Dosage calculation
Celsius=
(degrees Fahrenheit-32) x 5/9
Celsius freezing and boiling point
0 degrees Celsius= freezing 100 degress Celsius= boiling
Deci Centi Milli Micro Nano
0.1 0.01 0.001 0.000001 0.000000001
Lean Body Weight
Another formula is used to estimate LBW, the weight of bone muscle and organs without body fat. The formula is not commonly used because of the possibility of underdosing in obese patients. Male: (0.32810 x (weight in kilograms) + (0.33929 x height in centimeters)) — 29.5336 (over age 16) Female: (0.29569 x (weight in kilograms) + (0.41813 x height in centimeters)) — 43.2933 (over age 30)
Calculating Infusion Rates of A Drug For Specific Body Weight Per Unit Time
Calculate the infusion rate of medication for a specific body weight per unit time using the same methods described previously in this module. First, calculate the concentration of titrated medication in 1 mL of solution and then multiply the body weight by the dosage per kilogram per minute to determine the number of milliliters to be infused per hour. Medication order: dopamine 600 mg in 500 mL of D5W. Infuse at 10 mcg/kg/min Patient weight: 150 pounds Titrated medication available: 600 mg/500 mL = 600,000 mcg/500 mL = 1200 mcg/mL
Basic Formula
D/H x V= amount to give
Fingertip unit (FTU)
Face and neck: 2 1/2 FTU's Trunk: 14 FTU's (front and back) Arm: 3 FTU's Hand: 1 FTU Groin: 1 FTU Leg: 6 FTU's Foot: 2 FTU's
Fractional Equation
H/V=D/X
Forms of Parental Medication
Parenteral medications come in two preparations: liquids and powder. The preparations of liquid medications are available in ampules, vials, mix-o-vials, and prefilled syringes. Powders need reconstituting prior to administration. Let's look at each of these preparations and the procedure for drawing up medication with each of these parenteral medications: Ampules Vials Mix-o-vials Prefilled syringes Powders
Four types of insulin:
Rapid-acting insulins Fast-acting insulins Intermediate-acting insulins Long-acting insulins
Rounding off rule
Since calculators are used for working problems, round off at the final answer and not the steps in between. For BSA problems, round off answers to the nearest hundredth.
Parenteral medications are given by four routes:
Subcutaneous (SubQ) Intradermal (ID) Intramuscular (IM) Intravenous (IV)
Total dosage of medication infused over time
There are times when a nurse may need to calculate the total dosage of a medication administered over time. These times include: when a medication is discontinued, when a therapeutic level is not achieved, and when a toxic effect or an adverse reaction occurs.
Tips of syringes
There are two different tips to a syringe. One tip is known as a Luer-Lok, which has a needle designed to twist and lock on the syringe. The other is a plain tip, (or slip tip) which has a needle that is pushed on. In larger syringes that are used to deliver irrigation solution, the tip is referred to as a catheter tip.
Combination Insulin
There is another form of insulin used for the diabetic patient. This insulin is called combination insulin. The combination insulin is supplied in 70/30 U-100 and 50/50 U-100. In the 70/30 insulin this means that there is 70% of Humulin N insulin and 30% of regular insulin in 1 unit. In the 50/50 insulin this means that there is 50% Humulin N insulin and 30% regular insulin in 1 unit.
Dimensional Analysis (DA)
V/H x C (H)/C(D) x D/1
BMI
Weight in pounds/(height in inches) (height in inches) x 703
enteral administration
When the patient cannot take food or fluids orally, enteral administration of nutrition and medication is utilized. Enteral preparations are administered through a feeding tube that is inserted through the nose (nasogastric), mouth (orogastric), surgically created opening in the stomach (gastrostomy), or surgically created opening in the jejunum.
Infusion pump method
amount of fluid/ hours to administer= mL/hr
Syringes
available in several sizes
Rapid-acting insulin
become effective within 5 to 15 minutes and last 3 to 5 hours
a _________________________ assay is used when there is a drug in which the chemical composition is difficult to determine
biological
medications primarily administered by inhalation:
bronchodilators glucocorticoids mucolytics
two types of nasogastric tubes:
flexible small-bore tube that has a small diameter (4-8 Fr) and the rigid large bore tube with a larger diameter (10-18 Fr)
long-term enteral feeding
gastrostomy and jejunostomy routes -require a surgical procedure for insertion
Emulsion
has small droplets of oil in water or small amounts of water in oil. an example of an emission would be would be mineral or castor oil
topically applied medications:
include lotions, creams, and ointments
Inserted medications:
include rectal suppositories
instilled medication
include: -nasal sprays and drops
ear drops
instilled into the ear canal
if the first roman numeral is less than the following numerals, then SUBTRACT
iv= 4 ix= 9
k h d m d c m
length per meter
large bore nasogastric tube
less likely to clog than small bore tubes
units
measures the potency of a drug through the use of a biological assay
Milliequivalents (mEq)
measures the strength of an ion concentration
eye drops: pupil dilators
medications instilled prior to eye examinations to dilate the pupil
eye drops: operative medications
medications instilled prior to or at the time of completion of eye surgery
eye drops: moisturizers
medications instilled prior to surgery to help maintain moisture to the eye during surgery, when the natural blinking reflex is compromised
mouth and throat: analgesics
medications that decrease pain sensation
mouth and throat: antiseptics
medications that prevent or arrest the growth of microorganisms
suppositories: antiemetics
medications used to decrease nausea when patient cannot take anything by mouth
suppositories: stool softeners
medications used to soften stool
suppositories: laxatives
medications used to stimulate peristalsis to assist in defacation
ear drops: antibiotics
medications used to treat infections (particularly fungal infections)
smaller to larger
move the decimal place to the left
narcotic orders are _______ automatically refilled
not
proper fraction
numerator is less than the denominator ex) 1/2, 1/3
dividend
the number divided
divisor
the number divided by
Needle length:
varies from 3/8 inch to 2 inches -when choosing the needle length nurse must consider the patient and amount of fatty tissue
the most common types of medications used for nasal installation are:
vasoconstrictors glucocorticoids
k h d L d c m m
volume per Liter
Percutaneous medication includes:
-medications inhaled into the lungs -medications applied to the eye, ear, nose, vagina, or rectum -mouthwashes -lotions and creams applied to the skin
Types of inhalation methods of medication administration can be divided into four groups:
-metered dose inhalers (MDI) -metered dose inhalers with spacers -dry powder inhalers -nebulizers
Components of a drug order
-name of a patient -date and time the order was written -drug name -drug dosage -route of administration -frequency of administration -physician or health care providers signature
I V X L C
1 5 10 50 100
1.25=
1 25/100
2.54 cm=
1 inch
micrograms and nanograms are changed by
1,000 not 10 like the rest
Kilo Hecto Deka
1000 100 10
1 unit=
1000 milliunits
MUST MEMORIZE
1000 ml=L= 1L= 1qt= 32 oz
1 foot=
12 inches
1 mL=
15 drops
Range of needle gauges:
18 to 26
IMPORTANT
1L= 32 oz 1 oz= 30 mL 1 inch= 2.54 cm
8 0z=
240 mL
1 ounce (oz)=
30 mL
Liquid metric and household conversions
30 mL= 1oz= 2T=6t 15 mL= 1/2oz= 1T= 3t 1000mL= 1L= 1qt= 32oz 5 ml= 1t
MUST MEMORIZE
30 ml= 1 oz= 2T= 6t
Fahrenheit freezing and boiling point
32 degrees Fahrenheit= freezing 212 degrees Fahrenheit= boiling
1000 ml= 1 L=1qt=
32 oz
1L=
32 oz
Calculating Accuracy of Dilution Parameters Cont'd
A three-step process is used to determine whether the orders for diluting a pediatric intravenous infusion will deliver the amount of medication ordered at the ordered rate (volume of intravenous solution per unit time). Step 1 Calculate the dose of medication to be infused each hour. First, calculate the dose to be infused per minute: Patient weight in kilograms (kg) X dose/kg/min = dose/min Then, calculate the dose to be infused per hour: Dose/min X 60 min/hr = dose/hr Step 2 Calculate the concentration of the solution that will deliver the dose per hour (from Step 1) at the ordered volume per hour: Image Description Step 3 Determine the accuracy of the dilution order: Does the answer in Step 2 match the dilution order (concentration of solution = dilution order)? Use the ratio and proportion method to determine this
Adjusted Body Weight
ABW is used in the dosing of some medications in obese patients and pregnant women. Adjusted body weight is better for nutritional assessment of obese individuals because it prevents overfeeding. Here are the formulas for adults: Male: IBW + 0.4 (Actual body weight — IBW) = ABW Female: IBW + 0.4 (Actual body weight — IBW) = ABW
Body Surface Area
Although not commonly used, BSA is the most accurate way to calculate drug dosages because the correct dosage is more proportional to the surface area of the body. BSA is commonly used in chemotherapy and in some drug dosages for infants and children. Hospital pharmacies commonly use sophisticated computer programs for calculating BSA (using the square root method) and then prepare the medication dose before sending it to the nursing unit for administration. This has become commonplace because of the extremely toxic nature of chemotherapeutic drugs and the grave outcome that could be caused by a miscalculation. Now that calculators are readily available, the square root formula is easier to calculate than the long hand version. Errors can be made with calculators too; therefore a BSA nomogram can prove useful to verify answers. Follow institutional policy regarding BSA methods of calculation.
