IV Fluid Rate Maintenance for a Dental Sedation Case

When administering IV fluids for a dental sedation case, it is important to account for baseline maintenance needs, preoperative fluid deficits (due to NPO status), and ongoing losses.

1. Maintenance IV Fluid Rate Calculation

A commonly used formula for calculating maintenance IV fluid rates in adults is based on the 4-2-1 rule:

• 4 mL/kg/hr for the first 10 kg
• 2 mL/kg/hr for the next 10 kg
• 1 mL/kg/hr for each additional kg over 20 kg

Example Calculation for a 70 kg Patient

• First 10 kg → 4 × 10 = 40 mL/hr
• Next 10 kg → 2 × 10 = 20 mL/hr
• Remaining 50 kg → 1 × 50 = 50 mL/hr
  Total maintenance fluid rate = 110 mL/hr

2. Fluid Deficit Due to NPO for 8 Hours

To estimate the fluid deficit, multiply the hourly maintenance rate by the duration of NPO:

• Deficit = Maintenance Rate × NPO Hours
• Example for a 70 kg patient:
  • 110 mL/hr × 8 hrs = 880 mL fluid deficit

This deficit should be replaced over the first few hours of the procedure:

• 50% in the first hour
• 25% in the second hour
• 25% in the third hour

3. Total IV Fluid Rate During the Procedure

The total fluid rate should combine maintenance fluids + NPO replacement as follows:

• First Hour: (110 mL/hr maintenance) + (440 mL deficit replacement) = 550 mL/hr
• Second Hour: (110 mL/hr maintenance) + (220 mL deficit replacement) = 330 mL/hr
• Third Hour: (110 mL/hr maintenance) + (220 mL deficit replacement) = 220 mL/hr
• Beyond 3rd Hour: Maintain 110 mL/hr if no additional fluid loss occurs

4. Fluid Choice

• Balanced crystalloids (e.g., Lactated Ringer’s (LR) or Plasma-Lyte) are preferred over 0.9% Normal Saline (NS) to reduce the risk of metabolic acidosis.
• Dextrose-containing fluids (e.g., D5LR or D5NS) may be considered in pediatric cases to prevent hypoglycemia.

5. Adjustments Based on Patient Needs

• Hypovolemia or Hypotension: Increase fluid rate or give boluses of 250-500 mL LR or NS as needed.
• Cardiac or Renal Disease: Avoid fluid overload—consider reduced rates and titrate carefully.

CLINICAL PEARL:

Know how to run your fluids and why. Keeping a patient properly hydrated will avoid cardiovascular problems and diminish post sedation nausea and vomiting!