Advanced Adult Intravenous Calculations Nurses are becoming increasingly more responsible for the administration of IV medications in the critical care areas as well as on general nursing units. Patients in life-threatening situations require thorough and timely interventions that frequently involve specialized, potent drugs.

IV Flow Rate: mL/h To regulate an IV volume by electronic infusion pump or controller calibrated in mL/h, calculate: (rounded to a whole number)

Calculation of IV Flow Rate: mL/h (continues) Order reads: D5W 250 mL IV over the next 2 h by infusion pump Step 1 Think. The pump is set by the rate of mL per hour. So, if 250 mL is to be infused in two hours, how much will be infused in one hour? 125 mL will be infused in one hour. You would set the pump at 125 mL per hour.

Calculation of IV Flow Rate: mL/h (continued) Step 2 Use the formula: Therefore, set the pump at 125 mL per hour (125 mL/h).

Calculation of IV Flow Rate: mL/h (continued) Step 2 Use the formula: Therefore, set the pump at 125 mL per hour (125 mL/h).

Calculation of IV Flow Rate: mL/h (continued) Step 2 Use the formula: Therefore, set the pump at 125 mL per hour (125 mL/h).

Calculation of mL/h: Infusion Rate is < 1 h (continued) Step 2 2 1

Calibration or drop factor (gtt/mL) IV Flow Rate: gtt/min The formula method to calculate IV flow rate for manually regulated IVs ordered in mL/h or for a prescribed number of minutes is: Calibration or drop factor (gtt/mL) Volume (mL) Time (min) gtt/min

IV Flow Rate: gtt/min Carry calculations to one decimal. Round gtt/min to the nearest whole number, because you can watch-count only whole drops.

Calculation of gtt/min The physician orders D5W IV @ 125 mL/h. The infusion set is calibrated for a drop factor of 10 gtt/mL. Calculate the IV flow rate in gtt/min. Notice that the mL cancel out, leaving gtt/min. 1 6 Use your watch to count the drops and adjust the roller clamp to deliver 21 gtt/min.

Calculation of gtt/min: Microdrip Drop Factor When the IV drop factor is 60 gtt/mL (microdrip sets), then the flow rate in gtt/min is the same as the volume ordered in mL/h.

Calculation of gtt/min: Microdrip Drop Factor Order: D5W NS IV @ 50 mL/h. The drop factor is 60 gtt/mL. Notice that the order, 50 mL/h, is the same as the flow rate of 50 gtt/min when the drop factor is 60 gtt/mL.

Drop Factor Constants Drop Factor Drop Factor Constant 10 gtt/mL

Adjusting IV Flow Rate (continued) Step 1 Step 2 Step 3 The % variation will be positive (+) if the administration is slow and the rate has to be increased, and negative () if the administration is too fast and the rate has to be decreased.

Calculation of IV Flow Rate Adjustment (continued) Adjusted flow rate 1 1

IV Push Rate Calculation Dosage Desired Quantity of Time Recommended IV Push Rate Time Supply Dosage Recommended

Calculation of IV Push Incremental Rate (continues) Order: Ativan 3 mg IV Push 20 min preoperatively Supply: Ativan 4 mg/mL with drug literature guidelines of “IV infusion not to exceed 2 mg/min.”

Calculation of IV Push Incremental Rate (continues) Order: Ativan 3 mg IV Push 20 min preoperatively Supply: Ativan 4 mg/mL with drug literature guidelines of “IV infusion not to exceed 2 mg/min.”

Calculation of IV Push Incremental Rate (continued) What is a safe infusion time? Use Formula Or, ratio-proportion

Calculation of IV Push Incremental Rate (continued) How much should you infuse every 15 seconds? 1 min = 60 sec; 1½ min = 1½ × 60 = 90 sec X = 0.125 mL = 0.13 mL of Ativan 4 mg/mL infused IV push every 15 seconds will deliver 3 mg of Ativan.

IV Fluid Volume To calculate total infusion volume; mL is known: To calculate IV volume; flow rate (gtt/min), drop factor, and time are known: Or, use ratio-proportion: “V” is the unknown

Standard Weight Based Heparin Protocol For all patients on heparin drips: 1. Weight in KILOGRAMS. Required for order to be processed: kg 2. Heparin 25,000 U in 250 mL of ½ NS. Boluses to be given as 1000 U/mL. 3. APTT q.6h or 6 hours after rate change; q.d. after two consecutive therapeutic APTTs. 4. CBC initially and repeat every day(s). 5. Obtain APTT and PT/INR on day one prior to initiation of therapy. 6. Guaiac stool initially then every day(s) until heparin discontinued. Notify if positive. 7. Neuro checks every hours while on heparin. Notify physician of any changes. 8. D/C APTT and CBC once heparin drip is discontinued, unless otherwise ordered. 9. Notify physician of any bleeding problems. 10. Bolus with 80 U/kg. Start drip at 18 U/kg/h. 11. If APTT is < 35 secs: Rebolus with 80 U/kg and increase rate by 4 U/kg/h 12. If APTT is 36–44 secs: Rebolus with 40 U/kg and increase rate by 2 U/kg/h 13. If APTT is 45–75 secs: Continue current rate 14. If APTT is 76–90 secs: Decrease rate by 2 U/kg/h 15. If APTT is > 90 secs: Hold heparin for 1 hour and decrease rate by 3 U/kg/h Heparin is an anticoagulant for the prevention of clot formation. It is measured in USP units. IV heparin is frequently ordered in units per hour and as should be administered by an electronic infusion device. Because of the potential for hemorrhage or clots with the incorrect dosage, careful monitoring of patients receiving heparin is a critical nursing skill. The nurse is responsible for administering the correct dosage and for ensuring that the dosage is safe. Heparin order, dosage, vial, and amount to give should be checked by another nurse before administering the dose.

