fluid/electrolyte imbalances

fundamentals in nursing

Hyponatremia (Na²+ < 135)

system affected: neuro

patho: low sodium in ECF→ water shifts into cells (ICF) → brain cells swell

common causes: excess water intake, SIADH, heart failure, thiazide diuretics

s&s: headache, confusion, seizures, decreased LOC, n/v

common treatments: hypertonic saline (3% NaCl), fluid restriction

⭐️ correct slowly!

hypernatremia (Na²+ >145)

system affected: neuro

patho: high sodium in ECF→ water shifts out of cells → cells shrink

common causes: dehydration, diabetes, excessive salt intake, fever, diarrhea

s&s: thirst, irritability, restlessness, seizures

common treatments: hypotonic solutions (0.45% NaCl, D5W), PO water

hypokalemia (k+ < 3.5)

system affected: cardiac, muscle

patho: low potassium→ decreased excitability of cardiac and skeletal muscle

common causes: GI losses (vomitting, diarrhea), diuretics, NG suction, alkalosis

s&s: weakness, cramps, paralytic ileus, arrhythmias, flat T waves

common treatments: PO or IV K+ replacement, ekg and tele monitoring

⭐️ Never give potassium IVP

hyperkalemia (K+ > 5.0)

system affected: cardiac, muscle

patho: high potassium → increased excitability but then conduction blocks

common causes: renal failure, potassium-sparing diuretics, ACE inhibitors, tissue breakdown (burns, trauma)

s&s: Tall T waves, bradycardia, arrhythmias, muscle weakness

common treatments: IV calcium gluconate, insulin and glucose, sodium polystyrene, dialysis

hypocalcemia ( Ca²+ < 9.0)

system affected: neuro, renal, bones

patho: low calcium → increased neuromuscular excitability

common causes: hypoparathyroidism, renal disease, low vitamin D, pancreatitis

s&s: tetany, numbness, Chvostek/ Trousseau signs, seizures

common treatments: PO/IV calcium, vitamin D, seizure precautions

hypercalcemia ( Ca ²+ > 10.5)

system affected: neuro, renal, bones

patho: high calcium → decreased excitability, increased bone resorption

common causes: hyperparathyroidism, bone metastases, prolonged immobility, excessice calcium/ vitamin D

s&s: lethargy, weakness, constipation, kidney stones, arrhythmias

common treatments: IV NS, loop diuretics, bisphosphonates

hypomagnesmia (Mg ²+ < 1.3)

system affected: neuro, cardiac

patho: low magnesium → increased excitability

common causes: alcoholism, diarrhea, malnutrition, diuretics

s&s: tremors, tetany, seizures, arrhythmias

common treatments: IV magnesium sulfate, PO Mg, seizure precautions

hypermagnesmia (Mg ²+ > 2.1)

system affected: neuro, cardiac

patho: high magnesium → decreased excitability

common causes: renal failure, excess antacids/ laxatives containinf Mg, overcorrection

s&s: flushing, hypotension, decreased reflexes, respiratory depression

common treatments: IV calcium gluconate (antagonist), dialysis, stop Mg intake

isotonic fluid deficit (hypovolemia)

system affected: vascualar/perfusion

patho: equal loss of water and sodium → decrease in ECF volume

common causes: hemorrhage, GI losses (vomitting, diarrhea), third-spacing, diuretics

s&s: dry mucous membranes, hypotension, tachycardia, decreased urine output

common treatments: isotonic fluids (0.9% NS, LR)

isotonic fluid volume excess (hypervolemia)

system affected: vascular/pulmonary

patho: excess water / sodium → increase ECF volume

common causes: heart failure, renal failure, liver cirrhosis, excess IV fluids

s&s: edema, crackles, increased BP, bounding pulses

common treatments: diuretics, fluid / salt restriction

hypotonic fluid excess (water intoxication)

system affected: neuro

patho: too much free water → ECF is hypotonic → water into cells

common causes: excessive water intake, SIADH, psychogenic polydipsia

s&s: confusion, seizures, cerebral edema

common treatments: hypertonic saline (3% NaCl), fluid restriction

hypertonic dehyration

system affected: neuro

patho: more water loss than sodium loss → ECF hypertonic → cells shrink

common causes: fever, sweating, osmotic diuresis (uncontrolled diabetes), diarrhea

s&s: thirst, confusion, seizures

common treatments: hypotonic fluids (0.45% NS, D5W)

hyperphosphatemia ( PO4- > 4.8)

system affected: neuromuscular, musculoskeletal

patho: increased phosphate→ low calcium ⭐️twitchy

common causes: Chronic kidney disease, hypoparathyroidism, cell/tissue breakdown, excess intake

s&s: arrhythmias, muscle spasms, numbness/tingling, seizures, bone/joint pain, rash/itchy skin

