Basic IV Drip Rates
TOPICS COVERED
1. IV fluids
2. IV drip factors
3. Choosing infusion set tubing
4. Infusion pumps
5. Labeling IVs
6. Calculating basic IV drip rates: milliliters over a number of hours, milliliters per hour (mL/hour), and drops per minute (gtt/minute)
7. Determining hours an IV will run
8. Assessment
9. Adding medications to continuous IVs
10. Intermittent piggyback drip rates
11. Enteral feeding
12. Recording IV intake
Administration of parenteral fluids and medications by the IV (intravenous) route is common medical practice and is a specialty within nursing and health care. Texts such as Plumer’s Principles and Practice of Intravenous Therapy (Lippincott Williams & Wilkins, 2006) present detailed and extensive information. This chapter presents basic knowledge—types of fluids, equipment, calculation of drip rates, and recording intake. Chapter 7 presents rules and calculations for special types of IV orders.
Types of IV Fluids
IV fluids are packaged in sterile plastic bags or glass bottles. It is essential to choose the correct IV fluid to avoid serious fluid and electrolyte imbalance that may occur from infusing the wrong solution. Physicians and healthcare providers order IV fluids and the IV flow rate.
If you have any doubt about the correct IV solution, always double-check with another healthcare professional.
Common abbreviations for IV fluids are listed in Table 6-1.
FIGURE 6-1
Drip chambers for macrodrip and microdrip IV tubing.
Kinds of IV Drip Factors
IV fluids are administered through infusion sets. These consist of plastic tubing attached at one end to the IV bag and at the other end to a needle or catheter inserted into a blood vessel. The top of the infusion set contains a chamber. Sets with a small needle in the chamber are called microdrip because their drops are small. To deliver 1 mL of fluid to the patient/client, 60 drops drip in the drip chamber (60 gtt = 1 mL). All microdrip sets deliver 60 gtt/mL.
Infusion sets without a small needle in the chamber are called macrodrip (Fig. 6-1). Drops per milliliter differ according to the manufacturer. For example, Baxter-Travenol macrodrip sets deliver 10 gtt/mL, so 10 drops drip in the drip chamber (10 gtt = 1 mL); Abbott sets deliver 15 gtt/mL, so 15 drops drip in the drip chamber (15 gtt = 1 mL). The package label states the drops per milliliter (gtt/mL). Sometimes the drop factor is also stated on the top part of the chamber. To calculate IV drip rates, you must know this information.
The tubing for these sets includes a roller clamp (Fig. 6-2A) that you can open or close to regulate the drip rate; use a watch or a clock with a second hand to count the number of drops per minute in the chamber (Fig. 6-2B).
FIGURE 6-2
(A) Roller clamp (B) Timing the IV drip rate. (© B. Proud.) (With permission From Taylor, C., Lillis, C., & LeMone, P. [2004]. Photo atlas of medication administration. Philadelphia, PA: Lippincott Williams & Wilkins, p. 46.)
FIGURE 6-3
Dial-a-Flow device. (Copyright 2010 L. Farmer Photography)
FIGURE 6-4
IV rate is programmed into the infusion pump in milliliters per hour. (With permission from Craven, R., and Himle, C. (2007) Fundamentals of nursing (5th ed). Philadelphia, PA: Lippincott Williams and Wilkins, p. 576.)
The Dial-a-Flow device (sometimes referred to as Dial-a-Flo) is an extension IV tubing that attaches to the primary IV tubing (Fig. 6-3). It is calibrated in milliliters per hour; you “dial” the rate, and the device regulates the flow. The roller clamp must be open all the way. Usually, these devices are not used with an infusion pump. The rate is still an approximate amount, and changes in the patient/client position can affect the flow rate.
Infusion Pumps
Electric infusion pumps also deliver IV fluid. Some are easy to operate; others are more elaborate. You must enter two pieces of information: the total number of milliliters to be infused and the number of milliliters per hour. Pumps used in specialty units also allow you to input the name of the medication, the concentration of the medication, the amount of fluid, and the patient/client’s weight. The infusion rate is set in milliliters per hour, and the pump automatically calculates the dose in milligrams, micrograms etc. There are several manufacturers of IV pumps; some pumps use regular IV tubing, while other pumps use tubing specific to that IV pump. All IV pumps allow you to program the primary IV rate, volume to be infused, secondary IV rate, and total volume that has infused over a period of time. The pump can also calculate the dosage based on weight. Figure 6-4 shows the face of an infusion pump with IV tubing connected.
The tubing factor for an IV infusion pump is 60 gtt/mL; however, the rate is stated and programmed as milliliters per hour.
