Welcome to your free NCLEX reviewer and practice questions quiz for IV flow rate calculations and formulas. This quiz aims to help student nurses review and test their competence in the intravenous flow rate calculation.
IV Flow Rate Calculation Nursing Test Bank
The nursing test bank for IV flow rate calculations below is separated into two sets of quizzes. Included topics are IV flow rate calculation, calculating for drops per minute, calculating for milliliters per hour, and total infusion time. If you need a quick review, please read the IV flow rate reviewer below.
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Quizzes included in this guide are:
IV Flow Rate Calculations Reviewer & Formulas
The IV flow rate study guide below will help refresh your memory on calculating IV flow rates, including a refresher on the formulas and nursing considerations when maintaining IV therapy.
For more information about IV fluids, visit our IV Fluids and Solutions Guide and Cheat Sheet
How to Calculate IV Flow Rate?
- To calculate IV flow rates, the nurse must know the total volume of fluid to be infused and the specific time for the infusion.
- Intravenously administered fluids are prescribed most frequently based on milliliters per hour to be administered. The volume per hour prescribed is administered by setting the flow rate, which is counted in drops per minute.
- There are three commonly used ways on how to indicate flow rates:
- Milliliters per hour (mL/h). Calculated by dividing the total infusion volume by the total infusion time in hours
- Number of drops per one (1) minute (gtts/min). Calculated by multiplying the total infusion volume to the drop factor and then dividing by the total infusion time in minutes.
- Infusion time. Total volume to infuse divided by milliliters per hour being infused.
- Drop factor (sometimes called drip factor). The total number of drops delivered per milliliters of solution. This rate varies by brand and types of infusion sets and are printed on the package of the infusion set.
- Generally, macrodrops have a drop factor of 10, 12, 15, or 20 drops/mL.
- Microdrip sets, on the other hand, have a drop factor of 60 drops/mL.
| FORMULA FOR CALCULATING MILLILITERS PER HOUR (mL/hour) |
|---|
mL/h = \frac{total\ infusion\ volume(mL)}{total\ infusion\ time (h)} EXAMPLE: Your patient needs 2,000 mL of saline IV over 4 hours for a patient with deficient fluid volume. How many milliliters per hour will you set on a controller? Where: Total infusion volume (mL) = 2,000 mL Total infusion time = 4 hours Computation: \frac{2,000\, mL}{4\, hours}= 500\, mL/hour Answer: 500 mL/hour |
| FORMULA FOR CALCULATING DROPS PER MINUTE (gtts/min) |
|---|
Drops\ per\ minute\ (gtts/min) = \frac{Total\ infusion\ volume \times drop\ factor}{total\ time\ of\ infusion\ in\ minutes} EXAMPLE: A patient is receiving 250 mL normal saline IV over 4 hours, using tubing with a drip factor of 10 drops/mL. How many drops per minute should be delivered? Where: Total infusion volume = 250 mL Drop factor = 10 gtts/mL Total infusion time = 4 hours or 240 minutes Calculate: \frac{250 mL \times 10 gtts/mL}{240 minutes} = 10.42 gtts/min Answer: 10 gtts/min (rounded off) Fun fact: gtts is an abbreviation of the latin word “guttae” meaning drops. |
| FORMULA FOR INFUSION TIME (H) |
|---|
infusion\ time\ (hour) = \frac{total\ volume\ to\ infuse (mL)}{milliliters\ per\ hour \ being \ infused (mL/hour)} Example: A patient is ordered to received 1,000 mL of NSS to be administered at 125 mL/hour. How many hours will pass before you change the IV bag? Where: Total volume to infuse = 1,000 mL mL infused per hour = 125 mL/hour Calculate: \frac{1000 mL}{125 mL/hour} = 8 hours Answer: 8 hours |
How to Regulate IV Fluids?
- The following factors affect the infusion rate if an infusion pump is not used:
- Size of the catheter. A catheter with a larger bore allows solution to flow faster.
- Height of the IV bag. The higher the IV bag, the faster the infusion will flow.
- Position of the insertion site. A change in the position of the client’s arm may decrease the flo, while elevation on a pillow may increase flow rate. If the IV is inserted into the antecubital area, the solution can flow freely if the client extends the arm and can be obstructed if the client bends the arm at the elbow.
- Monitoring and regulating the rate of the infusion is a responsibility of the nurse.
- A slower rate is usually necessary for older adults or those who are at risk of fluid overload (e.g., heart disease or client with head injury).
- A faster IV flow rate is therapeutic for patients who have lost large amounts of body fluids and those who are severely dehydrated.
- Never increase the rate of infusion if it is running behind schedule. Check for obstructions and collaborate with primary care providers to determine the patient’s ability to tolerate an increased flow rate.
- Flow rate is regulated by tightening or releasing the IV tubing clamp and counting the drops for 15 seconds then multiplying the number 4 to get drops per minute.
- Sometimes, the IV rate order will say “to keep open” (TKO) or “keep vein open” (KVO). This order does not specify the Milliliters per hour. Generally, KVO is infused at 50 mL/h.
Flow-Control Devices
- Flow-control devices are any manual, mechanical, or electronic infusion device used to regulate the IV flow rate. These devices may include manual flow regulators, elastomeric balloon pumps, and electronic infusion devices.
- Electronic infusion devices (EIDs)
- EIDs are often used in acute care settings and use positive pressure to deliver a preset fluid volume at preset limits.
- They are programmed to regulate the IV flow rate in either drops per minute or milliliters per hour.
- EIDs use gravity to maintain the flow of the IV fluid. They sense the rate and amount of IV fluid.
- An alarm is set off if there is air in the tubing, the bag is empty, or the flow is obstructed. However, the nurse should still conduct regular evaluations of the IV site.
- Multichannel pumps
- Another type of flow-control device that can deliver several medications and fluids (from either bags, bottles, or syringes) at the same time, at multiple rates.
- Multichannel pumps usually have two to four channels with each channel that can be programmed independently.
- Mechanical flow-control devices
- Are nonelectric devices used to regular IV flow rate. These are in-line devices with a manual regulator that controls the amount of fluid to be administered.
- Rotating a dial sets the flow rate.
- Elastomeric infusion pumps
- Are disposable, portable, and nonelectric pumps that are prefilled with medication and connect to the client’s needleless connector to deliver a controlled rate of medication.
General Nursing Considerations
- Monitor for infiltration or irritation. Inspect the insertion site for fluid infiltration. If present, stop the infusion and remove the catheter. Restart the infusion at another site and start supportive treatment by elevating or applying heat to the site.
- Look for signs of infiltration. Infiltration occurs when the IV fluid is not flowing into the client’s vein but into surrounding tissues. Signs of infiltration include swelling or puffiness, coolness, pain at the insertion site, and tenderness in the area.
- Monitor for signs of phlebitis. Phlebitis is the inflammation of the vein. Signs include pain and tenderness, swelling, and warmth in the area. If phlebitis occurs, stop infusion and restart at another site. Do not use the injured vein again.
- Regularly monitor IV flow rate. Monitor IV flow rate regularly (every hour) even if the solution is administered through an IV pump.
- Assess for fluid overload. Regularly assess the patient for signs of fluid overload: increased heart rate, increased respirations, and increased lung congestion.
- Risk for fluid overload. IV flow-control devices should be used for older and pediatric patients when administering IV fluids. These age groups are at risk for complications of fluid overload.
- Proper documentation. Document all findings on the IV flow sheet or in the computer. Including the total amount of fluid administered, and any adverse responses of the client.
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