common treatments: treat underlying cause, phosphate binders, restrict intake, dialysis (severe)

hypophosphatemia ( PO4- < 2.5)

system affected: neuromuscular, musculoskeletal

patho: low phosphate → insufficient ATP → low energy ⭐️ weak

common causes: hypoparathyroidism, DKA, malabsorption, refeeding syndrome

s&s: confusion, muscle weakness, fatigue, bone/muscle pain, seizures, numbness, confusion/ irritability

common treatments: replacement, check calcium

Importance of fluids and electrolytes

• maintain homeostasis

• transport nutrients, electrolytes, and oxygen to cells

• remove waste

• illness or injury can disrupt homeostasis leading to an imbalance of fluids and electrolyes (often secondary to diagnosis)

body water content

• human body is made of mostly water

• accounts for 50% - 60% body weight in the adult

• water content varies with age, gender, and fat content

• preterm fetus has highest content, decreasing with age

• older adults more likely to have imbalances and dehydration

fluid comparments

intracellular fluid (ICF)

• found within cells

• approx 2/3 body water

extracellular fluid (ECF)

• found outside the cells

• approx 1/3 body water

calculation of fluid gain/loss

1 Liter of water weighs 2.2 pounds (1 Kg)

• hemodialysis: weigh before and after

• daily weights are best way to recognize fluid volume status

electrolyte composition

ICF: cation potassium, anion phosphate

ECF: cation sodium, anion chloride

simple diffusion

- movement of molecules across a permeable membrane from an area of high concentration to low concentration

-movement stops when the concentrations are equal in both areas

⭐️ sliding down a slide- no energy needed

facilitated diffusion

-requires the use of protein carrier in the cell membrane

-combines with a molecule too large to pass easily on its own

⭐️ taking a friend with you to the bathroom

active transport

-molecules move against the concentration gradient

-requires use of external energy (ATP)

• sodium - potassium pump (controls muscle movement)

⭐️ walking up a slide

osmosis

-movement of water down a concentration gradient from a region of low solute concentration to one of high solute concentration across a semipermeable membrane

-no outside energy needed

-the concentration of the solution determines the strength of osmotic pull

osmolarity vs osmolality

Osmolarity

• measure the concentration of molecules per volume of solution kg ( mOsm/L)

Osmolality

• measures the number of milliosmoles per kg (mOsm/kg) of water

• concentration of molecules per weight of water

• preferred measurement to evaluate the concentration of plasma, urine, and other body fluids (high concentration = dehydration)

hydrostatic pressure

-force of fluid in a compartment pushing against a cell membrane or vessel wall

-blood pressure generated by heart’s contraction

-at capillary level, hydrostatic pressure is the major force that pushes water out of the vascular system and into the interstitial space

oncotic pressure

-colloid osmotic pressure caused by plasma proteins (albumin)

-attract water, pulls fluid drom the tissue into the vascular space

fluid spacing

first spacing: normal distribution in ICF and ECF

second spacing: abnormal accumulation of interstitial fluid (edema)

third spacing: fluid is trapped where it is difficult or impossible for it to move back into cells or blood vessels (ascites, severe burns) →NI: force water back in

regulation of water balance

daily intake: 2000-3000ml/day

urine: 0.5-1 mL/kg/hr

Hypothalamic-Pituitary Regulation

-osmoreceptors in hypothalamus sense fluid deficit or increse

-deficit stimulates thirst and ADH release

-decreased plasma osmolality (water excess) suppresses ADH release

renal regulation

-adjusts urine volume and excretion of electrolytes

-reabsorption of water and electrolytes in the renal tubules in response to ADH, aldosterone, and other hormones

• BP regulation

adrenal cortical regulation

-releases hormones to regulate water and electrolyres

• glucocorticoids

cortisol → retention of sodium and water

• mineralcorticoids

aldosterone→ enhances sodium rentention and potassium excretion “water and sodium saving hormone”

cardiac regulation

-atrial natriuretic peptide (ANP) and b-type natriuretic peptide (BNP) hormones released in response to increased volume and high sodium levels

-natural antagonists to the RAAS system

-promotes excretion of sodium and water, decreasing blood volume and BP

GI regulation

-GI tract secretes about 8,000 mL of digestive juices/day (small intestine)

-absorbs most fluid, small amount is eliminated in feces

older adult considerations

Ideal peripheral veins

-distally located

-not over a joint

-located at a site free from bruising or poor skin integrity

-straight

-lack visible valves

-well stabilized in the connective tissue

when to avoid an extremity for IV

-AV device for dialysis

-flaccidity after stroke

-removal of axillary lymph nodes

-hx of breast cancer/mastectomy

-lymphedeme

IV gauge and uses

midline catheter

-placed in a peripheral vein of the upper arm; tip ends near axillary vein

-used with poor vein selection or IV needed longer time (2 weeks)