Labeling IVs
Every IV must be labeled so that any professional can check both the fluid that is infusing and the drip rate. A typical order includes the following information:
• Patient/client name, room, bed number, date, and time
• Order: 500 mL D5W½NS. Rate: 50 mL/hr.
LABEL
Calculating Basic IV Drip Rates
Routine IV orders specify the number of milliliters of fluid and the duration of administration:
EXAMPLE
As mentioned previously, an infusion pump is set in milliliters per hour, so your dosage calculations are in milliliters per hour as well. IV tubing sets infuse at drops per minute, and the infusion rate depends on the drip rate of the tubing used. Although many institutions only use infusion pumps occasionally you will need to calculate and infuse IV fluid using the drip rate calculation.
RULE 
SOLVING IV CALCULATIONS WITH MICRO- AND MACRODRIP TUBING
The terms drop factor, drip factor, gtt factor, and tubing drip factor are all used to explain how many drops per milliliter the tubing delivers. In this text, we will use tubing factor or TF to mean all of these terms.
Calculation
For example, the order is to infuse 120 mL of IV fluid over 60 minutes with a tubing factor of 10 drops per milliliter. The calculation is:
For dimensional analysis, you set up the equation as such:
In this example:
Cancel “mL.” Reduce the fraction. Solve.
Explanation
TF: the tubing drip factor—either microdrip (60 gtt = 1 mL) or macrodrip. Depending on the manufacturer, macrodrip could be 10 gtt = 1 mL, 15 gtt = 1 mL, or 20 gtt = 1 mL.
minutes: the number of minutes, specified in every IV order. If the order reads “hour,” then you convert to minutes by multiplying by 60 (60 minutes = 1 hour).
gtt/minute: the drip factor, calculated to deliver an even flow of fluid over a specified time. To regulate the drip rate, use a second hand on a watch or a clock. If the drip rate is calculated to be 20 gtt/minute, open the clamp and regulate the drip until you reach that amount. Usually, you break this amount down into seconds rather than counting for a full minute. For this example, 20 gtt/minute becomes approximately 5 gtt every 15 seconds (20 gtt divided by 60 = 0.33 gtt every second. multiply 0.33 times 15 = approximately 5 gtt every 15 seconds).
The problems requiring calculation in this text will supply the tubing (or drip) factor. When you’re working in the clinical area, you must read the package label of the IV tubing to identify the drops per milliliter.
Solving IV Calculations Using an Infusion Pump
Infusion pumps are always calculated in milliliters per hour. Here’s how to calculate the example from above, infusing 120 mL of IV fluid over 60 minutes:
The calculation looks like this:
Note that 60 minutes was changed to 1 hour (60 minutes = 1 hour).
After calculating, connect the IV fluids to the infusion pump with the appropriate tubing, set the pump at 120 mL/hour, set the volume for infusion—120 mL, and start the infusion.
Explanation
mL: The physician or healthcare provider will indicate the number of milliliters to be infused in the order.
hours: The number of hours to run depends on the way the order is written. For example:
Alternate Way
Here’s a formula you can use to calculate what rate to set on the infusion pump:
Since the tubing factor is always 60 gtt/mL with infusion pumps, for the calculation “infuse 120 mL of IV fluid over 60 minutes using an infusion pump,” the formula looks like this:
Drip rates are rounded to the nearest whole number unless using an infusion pump that can infuse in tenths or hundredths (i.e., 8.25 mL/hour). Usually, these infusion pumps are used in a specialty setting such as critical care or pediatrics.
Choosing the Infusion Set
Experience will enable you to judge which IV tubing to use. In clinical settings, the guidelines below will help you make your choice. An electric infusion pump poses no problem, because it will deliver the amount programmed. Specialized pumps in neonatal and intensive care units can deliver 1 mL/hour and even less. Specialized syringe pumps also can deliver less than 1 mL/hour.
When an IV pump is not available, consider these guidelines:
Use microdrip when
• the IV is to be administered over a long period
• a small amount of fluid is to be infused
• the macrodrops per minute are too few (Without an infusion pump, IV fluids flow by gravity. Blood flowing in the vein exerts a pressure. If the IV is too slow, the pressure of the blood in the vein may back up into the tubing, where it may clot and cause the IV to stop infusing.)
Use macrodrip when
• the order specifies a large amount of fluid over a short time
• the microdrips per minute are too many, and counting the drip rate becomes to difficult
EXAMPLE
Order: 1000 mL D5W IV 8 AM–8 PM
Available: an infusion pump
8 AM to 8 PM indicates that the IV will run for 12 hours. The infusion pump regulates the rate in milliliters per hour.
Label the IV.
