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Chapter 10: Intravenous Dosages

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1 Chapter 10: Intravenous Dosages
Math and Dosage Calculations for Health Care Third Edition Booth & Whaley Chapter 10: Intravenous Dosages McGraw-Hill

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

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

4 Results can be fatal if wrong medication or dosage is given.
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 10-1 In abbreviations for IV solutions: Letters identify components Numbers identify concentration

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

D10W 10% dextrose in water D5W 5% dextrose in water W; H2O Water NS; NSS Normal saline (0.9% NaCl) LR Lactated ringer’s RL Ringer’s lactate

½ NS; ½ NSS One-half normal saline solution (0.45% NaCl) 1/3 NS; 1/3 NSS One-third normal saline solution (0.3% NaCl) ¼ NS; ¼ NSS One-fourth normal saline solution (0.225% NaCl)

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

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 isotonic solutions. Patients with high electrolyte levels will receive hypotonic solutions. Patients with low electrolyte levels will receive hypertonic solutions.

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.)
Examples of incompatible medications/solutions Ampicillin D5W Cefotaxime sodium Sodium bicarbonate Diazepam Potassium chloride Dopamine HCl Penicillin Heparin Vitamin B complex Lactated Ringer’s Tetracycline Calcium chloride

19 IV Equipment 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

20 Roller clamp Injection ports Drip chamber

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

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 control over 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 Improve accuracy 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 line provides 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.)
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 Peripheral and Central IV Therapy (cont.)
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

33 Peripheral and Central IV Therapy (cont.)
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

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 D 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 F I E H C B G A

36 Calculating Flow Rates
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 mL/h

37 Calculating Flow Rates (cont.)
Rule 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 Calculating Flow Rates (cont.)
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

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 per minute 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 10–7 To 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 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

51 Infusion Time and Volume (cont.)
Example Find the total time to infuse. Ordered: 750 mL LR to infuse at a rate of 125 mL/hr started at 11 p.m. T = 6 The total time to infuse is 6 hours.

52 Infusion Time and Volume (cont.)
Rule 10-9 To calculate the time when an infusion will be completed, You must know: 1. The time the infusion started in military time 2. The total time in hours and minutes to infuse the solution ordered

53 Infusion Time and Volume (cont.)
Rule 10-9 (cont.) Since each day is only 24 hours long, when the sum is greater than 2400 (midnight), you must start a new day by subtracting 2400. This will determine the time of completion, which will be the next calendar day.

54 Infusion Time and Volume (cont.)
Example Determine when the infusion will be completed. Ordered: 750 mL LR to infuse at a rate of 125 mL/hr and was started at 11 p.m. on 08/04/08 Infusion time = 6 hours 11 p.m. = 2300 hrs hours = 0500 or 5:00 a.m. on 08/05/08

55 Infusion Time and Volume (cont.)
Rule To calculate infusion volume: Use the formula V = T x F or dimensional analysis to find V the infusion volume in mL. T (time) must be expressed in hours F (flow rate) must be expressed in milliliters per hour

56 Infusion Time and Volume (cont.)
Example Find the total volume infused in 5 hours if the infusion rate is 35 mL/h. V = 5 h × 35 mL/h V = 175 mL 175 mL will infuse in 5 hours

57 Infusion Time and Volume (cont.)
Example Find the total volume infused in 12 hours if the infusion rate is 200 mL/h. V = 12 h × 200 mL/h V = 2400 mL 2400 mL will infuse in 12 hours

58 Intermittent IV Infusions
IV medications may be administered intermittently with or without continuous IV therapy. Delivered through IV secondary line Saline Heparin lock

59 Intermittent IV Infusions – SECONDARY LINES
“Piggyback” or IVPB IV setup attaches to a primary line Infuse medications or other compatible fluids on an intermittent basis IVPB bags are smaller: 50, 100, or 150 mL

Saline or heparin locks An infusion port attached to an already inserted IV needle or catheter. Allow direct injection of medication or infusion of IV medications.

No continuous flow of fluids Requires flushing 2 to 3 times per day Saline lock – uses saline as the flush Heparin lock – uses heparin, an anticoagulant, as the flush

62 Intermittent IV Infusions (cont.)
Preparing and Calculating Intermittent Infusions Flow rate is calculated the same as regular IV infusions. Amount of fluid may be less and time to infuse may be less than an hour. To calculate the flow rate you will need to change the number of minutes into hours.

63 Intermittent IV Infusions (cont.)
Rule When preparing medication for an intermittent IV infusion: Reconstitute the medication using the label and package insert. Calculate amount to administer and the flow rate.

64 Intermittent IV Infusions (cont.)
Example Ordered: Eloxatin 75 mg in 250 mL D5W IV piggyback over 90 minutes Reconstitute with 20 mL of water for injection. Dosage strength – see label Calculate the amount to administer and the flow rate.

65 Intermittent IV Infusions (cont.)
Example (cont.) Amount to administer Flow rate using 15 mL mL A = 15 mL F = 177 mL/h 65

66 Practice Find total infusion time: Ordered: 650 mL 0.45 NS at 40 mL/h started at /09/08 T = hours Total infusion time = 16 hr 15 min When will this IV be completed? 7:30 p.m. 08/09/08

67 Practice Find the volume to administer:
Ordered: D5NS at 65 mL/hr for 8 hours V = 8 h x 65 mL/h V = 520 mL Ordered: NS at 100mL/h for 45 min V = 0.75 h x 100 mL/h V = 75 mL

68 Apply Your Knowledge Identify four functions of IV fluids. ANSWERS
Replacement Maintenance KVO Therapeutic

69 Apply Your Knowledge How many mg of sodium chloride is in 100 mL of normal saline? How many mg of sodium chloride is in 100 mL of 0.45% NS? ANSWER mg NaCl ANSWER mg NaCl

70 Apply Your Knowledge When you adjust the IV flow rate, what percentage of the original flow rate should you not exceed? Flushing a sluggish IV will not cause harm. True / False ANSWER 25% Flushing may push a clot into the circulatory system causing an obstruction.

71 End of Chapter 10 Wisdom consists of the anticipation of consequences.
~ Norman Cousins

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