-Ultrasound guided

• Do Nots

-use for vesicant meds

-avoid routine, frequent blood draws

-administer incompatible meds simultaneously through double lumen

Starting an IV

-verify order

-prime tubing to prevent air embolism

-tourniquet 2-4 inches above insertion site

-remove tourniquet before flushing (use 10 cc)

-assess for complications

-secure IV to skin

-document

IV documentation

-date+ time

-who inserted

-vein/location

-type of IV cath (gauge, length)

-number of attempts

-patient tolerance

-dressing type

-status (saline lock, med infusing)

-policy on how often to document

Assessing IV site

-observe redness, swelling, bruising, edema, patency, leaking of fluid

-palpate for pain, hardness at site, temperature

-ask if it’s painful

-document findings

-determine if removal is necessary

-assess often

infiltration

→ Non-vesicant IV fluid leaks into surrounding tissue.
Signs: Cool, pale, swollen skin; discomfort; slowed/stopped infusion.
Intervention: Stop the IV, remove the catheter, elevate the extremity, and restart the IV in a different site. Apply warm/cold compress as appropriate for the solution.

extravasation

→ Vesicant medication leaks into surrounding tissue, potentially causing tissue damage/necrosis.
Signs: Burning, pain, swelling, redness, blistering, or tissue damage.
Intervention: STOP the infusion immediately. Do NOT flush. Leave the catheter in place initially to aspirate remaining medication if indicated, then follow the medication-specific extravasation protocol. Notify the provider/pharmacy.

⭐ Remember: Extravasation = STOP + DON'T FLUSH

phlebitis

→ Inflammation of the vein, often from catheter irritation or medication.
Signs: Redness, warmth, tenderness, pain, and a hard/cord-like vein.
Intervention: Stop the infusion and remove the IV. Apply a warm compress as appropriate and restart at a different site if IV therapy is still needed.

thrombophlebitis

→ Inflammation of the vein + blood clot.
Signs: Pain, redness, warmth, swelling, and a firm/cord-like vein.
Intervention: Stop the infusion and remove the IV. Notify the provider; assess for worsening symptoms and follow orders for treatment of the thrombus.

hematoma

→ Blood leaks into surrounding tissue because the vein was punctured or damaged.
Signs: Bruising, discoloration, swelling, and tenderness.
Intervention: Stop the infusion and remove the IV. Apply pressure to the site; use a cold compress initially to reduce bleeding/swelling.

air embolism

→ Air enters the bloodstream and interferes with circulation.
Signs: Sudden dyspnea, chest pain, coughing, confusion, hypotension, or loss of consciousness.
Intervention: Stop the infusion and clamp the line. Place the patient on their left side with the head lowered as directed by protocol, administer oxygen, and notify the provider/rapid response.

IV site infection

→ Microorganisms enter through the IV site, potentially causing local or systemic infection.
Signs: Redness, warmth, swelling, tenderness, drainage, fever, or chills.
Intervention: Stop/remove the IV, notify the provider, and monitor vital signs. Cultures and antibiotics may be ordered.

Catheter related bloodstream infection (CRBSI)

→ A bloodstream infection caused by an IV catheter. This is more serious than a local IV-site infection because the infection has entered the bloodstream.
Signs: Fever, chills, hypotension, tachycardia, redness/drainage at the catheter site, and possible sepsis.
Intervention: Stop/remove the catheter as ordered, notify the provider, obtain blood cultures as ordered, monitor for sepsis, and administer prescribed antibiotics.

⭐ Remember: CRBSI = catheter + bloodstream infection

thrombosis

→ A blood clot forms inside the vein, often due to irritation or damage from the IV catheter.
Signs: Pain, swelling, redness, warmth, and a firm/cord-like vein.
Intervention: Stop the infusion and remove the IV. Notify the provider, assess the extremity, and monitor for complications such as embolism. Treatment may include anticoagulation if prescribed.

⭐ Remember: Thrombosis = clot

venous spasm

→ The vein suddenly contracts or spasms, often in response to irritation from the catheter, medication, or a cold solution.
Signs: Sudden pain, discomfort, resistance when flushing, slowed/stopped IV flow, and the vein may feel tight.
Intervention: Stop the infusion, check the IV site, and assess for infiltration or phlebitis. A warm compress may help relax the vein. Restart the IV at a different site if needed.

⭐ Remember: Spasm = vein tightens → IV won't flow

nerve damage

→ The catheter or needle injures or irritates a nearby nerve.
Signs: Sharp/electric or burning pain, numbness, tingling, weakness, or pain that radiates along the limb.
Intervention: Stop the procedure/infusion immediately and remove the catheter. Assess sensation and movement, notify the provider if symptoms persist, and document the findings.

