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FLUID, ELECTROLYTE,AND ACID-BASE BALANCE

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Anatomy and Composition of

Fluid Compartments

Total Body Water (TBW) adult

45-70% of body weight

lowest in aged & obese

highest in very lean & young

TBW 60% -- male 70kg

50-55% female

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Anatomy and Composition of

Fluid Compartments

The composition of body fluid:

Two compartments

Intracellular Space -- 2/3 -- 40%

Extracellular Space -- 1/3 -- 20%

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Body fluids Extracellular fluids (ECF)

Interstitial fluid - fills the spaces

between most cells of the body15% of body weight

Intravascular fluid - plasma

(WBC, RBC and platelets

in this fluid)

5% of body weight

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Body fluids

Intracellular fluids (ICF)

Liquids within cell membranes

40% of body weight

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Amount and composition of

body fluids

Actual amount of body water

differs according to

Age

Sex

Body composition

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Physiology of Body WaterBalanceNewborn70% 0f WT water

1-year-old60% of WT water

Men: higher water contentdue to greater muscle mass

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Physiology of Body WaterBalanceObese: less water because fat

cells have minimal ICF

Use ideal body weight whenestimating TBW for obese

Elderly: less water due to lessmuscle mass

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Fluid Shifts

Third Spacing

Refers to loss of ECF into a space that doesnot contribute to equilibrium between ICFand ECF

Excess fluid in interstitial spaces and connective tissuesbetween cells [edema] or

Excess fluid in potential spaces [effusion]

peritoneal cavity

pericardial sac

synovial cavities of joints

alveoli or intra-pleural space

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Fluid Shifts

Third Spacing

Etiology

Caused by an increase in filtration

and/or decrease in reabsorptiondue to altered capillary forces

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Fluid Shifts

Third Spacing

Mechanisms causing thirdspacing & edema

massive inflammationvenous obstruction

increased blood volume

low serum albumin

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Components in body fluids

Electrolyte

an element that when dissolved can carry an

electrical current Cations - (+) ; Anions - (-)

neuromuscular function

acid-base balance

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Components of body fluids

Minerals

ingested compounds

serve as catalysts in nerve response, musclecontraction, and metabolism of nutrients infoods, regulate electrolyte balance

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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. waterthrough a semipermeable membrane from a

solution that has a lower solute concentrationto one that has a higher solute concentration

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Osmotic pressure

Drawing power of water (dependent onthe number or molecules in solution)

Isotonic

Hypotonic

Hypertonic

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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 fromless to greater concentration

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Fluid Intake

Hypothalamus - thirst control center

Oral fluid intake requires an alert state

Osmoreceptors - monitor osmolality

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Fluid Output

Loss through the kidneys and GI tract

Insensible

Sensible

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Cations

Sodium (Na+)

Most abundant in the extracellular fluid

Maintains water balance, transmits nerveimpulses, contracts muscles

Values - 135-145 mEq/L

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Cation

Potassium (K+)

Major intracellular cation

Regulates neuromuscular excitability,muscular contraction, and acid-base

Value - 3.5 -5.3 mEq/L

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Cation

Calcium (Ca2+)

Cardiac conduction, blood coagulation, bone

growth and formation, & muscular relaxation Value - 4 - 5 mEq/L

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Cation

Magnesium (Mg2+)

Second most important of intracellular fluids

Enzyme activities, muscular excitability

Value - 1.5 - 2.5 mEq/L

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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

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Electrolyte imbalances

Hypokalemia

Causes: K+ wasting diuretics

N/V/D

polyuria

S/S: weak, irregular pulse

hypotension

weakness

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Hyperkalemia

Causes: Renal failure

S/S: irregular slow pulse, weakness, irritability

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Electrolyte Imbalances

Hypocalcemia

Causes: Vitamin D deficiency

S/S: Numb and tingling fingers and circumoralregion, muscle cramps

Hypercalcemia

Causes: osteoporosis, prolongedimmobilization

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

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Hypomagnesemia

Causes: malnutrition and alcoholism polyuria

S/S: muscular tremors, hyperactive deeptendon reflexes

Hypermagnesemia

Causes: Renal failure

S/S: hypoactive deep tendon reflexes, shallowand slow respirations

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Acid - Base Balance

Blood pH - 7.35 - 7.45

paCO2 - 35 - 45

Bicarbonate (HCO3) - 22-26 mEq/L

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Respiratory Acidosis

pH < 7.35

paCO2 > 45 mm Hg

Causes: Respiratory failure

Hypoventilation

Resp muscles paralysis

Airway obstruction

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Respiratory Alkalosis

pH > 7.45

paCO2 < 35 mm Hg

Causes: excessive exhalation of CO2(hyperventilation)

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Metabolic Acidosis

pH < 7.35

bicarbonate - < 22 mEq/L

Causes: Starvation, DKA, Diarrhea, druguse

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Metabolic Alkalosis

pH > 7.45

bicarbonate > 26 mEq/L

Causes: excessive vomiting, prolongedgastric suctioning

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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

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S/S electrolyte imbalance

Head: irritability

Fontanels: depressed, bulging

Eyes: sunkenperiorbital edema

Mouth: mucous membranes

CV: neck veins, edema, blood pressure Resp: Crackles

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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

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Replacement of fluids and

electrolytes

Types of IV fluids

Isotonic

Hypertonic Hypotonic

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IV complications

Infiltration

IVF enter SQ space

Phlebitis vein inflammation

S/S: pain, redness, warmth

Fluid overload Fluids given too rapidly

Bleeding

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Discontinuing an IV

Stop infusion

Remove tape

1 - 2 minute pressure

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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

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Transfusion Reactions

Caused by:

blood incompatibility

allergic sensitivity

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

Treatment: stop transfusion, give NS,save tubing, prepare for emergencydrugs

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