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Advanced Adult Intravenous Calculations

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Advanced Adult Intravenous Calculations

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.

- Step 1

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

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

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

Standard Weight Based Heparin Protocol Worksheet (continues)

Standard Weight Based Heparin Protocol Worksheet

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

Standard Weight Based Heparin Protocol Worksheet (continued)

- 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

- 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

- 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

- 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

- 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

- 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:

- 25,000 U = 850 U/h
- 500 mL X mL/h
- 25,000 X = 425,000
- 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