Introduction

Whether in the hospital setting or in the community pharmacy, time, temperature, and the ability to read numbering systems are essential so the correct amount of medication will be given at the correct time and at the correct temperature if that is essential. A pharmacy technician will use both Arabic numerals, such as 1, 2, 3, and so on, and Roman numerals, such as I, V, X, and so on, when interpreting physicians’ orders. As citizens of the Western Hemisphere, we are familiar with Arabic numbers, which are used daily, and numbers that are related to the English system of measurement. These numbers are used for steps in our daily lives from writing a check to looking at a page number in a book. Numbers in the preface of a book, however, are usually written in Roman numerals.

Most of you probably have not used Roman numerals for many years, but these numerical symbols will be used daily in the medical field. In the same manner, in our daily world we use the standard clock whereas in patient settings we often use military time to prevent misinterpretation of the medicinal order. Finally, temperature is read and recorded in Fahrenheit in our daily lives, using 32° as the freezing point of water and 212° as boiling, such as 95° F outside on a hot day. The Celsius thermometer, where water freezes at 0° and boils at 100°, is used in some medical settings that prefer metric measurements. The Celsius thermometer is used in many clinical teaching locations, with the normal body temperature being 37° instead of the 98.6° found in the Fahrenheit scale. When the patient information is used internationally for study, the Celsius or centigrade scale is often used.

Arabic Numbers And Roman Numerals

Medication orders or prescriptions are written in both Arabic and Roman numerals, depending on the amount of medication ordered or the prescriber’s preference. Arabic numerals are those most common such as 2 for whole numbers, as fractional numbers, or 0.53 as a decimal number.

Roman numerals, which date back to the ancient Roman Empire, use letters to represent numerical amounts. The following are the numbers depicted by Roman numerals.

Conversion Between 12-Hour And Universal (Military Or 24-Hour) Time

Because traditional time can be misinterpreted when using am and pm with the same numbers to indicate the time of day for medication administration, many hospitals and other health care facilities use 24-hour, or military, time, also called universal time. This time will reduce the chance of errors when time is a necessary indicator in medication administration. The differentiation of time is not dependent on just the initials am or pm but is expressed as different numbers of time from 0001 to 2400.

In universal time, all time is expressed in four-digit numbers beginning at 1 minute past midnight, or 0001 hours. The time is stated in hundreds of hours with 1 am being 0100 hours and said as “zero one-hundred hours.” Ten in the morning is the first time that a double digit precedes the hour with 10 o’clock being said as “ten hundred hours.” Noon is 1200 hours and said as “twelve hundred hours.” One o’clock in the afternoon becomes 1300 hours, or “thirteen hundred hours.” Midnight then becomes 2400, or “twenty-four hundred hours,” or at some sites it is read as 0000, or “zero hundred hours.” Figure 3-1 shows an example of a military time clock. The am (ante meridian, or before noon) readings are found on the inside of the clock face, whereas the pm (post meridian, or after noon) readings are found on the outside of the clock face.

Minutes in military time are written as the last two digits in the time line (e.g., 2:59 am would be expressed as 0259). The minutes are just converted to the last digits in the time behind the hour of time. If the time is 4:46 pm, it would be read as “sixteen forty-six hours,” or 1646 hours.

Conversion Between Fahrenheit And Celsius Temperature

In the United States, Fahrenheit temperature (F) is the measurement most commonly used. In countries where the metric system is used, Celsius (C) or centigrade temperature measurement is the most commonly used scale. In the Fahrenheit scale, water boils at 212°, whereas in Celsius water boils at 100°. Likewise, the freezing points are not the same; Fahrenheit is 32°, whereas Celsius is 0°. Figure 3-2 provides a comparison of the scales. As you can quickly see, the Fahrenheit scale has 180° between the freezing and boiling points, whereas the Celsius scale contains only 100°. The formulas for conversion between the two scales have been developed with these differences as the basis. The conversion equations are shown below.

If the differences in Fahrenheit to Celsius could be placed into a fractional unit, the fraction for changing to the Celsius scale would be that for each Celsius degree in temperature, the Fahrenheit difference would be . Another way of looking at it is that the Celsius degree is 1.8 Fahrenheit degrees after the difference of 32° has been subtracted from the Fahrenheit temperature. If we want the number of Celsius degrees in the Fahrenheit scale, the Celsius scale would be that , or of the Celsius degree is found in one Fahrenheit degree. So the following conversion formulas may be used to change from one temperature scale to the other.

Converting Fahrenheit Temperature to Celsius Temperature

Two methods are available to convert a temperature in Fahrenheit to the equivalent Celsius temperature:

< ?xml:namespace prefix = "mml" />(A) C°=F°−321.8or(B) C°=(F°−32)×59

In the first method (A), subtract 32 from the Fahrenheit temperature and divide by 1.8. In the second method (B), subtract 32 from the Fahrenheit temperature and multiply that answer by 5. Then divide by 9. In either case, the remainder should be rounded to tenths as appropriate.

Example 3-4

Convert 96.5° F to C°.

(A) C°=96.5−32 (64.5)÷1.8=35.833 or 35.8°

OR

(B) C°=96.5−32 (64.5)×5 (322.5)÷9=35.8333 or 35.8°

Converting Celsius Temperature to Fahrenheit Temperature

To convert Celsius temperature to Fahrenheit temperature, you can also use two methods:

(A) F°=1.8 C°+32 (1.8×C°+32)or(B) F°=9×C°5+32

In the first method (A), multiply the Celsius temperature by 1.8 and add 32. In the second method (B), multiply the Celsius temperature by 9 and divide that answer by 5. Then add 32 to the answer.

Example 3-5

Convert 65° C to F° using F° = 1.8° C + 32.

