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Nursing Math & Dosage Foundations · 500-Question Practice Bank (worked answers)

Parenteral Dosages and Syringes — practice set (Q101–160)

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60 dosage-calculation problems (questions 101–160) with a full worked answer for each: dimensional-analysis setup, raw calculation, rounding rule, final labeled answer, rationale and clinical pearl. Work each one on paper first, then open the answer.

Check yourself

60 review questions from the chapter. Try each one, then open the answer.

  1. Question 101. Scenario: A nurse in an outpatient clinic must administer a small-volume intramuscular injection to an adult patient. Order: Administer 0.4 mL intramuscularly. Available: Tuberculin (1-mL) syringe calibrated in 0.01 mL; 3-mL syringe calibrated in 0.1 mL; 5-mL syringe calibrated in 0.2 mL. Question: Which syringe provides the most accurate measurement for this dose? No rounding needed.

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    Correct answer: Tuberculin (1-mL) syringe Setup (dimensional analysis): No calculation required (syringe selection). Raw calculation: N/A Rounding: N/A Final answer: Tuberculin (1-mL) syringe Rationale: The dose is 0.4 mL, which is under 1 mL. A tuberculin syringe is calibrated in 0.01-mL increments, allowing the 0.4-mL dose to be measured far more precisely than on a 3-mL syringe (0.1-mL increments) or a 5-mL syringe (0.2-mL increments). Clinical pearl: For volumes less than 1 mL that require precision, select the smallest syringe that will hold the dose.

  2. Question 102. Scenario: A nurse is preparing an intramuscular injection for an adult patient in the emergency department. Order: Administer 2.5 mL intramuscularly. Available: Tuberculin (1-mL) syringe; 3-mL syringe; 5-mL syringe. Question: Which syringe should the nurse select? No rounding needed.

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    Correct answer: 3-mL syringe Setup (dimensional analysis): No calculation required (syringe selection). Raw calculation: N/A Rounding: N/A Final answer: 3-mL syringe Rationale: 2.5 mL exceeds the 1-mL capacity of a tuberculin syringe, so it must be measured in a larger syringe. A 3-mL syringe (0.1-mL increments) holds the dose and measures it more accurately than a 5-mL syringe. Clinical pearl: Select the smallest syringe that accommodates the entire dose; do not use a tuberculin syringe for volumes greater than 1 mL.

  3. Question 103. Scenario: A patient with type 1 diabetes mellitus is due for a mealtime insulin dose. Order: Administer regular insulin U-100 30 units subcutaneously. Available: U-100 insulin syringes calibrated in units (0.3-mL/30-unit, 0.5-mL/50-unit, and 1-mL/100-unit). Question: How many units should be drawn up, and which syringe size is appropriate? No rounding needed.

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    Correct answer: 30 units; 0.5-mL (50-unit) or 1-mL (100-unit) U-100 insulin syringe Setup (dimensional analysis): Insulin is measured in units on a U-100 syringe; 1 mL = 100 units. Raw calculation: 30 units (no conversion needed). Rounding: N/A (whole units) Final answer: 30 units Rationale: U-100 insulin is ordered and measured in units using an insulin syringe. Thirty units fills a 0.3-mL (30-unit) syringe exactly to capacity, leaving no room to spare; a 0.5-mL (50-unit) or 1-mL (100-unit) syringe is typically selected for easier, more accurate reading. Clinical pearl: Always use an insulin syringe calibrated in units for insulin; never substitute a tuberculin or 3-mL syringe for insulin doses measured in units.

  4. Question 104. Scenario: A provider writes an insulin order in milliliters, and the nurse must convert it to insulin units for an insulin syringe. Order: Administer 0.25 mL of U-100 insulin subcutaneously. Available: U-100 insulin (100 units per mL). Question: How many units does this order represent? Round to a whole unit if needed.

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    Correct answer: 25 units Setup (dimensional analysis): 0.25 mL × (100 units / 1 mL) = 25 units Raw calculation: 0.25 × 100 = 25 Rounding: Already a whole unit; no rounding needed. Final answer: 25 units Rationale: U-100 insulin contains 100 units per mL, so 0.25 mL contains 25 units. The mL units cancel, leaving units. Clinical pearl: To convert a U-100 insulin volume (mL) to units, multiply by 100 units/mL.

  5. Question 105. Scenario: An adult patient requires an intramuscular injection for pain. Order: Administer 50 mg intramuscularly. Available: Vial labeled 100 mg per mL. Question: How many milliliters should the nurse draw up? Round to the nearest tenth if needed.

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    Correct answer: 0.5 mL Setup (dimensional analysis): 50 mg × (1 mL / 100 mg) = 0.5 mL Raw calculation: 50 ÷ 100 = 0.5 Rounding: Already to the tenth; no further rounding needed. Final answer: 0.5 mL Rationale: The mg units cancel, leaving mL. A 3-mL syringe measures 0.5 mL accurately. Clinical pearl: When concentration is 100 mg/mL, each 0.1 mL delivers 10 mg; a 50-mg dose is therefore 0.5 mL.

  6. Question 106. Scenario: A postoperative patient requires prophylactic anticoagulation. Order: Administer heparin 5,000 units subcutaneously. Available: Vial labeled heparin 10,000 units per mL. Question: How many milliliters should the nurse administer? Round to the nearest tenth if needed.

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    Correct answer: 0.5 mL Setup (dimensional analysis): 5,000 units × (1 mL / 10,000 units) = 0.5 mL Raw calculation: 5,000 ÷ 10,000 = 0.5 Rounding: Already to the tenth; no further rounding needed. Final answer: 0.5 mL Rationale: The units cancel, leaving mL. Half a milliliter of a 10,000 units/mL solution delivers 5,000 units. Clinical pearl: Subcutaneous heparin volumes are small; verify the syringe and concentration carefully because heparin vials come in multiple strengths.

  7. Question 107. Scenario: A clinic nurse is placing a tuberculin skin test on a new employee. Order: Administer 0.1 mL intradermally. Available: Tuberculin (1-mL) syringe; 3-mL syringe; insulin U-100 syringe. Question: Which syringe should the nurse select for this intradermal injection? No rounding needed.

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    Correct answer: Tuberculin (1-mL) syringe Setup (dimensional analysis): No calculation required (syringe selection). Raw calculation: N/A Rounding: N/A Final answer: Tuberculin (1-mL) syringe Rationale: Intradermal doses (such as a 0.1-mL tuberculin skin test) are tiny and must be measured with a tuberculin syringe calibrated in 0.01-mL increments for accuracy. Clinical pearl: Intradermal injections are almost always 0.1 mL or less and require a tuberculin syringe for accurate, shallow delivery.

  8. Question 108. Scenario: A nurse is drawing up a medication and checking the volume in a 3-mL syringe calibrated in 0.1-mL increments. Order: The intended dose corresponds to the plunger's top ring resting exactly on the 1.8-mL calibration line. Available: 3-mL syringe (0.1-mL increments). Question: What volume (in mL) is indicated? No rounding needed.

