i was a surgical nurse for many years and worked on a unit where we had postop turps and cystos with continuous bladder irrigations running. i know exactly what you are talking about.
"credit", by definition, is the amount of anything you have. so when you were told at morning report that the patient had "a credit of 1000ml
" it meant that you had
1000 ml of irrigation solution that was hanging and ready to be used. many times these bottles hold 1500 or 2000 mls of the irrigating solution. the nurse was telling you that she was leaving 1000 mls of the solution for you to use to irrigate your patient's bladder. we used to call these things through-and-through irrigations, or t&ts, because the sterile water went through the catheter, into the bladder, right back out the catheter and into the foley bag. when that 1000 ml goes into the bladder as input, it must also be subtracted from the foley bag contents because it is not urine output.
so, each time you empty the foley drainage bag, you need to determine how much is irrigating fluid and how much is actually urine. that is done by subtracting out the amount of irrigating fluid that was used. to do that you will also take a measurement of how much irrigating solution is remaining in the bottle at the time you empty the foley drainage bag
. we used to mark the fluid level on the containers with a magic marker or a piece of tape. that becomes your new "credit" amount
. to get the output measurement you take your old "credit" amount
(ex: the 1000 ml you were left with) and subtract the new "credit" amount
. that is the amount of irrigation solution that will be in the foley drainage bag. take that amount and subtract it from the amount you emptied from the foley drainage bag
and that is the patient's true urine output. do this each time you empty the foley drainage bag.
these can get hairy because some of these irrigations can be running very fast. if that is the case, keep on top of them, empty them frequently and do the calculations with each emptying. our surgeons instructed us to run the irrigant fast enough to keep the urine a light salmon color, so we sometimes ran 10,000 ml of irrigant a shift. if we didn't bad things happened. output should always be more than input. it is important to know that normal urine output should be around 30 ml/hour.