D5W (5% Dextrose in Water)
D5W
Hypotonic free-water solution with dextrose
5% dextrose (50 g/L) in water — when dextrose is metabolized, the remaining solution is free water. Effectively a free-water source distributed across total body water (28–42 L in adult).
Indications
- •Free-water replacement in hypernatremia (target rate to drop Na⁺ ≤10 mEq/L per 24 h)
- •Diluent for medication infusions (insulin, certain antibiotics)
- •Treatment of hyperkalemia (with insulin — D50 IV bolus or D10 infusion)
- •Management of hypoglycemia (D50 1 amp = 25 g)
- •Diabetes insipidus volume replacement (with vasopressin)
Dosing
| Context | Adult | Pediatric |
|---|---|---|
| Hypernatremia free-water deficit | Calculate deficit = TBW × ((current Na − goal Na) / goal Na); replace over 48–72 h | — |
| Hypoglycemia rescue | 1 amp D50 (25 g) IV push — raises BG by ~50 mg/dL transiently | — |
| Hyperkalemia (with insulin) | 1 amp D50 IV with 10 U regular insulin | — |
Pharmacokinetics
Dextrose metabolized within minutes (insulin-dependent). Free water distributes across total body water.
Hemodynamic effects
Minimal volume expansion (only ~10% intravascular at 1 h since it distributes throughout TBW).
Respiratory effects
Risk of pulmonary edema if used as resuscitation fluid (don't — it's not).
Side effects
- !Hyperglycemia
- !Hyponatremia if used as primary resuscitation fluid
- !Cerebral edema — D5W given as bolus to a hyponatremic patient can drop Na further and cause herniation
- !No volume expansion in hypovolemia — patient will continue to be hypovolemic
Contraindications
- ×Hypovolemic shock (use isotonic fluid)
- ×Hyperglycemia uncontrolled
- ×Acute neurosurgical patient with risk of cerebral edema (relative — depends on Na status)
Clinical pearls
- ★NEVER A RESUSCITATION FLUID: D5W has only ~10% intravascular retention. Hypotensive patient + D5W bolus = persistent hypotension. Use NS, LR, or Plasmalyte for volume.
- ★HYPERNATREMIA CORRECTION RATE: drop serum Na ≤10 mEq/L per 24 h; faster correction risks cerebral edema. Calculate TBW = 0.6 × kg (men), 0.5 × kg (women).
- ★DKA TRANSITION: when BG drops to ~250 mg/dL during DKA insulin infusion, switch from NS/0.45 NS to D5-half-normal-saline — keeps insulin running while avoiding hypoglycemia.
- ★MEDICATION DILUENT CHOICE: phenytoin precipitates in D5W (must be NS); insulin OK in either; amiodarone OK in either. Always check the product insert.
- ★HYPOGLYCEMIA: 1 amp D50 = 25 g — but only transient (2-min insulin response). Follow with continuous D10 infusion if patient remains NPO or has long-acting hypoglycemic on board.
Other drugs in Crystalloids
- Normal Saline (0.9% NaCl)
0.9% sodium chloride in water — Na⁺ 154 mEq/L, Cl⁻ 154 mEq/L, osmolality 308 mOsm/kg. Distributes throughout the extracellular space; ~25–30% of infused volume remains intravascular at 30–60 min.
- Lactated Ringer's (LR / Hartmann's solution)
Na⁺ 130, Cl⁻ 109, K⁺ 4, Ca²⁺ 3, lactate 28 mEq/L; osmolality 273 mOsm/kg (slightly hypotonic). Lactate metabolized by liver to bicarbonate, providing buffering. Closer to plasma electrolyte composition than saline.
- Plasma-Lyte 148 (and similar balanced solutions)
Na⁺ 140, Cl⁻ 98, K⁺ 5, Mg²⁺ 3, acetate 27, gluconate 23 mEq/L; osmolality 294 mOsm/kg. Acetate and gluconate metabolize independent of liver perfusion (unlike lactate), making it useful in liver failure / shock states. No calcium → fully compatible with blood products.
- Hypertonic Saline 3% (and 23.4%)
3% NaCl: Na⁺ 513 mEq/L, osmolality 1027 mOsm/kg. 23.4% NaCl: Na⁺ 4000 mEq/L. Pulls water from brain parenchyma across an intact blood-brain barrier into the intravascular space — reduces ICP and treats severe hyponatremia.
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Suggested reading
- •Miller's Anesthesia, 9e
- •Stoelting & Hines, Pharmacology & Physiology in Anesthetic Practice, 6e
