Fluid and Electrolyte

F&E Balance Definition

regulation of water and electrolytes to create homeostasis

Why is F&E critical?

-Cellular function

-tissue functions

-organ function

-overall homeostasis

What is the role of renal?

excretion of water and electrolytes

What is the role of the lungs

acid base balance

What is the role of the heart

ensures adequate perfusion to the tissue

What is the role of the brain

regulates and monitors serum osmolality which triggers the thirst reflex

Fluid volume

Regulated through the movement and distribution of fluids through different body compartments

Acid-Base Balance

The regulation of H+ ions to maintain a normal pH in the body

Major solutes (ICF)

O2, electrolytes, and glucose

Major Cations (+) (ICF)

K+, Mg2+

Major anions (-) (ICF)

Phosphate, sulfate

Percentage of water: fetus (gestation)

100%

Percentage of water: Infants

70-80%

Percentage of water: Healthy YA

50-60% of water

Percentage of water: Older adult

about 50% water

What dictates the amount of water an individual may have in their body?

The more muscle mass = more water

Types of ECF

- interstitial fluid

- intravascular

- transcellular

Principle ECF electrolytes

- Na+

- Cl-

- bicarbonate (HCO3-)

- Low concentration: K, Ca, Mg

Intravascular fluid

Fluid within the blood vessels (arteries, veins, and capillaries), representing the liquid portion of blood (plasma and serum).

Interstitial Fluid

Fluid occupying the spaces between the cells and tissues

Transcellular Fluid

Fluid within specialized compartments, such as cerebrospinal fluid, synovial fluid, or peritoneal fluid

Osmosis

Movement of water through a semi-permeable membrane from low to high solute concentration.

Diffusion

Passive movement of particles from an area of higher to lower concentration.

Facilitated Transport

Passive movement across a membrane using a protein carrier without requiring energy. High to low concentration

Filtration

Passive movement of fluid through a membrane driven by pressure. High to low pressure

Hydrostatic Pressure

Water-pushing pressure exerted by fluid within the blood vessels.

Oncotic Pressure

Pressure created by proteins like albumin that holds fluid within the intravascular space.

Active Transport

Movement of solutes against a concentration gradient requiring cellular energy (ATP). Low to high concentration

Aldosterone

RAAS hormone secreted by the adrenal cortex that increases sodium and water reabsorption while promoting potassium excretion

Antidiuretic Hormone (ADH)

Promotes water reabsorption in kidney collecting ducts, decreasing urinary output to retain fluid.

Natriuretic Peptides (NP)

Promotes sodium and fluid excretion and inhibits thirst reflex to reduce overall blood volume.

Normal osmolarity range

280-295 mOsm/L

What does a elevated osmolarity state indicate? (FVD)

- dehydration which will trigger the thirst reflex

- Particles > water

What does decrease osmolarity indicate? (FVE)

- fluid overload

- water > particles

Risk factors: Age

Infants and elderly are at the highest risk for fluid imbalances.

Risk factors: Chronic Illnesses

Kidney disease, liver disease, diabetes, heart failure, and cancers.

Risk factors: Medications

Diuretics (loop, thiazides, corticosteroids), ACE inhibitors, or ARBs.

Risk factors: Diet

Poor nutrient/electrolyte intake or excessive mineral consumption.

Risk factors: Environmental

Extreme heat exposure causing heavy sweating.

Risk factors: Acute Conditions

Fever, vomiting, diarrhea, or blood loss.

Risk factors: Surgeries or Traumas

Physical trauma, burns, or surgical drains depleting fluids.

Electrolyte imbalance reflex effect

Can result in hyperactive or depressed reflexes.

Normal intake per day

2400-2700 mL

Normal output a day

- Urinary: 1400-1500 mL

- total: 2300-2600 mL (includes insensible loss)

Daily weights calculation

1L = 1kg or 2.2 lb

Infant fluid dependency

Infants rely entirely on caregivers due to limited capability to obtain fluids independently.

Infant physical assessment for fluid status

Assessment must include inspecting for sunken or bulging fontanels and eyes.

Older adult muscle mass effect on fluid balance

Decline in muscle mass reduces overall body water retention.

Older adult adipose tissue effect on body water

Increased adipose tissue holds no water, lowering overall body water proportion.

Older adult skin elasticity effect on fluid loss

Loss of skin elasticity increases insensible water losses.

Older adult GFR effect on fluid regulation

Decreased GFR reduces the kidneys' ability to concentrate urine.

Older adult adrenal gland changes

Adrenal gland atrophy impairs aldosterone function, decreasing sodium and water retention.

Older adult thirst reflex changes

Diminished thirst reflex reduces voluntary fluid intake.

Older adult fall risk factor in hyponatremia

Hyponatremia-induced muscle weakness combined with mobility limitations creates high risk for falls.

Hemodilution pathophysiology (FVE)

Excess circulating fluid volume dilutes solutes in the intravascular space.

Hemoconcentration pathophysiology (FVD)

Decreased circulating fluid volume concentrates solutes in the intravascular space.

