Question About Fluid Resuscitation with Burns

TBSA% Burned is 31%. The pt weighs 50 kg. The burn injuries occurred at 0300. Fluid resuscitation was started at 0400, and it is now 0900.
Calculate her fluid replacement for the first 24 hours, specify how much will be given, what time intervals will be used, and what the infusion pump should be set for (in mL/hr).
Pt burned at 0300 <GO BY THIS TIME WHEN CALCULATE (b/c go by the time of injury)
TBSA Burned = 31% Pt Weight = 50 kg
Started fluid resuscitation at 0400 (1 hr AFTER time of injury)
Time Now = 0900 (fluids going for 5 hrs)
4 mL x 50 kg x 31% = 6200 mL for 24 hrs
6200 mL/2 = 3100 mL
Pt gets 3100 mL in first 8 hrs
Pt gets 3100 mL in next 16 hrs
You have to adjust the formula to reflect initiation of fluids at the time of injury
Fluid resuscitation started at 0400 (1 hr after injury), it is now 0900. So, pt has received fluid resuscitation for 5 hrs. However, you need pt to have received it for 6 hours (time of injury was 0300 and you adjust formula to reflect initiation of fluids at time of injury. Time of injury (0300) to time now (0900) is 6 hours.
Time of Injury = 0300 Fluid Resuscitation Started = 0400 Time Now = 0900
So adjusting formula to reflect initiation of fluids at time of injury means that you adjust the formula to reflect that the fluid started at 0300 (even though it was really started an hour later at 0400)??? Is that correct?
So the time of injury was 0300 and it is not 0900, so the adjusted time of fluid resuscitation would be 6 hrs (0300 to 0900 = 6 hrs)
Started at 0400 (1 hr after burn injury), now 0900 – Received for 5 hrs (need it for 6 hrs because adjust formula to reflect initiation of fluids at time of injury, which was 0300, and 0300 to 0900 = 6 hours).
From here, I know what to do, but I'm not sure I am correct in the reasoning.
To calculate mL/hr for the first 8 hrs, you need to divide by 7 (instead of 8) because the fluid resuscitation should begin at the time of injury (0300) but began an hr later at 0400, so the pt missed an hr. You need to account for that missed hr. You do this by dividing by 7 instead of 8 (b/c pt should receive the first half of the total 24 hours of fluid resuscitation (i.e., 3100 mL) in the first 8 hrs. If the fluids were started an hr after the time of injury, that means the fluids were started an hr late, so instead of running for 8 hrs, they will run for 7 hrs – this is b/c if the starting of fluids is delayed, then the same amount of fluid is given over the remaining time – in this case, the start of fluids was delayed 1 hr (burned at 0300, started fluid resuscitation at 0400), so the remaining time is 7 hrs (8 hrs – 1 hr delayed = 7 hrs).
So, is my reasoning correct?
Do you subtract the missed hr from total hrs? I know that the pt needs to get the first half in the first 8 hrs after the injury, so if they miss an hr, then you need to adjust for that. If an hr was missed, you run the fluids over 7 hours so that the pt gets the required amount of fluid within 8 hrs from the time of injury. Is this because the pt will get more fluid per hr running it over 7 hrs, which makes up for the missed hr?
3100 mL/7 hrs = 442.9 mL/hr for the 7 hrs.
To calculate mL/hr for next 16 hrs, you divide 3100 by 16 hrs.
3100 mL/16 hrs = 193.8 mL/hr for the next 16 hrs.
Okay I know this is long, but I hope you stick with me!!
I just want to know if my reasoning is correct as to why the time is adjusted. If the fluids are started an hr AFTER the time of injury, you adjust the time to receive the first half of fluids to 7 hrs. So I want to know if this is because the pt needs to receive the first half of required fluids within 8 hrs from the time of injury. Also, is it because the pt will get more fluid per hr running it over 7 hrs, which makes up for the missed hr?
As always, your time and responses are appreciated!! Thank you! 