Set the pump as follows:
Total volume to infuse: 1000 mL
mL/hour: 83 (Dimensional Analysis: use the same equation, no conversion factor is needed)
Order: 500 mL NS IV 12 NOON–4 PM
Available: microdrip at 60 gtt/mL; macrodrip at 20 gtt/mL
The IV will run 4 hours or 240 minutes (4 × 60 minutes). Because no pump is available, the nurse must choose the drip factor. Solve for both drip factors and choose one. Round to the nearest whole number.
MACRODRIP
Dimensional Analysis: Use the conversion
Cancel “mL” and “hour.” Reduce the fraction. Solve.
Macrodrip at 42 gtt/minute.
MICRODRIP
Dimensional Analysis:
Microdrip at 125 gtt/minute.
Answers are macrodrip at 42 gtt/minute and microdrip at 125 gtt/min. Choose one.
Label the IV.
Set the drip rate.
Order: 500 mL D5W IV KVO for 24° (KVO stands for “keep vein open”. It usually is an IV rate that keeps fluids infusing through a vein. TKO (too keep open) is another abbreviation with the same meaning).
Available: microdrip at 60 gtt/mL; macrodrip 10 gtt/mL
Because no pump is available, choose the IV set. The IV will run 24 hours or 1440 minutes (24 × 60 minutes). Work out the problem for micro- and macrodrip and make a nursing judgment about which tubing to use. Round to the nearest whole number.
MACRODRIP
Dimensional Analysis:
Macrodrip at 3 gtt/minute.
MICRODRIP
Dimensional Analysis:
Microdrip at 21 gtt/minute.
A 3-gtt/minute macrodrip is too slow. Choose microdrip. (See the explanation for choosing the infusion set on page 204.)
Label the IV.
Select a microdrip infusion set.
Set the drip rate at 21 gtt/minute.
Calculation of Drip Factors
Calculate the drip factor for the following IV orders given in milliliters per hour or drops per minute. Answers are given at the end of the chapter. Round to the nearest whole number.
1. Order: | 150 mL D5W 0.33NS IV q8h |
Available: | infusion pump |
2. Order: | 250 mL D5W; run at 25 mL/hour |
Available: | infusion pump |
3. Order: | 1000 mL D5NS; run 100 mL/hour |
Available: | macrodrip (20 gtt/mL); microdrip (60 gtt/mL) |
4. Order: | 180 mL D5½NS 12 NOON–6 PM |
Available: | macrodrip (10 gtt/mL); microdrip (60 gtt/mL) |
5. Order: | 1000 mL D5W 0.45NS IV 4 PM–12 MIDNIGHT |
Available: | macrodrip (15 gtt/mL); microdrip (60 gtt/mL) |
6. Order: | 250 mL D5W IV q8h |
Available: | infusion pump |
7. Order: | 500 mL NS IV over 2 hours |
Available: | infusion pump |
8. Order: | 1000 mL D5NS IV 4 AM–4 PM |
Available: | macrodrip (15 gtt/mL); microdrip (60 gtt/mL) |
9. Order: | 1000 mL D5W 0.45 NS IV; run 150 mL/hour |
Available: | macrodrip (10 gtt/mL); microdrip (60 gtt/mL) |
10. Order: | 150 mL 0.9 NS IV; over 1 hour |
Available: | macrodrip (20 gtt/mL); microdrip (60 gtt/mL) |
Determining Hours an IV Will Run
Knowing how to calculate approximately how long an IV will last helps you to know when to prepare the next IV, or to be aware if the IV is infusing too fast or too slow.
EXAMPLE
Order: 500 mL NS IV; infuse at 75 mL/hour
The IV will last approximately 6.7 hours. How many hours and minutes will this be? Since there are 60 minutes in an hour, take 0.7 and multiply by 60, which equals 42 minutes.
What time will the IV be complete? If the IV bag is hung at, say, 8 AM, then add the hours and minutes to calculate when the IV should be complete: 2:42 PM (6 hours and 42 minutes added to 8 AM).
EXAMPLE
Order: 1000 mL ½ NS IV 8 AM–8 PM
No math necessary; 8 AM–8 PM = 12 hours
The IV will last 12 hours.
Order: aminophylline 500 mg in 500 mL D5W IV at 50 mL/hour
The IV will last 10 hours.
Start the infusion at 10 AM. When will the IV infusion be complete?
10 AM + 10 hours = 8 PM
The infusion will be complete at 8 PM.
