Calculate with ConfidenceCalculate with Confidence55thth edition edition

Gray MorrisGray Morris

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Additional Conversions Useful Additional Conversions Useful in the Health Care Settingin the Health Care Setting

Unit Two: Chapter 9Unit Two: Chapter 9

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Additional Useful Conversions: Additional Useful Conversions: ObjectivesObjectives

After reviewing this chapter, you should be After reviewing this chapter, you should be

able to:able to:

1.1. Convert between Celsius and Fahrenheit Convert between Celsius and Fahrenheit temperaturestemperatures

2.2. Convert between units of length: inches, Convert between units of length: inches, centimeter, and millimeterscentimeter, and millimeters

3.3. Convert between units of weight: pounds Convert between units of weight: pounds and kilograms, pounds and ounces to and kilograms, pounds and ounces to kilogramskilograms

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Converting Between Converting Between Celsius and FahrenheitCelsius and Fahrenheit

Temperature reading followed by Temperature reading followed by FF = = Fahrenheit (e.g., 98° F)Fahrenheit (e.g., 98° F)

Followed by Followed by CC = Celsius (formerly centigrade) = Celsius (formerly centigrade) (e.g., 36° C)(e.g., 36° C)

Freezing point of HFreezing point of H22O is 32° F and 0° CO is 32° F and 0° C

Boiling point of HBoiling point of H22O is 212° F and 100° CO is 212° F and 100° C

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Figure 9-1 Celsius and Fahrenheit temperature scales.Figure 9-1 Celsius and Fahrenheit temperature scales.(From Clayton BD, Stock YN: (From Clayton BD, Stock YN: Basic pharmacology forBasic pharmacology for nurses, nurses, ed. 14, St.ed. 14, St.

Louis, 2007, Mosby.) Louis, 2007, Mosby.) Note: Note: Glass thermometers pictured here are forGlass thermometers pictured here are fordemonstration purposes only. Electronic digital temperature devices aredemonstration purposes only. Electronic digital temperature devices are

more commonly used in health care settings.more commonly used in health care settings.

Figure 9-2 Ranges of normal temperature values and physiologicalFigure 9-2 Ranges of normal temperature values and physiologicalconsequences of abnormal body temperature. (From Potter PA,consequences of abnormal body temperature. (From Potter PA,Perry AG: Perry AG: Fundamentals of nursing, Fundamentals of nursing, ed. 7, St. Louis, 2009, Mosby.) ed. 7, St. Louis, 2009, Mosby.)

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Temperature Conversion Temperature Conversion FormulasFormulas

To convert from Celsius to Fahrenheit, To convert from Celsius to Fahrenheit, multiply by 1.8 or and add 32multiply by 1.8 or and add 32

Example: Convert 37.5° C to °FExample: Convert 37.5° C to °F

°F = 1.8(°C) + 32 °F = 1.8(°C) + 32 oror °F = 9/5(°C) + 32 °F = 9/5(°C) + 32

°F = (1.8) °F = (1.8) ×× 37.5 + 32 37.5 + 32

°F = 67.5 + 32°F = 67.5 + 32

°F = 99.5°°F = 99.5°

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Temperature Conversion Temperature Conversion FormulasFormulas (cont’d)(cont’d)

To convert from Fahrenheit to Celsius, To convert from Fahrenheit to Celsius, subtract 32 and divide by 1.8 orsubtract 32 and divide by 1.8 or

Example: Convert 68° F to °C Example: Convert 68° F to °C

Formula: °C = (°F - 32) Formula: °C = (°F - 32) 9/5 9/5

°C = (68 - 32) °C = (68 - 32) 9/5 9/5

°C = 36 °C = 36 9/5, which inverts to be °C = 36 9/5, which inverts to be °C = 36 ×× 5/9 5/9

°C = 180/9°C = 180/9

°C = 20°°C = 20°

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Conversions: Metrics and LengthConversions: Metrics and Length

Metric measures are used forMetric measures are used for Pupil sizePupil size Baby’s head circumferenceBaby’s head circumference Wounds and incisions Wounds and incisions

(length (length width width depth in cm or mm) depth in cm or mm) Conversion factor: 1 cm = 10 mmConversion factor: 1 cm = 10 mm If incision is 25 cm, how many mm is it?If incision is 25 cm, how many mm is it?

