3Chapter 11 Topics Intravenous Preparations Equipment Used in IV PreparationPreparing IVsCalculations for the Hospital Pharmacy Technician
4Learning ObjectivesDescribe the characteristics of intravenous solutions including solubility, osmolality, and pHIdentify common vehicles for intravenous solutionsDescribe the equipment and procedures used in preparing parenteralsIdentify the components of an intravenous administration setConvert from Fahrenheit to Centigrade and vice versaCalculate the molecular weight and milliequivalents of certain substances used in the pharmacyCompute the specific gravity of liquidsCalculate intravenous rates and administration
5Intravenous Preparations The IV route of administration is usedto reach appropriate drug serum levelsto guarantee compliancefor drugs with unreliable gastrointestinal (GI) absorptionfor the patient who can have nothing by mouthfor the patient who is unconscious or uncooperative, and for rapid correction of fluid or electrolytesMost parenterals are introduced directly into the bloodstreammust be free of air bubbles or particulate matterhave many characteristics including solubility, osmolality, and pH
6Characteristics of IV Preparations Intravenous (IV) preparations are either:solutions (in which ingredients are dissolved)suspensions (in which ingredients are suspended)Most parenteral preparations are made of ingredients in a sterile water mediumSome parenteral preparations may be oleaginous (oily)
7Characteristics of IV Preparations Parenteral IV preparations must have chemical properties that will notdamage vessels or blood cellsalter the chemical properties of the blood serumWith blood, IVs must beiso-osmotic (having the same number of particles in solution per unit volume)isotonic (have the same osmotic pressure, meaning the pressure produced by or associated with osmosis)
8Characteristics of IV Preparations The osmolality is the amount of particulate per unit volume of a liquid preparationmeasured in milliosmoles (mOsm)osmolality of blood serum = 285 mOsm/LAn isotonic solution is a solution in which body cells can be bathed without a net flow of water across a semipermeable membrane0.9% normal saline (NS)
9Characteristics of IV Preparations Pharmacists sometimes must adjust tonicity of parenteral preparations to ensure they are near isotonicA hypertonic solution has a greater number of particles than the blood cells themselves50% dextrose or 3% sodium chlorideA solution of less than normal tonicity is hypotonic, which has fewer numbers of particles than blood cells0.45% NS
10Characteristics of IV Preparations The pH value is the degree of acidity or alkalinity of a solutionacidic solution: pH of less than 7alkaline solution: pH value more than 7Human blood plasma has a pH of 7.4slightly alkalineparenteral IV solutions should have a pH that is neutral (near 7)
11Methods of InjectionThe bolus, or injection, is one of the most common routes of IV administrationThe injection is performed using a syringeprepackaged in the form of filled, disposable plastic syringesinjectable drug must be taken up into the syringe from a single- or multi-dose glass or plastic vial, or from a glass ampuleSometimes the solid drug in the vial has to be reconstituted by addition of a liquid before use
12Methods of Injection IV infusions deliver: large amounts of liquid into the bloodstream over prolonged periods of timeIV infusion is used to deliver:bloodelectrolyteswaterdrugsother fluidsnutrients
13DiscussionWhat are some characteristics of parenteral preparations, and why are they important?
14DiscussionWhat are some characteristics of parenteral preparations, and why are they important?Answer: Tonicity, osmolality, and pH are characteristics of parenteral preparations. It is important that they be adjusted to be as close as possible to the values for human blood, to prevent damage to blood cells and organs.