Standard Weight Based Heparin Protocol Worksheet (continues) Round Patient’s Total Body Weight to Nearest 10 kg kg DO NOT Change the Weight Based on Daily Measurements FOUND ON THE ORDER FORM Initial Bolus (80 U/kg) U mL Initial Infusion Rate (18 U/kg/h) U/h mL/h Make adjustments to the heparin drip rate as directed by the order form. ALL DOSES ARE ROUNDED TO THE NEAREST 100 UNITS When IV heparin is ordered in U/h, use D/H X Q = R or ratio – proportion to calculate the flow rate in mL/h. Date Time APTT Bolus Rate Change U/h mL/h New Rate RN 1 RN 2

Standard Weight Based Heparin Protocol Worksheet (continued) If APTT is Then < 35 secs: Rebolus with 80 U/kg and increase rate by 4 U/kg/h 36–44 secs: Rebolus with 40 U/kg and increase rate by 2 U/kg/h 45–75 secs: Continue current rate 76–90 secs: Decrease rate by 2 U/kg/h > 90 secs: Hold heparin for one hour and decrease rate by 3 U/kg/h Because patients vary significantly in weight, the IV heparin dosage is individualized bsed on patient wt. Bolus or loading dosage and the initial infusion dosage of heparin are always based on patient’s wt. If the standard heparin bolus dosage is 80 U/kg and the infusion rate is 18 U/kg/h. The patient’s response to heparin therapy changes as measured by the PTT blood clotting value, the heparin dosage is adjusted as indicated. Signatures Initials

IV Heparin Protocol Bolus patient with heparin 80 U/kg body weight and start drip at 18 U/kg/h Patient’s weight 110 lb How many units of heparin should the patient receive? Step 1: Calculate pt.s wt. in kg ( 1kg=2.2 lb) Step 2: Calculate the heparin bolus dosage. 80 U/kg X 50 kg = 4000 U This pt should receive 4000 U IV hep. As a bolus

Calculate the number of milliliters to admin. For the bolus Supply: heparin 1000 U/mL Think: You want to give 4000 U, which is 4 times 1000 U/mL, so you want to give 4 times 1 mL or 4 mL. 4 D 4000 U H X Q = 1000 U X 1 mL = 4 mL Admin. 4 mL of heparin for the bolus

Calculate the infusion rate for the heparin IV drip Protocol: Start drip at 18 U/kg/h Supply: heparin 25,000 U/250 mL or 100 U/ml 18 U/kg/h X 50 kg = 900 u/h Think, you want to admin. 9 times 1 mL or 9mL for the heparin infusion 9 D 900 U/h H X Q 100 U X 1 mL/h = 9 mL/h 1

To calculate IV heparin flow rate in mL/h D (U/h desired) H (U have on hand) X Q (mL you have on hand)=R (mL/h) Or ratio or supply is equiv. to ratio of desired dosage rate Supply U Desired U/h Supply mL X mL/h

Order: D5W 500 mL w/ heparing 25,000 U IV at 1000 U/h D 1000 U/h H X Q = 25,000 U X 500 mL = R (mL/h 1000 U/h 1 20 25,000 U X 500 mL= 1000mL/h = 20 mL/h 50 50 1

Order: D5W 500 mL w/ hep 25,000 U IV at 850 U/h Calculate the flow rate in mL/h D 1 17 H X Q = 850 U/h X 500mL = 850 mL/h = 17 25,000 U 50 50 1

IV Flow Rate Ordered “Per Minute” To determine the flow rate (mL/h) for IV medications ordered per minute (such as mg/min): Step 1 Calculate the dosage in mL/min: Step 2 Calculate the flow rate of the quantity to administer in mL/h:

Ratio/Proportion 25,000 U = 850 U/h 500 mL X mL/h 25,000 X = 425,000 25,000 25,000 X = 17 mL/h

IV Flow Rate Ordered by “kg/min” To calculate flow rate (mL/h) for IV medications ordered by weight per minute (such as mg/kg/min): Step 1 Convert to like units, such as mg to mcg or lb to kg. Step 2 Calculate desired dosage per minute. Step 3 Calculate the desired dosage in mL/min. Step 4 Calculate the flow rate of the quantity to administer in mL/h.

Verifying Safe Drug Dosage Recommended “Per Minute” To check safe dosage of IV medications ordered in mL/h: Step 1 Calculate mg/h. Step 2 Calculate mg/min. Step 3 Compare recommended dosage and ordered dosage to decide if the dosage is safe.

Verifying Safe Drug Dosage Recommended by “kg/min” To check safe dosage of IV medications recommended in mg/kg/min and ordered in mL/h: Step 1 Convert to like units, such as mg to mcg or lb to kg. Step 2 Calculate recommended mg/min. Step 3 Calculate ordered mg/h. Step 4 Calculate ordered mg/min. Step 5 Compare ordered and recommended dosages; decide if safe.

IV and IV PB Flow Rates with Fluid Volume Restrictions (continues) Follow these six steps to calculate the flow rate of an IV, which includes IV PB. Calculate: Step 1 IV PB flow rate: or use

IV and IV PB Flow Rates with Fluid Volume Restrictions (continued) Step 2 Total IV PB time: Step 3 Total IV PB volume: Step 4 Total regular IV volume: Step 5 Total regular IV time: Time for one dose × # of doses in 24 h Volume of one dose × # of doses in 24 h Total volume – IV PB volume Total time – IV PB time

IV and IV PB Flow Rates with Fluid Volume Restrictions (continued) Step 6 Regular IV flow rate: or use

THE END