Nov 6Based on your calculations that the parient should have received 3100 mL in the first 8 hours but were started an hour late, they should have been starred at 442.9 mL/hour, which you calculated. If now, 6 hours post injury you need to adjust the rate calculate the total volume received and subtract that from 3100 and run the remainder over the remaining two hours.
Ues, the calculate fluid volume is infused in the first eight hours because the fluid loss occurs beginning at the time of injury. 
Nov 6Thanks for your response!
What do you mean if now, 6 hrs post injury, you need to adjust the rate calculate the total volume received and subtract that from 3100 and run the remainder over the remaining 2 hrs?
Do you mean that you would take 3100/7 = 442.9 then take 442.9 x 6 hrs = 2,657.4 mL, so then you take 3100  2657.4 = 442.6 mL, so 442.6 mL needs to run over the remaining 2 hrs = 442.6/2 = 221.3 mL/hr? 
Nov 6Quote from KrCmommy522I might have misread your post, but it seemed you were talking about adjusting the rate mid infusion.[...]
Do you mean that you would take 3100/7 = 442.9 then take 442.9 x 6 hrs = 2,657.4 mL, so then you take 3100  2657.4 = 442.6 mL, so 442.6 mL needs to run over the remaining 2 hrs = 442.6/2 = 221.3 mL/hr?
When you use this formula, half of the calculated volume infuses in the first 8 hours, from the time of injury. In your scenario, if the fluids were initiated at the time of injury, the infusion rate would be 387.5 mL/hour. As they were started 1 hour post injury the 3100 mL needs to infuse at 442.9 mL/hour. If they were started 2 hours poadd t injury, the 3100 would need to infuse at 516.7 mL/hour. If the infusion is started at the appropriate rate, it shouldn't need to be adjusted.
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: (3100600)÷5, or 500 mL/hour. Of the infusion were stsrted too fast, you would also use this method to calculate the new, decreased rate.
I apologize for any confusion or lack of clarity in my previous post. 
Nov 6No problem! I just appreciate your response!!
Ok, so I get what you are saying. My only question is that in your example of the pt receiving the wrong rate at 300 mL/hr and arriving to the hospital 3 hrs post injury. Wouldn't he have received 900 mL of fluid (300 mL/hr x 3 hrs) as opposed to the original calculation of 442.9 mL hr, he should have received 1328.7 mL; resulting in a deficit of 428.7 mL. The remaining time is 5 (since he arrived 3 hrs post injury), so (3100  428.7)/5 = 2671.3/5 = 534.3 mL/hr?
Sorry I keep asking questions! But thank you so much for helping me understand this more!! 
Nov 6No, I used your original scenario where the fluids were started 1 hour post injury.
I think you get this. Always remember these two points when calculating fluid replacement for burn patients. The first is that the patient receives half of the calculated volume in the first 8 hours, based upon the time of injury. Second, when you receive the patient you need to determine how much fluid he has received and calculate the remaing volume so that you verify that at the current infusion rate he will receive the correct volume of fluid replacement. 
Nov 6I understood you were using my example, but when you went further to say that if the infusion had been started either too fast or too slow:
Quote from chareI think I misunderstood a part of it. So, when you say that if the infusion was started at 300 mL/hr 1 hr post injury, and the pt arrives to the hospital 3 hrs post injury, then the pt would have been receiving the fluids for 2 hrs (not 3, since fluids were started 1 hr post injury). So, the pt would have received a total of 600 mL of fluids (300 mL/hr x 2 hrs).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: (3100600)÷5, or 500 mL/hour. Of the infusion were stsrted too fast, you would also use this method to calculate the new, decreased rate.
Now, if the fluids had been running at the correct rate of 442.9 mL/hr, the pt should have received 1328.7 mL (the pt arrived 3 hrs post injury, so at a rate of 442.9 mL/hr x 3 hrs = 1328.7 mL). However, fluids were running at 300 mL/hr and were started an hr late, so pt only received 600 mL, which results in a deficit of 728.7 mL. The remaining time is 5 hrs (because arrived 5 hrs post injury), so (3100  728.7)/5 = 2371.3/5 = 474.26 = 474.3 mL/hr.
