From the Guidelines
Normal saline (0.9% NaCl) is the preferred choice for maintenance IV fluids in patients with acute ischemic stroke, as it provides adequate hydration without exacerbating ischemic brain edema, according to the guidelines from the American Heart Association/American Stroke Association 1. When considering maintenance IV fluid rationales, it is essential to prioritize euvolemia, as both hypovolemia and hypervolemia can have adverse effects on patients with acute ischemic stroke.
- Hypovolemia may predispose to hypoperfusion and exacerbate the ischemic brain injury, cause renal impairment, and potentiate thrombosis.
- Hypervolemia may exacerbate ischemic brain edema and increase stress on the myocardium. The use of isotonic solutions like 0.9% saline is recommended, as they are more evenly distributed into the extracellular spaces (interstitial and intravascular) and may be better for patients with acute ischemic stroke 1. In contrast, hypotonic solutions such as 0.45% saline may exacerbate ischemic brain edema, as a substantial proportion of these solutions is distributed into the intracellular spaces.
- Daily fluid maintenance for adults can be estimated as 30 mL per kilogram of body weight, and rapid replacement of the depleted intravascular volume followed by maintenance intravenous fluids is reasonable for patients who are hypovolemic at presentation.
- Extra precaution is needed in patients who are especially vulnerable to intravascular volume overload, such as those with renal or heart failure, and treatment of patients with specific conditions, such as syndrome of inappropriate antidiuretic hormone secretion or fever, requires modifications to standard hydration protocols 1.
From the Research
Maintenance IV Fluid Rationale
- The choice between normal saline and 1/2 normal saline for maintenance IV fluid depends on the patient's underlying condition and fluid status.
- In patients with heart failure, fluid management is crucial to prevent overhydration and dehydration, as both can lead to adverse outcomes 2.
- The "5B" approach, which considers balance of fluids, blood pressure, biomarkers, bioimpedance vector analysis, and blood volume, can help guide fluid management in these patients 2.
- In patients with renal failure, normal saline may be a better choice for irrigation fluid during procedures like percutaneous nephrolithotomy (PCNL) to avoid electrolyte disturbances and fluid overload 3.
- The use of distilled water for irrigation in renal failure patients can lead to hyponatremia, drops in hematocrit level, and alterations in serum potassium level, making normal saline a safer choice 3.
Considerations for Normal Saline vs 1/2 Normal Saline
- Normal saline is isotonic and can help maintain fluid balance without causing significant shifts in electrolyte levels.
- 1/2 normal saline, on the other hand, is hypotonic and may be used in patients who require free water replacement, but its use should be cautious in patients with renal failure or heart failure to avoid fluid overload.
- The decision to use normal saline or 1/2 normal saline should be based on the individual patient's needs and underlying condition, taking into account factors such as fluid status, electrolyte levels, and renal function 2, 3.