Welcome to the channel where medical topics are made easy.
Today we’re going to go over the Parkland formula for burns.
We’re also going to go through an example so you can practice.
The Parkland formula is good to know when caring for burn patients, and it commonly
shows up on medical and nursing exams.
You can find the notes, lecture, and study guide for the video on the website linked
down below.
All of the videos come with notes and written lectures, so make sure to hit that subscribe
button to not miss out on those.
Let’s look at the formula first, and then we’ll go over an example at the end.
The Parkland formula is used to calculate the initial fluid requirements in burn patients.
The Parkland formula for an adult is 4mLs times the body weight in kilograms times the
TBSA percentage affected by the burn.
This will give you the estimated total amount of fluids the patient should receive in the
first 24 hours after injury.
Half of that total volume should be given in the first 8 hours.
And the other half should be given over the next 16 hours.
It is important to remember the first 8 hours begins from the time of the burn injury, and
not from the time of presentation or when you made the calculation.
This means if someone presents to a hospital 2 hours after a burn, they should receive
the first half of their fluids within 6 hours instead of 8 hours.
So, the first half of their fluids may need to be administered at a faster rate due to
their delayed presentation.
We can see from the formula that there are 3 variables to look at.
Remember this equation is for adults, and we’re going to look at the formulas for
pediatrics later in the video.
First, we have the 4mL which is a constant.
The way I like to remember 4mLs is to use the word “for” in formula.
Next we have the patient’s body weight in kg, which is also easy to calculate.
Finally we have the TBSA percentage involved by the burn.
This helps determine the extent of the burn injury.
Only areas affected by partial thickness and full thickness burns, which are 2nd-degree
burns and higher, are counted toward the TBSA calculation.
Superficial, or 1st-degree burns, are not included in the calculation.
Determining the TBSA percentage will require calculating, and there are a few different
methods for doing this, so let’s take a look at them.
One of the more common methods for calculating the TBSA is the Rule of Nines.
We talked about the Rule of Nines in the previous video, so make sure to check that out if you
want to learn a simple way to calculate TBSA.
Basically the Rule of Nines provides a body surface area percentage for different body
parts as you can see in the table and diagram.
This can then be used in burn patients as a way to calculate the TBSA involved.
We’re going to look at an example at the end, and this will help you see how it works.
But it you need a quick refresher on the Rule of Nines, then make sure to watch the previous
video on it.
It’ll be linked down below in the description.
In addition to the Rule of Nines, there are a couple other methods you can use to calculate
the TBSA involved by a burn.
So the first method was the Rule of Nines as we just mentioned.
The problem with that as you might remember from the previous video on the Rule of Nines
is that the Rule of Nines is most accurate in non-obese adults, and it can be less accurate
in children.
Pediatric patients have disproportionately larger heads and shorter legs, which can make
the Rule of Nines less accurate as you can see in the diagram and table.
This table and diagram will give you approximate percentages for infants and young children.
These numbers will change in older pediatric patients.
We can see the head is disproportionately larger at 21% instead of 9%, and the legs
are disproportionately smaller at 13.5% each instead of 18% each.
This is where the Lund and Browder Chart comes into play.
The Lund and Browder Chart takes into account variations in body shape with age, and this
can be used in both adults and children to calculate TBSA.
You can see in the table how it takes into account the size of the head and legs based
on age.
The diagram shows you the constant percentages of the other body parts.
So you can see how the Lund and Browder chart can potentially provide a more accurate representation
of the extent of the burn, especially in children.
The downside compared to the Rule of Nines is it’s tougher to remember these numbers and
less efficient.
Another method is the hand or palmar method.
This method states the patient’s hand including their digits is approximately 0.8-1% BSA.
And the patient’s palm, not including their digits, is about 0.5% BSA.
Be careful as you might see some literature simplifying it and stating the palm alone
is about 1% BSA.
This has recently been shown to be a potential overestimation and that the palm is more accurately
about 0.5% BSA.
The hand or palmar method can be used in smaller burns.
But remember you're using the size of the patient’s own hand and not your own hand to approximate
the TBSA.
Now that the TBSA has been calculated,
we can figure out the total volume of fluids to be given in the first 24 hours after injury.