Fluid Boluses
An IV fluid bolus is the infusion of a large volume of IV fluid over a short period of time. An IV fluid bolus may be used before induction of anesthesia, before administration of a tocolytic drug, or to replace fluid lost through the use of nasogastric suction or other means. A fluid bolus is administered with the use of an electronic infusion pump and given at the rate ordered by the health care provider.
Insulin syringes
An insulin syringe is calibrated by units; 100 units equal 1 mL. Insulin syringes are available in three different sizes: Lo-Dose, ½ mL, and 1 mL. Each is calibrated the same way, wherein 100 units equal 1 mL. Insulin syringes come with permanently attached needles. The needles of insulin syringes cannot be removed. Insulin is measured in USP units. Insulin is manufactured in multi-dose vials of 100 units per milliliter. There are three main syringes that are used to measure and administer insulin. The first syringe is the Lo-Dose syringe. This syringe can be either 50 units in 0.5 mL total volume or 30 units in 0.3 mL total volume. Each calibration on these syringes is 1 unit. When smaller doses of insulin are to be given, the smaller the syringe, the more accurately the dose is measured. The second syringe designed to administer insulin is the single-scale 1-mL syringe. This syringe is calibrated in 2 unit increments. This syringe is ideal for the patient with vision problems. The third syringe is the 1-mL double-scale syringe. This syringe is marked on one side in even calibrations (10, 20, 30, 40, etc.) and with odd calibrations on the opposite side (5, 15, 25, 35, etc.). To avoid confusion, use the odd scale for odd doses, i.e., 17 units and the even scale for even doses, i.e., 20 units. Most insulin syringes have a permanently attached needle, only certain brands of the 1-mL syringe are available with a detachable needle
Preparing a Weaker Solution from a Stronger Solution
At times, the solution that is available will be a stronger/higher percent concentration than the solution ordered. The ratio and proportion method or the fractional equation method can be used to calculate the volume in these situations. The equations used for these two methods are as follows: Ratio and Proportion Method Desired % : Available % :: Desired volume : Known volume
Methods of calculation
Basic formula (BF) Ratio and proportion (RP) Fractional equation (FE) Dimensional analysis (DA)
Insulin infusion pumps
Continuous Subcutaneous Insulin Infusion (CSII) pumps are available to diabetic patients and consist of a small battery-powered infusion device that can: infuse insulin at a basal rate (set rate) of units per hour. deliver a bolus of insulin to cover meals. change delivery rates of insulin during specific times of the day. override the set rate to compensate for additional activity. The CSII pump has become an integral option in diabetic patients' insulin therapy. The insulin pump system consists of the insulin pump, an insulin reservoir, plastic tubing, and an insertion set. The insulin reservoir holds 150 to 300 units of rapid- or fast-acting insulin, which is held in the insulin pump. The plastic tubing is attached to a metal or plastic needle and placed subcutaneously by the patient. The needle can be inserted into the abdomen, upper thigh, or upper arm and is changed every 2 to 3 days. A glucose sensor device can be used to check glucose levels. This sensor is separate from the insulin pump and is attached separately on the abdomen. The glucose sensor transmits to the insulin pump every 5 minutes and will alarm if the glucose level deviates from the preset alarm warnings for high or low glucose levels. Implanted insulin pumps are surgically implanted in the abdomen and deliver a basal infusion and bolus doses with meals either intravenously or intraperitoneally. With implantable insulin pumps, there are fewer hypoglycemic reactions and blood glucose levels are mostly controlled.
Infusion Rate Based on Concentration and Volume of Medication per Unit of Time
Determining the rate of infusion of a titrated medication on the basis of concentration of medication in solution and volume per unit time requires consideration of three variables: The volume of solution (milliliters) to be administered over time The concentration of medication in the solution (number of milliunits, units, milligrams, or micrograms per 1 mL of solution) to be administered over time The unit of time (hour or minute) over which the volume or dose of solution is to be infused Potent medications have specific units of time over which they are to be administered. For some titrated medications such as heparin, the dose per minute is not as important as the dose per hour. For other titrated medications such as potent IV vasoactive medications, the dose per minute is the most important factor and is used in calculating the infusion rate. The health care provider's order for a titrated medication must include the concentration of medication and the rate of infusion (volume of solution or dose of medication per unit of time).
Body Weight
Dosages based on body weight are generally measured in milligrams per kilogram (mg/kg). It is crucial to ensure that every medication administered is within the recommended safe dosage range. The following are the most common situations in which this precaution will be required: Medications used with infants and children Medications used in critical care
Powders
Drugs that tend to be unstable when stored in liquid form are packaged as powders that need to be reconstituted prior to administration. Once the medication is reconstituted, the solution will be useable for a specific period of time as recommended by the manufacturer. The timeframe for use of reconstituted powders is usually 1 to 14 days. Therefore once a powder is reconstituted it will need to be refrigerated. The manufacturer will include directions for the type of diluent to be used for reconstitution. The most common diluents are sterile water, normal saline, 5% dextrose and water, or bacteriostatic water. The manufacturer will identify the amount of diluent to be added to the powder to equal a concentration of the medication after reconstitution. An example of this would be directions to add 3 mL of normal saline to a vial of medication to equal 50 mg of medication in each 1 mL of solution. It is imperative that the manufacturer's directions be followed exactly to ensure accuracy and patient safety.
Injectable Preparations introduction
Drugs to be given by the injectable route are those medications that are given outside the gastrointestinal tract. The injectable route is used when the patient cannot take the medication by mouth or when a more rapid response is desired. Medications to be given by the injectable route are supplied in liquid, powder, and prefilled syringe forms. The supplies used to prepare and administer injectable medications vary depending on the administration route. In this module injectable medications that are administered by subcutaneous, intradermal and intramuscular routes are discussed, including forms of insulins. These injectable medications are also known as a type of parenteral medication, which are medications that administered by either injection or infusion. Non-parenteral medications are medications that are administered through the gastrointestinal tract, either orally, through a gastric tube or via the rectal route.
Enteral nutrition cont'd
Enteral feedings may be given through: A nasogastric tube (NG), which is inserted through the nose. These are generally used for more short-term therapy. A gastrostomy tube, which is inserted surgically into the stomach for long term use. A jejunostomy, which is inserted surgically lower in the gastrointestinal tract, the jejunum, and is also used for long term use. The methods of administration of enteral feedings are: Bolus feeding (intermittent), which is approximately 240 mL or less given at one time. It is followed by a rinse with a minimum of 30 to 60 mL of water. Feedings with this method are given several times per day for the patient to receive an adequate amount of calories and hydration. Continuous feeding, which is given by gravity flow from a bag regulated with a roller clamp or by an infusion pump made for enteral feedings. Full Strength or Diluted? Commercially prepared formulas are formulated to be given at full strength, but they are not tolerated by all patients. If the patient develops vomiting, cramping, or excessive diarrhea, then the formula may be diluted with water based on consultation and changes in the orders by the health care provider (HCP).
