fluids and electrolytes

NRS 400

what are the different fluid compartments

The different fluid compartments in the body include intracellular fluid (ICF), which is found within cells, and extracellular fluid (ECF), which includes interstitial fluid (surrounding cells) and plasma (within blood vessels). Together, these compartments maintain fluid balance and homeostasis.

how does fluid move

between compartments through osmosis and diffusion, driven by gradients in concentration and pressure.

where do we need fluid to be

in various body compartments for proper function, including intracellular and extracellular spaces most importantly intravascular

fluids in high acuity

the key becomes not just where fluid exists, but where it needs to be sustain life and maintain organ function. In high acuity settings, monitoring and managing fluid distribution is critical for patient outcomes.

intravascular volume is a critical component for

perfusion to the brain, heart, and kidneys

fluid balance

tends to help you recognize early perfusion changes

early nursing indicators to watch

urine output trends, mental status changes, skin/temperature/ moisture/cap refill, subtle blood pressure changes

IV fluids in critical care

have specific indications, contradictions, and adverse effects

fluids can directly affect

cellular integrity, neurological function, pulmonary status, and cardiovascular stability

hypotonic fluids

cell swelling (0.45 sodium chloride)

hypotonic fluids high acuity concern

increased ICP, worsening cerebral edema, not used in neuro/trauma patients, high risk seizures, DKA, (would kill head injuries)

isotonic fluids

volume without shifts (0.9% sodium chloride)

Isotonic fluids high acuity concern

first-line in shock/trauma, can. worsen pulmonary edema, chloride load → metabolic acidosis, fluid overload, and caution with heart failure

hypertonic fluids

cell shrinking (5% dextrose in water, 3.5% sodium chloride)

hypertonic fluids high acuity concern

ICP management, severe hyponatremia (most common), central line considerations, rapid sodium shifts = demyelination risk (seizure risk), vesicant → IV med that can destroy tissue very easily, not a maintenance fluid is a rescue drug,

colloids

albumin

colloids in high acuity concern

shock, burns, hypoalbuminemia with third spacing

electrolytes in high acuity

abnormal electrolytes often precede deterioration even when vitals look stable

potassium (3.5-5.0)

arrhythmia risk, primarily intracellular, small serum shifts can trigger life-threatening dysrhythmias, assess renal function before supplementation, watch for ECG changes, muscle weakness, and overall instability, prioritize K+

sodium (135-145)

think water balance and volume status, rapid shifts can cause cerebral edema or osmotic demyelination, correction speed matters, key assessment → mental status, urgency, fluid choice, and neurological safety

magnesium (1.6-2.2)

Low torsades de pointes, stuck with potassium, low Mg can prevent potassium repletion

Calcium (9.0-10.5)

calcium drives contraction and perfusion, Ca supports muscle squeeze and rhythm stability

track what

patterns