Fluid and Electrolytes pt.1

What is fluid and electrolyte balance

Balance of ICV (inside the cell) and ECF (interstitial space and intravascular fluids)

Measurable amounts (and their form of outputs)

Oral → Urine

Parental → Emesis

Enemas → Feces

Irrigation → Drainage from body cavities

Non measurable amounts/Insensible (and their forms of output)

Solid foods → Perspiration

Metabolism → Vaporization through the lungs

Min amount of daily fluid intake

2300 mL

Min amount of urine output per day

400-600 mL

Min amount of output per day for insensible (non-measurable) intakes

500-1000 mL

Where does calcium MAINLY get absorbed in

Duodenum (w/the help of vit D)

Where does magnesium (Mg) MAINLY get absorbed in

Terminal end of Ileum (but depends on epithelial cell status)

What is considered intracellular

Whatever is INSIDE the cell

Common solutes: Oxygen, glucose, and electrolytes

Electrolytes:

• Cations: Potassium and Magnesium (K & Mg)

• Anions: Phosphate and Sulfate

What is considered extracellular

Anything OUTSIDE the cell

Two compartments:

• Interstitial (surrounding cell) → 75%

• Intravascular (plasma) → 20%

  • Transcellular (e.g. lymph) → 5%

Principle electrolytes: Sodium, Chloride, and Bicarbonate

Importance of intracellular fluid

Vital to cell function

• Contributes to 40% of all body weight

• Makes up 2/3 of overall body fluid makeup

3 processes that control fluid and electrolyte balance

• Osmosis

• Diffusion

• Filtration (coupled w/hydrostatic pressure)

What is osmosis

Movement of WATER

• Moves where there are more solutes due to Osmotic pressure (pressure pushing water)

• Water moves from high to low concentration of H2O

Importance of extracellular fluid

Transport system to and from cells

• Contributes a 20% of all body weight

• Makes up ½ of overall body fluid makeup

Diffusion

Movement of SOLUTES

• Move from high to low concentrations

• May use ACTIVE TRANSPORT

  • Movement of particles against concentration via alternating systems)

Filtration

Movement of fluid or water through a cell/blood vessel membrane BECAUSE of HYDROSTATIC PRESSURE

Hydrostatic pressure

• Higher on arterial side (high hydrostatic pressure inside the artery, pushing fluids and solutes out by pressure)

• Low on venous side (low hydrostatic pressure inside vein causes the high hydrostatic pressure from interstitial fluid to push fluids and solutes like waste inside the veins)

• Colloid osmotic pressure (constant pressure)

Osmolality vs Tonicity

Osmolality: Concentration of ALL solutes

Tonicity: Osmolality of solution (concentration of solutes of a solution and its effect on cell water movement)

• OSMOLALITY → “how concentrated is this fluid”

• TONICITY → “will the cell shrink, swell, or stay the same”

Isotonic fluid

Normal Saline 0.9% sodium and no cellular shifts

Hypertonic

High Osmolality

• 3% sodium

• Pulls fluid OUT into VASCULAR

• Increases EXTRACELLULAR

“If a hypertonic IV solution enters the vessels, intravascular (ECF) gets highly concentrated. Water moves outside from blood cells into intravascular space or outside cells, increasing extracellular fluid”

Hypotonic

Low Osmolality

• 0.45%, 0.33%

• Pushes fluid INTO CELLS

• Increases INTRACELLULAR

“If a hypotonic IV solution enters the vessels, the intravascular (ECF) concentration lowers or dilutes, causing water to follow INSIDE THE CELLS which are more concentrated in comparison, INCREASING INTRACELLULAR FLUID”

Osmotic pressure

Power of a solution to draw/move water across a semipermeable membrane

Hypotonic risks

Can cause swelling and rupture of cells

Hypertonic risks

Can cause dehydration & shrinkage of cells

What is responsibility of the nurse?

To know the COMPATIBILITY PROPERTIES of each medication

• Precipitation may occur which OCCLUDES the IV tubing

Where does potassium live

Inside the cell. It is the primary electrolyte in intracellular fluid components.

Where does sodium live

Outside the cell. It is the primary electrolyte in extracellular components.

Where does Calcium live

In the bones, some in the ECF, but mainly the bones

Where does magnesium live

Inside the cell and partially in the bones

Why does the ECF have more sodium than the ICF

The selective permeability of the cell membrane calls for the use of active transport or transport systems that can help pump out the extra sodium particles inside the cell towards the outside where they belong, keeping the normal balance equal.

Why does glucose need insulin

It needs insulin to bind to insulin receptors so that glucose can pass through the semi permeable membrane and be metabolized and used as energy source.

Decrease in volume of ECF

• Hypothalamic thirst center activates

• Sensation of thirst occurs

• Water is absorbed

• Increase volume of ECF

Increase osmolality of ECF

• Decreased saliva secretion

• Dry mouth

• Sensation of thirst

• Water is absorbed

• Decrease osmolality of extracellular fluid (bc water dilutes it)

Increase blood Osmolality

FLUID VOLUME DEFICIT

• Osmoreceptors in hypothalamus stimulates posterior pituitary

• ADH is released

• ADH increases distal tubule permeability

• Increases reabsorption of H2O into blood (water retained)

• Decreases urine output (decrease blood Osmolality as water dilutes body fluids)

Decreased blood Osmolality

FLUID VOLUME EXCESS

• ADH is suppressed

• ADH abscence makes distal tubules become less permeable to water

• Decrease resorption of H2O into blood

• Urine output increases (serum Osmolality returns to normal)

