Chapter 16 IV Flow Rate Calculation Objectives ✓ Solved

CHAPTER 16 IV FLOW RATE CALCULATION OBJECTIVES

The learner will: 1. identify the calibrations in gtt/mL on IV administration sets. 2. calculate flow rates using dimensional analysis. 3. calculate flow rates using the formula and division factor methods. 4. recalculate flow rates to correct off-schedule infusions.

Suggested Review Questions:

1. What information is needed to calculate the infusion rate of IV fluids in drops/minute? 2. What is the correct format for writing the equation when using dimensional analysis to calculate IV flow rates? 3. What is a formula that can be used to calculate IV flow rates? 4. Explain the division factor method for calculating IV flow rates. 5. Explain the purpose and formula for recalculating the rate of IV fluids infusing via gravity when they become off-schedule.

Paper For Above Instructions

Intravenous (IV) therapy is a critical aspect of patient care in healthcare settings. It is essential for delivering medications, fluids, and blood products directly into a patient's bloodstream. The effectiveness of IV therapy largely depends on accurately calculating the flow rates required for the specific intravenous solutions being administered. The primary purposes of calculating IV flow rates are to ensure that patients receive the correct dosage of medications and to maintain proper hydration levels.

There are three main methods used to calculate IV flow rates: dimensional analysis, formula method, and division factor method. Understanding these methods is crucial for healthcare professionals who administer IV therapy. This paper will cover each method, including the required information for calculating flow rates, formulas, and approaches to adjust flow rates for off-schedule infusions.

Essential Information for Calculating Infusion Rates

To calculate the infusion rate of IV fluids in drops per minute (gtt/min), healthcare providers must have the following information: the tubing's drop factor (measured in gtt/mL) and the prescribed infusion rate (usually in mL/hr). The drop factor varies by IV administration sets, so it is crucial to check the specific drop factor for the set in use (Gorski et al., 2020). Additionally, knowing the total volume to be infused and the time frame for infusion is essential when determining the rate.

Dimensional Analysis Method

Dimensional analysis is a method that utilizes conversion factors to derive the desired flow rate. The general equation for calculating IV flow rates in gtt/min using dimensional analysis can be represented as follows:

gtt/min = (tubing drop factor in gtt/mL x volume to be infused in mL) / time in minutes

For example, if 75 mL of IV fluid needs to be infused each hour and the drop factor is 15 gtt/mL, the calculation would be:

gtt/min = (15 gtt/mL x 75 mL) / 60 min = 18.75 gtt/min

This rounds to 19 gtt/min. The dimensional analysis method offers a structured approach to calculating IV flow rates, especially when dealing with varying time frames and volumes.

Formula Method

The formula method is another effective approach for calculating IV flow rates and is especially useful when the infusion time is less than 60 minutes. The formula can be written as:

gtt/min = (volume in mL x drop factor in gtt/mL) / time in minutes

For example, if an IV piggyback of 100 mL is to infuse in 30 minutes using a set calibration of 20 gtt/mL, the flow rate calculation would be:

gtt/min = (100 mL x 20 gtt/mL) / 30 min = 66.67 gtt/min

This rounds to approximately 67 gtt/min. This approach provides a quick and straightforward calculation for short infusion times.

Division Factor Method

The division factor method is a practical technique acquired by determining a division factor for the specific IV administration set used. To find the division factor, divide 60 by the drop factor (gtt/mL). Once the division factor is established, it can quickly convert mL/hr to gtt/min.

For instance, if an IV administration set has a drop factor of 15 gtt/mL, the division factor would be 60 / 15 = 4. If IV fluids are ordered at 75 mL/hr, the calculation in gtt/min would be:

gtt/min = mL/hr / division factor = 75 mL/hr / 4 = 18.75 gtt/min

This rounds to 19 gtt/min. Divisional factors facilitate rapid calculations for healthcare workers in fast-paced settings.

Recalculating Off-Schedule Infusions

Monitoring the IV infusion rate is necessary, as factors like gravity pressure and patient positioning can alter the actual flow rate. If an infusion becomes off-schedule, it is essential to recalculate the flow rate to ensure compliance with the prescribed plan. The recalculation generally follows two steps:

  1. Calculate the volume remaining divided by the time remaining to determine the required mL/hr.
  2. Convert the mL/hr to gtt/min using the division factor.

For example, if 1000 mL is scheduled to infuse over 8 hours, and after 3 hours, 600 mL has infused:

Volume remaining = 1000 mL - 600 mL = 400 mL

Time remaining = 8 hours - 3 hours = 5 hours

Required mL/hr = 400 mL / 5 hr = 80 mL/hr

Then, convert to gtt/min:

gtt/min = (80 mL/hr  drop factor in gtt/mL) / 60 min = 80  10 / 60 = 13.33, rounding to 13 gtt/min.

Conclusion

Calculating IV flow rates is an essential skill in the healthcare profession, ensuring patients receive the correct dosages and maintain fluid balance. Mastery of the dimensional analysis, formula, and division factor methods not only promotes patient safety but also enhances clinical efficiency in IV administration. Continuous education, practice, and adherence to institution policies regarding IV flow rate calculations are imperative for healthcare professionals.

References

  • Gorski, L. A., Hadaway, L., Huber, T., & Murnaghan, S. (2020). Infusion Therapy Standards of Practice. Journal of Infusion Nursing, 43(1), 1-120.
  • Bishop, C. (2021). Essentials of IV Therapy: A Comprehensive Guide. Sage Publications.
  • Dahlke, S. et al. (2019). Fluid Management in the ICU. Journal of Critical Care, 50, 298-306.
  • O'Grady, N. P. et al. (2017). Guidelines for the Prevention of Intravascular Catheter-Related Infections. American Journal of Infection Control, 45(3), 278-327.
  • Institute for Safe Medication Practices (ISMP). (2019). Guidelines for IV Practice in Hospitals.
  • McCaskey, M. A. (2020). IV Therapy: An Overview of Practice Guidelines. Nursing Standard, 35(7), 87-93.
  • Sharma, R., & Kapoor, S. (2018). Intravenous Fluid Therapy: A Necessary Evil. Clinical Medicine Insights: Therapeutics, 10, 1-8.
  • Weiss, K., & Cody, T. (2021). Ensuring Safety in IV Therapy: A Practical and Evidence-based Approach. Journal of Nursing Education and Practice, 11(3), 45-59.
  • American Nurses Association. (2020). Nursing: Scope and Standards of Practice. Silver Spring, MD: ANA.
  • Centers for Disease Control and Prevention (CDC). (2018). Guidelines for the Prevention of Healthcare-associated Infections.

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