Intermittent Intravenous Administration
Frequently, the nurse will give medications via the intermittent IV route. There are many advantages to using this route, including the following: Rapid therapeutic concentration of the drug Control over the onset of action and peak concentrations Ability to achieve blood concentration levels when the medications cannot be taken by the oral route
meanings of the variables in calculations
H: the dosage on hand or in the container V: the vehicle or the form in which the drug comes (tablet, capsule, liquid) D: the desired dosage (which is the amount of medication ordered) X: the unknown amount to give
Ratio and Proportion
H:V::D:X
Heparin IV infusion
Heparin is a potent anticoagulant that acts to interfere with blood coagulation and blood clot formation. The dose of heparin to be administered is ordered according to the patient's weight. The effectiveness of heparin is monitored with periodic measurements of the partial thromboplastin time (PTT) or the activated partial prothrombin time (APPT). The PTT and APPT are laboratory measurements of the patient's intrinsic coagulation cascade. If the patient is receiving therapeutic anticoagulation, the desired ranges for PTT and APPT are between 1.5 and 2.5 times the normal values. The nurse will follow the health care provider's order, which may be in the form of a "standing order" or "standard orders" that includes a nomogram, to determine how often to have the patient's PTT or APPT measured and, on the basis of the results, how much to increase or decrease the hourly dosage of IV heparin to maintain the PTT or APPT within the therapeutic range. Recently, the antifactor Xa assay is becoming a common monitoring method to guide titration of heparin infusions. Although it is a more expensive testing method, initial research is showing that patients tend to need less dosage adjustments and therefore less testing than when an APTT or PTT are used. Target values of 0.3 to 0.7 units/mL guide the heparin infusion being titrated up or down. For an example of a standing order with a nomogram for administration of heparin by IV infusion, click IV heparin bolus and continuous infusion orders.
Example Problem: Volume to Volume—Percent Solutio
Here is an example of how to use the ratio and proportion method or the fractional equation method to calculate the volume of drug in milliliters needed to prepare a solution containing the desired percentage of medication. Example: Prepare 500 mL of a 5% solution of dextrose in water Ratio and Proportion Method Known drug : Known volume :: Desired drug : Desired volume 5 mL : 100 mL : : X mL : 500 mL 100 X = 2500 X = 25 mL Answer: 25 mL of dextrose is needed.
Example Problem: Volume to Volume—Volume Solution
Here is an example of how to use the ratio and proportion method or the fractional equation method to calculate the volume of drug in milliliters needed to prepare a solution containing the desired volume:volume ratio of medication:solvent. Example: Prepare 200 mL of a 1:5 Betadine:saline solution for a wound wash. Ratio and Proportion Method Known drug : Known volume :: Desired drug : Desired volume 1 mL : 5 mL : : X mL : 200 mL 5X = 200 X = 40 mL Answer: 40 mL of Betadine solution is needed.
Example Problem: Preparing a Weaker Solution from a Stronger Solution
Here is an example of how to use the ratio and proportion method or the fractional equation method to calculate the volume of higher-percent solution needed to prepare a weaker/lower percent solution. Example: Medication Order: Prepare 400 mL of a 4% solution. Available: 8% solution Use water as the solvent. Ratio and Proportion Method Desired % : Available % :: Desired volume : Known volume 4% : 8% : : X mL : 400 mL 8 X = 1600 X = 200 mL Answer: 200 mL is the "desired volume" of 8% solution needed to prepare the weaker solution. Next, calculate the volume of solvent to be used: Volume of solvent = Known volume - Desired volume X mL = 400 mL - 200 mL X = 200 mL To prepare 400 mL of a 4% solution, add 200 mL of 8% solution to 200 mL of water (solvent). Fractional Equation Method Answer: 200 mL is the "desired volume" of 8% solution needed to prepare the weaker solution. Next, calculate the volume of solvent to be used: Volume of solvent = Known volume - Desired volume X mL = 400 mL - 200 mL X = 200 mL To prepare 400 mL of a 4% solution, add 200 mL of 8% solution to 200 mL of water (solvent).
Labor and Delivery: Titrated Medications
How are titrated medications mixed? Titrated medications are added to a specific volume of an IV solution. The IV solution is labeled to identify the total dose of medication in the solution. The nurse then calculates the dose (usually in milligrams, micrograms, units, or milliunits) per milliliter of solution. How do you administer a titrated medication? Parameters are written in the orders to guide the nurse as to the amount of drug that should be administered on the basis of the patient's clinical finding. The nurse has some discretion on how much medication the patient is to receive and adjusts the amount on the basis of the patient's response to the medication.
Ideal Body Weight
IBW is calculated with the use of a formula in which weight is adjusted on the basis of height. This formula replaces the height/weight tables formerly used to estimate ideal weights for adults and is used for nutritional assessment: Male: 50 kg + 2.3 kg for each inch over 5 feet Female: 45.5 kg + 2.3 kg for each inch over 5 feet
Loading Doses
In some situations, an initial loading dose (a bolus at the start of the infusion) of titrated medication is administered over a short period of time before the continuous infusion of titrated medication is begun. The loading dose achieves a therapeutic serum level of medication rapidly. Loading doses are considered part of the patient's total IV fluid intake. Therefore, when a loading dose is given, the rates of administration of primary and secondary IV fluids must be adjusted to maintain the ordered rate.
volume to volume
In the previous lesson, medication solutions were expressed in weight (grams) of medication per volume (milliliters) of solution. However, the usual unit of measure for a dose of a medication in solution is volume of solution in milliliters (mL). The following is a scientific fact: At 4° C, 1 mL of water = 1 g. For the preparation of medication solutions outside the pharmacy, a dose of medication in grams can be considered to equal the dose of medication in milliliters. The concentration of a solution comprising two solutions may be ordered as a ratio (volume of solute [medication]:volume of solution) or as a percent of solute (medication) in the solution. To calculate the volume of drug in milliliters that must be used to prepare a solution ordered as a volume:volume ratio or as a percentage, use the ratio and proportion method or the fractional equation method. The equations are as follows: Ratio and Proportion Method Known drug : Known volume :: Desired drug : Desired volume
Administration of IV Medications (Milliliters per Hour)
In the previous problems, you calculated the concentration of medication in solution and then calculated the volume of secondary IV solution to be infused. This is the preferred method in labor and delivery. However, there may be times when the health care provider will order the IV medication to be administered as a certain volume (in milliliters) per hour. In other words, the order will tell you how many milliliters of the IV medication solution to administer per hour.
Unit-Dose Dispensing System (UDDS)
In the unit-dose dispensing system, the pharmacy provides the individual doses for the patient in packets or containers. These doses are stored and delivered to each patient area. Unit dose carts/cabinets are commonly used to store these medications. The unit dose cart/cabinet is filled by the pharmacy with 24 hours of medication, and each drawer may be refilled or exchanged every 24 hours. Before administering a medication, the nurse must access the drawer and withdraw the appropriate patient medication. The labels on the individualized drawers of the unit dose cart/cabinet generally contain the following: The patient's name The patient's room number The patient's bed number
Several reasons why a pregnant patient might receive IV fluids:
Inability to tolerate food and fluids in early pregnancy To slow or eliminate uterine contractions in preterm labor Before the induction of anesthesia To provide fluid and electrolytes during labor To induce or augment of labor To provide ready access for IV medications that may be needed
Insulin IV infusion
Insulin is a potent medication that is used to help maintain blood glucose (BG) levels in the body. The effectiveness of a dose of insulin being administered by IV infusion is monitored with the use of blood glucose measurements. These measurements can be conducted with a glucometer at the bedside or performed on a blood sample in the laboratory. A blood glucose measurement is performed by the laboratory at least once every 24 hours. The nurse will follow the health care provider's order or "standard standing orders," to determine how often to measure blood glucose levels and, on the basis of the level, how much the dosage (IV infusion rate) of insulin should be increased or decreased to maintain a therapeutic level. Regular humulin insulin is generally mixed in normal saline or D5W for the infusion. Insulin is compatible with most medications and blood products.
Sites and angles for insulin injections
Insulin is a protein that can only be given by injection. The gastrointestinal (GI) secretions destroy the insulin structure. Persons injecting their own insulin usually use sites #3, 4, 5 and 6. Those who administer insulin to others usually use sites #1 and 2 (upper arm or the deltoid area). The absorption rate of insulin from sites #3, 4, 5 and 6 is slower because there are fewer blood vessels in the fatty tissue than in the muscular tissue. Sites for Insulin Injection arm, stomach, thighs For most people, insulin is administered at a 45-degree angle into the subcutaneous tissue. If a person is obese, the angle may increase to 90 degrees.
insulin, clear or cloudy?
Insulin is either clear or cloudy. Rapid-acting insulins (aspart, glulisine, lispro and regular) are clear, and they are the only insulins that can be given intravenously. Most other forms of insulin have a uniform cloudiness after being gently rolled between your hands to mix them. Two new long-acting insulins, Lantus and Levemir are clear, but they cannot be mixed with any other insulins.
Insulin Bottles
Insulin is prescribed and measured according the US Pharmacopeia (USP) units. Most insulins are produced in concentrations of 100 units/mL. Insulin should be administered with an insulin syringe that is calibrated to correspond with the 100 units of insulin bottle. DO NOT use a tuberculin syringe. The insulin bottle should state that it is 100 units/mL and the syringe should be a U100 (100 units/mL) syringe.
