FLUID, ELECTROLYTE, AND ACID-BASE BALANCE

NUR 102 - Chapter 14

Body fluids

Extracellular fluids (ECF)• Interstitial fluid - fills the spaces between most

cells of the body

• Intravascular fluid - plasma (WBC, RBC and platelets in this fluid)

Body fluids

Intracellular fluids (ICF)• Liquids within cell membranes

• 40% of body weight

Components in body fluids

Electrolyte• an element that when dissolved can carry an

electrical current

• Cations - (+) ; Anions - (-)

• neuromuscular function

• acid-base balance

Components of body fluids

Minerals• ingested compounds

• serve as catalysts in nerve response, muscle contraction, and metabolism of nutrients in foods, regulate electrolyte balance

Movement of body fluids

Diffusion• Area of higher concentration to an area of

lower concentration till even distribution

Osmosis• Movement of a pure solvent, e.g. water

through a semipermeable membrane from a solution that has a lower solute concentration to one that has a higher solute concentration

Osmotic pressure

Drawing power of water (dependent on the number or molecules in solution)• Isotonic

• Hypotonic

• Hypertonic

Movement of body fluids

Filtration• Water and diffusible substances move

together in response to fluid pressure

Active transport• Requires energy

• Able to move larger molecules and go from less to greater concentration

Fluid Intake

Hypothalamus - thirst control center Oral fluid intake requires an alert state Osmoreceptors - monitor osmolality

Fluid Output

Loss through the kidneys and GI tract Insensible Sensible

Cations

Sodium (Na+)• Most abundant in the extracellular fluid

• Maintains water balance, transmits nerve impulses, contracts muscles

• Values - 135-145 mEq/L

Cation

Potassium (K+)• Major intracellular cation

• Regulates neuromuscular excitability, muscular contraction, and acid-base

• Value - 3.5 -5.3 mEq/L

Cation

Calcium (Ca2+)• Cardiac conduction, blood coagulation, bone

growth and formation, & muscular relaxation

• Value - 4 - 5 mEq/L

Cation

Magnesium (Mg2+)• Second most important of intracellular fluids

• Enzyme activities, muscular excitability

• Value - 1.5 - 2.5 mEq/L

Electrolyte Imbalances

Hyponatremia • GI losses, sweating, & diuretics

• S/S: N/V/D, abd cramps, personality change

Hypernatremia• Ingestion of large amounts

• S/S: Dry tongue and mucous membranes, restlessness, convulsions, thirst, dry skin

Electrolyte imbalances

Hypokalemia Causes: K+ wasting diuretics N/V/D polyuria S/S: weak, irregular pulse

• hypotension

• weakness

Electrolyte imbalances

Hyperkalemia• Causes: Renal failure

• S/S: irregular slow pulse, weakness, irritability

Electrolyte Imbalances

Hypocalcemia• Causes: Vitamin D deficiency

• S/S: Numb and tingling fingers and circumoral region, muscle cramps

Hypercalcemia• Causes: osteoporosis, prolonged

immobilization

• S/S: decreased muscle tone, weakness, lethargy, kidney stones

Electrolyte imbalances

Hypomagnesemia• Causes: malnutrition and alcoholism polyuria

• S/S: muscular tremors, hyperactive deep tendon reflexes

Hypermagnesemia• Causes: Renal failure

• S/S: hypoactive deep tendon reflexes, shallow and slow respirations

Acid - Base Balance

Blood pH - 7.35 - 7.45 paCO2 - 35 - 45 Bicarbonate (HCO3) - 22-26 mEq/L

Respiratory Acidosis

pH < 7.35 paCO2 > 45 mm Hg Causes: Respiratory failure Hypoventilation Resp muscles paralysis Airway obstruction

Respiratory Alkalosis

pH > 7.45 paCO2 < 35 mm Hg Causes: excessive exhalation of CO2

(hyperventilation)

Metabolic Acidosis

pH < 7.35 bicarbonate - < 22 mEq/L Causes: Starvation, DKA, Diarrhea, drug

use

Metabolic Alkalosis

pH > 7.45 bicarbonate > 26 mEq/L Causes: excessive vomiting, prolonged

gastric suctioning

Fluid & Electrolyte Imbalances

Burns - body fluid loss Renal D/O - abnormal retention of Na,

Cl, K GI Disturbances - Loss of fluid,

potassium, and chloride Exercise

S/S electrolyte imbalance

Head: irritability Fontanels: depressed, bulging Eyes: sunken

periorbital edema

Mouth: mucous membranes CV: neck veins, edema, blood pressure Resp: Crackles

Imbalances

GI: abdomen, V/D Renal: Oliguria or anuria (FVD, FE) Diuresis (FVE) Increased urine spec. gravity (FVD) Skin (Temp)

• increased - met acidosis, hypernatremia

• decreased - FVD

Replacement of fluids and electrolytes

Types of IV fluids Isotonic Hypertonic Hypotonic

IV complications

Infiltration • IVF enter SQ space

Phlebitis• vein inflammation

• S/S: pain, redness, warmth

Fluid overload• Fluids given too rapidly

Bleeding

Discontinuing an IV

Stop infusion Remove tape 1 - 2 minute pressure

Blood transfusions

Large bore catheter (18 ga or larger) Give with normal saline Baseline vital signs Double check with two RNs Begin transfusion slowly Observe closely for first 15 min

Transfusion Reactions

Caused by: • blood incompatibility

• allergic sensitivity

• S/S: fever, chills, rash, hypotension, shock

Treatment: stop transfusion, give NS, save tubing, prepare for emergency drugs