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    Correct answer: 1.8 mL Setup (dimensional analysis): Direct reading of syringe graduation. Raw calculation: N/A Rounding: N/A Final answer: 1.8 mL Rationale: A 3-mL syringe calibrated in 0.1-mL increments has a line at 1.8 mL; the top ring of the plunger resting on that line indicates 1.8 mL. Clinical pearl: Read the plunger at its top flat ring (nearest the needle), not the tip of the rubber stopper.

  9. Question 109. Scenario: A nurse verifies a small dose in a tuberculin (1-mL) syringe calibrated in 0.01-mL increments. Order: The plunger's top ring rests on the line three small graduations above 0.32 mL. Available: Tuberculin (1-mL) syringe (0.01-mL increments). Question: What volume (in mL) is indicated? No rounding needed.

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    Correct answer: 0.35 mL Setup (dimensional analysis): 0.32 mL + (3 × 0.01 mL) = 0.35 mL Raw calculation: 0.32 + 0.03 = 0.35 Rounding: N/A Final answer: 0.35 mL Rationale: On a tuberculin syringe each small graduation is 0.01 mL. Three graduations above 0.32 mL is 0.35 mL. Clinical pearl: Count the number of small lines beyond a labeled value and multiply by the calibration increment.

  10. Question 110. Scenario: A nurse verifies an insulin dose in a U-100 insulin syringe. Order: The plunger's top ring rests on the 16-unit calibration mark. Available: U-100 insulin syringe calibrated in 1-unit increments. Question: How many units are indicated? No rounding needed.

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    Correct answer: 16 units Setup (dimensional analysis): Direct reading of insulin syringe unit markings. Raw calculation: N/A Rounding: N/A Final answer: 16 units Rationale: A U-100 insulin syringe is calibrated in units, so the plunger resting on the 16-unit mark indicates 16 units. Clinical pearl: Insulin syringes read directly in units; do not convert units to mL when using a U-100 syringe.

  11. Question 111. Scenario: An adult patient needs an intramuscular antibiotic. Order: Administer 0.75 g intramuscularly. Available: Vial labeled 1 g per 2 mL. Question: How many milliliters should the nurse administer? Round to the nearest tenth if needed.

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    Correct answer: 1.5 mL Setup (dimensional analysis): 0.75 g × (1,000 mg / 1 g) × (2 mL / 1,000 mg) = 1.5 mL Raw calculation: 750 mg × (2 mL / 1,000 mg) = 1.5 mL Rounding: Already to the tenth; no further rounding needed. Final answer: 1.5 mL Rationale: Convert grams to milligrams (0.75 g = 750 mg), then use the concentration 1 g (1,000 mg) per 2 mL. The mg and g units cancel, leaving mL. Clinical pearl: When a vial lists concentration per gram, convert to milligrams first to keep the units consistent.

  12. Question 112. Scenario: A nurse prepares an intramuscular antiemetic. Order: Administer 10 mg intramuscularly. Available: Vial labeled 5 mg per mL. Question: How many milliliters should the nurse draw up? Round to the nearest tenth if needed.

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    Correct answer: 2 mL Setup (dimensional analysis): 10 mg × (1 mL / 5 mg) = 2 mL Raw calculation: 10 ÷ 5 = 2 Rounding: Whole number; no rounding needed. Final answer: 2 mL Rationale: The mg units cancel, leaving mL. Two mL of a 5 mg/mL solution delivers 10 mg. Clinical pearl: With a 5 mg/mL concentration, each 1 mL provides 5 mg, so 10 mg requires 2 mL.

  13. Question 113. Scenario: A patient is prescribed a subcutaneous low-molecular-weight heparin for deep vein thrombosis prophylaxis. Order: Administer enoxaparin 40 mg subcutaneously. Available: Prefilled syringe labeled 100 mg per mL. Question: How many milliliters should the nurse administer? Round to the nearest tenth if needed.

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    Correct answer: 0.4 mL Setup (dimensional analysis): 40 mg × (1 mL / 100 mg) = 0.4 mL Raw calculation: 40 ÷ 100 = 0.4 Rounding: Already to the tenth; no further rounding needed. Final answer: 0.4 mL Rationale: The mg units cancel, leaving mL. A prefilled enoxaparin syringe at 100 mg/mL delivers 40 mg in 0.4 mL. Clinical pearl: Do not expel the air bubble from a manufacturer-prefilled enoxaparin syringe, as it helps seal the dose in the tissue.

  14. Question 114. Scenario: A nurse prepares an intramuscular dose for an adult patient. Order: Administer 125 mg intramuscularly. Available: Vial labeled 250 mg per 5 mL. Question: How many milliliters should the nurse administer? Round to the nearest tenth if needed.

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    Correct answer: 2.5 mL Setup (dimensional analysis): 125 mg × (5 mL / 250 mg) = 2.5 mL Raw calculation: 125 × (5 ÷ 250) = 2.5 Rounding: Already to the tenth; no further rounding needed. Final answer: 2.5 mL Rationale: The vial contains 250 mg per 5 mL (50 mg/mL). The mg units cancel, leaving mL. Clinical pearl: When a concentration is expressed as "X mg per Y mL," first note mg/mL (here 50 mg/mL) before solving.

  15. Question 115. Scenario: A provider writes an insulin order in milliliters, which the nurse must convert to units. Order: Administer 0.5 mL of U-100 insulin subcutaneously. Available: U-100 insulin (100 units per mL). Question: How many units does this order represent? Round to a whole unit if needed.

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    Correct answer: 50 units Setup (dimensional analysis): 0.5 mL × (100 units / 1 mL) = 50 units Raw calculation: 0.5 × 100 = 50 Rounding: Whole unit; no rounding needed. Final answer: 50 units Rationale: U-100 insulin is 100 units/mL, so 0.5 mL equals 50 units. The mL units cancel. Clinical pearl: 0.5 mL of U-100 insulin exactly fills a 0.5-mL (50-unit) insulin syringe.

  16. Question 116. Scenario: A nurse prepares an intramuscular injection for an adult patient. Order: Administer 75 mg intramuscularly. Available: Vial labeled 50 mg per mL. Question: How many milliliters should the nurse administer? Choose the correct answer: A) 0.67 mL B) 1.5 mL C) 2.5 mL D) 3.75 mL

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    Correct answer: B) 1.5 mL Setup (dimensional analysis): 75 mg × (1 mL / 50 mg) = 1.5 mL Raw calculation: 75 ÷ 50 = 1.5 Rounding: Already to the tenth; no further rounding needed. Final answer: 1.5 mL Rationale: The mg units cancel, leaving mL. The distractors represent common errors (inverting the fraction gives 0.67 mL; multiplying gives 3.75 mL). Clinical pearl: A 50 mg/mL concentration means every 0.1 mL contains 5 mg; 75 mg requires 1.5 mL.

  17. Question 117. Scenario: A pediatric clinic nurse must administer a very small volume by injection. Order: Administer 0.05 mL intramuscularly. Available: Tuberculin (1-mL) syringe (0.01-mL increments); 3-mL syringe (0.1-mL increments). Question: Which syringe can accurately measure 0.05 mL? No rounding needed.

