Calculating Heparin Bolus Dosage and IV Rate Rule 18-6 To determine the rate (mL/h) at which to administer a solution containing heparin, find A, where D = rate of the desired dose Q = dosage unit H = dose on hand A = amount to administer . Learning Outcome: 18.4 Calculate heparin bolus dosage and IV rate with and without a weight-based heparin protocol. Calculate using your chosen calculation method: proportion method or dimensional analysis.

IV and Bolus Heparin Calculations Ordered: 1000 units/h IV heparin using an infusion pump On hand: 25,000 units heparin in 500 mL D5W H = 25,000 units; Q = 500 mL; D = 1000 units/h Step A No conversion is needed. Example Learning Outcome: 18.4 Calculate heparin bolus dosage and IV rate with and without a weight-based heparin protocol. Both dose on hand and dose ordered are in units.

IV and Bolus Heparin Calculations – Dimensional Analysis Step B Calculate A mL/h = 500 mL / 25,000 units x 1000 units / 1 hr A mL/h = 500,000 mL/ 25,000 hr A mL/h = 20 mL / h Example Learning Outcome: 18.4 Calculate heparin bolus dosage and IV rate with and without a weight-based heparin protocol. Unit of measure for amount to administer is mL/h. A mL/h on one side of the equation First factor: dosage unit and dose on hand 500mL/25,000 units Second factor: 1000 units/ 1 h Cancel units – remaining units should match units on other side of equation. Solve Can also be done by proportion method. See example in text.

IV and Bolus Heparin Calculations Step C Think!…Is It Reasonable? Since the dosage strength of a 25,000 unit / 500 mL solution is 50 units / 1 mL, and 50 x 20 is 1000, it is reasonable. Example Learning Outcome: 18.18.4 Calculate heparin bolus dosage and IV rate with and without a weight-based heparin protocol. What is the relationship between the dose ordered and dose on hand?

IV and Bolus Heparin Calculations (cont.) To ensure the maximum and/or safe dose is not exceeded determine the hourly dose of a heparin infusion. Learning Outcome: 18.4 Calculate heparin bolus dosage and IV rate with and without a weight-based heparin protocol.

IV and Bolus Heparin Calculations (cont.) Rule 18-7 To calculate the hourly dose (D), determine the following: H = dose on hand or total amount to administer Q = dosage units for total amount A = amount to administer or flow rate of infusion Learning Outcome: 18.4 Calculate heparin bolus dosage and IV rate with and without a weight-based heparin protocol. Calculate using your chosen calculation method: proportion method, dimensional analysis, or formula method.

IV and Bolus Heparin Calculations What is the hourly dose? Ordered: 25,000 units of IV Heparin in 500 mL to D5W to infuse at 1000 units/h H = 25,000 units; Q = 500 mL; A = 25 mL/h D = ? (hourly or desired dose) Step A No conversion is needed. Example Learning Outcome: 18.18.4 Calculate heparin bolus dosage and IV rate with and without a weight-based heparin protocol.

IV and Bolus Heparin Calculations – Proportion Method Step B Calculate H = 25,000 units; Q = 500 mL; A = 25 mL/h 25,000 units : 500 ml = D : 25 ml/h 500 x D = 25,000 units x 25 1 /h 500D/500 = 625,000 units 1/h/500 D = 1250 units/h Example Learning Outcome: 18.4 Calculate heparin bolus dosage and IV rate with and without a weight-based heparin protocol. Set up equation. Cancel units. Solve for D. Can also be done by dimensional analysis. See example in text.

IV and Bolus Heparin Calculations – All Methods Step C Think!…Is It Reasonable? The dosage strength of 25,000 units / 500 mL provides 50 units /1 mL, and 50 x 25 = 1250. It is reasonable. Example Learning Outcome: 18.4 Calculate heparin bolus dosage and IV rate with and without a weight-based heparin protocol. What is the relationship between the dose ordered and dose on hand?

IV and Bolus Heparin Calculations Example Determine if 1500 units / h is a safe dose. 1250 units/1 hr x 24 h/1 day = 30,000 units/day Safe dose range for 24 h is 20,000 to 40,000 units. So 30,000 units per day is a safe dose. Learning Outcome: 18.18.4 Calculate heparin bolus dosage and IV rate with and without a weight-based heparin protocol.

