INTRAVENOUS FLUIDS

Adil Abbasi, MD

Indications (where and why they are used)
Adverse effects (risks, complications)
Other key variables (tonicity, special considerations, unique features)
Tables for at-a-glance comparison
Bullet summaries for clarity
References at the end

Overview of IV Fluids: Classification:

Crystalloids

Isotonic: NS, LR, D5W (technically isotonic but acts hypotonic)
Hypotonic: 0.45% NS, D5W (after metabolism of dextrose)
Hypertonic: D5NS, D5 0.45NS, 3% NS (not commonly used except in specific situations)

Colloids

Albumin: Available as 5% or 25%, increases oncotic pressure

Normal Saline (0.9% Sodium Chloride, NS)

Indications:

Hypovolemia (shock, dehydration)
Hyponatremia
Resuscitation during hemorrhage or trauma
Fluid replacement in diabetic ketoacidosis (DKA)
Used to flush IV lines or as a carrier fluid for medications

Adverse Effects:

Hyperchloremic metabolic acidosis (due to high chloride load)
Volume overload/pulmonary edema in susceptible patients (heart failure, renal failure)
Risk of hypernatremia with prolonged or large-volume use

Other Key Features:

Isotonic (308 m Osm/L), pH ~5.5
No calories
Does not contain potassium, calcium, or buffer

Lactated Ringer’s (LR)

Indications:

Hypovolemia due to burns, trauma, or surgery
Fluid resuscitation in acidosis (except lactic acidosis/liver failure)
Perioperative fluid

Adverse Effects:

Contains potassium (risk in severe renal failure)
Contains lactate (caution in severe liver dysfunction—impaired metabolism to bicarbonate)
Can cause metabolic alkalosis if used in excess (conversion of lactate to bicarbonate)

Other Key Features:

Isotonic (273 mOsm/L), pH ~6.5
Contains sodium, potassium, calcium, chloride, and lactate (buffer)
No glucose

0.45% Sodium Chloride (Half-Normal Saline, 0.45 NS)

Indications:

Hyperosmolar states (e.g., hypernatremia, hyperosmolar hyperglycemic state)
Maintenance fluid (when ongoing fluid loss is hypotonic)

Adverse Effects:

Risk of hyponatremia (if used in excess or with high ADH)
May worsen cerebral edema
Not appropriate for resuscitation

Other Key Features:

Hypotonic (154 mOsm/L)
No calories

D5NS (5% Dextrose in Normal Saline)

Indications:

Maintenance fluid in NPO patients
Hypoglycemia prevention in patients requiring isotonic sodium
Hypernatremia (when sodium and free water replacement is needed)

Adverse Effects:

Hyperglycemia (especially in diabetics)
Hypernatremia or volume overload (with prolonged use)
Risk of phlebitis

Other Key Features:

Hypertonic (560 mOsm/L)
Provides 170 kcal/L
Not for resuscitation

D5 0.45 NS (5% Dextrose in Half-Normal Saline)

Indications:

Common maintenance fluid (post-op, pediatrics)
Hypoglycemia prevention in maintenance fluids

Adverse Effects:

Same as D5NS—hyperglycemia risk
Hyponatremia if free water excess is not balanced

Other Key Features:

Slightly hypertonic (406 mOsm/L)
Provides 170 kcal/L
Not suitable for resuscitation

D5W (5% Dextrose in Water)

Indications:

Correction of hypernatremia (provides free water)
Vehicle for medication administration
Dehydration with hypertonic states

Adverse Effects:

Rapid infusion can cause hyponatremia, water intoxication, cerebral edema
Hyperglycemia (especially in diabetics)
No electrolytes—can dilute serum sodium/potassium

Other Key Features:

Isotonic in bag (253 mOsm/L) but acts hypotonic after dextrose is metabolized
Provides 170 kcal/L
Not used for resuscitation

Albumin (5% or 25%)

Indications:

