79. A child recovering from abdominal surgery is receiving morphine for pain via PCA at a concentration of 1 mg/mL. The child receives a basal rate of 1 mg/hr and is able to selfadminister up to four 1-mg boluses each hour. A nurse hangs a 50-mL syringe at the start of the shift and reviews the child's PCA record 4 hours later to find that the child self-administered a total of 7 boluses during that time. The nurse calculates that _______ mL of morphine should be left in the syringe.
Test-Taking Tip
Do not be confused by extra information in pharmacology questions. For this item, the information states the child can only self-administer up to 4 boluses per hour. This information is not to be considered; no information is given regarding the number of boluses the child administered in a single hour—only the total amount for a 4-hour period.
Content Area: Child Health, Pharmacology; Integrated Process: Nursing Process, Analysis; Cognitive Level: Analysis; Client Need/Subneed: Physiological Integrity/Pharmacological and Parenteral Therapies/Dosage Calculation
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To solve this calculation, first determine how many mL of morphine has been administered over the past 4 hours. The child has selfadministered 7 boluses of 1 mg each. If the syringe has a concentration of 1 mg/1 mL, the child has received 7 mL. The basal rate is 1 mg/hr; 4 hours at this rate is equal to 4 mL. Add the self-administered doses to the basal rate to get a total of 11 mL administered in 4 hours. Finally, subtract 11 mL from the 50-mL syringe starting volume to arrive at the correct response of 39 mL left in the syringe after 4 hours.