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    Correct answer: Tuberculin (1-mL) syringe Setup (dimensional analysis): No calculation required (syringe selection). Raw calculation: N/A Rounding: N/A Final answer: Tuberculin (1-mL) syringe Rationale: 0.05 mL cannot be measured on a 3-mL syringe, whose smallest increment (0.1 mL) is larger than the dose. A tuberculin syringe calibrated in 0.01 mL can measure 0.05 mL accurately. Clinical pearl: A dose smaller than the syringe's smallest calibration increment cannot be measured accurately; choose a finer-graduated syringe.

  18. Question 118. Scenario: A nurse must administer a dose of 0.75 mL and select a syringe for accurate measurement. Order: Administer 0.75 mL intramuscularly. Available: 3-mL syringe calibrated in 0.1-mL increments; tuberculin (1-mL) syringe calibrated in 0.01-mL increments. Question: Which syringe accurately measures 0.75 mL, and why? No rounding needed.

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    Correct answer: Tuberculin (1-mL) syringe Setup (dimensional analysis): No calculation required (syringe selection). Raw calculation: N/A Rounding: N/A Final answer: Tuberculin (1-mL) syringe Rationale: 0.75 mL is 75 hundredths of a mL. A 3-mL syringe is marked only in tenths (0.1 mL), so 0.75 mL falls between the 0.7-mL and 0.8-mL lines and cannot be read precisely. A tuberculin syringe (0.01-mL increments) measures 0.75 mL exactly. Clinical pearl: When a dose includes a hundredths digit (e.g., 0.75 mL), use a tuberculin syringe; when it is in whole tenths, a 3-mL syringe suffices.

  19. Question 119. Scenario: A patient with diabetes requires a larger insulin dose. Order: Administer NPH insulin U-100 58 units subcutaneously. Available: U-100 insulin syringes: 0.3-mL (30-unit), 0.5-mL (50-unit), and 1-mL (100-unit). Question: Which syringe should be used, and to what marking should it be filled? No rounding needed.

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    Correct answer: 1-mL (100-unit) syringe, filled to the 58-unit mark Setup (dimensional analysis): No calculation required (syringe selection). Raw calculation: N/A Rounding: N/A Final answer: 1-mL (100-unit) U-100 insulin syringe, 58 units Rationale: 58 units exceeds the 50-unit capacity of a 0.5-mL syringe and the 30-unit capacity of a 0.3-mL syringe, so the 1-mL (100-unit) syringe must be used and filled to the 58-unit mark. Clinical pearl: Choose an insulin syringe whose maximum capacity exceeds the ordered dose; do not attempt to measure more units than a syringe holds.

  20. Question 120. Scenario: A patient requires two types of insulin that may be mixed in one syringe per current practice. Order: Administer NPH (intermediate-acting, cloudy) insulin 22 units and regular (short-acting, clear) insulin 8 units subcutaneously before breakfast. Available: U-100 NPH insulin vial; U-100 regular insulin vial; U-100 insulin syringe. Question: What total number of units should be in the syringe, and in what order should the two insulins be drawn up? No rounding needed.

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    Correct answer: 30 units total; draw up regular (clear) first, then NPH (cloudy) Setup (dimensional analysis): 22 units + 8 units = 30 units Raw calculation: 22 + 8 = 30 Rounding: N/A (whole units) Final answer: 30 units total; regular insulin drawn up first Rationale: NPH (intermediate-acting, cloudy) and regular (short-acting, clear) insulins are compatible for mixing. The total is 30 units. The short-acting (clear) regular insulin is drawn up first to prevent contaminating the clear vial with intermediate-acting insulin. Clinical pearl: "Clear before cloudy" — draw the clear (short-acting) insulin into the syringe before the cloudy (intermediate-acting) insulin when mixing.

  21. Question 121. Scenario: A nurse reviews a handwritten insulin order. Order: "Insulin 10.0 units subcutaneously before meals." Available: U-100 insulin. Question: Identify the medication-order error in this order. No calculation needed.

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    Correct answer: Trailing zero in "10.0 units" Setup (dimensional analysis): No calculation required (order-error identification). Raw calculation: N/A Rounding: N/A Final answer: The trailing zero ("10.0") should be removed; the order should read "10 units." Rationale: A trailing zero after a decimal point (10.0) is on The Joint Commission "Do Not Use" list because it can be misread as "100" if the decimal point is overlooked, causing a tenfold overdose. Clinical pearl: Never use a trailing zero (write "10 mg," not "10.0 mg"); always use a leading zero (write "0.5 mg," not ".5 mg").

  22. Question 122. Scenario: A nurse reviews a transcribed insulin order. Order: "Regular insulin 12 U subcutaneously." Available: U-100 insulin. Question: Identify the medication-order error in this order. No calculation needed.

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    Correct answer: Use of the abbreviation "U" for units Setup (dimensional analysis): No calculation required (order-error identification). Raw calculation: N/A Rounding: N/A Final answer: The order should read "12 units," not "12 U." Rationale: The abbreviation "U" is on The Joint Commission "Do Not Use" list because it can be misread as "0" (zero) or "4," leading to serious insulin dosing errors. "Units" must be written out. Clinical pearl: Write "units" in full; never use "U" for insulin or other medications ordered in units.

  23. Question 123. Scenario: A nurse prepares an intramuscular injection for an adult patient. Order: Administer 0.5 mg intramuscularly. Available: Vial labeled 0.4 mg per mL. Question: How many milliliters should the nurse administer? Round to the nearest hundredth if needed.

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    Correct answer: 1.25 mL Setup (dimensional analysis): 0.5 mg × (1 mL / 0.4 mg) = 1.25 mL Raw calculation: 0.5 ÷ 0.4 = 1.25 Rounding: Exact to the hundredth; no further rounding needed. Final answer: 1.25 mL Rationale: The mg units cancel, leaving mL. The result is exact at two decimal places. Clinical pearl: A volume such as 1.25 mL includes a hundredth that is not a whole tenth, so it cannot be read accurately on a 3-mL syringe (0.1-mL increments); use a tuberculin syringe (0.01-mL increments) for precision.

  24. Question 124. Scenario: A hospitalized patient requires subcutaneous heparin. Order: Administer heparin 6,000 units subcutaneously. Available: Vial labeled heparin 5,000 units per 0.5 mL. Question: How many milliliters should the nurse administer? Round to the nearest tenth if needed.

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    Correct answer: 0.6 mL Setup (dimensional analysis): 6,000 units × (0.5 mL / 5,000 units) = 0.6 mL Raw calculation: 6,000 × (0.5 ÷ 5,000) = 0.6 Rounding: Already to the tenth; no further rounding needed. Final answer: 0.6 mL Rationale: The concentration is 5,000 units per 0.5 mL (10,000 units/mL). The units cancel, leaving mL. Clinical pearl: Read the concentration exactly as printed on the label — "per 0.5 mL" differs from "per mL."

