Calculating 23.5% Saline Infusion Rate for Sodium Delivery
To deliver 232 mEq/hour of sodium chloride using 23.5% saline, you need to infuse approximately 59 mL/hour.
Calculation Method
The calculation is straightforward using the concentration of 23.5% saline:
23.5% saline contains 4 mEq/mL of sodium (23.5 g NaCl per 100 mL = 235 g/L = 4,017 mEq/L ≈ 4 mEq/mL)
Required infusion rate = 232 mEq/hour ÷ 4 mEq/mL = 58 mL/hour
Practical rate: 58-60 mL/hour to account for rounding
Critical Safety Considerations for Hypertonic Saline
This is an extremely concentrated solution requiring specific safety protocols:
Central venous access is strongly preferred for hypertonic saline concentrations above 3%, though peripheral administration of 3% HTS at rates up to 999 mL/h has been shown safe in emergency settings 1
23.5% saline is a high-alert medication requiring special storage and distribution safeguards, with mean times from order to administration of approximately 43 minutes when proper verification processes are followed 2
Monitor for extravasation risk - while 3% HTS shows no extravasation at rapid peripheral rates 1, 23.5% saline is significantly more concentrated and poses greater tissue injury risk if infiltrated
Context for CRRT Patients
For your 80 kg patient on CRRT requiring sodium supplementation:
Standard CRRT effluent rates of 20-25 mL/kg/h (1,600-2,000 mL/h for 80 kg) can cause significant sodium losses if using low-sodium dialysate 3, 4
Low-sodium CRRT fluids (119-126 mEq/L) are used intentionally in severe hyponatremia to prevent overly rapid correction, with mean sodium increases of only 3 mEq/L at 24 hours 5
If your patient requires 232 mEq/hour sodium supplementation, this suggests either: (1) severe ongoing sodium losses exceeding CRRT replacement, or (2) treatment of profound hyponatremia requiring controlled rapid correction 6, 7
Monitoring Requirements
Verify serum sodium every 2-4 hours during hypertonic saline infusion to prevent overcorrection beyond 6-8 mEq/L per 24 hours in chronic hyponatremia 5
Calculate actual delivered sodium by accounting for all sources: CRRT replacement fluid sodium content, IV fluids, and hypertonic saline supplementation 7
Adjust CRRT prescription - the mixing paradigm allows calculation of blood flow rates and post-filter D5W infusion to fine-tune sodium correction rates 7