All right....I am totally confused now!!
Quote from student_B
But the fluids adjusted for being started an hr late was what my OP was? The fluids being started an hr late, made it so the rate needed to be 442.9 mL/hr over 7 hrs.
The way I read this problem is that
-3100mL should be given within the first 8hrs (0300-1100)
-It is now 0900 and the rate needs to be adjusted
-0400-0900 @ 3100mL/8hr ordered rate = 387.5mL/hr x 5hrs infusion = 1937.5mL infused so far.
the remainder of the 3100mL must complete in next 2hrs (0900-1100),
so 3100-1937.5mL leaves 1162.5mL to infuse over 2hrs.
1162.5mL/2hrs = 581.25mL/hr. Therefore, now (0900) you set the pump to infuse at 581mL/hr (or 581.2 or 581.3 depending on rounding policy) to infuse the remainder of the 3100mL within 8hrs post-injury(1100).
Then, at 1100 set the pump at 193.75mL/hr (3100mL/16hrs) to finish the order.
Very similar to your OP, except in the OP the rate is adjusted at 0400 (1hr post injury) whereas I read the question as "its been infusing at the 8hr rate, but was started 1hr late and has been going for 5hrs, how do you adjust the rate to ensure the 3100mL completes 8hr post-injury?"
Quote from chare
Based on your calculations student_B – which seem to match up mostly with what Chare said
If, on the other hand, the infusion is started either too fast or too slow, when you receive the patient you will need to adjust the rate. For example, I'll use your patient, that should receive 3100 mL in the first 8 hours. If the infusion were started 1 hour post injury at 300 mL/hour as opposed to the calculated 442.9 mL/hour and arrives at your facility 3 hours post injury. He has received a total of 600 mL fluid. Based upon your initial calculations, and if the fluids were started at the time of injury, he should have received 1162.5; resulting in a degicit of 562.5 mL. In this situation you would need to adjust the rate to ensure that the patient receives the total calculated replacement fluid. To do this subtract the volume delivered from the calculated volume, and deliver the remainder over the remaining time, or: (3100-600)÷5, or 500 mL/hour.
Your calculating the infusion being started on time, dividing by 8 hrs, but the infusion was started an hr late.
If they were started an hr late, you would need to adjust the formula to reflect initiation of fluids at the time of injury
(0300), which was where I got the 442.9 mL/hr.
If you do the formula as if the pt received the fluids an hr late, but divide by 8 hrs, then you get 387.5 mL/hr and when you multiply that by the 5 hrs they've been running (0400 to 0900), you get 1937.5 mL infused.
3100 mL needs to infused in 8 hrs, so you take 3100 mL pt needs total – 1937.5 that was infused already and get 1162.5 mL (so now I know where that came from in Chare's calculations
). - But again, I don't get why you're dividing by 8 hrs, since fluids were started an hr late??
There are 2 hrs remaining in the first 8 hrs, so the remaining 1162.5 mL needs to run over 2 hrs = 1162.5/2 = 581.25 = 581.3 mL/hr over the next 2 hrs.
Except in Chare's calculations, she does (3100 – 600)/5 = 2500/5 = 500 mL/hr
So, Student_B, your calculations match up with Chare's up until the end –
So, both of you calculated the rate as if the fluids were started at the time of injury and did 3100/8 – 387.5 mL/hr. But since they were started an hr late, shouldn't it be 3100/7 = 442.9 mL/hr. Since, like I said in my OP, you have to adjust the formula to reflect initiation of fluids at the time of injury, which was 0300.
However, Chare's final calcuation takes the 3100 mL the pt needs to receive in 8 hrs, subtracts the 600 mL total the pt received at the incorrect rate of 300 mL/hr for 2 hrs, and then divides by 5 hrs (the amount of time the pt started receiving fluids (0400) to the time now at 0900)
So, I am totally lost!!!
If, as in my OP, the pt was burned at 0300
and fluids were started an hr late at 0400
, and it is now 0900
(fluids have been going for 5 hrs
The pt needs to get 3100 mL in the first 8 hrs
Since fluids were started an hr late, instead of taking 3100/8, you take 3100/7 (you divide by 7 to make up for the hr that was missed).
3100 mL/7 hrs = 442.9 mL/hr given for the first 7 hours (again, given for 7 hrs because fluids were started an hr late).
So, fluids going at the adjusted rate of 442.9 mL/hr from the time of injury
(0300) to the time now (0900) – 6 hrs – would be 442.9 mL/hr x 6 hrs = 2657.4 mL total
But does that matter, because fluids were started an hr late, at 0400, and were started at the wrong rate of 300 mL/hr and ran for 2 hrs until the pt arrived at the hospital 3 hours post injury. So, pt hasn't really received that much.
Fluids being started an hr post injury and running for 2 hrs at the incorrect rate of 300 mL/hr means the pt received 600 mL/hr.
When pt arrived at the hospital 3 hrs post injury, I ASSUME, the fluid rate was changed to the correct adjusted rate of 442.9 mL/hr?
If pt arrived 3 hrs post injury, that would be 0600. So if fluids were running from 0600 to 0900 that is 3 hrs. If running at the adjusted rate that would be 442.9 mL/hr x 3 hrs = 1328.7 mL total.
600 mL infused at wrong rate + 1328.7 mL infused at adjusted rate = 1928.7 mL infused total.
(so pt received 1928.7 mL total from time fluids were started at 0400 to time now at 0900)
Pt needs 3100 mL total in the first 8 hrs.
3100 mL - 1928.7 mL = 1171.3 mL still left to infuse
Pt burned at 0300 and it's 0900 (6 hrs), so there are 2 hrs remaining in the first 8 hrs
To infuse 1171.3 mL in the remaining 2 hours
: 1171.3 mL/2 hrs = 585.65 = 585.7 mL/hr
So, the remaining 1171.3 mL needs to run at 585.7 mL/hr for the next 2 hrs in order for pt to receive the 3100 mL total in the first 8 hrs.
Where I am going wrong with this??
If fluids are started at the wrong rate and an hr late, do we not adjust the formula by adjusting the time to 7 hrs and divide by 7 still?
I know I am nagging and annoying! I'm sorry! I just really want to understand this! Thank you so much for all your help!!
student_B - Our instructor gave us the Parkland formula as:
(2 - 4 mL) x (wt in kg) x (TBSA%)
First half infused in first 8 hrs from time burn injury
Second half infused in next 16 hrs.
(Time starts from the time pt was injured!!)
But, the only way I've ever seen it and the only way she ever had us use it was 4 mL:
4 mL x (wt in kg) x (TBSA%)
First half infused in first 8 hrs from time of burn injury
Second half infused in next 16 hrs
You'll have to go by what your textbook/instructor says. But generally it seems to be 4 mL, not 2 - 4 mL.
Thanks for your help! Good luck with NS!!