  25. Question 125. Scenario: A nurse prepares an intramuscular dose for an adult patient. Order: Administer 250 mg intramuscularly. Available: Vial labeled 1 g per 3 mL. Question: How many milliliters should the nurse administer? Round to the nearest hundredth if needed.

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    Correct answer: 0.75 mL Setup (dimensional analysis): 250 mg × (1,000 mg / 1 g)⁻¹ … equivalently 250 mg × (3 mL / 1,000 mg) = 0.75 mL Raw calculation: 250 × (3 ÷ 1,000) = 0.75 Rounding: Exact to the hundredth; no further rounding needed. Final answer: 0.75 mL Rationale: Convert 1 g to 1,000 mg. The vial is 1,000 mg per 3 mL, so 250 mg requires 0.75 mL. Units cancel correctly. Clinical pearl: Keep the "per g" and "per mg" conversions straight: 1 g = 1,000 mg before setting up the ratio.

  26. Question 126. Scenario: A nurse prepares an intramuscular injection. Order: Administer 80 mg intramuscularly. Available: Vial labeled 100 mg per 2 mL. Question: How many milliliters should the nurse administer? Round to the nearest tenth if needed.

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    Correct answer: 1.6 mL Setup (dimensional analysis): 80 mg × (2 mL / 100 mg) = 1.6 mL Raw calculation: 80 × (2 ÷ 100) = 1.6 Rounding: Already to the tenth; no further rounding needed. Final answer: 1.6 mL Rationale: The vial is 100 mg per 2 mL (50 mg/mL). The mg units cancel, leaving mL. Clinical pearl: A concentration of "100 mg per 2 mL" is the same as 50 mg/mL; choose whichever form makes the cancellation clearest.

  27. Question 127. Scenario: A nurse receives an intramuscular order and evaluates whether a single injection is appropriate. Order: Administer 4 mL intramuscularly as a single injection. Available: Typical educational maximum for a single adult IM injection is about 3 mL (larger muscles such as the ventrogluteal or vastus lateralis). Question: Is a single 4-mL injection appropriate? What should the nurse do? No calculation needed.

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    Correct answer: Not appropriate as a single injection; divide into two injections Setup (dimensional analysis): No calculation required (volume-safety judgment). Raw calculation: N/A Rounding: N/A Final answer: Divide the 4 mL into two separate injections (e.g., 2 mL each) at two sites. Rationale: A single 4-mL IM injection exceeds the typical educational maximum of about 3 mL per site for an adult's larger muscles. Large volumes increase pain and risk of tissue damage and poor absorption. Clinical pearl: Volumes above a site's typical maximum should be split between two sites (or two syringes) rather than given as one bolus.

  28. Question 128. Scenario: A nurse must give an intramuscular injection in the deltoid muscle of an adult. Order: Administer 2.5 mL intramuscularly in the deltoid. Available: Typical educational maximum for a deltoid IM injection is about 1 mL. Question: Is this deltoid injection volume appropriate? What should the nurse do? No calculation needed.

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    Correct answer: Not appropriate for the deltoid; use a larger muscle or split the dose Setup (dimensional analysis): No calculation required (volume-safety judgment). Raw calculation: N/A Rounding: N/A Final answer: Do not give 2.5 mL in the deltoid; use the ventrogluteal or vastus lateralis, or divide the dose. Rationale: The deltoid's typical educational maximum is about 1 mL. A 2.5-mL injection exceeds that and risks pain, tissue injury, and unreliable absorption. A larger muscle site or a split dose is needed. Clinical pearl: Match injection volume to the muscle: small muscles (deltoid) hold less than large muscles (ventrogluteal, vastus lateralis).

  29. Question 129. Scenario: A nurse evaluates a subcutaneous injection order. Order: Administer 2 mL subcutaneously as a single injection. Available: Typical educational maximum for a single subcutaneous injection is about 1 mL. Question: Is a single 2-mL subcutaneous injection appropriate? What should the nurse do? No calculation needed.

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    Correct answer: Not appropriate as a single subcutaneous injection; reassess or split Setup (dimensional analysis): No calculation required (volume-safety judgment). Raw calculation: N/A Rounding: N/A Final answer: Do not give 2 mL as a single subcutaneous injection; clarify the order or split the dose. Rationale: A typical educational maximum for a single subcutaneous injection is about 1 mL. Two mL exceeds this, increasing leakage, discomfort, and erratic absorption. Clinical pearl: Subcutaneous injections are generally limited to about 1 mL; larger volumes should be questioned or divided.

  30. Question 130. Scenario: A nurse reads the volume in a 3-mL syringe calibrated in 0.1-mL increments. Order: The plunger's top ring rests on the second small graduation below the 2.4-mL line. Available: 3-mL syringe (0.1-mL increments). Question: What volume (in mL) is indicated? Choose the correct answer: A) 2.2 mL B) 2.4 mL C) 2.02 mL D) 2.6 mL

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    Correct answer: A) 2.2 mL Setup (dimensional analysis): 2.4 mL − (2 × 0.1 mL) = 2.2 mL Raw calculation: 2.4 − 0.2 = 2.2 Rounding: N/A Final answer: 2.2 mL Rationale: On a 3-mL syringe each graduation is 0.1 mL; two graduations below 2.4 mL is 2.2 mL. The distractor 2.02 mL misreads the hundredths place. Clinical pearl: On a 0.1-mL-graduated syringe, count each small line as a tenth of a mL.

  31. Question 131. Scenario: A nurse reads a tuberculin (1-mL) syringe calibrated in 0.01-mL increments. Order: The plunger's top ring rests on the second small graduation above the 0.7-mL line. Available: Tuberculin (1-mL) syringe (0.01-mL increments). Question: What volume (in mL) is indicated? Choose the correct answer: A) 0.62 mL B) 0.72 mL C) 0.82 mL D) 0.7 mL

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    Correct answer: B) 0.72 mL Setup (dimensional analysis): 0.7 mL + (2 × 0.01 mL) = 0.72 mL Raw calculation: 0.7 + 0.02 = 0.72 Rounding: N/A Final answer: 0.72 mL Rationale: On a tuberculin syringe each graduation is 0.01 mL; two graduations above 0.7 mL is 0.72 mL. Clinical pearl: On a tuberculin syringe, the labeled numbers are tenths and each small line between them is one hundredth.

  32. Question 132. Scenario: A nurse documents the volume administered and must determine the dose actually delivered. Order: The provider had ordered 20 mg; the nurse administered 0.8 mL. Available: Vial labeled 25 mg per mL. Question: How many milligrams did the patient receive? Round to the nearest whole mg if needed.

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    Correct answer: 20 mg Setup (dimensional analysis): 0.8 mL × (25 mg / 1 mL) = 20 mg Raw calculation: 0.8 × 25 = 20 Rounding: Whole number; no rounding needed. Final answer: 20 mg Rationale: Multiplying the administered volume by the concentration (25 mg/mL) yields the dose delivered. The mL units cancel. Clinical pearl: To determine the dose actually given, multiply the volume drawn up by the concentration on the vial.

