testing tobramycin peak and troughs

[Guest guest]

Hi,

as I mentioned tobramycin levels in the last message, here is one

interesting message about that topic from Cystic-L.

Peace

Torsten

Seattle's CHMC is practicing a new method of testing

tobramycin peak and troughs during IV clean-outs. Instead of drawing

a trough 30 min before the dose, and a peak 30 min after the dose,

they are drawing a level 2 hr post-dose and a second level 4 hr post-

dose. These two

points are supposed to make a straight line (on semi-log paper, or

take the

log(10) of the raw data and use regular graph paper). The y-intercept

reveals the true peak, and the level at 7 and 1/2 hr post-dose

reveals the

trough. After the slope of this line is established, draws can be

done

anytime (though preferably between 2 and 4 hr post-dose) to determine

the

peaks and troughs during the course of the clean-out.

The purpose of this new method is to avoid the problems encountered

with

wildly fluctuating levels as a result of inaccurate draw times 30 min

post-dose. The labs don't like to be held down to a 1 or 2-min

window, and

there's quite a big difference in level if you give them a 5 min or

(as our

lab prefers) a *10* min window for draw times (i.e., 20 to 40 min

post-dose). This way, it doesn't matter very much *when* the draw is

performed, as long as the time of dose and draw are accurately

recorded and

reported to the pharmacist.

They're still working out the bugs, but it looks like a great

improvement on

the old system. It should reduce pokes - no trough is drawn at all -

without reducing safety, but we'll see. I'm anxious to see if this

is true of more patients -

it's the saftey issue that's most critical.

Are there any other clinics out there that use this method of tobra

level assay?