15Terms to Remember osmotic pressure osmolality isotonic solution hypertonic solutionpH value
16Equipment Used in IV Preparation Pharmacies use plastic disposable products tosave time and moneyprovide the patient with an inexpensive sterile productOften the entire system sent out to the patient floors is composed of plasticthin, flexible plastic catheters are replacing metal shafts that deliver the medication into the veinin many cases the only durable, nondisposable product used to deliver IV medication is the IV pump or controller
17Commonly Used IV Abbreviations: Fluids IV ComponentAbbreviation2.5% dextrose in waterD2.5W5% dextrose in waterD5W5% dextrose and lactated Ringer’s solutionD5RL or D5LR10% dextrose in waterD10W5% dextrose and normal salineD5NS2.5% dextrose and 0.45% normal salineD2.5½ NS5% dextrose and 0.45% normal salineD5 ½ NS
18Commonly Used IV Abbreviations: Fluids IV ComponentAbbreviationnormal salineNS0.45% normal saline0.45%NS or ½ NSlactated Ringer’s solutionRL or LRsterile water for injectionSWFIbacteriostatic water for injectionBWFIsterile water for irrigationSW for irrigationnormal saline for irrigationNS for irrigation
19Commonly Used IV Abbreviations: Electrolytes IV ComponentAbbreviationpotassium chlorideKClpotassium phosphateK phos or KPO4potassium acetateK acetsodium phosphateNa phos or NaPO4sodium chlorideNaCl
20Commonly Used IV Abbreviations: Additives IV ComponentAbbreviationmultivitamin for injectionMVItrace elementsTEzinc (a trace element)Znselenium (a trace element)Se
21Syringes and NeedlesSyringes are used for IV push and in the preparation of infusions, are made of glass or plasticGlass syringes are more expensiveuse limited to medications that are absorbed by plasticPlastic syringesare less expensiveare disposablecome from the manufacturer sterile
22Syringes and Needles Needles are made of stainless steel or aluminum needle lengths range from 3/8 of an inch to 6 inchesneedles come in gauges ranging from 30 to 13 (higher the gauge, smaller the lumen)After use, needles must be discarded in a designated sharps container
23IV SetsAn IV administration set is a sterile, pyrogen-free disposable device used to deliver IV fluids to patientsThe set maybe sterilized before use by means of radiation or ethylene oxidecome in sterile packaging and a sealed plastic wrapSets do not carry expiration datesSets carry the following legend:“Federal law restricts this device to sale by or on the order of a physician.”
24IV Sets Nurses generally have the responsibility for attaching IV tubing to the fluid containerestablishing and maintaining flow rateoverall regulation of the systemPharmacy personnel must assess aspects of IV systems, including infusion setsA complete understanding of IV sets and their operation is important to pharmacists and pharmacy personnel
25IV Sets IV sets are sterile and nonpyrogenic Each unit is supplied in packaging that ensures the maintenance of sterilityFlanges and other rigid parts of an IV set are molded from tough plasticMost of the length of the tubing is molded from a pliable polyvinyl chloride (PVC)PVC sets should not be used fornitroglycerin, which is absorbed by the tubingIV fat emulsions, which may leach out of the tubing
26IV SetsSafetyNoteA damaged package cannot ensure sterility, even if all protectors are in place. It is best to discard sets that are found in unoriginal, opened, or damaged packages.
27IV SetsSafetyNoteDo not use PVC IV sets for nitroglycerin or fat emulsions. Special types of plastic sets are required for such infusions.