Hypovolemia (esp. with hypoalbuminemia, burns, liver disease, nephrotic syndrome)
Plasma exchange procedures
Cirrhotic patients with large-volume paracentesis (typically 4L or more)

Adverse Effects:

Volume overload/pulmonary edema
Anaphylactic reactions (rare)
Cost (significantly more expensive than crystalloids)

Other Key Features:

Colloid; increases plasma oncotic pressure
No risk of electrolyte imbalances
No calories

LR/0.45NS (Lactated Ringer’s in Half-Normal Saline)

Note: Rarely used, not commercially available as a premixed bag; sometimes compounded for special scenarios (e.g., pediatric or post-op care)
Indications/Adverse Effects:

Would combine risks and indications of both LR and 0.45NS—potential for hyponatremia and metabolic alkalosis
No standard clinical scenario; consult pharmacy and protocols if needed

Summary Table: Comparison of Common IV Fluids

Fluid	Tonicity	Main Electrolytes	Calories (kcal/L)	Indications	Key Adverse Effects
NS	Isotonic	Na+, Cl-	0	Shock, hypovolemia, DKA, hyponatremia	Hyperchloremic acidosis, volume overload, hypernatremia
LR	Isotonic	Na+, K+, Ca2+, Cl-, lactate	0	Burns, trauma, surgery, mild acidosis	Hyperkalemia, alkalosis, not for liver failure
0.45 NS	Hypotonic	Na+, Cl-	0	Maintenance, hyperosmolar states	Hyponatremia, cerebral edema
D5NS	Hypertonic	Na+, Cl-, dextrose	170	Maintenance, hypernatremia	Hyperglycemia, volume overload
D5 0.45NS	Hypertonic	Na+, Cl-, dextrose	170	Maintenance, post-op, peds	Hyponatremia, hyperglycemia
D5W	Isotonic*	Dextrose (acts hypotonic)	170	Free water, hypernatremia	Water intoxication, hyponatremia
Albumin	Iso/Hyper*	Protein	0	Hypoalbuminemia, cirrhosis, burns	Volume overload, cost, anaphylaxis

*D5W is isotonic in the bag but acts hypotonic in the body. Albumin comes in isotonic (5%) and hyperoncotic (25%) forms.

Bulleted Quick Reference by Fluid

Normal Saline (NS)

Most common resuscitation fluid
Good for hypovolemia, shock, metabolic alkalosis
Risk: acidosis, hypernatremia, fluid overload

Lactated Ringer’s (LR)

Good for burns, trauma, perioperative states
Contains potassium and lactate
Not for severe liver failure or hyperkalemia

0.45% NS

Maintenance fluid, correction of hyperosmolar states
Not for acute resuscitation
Risk: hyponatremia, cerebral edema

D5NS / D5 0.45NS

Commonly used as maintenance in NPO patients
Provides calories (170 kcal/L)
Risk: hyperglycemia, hyponatremia (with 0.45NS)

D5W

Used for free water replacement (hypernatremia)
Provides calories but NO electrolytes
Not for volume resuscitation; can cause hyponatremia

Albumin

Colloid; expands plasma volume
Used in hypoalbuminemia, cirrhosis, burns
Expensive; risk of anaphylaxis and volume overload

LR/0.45NS

Rare; custom mix; used rarely for tailored maintenance
Combines features of LR and hypotonic saline

Key Points and Clinical Pearls

NS and LR are the two most common fluids for initial resuscitation; choose based on acid-base status and underlying conditions.
Maintenance fluids often require some dextrose and a hypotonic base (e.g., D5 0.45NS).
Albumin is reserved for specific indications due to cost and limited evidence of mortality benefit over crystalloids.
Monitor for electrolyte changes and volume status regularly during IV fluid therapy.

