How to prepare 0.18% sodium chloride with bicarbonate (bicarb) IV fluid?

Preparation of 0.18% Sodium Chloride with Bicarbonate IV Fluid

To prepare 0.18% sodium chloride with bicarbonate IV fluid, dilute sodium bicarbonate 8.4% solution 1:1 with sterile water or normal saline to achieve 4.2% concentration, then add this to 0.18% sodium chloride solution according to the specific clinical indication and target bicarbonate concentration needed.

Understanding the Components

The question asks about preparing a hypotonic saline solution (0.18% NaCl) combined with bicarbonate, which is not a standard commercially available preparation. This requires understanding both components:

• Sodium bicarbonate 8.4% is the standard hypertonic stock solution available, containing 1 mEq/mL of both Na+ and HCO3- 1
• 0.18% sodium chloride is a hypotonic solution (approximately 31 mEq/L sodium) that must be prepared by dilution 2

Preparation Method Using Dilution Principles

Step 1: Prepare the Bicarbonate Component

• For pediatric patients under 2 years: Dilute sodium bicarbonate 8.4% solution 1:1 with normal saline or sterile water to achieve 4.2% concentration (0.5 mEq/mL) 3
• For children ≥2 years and adults: The 8.4% solution may be used without dilution, though dilution is often performed for safety 3

Step 2: Calculate Required Volumes

Using the formula C₁V₁ = C₂V₂ (where C₁ is initial concentration, V₁ is initial volume, C₂ is target concentration, and V₂ is final volume):

• Determine the final volume needed for your clinical application 4
• Calculate the volume of each component (0.18% NaCl and diluted bicarbonate) required to achieve your target concentrations 4

Step 3: Mixing Protocol

• Withdraw the calculated volume of diluted bicarbonate solution aseptically 2
• Transfer into the 0.18% sodium chloride solution using sterile technique 4
• Mix thoroughly by gentle inversion to ensure homogeneous distribution 4

Critical Safety Considerations

Compatibility Issues

• Never mix sodium bicarbonate with calcium-containing solutions in the same IV line without adequate barrier fluid separation, as this causes calcium carbonate precipitation 5, 3
• Do not mix with vasoactive amines (norepinephrine, dobutamine) as bicarbonate will inactivate catecholamines 3
• Flush IV lines with normal saline before and after bicarbonate administration if other medications are being given 3

Concentration-Specific Warnings

• Hypertonic bicarbonate (8.4%) has osmolality of 2 mOsmol/mL, making it extremely hypertonic and requiring dilution for safety 3
• The 4.2% concentration reduces risk of hyperosmolar complications that can compromise cerebral perfusion 3

Storage and Labeling

• Label clearly with medication name, concentration, date/time of preparation, and expiration time 4
• Prepare immediately before use for optimal efficacy 4
• Discard after 24 hours if not used immediately 4
• Protect from light during storage by covering with amber occlusive material 6

Clinical Context: When This Preparation Is Used

This combination is not a standard preparation in most clinical guidelines. The evidence strongly supports:

• Isotonic bicarbonate solutions (150 mEq/L) are preferred for continuous infusion in metabolic acidosis or sodium channel blocker toxicity 3
• Standard 0.9% sodium chloride is equivalent or superior to bicarbonate for most indications, including contrast nephropathy prevention 7, 8, 9

If Preparing for Specific Indications

• For severe metabolic acidosis (pH <7.1): Use standard 4.2% or 8.4% bicarbonate with appropriate dosing (1-2 mEq/kg), not hypotonic preparations 3
• For continuous infusion: Prepare 150 mEq/L solution by diluting bicarbonate appropriately, infused at 1-3 mL/kg/hour 3
• For pediatric maintenance fluids: If combining hypotonic saline with bicarbonate for a specific metabolic indication, ensure adequate ventilation is established first 3

Common Pitfalls to Avoid

• Do not use this preparation for routine hydration - isotonic solutions are preferred 7, 8, 9
• Ensure adequate ventilation before administration - bicarbonate produces CO2 that must be eliminated to prevent paradoxical intracellular acidosis 3
• Avoid in hypoperfusion-induced lactic acidemia with pH ≥7.15 - no benefit demonstrated and potential harm 3
• Monitor serum sodium closely - target <150-155 mEq/L to avoid hypernatremia 3
• Check arterial blood gases every 2-4 hours during active therapy to guide dosing 3