⭐ Remember: Electric/shooting pain or numbness = think nerve damage

lumen occlusion

→ The IV catheter becomes blocked, preventing fluid or medication from flowing through the lumen.

Signs:

• IV will not flush

• Resistance when flushing

• Infusion slows or stops

• Pump may alarm for occlusion

• No blood return (depending on catheter type)

Common causes:

• Blood clot in the catheter

• Medication precipitate

• Catheter kinked or positioned incorrectly

Intervention:
→ STOP the infusion and check for mechanical problems (kinks, clamps, positioning).
→ Do NOT forcefully flush because this can damage the catheter or dislodge a clot.
→ If mechanical causes are ruled out, follow facility protocol for an approved catheter-clearing solution (such as a thrombolytic for a clot-related occlusion) and notify the appropriate clinician.

isotonic solutions

What is it?
→ Has a similar osmolarity to blood/plasma, so water stays mostly in the extracellular space rather than causing major fluid shifts into or out of cells.

Main purpose:
→ Expand intravascular volume and increase circulating fluid.

Common examples:

• 0.9% Normal Saline (NS)

• Lactated Ringer's (LR)

• D5W ⭐ technically isotonic in the bag, but acts hypotonic after glucose is metabolized

When used:

• Hypovolemia/dehydration

• Blood loss

• Burns

• Hypotension

• Fluid resuscitation

• Perioperative fluid replacement

Careful considerations:

• Too much → fluid overload

• Monitor for edema, crackles, dyspnea, increased BP

• Use caution in heart failure and renal impairment

🧠 Remember:

ISO = same → stays in the bloodstream

hypotonic solutions

What is it?
→ Has a lower osmolarity than blood, so water moves from the extracellular space into cells.

Main purpose:
→ Hydrate cells.

Common examples:

• 0.45% NS (½ NS)

• 0.225% NS (¼ NS)

• D5W (acts hypotonic after metabolism)

When used:

• Hypernatremia (high Na⁺)

• Cellular dehydration

• Patients who need free water replacement

Careful considerations: ⚠

• Can cause cellular swelling

• Avoid/use extreme caution with increased ICP or brain injury → cerebral edema can worsen

• Can worsen hypotension because fluid leaves the vascular space

• Monitor sodium and neurologic status

• avoid in trauma/burn victims

🧠 Remember:

HYPO = water goes IN → into the cells

hypertonic solutions

What is it?
→ Has a higher osmolarity than blood, so it pulls water out of cells and into the extracellular/intravascular space.

Main purpose:
→ Increase intravascular volume and pull excess water out of swollen cells.

Common examples:

• 3% NS

• 5% NS

• D5NS

• D5½NS

• D10W

When used:

• Severe symptomatic hyponatremia

• Cerebral edema/increased ICP (particularly hypertonic saline)

• Significant cellular dehydration in specific situations

Careful considerations: ⚠⚠

• Can cause fluid overload

• Can cause hypernatremia

• Monitor sodium closely

• Monitor neurologic status

• Hypertonic saline is often given through a central line depending on concentration/protocol

• Correcting sodium too quickly can cause serious neurologic injury

🧠 Remember:

HYPER = pulls water OUT of cells → into the bloodstream

IV additives

What are IV additives?

→ Medications, electrolytes, vitamins, or other substances added to IV fluids to treat or prevent a specific problem.

Examples:

• Potassium (KCl)

• Magnesium

• Calcium

• Sodium bicarbonate

• Antibiotics

• Vitamins

colloids

What are colloids?

→ IV fluids containing large molecules (usually proteins) that stay in the bloodstream and pull water into the intravascular space.

Main purpose:
→ Increase blood volume/intravascular pressure.

Examples

• Albumin ⭐

• Dextran

• Hydroxyethyl starch (less commonly used due to safety concerns)

When are they used?

• Hypovolemia when increased intravascular volume is needed

• Severe fluid loss in certain situations

• Low albumin / selected patients needing oncotic support

How do they work?

Think: Colloids = pull fluid INTO the bloodstream

Their larger particles remain in the vascular space longer than crystalloids, increasing colloid oncotic pressure.

⚠ Nursing Considerations

• Monitor for fluid overload

• Monitor BP, HR, lung sounds, edema, and I&O

• Use caution with heart failure or renal impairment

• Monitor for allergic reactions, particularly with some colloid products

• Albumin may be used to increase oncotic pressure in specific clinical situations.

IV meds

-have a rapid therapeutic effect but can have adverse reactions

• RN must know:

-indications, dosage, contraindications, precautions, dilution, rate of infusion, potential vesicant/irritant, necessary pt monitoring with med