Chapter 6: Dosages of IV Drugs Pharmacology I 1

IV Therapy Overview Directly into bloodstream Advantages – immediate action Disadvantages – potential for severe adverse reactions, fluid overload Prescriber orders rate What are some ideal reasons for an IV infusion? To hydrate a patient, when fluids/drugs are needed in a patient’s system quickly, when fluids/drugs must be given at a steady rate, patient-controlled drugs (e.g., IV drugs for pain), drugs that would not be absorbed if taken by mouth. Fluid overload – accidental infusion of IV fluids at a much faster rate than was ordered, causing harm to the patient–sometimes called a “runaway IV.” Who is responsible not only for giving the correct fluids at the ordered rate, but also for monitoring the patient’s reaction to the IV? The nurse! 2 2

IV Mechanics IV flow rate Drip rate Drop factor Drip chamber Macrodrip, microdrip Drip chamber Administration set The IV flow rate is how fast the IV is prescribed to go – the number of milliliters delivered in 1 hour. The rate of an IV depends on the diameter of the tubing. Would it take more drops or less drops to make 1 mL with fatter tubing? Less Drip rate – depends on diameter of tubing. Drop factor – the number of drops needed to make 1 mL of fluid. Drip chamber – clear cylinder of plastic attached to IV tubing. Administration set – complete set of tubing and drip chamber used to administer a drug intravenously. Microdrip tubing set delivers very small drops and is used for children, older patients, and patients who cannot tolerate a fast infusion rate or a high volume of fluids. Macrodrip set delivers larger drops and is used when fast infusion rates or larger quantities of fluids or drugs are needed. Each manufacturer puts its drop factor (sometimes called drip factor) on every IV fluid administration set. 3

Macrodrip versus Microdrip Figure 6-1. Drop size differences between a macrodrip chamber and a microdrip chamber on IV tubing. 4

Regulating IV Fluids 4 important concepts: Regulators: What (type of fluid to infuse) Volume (of fluid to infuse) Duration (of infusion) Rate (of infusion) Regulators: Controller Infusion pump Roller clamp IV therapy involves determining the drip rate (number of drops per minute needed to make the drug infuse in the prescribed amount of time). List the four IV calculation concepts in the following order: “1000 mL of normal saline to be infused over 8 hours” What: normal saline; Volume: 1000 mL; Duration: 8 hours; Rate: 125 mL per hour (divide volume by duration) Because each brand of control device differs, always read and follow the manufacturer’s directions. 5

Calculating IV Fluids Calculate rate: Total volume of infusion Duration of infusion (in hours) Drop factor (on IV package) Used for control roller or slides Stated in drops per minute Use the particular drop factor of the tubing being used to calculate how many drops per minute are needed to make the drug infuse in the ordered time. All IV rates that are controlled using a control roller or the control slide on the tubing are calculated by drops per minute; others are programmed by computer on the IV pump in mL per hour. 6

IV Calculation Formulas Macrodrip: Microdrip: Much easier! mL per hour = drops per min Use macrodrip formula, but 60s cancel each other out × drop factor = drops per min Macrodrip: An IV of 1000 mL is prescribed to run for 8 hours. Calculate the flow rate. 1000 ÷ 8 = 125 mL/hr. Then calculate how many drops per minute are needed to make the IV infuse at 125 mL per hour (or 125 mL in 60 min). 125/60 × 15 = 2.08 × 15 = 31.2 drops per min (rounded down to 31 drops per min) Microdrip: When using microdrip tubing, the drop factor of 60 drops per mL is the same as the number of minutes in 1 hour (60). Example: 125/60 × 60/1 (drop factor) = 125/1 = 125 drops per min 7

15-Second Rule Drops per min ÷ 4 Regulate roller or slide to release same number of drops in 15 seconds Number of drops in 15 seconds × 4 should be very close to prescribed rate of drops per min Example: if drop rate is 31 gtt/min, 31 ÷ 4 = 7.75; round up to 8. If you count 8 drops in 15 seconds, the IV rate is on time! This method only works for manually controlled IVs, not for those on a pump. 8

Maintaining IV Therapy Always practice within state nurse practice act AND agency policy Prescriber’s order always required for IV therapy and must contain: Specific drug or IV solution to be infused Dosage or volume Duration Rate of infusion IV drug therapy is an invasive procedure that requires a prescriber’s order. In some states, starting an IV can be performed by an LPN/LVN. In other states, it must be an RN. Before starting an IV or giving IV drugs, check the state’s nurse practice act and agency policy to determine your legal scope and expected practice. 9

Infusion Control Devices Controllers Gravity-run system Alarm sounds if malfunction Pumps Rate greater than gravity Better for precision Danger of infiltration or extravasation Syringe pumps Slow IV pushes Many health care settings require a pump or controller be used for all types of IV therapy. The alarm feature is the primary benefit of a controller over a manually administered IV. Syringe pumps are used when the volume of drug to be given by IV “push” is large (but too small for an IVPB bag), or should be given over more than 2 minutes. For example, it would be helpful when IV phenergan must be diluted with normal saline to a volume of 10 mL and then given over a 5- to 10-minute period. 10

