extracellular space

normal range for Na+

135 - 145 mEq/L

hypernatremia

• high Na+

• water deficit so solution is hypertonic (more solute)

• water flows out of the cells (shrink)

hyponatremia

• low Na+

• excess, so solution is hypotonic (less solute)

• water flow into cell (swell)

normal K+ range

3.5 - 5.0 mEq/L

hypokalemia

• low K+

• symptoms - muscle weakness

• causes - non K+ sparing meds, vomiting, acute diarrhea

hyperkalemia

• high K+

• symptoms - cardiac dysrhythmia, mm weakness

• causes - K+ sparing meds, kidney failure/disease, low output (oliguria)

normal Ca++ range

8.5 - 10.5 mg/dL

hypocalcemia

• low Ca+

• symptoms - numbness/tingling, mm cramps, nerve excitability, hyperactive reflexes

• causes - post menopause, chronic diarrhea, laxatives, pancreatitis

hypercalcemia

• high Ca+

• symptoms - lethargic, decreased LOC/confusion, nausea/vomiting, fatigue

• causes - diuretics, immobility

normal Mg+ range

1.3 - 2.1 mEq/L

hypomagnesemia

• low Mg+

• symptoms - mm cramps, increased DTR, HTN, increased BP, neuromuscular problems

• causes - alcohol, older pts, chronic diarrhea, laxatives, diuretics

hypermagnesemia

• high Mg+

• symptoms - decreased DTR, decreased HR, hypotension

• causes - kidney failure/renal disease

what is DTR

deep tendon reflex - involuntary mm contractions

normal pH

7.35 - 7.45

what is respiratory acidosis

lungs can’t move enough CO2 = CO2 build up in blood → make carbonic acid

respiratory acidosis findings

• pH below 7.35

• high CO2 (above 45mmHg)

causes and symptoms of respiratory acidosis

• causes

  • COPD

  • drug overdose

  • airway obstruction

  • respiratory depression

• symptoms

  • confusion, hypoxia, dyspnea, warm/flushed skin due to vasodilation

what is respiratory alkalosis

too much CO2 exhaled (hyperventilation)

respiratory alkalosis findings

• pH above 7.45

• low CO2 (below 35mmHg)

causes and symptoms of respiratory alkalosis

• causes

  • hyperventilation

• symptoms

  • lightheaded, dizzy, mm cramps, tingling

what is metabolic acidosis

too much acid or not enough bicarbonate

metabolic acidosis findings

• pH is below 7.35

• HCO3 (bicarbonate) is low (under 22mEq/L)

• low CO2

causes and symptoms of metabolic acidosis

• causes

  • diabetic ketoacidosis

  • lactic acidosis

  • severe diarrhea

  • renal failure

• symptoms

  • kussmaul respiration (deep/rapid breathing), confusion, nausea/vomiting

what is metabolic alkalosis

too much bicarbonate or not enough acid

metabolic alkalosis findings

• pH above 7.45

• HCO3 (bicarbonate) is high (over 26 mEq/L)

• high CO2

causes and symptoms of metabolic alkalosis

• causes

  • vomiting

  • diuretics

• symptoms

  • hypokalemia (low K+)

  • confusion

  • slow shallow respirations

vomit vs diarrhea

• vomit - lose acid

• diarrhea - lose base