IV solutions from the nursing side
- Fundamental
Isotonic solutions stay in the vessels, hypotonic ones move into cells, and hypertonic ones draw water out of cells.
What it is
Nurses do not choose the solution, but they must know what each one does in order to monitor the patient. A solution is defined by its tonicity compared with plasma: an isotonic solution does not move water between vessels and cells; a hypotonic one moves it into cells; a hypertonic one draws it out. Each group has its own uses and risks. This page covers the nursing view; the physiology is on the tonicity page.
Key points
- Tonicity compares the particle concentration of the solution with that of plasma.
- Isotonic: water stays where it is; it expands the volume inside the vessels.
- Hypotonic: water moves into the cells.
- Hypertonic: water moves out of the cells into the vessels.
- Kidney patients and small children usually need smaller volumes.
Components
- Isotonic: 0.9 % saline, lactated Ringer's, 5 % dextrose in water (in the bag).
- Hypotonic: 0.45 % saline; 5 % dextrose in water once metabolised.
- Hypertonic: 3 % saline, 5 % dextrose with 0.45 % saline, 5 % dextrose with lactated Ringer's.
What it is for
- 0.9 % saline: haemorrhage, severe vomiting or diarrhoea, tube losses, drains, mild hyponatraemia and transfusions.
- Lactated Ringer's: resuscitation, gastrointestinal losses, burns, trauma, metabolic acidosis and surgery.
- 5 % dextrose in water: free water, hypernatraemia and a glucose supply.
- Hypotonic: intracellular dehydration and hypernatraemia.
- Hypertonic: severe hyponatraemia and cerebral oedema, in critical-care settings.
What to watch with each type of solution
| Type | Examples | Effect | What the nurse watches |
|---|---|---|---|
| Isotonic | 0.9 % saline, lactated Ringer's | Expands volume in the vessels | Overload: breathlessness, crackles, oedema, high blood pressure; more in heart or kidney failure |
| Isotonic that becomes hypotonic | 5 % dextrose in water | Supplies free water | Not for resuscitation; watch for cerebral oedema and blood glucose |
| Hypotonic | 0.45 % saline | Moves water into cells | Hypotension, confusion, cerebral oedema; avoid in liver disease, trauma and burns |
| Hypertonic | 3 % saline | Draws water out of cells | Serum sodium, overload, breathing difficulty; avoid in heart or kidney failure |
In nursing practice
- Watch skin turgor, urine output, lung sounds, oxygen needs and new oedema.
- Lactated Ringer's is not used if serum pH is above 7.5 and may raise potassium in kidney failure.
- In a fasting patient, fluids may start faster and are reduced as oral intake resumes.
- With gravity infusions, keep the drip chamber a quarter to half full.
- Review the need for fluids with the provider regularly.
Common mistakes
- Thinking 5 % dextrose in water replaces volume like 0.9 % saline.
- Not watching for overload in older adults or in heart or kidney failure.
- Connecting a secondary infusion without checking compatibility: a precipitate can form.
- Not checking the drop factor of the set before calculating a gravity drip rate.
Test yourself
Think of the answer, then tap the question to see it.
Why is 5 % dextrose in water not used to resuscitate a patient in shock?
Because once the glucose is metabolised, free water is left that moves into cells: it does not stay in the vessels and can cause cerebral oedema.
Which complication is watched for above all with isotonic solutions?
Volume overload: breathlessness, crackles, oedema and rising blood pressure, especially in heart or kidney failure.
In which patients are hypotonic solutions avoided?
In patients with liver disease, trauma or burns, and when cerebral oedema is a concern, because they move water into the cells.
Elsewhere in DurgiPedia
Connections
Educational content for students; it does not replace your institution's protocols, supervised clinical training or a prescriber's order. Dose-calculation examples use made-up numbers: they are educational, not a clinical order.
Sources: Nursing Fundamentals, 15.3 Intravenous Solutions (Open RN (Chippewa Valley Technical College), LibreTexts, 2021); Nursing Skills, 23.2 IV Therapy Basics (Open RN (Chippewa Valley Technical College), LibreTexts, 2021).
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