Angles for injection
Intradermal- 10 to 15 degree angle Subcutaneous- 45 to 90 degree angle Intramuscular- 90 degree angle
IV access sites
Intravenous access sites are necessary when patients cannot take fluids or medications through the oral route. Vascular access is necessary for the delivery of IV drugs and fluid. The length of time the IV is needed often determines the site and type of IV used. Central Venous Catheter (CVC): The sites for the CVC are the superior vena cava and the inferior vena cava. The insertion of this IV requires a minor surgical procedure, and the length of the catheter ranges from 6 to 28 inches. This type of IV is used for patients who require long-term medications, nutritional support, or IV fluids. PICC (Peripherally Inserted Central Catheter): This IV is used for long term therapy for up to 1 year. The length of the catheter is generally from 25 to 60 cm. Some catheters can be trimmed to the desired length, others are inserted to the needed depth with the remaining excess left outside. Even though this catheter is inserted through a peripheral vein, it extends to the superior vena cava and is considered a central line. Vascular Access Ports: This type of catheter is for long-term use and has an implantable infusion port. The infusion port is inserted in the subcutaneous tissue.
Intravenous Route introduction
Intravenous route refers to the administration of a variety of fluids and/or medication directly into the vein. Intravenous administration is used to replace fluids and electrolytes, provide nutrition, and provide access for medications. Medications given by this route are absorbed directly and act rapidly. Medications that cannot be given orally because they cannot be absorbed in the gastrointestinal tract often can be given intravenously. The preparation of medications for intravenous administration and the proper method of administration are important nursing functions.
Critical factors of IV for mom and baby
It is of critical importance to remember that the nurse caring for a pregnant woman has two patients: The mother The baby The following factors are also critical to keep in mind: Any medication given to a pregnant woman may affect her baby. Medical conditions that impair renal function require close monitoring. Medications that influence urinary output require close monitoring. Detailed assessment is required. The primary means of assessing the unborn child is monitoring the fetal heart rate
IV Fluid Calculations: Electronic Infusion Devices
Many of the medications that are administered by IV in the labor and delivery areas are administered using an electronic infusion device. There are several different types of electronic infusion devices. However, the basic principle on which these devices operate is the same: the device exerts pressure on the fluid so that the fluid is pushed through the IV tubing at a specific flow rate per hour that is set by the nurse. To calculate the infusion or flow rate for fluid delivered by an electronic infusion device, the nurse calculates the rate in milliliters (mL) per hour, with the use of the following formula: ON FORMULA SHEET
Mix-O-Vials
Medications that are packaged in Mix-O-Vials have the powder form of the medication in the bottom compartment and the diluent solution in the top portion of the vial. The powder and the liquid are separated by a rubber stopper. Medications that are unstable in solution over long periods of time are packaged in this manner.
Ampules
Medications that are packaged in ampules are intended for one-time use. The ampule is designed to break at the neck of the ampule. The neck may have a prescored line or marked ring around the neck to indicate where the ampule neck should be broken. The neck of the glass ampule is broken and the medication removed with a syringe and needle.
Vials
Medications that are packaged in vials are available in a variety of sizes. There are vials that are intended as single-dose vials and those that are multi-dose vials. The vial can be plastic or glass and has a rubber diaphragm over the top. The vial is a closed system and therefore requires that air be injected to equal the amount of solution to be withdrawn.
Introduction to Calculating the Amount of Drug or Concentration of a Solution
Most critical care medications are intravenous medications, which are expressed as units per milliliter (units/mL), milligrams per milliliter (mg/mL), or micrograms per milliliter (mcg/mL). The first step in preparing to administer a critical care medication is to determine the concentration (dose) of medication per milliliter of solution (concentration). All IV medications (except those administered via direct IV push) are administered with an infusion pump in the critical care unit. Infusion pumps are now "smart pumps" in that the drug is selected from the drug library, the concentration per milliliter is selected, the patient weight and dosage order are entered and the pump then calculates the correct dosage in mL/hour. The nurse must verify that the correct drug, concentration, weight, and drug dosage have been entered and that the calculation is accurate. Most hospitals require two nurses to verify these steps and verify calculation accuracy prior to starting the infusion.
Hydration Management
Most intravenous therapies that are available in acute care oncology units or renal units can be safely administered in a patient's home. The criteria for safe administration of an intravenous therapy in the home include: Patent venous access Safe home environment Responsible caregiver Order for intravenous therapy with a medication that is safe to administer in the home Most intravenous therapy medications administered in the home are prepared by the pharmacy. They are distributed and their administration monitored by nurses employed by home care agencies. As more innovative methods are developed to deliver intravenous medications safely in the outpatient setting, in-home intravenous therapy can and will be used more often. All patients should be assessed for hydration needs. Age, general physical condition, fever, fluid intake, and diagnosis must be factored into your assessment. When a patient is febrile, the need for fluids increases by 6% for each degree over the normal temperature of 98.6° F
Example Problem: Finding the Concentration of the Solution
One of the titrated medications used most often in labor and delivery is oxytocin. The following example shows a typical order for oxytocin and how to complete Step 1, finding the concentration of the solution. Example: Mix 10 units of oxytocin in 1000 mL NS. Start infusion at 4 milliunits/min. Increase by 1 to 2 milliunits/min every 15 minutes until uterine contractions are 2 to 3 minutes apart. Do not exceed 40 milliunits/min. Adjust primary IV of D5W to deliver a total volume of 100 mL of fluid per hour. Note: Calculations in this module, as in your textbook, use only the ratio and proportion method. Refer to Module 6: Methods of Calculation to review alternate calculation methods. In this example, you know that there are 10 units of oxytocin in 1000 mL of NS. To find the concentration of the solution (number of units/milliunits in 1 milliliter): First, set up your ratio and proportion formula: 10 units : 1000 mL : : X units : 1 mL Next, solve for "X": 1000 X = 10 X = 0.01 units/mL = 10 milliunits/mL The concentration of the solution is 10 milliunits/mL.
Pediatrics: Factors Influencing Intravenous Administration
Pediatric departments are establishing protocols for safe and consistent administration of intravenous fluids to the pediatric patient. Factors that can have a negative influence on the accuracy of intravenous medication administration include: the types of intravenous tubing, the length of the tubing, and the manner of filling the intravenous tubing. A pediatric patient's overall fluid intake, including intravenous fluids, must be taken into consideration. Pediatric patients are sensitive to fluid overload even when general health is not compromised. The physiologically compromised pediatric patient is extra-sensitive to excess fluid. When setting up the infusion for a pediatric patient: Infusion pump Use the minimal amount of extra fluid needed to deliver the correct dose of medication. The less extra fluid, the safer it is for the patient. Use an infusion pump or infusion control set such as a Buretrol, Volutrol, or Soluset. Using these devices is safer than using standard intravenous set-ups.
Dosage per kilogram of bodyweight
Pediatric medications are often ordered according to the child's weight in kilograms. The first step is to determine the child's weight in kilograms. The second step is to determine the amount to be given on the basis of the child's weight in kilograms. Let's look at the two steps: Step 1 Calculate the patient weight in kilograms. (Remember that 2.2 pounds = 1 kilogram.) Step 2 Multiply the number of kilograms by the dosage ordered per kilogram.
percents
Percents are the concentrations of weight dissolved in a volume and are expressed as units of mass per units of volume. These concentrations are expressed as percentages. The percentages are based on the definition of a 1% solution as 1 g of a drug in 100 ml of solution. For example, dextrose 50% in a 50-ml prefilled syringe is a concentration of 50 g of dextrose in 100 ml of water. Proportions can also express concentrations. A solution that is 1:100 has the same concentration as a 1% solution.
Prefilled syringes
Prefilled syringes are intended for a single dose. The prefilled syringe may come with or without a needle and/or plunger. You may need a Tubex or Carpuject closed injection system. The syringe will be marked with the amount of medication within the volume in the syringe. Once the calculation of the correct dosage is completed, any excess medication can be disposed of and the syringe is ready for use. The prefilled syringes may come complete with a needle and a plunger; however, if it does not, a Tubex or Carpuject may be needed. Many institutions do not allow the use of Tubex or Carpuject holders any longer as they pose a risk for infection. They are used on multiple patients, going from room to room without disinfection in between. Most facilities now require single use disposable syringes for all injections. Be sure to follow your facility policy.
Primary and Secondary IV Fluids
Primary IV fluid The maintenance fluid used when an IV medication is also given. This is usually ordered as a specified amount to be delivered continuously per hour. Secondary IV fluid The IV medication is "piggy-backed" to a primary IV fluid. The volume should be included in the hourly or 24-hour total intake.