28IV SetsThe length of sets varies from 6-inch extensions up to 110- to 120-inch sets used in surgerythe priming of tubing depends on the length of the setStandard sets have a lumen diameter of 0.28 cmvarying the size of the lumen diameter achieves different flow ratesregulation of flow rates is critical in neonates and infants
29IV SetsThe tubing’s interior lumen may contain particles that flush out when fluid is run through the setUse of final filtration has reduced the need for flushing the line with the IV fluid before attaching the set to the patient
30IV SetsA spike to pierce the rubber stopper or port on the IV containerA drip chamber for trapping air and adjusting flow rateA control clamp for adjusting flow rate or shutting down the flowFlexible tubing to convey the fluid
31IV Sets A needle adapter for attaching a needle or a catheter A catheter, or tube, may be implanted into the patient and fixed with tape to avoid having to repuncture the patient each time an infusion is given
32IV Sets Most IV sets contain a Y-site, or injection port a rigid piece of plastic with one arm terminating in a resealable portused for adding medication to the IVSome IV sets also contain resealable in-line filtersprotection for the patient against particulates, including bacteria and emboliGo to to see IV tubing products from a major manufacturer
33IV SetsThe spike is a rigid, sharpened plastic piece used proximal to the IV fluid containercovered with a protective unit to maintain sterilitygenerally has a rigid area to grip while it is inserted into the IV containerIf an air vent is present on a set, it is located below the spikethe air vent points downward and has a bacterial filter coveringthe vent allows air to enter the bottle as fluid flows out of itnecessary for glass bottles without an air tube
34IV SetsThe drip chamber is a transparent, hollow chamber located below the set’s spikedrops of fluid fall into the chamber from an opening at the uppermost end, closest to the spikenumber of drops it takes to make 1 mL identifies an IV set
35IV Sets The most common IV drop sets are 10 (10 gtt/mL)15 (15 gtt/mL)20 (20 gtt/mL)60 (60 gtt/mL)An opening that provides 10, , or 20 gtt/mL is commonly used for adultsAn opening that provides 60 gtt/mL is used for pediatric patients and is called a mini-drip set
36IV SetsThe person administering the fluid starts the flow by filling the chamber with fluid from an attached inverted IV containerthe chamber sides are squeezed and releasedfluid flows into the chamberprocedure is repeated until an indicated level is reached or approximately half the chamber is filledentering drops are counted for 15 secondsadjustments made until approximate number of drops desired is obtainedrate should be checked five times, at 30-second intervals, and again for a last count of 1 minute
37IV SetsClamps allow for adjusting the rate of the flow and for shutting down the flowClamps may be located at any position along the flexible tubingUsually a clamp moves freely, allowing its location to be changed to one that is convenient for the health professional administering the medication
38IV Sets Types of clamps used for IV solutions include: slide clamp: has an increasingly narrow channel that constricts IV tubing as it is pressed further into the narrowed areascrew clamp: consists of a thumbscrew that is tightened or loosened to speed or slow the flowroller clamp: a small roller that is pushed along an inclinemoving down the incline, constricts tubing and reduces fluid flowmoving up the incline, increases the flow
39IV Sets Clamp accuracy can be affected by: The needle adapter creep: tendency of some clamps to return to a more open position with increased fluid flowcold flow: tendency of PVC tubing to return to its previous positionThe needle adapterusually located at the distal end of the IV set, close to the patienthas a standard taper to fit all needles or cathetersis covered by a sterile cover before removal for connection
40IV Sets A set may have a built-in or in-line filter Final filtration should protect the patient against particulate matter, bacteria, air emboli, and phlebitisa 0.22-micron filter is optimala 5-micron filter removes particles that block pulmonary microcirculation but will not ensure sterilityA Y-site is an injection port found on most setsthe Y is a rigid plastic piece with one arm terminating in a resealable portthe port, once disinfected with alcohol, is ready for the insertion of a needle and the injection of medication
41FiltersFilters are devices used to remove contaminants such as glass, paint, fibers, and rubber coreswill not remove virus particles or toxinswill occasionally become clogged, thus slowing expected flow ratesFilter sizes include:5.0 microns – random path membrane (RPM) filter, removes large particulate matter0.45 microns – in-line filter for IV suspension drug0.22 microns – removes bacteria and produces a sterile solution
42CathetersIV administration for fluids and drug therapy can be accomplished through needle-like devices called cathetersCatheters are devices inserted into veins for direct access to the blood vascular system and are used in two primary ways:peripheral venous catheters, which are inserted into a vein close to the surface of the skincentral venous catheters, which are inserted deeper in the body