F°=65°×1.8 (117)+32=149°F

OR

Using F° = + 32, the formula would look like the following:

F°=585 (9×65°)÷5+32=117+32=149° F

Alternate Formula for Converting between Celsius and Fahrenheit

This formula may be used for conversions for both systems:

9C°=5F°−160

Example 3-6

Convert 65° C to F°.

Hint: When crossing the equal sign, the mathematical signs are reversed and those numbers subtracted on one side become added on the other, as shown here:

9×65=5F−160

5F=9×65+160

5° F=585+160 or 745

F°=745÷5

F°=149°

Example 3-7

Convert 96.5° F to C°.

9 C=96.5×5−160

9 C=482.5−160

9 C=322.5

C°=322.5÷9

C°=35.8°

Learn the formula that is easiest for you. Notice that the answers obtained using this formula are identical to those using the formulas earlier.

 Tech Alert

If an electronic thermometer is used in the clinical area, most of these devices automatically convert between Celsius and Fahrenheit. The machine may have to be manually changed between the different scales. Each thermometer would have directions from the manufacturer to accomplish the change.

Practice Problems D

Convert the following temperatures using the appropriate formulas. Round to tenths as appropriate.

1. 1° F = __________ C

2. 35° C = __________ F

3. 35° F = __________ C

4. 19° C = __________ F

5. 112° F = __________ C

6. 34° C = __________ F

7. 36.5° C = __________ F

8. 102.6° F = __________ C

9. 98.6° F = __________ C

10. 99.2° F = __________ C

11. 37.2° C = __________ F

12. 100.2° F = __________ C

13. 10.2° C = __________ F

14. 130.6° F = __________ C

15. 48.2° C = __________ F

16. If a serum is to be stored at a temperature cooler than 40° F, what is the temperature for storage in a refrigerator on a Celsius thermometer? __________

17. Mrs. Jones is to receive an antibiotic if her temperature is above 103.8° F. What is the Celsius conversion? __________

18. A parenteral medication is to arrive through the mail. The label on the box states that the medication cannot be exposed to temperatures higher than 47.8° C. The current outdoor temperature is 100.2° F. Can the medication be safely used? __________ What is the converted temperature? __________

19. If a bottle of medication must be stored at a temperature cooler than 45° F, what is the Celsius temperature at which the medication must be stored? __________

20. A bag of fluids must be given at body temperature of 98.6° F. What is that temperature in the Celsius measurement? __________

Posttest

Before taking the Posttest, retake the Pretest to check your understanding of the materials presented in this chapter.

Complete the mathematical calculations as needed. Always show your work so that you can verify the results.

Change the following to either Arabic numbers or Roman numerals as appropriate.

1.  __________

2. xliv __________

3.  __________

4. ccl __________

5. 45 __________

6. __________

7. 46 __________

8. 59 __________

9. 75 __________

10.  __________

11. lxviii __________

12. cxxv __________

13. xii __________

14. 78 __________

15. 165 __________

Change the following to either 24-hour time or 12-hour time as appropriate.

16. 0530 __________

17. 8:30 am __________

18. 1625 __________

19. 2:30 pm __________

20. 1325 __________

21. 0045 __________

22. 12:05 am __________

23. 9:30 pm __________

24. 12:10 pm __________

25. 0010 __________

26. 1755 __________

27. 3:26 pm __________

28. 1455 __________

29. 5:30 pm __________

30. 0635 __________

Convert the following temperatures. If Fahrenheit is listed, change to Celsius; if Celsius is given, change to Fahrenheit. Round to tenths.

31. 124° F __________

32. 49.2° F __________

33. 36.5° C __________

34. 234° F __________

35. 12.4° C __________

36. 99.6° F __________

37. 38.6° C __________

38. 86° F __________

39. 180° F __________

40. 94.2° F __________

41. 103° F __________

42. 100° C __________

43. 32° F __________

44. 2° F __________

45. 2° C __________

Answer the following questions in mathematical terms.

46. The room temperature in the pharmacy is 68° F. What is the temperature in Celsius? __________

47. A medication cannot be frozen. The refrigerator is set for 5° C. What is the temperature in Fahrenheit? __________ Will the medication freeze? __________

48. A patient has a temperature of 38.6° C. What is the temperature in Fahrenheit? __________ Should the medical professional be concerned about this body temperature? __________

49. A refrigerator in the pharmacy department shows a temperature of 35.2° C. Should the pharmacy technician be concerned about any medications that must be stored below 50° F? __________ What is the temperature in Fahrenheit? __________

50. A physician writes an order for xxiv tablets. How many tablets should be dispensed? __________

51. An order shows to dispense xc number of tablets. How many tablets will be dispensed? __________

52. When writing a prescription, the physician wants grains to be dispensed as a tablet dose. How many grains of medication will be given as the dose? __________

53. An order states to give medications at 0800, 1200, and 2000. What times are the medications to be given in 12-hour time? __________ __________ __________

54. A physician wants medication to be given every 6 hours beginning at 6:00 am. Write the universal time for every 6 hours. __________ __________ __________ __________

55. A chart reads that the patient had pain medication at 5:35 pm. The medication can be taken every 6 hours. At what time in universal time could the next dose of medicine be given? __________

56. A medication order is to dispense xlviii tablets. How many tablets is this in Arabic numbers? __________

57. You supply a medication to the floor at 4:30 pm. You must chart the supply in universal time. What is the time of delivery? __________

58. The temperature in a patient’s room is 37.6° C. What is the temperature in Fahrenheit? __________

59. If a medication is to be stored below 45° F, what would be the temperature on a Celsius thermometer in a refrigerator? __________

60. If a medication must be frozen at all times and the label states that it should be stored below 27° F, what would you need the refrigerator temperature to be in Celsius? __________