Posted by isntshelovlei on March 24, 2010
So we had a dimensional analysis quiz last night. Ah yes, the dreaded med math—what some nursing students have nightmares about. Every semester we have quizzes on drug calculations. In my program we have to get a 90% or higher on them—at some schools it’s 100%—or you will fail the clinical portion of the course (which means you’ll just fail the course—you can’t fail clinical and pass lecture). Hence why many students get their panties (or boxers/briefs) all up in a bunch. I’m not sure what the old-school method was, but dimensional analysis is really quite simple. The biggest challenge is remembering all of the conversion factors. Some are well-known such as 1000 mg = 1 g, whereas some like 1 gr = 60 mg (what the heck is a grain anyway?) are a little less so. But once you have the conversions factors under your belt, it’s pretty much all downhill from there.
Let’s look at an example. Let’s say the physician has ordered a patient to receive Erythromycin 150 mg PO TID. The pharmacy sends the medication in a bottle labeled 0.75 g per fluid ounce. How many ml should be given at each dose?
I always like to start with the amount ordered (150 mg). Next I look at the dose on hand (as if the pharmacy could ever send it to you the way you actually need it), which is 0.75 g per fluid ounce. The monkeywrench is that I need to administer the medication in milliliters. So I’ll need two conversion factors to make this work—1 gram = 1000 mg and 30 ml = 1 ounce. If you set up the problem correctly the unnecessary measurements will cancel out and you’ll be left with what you need—milliliters. Keep in mind that the conversion factors can always be flipped so that the unwanted measurements cancel out properly—notice how I wrote 1 oz / 0.75 g instead of 0.75 g / 1 oz. Once you have it all lined up, multiply across the top, multiply across the bottom, simplify, and voilà! Piece of cake.
There are a few miscellaneous rules to remember with med math. For instance, always use leading zeros and never use trailing zeros. This helps to reduce possible medication errors. People’s handwriting often sucks and so if a nurse transcribes an order into the MAR for 1.0 grams of a medication but the next nurse doesn’t see the barely-there decimal sign and misinterprets it as 10 grams—she just gave your patient ten times the medication they were supposed to get. Same thing with leading zeros—.1 g can be misinterpreted as 1g. Watch those zeros! Rounding answers can also be tricky. In general, you’ll want to round to a whole number when your measurement is a capsule, gelcap, unscored tablet, etc. Nothing like trying to administer 0.92 of a tablet to a patient…
Posted in Nursing school | Tagged: amount ordered, conversion, dimensional analysis, dose on hand, drug calculation, errors, factor, leading, math, med math, medication, Nursing, Nursing school, nursing student, pharmacy, quantity, quiz, tablet, trailing, zeros | 1 Comment »
Posted by isntshelovlei on October 8, 2009
We finally had the dreaded “math/drug calculation exam”—the one you need to get an A on or fail the course (though they do give you 3 tries before they cut you loose). I’ve always heard nursing students making such a big deal out of this exam, claiming to have lost sleep (and even hair) over it. It did take memorizing some of the lesser known conversions like 1 grain = 60 milligrams and 30 milliliters = 1 ounce, but it really wasn’t that bad. Aced it—100%. I think a lot of the stress nursing students experience comes from all of the melodrama and sensationalism they attach to everything. Chillax already—when one of us gets all worked up about something it is contagious—it spreads through the class faster than a fire in a grease pit. Not that I don’t have my own fair share of stress and worry, but the level of agitation among some of these students gives me flashbacks of my days working in inpatient psych—sheesh.
The other big kahuna (at least for a first semester nursing student) was skills testing. You basically rotate through several “stations” and demonstrate each skill. You have to get at least a 75 on each one or you have to return for remediation (*enter scary music*). So for the past six weeks we have been in the lab learning skills—vital signs, injections, catheter insertion, wound care…among other things. The lab was then available for “open lab” for those who wanted to practice before the actual testing. After one open lab it became evident that different groups were learning different techniques, some of them outrageously (and dangerously) as the Grinch would say—WRONG-O! I saw one student do a Z-track by making an actual Z with the needle as she withdrew it—what in the world?!? You’re supposed to withdraw the needle at the same angle it was inserted (straight out)…I wonder how many degrees a “Z” angle would be…
The actual testing went well. Got there early, but of course they were running behind schedule. Students were in the hallway trying to cram last-minute bits of information into their already encumbered semantic memories (“what’s systolic pressure again?”…). Finally it was my turn. First up was the Foley, which I was to insert into a female manikin (no live volunteers for this one, LOL). So the big issue with catheter insertion is not breaking the sterile field. But I was fine, took my time and talked my way through it. Next up was vital signs which were a no-brainer, then medication administration/injections. I had to select the appropriate needle and injection site (though she made me name all of them anyway). I was given an “order” to mix 10 units of regular insulin with 20 units of NPH. No problem, thanks to the mnemonic “Nancy Regan, RN.” So after all of the default stuff (5 rights, etc.), I draw up 30 units of air, inject 20 into the airspace of the NPH, then 10 units into the Regular, invert the vial, draw 10 units of Regular, then go back and draw 20 units of NPH—piece of cake right? I give my imaginary patient a 90° injection (instead of a 45° since my 85-yr-old “patient” is very thin) into her imaginary abdomen (which is actually a square pad of something nasty and gel-like, filled with the millions of injections it had received before mine). Meanwhile, the tester is firing questions at me, but at this point I’m like “Bam–ok, what else you got?” My last station was wound care—remove the dressing, measure the wound, irrigate, culture, and redress. It was a medical asepsis and not a sterile procedure so I didn’t have to worry about breaking any fields (just changing my gloves fifty times). Once you pass through all the stations the tester tallies up your grade, you sign off on it, and they send you on your merry (or unmerry for some) way.
After it was finally over and I emerged from the lab unscathed as opposed to running from the room crying and screaming with my hair on fire, there were about 5 students still anxiously waiting in the hall all staring at me with this look on their faces—“Well?!? Did you pass?” Of course I did, no sweat…
Posted in Nursing school | Tagged: catheter, drug calculation, Foley, injections, lab, Nursing, Nursing school, nursing student, remediation, RN, vital signs, wound care, Z-track | 2 Comments »