43CathetersA peripheral venous catheter is inserted into veins close to the surface of the skin and used for up to 72 hoursunit is inserted into a veinneedle portion is withdrawnflexible, Teflon catheter is left in placePeripheral catheters are easy to insert, and most nurses can do this at a patient’s bedsideusually inserted in sites on the arms or handscan be inserted in the feet and scalp if the nurse or physician cannot locate “good” veins in the arms or hands
44CathetersPeripheral venous catheters will likely cause problems 20 to 50% of patientspainirritationinfiltrationInfiltration is a breakdown or collapse of a vein that allows the drug to leak into tissues surrounding the catheter site, causing edema and/or tissue damage
45Catheters A central venous catheter is one placed deep into the body more complicated to placeinserted by a physician to minimize the risk of infectionCentral catheters are commonly used for therapy of 1 to 2 weeks or even longerA central venous catheter is used to administer:hypertonic solutions such as total parenteral nutrition (TPN) solutionspotentially toxic drugs such as cancer chemotherapeutic drugs
46Catheters The most common sites of insertion are subclavian vein, lying below the clavicle and joining the jugular veinjugular vein, in the neckfemoral vein, in the groin areaPlaced deep in the vein so that the end enters the superior vena cava close to the heart where the blood flow is the greatestVisit the Web site of the American Society of Enteral and Parenteral Nutrition, a good source for information and networking
47Catheters Problems with subclavian catheters are: possibility of subclavian vein laceration (i.e., missing the vein and puncturing a lung)greater risk of infection because the procedure is more invasiveA larger blood flow in the subclavian vein will dilute a more concentrated solution such as TPNTPN solutions provideneeded calories in the form of amino acids and dextrosevitamins, minerals, trace elements, and electrolytes
48CathetersA multiple-lumen catheter is used to separately administer potentially physically incompatible drugscomes with one, two, three, or four lumensEach lumen exits the catheter at a different locationno opportunity exists for the drugs to mix before being diluted in the bloodstream
49CathetersMidline catheters are longer peripheral catheters that go from insertion site into a deep veindesigned to stay in place 1 week or longerThe peripherally inserted central (PIC) line is a very fine line that is threaded through the peripheral vein into the subclavian veinhas the same characteristics as a central linecan be inserted by a skilled nurse at the bedside
50CathetersSome patients may be on TPN therapy for months or even years in the hospital or at homeInfusion devices are surgically implanted to:provide long-term therapyreduce the risk of infection
51CathetersImplantable infusion devices include the Hickman and Broviac external cathetersSurgeon inserts the catheter below the breast and tunnels it under the skin into the subclavian veincatheter has a cuff to which the body’s connective tissue heals, sealing off bacterial entrylower point of body insertion makes the catheter easier for the patient to see and clean
52CathetersAnother form of implantable device is the internal port, such as the Port-A-Cath, Life Portwhen implanted the only evidence is a bump in the skindrugs, especially cancer chemotherapeutic drugs, are administered by a small needle through the skin in an injection port in the device
53Pumps and ControllersFluids and drugs are often delivered to catheters by some form of device, including electronic devices, to control the infusion rateThe first system to deliver a drug IV was the syringe systemCare must be taken when administering drugs that have to be diluted or given very slowlyThe syringe system is very nurse labor-intensive and pharmacy labor-intensive
54Pumps and ControllersThe Buretrol or Soluset were in use before infusion pumps and replaced the syringe system and has a built-in graduated cylinderfluid is run into the cylindernurse can add a drug in the top of the cylinder injection port for dilution and mixing before it is infusedSafer than the syringe system because the drug is being diluted in the cylinder and it can be infused over a long period of time
55Pumps and ControllersThe Buretrol or the Soluset have the following problems:labor intensivepotential drug incompatibilitycontrollers are low-pressure devices (2 to 3 psi)pressure of controller is generated by gravityflow rate is controlled by rate of fluid drops falling through a counting chamberalarms sound with a kink in a line or even interruption of blood flow when patient bends an elbow
56Pumps and ControllersInfusion pumps are preferred by both nurses and physiciansproduce a positive pressure of 10 to 25 psiare more accurate than controllershave fewer flow interruptionsInfusion pumps control the flow of IV medicationsMaximum flow is 999 mL/hrprovides a higher rate of infusionhigher pressure increases possibility of infiltration
57Pumps and ControllersA patient-controlled analgesia (PCA) device is a type of medication delivery that uses a parenteral route and allows the patient to administer analgesics by pressing a buttoncontrols the medication so the patient cannot overdose or give the medication too soon after the previous doseOften, after surgery or severe injuries, a physician will order a PCA for the patient for 24 to 72 hours
58Pumps and Controllers Safety Note PCA pumps should carry the following label: “This PCA pump button should be pushed only by the patient.”