Humilin ____ is always drawn up first
R
Community Introduction
Solutions may need to be diluted in the home but the ordered dose is usually given in the metric system of measurement. The dilution in the home must usually be performed with the use of the household system of measurement. For example, quantities of solutions ordered in milliliters must be converted to quantities in teaspoons, tablespoons, or cups. When converting from metric to household measurements, always use calibrated household measuring devices for greatest accuracy. For example, measuring spoons and measuring cups will provide much more accurate dosing than eating spoons and drinking cups. All directions given to the patient or the family for preparation of the solution should be detailed and written without the use of medical terms. Include in the instructions: To use only utensils that have been cleaned by boiling or soaking in a cleaning solution; To use glass or plastic utensils rather than metal utensils, when possible; and Whether the solution should be stored in the refrigerator or at room temperature
conversion factors
Some conversion factors are used so often in the preparation of medications in the home that they must be immediately available and therefore should be memorized. Click the image to the right to view a table of conversions from household to metric measurements. zoom It will be helpful to have these conversion factors memorized: Volume conversion factors: Ounces to milliliters: multiply the ounces x 29.57 Milliliters to ounces: multiply the milliliters x 0.034 Weight conversion factors: Ounces to grams: multiply the ounces x 28.35 Grams to ounces: multiply the grams x 0.035 It may be helpful to prepare a card listing all of the conversion factors described in Module 2: Conversions within Metric, Apothecary, and Household Systems. Use the card to perform the calculations in the following practice problems, and carry the card with you so that you can accurately and readily calculate doses in the patient's home.
Pediatric BSA
Some medications are ordered on the basis of the patient's body surface area (BSA) rather than the patient's weight. Body surface area (BSA) is an estimated mathematical function of height and weight. There are two methods of calculating the BSA: Square root method (more common and more accurate) Nomogram method (rarely used) Although not commonly used, BSA is the most accurate way to calculate drug dosages because the correct dosage is more proportional to the surface area of the body. BSA is commonly used in chemotherapy and in some drug dosages for infants and children. Hospital pharmacies commonly use sophisticated computer programs for calculating BSA (using the square root method) and then prepare the medication dose before sending it to the nursing unit for administration. This has become commonplace because of the extremely toxic nature of chemotherapeutic drugs and the grave outcome that could be caused by a miscalculation.
administration of oral medication
The administration of oral medications to pediatric patients requires the use of special measuring devices because most of these medications are provided in liquid form. These measuring devices include: Calibrated plastic cups Calibrated droppers Measuring spoons Oral syringes Specially designed pediatric medication dispensers The type of device used depends on the age and developmental level of the child. See which device works best for each age group. To reduce the risk of aspiration, avoid giving any oral medication when the patient is crying. Enteric-coated pills or time-release capsules must be swallowed without being chewed. Chewable tablets and capsules must be chewed thoroughly and followed with water.
Calculating the Flow Rate Using the Drop Factor
The formula for calculating the flow rate of an IV fluid using the drop factor (gtt/mL) is as follows: SCREENSHOTTED To follow is an example of how to use this formula to calculate the flow rate: Example: Infuse 1000 mL D5W every 8 hours. Drop factor: 15 gtt/mL.
dangers of BSA
The hospital pharmacy generally uses a sophisticated computer program for calculating BSA (using the square root method). This is done in the pharmacy because most of the medications calculated using BSA are extremely toxic in nature, such as chemotherapy agents. The need for increased accuracy in the dosage calculation is required because these medications have a very narrow therapeutic index. This means that the difference between giving enough medication to be effective and too much medication (which causes toxic effects) is very small; therefore accuracy in calculation is essential. Once the calculations are completed, the pharmacist generally prepares the medication dose prior to sending it to the nursing unit for administration. Many of the chemotherapy drugs are known to have toxic side effects to those mixing and preparing them via drop particulate that either come in contact with the skin or mucus membranes or are inhaled through the respiratory tract. These drugs are generally mixed under a special laminar flow, vented hood (only available in the pharmacy) with the preparer wearing special protective gear to eliminate exposure. Specially designed gloves, aprons, and respirators are used and all protective gear, medication vials, syringes, tubing and supplies are disposed of in specialized biohazardous waste specifically for chemotherapeutic agents.
Direct Intravenous Injections
The intravenous site can be used to directly instill medications when it is preferred for the patient. The direct intravenous injection is often referred to as IV push. Direct intravenous injections are more commonly used in the clinical setting because of the following advantages: IV push medications cause less discomfort. There is less tissue damage when administered correctly. IV push medications have a rapid onset of action. When administering medications by the direct intravenous route, the nurse must observe and diligently adhere to the following rules: Read drug information carefully. Know the amount of drug that can be given per minute. Know the compatibility of the drug with the IV solution. Accurately flush the tubing before and after administration of the drug. The medications given by the direct IV route are calculated in the same manner as that of medications for intramuscular (IM) injection
Intravenous Medication
The nurse administering intravenous fluids to a pediatric patient must take the patient's body weight into consideration. The table (on this screen) shows guidelines for the volume of intravenous fluid that can safely be administered over 24 hours, on the basis of the patient's weight. To better understand the guidelines, click to expand the thumbnail image. All fluids given intravenously must be included in the calculation of the pediatric patient's total 24-hour fluid intake. When intravenous lines are flushed after the administration of a medication, the amount of the flush solution is also included in the total 24-hour fluid intake. Volumetric infusion pumps, syringe pumps, and Buretrol calibrated cylinders are generally used to carefully control the amount of fluids given intravenously to pediatric patients.
Calculating Accuracy of Dilution Parameters
The nurse calculates doses of intravenous fluids per kilogram per minute for pediatric patients, just as for adult patients. However, it is important to note that for pediatric doses, the overall concentration of medication per milliliter is increased. Increasing the concentration of the titrated medication allows for delivery of the pediatric dose in a smaller amount of intravenous fluid, thus decreasing the likelihood of fluid overload. The health care provider will order the dilution as well as the medication infusion rate. However, the nurse must check the accuracy of the intravenous medication dilution order. When a change is ordered in the dosage of a pediatric intravenous medication, the nurse must recalculate the dosage using a new concentration of the solution to be sure that the new order does not change the intravenous fluid infusion rate (volume of intravenous fluid infused over time)
Nurse and insulin
The nurse has the responsibility of knowing the onset of action, the peak time of action, and the duration of the dosage. The action, peak, and duration vary with each type of insulin.
Determining whether a specific dose is safe
The nurse should verify that a specific medication dosage that has been ordered falls within the medication manufacturer's safety parameters. To determine this, three steps are necessary. The first two steps you just learned. Step 1 Calculate the patient's weight in kilograms. Step 2 Multiply the number of kilograms by the dosage ordered per kilogram. Step 3 Check the medication package insert (prepared by the drug manufacturer and included in the medication package) or your hospital's formulary for the safe dose range for that drug. Now, go back to Step 2 and multiply the patient's weight by the minimum daily dose and then by the maximum daily dose. If the dose ordered falls between the minimum and maximum daily doses, then the dose ordered is considered to be within the safe dosage range.
Preparing a solution of a desired concentration
The order for preparation of a solution of a certain concentration may be written in one of three ways, as follows: Weight-to-Weight The preparation of a solution ordered weight-to-weight involves mixing the ordered weight of a solute with the ordered weight of a solution. Example: 4 g salt in 150 g of NS This type of order can be filled in the pharmacy setting, where scales are available to accurately determine the weights of the solute and the solution. A solution ordered in this way cannot usually be prepared accurately in the home setting. Weight-to-Volume The preparation of a solution ordered weight-to-volume involves mixing the ordered weight of a solute with the ordered volume of a solution. Example: 4 g sugar in 1 L of H2O The preparation of a solution ordered weight-to-volume also requires the use of a scale. Usually, a solution ordered weight-to-volume can only be prepared in the home setting if the medication is pre-packaged by weight. Volume-to-Volume The preparation of a solution ordered volume-to-volume involves mixing a given volume of one solution with a given volume of another solution. Example: 3 T hydrogen peroxide 3% in ¾ c H2O Solutions ordered for administration to patients in the home are most often ordered as volume-to-volume dilutions.
Infusion Rate for Concentration and Volume per Unit of Time
The physician's order for administration of a titrated medication will identify whether the solution is to be infused by: Total dose per hour (Example: Infuse heparin at 5000 units/hour) or Total dose per minute (Example: Infuse terbutaline at 10 micrograms/minute) The next two sections of this module discuss how to calculate the total dose per hour and then, how to calculate the total dose per minute. In each section you will learn how to calculate the medication dosage ordered using the four methods described in previous modules and will then be presented with some practice problems.
