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Practice problems · Pump rates · 5 worked

mL per hr IV rate practice problems

An mL per hr problem asks what rate to set on an infusion pump. Sometimes it is a volume over a time, such as 1,000 mL over 10 hours. Sometimes it is a dose rate, such as 20 mcg/min, carried through the bag's concentration and turned from minutes into hours.

The rounding rule on this page

Every answer here is rounded once, at the end, under one stated rule: nearest tenth, half rounds up, except tablets and capsules, rates in milliliters per hour and drip rates in drops per minute, which go to the nearest whole number, half rounds up. Your program's rule may differ, and on an exam it is the one that counts.

Work each problem on paper first, then open its solution. Each one is one of the 20 problems in DoseReady's mL per hr family, with the numbers the app drew for it.

No licensed clinician has reviewed the problem set. Where a problem and its source disagree, trust the source and what your program teaches.

Problem 1 of 5

A bag of normal saline holding 1,000 mL is ordered to infuse over 10 hr. At what rate is the pump set, in milliliters per hour?

Show the worked solution

Dimensional analysis

1,000 × 1 ÷ 10 = 100

Ratio and proportion

DoseReady does not yet set this problem out as a textbook proportion, with like units in the same places, so it is not shown here. The chain above is the working.

Formula method

DoseReady sets this problem out in the formula method with the dose desired and the dose on hand in different units, which is not the method's textbook form, so it is not shown here. The chain above is the working.

The working comes to
100 mL/hr
The answer under the stated rule
100 mL/hr
Nearest whole number, half rounds up, the stated rule for rates in milliliters per hour.

What each slip gives here

  • Decimal point one place out1,000 mL/hr or 10 mL/hr
  • Conversion factor inverted10,000 mL/hr

What this problem is built from

Problem 2 of 5

A rehydration infusion of half-normal saline totaling 1,000 mL is ordered to run over 5 hr. At what rate is the pump set, in milliliters per hour?

Show the worked solution

Dimensional analysis

1,000 × 1 ÷ 5 = 200

Ratio and proportion

DoseReady does not yet set this problem out as a textbook proportion, with like units in the same places, so it is not shown here. The chain above is the working.

Formula method

DoseReady sets this problem out in the formula method with the dose desired and the dose on hand in different units, which is not the method's textbook form, so it is not shown here. The chain above is the working.

The working comes to
200 mL/hr
The answer under the stated rule
200 mL/hr
Nearest whole number, half rounds up, the stated rule for rates in milliliters per hour.

What each slip gives here

  • Decimal point one place out2,000 mL/hr or 20 mL/hr
  • Conversion factor inverted5,000 mL/hr
  • Conversion skipped1,000 mL/hr

What this problem is built from

Problem 3 of 5

A cefazolin piggyback is mixed in 100 mL of solution and is to infuse over 20 min. At what rate is the pump set, in milliliters per hour?

Show the worked solution

Dimensional analysis

100 × 1 × 60 ÷ 20 ÷ 1 = 300

Ratio and proportion

DoseReady does not yet set this problem out as a textbook proportion, with like units in the same places, so it is not shown here. The chain above is the working.

Formula method

The formula method (D ÷ H × Q) does not fit this problem. The chain above is the working.

The working comes to
300 mL/hr
The answer under the stated rule
300 mL/hr
Nearest whole number, half rounds up, the stated rule for rates in milliliters per hour.

What each slip gives here

  • Decimal point one place out3,000 mL/hr or 30 mL/hr
  • Conversion factor inverted120,000 mL/hr
  • Conversion skipped6,000 mL/hr or 5 mL/hr

What this problem is built from

Problem 4 of 5

A nitroglycerin infusion is supplied at a concentration of 200 mcg per milliliter. The order is 20 mcg/min. At what rate is the pump set, in milliliters per hour?

Show the worked solution

Dimensional analysis

20 × 1 × 60 ÷ 200 ÷ 1 = 6

Ratio and proportion

DoseReady does not yet set this problem out as a textbook proportion, with like units in the same places, so it is not shown here. The chain above is the working.

Formula method

The formula method (D ÷ H × Q) does not fit this problem. The chain above is the working.

The working comes to
6 mL/hr
The answer under the stated rule
6 mL/hr
Nearest whole number, half rounds up, the stated rule for rates in milliliters per hour.

What each slip gives here

  • Decimal point one place out60 mL/hr or 1 mL/hr
  • Conversion factor inverted240,000 mL/hr
  • Conversion skipped1,200 mL/hr

What this problem is built from

Problem 5 of 5

After surgery, an infusion of lactated Ringer solution totaling 1,000 mL is to run over 10 hr. At what rate is the pump set, in milliliters per hour?

Show the worked solution

Dimensional analysis

1,000 × 1 ÷ 10 = 100

Ratio and proportion

DoseReady does not yet set this problem out as a textbook proportion, with like units in the same places, so it is not shown here. The chain above is the working.

Formula method

DoseReady sets this problem out in the formula method with the dose desired and the dose on hand in different units, which is not the method's textbook form, so it is not shown here. The chain above is the working.

The working comes to
100 mL/hr
The answer under the stated rule
100 mL/hr
Nearest whole number, half rounds up, the stated rule for rates in milliliters per hour.

What each slip gives here

  • Decimal point one place out1,000 mL/hr or 10 mL/hr
  • Conversion factor inverted10,000 mL/hr

What this problem is built from

Practice under your own program's rules

In DoseReady you enter your program's passing score, notation and rounding rule once. Every answer is graded under that rounding rule, and each worked solution is written in your notation where the problem allows it.

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