59DiscussionWhat is the most important characteristic that all equipment used in IV preparation and administration have in common?
60DiscussionWhat is the most important characteristic that all equipment used in IV preparation and administration have in common?Answer: Sterility is a requirement for all equipment used in IV preparation and administration.
61Terms to Remember IV administration set filter catheter peripheral venous catheterinfiltrationcentral venous cathetersubclavian veinmultiple-lumen catheterperipherally inserted central (PIC) line
62Preparing IVsPharmacists and technicians prepare drugs and IV solutions in a form ready to be administered to a patientIV push (i.e., bolus) and IV infusion dose forms should be prepared in laminar airflow hoods using aseptic techniquesproducts used during the preparation must always be sterile and handled in such a manner as to prevent contamination
63Preparing IVsPreparation should always be done under the supervision of a licensed pharmacistMedication that is prepared by the technician must be reviewed and approved by the pharmacistVisit the ASHP Web site for a standard for quality assurance of sterile products
64IV Preparation Guidelines Begin any IV preparation by washing your hands thoroughly using a germicidal agent such as chlorhexidine gluconate or povidone-iodineAll jewelry should be removed from the hands and wrists before scrubbing and while making a sterile productWear gloves during proceduresLaminar airflow hoods are normally kept runningEating, drinking, talking, or coughing is prohibited in the laminar airflow hoodWorking in the laminar flow hood should be free from interruptions
65IV Preparation Guidelines Before making the product, thoroughly clean all interior working surfacesGather all the necessary materials for the operation and make sure they are:not expiredfree from particulate matter such as dustcheck for leaks by squeezing plastic solution containersOnly essential objects and materials necessary for product preparation should be placed in the airflow hood
66IV Preparation Guidelines Work in the center of the work area within the laminar airflow hoodat least six inches inside the edge of the hoodmake sure nothing obstructs the flow of air from the high- efficiency particulate air (HEPA) filter over the preparation areanothing should pass behind a sterile object and the HEPA filter in a horizontal airflow hood or above a sterile object in a vertical airflow hood
67IV Preparation Guidelines Follow proper procedure for handling sterile devices and medication containersRemember that the plunger and tip of the syringe are sterile and must not be touchedFor greatest accuracy, use the smallest syringe that can hold the desired amount of solutionsyringe should not be larger than twice the volume to be measuredsyringe is considered accurate to half the smallest measurement mark on its barrel
68IV Preparation Guidelines The volume of solution drawn into a syringe is measured at the point of contact between the rubber piston and the side of the syringe barrelAdditives are commonly added to IV solutionsmedications, electrolytes, vitamins and/or mineralsAdditives may be packaged in vials or ampulesProper technique in using vials and ampules is an important skill for the pharmacy technician to learn
69VialsPowders are reconstituted by introducing a diluent (e.g., sterile water for injection)Vials are closed systemsthe amount of air introduced should be equal to the volume of fluid removedan exception to this guideline is the withdrawal of cytotoxic drugs from vials
70VialsSafetyNoteWith the exception of cytotoxic drugs, inject an equal amount of air into the vial with the syringe and needle before withdrawing the medication.
71Use a Syringe to Draw Liquid from a Vial VialsUse a Syringe to Draw Liquid from a VialChoose the smallest gauge needle appropriate for the task, and avoid coring the rubber top of the vial and thus introducing particulate into the liquid within it2. Attach the needle to the syringe.3. Draw into the syringe an amount of air equal to the amount of drug to be drawn from the vial.
72VialsSwab or spray the top of the vial with alcohol before entering the laminar flow hood; allow the alcohol to dry. Puncture the rubber top of the vial with the needle bevel up. Then bring the syringe and needle straight up, penetrate the stopper, and depress the plunger of the syringe, emptying the air into the vial.
