Estimation of Total Body Surface Area (TBSA) & Calculation of Volume Resuscitation

by Julianna Jung, MD, FACEP

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    00:01 How do we assess the surface area? There’s lots of different ways of doing it.

    00:04 One commonly used one is the rule of nines which is really only valid for adults and that basically says that the head is 9%, the front of the torso is 9, the back of the torso’s another 9.

    00:16 The front of the abdomen’s 9, the back of the lower back is another 9.

    00:21 Each leg is 18, each arm is 9, it all adds up to a hundred but it’s actually not terribly reliable even though it is easy to remember especially at extremes of weight.

    00:31 So very thin patients or very obese patients, this doesn’t really give you a good accurate assessment and there is a pediatric version available but because these proportions are so growth dependent, it’s not actually as accurate as we might hope.

    00:47 So a little bit more sophisticated approach is the Lund-Browder Chart.

    00:51 This is not one that you’re gonna be able to memorize.

    00:54 So you would definitely have to pull this up and refer to it while you’re calculating surface area.

    00:59 It’s definitely more complex than the rule of nines but it does address issues of relative growth for pediatric patients.

    01:06 So it shows you visually how the body is broken down and then, it actually provides you with a chart based on the patient’s age that tells you, yeah, if you’ve got half the head involved and it’s a baby, it’s gonna be 9.5%, whereas if it’s a 15 year old, it’s gonna be 4.5%.

    01:25 So it addresses the relative sizes of different body parts and different age ranges, and allows you to more accurately calculate the total percent burned.

    01:34 The most commonly used one is the Parkland formula.

    01:37 It’s based on lactated ringers and the calculation is 4cc per kilo per percent surface area burned.

    01:46 You give half of that in the first 8 hours, and then, the other half over the next 16 hours.

    01:52 Now, there have been a lot of studies looking at the Parkland formula and it actually results in over-resuscitation in a significant percentage of patients.

    02:00 So you wanna be a little bit careful and make sure that you’re monitoring and titrating the patient’s fluid intake to their urine output.

    02:10 A lot of times, people use the Modified Brooke formula which as you can see, is a little bit less aggressive.

    02:15 It’s 2cc per kilo per percent burned for adults and 3% for children.

    02:21 So it’s a little bit less than what Parkland gives Current Advanced trauma, life support and the American Bar Association guidelines both endorse the use of the modified Brooke formula.

    02:32 However, the overall goal of fluid resuscitation is to titrate fluid input to urine output goals.

    02:39 but in either case again, you wanna make sure that you’re carefully monitoring urine output.

    02:44 We expect half a cc per kilo per hour for adults and between half a cc and one cc per kilo per hour for children.

    02:53 If you’re getting significantly more urine output than that, you’re probably over resuscitating and wanna back off on your fluids a little bit.

    03:00 So just adjust it so that you maintain the expected urine output over time.

    03:05 So here’s an example just to go through the calculations for you.

    03:08 We’ve got a 29-year-old man who got drunk and fell into a campfire.

    03:12 He’s got burns over his entire anterior chest and abdomen, as well as his bilateral thighs, which gives us a roughly 27% total body surface area burn.

    03:24 His weight is 80 kilos.

    03:26 So by the Parkland formula, 4 cc per kilo times 80 kilos, times 27% burned gives us 8640 cc of lactated ringers.

    03:40 Now, Parkland tells us to divide that in half.

    03:42 We’re gonna give half of that in the first 8 hours.

    03:45 So 4320 cc over 8 hours which is 540 cc an hour.

    03:50 That’s a lot of fluid, right? That’s more than half a liter of fluid per hour.

    03:55 So it’s a pretty significant volume.

    03:56 The remainder, we’re gonna give in the next 16 hours and that’s gonna take us down to 270 cc per hour after the first 8 hours of resuscitation.

    04:05 So let’s say our patient has 300 cc of urine output in a 2-hour period.

    04:12 Well, he’s an 80 kilo guy, so we expect him to have half a cc per kilo per hour, or about 40 cc an hour.

    04:21 He’s had 300 cc in 2 hours which is more than three times what we’d expect for him.

    04:26 So this is a situation where we would wanna say, okay, we’ve gotten a little bit overzealous with our fluid.

    04:32 Let’s back it down.

    04:33 Let’s maybe cut it in half and reassess the urine output in a couple of hours to keep ourselves on track.

    About the Lecture

    The lecture Estimation of Total Body Surface Area (TBSA) & Calculation of Volume Resuscitation by Julianna Jung, MD, FACEP is from the course Toxicologic and Environmental Emergencies. It contains the following chapters:

    • Estimation of TBSA
    • Calculation of Volume Resuscitation

    Included Quiz Questions

    1. 1.5%
    2. 1%
    3. 2%
    4. 2.5%
    5. 3%
    1. 2cc / kg / %TBSA
    2. 3cc / kg / %TBSA
    3. 4cc / kg / %TBSA
    4. 1cc / kg / %TBSA
    5. 0.5cc / kg / hr

    Author of lecture Estimation of Total Body Surface Area (TBSA) & Calculation of Volume Resuscitation

     Julianna Jung, MD, FACEP

    Julianna Jung, MD, FACEP

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