ADH (anti diuretic hormone)

Increases water reabsorption

Decreases urine output

Diuretic

Decreases water retention

Increases urine

ANP+BNP

FROM THE HEART

• Promotes sodium wasting, acting as a diuretic (less retention, more urine output)

• Used by the heart in response to EXCESS blood volume (fluid) and stretching cardiac walls

Renting-angiotension-aldosterone system

Causes vasoconstriction or volume retention as it produces aldosterone

ADH/ALDOSTERONE VS ANP/BNP

ADH/Aldosterone

• water retention (used in low blood Osmolality)

ANP/BNP

• Water wasting when low (used in high blood Osmolality)

Isotonic imbalances

Water & electrolytes are lost/gained in equal amounts so that Osmolality of body fluids remains constant

Osmolar imbalances

ONLY WATER is gained/loss so that Osmolality of the serum is altered.

Isotonic (isonatremic) FVD

Fluid loss not balanced by intake

• common in hemorrhage, polyuria, V/D, and chron’s

Hypotonic (hyponatremic) dehydration

More loss of sodium than water

• common in heat stroke/exhaustion causing excessive sweating

Hypertonic (hypernatremic) dehydration

More water is loss than sodium

• causes confusion, dementia, decreased intake, and ability

Fluid volume deficit

Decrease in interstitial, intravascular, or intracellular fluid (Acute or chronic)

Can be excessive or insufficient

Fluid volume deficit (excessive fluid loss)

Hemorrhage, GI suctioning, intestinal fistulas, vomit, diarrhea, renal disease, endocrine issues, abuse of laxatives, heat

Fluid volume deficit (insufficient intake)

Lack of fluid access, oral trauma, swallowing difficulty altered thirst mechanisms, confusion, and mobility issues.

Urinary in fluid volume DEFICIT

Decrease urine output

Oliguria (scant, in severe FVD)

Increased urine specific gravity (bc there’s decreased urine output thus more urine in the system)

Blood Osmolality increases (because of lack of urine draining electrolytes too’

Musculoskeletal in fluid volume DEFICIT

Fatigue

Neurologic in fluid volume DEFICIT

Altered mental status

Anxiety

Restlessness

Diminished alertness/cognition

possible coma (SEVERE FVD)

Neurologic in fluid volume DEFICIT

Altered mental status

Anxiety

Restlessness

Diminished alertness/cognition

possible coma (SEVERE FVD)

Intergumentary in fluid volume DEFICIT

Diminished turgor

Dry skin

Pale, cool extremities (blood/heat gets shunt to the core to protect organs)

Cardiovascular in fluid volume DEFICIT

Tachycardia

Orthostatic hypotension (moderate FVD)

Falling systolic/diastolic pressure (severe FVD)

FLAT NECK VEINS

Low venous filling

Low pulse volume

Low capillary refill

High hematocrit

Potential complications of clinical manifestation in the cardiovascular system

Hypovolemic shock

Metabolic process in fluid volume DEFICIT

Low body temp (isotonic FVD)

High body temp (dehydration)

Thirst

Weight loss

• 2-5% mild FVD

• 6-9% Moderate FVD

• +10% severe FDV

Fluid volume excess

ECF volume excess:

• Too much fluid in the extracellular compartments due to sodium/water retaining

• Could be due to high sodium foods, meds, or IV fluids

Cardiovascular manifestation in FVE

Circulatory overload (heart failure symptoms)

Full, bounding pulse

Increased central venous pressure (bc hydrostatic pressure is greater in the vessels or intravascularly)

Distended (bulging) neck or distended peripheral veins

Respiratory manifestation in FVE

Cough

Dyspnea (SOB)

Orthopnea (SOB when lying)

Crackles (fluid inside lungs)

Urinary manifestation in FVE

Polyuria

GI manifestation in FVE

Ascites (fluid built up in the abdomen)

Integumentary manifestation of FVE

Peripheral edema

Anasarca (swelling of the whole body)

Lab manifestation of FVE

Decreased hematocrit and BUN bc they get diluted

Weight gain= + 5% body weight

Cognitive manifestation of FVE

Altered mental status and anxiety

What is indicated in a pt w/FVE

Record I&Os

Weight daily

Reposition every 2 hours

Monitor VS, LOC, and LABS

What is indicated in a patient w/FVD

Reposition every 2 hours

Weight daily

Monitor I&Os

Monitor VS, LOC, and LABS

Teach about Orthostatic hypotension

Pharmacology therapy for FVE

Diuretics:

• Loop diuretics (lasix)

• Thiazide-type diuretics (HCTZ)

• Potassium-sparing diuretics (aldactone/spironolactase)

Loop diuretics and thiazide-type diuretics

Gets rid of excess fluid as patients use the bathroom a lot!

• Electrolytes may be pushed out, calling for electrolyte replacement

• Potassium is the electrolyte most affected

• PATIENT MAY BE AT RISK FOR HYPOKALEMIA!

• Both expel potassium, water, and sodium

Potassium-sparing diuretics

Gets rid of excess fluid as patients use the bathroom a lot!

• Electrolytes may be pushed out, calling for electrolyte replacement

• PATIENT MAY BE AT RISK FOR HYPERKALEMIA!

• Both expel ONLY water and sodium, potassium remains concentrated

Fluid management for FVE

Restrict fluids and food high in fluids

• CITRUS FRUITS

• SOUPS

• WATERMELON

Dietary management for FVE

Have them in a low-sodium diet (includes salt substitutes)

• REMEMBER: WHERE SODIUM GOES WATER FOLLOWS