Practice What is the hourly dosage for an infusion of 45,000 units heparin in 1200 mL of D5W infusing at 30 mL/h? Is this a safe dose? A = 1125 units/h Is this a safe dose? This is a safe dose. Learning Outcome: 18.4 Calculate heparin bolus dosage and IV rate with and without a weight-based heparin protocol. Step A No conversion is needed. Step B A units/h = 45,000 units / 1200 mL x 30 mL / 1 h Cancel units – mL Solve : 45000 units x 30 / 1200 x 1 h A units/h = 1,350,000 units/ 1200 h A units/h = 1125 units / hr Step C The dosage strength of 45,000units / 1200 mL = 37.5 units/ 1 mL 13.5 x 30 = 1125, so it is reasonable. 1125 units / 1 h x 24 h / d = 27,000 units per day. It is a safe dose.

IV and Bolus Heparin Calculations (cont.) Heparin protocol Preprinted order set to guide administration of IV heparin based on: weight serum activated partial thromboplastin time (aPTT) Bolus initial dose given to achieve therapeutic blood level of heparin Learning Outcome: 18.18.4 Calculate heparin bolus dosage and IV rate with and without a weight-based heparin protocol.

IV and Bolus Heparin Calculations (cont.) Heparin protocol Maximum dose is provided. Infusion rate and subsequent changes are based on weight in kilograms. Learning Outcome: 18.18.4 Calculate heparin bolus dosage and IV rate with and without a weight-based heparin protocol. Protocols will provide a maximum dose. This prevents patient from receiving a toxic dose of heparin. This is used if calculated dose exceeds the maximum dose.

IV and Bolus Heparin Calculations Calculate initial bolus dose of 80 units /kg (maximum dose: 8,000 units). Patient weight = 154 lb Step A Convert patient weight. 1 kg/2.2 lb = x/154 lb 2.2 x x = 154 X 1 kg x = 154 / 2.2 x = 70 kg Example Learning Outcome: 18.18.4 Calculate heparin bolus dosage and IV rate with and without a weight-based heparin protocol. Conversion factor is 1 kg / 2.2 lb. Cancel units. Solve.

IV and Bolus Heparin Calculations – Proportion Method Step B Calculate bolus dose using Proportion Method. 80 units: 1 kg = A : 70 kg 1 x A = 80 units x 70 A = 5600 units Example Learning Outcome: 18.18.4 Calculate heparin bolus dosage and IV rate with and without a weight-based heparin protocol. Set up equation. Cancel units (kg). Solve.

IV and Bolus Heparin Calculations – Formula Method Step B Calculate amount to administer. H = 1000 units Q = 1 mL D (bolus) = 5600 units 5.6 x 1 mL = 5.6 mL = A Example Learning Outcome: 18.18.4 Calculate heparin bolus dosage and IV rate with and without a weight-based heparin protocol. Set up equation. Cancel units (units). Solve.

IV and Bolus Heparin Calculations Step C Think!…Is It Reasonable? Desired dose of 5600 units is 5.6 times larger than dose on hand (1000 units). It is reasonable! Example Learning Outcome: 18.18.4 Calculate heparin bolus dosage and IV rate with and without a weight-based heparin protocol. What is the relationship between the dose ordered and dose on hand? Problem can also be calculated using proportion method and dimensional analysis. See examples in text.

IV and Bolus Heparin Calculations (cont.) Rule 18-8 To find the heparin flow rate based on weight: Convert the weight to kilograms. Determine desired dose. Calculate amount to administer. Calculate flow rate. Learning Outcome: 18.4 Calculate heparin bolus dosage and IV rate with and without a weight-based heparin protocol.

IV and Bolus Heparin Calculations – Weight-Based Patient’s weight: 70 kg Desired dose: (D/h) 18 units/kg/h Dosage strength (H/Q) 25,000 units/500 mL Step A: Weight is in kg, so no conversion is needed. Example Learning Outcome: 18.4 Calculate heparin bolus dosage and IV rate with and without a weight-based heparin protocol. Desired dose and dosage strength gotten from protocol (Figure 18-1)

IV and Bolus Heparin Calculations – Weight-Based Patient’s weight: 70 kg Desired dose: (D/h) 18 units/kg/h Dosage strength (H/Q) 25,000 units/500 mL Step B Calculate desired dose: 18 units: 1kg = D : 70 kg 1 x D = 18 units x 70 D = 1260 units / h Example Learning Outcome: 18.4 Calculate heparin bolus dosage and IV rate with and without a weight-based heparin protocol. Desired dose and dosage strength gotten from protocol (Figure 18-1) Step A No conversion is needed. Set up proportion. Cancel units. Solve.

