Side Effects of Bolus Dextrose-Normal Saline (DNS)
Bolus administration of DNS can cause significant hyperglycemia, electrolyte imbalances (particularly hypernatremia and hypokalemia), fluid overload complications, and in specific populations, serious adverse events including neonatal hypoglycemia and acute hypotension.
Primary Metabolic and Electrolyte Complications
Hyperglycemia
The most common and clinically significant side effect is hyperglycemia, particularly when dextrose-containing solutions are given as boluses. Even a relatively small volume of 500 mL of 5% dextrose in normal saline causes plasma glucose to exceed 10 mmol/L in 72% of non-diabetic patients, with mean levels reaching 11.1 mmol/L within 15 minutes of completion 1. This effect is transient but clinically significant.
In diabetic or glucose-intolerant patients, dextrose solutions require particular caution 2. The FDA label explicitly warns that solutions containing dextrose should be used with caution in patients with overt or subclinical diabetes mellitus, or carbohydrate intolerance for any reason 2.
Electrolyte Disturbances
Hypernatremia and metabolic acidosis are significant risks, particularly with larger volumes. Infusion of more than one liter of isotonic (0.9%) sodium chloride per day can supply more sodium and chloride than normally found in serum, exceeding normal tolerance and resulting in hypernatremia 2. This may also cause a loss of bicarbonate ions, resulting in an acidifying effect 2.
Hypokalemia may develop during parenteral administration of hypertonic dextrose solutions 2. Sufficient amounts of potassium should be added to dextrose solutions administered to fasting patients with good renal function, especially those on digitalis therapy 2.
Studies comparing DNS to Ringer's lactate show statistically significant differences in serum chloride levels, with DNS associated with higher rates of hyperchloremic metabolic acidosis (14% at 24 hours versus 2.8% with Ringer's lactate) 3.
Cardiovascular Complications
Acute Hypotension
Rapid bolus administration of hyperosmotic dextrose solutions can cause acute, severe hypotension. A case report documents a 60-year-old intubated patient who developed acute decreases in systemic arterial blood pressure with administration of ≤50 mL of 50% dextrose 4. Animal studies suggest this hyperosmolar-induced hypotension results from a neural reflex triggered by osmoreceptors and may be avoided by administering the hyperosmotic solution slowly to allow for admixture and decreased osmotic load 4.
Fluid Overload
Fluid overload can precipitate pulmonary edema or adult respiratory distress syndrome (ARDS), which can worsen cerebral edema 5. These solutions should be used with care in patients with hypervolemia, renal insufficiency, urinary tract obstruction, or impending or frank cardiac decompensation 2.
Sodium-containing solutions should be administered with caution to patients receiving corticosteroids or corticotropin, or to other salt-retaining patients 2. Care should be exercised in administering solutions containing sodium to patients with renal or cardiovascular insufficiency, with or without congestive heart failure, particularly if they are postoperative or elderly 2.
Special Population Risks
Obstetric and Neonatal Complications
In pregnant women undergoing cesarean section, large amounts of dextrose (57.5g) cause significant fetal and neonatal harm 6. This includes:
- Elevated umbilical cord venous glucose (11.7 mmol/L)
- Elevated fetal insulin levels (70 ± 7 microU/ml)
- Decreased glucagon levels (24 ± 5.3 pg/ml)
- Arterial pH decrease to 7.19
- Neonatal hypoglycemia (1.8 ± 0.22 mmol/L) due to raised insulin levels
- Delayed release of glucagon at 2 hours of age
- Higher incidence of neonatal jaundice
The study recommends limiting dextrose infusions immediately before delivery to no more than 6 g/h 6. Caution should be exercised, and fluid balance, glucose and electrolyte concentrations, and acid-base balance of both mother and fetus should be evaluated periodically 2.
Pediatric Considerations
In children, DNS carries specific risks of hyponatremia and hyperglycemia. The dosage selection and constant infusion rate must be selected with caution in pediatric patients, particularly neonates and low birth weight infants, because of the increased risk of hyperglycemia/hypoglycemia 2. Frequent monitoring of serum glucose concentrations is required 2.
A study comparing 0.45% versus 0.9% saline in 5% dextrose found that hypotonic solutions (0.45%) caused significant falls in serum sodium and increased risk of hyponatremia at 12 and 24 hours 7. In neonates or very small infants, even small volumes of fluid may affect fluid and electrolyte balance 2.
Renal Complications
Acute kidney injury (AKI) can occur, though incidence is relatively low. In one study, AKI occurred in 1.4% at 24 hours and 2.8% at 48 hours with Ringer's lactate dextrose, and 0% at 24 hours and 1.4% at 48 hours with DNS 3.
Critical Monitoring Requirements
The FDA label mandates that clinical evaluation and periodic laboratory determinations are necessary to monitor changes in fluid balance, electrolyte concentrations, and acid-base balance during prolonged parenteral therapy or whenever the condition of the patient warrants such evaluation 2. Significant deviations from normal concentrations may require tailoring of the electrolyte pattern.
Common Pitfalls to Avoid
- Do not use excessive volumes or rapid boluses in patients with cardiac or renal insufficiency
- Avoid hyperosmotic dextrose boluses without slow administration to prevent acute hypotension 4
- Do not administer large dextrose loads (>6g/h) to pregnant women near delivery 6
- Monitor glucose closely in diabetic patients, children, and neonates 2
- Limit isotonic saline to <1 liter/day when possible to avoid hypernatremia and acidosis 2
- Add potassium supplementation to dextrose solutions in fasting patients with good renal function 2