Measuring correct doses with a syringe
The plunger of the syringe has a rubber head that has a raised section at the tip, a flat middle ring that touches the sides of the barrel, and the bottom end of the head that attaches to the remainder of the plunger. The measurement of the correct dosage is determined by the rubber end of the plunger that is closer to the tip of the syringe.
Continuous Intravenous Adminstration
The primary health care provider will order the amount of solution to be given over a specific time. Infusions may be given via an infusion pump or it may be given by gravity controlling its rate by manipulating a roller clamp. If given by gravity drip, it will be the responsibility of the nurse to calculate the IV flow rate according to the drop factor, the amount of fluids to be administered, and the infusion time. Once the flow rate is determined (gtt/min), the nurse must regulate the delivery of medication by manipulating the drop in the "drip chamber." This is done by the nurse counting the number of drops over a 1-minute period until it is set at the appropriate rate. As discussed, there are two basic types of drip chambers: macrodrip and microdrip. Each looks slightly different, and the rate of delivery is different. Let's look at an example: If the order was to deliver an IV solution at 100 mL/hour, either a macrodrip (drop factor = 15 gtt/mL) or microdrip (drop factor = 60 gtt/mL) could be used. You would calculate the delivery rate and determine the following: Macrodrip = 25 gtt/min of IV solution Microdrip = 100 gtt/min of IV solution
Parenteral medications
The supplies used to administer parenteral medications include syringes and needles of various sizes. Parenteral medications are prepared in two forms: liquid and powder. An understanding of these supplies and forms will assist you in understanding the administration of parenteral medications.
Expressing the strength of a solution
There are three ways to express the strength of a solution, as follows: Ratio The strength of a solution may be expressed as a ratio. Example: A solution of 1:20 acetic acid in water This solution consists of 1 part of acetic acid (the solute) in every 20 parts of solution, with water as the solvent. Fraction When the strength of a solution is expressed as a fraction, the solute (medication) is in the numerator and the total volume of the solution is in the denominator. Example: 5 g/100 mL acetic acid in water This solution consists of 5 g of acetic acid in a volume of solution totaling 100 mL with water as the solvent. Percentage The strength of a solution may be expressed as the percentage of solute (the medication). Example: 5% acetic acid in water This solution consists of 5 parts of acetic acid in every 100 parts of solution with water as the solvent.
Mixing Medications
There are times when the nurse needs to mix two medications in a single syringe. The main reason for this procedure is patient comfort. When two medications are to be given by intramuscular injection and they are capable of being mixed, the patient is subjected to one injection as opposed to two. There are two main precautions to be taken when deciding whether to mix the medications. First and foremost, the two medications MUST be compatible with each other. Being compatible means that the two drugs do not: act to negate the action of either one or both of the medications, or create precipitates when mixed. Secondly, the total volume when the medications are mixed is 3 mL or less. There are three methods of mixing medications. Read pages 163 to 166 in your textbook. Suppose you need to draw up 1/2 mL of one medication and 1 mL of another. How would you do this? The way the medication is delivered will determine what method you use. Click on the METHOD buttons to view each of the methods of mixing two medications.
Insulin pen devices
There are two types of insulin pen devices: pre-filled and reusable. Both types require insulin pen needles to dispense the insulin. Pre-filled insulin pen devices are filled with 300 units or 3 mL of 100 unit/mL of insulin. Before each insulin dose, a small disposable needle is placed on the end of the insulin pen device and the insulin dose is dialed in. After the dose is dialed, the needle is placed subcutaneously and the plunger pushed down. After the insulin is delivered, the dose indicator returns to zero and the needle is removed from the skin. The prefilled pen device is reused for multiple injections until all the insulin is dispensed. Reusable insulin pen devices are filled with disposable insulin cartridges. The cartridges are filled with 150 units (1.5 mL) or 300 units (3 mL) of U-100 insulin. The cartridge is placed on the pen device. Before each insulin dose, a small disposable needle is placed on the end of the insulin pen device and then the insulin dose is dialed in, the needle is placed subcutaneously, and the plunger is pushed down. Following the insulin delivery the dose indicator returns to zero and the needle is removed from the skin. The device is used for multiple injections until all the insulin is dispensed from the cartridge.
Example Problem: Hydration Management
There is a standard formula for daily fluid intake: 100 mL/kg for the first 10 kg of weight 50 mL/kg for the next 10 kg of weight 15 mL/kg for the remaining kg Example: Adult weighs 85 kg 10 kg X 100 mL/kg = 1000 mL 10 kg X 50 mL/kg = 500 mL 15 mL/kg X 65 kg = 975 mL Total fluid needs = 2475 mL This standard formula includes fluid that is contained in foods. To determine how much liquid alone an adult needs to consume, multiply the daily fluid intake by 75%. Therefore, an 85-kg adult who is able to consume food and fluids would have a daily fluid intake need of: 2475 mL X 75% = 2475 mL x 0.75 = 1856.25 or 1856 mL of fluid/day As noted earlier, patients with a fever will need an increase in their fluid intake by 6% for each degree over normal body temperature (98.6° F). If the 85 kg patient had a temperature of 100.6°, he would need a 12% increase in fluids or: 1856 mL X 12% = 1856 X 0.12 = 222.72 mL or 223 mL additional fluids 1856 mL + 223 mL = 2079 mL fluid/day
Combination insulins
These are also a combination of rapid- and intermediate-acting insulins
Example Problems: Calculating Primary and Secondary Rates
Titrated IV medications ordered for a pregnant patient are infused as secondary IV fluids. To carry out an order for a titrated IV medication, the nurse first starts the primary IV infusion and then starts the secondary (titrated) IV solution at the prescribed infusion rate, concurrently decreasing the flow rate of the primary IV solution to maintain the total number of milliliters per hour at the prescribed rate. When the IV medication order includes a loading dose of the titrated medication, the calculations include a total of six steps. Click on the links below to view animations of the steps to calculate the infusion rates of the primary and secondary IV infusions for a titrated IV medication with a loading dose. First, calculate the primary IV infusion rate in drops per minute. Next, calculate the secondary IV infusion rates: Step 1: Calculate the volume of medication needed to make the titrated solution Step 2: Calculate the concentration of the titrated solution Step 3: Calculate the volume of the titrated solution needed to supply the loading dose Step 4: Calculate the secondary infusion rate per hour (for electronic infusion devices) Step 5: Calculate the secondary (medication) infusion maintenance rate Finally, decrease the primary infusion rate appropriately to adjust for administration of the loading dose and the secondary infusion rate.
IV Fluid Flow Rate (Milliliters per Hour)
Titrated IV medications specify maintenance of a total flow rate of IV fluids (total milliliters per hour). The total infusion rate is maintained by subtracting the flow rate of the secondary IV infusion from the total infusion rate to determine the rate of the primary IV infusion. Each time the medication dose rate is titrated up or down, the flow rate of the primary infusion must be changed in the opposite direction (decreased or increased) the same amount to maintain a total (primary plus secondary) flow rate. In the examples just provided, the total flow rate was 100 mL/hr. The titrated medication (secondary IV) was to be started at 24 mL/hr. The primary IV must be started at 76 mL/hr to maintain the total hourly flow rate of 100 mL/hr.
Titration
Titration refers to the actual adjustments (increase, decrease, or no change) the nurse makes to the infusion rate on the electronic infusion pump to increase, decrease, or maintain the rate of infusion of the medication within a set of parameters to achieve the desired response in the patient. A general principle of medication administration for titrated medications is that an electronic infusion pump is always used. A morphine drip may be titrated up or down in response to a patient's level of pain. An insulin drip may be titrated up or down in response to a patient's hourly blood sugar levels. A lidocaine drip may be titrated up or down in response to an increase or decrease of irregular heartbeats.
Calculations for Titrated Medications
To administer a titrated medication, the nurse must calculate the titration factor, which is the number of milliliters per hour (for an electronic infusion device) by which the IV infusion (flow) rate must be changed to deliver the ordered change in dose of the titrated medication. The following three steps are used to calculate the titration factor: Find the concentration of the titrated medication (secondary IV) solution; this may be expressed as units per milliliter (units/mL), milligrams per milliliter (mg/mL), micrograms per milliliter (mcg/mL), or milliunits per milliliter (milliunits/mL). Note: One unit equals 1000 milliunits. Calculate the initial infusion rate in milliliters per hour. Calculate the titration factor (dose per minute = dose per hour). The following screens will guide you through each of these steps in order, with an opportunity to practice each step before moving on to the next. It is important that you proceed through each step and complete the practice problems before going to the next step.