  33. Question 133. Scenario: A nurse reviews what was administered during a code situation. Order: The nurse gave 1.5 mL of the available concentration. Available: Vial labeled 40 mg per mL. Question: How many milligrams were delivered? Round to the nearest whole mg if needed.

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    Correct answer: 60 mg Setup (dimensional analysis): 1.5 mL × (40 mg / 1 mL) = 60 mg Raw calculation: 1.5 × 40 = 60 Rounding: Whole number; no rounding needed. Final answer: 60 mg Rationale: The concentration is 40 mg/mL, so 1.5 mL delivers 60 mg. The mL units cancel. Clinical pearl: Reverse calculations (volume → dose) use the same conversion factor, inverted.

  34. Question 134. Scenario: A nurse reviews an order to mix two insulins in one syringe. Order: "Mix insulin glargine (long-acting, clear) 20 units with NPH insulin 10 units in one syringe." Available: U-100 insulin glargine vial; U-100 NPH insulin vial. Question: What is the problem with this order, and what should the nurse do? No calculation needed.

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    Correct answer: Insulin glargine must not be mixed with other insulins; give as separate injections Setup (dimensional analysis): No calculation required (compatibility judgment). Raw calculation: N/A Rounding: N/A Final answer: Do not mix glargine; clarify the order and administer the two insulins as separate injections. Rationale: Insulin glargine (long-acting, clear) is not compatible for mixing with other insulins. Mixing can alter its absorption profile and cause unpredictable glycemic control. The nurse should not mix them and should administer separately (and verify the order). Clinical pearl: Never assume all insulins can be mixed — check compatibility; long-acting insulins such as glargine are given separately.

  35. Question 135. Scenario: A nurse prepares an intramuscular injection for an adult patient. Order: Administer 0.3 mg intramuscularly. Available: Vial labeled 0.5 mg per mL. Question: How many milliliters should the nurse administer? Round to the nearest tenth if needed.

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    Correct answer: 0.6 mL Setup (dimensional analysis): 0.3 mg × (1 mL / 0.5 mg) = 0.6 mL Raw calculation: 0.3 ÷ 0.5 = 0.6 Rounding: Already to the tenth; no further rounding needed. Final answer: 0.6 mL Rationale: The mg units cancel, leaving mL. A 0.5 mg/mL concentration requires 0.6 mL for a 0.3-mg dose. Clinical pearl: With a 0.5 mg/mL concentration, every 0.1 mL delivers 0.05 mg.

  36. Question 136. Scenario: A patient receives a subcutaneous medication. Order: Administer 30 mg subcutaneously. Available: Vial labeled 100 mg per mL. Question: How many milliliters should the nurse administer? Round to the nearest tenth if needed.

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    Correct answer: 0.3 mL Setup (dimensional analysis): 30 mg × (1 mL / 100 mg) = 0.3 mL Raw calculation: 30 ÷ 100 = 0.3 Rounding: Already to the tenth; no further rounding needed. Final answer: 0.3 mL Rationale: The mg units cancel, leaving mL. A 100 mg/mL concentration delivers 30 mg in 0.3 mL. Clinical pearl: Small subcutaneous doses measured in tenths of a mL can be drawn with a tuberculin syringe for accuracy.

  37. Question 137. Scenario: A nurse prepares an intramuscular dose. Order: Administer 375 mg intramuscularly. Available: Vial labeled 250 mg per mL. Question: How many milliliters should the nurse administer? Round to the nearest tenth if needed.

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    Correct answer: 1.5 mL Setup (dimensional analysis): 375 mg × (1 mL / 250 mg) = 1.5 mL Raw calculation: 375 ÷ 250 = 1.5 Rounding: Already to the tenth; no further rounding needed. Final answer: 1.5 mL Rationale: The mg units cancel, leaving mL. A 250 mg/mL concentration requires 1.5 mL for 375 mg. Clinical pearl: 375 mg is 1.5 × 250 mg, so the volume is 1.5 × 1 mL = 1.5 mL.

  38. Question 138. Scenario: A nurse interprets a vial label to determine the dose volume. Order: Administer 150 mg intramuscularly. Available: Vial label reads "100 mg per 2 mL." Question: How many milliliters should the nurse administer? Round to the nearest whole mL if needed.

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    Correct answer: 3 mL Setup (dimensional analysis): 150 mg × (2 mL / 100 mg) = 3 mL Raw calculation: 150 × (2 ÷ 100) = 3 Rounding: Whole number; no rounding needed. Final answer: 3 mL Rationale: The label "100 mg per 2 mL" means 50 mg/mL. For 150 mg, the volume is 3 mL. The mg units cancel. Clinical pearl: Always read the label concentration carefully — "per 2 mL" is not the same as "per mL."

  39. Question 139. Scenario: A nurse interprets a multi-dose vial label. Order: Administer 300 mg intramuscularly. Available: Vial label reads "1 gram per 10 mL." Question: How many milliliters should the nurse administer? Round to the nearest whole mL if needed.

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    Correct answer: 3 mL Setup (dimensional analysis): 300 mg × (10 mL / 1,000 mg) = 3 mL Raw calculation: 300 × (10 ÷ 1,000) = 3 Rounding: Whole number; no rounding needed. Final answer: 3 mL Rationale: Convert 1 g to 1,000 mg. The vial is 1,000 mg per 10 mL (100 mg/mL), so 300 mg requires 3 mL. Clinical pearl: A "1 gram per 10 mL" label is 100 mg/mL; convert grams to milligrams before solving.

  40. Question 140. Scenario: A patient with diabetes is prescribed a weight-based total daily insulin dose. Order: Administer U-100 insulin 0.6 units per kg per day (hypothetical educational protocol). Available: U-100 insulin. Patient weight 70 kg. Question: What is the total daily insulin dose in units? Round to a whole unit if needed.

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    Correct answer: 42 units per day Setup (dimensional analysis): 70 kg × (0.6 units / 1 kg) = 42 units/day Raw calculation: 70 × 0.6 = 42 Rounding: Whole unit; no rounding needed. Final answer: 42 units per day Rationale: Multiplying weight by the per-kg dose gives the total daily insulin in units. The kg units cancel. Clinical pearl: For weight-based insulin, multiply the ordered units/kg by the patient's weight in kg (kg = lb ÷ 2.2 when only pounds are given).

  41. Question 141. Scenario: A nurse prepares an intramuscular injection. Order: Administer 0.6 mg intramuscularly. Available: Vial labeled 0.4 mg per mL. Question: How many milliliters should the nurse administer? Choose the correct answer: A) 0.24 mL B) 1.5 mL C) 2.4 mL D) 0.67 mL

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    Correct answer: B) 1.5 mL Setup (dimensional analysis): 0.6 mg × (1 mL / 0.4 mg) = 1.5 mL Raw calculation: 0.6 ÷ 0.4 = 1.5 Rounding: Already to the tenth; no further rounding needed. Final answer: 1.5 mL Rationale: The mg units cancel, leaving mL. Distractor 0.24 mL inverts the fraction (0.6 × 0.4); 2.4 mL multiplies instead of dividing. Clinical pearl: Estimate first — 0.6 mg is 1.5 times 0.4 mg, so the volume must be about 1.5 times 1 mL.

