IV fluids are drugs: each has an indication, a dose, and adverse effects. Their effect depends on tonicity — the effective osmolality compared with plasma (normal serum osmolality 275–295 mOsm/kg) — which decides whether water moves into cells, out of cells, or stays outside them.

Balanced crystalloids (lactated Ringer's, Plasma-Lyte) contain less chloride than 0.9% saline; large volumes of 0.9% saline can cause hyperchloremic metabolic acidosis. Balanced crystalloids are suggested for many critically ill adults, including sepsis.

Electrolyte replacement restores specific ions. Normal adult values:

Hyperkalemia drugs (emergency sequence): (1) calcium gluconate stabilizes the heart when ECG changes are present; (2) regular insulin IV with dextrose and inhaled albuterol/salbutamol shift potassium into cells; sodium bicarbonate only with metabolic acidosis; (3) remove potassium — sodium zirconium cyclosilicate or patiromer (binders), loop diuretics if the kidneys respond, hemodialysis. Sodium polystyrene sulfonate is less favored (rare intestinal necrosis).

Maintenance fluids: adults commonly need about 25–30 mL/kg/day of water; children are calculated by weight (Holliday–Segar 4-2-1 rule) and now receive isotonic maintenance fluids with dextrose to prevent hospital-acquired hyponatremia.

• Hypotonic fluids: increased intracranial pressure, head injury, stroke, burns, trauma — risk of cerebral edema.
• Lactated Ringer's: severe liver failure (cannot convert lactate), often avoided by habit in severe hyperkalemia, although its potassium content is small and it does not raise K⁺ more than 0.9% saline, same line as blood or with ceftriaxone in neonates (calcium).
• Isotonic volume in heart failure and kidney failure: small boluses, frequent reassessment.
• Potassium: do not give (or confirm with provider first) when urine output is inadequate (below about 0.5 mL/kg/h), in hyperkalemia, severe kidney failure, or untreated Addison disease.
• Drugs that raise potassium — add caution with replacement: ACE inhibitors, ARBs, ARNI, spironolactone/eplerenone, trimethoprim, heparin, potassium-containing salt substitutes.
• Drugs that lower potassium: loop and thiazide diuretics, insulin, beta-agonists, corticosteroids, amphotericin B.
• Hypomagnesemia makes hypokalemia resistant to treatment — correct magnesium too.
• Calcium: increases digoxin toxicity risk (give slowly with ECG monitoring in clients on digoxin); never mix with sodium bicarbonate or phosphate in the same line (precipitates); ceftriaxone precipitates with calcium in neonates.
• Magnesium sulfate: caution in kidney impairment (magnesium accumulates), myasthenia gravis, heart block; enhances neuromuscular blockers.
• Sodium correction limits: raise sodium no more than 8–10 mEq/L in 24 hours (8 or less in high-risk clients); lower chronic high sodium by no more than about 10 mEq/L (mmol/L) in 24 hours.

1. Assess fluid status before and during infusion: vital signs, lung sounds, JVD, edema, daily weight (1 kg ≈ 1 L of fluid), strict intake and output, urine output (at least 0.5 mL/kg/h in adults), mental status.
2. Laboratory monitoring: sodium, potassium, chloride, glucose, BUN/creatinine, magnesium, calcium; sodium every 2–4 hours during active hyponatremia correction or per protocol; report a rise faster than ordered.
3. IV potassium safety (high-alert):
   • Never IV push or IM; always diluted, by infusion pump, preferably a premixed bag
   • Common peripheral maximum 10 mEq/h (peripheral concentration commonly ≤ 40 mEq/L); higher rates (usually ≤ 20 mEq/h) only through a central line with continuous ECG per protocol
   • Confirm adequate urine output first
   • Never add potassium to a hanging IV bag (poor mixing → concentrated bolus)
   • Check the site often; the infusion burns — slow the rate per protocol and report pain; stop for infiltration
   • Recheck potassium after replacement (about 10 mEq raises serum potassium by roughly 0.1 mEq/L — an estimate only)
4. Oral potassium: give with food and a full glass of water or juice; dilute powders and liquids; do not crush extended-release tablets.
5. Calcium gluconate IV: give slowly (e.g., 1 g (10 mL of 10%) over about 5–10 minutes for hyperkalemia or tetany) with ECG monitoring; check the site; separate lines from bicarbonate and phosphate.
6. Magnesium sulfate IV: infusion pump; before and during infusion check deep tendon reflexes (present), respiratory rate (commonly ≥ 12/min), and urine output (commonly ≥ 30 mL/h); keep calcium gluconate at the bedside as the antidote. For torsades: 1–2 g IV over several minutes (faster in arrest).
7. 3% saline: pump, second-nurse check, frequent neurologic checks, sodium monitoring, often central line (peripheral use per protocol).
8. Hyperkalemia treatment: continuous ECG; after insulin–dextrose, check glucose hourly for several hours (hypoglycemia).
9. Children and older adults: use pumps or volume-control sets to prevent accidental overload; calculate maintenance by weight.

• Explain the purpose of IV fluids and report shortness of breath, cough, swelling, or tightness in the chest during infusion
• Report burning, pain, swelling, or coolness at the IV site — especially during potassium or calcium infusions
• Oral potassium: take with meals and a full glass of fluid; do not crush or chew extended-release tablets; report abdominal pain, black stools, or vomiting
• Know signs of low potassium (muscle weakness, leg cramps, palpitations) and high potassium (weakness, numbness, irregular heartbeat)
• Do not use salt substitutes (potassium chloride) with potassium-sparing drugs or kidney disease unless the provider approves
• Diuretic users: eat potassium-rich foods if advised (bananas, oranges, potatoes, tomatoes, legumes) and keep laboratory appointments
• Oral rehydration solution is preferred for mild–moderate dehydration from diarrhea when the client can drink

Air embolism and infection are device-related risks covered in Fundamentals of Nursing (peripheral IV therapy, central venous access devices).

• Isotonic (0.9% NaCl, LR) → expands extracellular volume; hypotonic (0.45% NaCl, D5W after metabolism) → into cells; hypertonic (3% NaCl) → out of cells
• D5W is not a volume expander; hypotonic fluids are avoided in raised ICP
• Only 0.9% NaCl with blood; LR contains calcium
• IV potassium: never IV push, diluted, by pump, ≤ 10 mEq/h peripherally, check urine output first, never add to a hanging bag
• Hyperkalemia: calcium gluconate first (stabilize) → insulin + dextrose (shift) → remove; check glucose hourly
• Correct low magnesium to fix resistant low potassium
• Magnesium sulfate: check DTRs, respirations, urine output; antidote calcium gluconate
• Calcium: slow IV with ECG; raises digoxin toxicity risk; chloride = central line
• Sodium correction ≤ 8–10 mEq/L in 24 h — too fast causes osmotic demyelination
• Large volumes of 0.9% saline → hyperchloremic metabolic acidosis; balanced crystalloids preferred in many critically ill adults