IV SOLUTIONS - MARCH 11

Follow-Up Process and Exam Reflection

• Overview: A follow-up process is emphasized to aid students in identifying struggles from the previous exam and improving in future assessments.
  • Exam review opportunities are scheduled for the following Tuesday to assess areas of difficulty.
  • Clarification: This session is not intended for simply regaining lost points.

Importance of Class Attendance

• Attendance Concerns: Many students were unable to attend the last class due to an exam for drug action on the same day.
  • Students who missed the class are encouraged to watch the recording and address any questions to Dr. Paul.
  • The upcoming second exam covers a limited number of topics, making thorough preparation essential.

Today's Focus: Intravenous (IV) Infusions and Parenteral Admixtures

• Topics Covered:
  • Importance of understanding various calculations involved in preparing infusions and admixtures.
• Key Calculations: Different methods will be introduced based on patient conditions, weight, and disease states.

Types of Parenteral Routes

• Parenteral administration delivers medications outside of the gastrointestinal tract, directly affecting the bloodstream, which requires strict sterility due to the risk of pathogens.
• Types of Parenteral Routes:
  • IV (Intravenous): Fastest method of drug delivery into the circulation.
  • IM (Intramuscular): Limited volume injected into the muscular space.
  • SC (Subcutaneous): Volume administered is less than 2 mL beneath the skin.
  • ID (Intradermal): Very small volumes (0.05 to 0.1 mL) administered in the dermis.
  • Intrathecal: Drug delivery into the spinal canal.
  • Intra-arterial: Direct injection into an artery.
  • Intracardiac: Direct delivery into the heart.
  • Intraperitoneal: Delivery into the peritoneal cavity surrounding organs.

Administration Techniques for IV Drugs

Types

• Bolus: Immediate delivery in a rapid injection using a syringe, designed for instant effects (e.g., adenosine, morphine).
• Push: Similar to bolus with rapid injection, typically for quick symptom relief.
• Infusion: Slow and continuous administration over time, can last from minutes to hours using an IV bag (e.g., vancomycin).

IV Infusion Solutions

• Common Solutions: Normal saline, different concentrations of sodium chloride and dextrose; isotonic solutions are vital for certain infusions but not always necessary.

Rate of Flow Calculations

Concept

• Calculating the rate of flow is essential for safe and effective drug administration.
• Rate of flow is measured in drops per minute and is determined by an equation.
• Equation:$r = \frac{V \times D}{T}$
  • Where:
  • r = rate of flow (drops/minute)
  • V = volume (mL)
  • D = drop factor (drop/mL from device)
  • T = time (min)
• Always ensure that the volume is converted to mL when calculating drop rates.

Drop Factors

• Macro drip: 10, 15, or 20 drops/mL (standard drop factors for larger volume solutions).
• Micro drip: 60 micro drops/mL (smaller volume solutions requiring precise measurement).

Example Calculation

• Question: 1500 mL saline is ordered over 12 hours, drop factor is 15 GTT/mL. Calculate drops/minute.
  • Calculate the total time in minutes:
  • 12 hours = 720 minutes
  • Plug values into the equation:
    $r = \frac{1500 \times 15}{720} = 31.25$
  • Round to a whole number: 31 drops/minute.

IV Admixtures

Concept

• Admixtures involve combining additional drug solutions with a primary IV solution, necessitating careful volume and concentration calculations to ensure safe and effective dosing.
• Example Calculation: Patient weight, target dosage per kg, volume determination, and total drug volume in solution.

Example Problem

• Medication Order: 0.25 mg/kg amphotericin B for a 154 lb patient, added to 500 mL D5W.
• Conversions and Calculations:
  1. Convert the weight to kg: $154~\text{lb} = \frac{154}{2.2} \approx 70~\text{kg}$
  2. Calculate required amphotericin: 70 kg * 0.25 mg/kg = 17.5 mg
  3. Withdraw volume from the vial providing measured dosage.

Concentration and Delivery Rates

• Concentration Calculations: Based on the total drug volume in the IV bag after admixture.
• Clarification of Rates: Understanding delivery rates in mg/minute or specific flow rates important for patient safety and treatment efficacy.

Pediatric Dosing

• Pediatric dosing is weight-based and requires concentration calculations like those used for adults but must consider smaller volumes and dosing accuracy due to smaller patient sizes.

Final Questions and Summary

• Completing practice problems and asking clarification questions is vital before moving onto practical scenarios involving real patients.