  42. Question 142. Scenario: A nurse must administer a small measured volume by injection. Order: Administer 0.15 mL subcutaneously. Available: 3-mL syringe calibrated in 0.1-mL increments; tuberculin (1-mL) syringe calibrated in 0.01-mL increments. Question: Which syringe accurately measures 0.15 mL? No rounding needed.

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    Correct answer: Tuberculin (1-mL) syringe Setup (dimensional analysis): No calculation required (syringe selection). Raw calculation: N/A Rounding: N/A Final answer: Tuberculin (1-mL) syringe Rationale: 0.15 mL lies between the 0.1-mL and 0.2-mL marks of a 3-mL syringe and cannot be read accurately. A tuberculin syringe (0.01-mL increments) measures 0.15 mL precisely. Clinical pearl: A hundredths digit in the dose (0.15 mL) requires a syringe calibrated in hundredths.

  43. Question 143. Scenario: A patient with diabetes is prescribed a weight-based insulin regimen. Order: U-100 insulin 0.5 units per kg per day, given as two-thirds before breakfast and one-third before the evening meal (hypothetical educational protocol). Available: U-100 insulin. Patient weight 60 kg. Question: How many units should be given before breakfast, and how many before the evening meal? Round each to a whole unit.

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    Correct answer: 20 units before breakfast; 10 units before the evening meal Setup (dimensional analysis): Total = 60 kg × 0.5 units/kg = 30 units/day. Breakfast = 30 × (2/3) = 20 units; Evening = 30 × (1/3) = 10 units. Raw calculation: 60 × 0.5 = 30; 30 × 2/3 = 20; 30 × 1/3 = 10. Rounding: Already whole units; no rounding needed. Final answer: 20 units before breakfast; 10 units before the evening meal Rationale: Total daily dose is 30 units. Two-thirds (20 units) is given before breakfast and one-third (10 units) before the evening meal. The two doses sum to 30 units. Clinical pearl: When a protocol splits a total daily dose, verify that the parts add back up to the calculated total.

  44. Question 144. Scenario: A patient with an acute coronary syndrome requires an intravenous heparin bolus. Order: Heparin 80 units per kg IV bolus (hypothetical educational protocol). Available: Heparin 5,000 units per mL. Patient weight 70 kg. Question: How many units should be administered, and how many milliliters does this equal? Round mL to the nearest hundredth.

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    Correct answer: 5,600 units; 1.12 mL Setup (dimensional analysis): 70 kg × 80 units/kg = 5,600 units. Then 5,600 units × (1 mL / 5,000 units) = 1.12 mL. Raw calculation: 70 × 80 = 5,600; 5,600 ÷ 5,000 = 1.12. Rounding: 1.12 mL is already to the hundredth; no further rounding needed. Final answer: 5,600 units = 1.12 mL Rationale: Weight-based bolus: multiply weight by units/kg to get total units, then convert units to mL using the concentration (5,000 units/mL). Clinical pearl: For weight-based boluses, always compute total units first, then convert to volume.

  45. Question 145. Scenario: A patient requires a continuous heparin infusion. Order: Heparin 1,000 units per hour IV (hypothetical educational protocol). Available: Heparin 25,000 units in 500 mL D5W. Question: What is the infusion rate in mL per hour? Round to the nearest whole mL/hr if needed.

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    Correct answer: 20 mL/hr Setup (dimensional analysis): Concentration = 25,000 units / 500 mL = 50 units/mL. Then 1,000 units/hr × (1 mL / 50 units) = 20 mL/hr. Raw calculation: 25,000 ÷ 500 = 50; 1,000 ÷ 50 = 20. Rounding: Whole number; no rounding needed. Final answer: 20 mL/hr Rationale: Determine the concentration in units/mL, then divide the ordered units/hr by that concentration. The units cancel, leaving mL/hr. Clinical pearl: For infusions, first compute units/mL (total units ÷ total volume), then divide the ordered rate by that concentration.

  46. Question 146. Scenario: A patient with hyperglycemia requires an IV insulin infusion. Order: Regular insulin 6 units per hour IV (hypothetical educational protocol). Available: Regular insulin 100 units in 100 mL normal saline. Question: What is the infusion rate in mL per hour? Round to the nearest whole mL/hr if needed.

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    Correct answer: 6 mL/hr Setup (dimensional analysis): Concentration = 100 units / 100 mL = 1 unit/mL. Then 6 units/hr × (1 mL / 1 unit) = 6 mL/hr. Raw calculation: 100 ÷ 100 = 1; 6 ÷ 1 = 6. Rounding: Whole number; no rounding needed. Final answer: 6 mL/hr Rationale: The infusion is 1 unit/mL, so the mL/hr rate equals the units/hr rate. The units cancel. Clinical pearl: A "1 unit per mL" insulin infusion makes the mL/hr and units/hr values identical — a useful safety check.

  47. Question 147. Scenario: A nurse verifies a weight-based parenteral dose for a child. Order: Administer 75 mg intramuscularly. Available: Hypothetical safe range 1–2 mg per kg per dose. Child weight 50 kg. Question: Is the ordered dose safe? Show the safe range and state your conclusion.

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    Correct answer: SAFE Setup (dimensional analysis): Safe range = 1–2 mg/kg/dose × 50 kg = 50–100 mg/dose. Raw calculation: 1 × 50 = 50 mg; 2 × 50 = 100 mg. Rounding: N/A Final answer: SAFE — 75 mg is within the 50–100 mg/dose safe range Rationale: Converted weight: 50 kg (already in kg). Minimum safe dose: 1 mg/kg × 50 kg = 50 mg. Maximum safe dose: 2 mg/kg × 50 kg = 100 mg. Ordered dose: 75 mg (per dose). 75 mg lies within 50–100 mg, so the dose is SAFE. Clinical pearl: State the weight in kg, compute the low and high ends of the range, then place the ordered dose between them.

  48. Question 148. Scenario: A nurse verifies a weight-based parenteral dose for a child. Order: Administer 250 mg intramuscularly. Available: Hypothetical safe range 2–3 mg per kg per dose. Child weight 60 kg. Question: Is the ordered dose safe? Show the safe range and state your conclusion.

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    Correct answer: UNSAFE Setup (dimensional analysis): Safe range = 2–3 mg/kg/dose × 60 kg = 120–180 mg/dose. Raw calculation: 2 × 60 = 120 mg; 3 × 60 = 180 mg. Rounding: N/A Final answer: UNSAFE — 250 mg exceeds the 120–180 mg/dose safe range; clarify with the provider Rationale: Converted weight: 60 kg (already in kg). Minimum safe dose: 2 mg/kg × 60 kg = 120 mg. Maximum safe dose: 3 mg/kg × 60 kg = 180 mg. Ordered dose: 250 mg. Because 250 mg exceeds the maximum safe dose of 180 mg, the dose is UNSAFE and must be clarified before administration. Clinical pearl: A dose above the maximum safe range is a "hold and clarify" situation, not a "give a little less" decision.