73Vials 5. Invert the vial with the attached syringe. Draw up from the vial the amount of liquid required.7. Withdraw the needle from the vial. In the case of a multidose vial, the rubber cap will close, sealing the contents of the vial.8. Remove and properly dispose of the needle, and cap the syringe. A new needle will be attached at the time of injection into a patient.
74Ampules An ampule is a single-dose-only drug container The glass ampule offers another challenge because one must first break the top off the ampule before withdrawing the medication
75Ampules Opening an Ampule Gently tap the top of the ampule to bring the medication to the lower portion of the ampule.
76Ampules Opening an Ampule Clean the neck with an alcohol swab; then grasp the ampule between the thumb and index finger at the neck with the swab still in place.
77Forcefully snap the neck away from you. AmpulesOpening an AmpuleForcefully snap the neck away from you.
78AmpulesTo withdraw from an ampule, tilt the ampule, place the needle bevel of a filter needle or tip of a filter straw in the corner near the opening, and withdraw the medicationUse a needle equipped with a filter for filtering out any tiny glass particles, fibers, or paint chips that may have fallen into the ampule
79AmpulesBefore injecting the contents of a syringe into an IV, the needle must be changed to avoid introducing glass or particles into the admixtureA standard needle could be used to withdraw the drug from the ampule; it is then replaced with a filter device before the drug is pushed out of the syringeFilter needles are for one directional use only
80IV SolutionsMost IV, intrathecal, intra-arterial, and intracardiac injections will be solutionsA diluent is a sterile fluid to be added to a powder to reconstitute or dissolve the medicationcheck the medication package insert to verify which diluent and what volume should be added to the medication vial to make a sterile solutionAlternative routes of administration may also require special preparation, storage, and needlesit is best to check with the pharmacist if such a medication order is received
81IV Solutions The vehicles most commonly used for IV infusions are: dextrose in waterNS solutiondextrose in saline solutionThe two main types of IV solutions are:small-volume parenterals (SVPs) of 50 or 100 mLlarge-volume parenterals (LVPs) of more than 100 mL
82IV SolutionsSVPs are typically used for delivering medications at a controlled infusion rateLarge-volume parenterals (LVPs) are usedto replenish fluidsto provide electrolytes (i.e., essential minerals)to provide nutrients such as vitamins and glucoseLVPs are commonly available in 250 mL, 500 mL, and mL sizes
84IV SolutionsA piggyback is a small-volume parenteral admixture that is attached to an existing IV lineThe piggybacked solution is infused into the tubing of the running IVusually over a short time, from 30 minutes to 1 hourSome IV piggybacks are prepared in 250 mL solution because they contain a medication that is irritating to the veinsIn some cases, syringes are used instead of piggyback containers to deliver medication into a running IV
85IV Solutions A LVP usually contains one or more electrolytes potassium chloride is the most common additiveother salts of potassium, magnesium, or sodium can be addedAdditives to IV solutions can also be multivitamins or trace elements
86Preparing a Label for an IV Admixture Labels for IV admixtures should bear the following information:patient’s name and identification numberroom numberfluid and amountdrug name and strength (if appropriate)infusion periodflow rate (e.g., 100 mL/hr or infuse over 30 min)expiration date and timeadditional information as required by the institution or by state or federal guidelines
87Examples of Pharmacy-prepared Labels for a minibagfor a large-volume parenteral (LVP)
88DiscussionWhat principle guides the techniques and procedures applied to IV solution preparation?
89DiscussionWhat principle guides the techniques and procedures applied to IV solution preparation?Answer: IV preparation is based on aseptic technique and all dosage forms and equipment must be handled in a way that prevents contamination.
91Calculations for the Hospital Pharmacy Technician In preparing sterile IV preparations in the hospital or home healthcare setting, it is important to:understand math skills somewhat unique to these environmentsdouble- and triple-check calculations and flow rates for IV admixtures or TPN solutions
92Calculations for the Hospital Pharmacy Technician Important math skills are needed in the areas ofreading timetemperature and temperature conversionselectrolyte replacement therapyspecific gravityIV infusion flow rates
93Calculations for the Hospital Pharmacy Technician SafetyNoteAlways carefully check and double check all calculations.