FINE POINTS
In this example, the amount of the drug (aminophylline) is not needed for the calculation of IV rate.
SELF-TEST 2
IV Infusions—Hours
Calculate the hours that the following IV orders will run. Answers are given at the end of this chapter. Convert to hours and minutes if applicable.
1. Order: 250 mL D5 ½ NS IV at 30 mL/hour
2. Order: LR 500 mL IV run at 60 mL/hour
3. Order: 1000 mL D5NS IV 4 PM–2 AM
4. Order: 1000 mL D5W IV KVO 24 hours
5. Order: 500 mL D5⅓NS at 70 mL/hour
6. Order: 500 mL D5W IV at 50 mL/hour
7. Order: LR 1000 mL IV 10 hours Start the IV at 9 AM. When will it be finished?
8. Order: 250 mL NS IV at 100 mL/hour Start the IV at 1 PM. When will it be finished?
9. Order: 1000 mL NS IV 12 NOON–6 PM
10. Order: 500 mL NS IV over 5 hours
Assessment
Many factors may interfere with the drip rate. When you are not using an infusion pump, gravity will cause the IV to vary from its starting rate; you will need to observe and assess the infusion and IV site frequently. You’ll need to monitor other conditions as well. As the amount of fluid decreases in the IV bag, pressure changes occur—and they, too, may affect the rate. The patient/client’s movements can kink the tube and shut off the flow; they can change the position of the needle or catheter in the vein. The needle can become lodged against the side of the blood vessel, thereby altering the flow, or it may be forced out of the vessel, allowing fluid to enter the tissues (infiltration). (Signs of possible infiltration are swelling, pain, coolness, or pallor at the insertion site. If you notice any of these signs, discontinue the IV and start a new one at another insertion site.)
Infusion pumps have an alarm system that beeps to alert you when the rate cannot be maintained or when the infusion is nearly finished. Be sure to check the infusion pump frequently, and know how to troubleshoot the various alarms.
Adding Medications to IVs
When a continuous IV order includes a medication, generally this medication arrives already premixed in the infusion bag or the pharmacist adds it on site. In some institutions, you, the nurse, add the medication to the IV and determine the rate of flow. If the task falls to you, first calculate how much of the medication to add to the IV fluids and then calculate the drip rate.
EXAMPLE
Order: 1000 mL D5W with 20 mEq KCl IV 10 AM–10 PM
Available: vial of KCl 40 mEq/20 mL, microdrip (60 gtt/minute), macrodrip (20 gtt/minute)
Calculate how many milliliters to add to the IV fluids.
Add 10 mL KCl to the IV bag.
Choose the tubing. The IV will run 12 hours.
For macrodrip: 
For microdrip: 
Choose either drip rate.
Label the IV.
Order: aminophylline 250 mg in 250 mL D5W IV; run at 50 mL/hour for 1 hour.
Available: ampule of aminophylline labeled 1 g in 10 mL; Buretrol that delivers 60 gtt/mL (microdrip). See Figure 6-5.
The ampule of aminophylline has 1 g in 10 mL. This is equivalent to 1000 mg in 10 mL. You want 250 mg.
Calculate how many milliliters to add to the IV fluids.
Draw up 2.5 mL and inject it into 250 mL D5W. You have 250 mg aminophylline in 250 mL D5W. Label the bag.
You want 50 mL/hour, and you have a Buretrol 60 gtt/mL. Open the Buretrol device, and drip in 50 mL. You will run this amount over 1 hour because that’s what the order specified.
Label the IV: Rate, 50 mL/hour or 50 gtt/minute
FINE POINTS
The Buretrol is microdrip. No calculation is needed:
mL/hour = gtt/minute
FIGURE 6-5
A Buretrol is an IV delivery system with tubing and a chamber that can hold 150 mL delivered as microdrip (1 mL = 60 drops). (This device is sometimes referred to as a Volutrol.) The top of the Buretrol has a port so that a reservoir of fluid can be added. The Buretrol is a volume control because no more than 150 mL can be infused at one time.
IV Infusion Rates
Calculate how much medication is needed (if applicable) and the infusion rate for the following orders. Answers are given at the end of the chapter. Round to the nearest whole number.
