IV Calculation

Nursing Students Student Assist

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Hi guys. I'm a first semester nursing student and I'd like to pick your brains for a minute. I find health calculations simple because the math never changes, it all boils down to extracting the pertinent information from the problem and solving for whatever. That being said, I'm having difficulty with medical terminology here and there and its usage in those problems. Not that I don't understand the abbreviations, but once I have been told that a certain acronym means one thing and nothing else, I interpret it that way. We have been given several problems on our quizzes and even a few exam questions that I feel may skew terminology somewhat which creates confusion. I know that confusion is a necessary evil in nursing school, but I feel that medical terminology shouldn't be messed with when it comes to drug calculations because it creates a potential for mistakes if you interpret xyz differently than I do. Here's an example, please tell me if I am mistaken:

At 1600, the doctor orders 1L of D5W q8h. The nurse starts the liter at 1800. The patient receives xxxxxxxx 0.5g in 100 mL 0.9% sodium chloride at 2200. Calculate the patients 8 hr parenteral intake for the 1600-0000 shift.

-My answer is 1,100 mL. This is total intake for the 8 hr period

-I interpret the question this way: The facts- 1L q8h(every 8 hours) + 100 mL. The medication was all received within the 8 hr window, so I add it all together and thats my total. The question does not indicate the infusion time for the medication. But if I interpret the q8h as meaning "over 8 hours" I would have to factor in that the medication started two hours after the order, so that would only be 6 hours of medication infusion, plus the 100 mL. My total would then be 850 mL. That is the answer my instructor gave, and I was marked wrong. While I realize that it doesn't make sense to infuse instantly 1L of iv meds, reasonable people would realize the instructor means to calculate based on infusion time over 8 hrs. But I look at what I see and interpret it literally. Am I wrong? Real world I would question the intentions, but this is a test so I can't do that.

Thanks for the reply! I understand the rationale for the answer, but I guess my dilemma is trying to figure out if my instructor was correct in using q8h as meaning "over 8 hours" instead of "every 8 hours", as all literature I can find states the definition is the latter- with no exceptions. I came to my conclusion with the understanding that if I use the literal definition I don't have an infusion time. To me, how a person interprets that changes the question altogether. The instructor has stressed the importance of reading literally and not to make assumptions. I'm just trying to understand why we are taught a system that is supposed to be standardized, it is appropriate to alter the actual definition depending on needs at the moment

IVs are prescribed several ways-- "1000cc over 8hours" is not the same as "1000cc q8h," which is the same as "125cc/hour." The last is preferable for a maintenance IV because it is remotely possible that the physician intended to prescribe only the one liter and no more, whereas the "every 8 hours" and the hourly rate are open-ended.

You do have an infusion time and by doing simple division, an hourly rate.

1000 cc/ 8hrs = 125cc/hr.

x6hrs = 750cc

+ 100cc piggyback

= 850cc

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