94Time ConversionsHospital medication orders are often stamped with international or military timedose administration schedules for unit dose and IV admixtures also use this methodThis time is based on a 24-hour clock, with midnight being considered time 0000time in hours are the first two digitstime in minutes are the last two digitsno A.M. or P.M. are used
96Temperature Conversions The United States is one of the few countries in the world where the Fahrenheit temperature scale is commonly usedThe Fahrenheit temperature scale uses 32° F as the temperature when ice freezes and 212° F as the temperature that water boilsthe difference between these two extremes is 180° F
97Temperature Conversions The Celsius temperature scale is commonly used in Europe and globally in science, and it is often the scale used in the pharmacythe Celsius temperature scale uses 0° C as the temperature when ice freezes and 100° C as the temperature that water boilsthe difference between these two extremes is 100° C
98Temperature Conversions Storing drugs under the proper refrigeration and maintaining refrigerating equipment at the appropriate temperature are responsibilities of the pharmacy technicianmost refrigerators in the pharmacy need to maintain a temperature of 5º C to 10º CTemperatures in the drug package inserts or in the policy and procedure manual are often in centigradepharmacy technicians will need to know how to convert between the Celsius scale and the Fahrenheit scales
99Temperature Conversions Temperature EquivalenciesEvery 5° C change in temperature is equivalent to a 9° F changeCelsiusFahrenheit0º C32º F5º C41º F10º C50º F15º C59º F20º C68º F
100Temperature Conversions These equations allow conversions between the two temperature scales:º F = (1.8 × º C) + 32º C = (º F – 32) ÷ 1.8An alternative method uses this equation:5F = 9C + 160The final temperature is usually rounded up to the closest whole number
101ElectrolytesMany IV fluids used in pharmacy practice contain electrolytes:dissolved mineral saltsso-named because they conduct an electrical charge through the solution when connected to electrodesElectrolytes are measured in millimoles (mM) and milliequivalents (mEq)
102Understanding Millimoles and Milliequivalents Milliequivalents (mEq) are related to molecular weightMolecular weights are based on the atomic weights of elementsthe atomic weight of an element is the weight of a single atom of that element compared with the weight of one atom of hydrogenthe molecular weight of a compound is the sum of the atomic weights of all the atoms in one molecule of the compound
103Understanding Millimoles and Milliequivalents A millimole (mM) is an amount of a substance weighing its molecular weight in milligramsThe valence of an element is a number that represents its capacity to combine to form a molecule of a stable compoundan element can exist in various formsvalence may vary depending on an elemental form
104Valences and Atomic Weights of Common Elements Rounded Valuehydrogen (H)11.008 g1 gcarbon (C)2, 4g12 gnitrogen (N)3, 5g14 goxygen (O)2g16 gsodium (Na)g23 gsulphur (S)2, 4, 6g32.1 gchlorine (Cl)1, 3, 5, 7g35.5 gpotassium (K)g39.1 gcalcium (Ca)40.08 g40.1 gFor pharmaceutical calculations, atomic weights are usually rounded to the nearest tenth (i.e., one unit to the right of the decimal point).
105Understanding Millimoles and Milliequivalents One mole (M) of an element weighs its atomic weight in gramsone mole of sodium (Na) is (rounded to 23 g)Compounds are also measured in molesone mole of salt or sodium chloride (NaCl) would weigh its molecular weight in gramsatomic weight of sodium (23 g) + atomic weight of chlorine (35.5 g) = 58.5 g1 mM is an amount equal to the molecular weight in milligramsbecause 1 g equals 1000 mg, 1 mole equals 1000 mM1 mM of sodium chloride equals 58.5 mg
106Understanding Millimoles and Milliequivalents One equivalent (Eq) is equal to one mole divided by its valenceOne milliequivalent (mEq) is equal to 1 millimole divided by its valencethus one equivalent equals 1000 mEq, or one thousandth of a gram equivalentEquivalent weight = molecular weight (expressed in milligrams) valence
107Determining Milliequivalents of Compounds To determine the number of milliequivalents of a compound:(1) identify the formula of the compound(2) separate the formula into atoms(3) determine the moleclular weight of the compoundmultiply the weight of each atom by the number of those atomsadd the products together, the sum is the molecular weightmEq=molecular weight (expressed in milligrams)valence
108Measuring Electrolytes Milliequivalents (and sometimes millimoles) are used to measure electrolytes in the bloodstream and/or in an IV preparationExample:You must add 44 mEq of sodium chloride (NaCl) to an IV bag. Sodium chloride is available as a 4 mEq/mL solution. How many milliliters will you add to the bag?