1. Order: | 500 mL D5W IV with vitamin C 500 mg at 60 mL/hour |
Available: | ampule of vitamin C labeled 500 mg/2 mL; microdrip tubing at 60 gtt/mL |
2. Order: | 250 mg Solu-Cortef (hydrocortisone sodium succinate) in 1000 mL D5W 8 AM–12 MIDNIGHT |
Available: | vial of hydrocortisone sodium succinate labeled 250 mg with a 2-mL diluent; microdrip tubing |
3. Order: | aminophylline 250 mg in 250 mL D5W IV; run 50 mL/hour |
Available: | infusion pump, vial of aminophylline labeled 500 mg/10 mL |
4. Order: | 250 mL D5½NS with KCl 10 mEq IV 12 NOON–6 PM |
Available: | microdrip tubing, vial of potassium chloride labeled 20 mEq/10 mL |
Medications for Intermittent IV Administration
Some IV medications are administered not continuously but only intermittently, such as every 4, 6, or 8 hours. This route is termed intravenous piggyback or (IVPB) (Fig. 6-6). The term admixture refers to the premixed IVPB.
Most of these drugs are prepared in powder form. The manufacturer specifies the type and amount of diluent needed to reconstitute the drug; later, you, the nurse, connect the IVPB (containing the reconstituted drug) by IV tubing to the main IV line. Some IVPB medications come premixed from the manufacturer. For other medications, the institutional pharmacy may reconstitute and prepare IVPB solutions in a sterile environment using a laminar flow hood. This procedure saves nursing time, because when you are ready to administer the drugs, they have already been prepared, labeled, and screened for incompatibilities. Nevertheless, the nurse still bears considerable responsibility: You must check the diluent and volume. You must also check the dose and the expiration date of the reconstituted solution; note whether the IVPB should be refrigerated before use or whether it can remain at room temperature until hung. Finally, you must calculate the drip rate and record this information on the IVPB label before hanging the bag.
FIGURE 6-6
A primary IV line (right) and an IVPB (or secondary) line (left). Fluid flows continuously through the primary line into the patient/client’s vein. At timed intervals, medication placed in an IVPB is attached by tubing to the primary IV for delivery to the patient/client. The primary fluid is lowered and the IVPB fluid flows. After the IVPB has infused, the primary fluid begins infusing again. An IV infusion pump may also be used, where medication in the IVPB is infused through the pump.
The physician or healthcare provider may write a detailed order, such as “Vancomycin 0.5 g IVPB in 100 mL D5W over 1 hour.” More often, however, the physician or healthcare provider writes only the drug, route, and time interval, relying on you to research the manufacturer’s directions for the amount and type of diluent and the time for the infusion to run (e.g., Order: cefazolin 1 g IVPB q6h).
Explanation
To solve IVPB problems, you use a calculation much like the one you used for the IV:
mL: The label or the package insert will state the type and amount of diluent.
TF: The tubing for IVPB is referred to as a secondary administration set and has a macrodrip factor. It is shorter than main line IV tubing. In the clinical setting, check the label for the tubing drip factor.
Minutes: The manufacturer may or may not indicate the number of minutes needed for the IVPB medication to be infused. When the number is not given, follow this general rule for adults: allow 30 minutes for every 50 mL of solution.
EXAMPLE
Order: Ancef (cefazolin) 1 g IVPB q6h
Supply: package insert IVPB dilution of cefazolin sodium. Reconstitute with 50 to 100 mL of sodium chloride injection or other solution listed under administration. Other solutions listed include D5W, D10W, D5LR, and D5NS.
Use a 50-mL bag of D5W. It is the most common IVPB diluent. No time for infusion is given in the directions for IVPB; so use 30 minutes for 50 mL.
Here’s the calculation:
Dimensional Analysis:
Before hanging the IVPB, reconstitute the drug. You have a vial of powder labeled 1 g, and you need the whole amount. You have a 50-mL bag of D5W, and you need that whole amount as well. To mix the powder and the diluent, use a reconstitution device—a sterile implement containing two needles or a needleless device that connects the vial and the 50-mL bag. With this device, you can dilute the powder and place it in the IV bag without using a syringe (Fig. 6-7). Some manufacturers now enclose a reconstitution device with the IV bag. Once the powder is reconstituted, label the IV bag.
The order is q6h, and generally the administration times are 6 AM, 12 NOON, 6 PM, 12 MIDNIGHT. The time of infusion is 30 minutes, and for this label, it will run from 12 NOON to 12:30 PM.
Rather than spending time looking through package inserts for directions, check the concise information in a drug reference such as Lippincott’s Nursing Drug Guide or a drug information Web site that your hospital or institution provides.
MEDICATION ADDED
Patient/Client Chelsea Robertson | Room 1503 |
Medication cefazolin 1 g | Flow Rate 17 gtt/minute |
Base Solution 50 mL D5W | Initials RT |
| Date, Time 6/14, 12 PM |
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