• Calculate infusion flow rates for the following units of measurement: mg per mL, mg per hr, mg per min, mcg per mL, mcg per hr, mcg per min, mcg per kg, mcg per kg per hr, mcg per kg per min, mg per kg, mg per kg per hr, mg per kg per min, and mEq per hr. • Confirm IV medication orders with safe dose range (SDR) criteria. • Calculate schedules for manual IV direct push medications. • Calculate the parameters of flow rates for titrated IV infusions. • State the difference between central venous lines and peripheral venous lines. • Calculate the calories in selected IV solutions. • State the general purpose, contents, and types of hyperalimentation (PN) infusions. • Identify patient safety issues for the administration of IV medications, including PN infusions. Chapter 9 focused on prepared IV solutions that required simple flow rate calculations. This chapter emphasizes more complex dose-based flow rate calculations for a variety of medicated IV solutions for peripheral access sites. The principles of the equation setup are the same as in earlier chapters. Parenteral Nutrition (PN) (AKA, “Hyperalimentation,” “Hyperal”) Parenteral nutrition (PN) refers to an IV caloric infusion of nutrients, vitamins, minerals, and electrolytes through a central (CPN) or peripheral (PPN) venous line. Contents and amounts are prescribed on an individual basis. Infusion Access Sites: Central and Peripheral Venous Central venous sites are large blood volume sites (such as the superior vena cava and right atrium) that can be accessed by catheter from large veins (such as the jugular) or surgically accessed chest veins. They can also be accessed from peripherally inserted central catheters (PICC), which are less invasive and threaded to the superior vena cava–right atrial junction from a peripheral vein. The central venous sites provide rapid dilution of concentrated solutions such as TPN and medications and are more suitable for longer term therapy and more concentrated solutions than smaller peripheral veins. IV Flush (SAS) (SASH) Technique that maintains patency of IV sites used before and after infusion of medications and for periodic maintenance. Saline solution or less frequently, low-dose heparin solution is injected through infusion ports in accordance with agency protocols for milliliter amounts for each type of flush solution and the equipment being flushed. The longer the line, the more solution must be used. Also used to clear lines of solutions before administering a potentially incompatible solution. SAS means “saline, administer drug, saline flush.” SASH means “saline, administer drug, saline, heparin flush.” Kilocalorie (Kcal) Metric measurement, unit of energy, necessary to raise the temperature of 1 kg of water by 1° C. Commonly described as “calorie,” even though there are 1000 calories in a kilocalorie, as the metric prefix indicates. The “Calories” on food labels are actually kilocalories. Peak and Trough Levels Serum levels of drugs derived from blood samples drawn 30 minutes before the next dose is due (trough) and 30 minutes after administration (peak) for IV drugs and 1-2 hours after oral drugs (peak). Guides the prescriber for effective dosing and avoidance of toxicity or damage to renal function. Nurse must label specimen with peak or trough, exact time drawn, and time and dose of last medication infusion. Certain drugs, such as aminophylline, the IV bronchodilator used for severe asthma, have widely varying rates of individual absorption and necessitate peak and trough measurements. Titrated Medication Flexible drug order for dose adjustments to achieve desired therapeutic result, such as a specific urinary output, systolic or diastolic blood pressure, or glucose level (e.g., “dobutamine 2-8 mg per kg per min IV infusion. Increase or lower by 1-2 mg every 30 minutes to achieve/maintain systolic pressure between 90 and 110 degrees). Administered and adjusted by experienced registered nurses. Vascular Implanted Devices Vascular Access Devices (VAD) Surgically implanted subcutaneous self-access sealing injection ports that can tolerate repeated injections with a special Huber needle. The port is attached to a catheter threaded to the target site, most commonly the subclavian vein. Saves the patient the discomfort of multiple injections. RAPID PRACTICE 10-2 Basic Intravenous Calculations Review Estimated completion time: 20–25 minutes Answers on page 546 1. Ordered: 2 mL per min. Need to know: mL per hr. 2. Ordered: 120 mL per hr. Need to know: mL per min to nearest tenth of a mL. 3. Ordered: 4 mg per min. Need to know: mg per hr. 4. Ordered: 60 mg per hr. Need to know: mg per minute. 5. Ordered: 2 mg per kg per min. Weight: 10 kg. Need to know: mg per minute. 1. What are four conversion factors that may be needed for IV infusion calculations? (Give a brief answer.) _________________________________________________________________________ Three factors must be entered in the medication equation to determine mL per hour flow rates: Evaluation: The equation is balanced. Only mL per hr remain. 1. What are three factors that need to be entered in the equation in order to calculate medicated IV infusion rates in mL per hr? (Use one- or two-word answers.) _________________________________________________________________________ Ordered: Drug Y, 100 mcg per min. Available: Drug Y, 400 mg per 250 mL. Evaluation: The equation is balanced. Only mL per hr remain. RAPID PRACTICE 10-4 Calculating IV Flow Rates That Require Two Conversion Factors Estimated completion time: 20-25 minutes Answers on page 548 1. Ordered: Drug Y, IV infusion 200 mcg per min. Available: Drug Y, 250 mg per 1000 mL D5W. 2. Ordered: Drug Y, IV infusion 75 mcg per min. Available: Drug Y, 10 mg per 100 mL NS.* 3. Ordered: Drug Y, IV infusion 5 mg per min. Available: Drug Y, 1 g per 200 mL LRS. 4. Ordered: Drug Y, IV infusion 200 mcg per min. Available: Drug Y, 500 mg per 250 mL D5W. 5. Ordered: Drug Y, IV infusion 1.5 mg per min. Available: Drug Y, 2 g per 200 mL NS. 1. Why are two conversion factors needed in problems 1 and 2? Which factors are they? _________________________________________________________________________ *NS solution is 0.9% NaCl solution. Refer to Chapter 9. Any concentration other than 0.9% is stated, e.g., 0.45% NaCl ( 1. Identify the desired answer units. 2. Calculate the ordered dose based on the requested units of weight. 3. Enter the drug concentration available, the ordered dose, and any needed conversion formulas in a DA equation to obtain the desired answer. Calculate the total drug ordered using the patient’s body weight in kilograms. How many total micrograms per minute are ordered? Estimated dose in micrograms: (2 mg × 50 kg) = 100 mcg total dose per minute. The final equation will be written like this: The example that follows illustrates a one-step equation for IV weight-based orders. What flow rate will be set on the IV pump the nearest tenth of a mL? Conversion factors: 60 minutes = 1 hr; 1000 mcg = 1 mg.
