Math and Dosage Calculations for Health Care Third Edition Booth & Whaley

1. Math and Dosage Calculations for Health CareThird EditionBooth & Whaley Chapter 10: Intravenous Dosages McGraw-Hill

2. Learning Outcomes 10.1 Identify the components and concentrations of IV solutions. 10.2 Distinguish basic types of IV equipment. 10.3 Calculate IV flow rates for both electronically controlled and manually controlled IV devices. 10.4 Adjust the flow rate for IV infusions.

3. Learning Outcomes(cont.) 10.5 Calculate infusion time based on volume and flow rate. 10.6 Calculate volume based on infusion time and flow rate. 10.7 Reconstitute and calculate medication for intermittent IV infusions.

4. Introduction • Intravenous(IV) fluids • Delivered directly into the bloodstream via a vein • Includes • Solutions • Medications • Blood • Rapid effect Results can be fatal if wrong medication or dosage is given.

5. IV Solutions – FUNCTIONS • Replacement • Electrolytes • Fluids • Maintenance • Fluid balance • Electrolyte balance • KVO fluids • Keep Vein Open • Maintain an IV line • Therapeutic– Delivers medication to patient

6. IV Solutions – IV LABELS • Solution labels • Name of components • The exact amount of components

7. IV Solutions – IV LABELS (cont.) Rule 10-1In abbreviations for IV solutions: Letters identify components Numbers identify concentration

8. IV Solutions – IV LABELS (cont.) 5% dextrose in Lactated Ringer’s solution might be abbreviated in any of the following ways: • D5LR • D5LR • 5% D/LR • D5%LR Example

9. IV Solutions – COMMONLY USED ABBREVIATIONS

10. IV Solutions – COMMONLY USED ABBREVIATIONS (cont.)

11. IV Solutions – IV CONCENTRATIONS • 5% Dextrose – contains 5 g of dextrose per 100 mL • Normal saline • 0.9% saline • Contains 900 mg, or 0.9 g, of sodium chloride per 100 mL. • ½ Normal saline • 0.45% saline • Contains 450 mg, or 0.45 g, of sodium chloride per 100 mL

12. Choice of solution is based on patient requirements Isotonic IV solutions Do not affect fluid balance of cells and tissues D5W, NS, LR IV Solutions – IV CONCENTRATIONS (cont.)

13. IV Solutions – IV CONCENTRATIONS (cont.) • Hypotonic IV solutions • Move fluid into surrounding cells and tissues • Restore proper fluid level in cells and tissues • Used to correct dehydration • 0.45% NS, 0.3% NS

14. IV Solutions – IV CONCENTRATIONS (cont.) • Hypertonic IV solutions • Draw fluid from cells and tissues into blood stream • Used to correct severe fluid shifts (burns) • 3% Saline

15. IV Solutions – IV CONCENTRATIONS (cont.) Rule 10-2 Patients with normal electrolyte levels are likely to receive isotonicsolutions. Patients with high electrolyte levels will receive hypotonic solutions. Patients with low electrolyte levels will receive hypertonicsolutions.

16. IV Solutions – COMPATIBILITY • Additives • Medications, electrolytes, and nutrients • If not prepackaged, will have to mix.

17. IV Solutions – COMPATIBILITY (cont.) Rule 10-3 Before combining any medications, electrolytes, or nutrients with an IV solution, be sure the components are compatible.

18. IV Solutions – COMPATIBILITY (cont.)

19. Primary Line Bag or bottle of IV solution – 500 mL or 1000 mL Tubing Drip chamber Clamp – regulate IV Injection ports Add medication or compatible fluid Attach a second line IV Equipment

20. Roller clamp Injection ports Drip chamber

21. IV Equipment (cont.) • Tubing • Macrodrip • Larger drops in drip chamber • Infusion rates of 80 mL/h or more • Microdrip • Smaller drops in drip chamber • Infusion rates less than 80 mL/h and KVO • Pediatric and critical care IV’s

22. IV Equipment – MONITORING • Manually • Hang the bag hung 36 inches above patient’s heart • Adjust flow rate using roller or screw clamps • Usually adjusted in gtt/min

23. Electronic devices Rate controllers Gravity Pincher maintains flow rate Alarm sounds when preset flow rate is not maintained IV Equipment –MONITORING (cont.)

24. IV Equipment – MONITORING (cont.) • Infusion pumps • Apply pressure to deliver set volume per minute • Sensor /alarm • Improper rate • Empty bag • Must monitor site for infiltration

25. IV Equipment – MONITORING (cont.) • Syringe pumps • Syringe is inserted into pump • Incompatible medications or fluids • Pediatric doses • Provide precise controlover rate

26. IV Equipment – MONITORING (cont.) • Patient-Controlled Analgesia (PCA)Device • Patient controls medication within preset limits per physician’s order • Records number of times button is pushed • Used to monitor effectiveness of pain relief prescription

27. IV Equipment – MONITORING (cont.) • Volume control sets • Improveaccuracy of • Manual IV setups • Electronic rate controllers • Small volumes of fluids or medications • Uses: pediatric or critical care IVs • Examples: Buretrol, Soluset, and Volutrol

28. Peripheral and Central IV Therapy • Peripheral IV Therapy • Accesses the circulatory system through a peripheral vein • Hand, forearm, foot, leg • Scalp vein in infants