  49. Question 149. Scenario: A nurse reviews the amount of a medication delivered by infusion. Order: The infusion delivered 12 mL per hour for 2 hours. Available: Medication concentration 50 units per mL. Question: How many total units were delivered over the 2 hours? Round to a whole unit if needed.

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    Correct answer: 1,200 units Setup (dimensional analysis): 12 mL/hr × 2 hr = 24 mL. Then 24 mL × (50 units / 1 mL) = 1,200 units. Raw calculation: 12 × 2 = 24; 24 × 50 = 1,200. Rounding: Whole number; no rounding needed. Final answer: 1,200 units Rationale: First find the total volume infused over 2 hours, then multiply by the concentration (50 units/mL). The mL and hr units cancel appropriately. Clinical pearl: For total dose delivered, multiply rate × time to get volume, then volume × concentration to get total amount.

  50. Question 150. Scenario: A patient's blood glucose requires a correction dose of insulin. Order: Correction insulin per hypothetical sliding scale: 150–200 mg/dL → 2 units; 201–250 mg/dL → 4 units; 251–300 mg/dL → 6 units; 301–350 mg/dL → 8 units. Available: U-100 insulin. Blood glucose is 268 mg/dL. Question: How many units of correction insulin should be given? No rounding needed.

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    Correct answer: 6 units Setup (dimensional analysis): Blood glucose 268 mg/dL falls in the 251–300 mg/dL band. Raw calculation: N/A (scale interpretation) Rounding: N/A Final answer: 6 units Rationale: The hypothetical sliding scale assigns 6 units to readings of 251–300 mg/dL; 268 mg/dL is in that band. Clinical pearl: With a sliding scale, locate the glucose value within the correct band — do not interpolate between bands.

  51. Question 151. Scenario: A patient with severe insulin resistance is prescribed concentrated insulin. Order: Administer U-500 insulin 100 units subcutaneously. Available: U-500 insulin (500 units per mL). Question: How many milliliters equal 100 units? Round to the nearest tenth. Also state which syringe type should be used.

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    Correct answer: 0.2 mL; use a tuberculin syringe (or a syringe calibrated for U-500) Setup (dimensional analysis): 100 units × (1 mL / 500 units) = 0.2 mL Raw calculation: 100 ÷ 500 = 0.2 Rounding: Already to the tenth; no further rounding needed. Final answer: 0.2 mL Rationale: U-500 insulin is 500 units/mL (five times the concentration of U-100). The units cancel, leaving mL. Because U-500 is concentrated, it must be measured with a tuberculin syringe (or a dedicated U-500 syringe) — never a U-100 insulin syringe, which would deliver a fivefold overdose. Clinical pearl: U-500 insulin is measured in mL (not units) on a tuberculin syringe; using a U-100 syringe for U-500 insulin is a serious error.

  52. Question 152. Scenario: A nurse reconstitutes an intramuscular antibiotic. Order: Administer 500 mg intramuscularly. Available: 1 g vial. Reconstitution: add 3.5 mL diluent to yield a total volume of 4 mL. Question: What is the concentration after reconstitution, and how many milliliters should be administered? Round to the nearest tenth.

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    Correct answer: 250 mg/mL; 2 mL Setup (dimensional analysis): Concentration = 1,000 mg / 4 mL = 250 mg/mL. Then 500 mg × (1 mL / 250 mg) = 2 mL. Raw calculation: 1,000 ÷ 4 = 250; 500 ÷ 250 = 2. Rounding: Whole number; no rounding needed. Final answer: 2 mL Rationale: The 1 g (1,000 mg) vial reconstituted to 4 mL yields 250 mg/mL. A 500-mg dose requires 2 mL. The mg units cancel. Clinical pearl: After reconstitution, always recalculate the concentration from the actual final volume printed on the label or directions.

  53. Question 153. Scenario: A nurse chooses a reconstitution concentration to minimize injection volume. Order: Administer 400 mg intramuscularly. Available: 1 g vial. Option A: add 1.8 mL diluent to yield 2 mL total (500 mg/mL). Option B: add 3.8 mL diluent to yield 4 mL total (250 mg/mL). Question: Which concentration minimizes injection volume, and how many milliliters should be administered? Round to the nearest tenth.

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    Correct answer: Option A (500 mg/mL); 0.8 mL Setup (dimensional analysis): Option A: 400 mg × (2 mL / 1,000 mg) = 0.8 mL. Option B: 400 mg × (4 mL / 1,000 mg) = 1.6 mL. Raw calculation: 400 × (2 ÷ 1,000) = 0.8; 400 × (4 ÷ 1,000) = 1.6. Rounding: Already to the tenth; no further rounding needed. Final answer: 0.8 mL using Option A (500 mg/mL) Rationale: The more concentrated solution (500 mg/mL) delivers 400 mg in only 0.8 mL, versus 1.6 mL at 250 mg/mL. A smaller volume reduces injection discomfort and tissue irritation. Clinical pearl: When a vial offers multiple reconstitution concentrations, choose the one that minimizes the injection volume while remaining accurately measurable.

  54. Question 154. Scenario: A nurse mixes two insulins in one syringe using current practice. Order: Administer NPH (intermediate-acting, cloudy) insulin 24 units and regular (short-acting, clear) insulin 6 units subcutaneously. Available: U-100 NPH vial; U-100 regular vial; U-100 insulin syringe. Question: What is the total number of units in the syringe, and which insulin is drawn up first? No rounding needed.

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    Correct answer: 30 units total; regular (clear) drawn up first Setup (dimensional analysis): 24 units + 6 units = 30 units Raw calculation: 24 + 6 = 30 Rounding: N/A (whole units) Final answer: 30 units total; regular insulin drawn up first Rationale: NPH (cloudy, intermediate-acting) and regular (clear, short-acting) insulins may be mixed. Total units = 30. Draw up the regular (clear) insulin first to avoid contaminating the regular vial with intermediate-acting insulin. Clinical pearl: "Clear before cloudy" — the short-acting (clear) insulin is drawn first, then the intermediate-acting (cloudy) insulin.

  55. Question 155. Scenario: A nurse must give a large intramuscular volume and plan the number of injection sites. Order: Administer a total of 4.5 mL intramuscularly. Available: Typical educational maximum of about 3 mL per adult IM site. Question: Into how many separate injections should the total dose be divided? No rounding needed.

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    Correct answer: 2 injections Setup (dimensional analysis): 4.5 mL ÷ 3 mL/site ≈ 1.5 sites → round up to 2 sites. Raw calculation: 4.5 ÷ 3 = 1.5 Rounding: Round up to the next whole number of injection sites. Final answer: 2 injections (e.g., 2.25 mL each, or 3 mL + 1.5 mL) Rationale: A single site typically holds a maximum of about 3 mL. Since 4.5 mL exceeds 3 mL, it must be divided between two sites. Clinical pearl: When a total dose exceeds the per-site maximum, divide the volume (as evenly as practical) and document both sites.