Calculating Primary and Secondary IV Fluid Rates
To calculate primary (maintenance) and secondary (medication) IV fluid rates: Calculate the drop rate per minute or If an electronic infusion device is used, calculate the milliliters per hour
tip
To obtain the "Desired volume" of a volume:volume solution, use the following formula to calculate how much solvent to use: Desired volume - Desired drug = Solvent 200 mL - 40 mL=160 mL
transdermal medication: topical creams and ointments
Transdermal medications also include some topical creams and ointments, such as nitroglycerin. These transdermal medications are applied by the inch. Nitroglycerin ointment or cream is applied by the inch, as prescribed by the health care provider, to a small sheet of paper and the paper is placed on the skin. The paper used to measure nitroglycerin ointment or cream is supplied with the medication. Transdermal ointment or cream medications are ordered by medication name, medication formulation and strength, the amount to apply, and the number of times the medication is to be used in a 24-hour period.
Loading Doses in the Pregnant Patient
What type of medication would you be administering when giving a loading dose with a labor-and-delivery patient? Magnesium sulfate is one of the most common IV medications that is administered as a loading dose followed by a continuous infusion. Magnesium sulfate is supplied in syringes or vials that contain a certain volume of a certain percent solution—for example, a syringe with 50 mL of a 50% solution or a vial with 10 mL of a 50% solution. How is the IV loading dose prepared and given? The first step is to prepare the titrated solution containing the ordered number of grams of medication per milliliter of solution. From this solution a loading dose followed by a continuous infusion may be administered.
Weight to Volume
When the concentration of a known medication solution is expressed as a ratio of weight in grams to volume in milliliters, it is possible to calculate: The desired dose expressed as a fraction (weight in grams per volume in milliliters) of the available solution The desired dose expressed as percentage of the available solution The desired grams of medication in a desired volume of solution or the percentage of medication in solution can be calculated using one of two methods, the fractional equation method or the ratio and proportion method. The equations for these methods are as follows: Ratio and proportion method- Known drug:Known volume::Desired drug:Desired volume
Tuberculin syringe
a 1-mL slender syringe that is calibrated in tenths (0.1 mL), hundredths (0.01 mL) and minims. -this syringe is used when the amount of drug solution to be administered is less than 1 mL and for pediatric and heparin dosages. -also available in a 1/2 milliliter (mL) syringe
Computer-based drug administration (CBDA)
a technical software system created to prevent medication errors This technical software system is composed of the following systems: Computerized Prescriber Order System (CPOS) Bar Code Medication Administration System (BCMA) Electronic Medication Administration Record (eMAR) Pharmacy Information System (PIS)
oral medications
absorbed by the gastrointestinal tract, particularly the small intestine, These medications are referred to as being administered "PO" (per os or by mouth)
Subcutaneous Injections
absorbed slowly because there are fewer blood vessels in the fatty tissue -amount of drug administered subcutaneously is generally 0.5 to 1 mL at a 45, 60, or 90 degree angle -tuberculin and insulin are the two types of syringes used for subcutaneous injection
Pediatric IM injection
administration site: The appropriate site for the administration of an intramuscular injection is dependent on the age and muscular development of the patient. Review the injection sites appropriate for each age group, from birth to adolescence needle size: Usual needle length for infants and children is ½ to 1 inch. A method of estimating the needle length needed is to grasp the muscle for injection between the thumb and the forefinger; half the distance would be the desired needle length patient preparation and support: The least amount of restraint that can be used should be employed. The younger the child, the more preparation is directed toward the parents in order to have them provide assistance. Older children should be given honest explanations as to what to expect. All children should be provided reassurance and comfort immediately following the injection, regardless of their behavior.
the most common types of eye drops and eye ointments are:
antibiotics anti-glaucoma medications hypoallergenics pupil dialators operative medications moisturizers
common types of vaginally inserted medication:
antibiotics anti-inflammatories
Most common types of suppositories:
antiemetics stool softeners laxatives gastrointestinal inactivated meds
most common types of pharyngeal sprays, mouthwashes, and lozenges
antiseptics analgesics
pharyngeal spray, mouthwash, and lozenges
applied to mouth and throat. intended to relieve pain and discomfort in the mouth and throat.
Capsules
are a form of medication that are hard or soft gelatin shells that contain powder, liquid, or oil, or time pellets. They come in a variety of colors, shapes, and doses. -Capsules that come as timed release, sustained release, and controlled release work over a period of time and should always remain intact when being administered.
PRN orders
are given at the patient's request and at the nurse's discretion concerning safety and need. Narcotics are time-framed and renewed every 48-72 hours. ex) acetaminophen for fevers ondansetron for nausea
Suspensions
are liquid forms that contain solid particles in liquid, which must be mixed prior to preparation -All suspensions must be thoroughly mixed immediately before administration.
Elixirs
are liquid preparations usually used with drugs that do not dissolve in water and are a mixture of alcohol and water
Tablets
are prepared from powdered drugs that have been molded into different shapes and sizes. they come in a variety of colors, shapes, and doses. many tablets are scored so that they can be broken down into halves or quarters- meaning they are marked with indentations that allow that allow the nurse to break the tablet in halves or quarters. some tablets may be "enteric coated" -Only tablets that are scored should be used for half or quarter doses. Enteric coated tablets should not be crushed because the enteric coating provides a hard shell for the capsule to ensure that the capsule is not dissolved in the stomach but rather is dissolved in the intestine.
sublingual tablets
are readily absorbed by capillaries under the tongue
Five-milliliter syringe
calibrated in 0.2 mL increments -usually used when the fluid needed is more than 2 1/2 mL -this syringe is frequently used to draw up appropriate solution to dilute the dry form of a drug in a bill because the volume needed for reconstitution is generally more than 2 1/2 mL.
Three-milliliter syringe
calibrated in tenths (0.1 mL).
a drug that has its strength measured by weight uses a _______________ assay
chemical
the strength of a medication is based on either a _____________________ assay or a biological assay
chemical
Needles
consists of a: -hub (large metal or plastic part attached to the tip of the syringe) -shaft (thin needle length) -bevel (end of the needle)
when solving BSA problems, it is necessary to?
convert weight and height to the same system of measurement
Needle size
determined by gauge (diameter of the shaft) and by length.
most common types of skin medications are:
emollients analgesis
chemical assay
ex) milligrams or grains
Concentration and Volume per Hour and Minute With a Drug in units
find volume per minute mL/min find concentration per minute units/min find concentration per hour units/hr
caution with enteric coated tablets
have a special coating that allows them to move through the stomach and be dissolved in the small intestine so that the medication doesn't irritate the gastric mucosa
caution with layered tablets:
have medications that may be released at different times. the outer coating dissolves quickly, and the tablet core will dissolve slowly
eye drops and ointments
instilled medications also include drops and ointments. eye drops and ointments are instilled into the conjunctival sac.
intraspinal medication
intraspinal access devices are catheters and infusion pumps used for the delivery of narcotics, anesthetic agents, or antispasmodic mediations to relieve pain or to control severe muscle spasms. the two access areas for this medication are the epidural space and the intrathecal space of the spine. The catheter is inserted by the health care practitioner and is then secured. Medication can then be administered through the catheter via an infusion pump. Epidurals are given frequently in the labor and delivery setting and both intrathecal and epidural medications are seen with surgical procedures. Small implantable pumps can be surgically placed under the skin of the abdomen to deliver medication through an intrathecal catheter for chronic conditions. Medications such as baclofen or morphine may be delivered in this manner to minimize the side effects often associated with the higher doses used in oral or intravenous delivery of these drugs.
Titrated Medication
is a medication that is added to a specific volume of IV solution. The subsequent mixture will have a label that will identify the total dose of medication in the total volume of solution. The nurse then calculates the dose of titrated medication, most commonly expressed in milligrams (mg), micrograms (mcg), or units per milliliter of solution. To titrate (adjust) an infusion rate to maintain desired blood levels of a medication, you must consider the following factors: The concentration of medication in the solution The rate of solution infusion The concentration of medication per kilogram of patient weight The titration factor
Insulin
is a parenteral medication that is administered as treatment for diabetes mellitus type I. Patients with diabetes mellitus type I do not secrete adequate amounts of the hormone insulin from the islets of Langerhans in the pancreas. Patients with diabetes mellitus type II may also require insulin injections if they lack adequate insulin production. The lack of adequate amounts of insulin prevents the body from maintaining the proper levels of blood sugar (glucose). Various types of insulin are available to assist the patient in maintaining proper levels of blood glucose. The accuracy of dosage calculation and administration of insulin is very important. Inaccuracies in dosages or route of administration can be life-threatening.
mixed number
is a whole number and a fraction ex) 1 3/5 mixed numbers can be changed to improper fractions by multiplying the denominator by the whole number, then adding the numerator ex) 1 3/5= 8/5 (5 x 1 +3= 8/5)
Enteral Nutrition
is administered when the patient cannot take food orally. Rather than have a patient on long-term intravenous therapy, a feeding tube may be inserted. The cost of enteral feedings is much less than that of intravenous therapy and there is less risk of infection. There are various ways in which the tube can be inserted. Also, there are different uses for the tube.
