IV Flow Rates and Administration

Introduction to IV Flow Rates

• IV flow rates are the volume of medication delivered per unit of time via intravenous (IV) route.
• Also known as drip rates or infusion rates.
• Common flow rate units: milliliters per hour (mL/hr) or drops per minute (gtts/min).

IV Administration Sets

• IV sets deliver IV solutions to patients.
• Types:
  • Gravitational drip chamber: Uses gravity to control the flow rate.
  • Electronic infusion pumps: Precisely regulate the flow rate.
• Drop factor: The number of drops needed to equal one milliliter (gtts/mL).
  • Macro sets: Have larger drops (e.g., 10 gtts/mL).
  • Micro sets: Have smaller drops (e.g., 60 gtts/mL).

Common Conversions

• Conversions are critical for IV flow rate calculations.
• Key conversions:
  • 1 liter (L) = 1000 milliliters (mL)
  • 1 hour (hr) = 60 minutes (min)
  • 1 gram (g) = 1000 milligrams (mg)
  • 1 milligram (mg) = 1000 micrograms (µg)

Solving Flow Rate Calculations

• Two methods:
  • Method 1: Fraction Cancellation: Set up fractions that cancel like units. Multiply the fractions to find the desired unit.
  • Method 2: Equivalent Fractions: Set up equivalent fractions with matching units in the numerators and denominators. Cross-multiply and then divide to solve for the unknown variable (x).

Example Calculations

• Example 1: 1200 mL of normal saline (0.9% sodium chloride) infused over 8 hours. Find the mL/hr.
  • Method 1: (1200 mL/8 hr) x (1 hr/1) = 150 mL/hr
  • Method 2: (1200 mL/8 hr) = (x mL/1 hr) --> x = 150 mL/hr
• Example 2: 1200 mL of normal saline infused over 8 hours. Find the mL every 10 minutes.
  • Method 1: (1200 mL/480 min) x (10 min/1) = 25 mL/10 min
  • Method 2: (1200 mL/480 min) = (x mL/10 min) --> x = 25 mL/10 min
• Example 3: 500 mL of D5W (dextrose 5% in water) infused over 6 hours. Find the flow rate in gtts/min using a drip rate of 60 gtts/mL.
  • Method 1: (60 gtts/mL) x (500 mL/6 hr) x (1 hr/60 min) = 83 gtts/min
  • Method 2: (60 gtts/1 mL) = (x gtts/500 mL) --> x = 30,000 gtts; (30,000 gtts/360 min) = 83 gtts/min
• Example 4: 1 L of D5W infused over 6 hours using a 10 gtts/mL IV set. Find the flow rate in gtts/min.
  • Method 1: (1000 mL/1) x (10 gtts/1 mL) x (1 hr/60 min) x (1/6 hr) = 28 gtts/min
  • Method 2: (10 gtts/1 mL) = (x gtts/1000 mL) --> x = 10,000 gtts; (10,000 gtts/360 min) = 28 gtts/min
• Example 5: Vancomycin 1.5 g in 500 mL at a rate of 10 mg/min. Find the time to deliver the medication.
  • Method 1: (1 min/10 mg) x (1000 mg/1 g) x (1.5 g/1) = 150 min (2.5 hr)
  • Method 2: (1000 mg/1 g) = (x mg/1.5 g) --> x = 1500 mg; (1500 mg/10 mg/min) = 150 min (2.5 hr)

Key Points

• IV flow rates are crucial for patient safety.
• Conversions and calculations are essential for accurate flow rate determination.
• Drip factor is essential in IV flow rate calculations.
• Always double-check calculations and units for accuracy.

Vancomycin Administration

• Administer IV vancomycin slowly (no faster than 1 g/hr or 10 mg/min) to prevent vancomycin flushing syndrome (VFS).

Additional Notes

• Some calculations may provide extraneous information.
• Carefully read the problem to identify the desired unit and relevant information.
• Method 1 involves canceling units through multiplication of fractions.
• Method 2 uses equivalent fractions and cross-multiplication to solve for the unknown variable.
• Always round to the nearest whole number when dealing with drops per minute.