6. References

Myburgh, J.A., & Mythen, M.G. (2013). Resuscitation fluids. New England Journal of Medicine, 369(13), 1243–1251. DOI: 10.1056/NEJMra1208627
Raghunathan, K., et al. (2015). Choice of fluids in severe illness: a review. Current Opinion in Critical Care, 21(4), 309–315. PMID: 26125185
Hoorn, E.J., & Zietse, R. (2017). Disorders of plasma sodium — causes, consequences, and correction. New England Journal of Medicine, 375, 1951–1960. DOI: 10.1056/NEJMra1604489
Cecconi, M., et al. (2014). Fluid therapy in the perioperative setting. The Lancet, 384(9958), 170–179. DOI: 10.1016/S0140-6736(14)61405-2
Guyton & Hall. Textbook of Medical Physiology. 15th Edition.

Scenario-Based Clinical Recommendations Table

Clinical Scenario	First-Choice Fluid(s)	Rationale	Alternatives / Cautions
Hypovolemic shock (trauma, sepsis)	NS or LR	Rapid volume expansion; isotonic fluids do not cause major fluid shifts	NS: Risk of acidosis with large volumes; LR: Contains K+, not ideal in severe hyperkalemia or advanced liver failure
Burns	LR	Closest match to plasma, replaces lost electrolytes, buffer for acidosis	NS can be used but may lead to hyperchloremic acidosis with large volume
Perioperative fluid	LR or NS	Isotonic fluids, minimize risk of fluid/electrolyte shift	Monitor for hyperkalemia with LR; avoid hypotonic solutions perioperatively
Diabetic Ketoacidosis (DKA)	NS	Restores volume, no added glucose, safe sodium	LR can be used but may affect interpretation of serum lactate; switch to D5 0.45NS when glucose <200 mg/dL
Hypernatremia	D5W, 0.45NS, or D5 0.45NS	Free water lowers sodium gradually	Avoid rapid correction (risk of cerebral edema); NS only if concurrent volume depletion
Hyponatremia (euvolemic/hypovolemic)	NS	Replaces sodium and water	D5NS/D5 0.45NS if maintenance also needed; avoid hypotonic fluids unless hyperosmolar state
Hyperkalemia	NS	Avoids additional potassium	LR contains K+, generally avoided
Severe liver failure	NS	Avoids lactate, which can accumulate due to impaired metabolism	LR may worsen lactic acidosis
Cirrhosis/large-volume paracentesis	Albumin	Increases oncotic pressure, prevents post-paracentesis hypovolemia	NS or LR do not correct hypoalbuminemia; colloid preferred
Nephrotic syndrome	Albumin (plus diuretic)	Restores oncotic pressure, augments diuresis	Crystalloids often insufficient
Hypoglycemia risk/NPO maintenance	D5 0.45NS or D5NS	Provides glucose and maintenance fluids	D5W if only water and calories needed; monitor for hyperglycemia
Cerebral edema/increased ICP	NS	Isotonic, avoids free water shift into brain	Avoid hypotonic solutions (D5W, 0.45NS)
Heart failure/renal failure	NS (small boluses) or albumin	Careful titration to avoid overload	Avoid LR in advanced CKD (K+), D5W/0.45NS (risk of overload/hyponatremia)
Pediatrics – dehydration	NS (bolus), then D5 0.45NS	NS for initial resuscitation, then maintenance with dextrose	Avoid hypotonic boluses; tailor ongoing fluids based on age/weight and ongoing losses
Geriatrics – maintenance/illness	NS or D5 0.45NS (adjust rate)	Avoid overload, monitor renal/cardiac status	Use lower rates and close monitoring
Medication vehicle	D5W or NS	Used for dilution/administration	Ensure compatibility

Explanations by Special Population:

Pediatrics

Resuscitation:

First-line: NS (20 mL/kg bolus)

Rapid restoration of intravascular volume in shock/dehydration (Feld et al., 2020)
Repeat boluses as needed, assess clinical response

LR is an alternative but less often used due to concern about calcium compatibility with certain drugs and slightly higher potassium content.