STAT orders
is for a one-time dose of drug to be given immediately
standing orders
many be typed or written on the patients order sheet. it may be an order that is given for a number of days, or it may be a routine order that is part of an order set that applies to all patients who have had the same type of procedure. standing orders may include PRN orders.
Pre-filled drug cartridge and syringe
many injectable drugs are packaged in pre-filled disposable cartridges. The disposable cartridge is placed into a reusable metal or plastic holder. -a prefilled cartridge usually contains 0.1 to 0.2 mL of excess drug solution (excess solution must be expelled before administration)
eye drops: antibiotics
medications instilled to treat infection of the conductive or lacrimal glands (tear ducts)
bronchodilators
medications intended to dilate the bronchial passages
skin medications: emollients
medications intended to protect the skin, reduce irritation, and decrease dryness and itching
eye drops: hypoallergenics
medications intended to relieve allergies
skin medications: analgesics
medications intended to relieve pain
eye drops: anti-glaucoma medications
medications intended to treat glaucoma
glucocorticoids
medications that are anti-inflammatory drugs
Transdermal Patch
medications that are applied to the skin and deliver medication in a sustained-release manner over a number of days. transdermal medication is absorbed through the skin and enters the systemic circulation. ex) patch or disk, or paste cream or ointment
vasoconstrictor
medications that are intended to constrict the blood vessels in the nasal passages, thus decreasing nasal congestion
mucolytics
medications that are intended to liquify secretions
vaginal medications: anti-inflammatories
medications that are used to assist in the reduction of vaginal inflammation
vaginal medications: antibiotics
medications that are used to treat vaginal infections
suppositories: gastrointestinal inactivated medication
medications that can be destroyed by digestive enzymes
ear drops: topical anesthetics
medications used to create an anesthetic effect
ear drops: paralytics
medications used to immobilize an insect that has entered the ear canal (for removal)
ear drops: wax softeners
medications used to loosen and soften ear wax (cerumen)
vaginal suppository
medications used to treat vaginal infection or inflammation
Body Weight (BW)=
mg/kg/day -convert Ibs to kg (2.2 Ib/kg) -multiply the kg x mg/kg/day -cross out kg, mg/day is your answer
Calculating Concentration
mg/mL mcg/mL units/mL use a ratio and proportion to solve the concentration
a nano unit is one thousandth of a
micro unit
a micro unit is one thousandth of a
milli unit
larger to smaller
move the decimal place to the right (for microgram and nanogram move the decimal 3 places to the right)
when multiplying fractions:
multiply the numerators and then the denominators, reduce to lowest possible terms
Intramuscular injections
muscle has many more blood vessels than fatty tissue, so medications given IM are absorbed more rapidly than those given by subQ injection -volume of solution for an IM injection is 0.5 to 3.0 mL, with the average being 1 to 2 mL. -a volume of drug solution greater than 3 mL causes increased muscle tissue displacement and possible tissue damage. -occasionally 5 mL of certain drugs, such as magnesium sulfate may be injected into a large muscle, such as the ventrogluteal -dosages greater than 3 mL are usually divided and given at two diffeent sites -z track injection technique delivers medication intramuscularly in a method that prevents the drug from leaking back into the subcutaneous tissue. this method is ordered for medications causing irritation to the subcutaneous tissue or discoloration to the skin -when preparing the medication, a needle change is made after the drug has been drawn up into the syringe before it is injected into the patient -common sites for IM injections are deltoid, dorsogluteal, ventrogluteal, and vests lateralis muscles
intramuscular
needle gauge- 19, 20, 21, 22 needle lengths (inches)- 1, 1 1/2, 2
subcutaneous
needle gauge- 23, 25, 26 needle lengths (inches)- 3/8, 1/2, 5/8
intradermal
needle gauge- 25, 26 needle lengths (inches)- 3/8, 1/2, 5/8
improper fraction
numerator is greater than the denominator ex) 4/2, 8/5 -reduce them to whole numbers or mixed numbers ex: 4/2= 2 ex: 8/5 (5 goes into 8 one time with three left over)= 1 3/5
one-time (single) orders
one-time orders are given once, usually at a specified time. One- time orders can include STAT orders ex) preoperative orders
short term enteral feeding
orally or nasally inserted tubes -may cause nasal or pharyngeal irritation if prolonged use
for steroid inhalers:
patient should rise mouth to prevent sore throat, or fungal overgrowth and infection
sublingual medications
preparations include tablets and sprays placed under the tongue and are readily absorbed by capillaries under the tongue -Sublingual medications should not be swallowed because this will prevent them from having the desired effect. Patients should not take fluids until the sublingual medication has dissolved.
Liquid medicines
preparations of medicines are available as elixirs, suspensions, emulsions, tinctures and syrups. they may be opaque or clear-colored and they may be sweetened or flavored to mask the taste. medications that are still unpalatable may be mixed with 30 to 60 mL of fruit juice to help mask the taste
quotient
product or answer
quarts
qt
liter and __________ are interchangeable
quarts
meniscus
read the bottom part of the meniscus -When pouring medication into a medicine cup, the nurse notices that there is a concave or hollowed curvature on the surface of the solution. This is called the meniscus and is caused by the surface tension of the liquid against the wall of the container. For exact dosage measurement, read the bottom point of the meniscus.
Intradermal Injections
shallow and designed to deliver medication between the dermis and epidermis -typically used for skin testing -inner aspect of forearm is often used for diagnostic testing bc less hair and test results are easily seen -needle is inserted with the bevel upward at a 10 to 15 degree angle
caution with liquid medication that can irritate the gastric mucosa
should be diluted in at least 6 ounces of fluid, preferably 8 ounces of fluid
caution with liquid medication that can stain teeth:
should be well diluted and taken through a drinking straw
when dividing fractions:
skip, flip, multiply
caution: with time-released, sustained-release, or controlled-released talets
slowly release drug over a period of time
Two ways of calculating BSA:
square root formula or nomogram derived from the square root formula
Long-acting insulins
start working in 1 to 2 hours and last for 18 to 24 hours
Intermediate-acting insulin
start working within 1 to 2 hours and last 12 to 18 hours
Fast-acting insulin
start working within 30 minutes and last 6 to 8 hours
gastrostomy
surgically created opening in the stomach
Three main types of syringes:
the hypodermic syringe, the tuberculin syringe, and the insulin syringe. -These syringes vary in volumes of 1 mL, 3 mL, 5 mL, 10 mL, 20 mL, 30 mL, 50 mL, and 60 mL. Each syringe is designed for a specific use, but the parts of all syringes are the same.
The smaller the gauge number,
the larger the diameter of the lumen
The larger the gauge number,
the smaller the diameter of the lumen
Parts of the syringe
the tip, which is designed to hold the needle, the barrel, which is the outer portion of the syringe and is calibrated for measurement of dosages, and the plunger, which is the moveable inner portion of the syringe that when pulled back draws the medication into the syringe and when pushed forward delivers the medication to the patient.
Percutaneous medications
those that are applied to and absorbed by the skin or mucous membranes. These medications are intended to be administered at various times over a 24-hour period.
To find at what hourly rate the primary IV fluid will be delivered:
total IV fluid- secondary IV fluid
orogastric
tube inserted in the mouth
nasogastric
tube inserted through the nose
meter
unit for linear measurement or length
liter
unit for volume of capacity
gram
unit for weight
intraosseous infusions (IO)
used for the patient in an emergency situation when intravenous access is difficult or unobtainable. The IO catheter is injected directly through the bone cortex into the soft marrow interior, either manually or with a driver/drill device. Once the IO catheter is placed, the immediate access to the venous system for fluid and medication infusion.
if the first roman numeral is greater than the following roman numerals, then ADD
viii= 8 xv= 15
infusion pump is designed to measure
volume per hour mL/hr units/hr
most common types of ear drops:
wax softeners topical anesthetics antibiotics paralytics
k h d g d c m m n
weight per gram
