MNT I Fluid & Electrolytes

What primarily makes up intracellular fluid?

potassium and phosphate

What primarily makes up extracellular fluid?

sodium, chloride, bicarb

osmosis

movement of water freely

Filtration

movement of water and solutes

hydrostatic pressure (push)

pressure from fluid pushing against a surface, high to low concentration

What pressures work together to influence the movement of water and solutes?

osmotic and hydrostatic

Osmotic pressure (pull)

pulls fluid from low concentrations of solutes to high concentration of solutes

Thirst mechanism

sensors in interstitial fluid recognize changes in fluid, hypothalamus detects need for more water, thirst sensation increases

What organ excretes/retains sodium and water

kidneys

What hormones are related to fluid and electrolytes?

RAAS, ADH, and ANP

ADH

works to retain water

ANP (atrial natriuretic peptide)

excretes sodium and water (reduces)

When increased fluid is moving through the kidneys

BV increases, hydrostatic pressure increases, fluid moves from capillaries to renal tubules, fluid is excreted as urine

RAAS (renin-angiotensin-aldosterone system)

hormonal pathway to detect decreased BV and bring it back to normal range

What should be considered fluid intake?

water, juice, coffee, tea, milkshakes, smoothies, ice cream, soups,

Sensible losses

visible and measurable fluid losses (urine and feces)

Insensible losses

fluid losses not usually seen or measured (respiration, sweat)

hypovolemia

dehydration, too low BV, insufficient fluid circulating throughout the body

Causes of hypovolemia

vomiting, diarrhea, excessive sweating, poor PO

hypervolemia

too high BV, excessive fluid

Causes of hypervolemia

decreased urinary output or compromised fluid regulation

Signs / symptoms of hypervolemia

weight gain, edema, ascites, elevated BP

signs / symptoms of hypovolemia

dry mouth, poor skin turgor, elevated BUN/Cr, decreased moisture in oral cavity

What specific chronic diseases relate to fluid and electrolyte balance?

CKD, heart failure, and liver cirrhosis

chronic kidney disease (CKD)

insufficient renal function; Na and water are retained because kidneys can’t filter

heart failure

insufficient blood flow due to reduced cardiac output; body perceives low BV and increases fluid retention

liver cirrhosis

failed fluid circulation, fluid moves into third spaces

1 liter of fluid loss equals

2 lbs

mild fluid volume deficit or excess

2% loss/gain

moderate fluid volume deficit or excess

5% loss/gain

severe fluid volume deficit or excess

8% loss/gain

hyponatremia

too low sodium

hypernatremia

excessive sodium

hypokalemia

too low potassium

hyperkalemia

excessive potassium

Electrolyte labs include

Na, K+, Cl, Ca, phos, Mg

Third spaces/spacing

fluid accumulation in spaces between organs, caused by illness or injury

What spaces don’t contribute to typical circulation of fluids?

peritoneal, pericardial, thoracic

Patients with dehydration and severe electrolyte abnormalities may experience

confusion, fatigue, dry mouth, dizziness/nausea

When is fluid restriction indicated?

individualized care is recommended, severe heart failure with hyponatremia or congestion, or if sodium restriction + diuretic use isn’t helping with fluid retention

Typical fluid restriction amount

1.5-2 L fluid

When should restrictive diets be avoided?

if poor appetite or inadequate oral intake are present

Once PO intake is improved and meeting __ % of needs, then consider diet restriction if indicated

75

fluid & electrolyte assessment

medications, labs, weight, NFPE, nutrition information

What medications should you assess for?

ACE inhibitors and diuretics

What labs should you assess for?

albumin, BUN, sodium (ABS), electrolytes, Cr, GFR

What should you assess in the NFPE?

edema

What should you assess in diet / nutrition information?

fluid intake and sources of electrolytes

common diagnoses for fluid & electrolyte imbalances

altered nutrient related labs, food & nutrition knowledge deficit, unintentional weight gain, inadequate or excessive fluid intake

common interventions for fluid & electrolyte imbalances

nutrition education, adjusting free water flushes or EN formula, IVF changes, daily weigh ins

monitoring / evaluation for fluid & electrolyte imbalances

stable dry weight, fluid-related labs, electrolyte levels, compliance with fluid restricted diet if indicated