IV Therapy Responsibilities Check often: Flow rate Equipment function Site condition Assess for/prevent complications: Infection Tissue damage Fluid and electrolyte imbalances How often checks are performed depends on the type of solution and equipment used, but may be as often as every hour. During each check, determine how much solution has been infused. Ensure that the flow rate and volume being delivered are maintained according to the prescriber’s order. 11

IV Site Infection Signs and symptoms: If infection suspected: Redness Heat Pain around site Wound drainage Fever (if infection becomes systemic) If infection suspected: Remove needle, document, notify prescriber Apply ice or heat Apply sterile dressing with antibiotic ointment Signs and symptoms of IV therapy-related infections may not be obvious until 24 hours after the infection begins. Check the insertion site at least every 4 hours for redness and heat, and ask the patient about any discomfort at the site. What are the most common organisms causing IV therapy-related infections? Those that are normally present on the skin, often including the antibiotic-resistant bacteria MRSA Why should the prescriber be notified? So additional treatment related to the infection can be prescribed 12

Tissue Damage Skin (bruising and clot formation) Veins (chemical trauma) Causes – hypertonic solutions, potassium chloride, antibiotics, calcium, magnesium, alcohol, vasoconstrictive drugs, chemotherapy drugs Phlebitis Thrombophlebitis Subcutaneous tissue Infiltration Extravasation May be temporary or permanent, and is avoidable. How is skin damaged? By trauma when improperly starting or removing an IV. How are veins damaged? Result of chemical trauma related to the type and concentrations of IV solutions, as well as to infusion rate. Infiltration occurs when chemically irritating IV fluids or drugs (vesicants) leak into subcutaneous tissues causing tissue damage. Drugs that constrict blood vessels can lead to tissue necrosis when infiltration occurs. Prevent infiltration or extravasation by checking the IV site at least every 2 hours to ensure that the needle is completely in the vein. (When a vesicant drug is infusing, check the site hourly.) 13

Infiltration From Hockenberry, M.J., & Wilson, D. (2006). Wong’s Nursing Care of Infants and Children (8th ed.). St. Louis: Mosby. Figure 6-5. Appearances of tissues after IV infiltration (A). 14

Extravasation with Tissue Necrosis From Weinzweig, J. & Weinzweig, N. (2005). The Mutilated Hand, St. Louis: Mosby. Figure 6-5. Appearances of tissues after extravasation (B). 15

Fluid and Electrolyte Imbalance Fluid overload signs and symptoms: Rapid pulse, elevated blood pressure Bulging hand veins, neck veins when upright Shortness of breath Coughing Pitting edema Electrolyte imbalances Too much IV fluid can dilute blood electrolytes Rapid infusion of electrolytes can increase blood levels to life-threatening levels Report any of fluid and electrolyte imbalance signs and symptoms immediately! IV therapy involves infusion of fluids directly into the bloodstream, so the risk for rapid changes in blood volume and composition is great. Fluid overload is the most common imbalance among patients receiving IV therapy. Factors leading to fluid overload include position changes of the patient or the IV bag, infusing IV fluids without using a controller or a pump, or a change made in the infusion rate by patients or visitors. Electrolyte imbalances may result in blood electrolyte levels that are too low or too high. IV fluid containing potassium should always be given with a controller or pump. 16

Life Span Considerations Pediatric: Difficulty accessing IV sites More likely to dislodge needle Narrow range of normal fluid volume ALWAYS use microdrip tubing and volume-controlled IV administration set Older patients: Difficulty starting and maintaining IVs At risk for fluid volume overload For infants, veins on the scalp are most commonly used for IV therapy, and for younger children, the top of the foot is a common site. In older adults, the skin on the forearm and hand may be thin and fragile from sun exposure and age. In addition, veins lose elasticity and become fragile as a person ages, making vein damage more likely. Always use a controller or pump with older patients to prevent accidental rapid infusion. Check every hour for signs and symptoms of fluid overload. 17

KEY POINTS The rate of an IV infusion depends on the diameter of the tubing. The larger the diameter of IV tubing, the larger the drops. Report signs and symptoms of fluid overload (rapid pulse, elevated blood pressure, bulging hand and neck veins, shortness of breath, coughing, and pitting edema) in a patient receiving IV therapy to the prescriber or the charge nurse immediately. Because each brand of IV pump or control device differs, always read and follow the manufacturer's directions. Always calculate both the start and stop times and then time- tape the IV bag, even when it is on a controller or pump. Never speed up an IV to make up for lost time when the infusion is behind schedule.

KEY POINTS An IV controller works by gravity and only controls the rate that the fluid drips into the vein. A pump actually forces drops. Thus, if an infiltration has occurred, a controller stops, but a pump can continue to push IV fluid into the surrounding tissue. Always double check the order before starting an IV infusion. Signs and symptoms of phlebitis include burning and pain at the site, reddened and warm areas, or hard streaks that follow the vein path. Signs and symptoms of infiltration include pain or burning at the IV site, paleness of the skin, coolness or warmth around the site, lack of blood return, and leakage around the needle.

KEY POINTS A prescriber's order is not required to discontinue an IV that is infiltrated or infected at the insertion site. Always use a controller or pump with IV fluids that contain potassium. Use a controller or pump when giving IV fluids to an older adult. Use a volume-controlled IV administration set when giving IV fluids to infants and young children.