  56. Question 156. Scenario: A nurse reads a large-volume syringe. Order: The plunger's top ring rests on the third small graduation below the 4-mL line of a 5-mL syringe calibrated in 0.2-mL increments. Available: 5-mL syringe (0.2-mL increments). Question: What volume (in mL) is indicated? No rounding needed.

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    Correct answer: 3.4 mL Setup (dimensional analysis): 4 mL − (3 × 0.2 mL) = 3.4 mL Raw calculation: 4 − 0.6 = 3.4 Rounding: N/A Final answer: 3.4 mL Rationale: A 5-mL syringe calibrated in 0.2-mL increments has lines every 0.2 mL. Three graduations below 4 mL is 3.4 mL. Clinical pearl: On a 0.2-mL-graduated syringe, each small line is 0.2 mL; count backward from a labeled line carefully.

  57. Question 157. Scenario: A nurse plans to combine two compatible medications in one syringe for a single intramuscular injection. Order: Administer 0.3 mL of medication A and 0.25 mL of medication B intramuscularly (compatible, same route). Available: Tuberculin (1-mL) syringe. Question: What total volume will be in the syringe, and is a single injection appropriate? No rounding needed.

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    Correct answer: 0.55 mL total; a single injection is appropriate Setup (dimensional analysis): 0.3 mL + 0.25 mL = 0.55 mL Raw calculation: 0.3 + 0.25 = 0.55 Rounding: N/A Final answer: 0.55 mL in one syringe; single intramuscular injection is appropriate Rationale: The combined volume is 0.55 mL, which is well below the typical ~3-mL maximum for a single adult IM injection, so one injection is appropriate (assuming the medications are confirmed compatible). Clinical pearl: When combining compatible medications in one syringe, add the volumes and verify the total does not exceed the site's typical maximum.

  58. Question 158. Scenario: A patient with a pulmonary embolism is started on a heparin protocol. Order: Hypothetical protocol: (1) heparin bolus 60 units per kg IV, then (2) continuous infusion 18 units per kg per hour. Available: Bolus heparin 1,000 units per mL; infusion heparin 25,000 units in 250 mL D5W. Patient weight 82 kg. Question: How many milliliters for the bolus, and what infusion rate in mL per hour? Round the bolus to the nearest hundredth and the infusion to the nearest tenth.

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    Correct answer: Bolus 4.92 mL; infusion 14.8 mL/hr Setup (dimensional analysis): Bolus units = 82 kg × 60 units/kg = 4,920 units; bolus mL = 4,920 units × (1 mL / 1,000 units) = 4.92 mL. Infusion units = 82 kg × 18 units/kg/hr = 1,476 units/hr; concentration = 25,000 units / 250 mL = 100 units/mL; rate = 1,476 units/hr × (1 mL / 100 units) = 14.76 mL/hr. Raw calculation: 82 × 60 = 4,920; 4,920 ÷ 1,000 = 4.92; 82 × 18 = 1,476; 25,000 ÷ 250 = 100; 1,476 ÷ 100 = 14.76. Rounding: Bolus 4.92 mL (hundredth, exact). Infusion 14.76 → 14.8 mL/hr (nearest tenth). Final answer: Bolus 4.92 mL; infusion 14.8 mL/hr Rationale: Both parts use weight-based units/kg first, then conversion to volume using each solution's concentration. The infusion rate 14.76 rounds to 14.8 mL/hr on a tenth-calibrated pump. Clinical pearl: In weight-based protocols, compute total units first, then convert; round only the final pump setting.

  59. Question 159. Scenario: A patient uses an insulin pump-free basal-bolus regimen with meal and correction coverage. Order: Hypothetical protocol: correction scale 120–160 mg/dL → 2 units; 161–200 mg/dL → 4 units; 201–240 mg/dL → 6 units; 241–280 mg/dL → 8 units. Carbohydrate ratio: 1 unit per 15 g. Available: U-100 insulin. Blood glucose 190 mg/dL; meal contains 60 g carbohydrate. Question: How many total units of rapid-acting insulin should be given? Round to a whole unit.

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    Correct answer: 8 units Setup (dimensional analysis): Correction = 4 units (BG 190 mg/dL is in the 161–200 band). Carbohydrate coverage = 60 g × (1 unit / 15 g) = 4 units. Total = 4 + 4 = 8 units. Raw calculation: 60 ÷ 15 = 4; 4 + 4 = 8. Rounding: Whole unit; no rounding needed. Final answer: 8 units Rationale: The blood glucose of 190 mg/dL falls in the 161–200 mg/dL band (4 units correction). The 60 g carbohydrate meal at a 1 unit per 15 g ratio needs 4 units of coverage. Total rapid-acting insulin = 8 units. Clinical pearl: Add the correction dose and the carbohydrate-coverage dose to obtain the total mealtime bolus.

  60. Question 160. Scenario: A nurse verifies and prepares a pediatric intramuscular dose from a reconstituted vial. Order: Administer cefazolin 25 mg per kg per dose intramuscularly. Available: 1 g vial. Reconstitution: add 3 mL diluent to yield a total volume of 4 mL. Hypothetical safe range 20–40 mg per kg per dose. Child weight 18 kg. Question: Is the ordered dose safe? How many milliliters should be administered, and which syringe is most appropriate? Round mL to the nearest tenth.

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    Correct answer: SAFE; 1.8 mL using a 3-mL syringe Setup (dimensional analysis): Dose = 18 kg × 25 mg/kg = 450 mg. Safe range = 20–40 mg/kg/dose × 18 kg = 360–720 mg. Concentration = 1,000 mg / 4 mL = 250 mg/mL. Volume = 450 mg × (1 mL / 250 mg) = 1.8 mL. Raw calculation: 18 × 25 = 450; 20 × 18 = 360; 40 × 18 = 720; 1,000 ÷ 4 = 250; 450 ÷ 250 = 1.8. Rounding: 1.8 mL is already to the tenth; no further rounding needed. Final answer: SAFE; administer 1.8 mL with a 3-mL syringe Rationale: Converted weight: 18 kg (already in kg). Minimum safe dose: 20 mg/kg × 18 kg = 360 mg. Maximum safe dose: 40 mg/kg × 18 kg = 720 mg. Ordered dose: 25 mg/kg × 18 kg = 450 mg, which is within 360–720 mg → SAFE. The reconstituted concentration is 250 mg/mL, so 450 mg = 1.8 mL. A 3-mL syringe (0.1-mL increments) accurately measures 1.8 mL. Clinical pearl: Multi-step problems follow one order: verify safety, calculate concentration, compute volume, then select the correct syringe.

    Verification: Authored 60 questions (Q101–Q160); self-check count == 60; re-solved 12 (Q104, Q111, Q123, Q124, Q137, Q138, Q143, Q144, Q145, Q151, Q158, Q160); all arithmetic matches.

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