So, I think I understood what you were saying  other than the part where you said the fluids were started an hr after the injury (like in my problem) but were running at 300 mL/hr and the pt arrived to the hospital 3 hrs postinjury  I was using 3 hrs for how long the wrong rate of 300 mL/hr was running, when I needed to use the time the fluids were started, which was an hr late, so 2 hrs needed to be used.
I'm just confused as to where you get the pt should have received 1162.5 mL. If the fluids were running at 442.9 mL/hr for 3 hrs, the pt should have received 1328.7? Correct?
Again, sorry if I'm being a pain! I just want to fully understand this! 
Nov 7Quote from KrCmommy522The way I read this problem is thatTBSA% Burned is 31%. The pt weighs 50 kg. The burn injuries occurred at 0300. Fluid resuscitation was started at 0400, and it is now 0900.
Calculate her fluid replacement for the first 24 hours, specify how much will be given, what time intervals will be used, and what the infusion pump should be set for (in mL/hr).
Pt burned at 0300 <GO BY THIS TIME WHEN CALCULATE (b/c go by the time of injury)
TBSA Burned = 31% Pt Weight = 50 kg
Started fluid resuscitation at 0400 (1 hr AFTER time of injury)
Time Now = 0900 (fluids going for 5 hrs)
4 mL x 50 kg x 31% = 6200 mL for 24 hrs
6200 mL/2 = 3100 mL
Pt gets 3100 mL in first 8 hrs
Pt gets 3100 mL in next 16 hrs
You have to adjust the formula to reflect initiation of fluids at the time of injury
3100mL should be given within the first 8hrs (03001100)
It is now 0900 and the rate needs to be adjusted
04000900 @ 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 (09001100),
so 31001937.5mL 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 postinjury(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 postinjury?"
P.S. I haven't gotten this far in NS yet, is the 4mL x weight x %bsa burned a standard formula?Last edit by student_B on Nov 7 : Reason: clarifying my math a bit 
Nov 7All right....I am totally confused now!!
Quote from student_BBut 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 (03001100)
It is now 0900 and the rate needs to be adjusted
04000900 @ 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 (09001100),
so 31001937.5mL 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 postinjury(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 postinjury?"
Quote from chareBased 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: (3100600)÷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!! 

Nov 8Quote from KrCmommy522No, not all. I haven't had opportunity to post. Hopefully tomorrow I can answer some of your questions.I guess I got too annoying in my persistence/confusion

Nov 9Ok! Great! Just thought maybe I scared you away because I definitely know my persistance can be annoying! No rush! Just happy I didn't scare you away!

Nov 10Quote from KrCmommy522I think this is where some of the confusion arises. The Parkland formula, which you are using, estimates the fluid resuscitation requirements for burn patients, during the first 24 hour period, starting at the time of the injury. This primarily affects the infusion rate for the first half of the calculated volume.[…]
Pt gets 3100 mL in first 8 hrs
Pt gets 3100 mL in next 16 hrs
You have to adjust the formula to reflect initiation of fluids at the time of injury
[…]
Started at 0400 (1 hr after burn injury), now 0900 – Received for 5 hrs (need it for 6 hrs because adjust formula to reflect initiation of fluids at time of injury, which was 0300, and 0300 to 0900 = 6 hours).
[…]
Let's use the patient you describe in your initial post, who should receive 3100 mL during the first 8 hours. If the infusion is started at 0300, the time of injury, which is unlikely, it would infuse over 8 hours, or 387.5 mL/hour. If the infusion is started at 0400, or 1 hour post injury, it would infuse over 7 hours, or 442.9 mL/hour. If the infusion started at 0500, or 2 hours post injury, it would infuse over 6 hours, or 516.7 mL/hour. You would continue this, depending upon what time the infusion was started.