Maintenance Fluids:

D5 0.45NS with KCl (if not oliguric)

Traditional “Holiday-Segar” calculation for maintenance (see Holliday & Segar, 1957)
Provides glucose, electrolytes, and some free water
Reference: Feld LG, Neuspiel DR, Foster BA, et al. Clinical Practice Guideline: Maintenance Intravenous Fluids in Children. Pediatrics. 2018;142(6):e20183083.

Geriatrics

Special considerations:

Reduced renal/cardiac reserve: higher risk of fluid overload and electrolyte disturbances
First-line: NS (for resuscitation), D5 0.45NS for maintenance (rate adjusted for age and comorbidities)
Avoid rapid infusion and high volumes
Monitor closely: daily weights, strict I/O, frequent labs

Clinical Pearls:

Increased sensitivity to hypotonic fluids (hyponatremia, mental status changes)
Fluid restriction may be needed in CHF, CKD, or SIADH
Assess for signs of overload (crackles, edema, rapid weight gain)

References:

Bunn F, Hooper L, et al. Oral and intravenous therapy for preventing and treating dehydration in older people. Cochrane Database Syst Rev. 2015;2015(8):CD009647.

Renal Failure

Acute or Chronic Kidney Disease:

First-line for volume resuscitation: NS (small boluses, slow titration)
Avoid fluids containing potassium (e.g., LR) in advanced renal dysfunction or hyperkalemia risk
Albumin may be indicated for volume expansion when colloid is needed, but benefit vs risk is debated
Avoid hypotonic fluids (risk of hyponatremia, worsened fluid overload)
Monitor electrolytes, fluid status closely
Adjust volume based on urine output, risk of overload

Key Pearls:

Volume overload can precipitate pulmonary edema quickly in ESRD
Potassium-containing fluids (LR) usually avoided
Daily weights and lung auscultation essential

References:

KDIGO Clinical Practice Guideline for Acute Kidney Injury. Kidney Int Suppl. 2012;2(1):1-138.
Woodrow G. Volume overload in patients with chronic kidney disease. Clin Med (Lond). 2020;20(4):384-388.

Other Special Considerations

Heart Failure

Use small boluses of NS or albumin (colloid not superior in outcomes, but sometimes used)
Strict monitoring of fluid balance, may require fluid restriction

Liver Failure/Cirrhosis

NS preferred to avoid lactate
Albumin after large-volume paracentesis (>5L removed)

Burns

LR is the gold standard (Parkland formula) due to closest match to plasma electrolytes

Diabetes

Avoid D5-containing fluids in acute management of hyperglycemia/diabetic ketoacidosis until glucose is <200 mg/dL

Clinical Pearls Summary

Initial volume resuscitation: Use isotonic fluids (NS, LR), not hypotonic or dextrose-containing fluids.
Maintenance fluids: Tailor to patient’s ongoing needs, comorbidities, and risk for electrolyte derangement.
Monitor labs and clinical response: Fluids should be titrated based on clinical endpoints, not just standard formulas.
Special populations (pediatrics, elderly, renal failure) require slower rates, careful monitoring, and avoidance of certain fluids.

References

Feld LG, Neuspiel DR, Foster BA, et al. Clinical Practice Guideline: Maintenance Intravenous Fluids in Children. Pediatrics. 2018;142(6):e20183083.
Bunn F, Hooper L, et al. Oral and intravenous therapy for preventing and treating dehydration in older people. Cochrane Database Syst Rev. 2015;2015(8):CD009647.
KDIGO Clinical Practice Guideline for Acute Kidney Injury. Kidney Int Suppl. 2012;2(1):1-138.
Woodrow G. Volume overload in patients with chronic kidney disease. Clin Med (Lond). 2020;20(4):384-388.
Myburgh, J.A., & Mythen, M.G. Resuscitation fluids. N Engl J Med. 2013;369(13):1243–1251.
Guyton & Hall. Textbook of Medical Physiology. 15th Ed.
Hoorn, E.J., & Zietse, R. Disorders of plasma sodium — causes, consequences, and correction. N Engl J Med. 375:1951–1960.