Advanced Intravenous Calculations
Introduction
The nurse must always check for compatibilities and incompatibilities before mixing and or administering medications and solutions. It must be assumed that IV solutions and medications, including diluents, are incompatible unless the literature states otherwise. With the great increase in available medications, the responsibility to protect the patient increases.
Filters Used in some IV medication lines to prevent contaminants, particles, and clots from reaching patient circulation. Liquids can pass through the filter. Specific guidelines for use and nonuse and filter size must be checked with agency and manufacturer guidelines prior to administration of medications. The smaller the size filter, the finer the filter. Blood administration sets are supplied with a clot filter, and other filters may be added for specific purposes, depending on the age of the blood product. Filters are not routinely used for IV infusions.
Equation Setups for Advanced Intravenous Calculations
Conversion Factors That May Be Needed for Intravenous Infusion Calculations*
Conversion Factors
Purpose
60 minutes = 1 hour
Often needed to obtain milliliters or medication dose per hour, this formula also may be needed to verify how much drug per minute or volume per minute is being infused. For example:
Ordered: Drug Y, 1 mg per min. Question: How many milligrams or milliliters per hour will be infused?
1000 mg = 1 g
Needed for conversion when the drug units supplied do not match the drug
1000 mcg = 1 mg
units ordered. For example:
Ordered: Drug Y, 2 mcg per min. Supplied: Drug Y, 500 mg.
1000 mL = 1 L
Needed to convert liters to milliliters for IV flow rate calculations. IV flow rates are delivered in milliliters. Ordered: 1 L q8h.1 L = 1000 mL.1000 mL ÷ 8 = 125 mL per hr.
2.2 lb = 1 kg
Occasionally needed to calculate the dose ordered when the dose is based on weight and the weight in pounds is known and that in kilograms is not. For example:
Ordered: Drug Y, 2 mg per kg per min. Weight: 50 lb.
Calculating Medicated Intravenous Flow Rates That Require One Conversion Factor
2 mg per min
5 mcg per min
3 units per min
4 mg per hr
3 mcg per hr
10 mEq per hr
0.3 mg per kg per min
1 mcg per kg per min
05 milliUnits per min
250 mg drug per 500 mL D5W
500 mg drug per 250 mL NS
100 mg drug per 250 mL D5W
250 mg drug per 1000 mL NS
100 mg drug per 50 mL NS
1 g drug per 1000 mL D5W
One conversion factor is needed. Because the drug ordered and the drug supplied are in the same terms, milligrams, a minutes to hours conversion is the only factor needed.
The drug concentration is entered as one factor. Reduction and cancellation makes the math easy.
Calculating Intravenous Flow Rates That Require Two Conversion Factors
If a drug is ordered in mcg per min but supplied in mg per ml or ordered in mg per min but supplied in g per ml, two conversion factors must be included in the equation:
The drug ordered and the drug supplied must be converted to the same terms.
NS).
Calculating Flow Rates for Weight-Based Doses
Step 2, calculating the ordered dose based on weight, is the only additional step compared to the problems in Rapid Practice 10-4.
Calculating the total dose ordered for weight-based orders: micrograms and milligrams per kilogram
Ordered: dopamine 2 mcg per kg per min IV. Patient’s weight: 50 kg.
Calculating the flow rate in milliliters per hour (mL per hr) for weight-based orders
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Advanced Intravenous Calculations
Note how the 2 mcg per kg per minute will always set up with the kg per minute(s) in the accompanying denominator in this kind of order that contains 3 units (e.g., 5 mg per kg per hour or 10 mcg per kg per hr).
Ordered: Dopamine 2 mcg per kg per min. On hand: An IV of Dopamine 200 mg in 250 mL of D5W. Patient’s weight: 60 kg.