Two key points that you always need to remember are:
1. What is the volume that you need to infuse?
2. How much time is left in the initial 8 hour period from the time that the infusion is started.Quote from KrCmommy522Again, I think this is where a lot of confusion arises. The time of injury is only important in determining the end time of the initial 8 hour period post injury. Once you have determined these, the time of injury is not important. The infusion rate of the first 3100 mL is based upon how much time remains in the 8 hour period from the start of the infusion.[…]
[/B]To calculate mL/hr for the first 8 hrs, you need to divide by 7 (instead of 8) because the fluid resuscitation should begin at the time of injury (0300) but began an hr later at 0400, so the pt missed an hr. You need to account for that missed hr. You do this by dividing by 7 instead of 8 [B](b/c pt should receive the first half of the total 24 hours of fluid resuscitation (i.e., 3100 mL) in the first 8 hrs. If the fluids were started an hr after the time of injury, that means the fluids were started an hr late, so instead of running for 8 hrs, they will run for 7 hrs – this is b/c if the starting of fluids is delayed, then the same amount of fluid is given over the remaining time – in this case, the start of fluids was delayed 1 hr (burned at 0300, started fluid resuscitation at 0400), so the remaining time is 7 hrs (8 hrs – 1 hr delayed = 7 hrs).
[…]
Quote from KrCmommy522Again, once you have determined the ending time for the initial 8 time period forget the time of injury and base all of your calculation on the time remaining until the end of the first 8 hour time period. The infusion rate for the second half of the calculated volume should not be affected.[…]
Do you subtract the missed hr from total hrs? I know that the pt needs to get the first half in the first 8 hrs after the injury, so if they miss an hr, then you need to adjust for that. If an hr was missed, you run the fluids over 7 hours so that the pt gets the required amount of fluid within 8 hrs from the time of injury. Is this because the pt will get more fluid per hr running it over 7 hrs, which makes up for the missed hr?
[…]
[QUOTE=KrCmommy522;9632147]Thanks for your response!
Again, I apologize for my post regarding having to adjust the infusion rate, but thought you were asking that in your initial post. Having done so, let me clarify.
If you were to receive this patient in transfer, you need to ensure that the fluids were administered at the correct rate. To do this, you need to know three things:
1. How much fluid should the patient receive during the first 8 hour period?
2. How much fluid has he received?
3. How much time is remaining until the end of the first 8 hour period?
Again, let's consider the patient in your initial post. You receive him in transfer from another facility at 0600, three hours post injury. His calculated fluid replacement requirement for the first 8 hours is 3100 mL. If his fluids were initiated at 0400 at a rate of 442.9 mL, he would have received 885.8 mL. As you have 5 hours remaining, he will receive an additional 2214.5 mL of fluid, for a total of 3100.3 mL, exactly what he should have received.
If on the other hand, the infusion had been started at 0400 at 300 mL/hour, when you receive the patient at 0600 he would have received 600 mL. If you continue the infusion at 300 mL/hour for the remaining 5 hours he will receive an additional 1500 mL, for a total volume of 2100 mL; this leaves a deficit of 1000 mL. To adjust the rate, subtract eh 600 mL that he has already received from the 3100 mL that he should receive during the first 8 hours. Doing so demonstrates that the patient needs to received 2500 mL in the next 5 hours to receive the total calculated volume, of 500 mL/hour.
I know that I'm starting to sound like a broken record with this, but these are the key points that should be remembered.
1. The time of the injury is only important in calculating the time for the initial 8 hour period.
How much fluid should the patient receive during the first 8 hour period?
2. How much time is remaining until the end of the first 8 hour period?
In addition, if you receive the patient in transfer,
1. How much fluid has he received?
At the current infusion rate, how much fluid will the patient receive in the time remaining in the initial 8 hour period?
2. When you combine both volumes, will the patient have received the total calculated volume for the initial 8 hour period?
You might find the Medscape (requires free registration to access) Burn Resuscitation and Early Management article helpful.