25 mm = 25 25 mm = 25 10 = 2.5 cm or 25 = 2.5 cm 10 = 2.5 cm or 25 = 2.5 cm

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Conversions: Metrics and Length Conversions: Metrics and Length (cont’d)(cont’d)

Convert 30 cm to inches (in)Convert 30 cm to inches (in) Conversion factor: 1 in = 2.5 cmConversion factor: 1 in = 2.5 cm Think smaller to larger (divide)Think smaller to larger (divide)

30 30 2.5 = 12 in 2.5 = 12 in

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Conversions Relating to WeightConversions Relating to Weight

Body weight is important in calculating doses Body weight is important in calculating doses for certain medicationsfor certain medications

Delivered in mg or mcg per kilogramDelivered in mg or mcg per kilogram Nurse needs to calculate safety of doses Nurse needs to calculate safety of doses

documented as mg/kgdocumented as mg/kg May need to convert pounds and ounces in May need to convert pounds and ounces in

pediatric calculationspediatric calculations

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Conversions Relating to Weight Conversions Relating to Weight (cont’d)(cont’d)

Pounds to KilogramsPounds to Kilograms Conversion factor: 2.2 lb = 1 kgConversion factor: 2.2 lb = 1 kg Smaller to larger (divide lb value by 2.2)Smaller to larger (divide lb value by 2.2) Round answers to nearest tenthRound answers to nearest tenth

Example: Convert 65 lb to kilogramsExample: Convert 65 lb to kilograms

kg = 65 kg = 65 2.2 = 29.54 2.2 = 29.54 rounds torounds to 29.5 kg29.5 kg

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Conversions Relating to Weight Conversions Relating to Weight (cont)(cont)

Pounds Pounds and and ounces to kilogramsounces to kilograms Convert oz to nearest tenth of lb and add Convert oz to nearest tenth of lb and add

to poundsto pounds Equivalent: 16 oz = 1 lbEquivalent: 16 oz = 1 lb Convert total lb to kg, then round to Convert total lb to kg, then round to

nearest tenthnearest tenth

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Conversions Relating to Weight Conversions Relating to Weight (cont’d)(cont’d)

Pounds and ounces to kilograms (cont’d)Pounds and ounces to kilograms (cont’d) A child weighs 10 lb 2 ozA child weighs 10 lb 2 oz Think smaller to largerThink smaller to larger

2 oz 2 oz 16 = 0.12 16 = 0.12 rounds torounds to 0.1 lb 0.1 lb

10 lb + 0.1 lb = 10.1 lb10 lb + 0.1 lb = 10.1 lb Think smaller to largerThink smaller to larger

10.1 10.1 2.2 = 4.59 2.2 = 4.59 rounds torounds to 4.6 kg 4.6 kg

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Conversions Relating to Weight Conversions Relating to Weight (cont’d)(cont’d)

Kilograms to PoundsKilograms to Pounds Multiply by 2.2 (think larger to smaller)Multiply by 2.2 (think larger to smaller) Equivalent: 1 kg = 2.2 lbEquivalent: 1 kg = 2.2 lb A child weighs 24.7 kg; convert to poundsA child weighs 24.7 kg; convert to pounds

lb = 24.7 lb = 24.7 2.2 = 54.34 2.2 = 54.34 rounds torounds to 54.3 lb 54.3 lb(weight in kg) (weight in kg) (equivalent) (equivalent)

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Military TimeMilitary Time

International timeInternational time Uses a 24-hour clockUses a 24-hour clock Helps prevent errors by eliminating repetition Helps prevent errors by eliminating repetition

of numbersof numbers No colon (:) or a.m./p.m. designationsNo colon (:) or a.m./p.m. designations Midnight = 0000 and 2400Midnight = 0000 and 2400 1:00 a.m. = 01001:00 a.m. = 0100 Now referred to as “Computer Time”Now referred to as “Computer Time”

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Figure 9-3  Clocks showing traditional and military time.Figure 9-3  Clocks showing traditional and military time.

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Time: Traditional to ComputerTime: Traditional to Computer

To convert a.m. time, omit the colon and To convert a.m. time, omit the colon and “a.m.,” then add a zero to the beginning to “a.m.,” then add a zero to the beginning to make a four-digit numbermake a four-digit number Example: 8:45 a.m. = 0845Example: 8:45 a.m. = 0845

To convert p.m. time, omit the colon and To convert p.m. time, omit the colon and “p.m.,” then add 1200 to the time“p.m.,” then add 1200 to the time Example: 7:50 pm = 1950Example: 7:50 pm = 1950

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Time: Computer to TraditionalTime: Computer to Traditional

To convert times between 0000 and 1200, To convert times between 0000 and 1200, delete any zero at the beginning, insert colon, delete any zero at the beginning, insert colon, and add “a.m.”and add “a.m.” Example: 0845 = 8:45 a.m.Example: 0845 = 8:45 a.m.

To convert times between 1200 and 2400, To convert times between 1200 and 2400, subtract 1200, insert colon, and add “p.m.”subtract 1200, insert colon, and add “p.m.” Example: 1950 = 7:50 p.m.Example: 1950 = 7:50 p.m.