IV and Bolus Heparin Calculations – Weight-Based Step C Think!…Is It Reasonable? 1260 units / h is less than maximum dosage of 1800 units / h listed on the protocol. It is reasonable. Example Learning Outcome: 18.4 Calculate heparin bolus dosage and IV rate with and without a weight-based heparin protocol.

IV and Bolus Heparin Calculations (cont.) Patient’s weight: 70 kg Desired dose: (D/h) 1260 units / h Dosage strength (H/Q): 25,000 units/500mL or 50 units/mL Step A Convert units/h to mL/ h. Example Learning Outcome: 18.4 Calculate heparin bolus dosage and IV rate with and without a weight-based heparin protocol. Desired dose and dosage strength gotten from protocol (Figure 18-1)

IV and Bolus Heparin Calculations (cont.) Step B Calculate flow rate. H/Q = D/A 50 units/1 mL = 1260 units/h/A 1 mL x 1260 1/h = 50 x A 1265 mL/h/50 = 50A/50 A = 25.2 mL/ h Example Learning Outcome: 18.4 Calculate heparin bolus dosage and IV rate with and without a weight-based heparin protocol. Fill in formula. Cancel units. Solve. Most infusion pumps can be set to infuse to the tenth mL.

IV and Bolus Heparin Calculations (cont.) Loading dose = 5600 units administered as 5.6 mL IV push using a heparin concentration of 1000 units/mL. The infusion will be started at 1260 units/h which is 25.2 mL/h using a heparin concentration of 25,000 units/500 mL. Example Learning Outcome: 18.4 Calculate heparin bolus dosage and IV rate with and without a weight-based heparin protocol. Desired dose and dosage strength gotten from protocol (Figure 18-21)

IV and Bolus Heparin Calculations (cont.) Step C Think!...Is It Reasonable? Verify rate by finding mL/h of 1 unit/kg/h and multiplying it by 18 (desired rate). 1 units/kg/h = 70 units/h 70 units/h = 1.4 mL/h 1.4 mL/h x 18 =25.2 mL/h The infusion rate is reasonable. Example Learning Outcome: 18.4 Calculate heparin bolus dosage and IV rate with and without a weight-based heparin protocol.

IV and Bolus Heparin Calculations – Weight-based Adjustment Infusion at 25.5 mL/h aPTT result is 120 sec, so rate must be decreased by 2 units/kg/h Volume for 1 u/kg/h = 1.4 mL/h Example Learning Outcome: 18.4 Calculate heparin bolus dosage and IV rate with and without a weight-based heparin protocol. Refer to protocol Figure 18-21. Volume for 1 u/kg/h already calculated to be 1.4 mL/h (prior example)

IV and Bolus Heparin Calculations – Weight-based Adjustment Multiply by number of units of rate change. 1.4 ml/h x 2 (2 units/kg/h) = 2.8 mL/h Subtract 25.2 mL/h – 2.8 mL/h New infusion rate = 22.4 mL/h Example Learning Outcome: 18.4 Calculate heparin bolus dosage and IV rate with and without a weight-based heparin protocol. Refer to protocol Figure 18-21.

Practice Patient’s weight: 75 kg Desired dose: (D/h) 18 units/kg/h Dosage strength (H/Q) 25,000 units heparin /500 mL (50 units/1 mL) What is the desired dose? What is the flow rate? Learning Outcome: 18.18.4 Calculate heparin bolus dosage and IV rate with and without a weight-based heparin protocol. Step A No conversion is needed. Step B 18 units/1 kg = D/75 kg [cancel units (kg)] 1 x D = 18 units x 75 D = 1350 units / h Step C – It is less than protocol of maximum of 1800 units/h, so it is reasonable. Calculate flow rate. 50 units/1 mL = 1350 units /A [cancel units (units)] 1 mL x 1350 = 50 x A 27 mL/h = A Step C 1 unit/kg/h = 75 units/h x 18 = 1350 units /h, so it is reasonable. ANSWER: 1350 units / h ANSWER: 27 mL/ h