29. Peripheral and Central IV Therapy(cont.) • Central IV Therapy • Central lineprovides direct access to major veins • Used when patient needs: • Large amounts of fluids • A rapid infusion of medication • Infusion of highly concentrated solutions • Long-term IV therapy

30. Peripheral and Central IV Therapy(cont.) • Central IV Therapy • PICC – peripherally inserted central catheter • Inserted into arm vein and threaded into a central vein • Port-A-Cath • Surgically placed under the skin for access to central vein • Accessed through the skin • For intermittent use

31. Peripheral and Central IV Therapy(cont.) Rule 10-4 Never flush a sluggish IV with a syringe. May push a clot into the circulatory system

32. Pain or swelling at the site Infiltration Needle or catheter becomes dislodged from the vein Fluid infuses into the surrounding tissues Signs Swelling Discomfort Coolness at the infiltration site Sizeable decrease in flow rate Peripheral and Central IV Therapy (cont.)

33. Phlebitis Inflammation of the vein Causes Irritation by IV additives Movement of needle or catheter Long-term IV therapy Signs / Symptoms Pain at or near site Heat Redness Swelling at site Peripheral and Central IV Therapy(cont.)

34. Peripheral and Central IV Therapy (cont.) • Treatment of infiltration or phlebitis • Stop IV infusion • Restart in a different site

35. Practice Matching: Isotonic Hypotonic Hypertonic Central line Phlebitis Infiltration PCA Macrodrip Microdrip • 60 gtt/mL • Patient controls medication • Fluid infuses into tissues • For normal electrolyte levels • PICC • For high electrolyte levels • 15 gtt/min • Inflammation of a vein • For low electrolyte levels D F I E H C B G A

36. Flow rate - how fast the IV infuses Calculated from Amount of fluid to be infused Length of time for infusion Expressed as milliliters per hour Calculating Flow Rates mL/h

37. Calculating Flow Rates (cont.) Rule 10-5 To calculate flow rates in milliliters per hour, identify the following: V(volume) – expressed in milliliters T (time) – expressed in hours (convert units as necessary) F(flow rate) – rounded to nearest tenth Use the formula method with or dimensional analysis to determine the flow rate in milliliters per hour.

38. Calculating Flow Rates (cont.) Find the flow rate Ordered: 500 mg ampicillin in 100 mL NS to infuse over 30 minutes Convert minutes to hour: 30 ÷ 60 = 0.5 hr Flow rate = 200 mL/hr Example

39. Manually regulated IVs Calculated as gtt/min Macrodrip Larger drops Drop factors: 10 gtt/mL, 15 gtt/mL, or 20 gtt/mL Microdrip tubing Smaller drops Drop factor: 60 gtt/mL Calculating Flow Rates (cont.)

40. Calculating Flow Rates (cont.) Rule 10-6 To determine the flow rate (f) in drops per minute: 1. Change the flow rate mL/h (F) to gtt/min (f) using the formula: F = flow rate; mL/hr C = calibration factor of tubing; gtts/mL 60 = number of minutes in 1 hour 2. Round to nearest whole number.

41. Calculating Flow Rates (cont.) Example Find the flow rate in drops perminute that is equal to 35 mL/hour using 60 gtt/mL microdrop tubing. f = 35 gtt/min

42. Calculating Flow Rates (cont.) • Counting drops is not precise • Check IV hourly to see if it is on schedule • Before adjusting the rate, check facility policy

43. Calculating Flow Rates (cont.) Rule 10–7To adjust the flow rate: Recalculate the infusion using the volume remaining in the IV and the time remaining in the order. Check the guidelines at your facility before adjusting the flow rate.

44. Calculating Flow Rates (cont.) Example Original Order: 1500 mL NS over 12 hours The IV was infusing at an original rate of 42 gtt/min using 20 gtt/mL macrodrip tubing. After 3 hours, 1200 mL remain in the bag. Flow rate adjustments must not exceed 25%.

45. Calculating Flow Rates (cont.) Example (cont.) Use formula f = 44 gtt/min 25% of original rate of 42 gtt/mL = 10.5 Rate can be adjusted up or down within a range of 32.5 to 52.5 gtt/min. Rate can be adjusted to 44 gtt/min.

46. Practice Calculate flow rate then determine if an adjustment is necessary. Adjustment cannot exceed 25%. Ordered: 250 mL NS over 2 hours (10 gtt/mL tubing) After 30 minutes 100 mL infused.

47. Practice Answer 25% of 21 = 5.25 Adjustment range = 15.75 to 26.75 You may adjust this infusion. Original drop rate f = 21 gtt/min Adjusted rate f = 17 gtt/min

48. Infusion Time and Volume • If not specified in the order you may have to calculate • Duration – if fluid volume and flow rate is known • Fluid volume – if the duration and flow rate is known

49. Infusion Time and Volume (cont.) Rule 10-8 To calculate infusion time in hours (T), identify the: V(volume) expressed in milliliters F (flow rate) expressed in milliliters per hour Fractional hours by multiplying by 60 Use this formula or dimensional analysis to find T, the infusion time in hours.

50. Infusion Time and Volume (cont.) Example Find the total time to infuse. Ordered: 1000 mL NS to infuse at a rate of 75 mL/h T = 13.3 Total time to infuse the solution = 13 hours and 20 minutes