From the Guidelines
The best maintainable fluid for most applications is an isotonic solution, such as 0.9% sodium chloride (normal saline) or Plasma-Lyte, as it closely matches the body's electrolyte composition and helps maintain intravascular volume effectively. According to the clinical practice guideline on maintenance intravenous fluids in children 1, isotonic fluids have a sodium concentration similar to plasma (135–144 mEq/L) and are superior to hypotonic fluids in preventing hyponatremia. The study found that the number needed to treat with isotonic fluids to prevent hyponatremia was 7.5 across all included studies.
When considering the choice of maintainable fluid, it's essential to take into account the patient's underlying condition, electrolyte status, and acid-base balance. For example, in cases of significant blood loss, blood products would be more appropriate than crystalloids for maintaining oxygen-carrying capacity. Additionally, the use of balanced crystalloid solutions like Plasma-Lyte may be preferred for long-term maintenance as they have electrolyte concentrations that better match physiological levels and help avoid hyperchloremic metabolic acidosis that can occur with prolonged normal saline use 1.
Key considerations for fluid management include:
- Using isotonic solutions to prevent hyponatremia
- Avoiding hypotonic fluids, which can lead to hyponatremia
- Considering the use of balanced crystalloid solutions for long-term maintenance
- Taking into account the patient's underlying condition, electrolyte status, and acid-base balance when selecting a maintainable fluid
- Avoiding fluid overload, which can cause hyperosmolar states, hyperchloremic acidosis, and decreased renal blood flow and glomerular filtration rate 1.
Overall, the choice of maintainable fluid should be based on the individual patient's needs and clinical situation, with a focus on preventing complications and promoting optimal outcomes.
From the Research
Best Maintainable Fluid
The best maintainable fluid is a topic of ongoing research and debate. Several studies have compared the effects of different fluids on patient outcomes.
- Normal saline solution and lactated Ringer's solution have been shown to have similar effects on quality of recovery in stable emergency department patients 2.
- Intraoperative use of normal saline or lactated Ringer's solution has been found to have similar risks of acute kidney injury, with no significant difference in AKI risk between the two fluids 3.
- Hypertonic saline-dextran solution has been shown to be effective for resuscitating severely dehydrated calves with diarrhea, with a more rapid and sustained response compared to lactated Ringer's solution 4.
- A novel balanced isotonic sodium solution has been found to be safer than normal saline in protecting young children undergoing major surgery against the risk of increasing plasma chlorides and subsequent metabolic acidosis 5.
- Isotonic solutions have been shown to reduce the risk of hyponatraemia compared to hypotonic solutions for maintenance intravenous fluid administration in children 6.
Key Findings
- Normal saline and lactated Ringer's solution have similar effects on patient outcomes in certain contexts.
- The choice of fluid may depend on the specific patient population and clinical context.
- Isotonic solutions may be preferred over hypotonic solutions for maintenance intravenous fluid administration in children to reduce the risk of hyponatraemia.
- Hypertonic saline-dextran solution may be effective for resuscitating severely dehydrated patients.
Fluid Comparison
- Normal saline: commonly used, but may cause hyperchloremic acidosis 3.
- Lactated Ringer's solution: similar effects to normal saline in some contexts, but may be associated with a lower risk of hyperchloremic acidosis 2, 3.
- Hypertonic saline-dextran solution: effective for resuscitating severely dehydrated patients, but may not be suitable for all patient populations 4.
- Isotonic solutions: reduce the risk of hyponatraemia compared to hypotonic solutions for maintenance intravenous fluid administration in children 6.