Hemodilution: Hemoglobin & Hematocrit (H&H)

Falsely decreased.

Hemoconcentration: Hemoglobin & Hematocrit (H&H)

Elevated

Hemodilution: Serum Electrolytes

Falsely decreased (e.g., hyponatremia, hypokalemia).

Hemoconcentration: Serum Electrolytes

Often elevated.

Hemodilution: Serum Osmolarity (FVE)

Low (< 280 mOsm/L; or < 270 mOsm/L). (hypo-osmolar)

Hemoconcentration: Serum Osmolarity (FVD)

Elevated (> 295 mOsm/L). (hyperosmolar)

Hemodilution: Urine Specific Gravity

Low/normal.

Hemoconcentration: Urine Specific Gravity

Elevated.

Normal Serum Sodium

135 to 145 mEq/L; minor 1-point variance has little clinical significance.

Normal Serum Potassium

3.5 to 5.0 mEq/L; small changes cause cardiac effects requiring immediate intervention.

Low Albumin Levels consequence

Fluid leaks from intravascular to interstitial spaces, resulting in anasarca.

Rhabdomyolysis electrolyte effect

Releases intracellular electrolytes into the bloodstream, creating life-threatening hyperkalemia.

Primary Prevention

- stress management

- med safety

- heat safety

Secondary prevention

- monitoring serum blood levels

Tertiary interventions: independant

- I&Os

- Daily weights

- Limit: alcohol, caffeine, and high-octane energy drinks (cause diuresis)

- Pt education on their plan of care

Tertiary prevention: Collaborative

- Oral fluid replacement and IV fluids

- Hypodermoclysis

- Diuretics (loop) or electrolyte sups

- Education on salt sup (Warn of hyperkalemia risk if sups contain K+)

- Kayelexalate (binds to K+ in bowel to lower levels through feces)

What is hypodermoclysis? When do we use it?

The administration of fluid via subQ injection. This is used when a pt is dehydrated and lacks viable IV access

Isotonic Solutions osmolarity

Same osmolarity and particle concentration as normal body fluids (280 to 295 mOsm/L).

Isotonic Solutions examples

- Normal Saline (0.9% NS)

- Lactated Ringer's (LR)

How does D5W work?

It is isotonic in the bag but hypotonic in the body due to the sugar being "eaten" by cells

When is LR not given?

When a pt has liver disease (liver can't metabolize lactate properly)

Isotonic Solutions fluid shift

No shift across cell membranes; stays in intravascular space to expand circulating volume.

Hypotonic Solutions solute concentration

Lower solute concentration than body fluids.

Hypotonic Solutions examples

- 1/2NS (0.45)

- 1/3NS (0.33)

- 1/4NS (0.225)

- 2.5% Dextrose in water

Hypotonic Solutions fluid shift

Shifts out of intravascular space and into intracellular space (cells). Cell swells

Hypertonic Solutions osmolarity

Exceeds 300 mOsm/L; higher particle concentration than body fluids. Cell shrinks

Hypertonic Solutions examples

- D5NS

- D10

Hypertonic Solutions fluid shift

Drawn out of cells and interstitial spaces into intravascular space.

IV Fluid Rationale

Infused to restore or maintain fluid volume, rehydrate cells, or correct electrolyte imbalances.

IV Infiltration

Fluid leaks into interstitial space after cannula punctures vessel, causing cool, taut, edematous skin.

Fluid Volume Overload (IV Complication)

Excessive infusion overloads cardiovascular system, causing fluid shift into lungs or tissues.

Rapid Solute Shifts (IV Complication)

Rapid fluid shifts cause cellular swelling/shrinking, resulting in neurological damage or decreased LOC.

Isotonic Fluid Outcome

Restores intravascular volume

Isotonic fluid uses

- increases blood volume

- fainting (orthostatic hypotension or dehydration)

- blood transfusions

- Hemorrhaging trauma (given as bolus)

Isotonic fluid: Nursing considerations

- fluid overload

- hypernatremia

- hyperchloremia

Hypotonic Fluid Outcome

Cellular rehydration.

Hypotonic fluid uses

Conditions which cause cellular dehydration

- hypernatremia

- HHNS (T2DM)

- DKA (T1DM)

Hypotonic fluid: Nursing considerations

- Not for ICP pt

- Anything w/ dextrose do not give to DM pt

- Infuse slowly

- hyponatremia

- edema

- hypovolemia

Hypovolemia s/s

Increased risk in pt w/ liver disease, trauma, + burns

- tachycardia

- low BP

- cellular edema

- Cell damage

Hypertonic Fluid Outcome

Vascular expansion or solute balancing.

Hyperotonic fluid uses

- hypovolemia

- heat related illness (heat exhaustion)

- peritonitis

Hypertonic fluid: Nursing considerations

- fluid overload

- hypernatremia

- hyperchloremia

- infuse slowly

Perfusion & Fluid Balance

Deficit causes hypovolemic shock; excess stresses the heart and blood vessels.

Oxygenation & Fluid Balance

Fluid excess causes pulmonary edema; potassium imbalance weakens breathing muscles.