109Measuring Electrolytes You must add 44 mEq of sodium chloride (NaCl) to an IV bag. Sodium chloride is available as a 4 mEq/mL solution. How many milliliters will you add to the bag?set up a proportion, comparing the solution you will need to create to the available solution, and solve for the unknown
110Measuring Electrolytes Set up a proportion, comparing the solution you will need to create to the available solution, and solve for the unknownx mL44 mEq=1 mL4 mEq(44 mEq) x mL(44 mEq) 1 mL44 mL411 mL
111weight of an equal volume of water Specific GravitySpecific gravity can be defined as the ratio of the weight of a substance to the weight of an equal volume of water when both have the same temperatureFinal weight can be measured in grams because 1 mL of water weighs 1 g1 mL, volume of water = 1 g, weight of waterspecific gravity of water = 1specific gravity=weight of a substanceweight of an equal volume of water
112Specific GravityWhen the specific gravity is known, certain assumptions can be made regarding the physical properties of a liquidliquids that are viscous or have particles floating in them often have a specific gravity higher than 1solutions that contain volatile chemicals (or something that is prone to quick evaporation), such as alcohol, often have a specific gravity lower than 1
113Specific Gravity Safety Note Usually numbers are not written without units; however, no units exist for specific gravity. Therefore, you must label specific gravity carefully.
114Calculation of IV Rate and Administration IV flow rates are usually described as milliliters per hour or as drops per minute (expressed as gtt/min)pharmacy usually uses milliliters per hournurses sometimes prefer drops per minuteThe formula used to determine the rate in drops per minute is as follows:x gtt/min=(volume of fluid ÷ delivery time in hrs) × (drop rate of administration set)60 min/hr
115Calculation of IV Rate and Administration Example:A physician orders 4000 mL of a 5% dextrose and normal saline (D5NS) IV over a 36-hour period. If the IV set will deliver 15 gtt/mL, then how many drops must be administered per minute?Begin by identifying the amounts to insert into the equation.volume of fluid=4000 mLdelivery time36 hrdrop rate of the administration set15 gtt/mL
116Calculation of IV Rate and Administration x gtt/min=(volume of fluid ÷ delivery time in hrs) × (drop rate of administration set)60 min/hr(4000 mL ÷ 36 hr) × (15 gtt/mL)111 mL/hr) × (15 gtt/mL)27.75 gtt/min, rounded to 28 gtt/min
117Calculation of IV Rate and Administration The number of hours that the IV will last can be determined by dividingthe volume of the IV bag (expressed in milliliters)bythe flow rate (expressed in milliliters per hour)
118Calculation of IV Rate and Administration Example:A 1 L IV is running at 125 mL/hr. How often will a new bag have to be administered?Begin by converting 1 L to 1000 mL, and then divide the volume by the volume per hour rate.hours the IV will last=1000 mL125ml/hr= 8 hr
119DiscussionWhat are some of the special areas of calculations skills that are important for technicians preparing IV solutions?
120DiscussionWhat are some of the special areas of calculations skills that are important for technicians preparing IV solutions?Answer: Skills for accurate conversion between time and temperature systems, electrolyte measurement, specific gravity determinations, and infusion flow rate calculations are vital in IV preparation and labeling.
121Terms to Remember Fahrenheit temperature scale Celsius temperature scaleelectrolytesatomic weightmolecular weightmillimole (mM)valencemole (M)equivalent (Eq)milliequivalent (mEq)