Early fluid resuscitation is important, especially in severe burn patients.
In addition to causing local damage to the skin and tissue, severe burns can generate
a systemic inflammatory response, which can affect the entire body.
During the inflammatory response, the capillaries can become more permeable, which means intravascular
fluid can leak into the interstitial space.
In other words, fluids within blood vessels can leak out into spaces outside the vasculature
where it doesn’t belong.
The capillary leak can result in large fluid shifts from the intravascular to the interstitial
space, which can cause intravascular volume depletion and edema.
The intravascular hypovolemia, or volume depletion, from fluid shifts can lead to decreased tissue perfusion.
The body will try to increase vascular resistance by constricting blood vessels in order to
maintain tissue perfusion.
The increased vascular resistance mixed with worsening hypovolemia can lead to worsening
tissue perfusion, known as “burn shock”.
Not to mention, cardiac output can also decrease from the hypovolemia.
Hypovolemia can decrease venous return to the heart, which can decrease stroke volume,
which can decrease cardiac output
So if you remember the different types of shock, we have a combination of distributive
shock from the capillary leak, hypovolemic shock from the fluid shifts and intravascular
fluid depletion, and cardiogenic shock from the decreased cardiac output.
The way to treat this is with aggressive fluid resuscitation with the goal to maintain tissue
perfusion and prevent end-organ damage.
Therefore, fluids play an important role in the management of circulation in severe burn
patients.
And this helps decrease morbidity and mortality.
So hopefully you can see now why fluids are so important and why there are formulas and
protocols to calculate fluid requirements, such as the Parkland formula.
The Parkland formula is one of the most well-known and widely used formulas to calculate initial
fluid requirements in severe burn patients.
Again, the Parkland formula for an adult is 4mLs times the body weight in kilograms times
the TBSA percentage affected by the burn.
This will give you the recommended amount of crystalloid fluids to be given over the
first 24 hours after injury
The first half of the volume is given in the first 8 hours after the burn, and the second
half is given over the next 16 hours.
The formula is used for partial thickness and full thickness burns
that are typically involving more than 20% TBSA in adults and greater than 10% TBSA in
children or the elderly.
Burns involving a TBSA less than that typically don’t cause massive fluid shifts and the
patient can usually tolerate fluids by mouth.
But that’s not to say the patient still won’t need IV fluids, and the Parkland formula
still may need to be used.
The Parkland formula can also be used in those with smaller burns but have injuries to the
mouth or inhalation injuries that would prevent them from tolerating fluids by mouth.
Those with heart failure, kidney disease, or other comorbidities that may affect fluid
resuscitation should have their volume status closely monitored.
While the Parkland formula is the most widely used, there are other formulas out there that
can help you calculate the recommended fluid volumes as well.
We’re not going to go into detail on these because the Parkland is the most well-known,
and it’s what commonly shows up on medical and board exams.
But this is just to make you aware that other formulas exist, and depending on where you’re
from, different parts of the world may have different institutional protocols.
Now that we know how to calculate fluids for adults, let’s look at the formula for
children.
The formula is the same with the exception of 3mLs instead of 4mLs.
So the formula is 3mLs times the body weight in kilograms times the TBSA percentage.
Children should also receive maintenance fluids in addition to their calculated fluid requirements.
The simple way to calculate maintenance fluids in pediatric patients is using the 4-2-1 rule.
The rule states to give 4mL/kg/hr of fluids for the first 10 kg of weight, 2mL/kg/hr for
the next 10 kg of weight, and 1mL/kg/hr for each kg of weight after that.
Other formulas for children besides the Parkland formula include the Shriners Cincinnati
and the Galveston formulas.
Again, these formulas are not the main focus of this video, but make sure to know what
your institution uses or recommends.
Let’s look at an example so we can see how the Parkland formula works.
The patient weighs 80 kg and has partial thickness burns involving the entire anterior trunk
and the entire anterior right arm.
Hit pause in the video and figure out the recommended fluids this patient should receive
in the first 24 hours using the Parkland formula.
Also figure out how much fluid should be given in the first 8 hours and over the next 16 hours.
First we have to calculate the TBSA, and we will use the Rule of Nines to do that.
We know the anterior trunk has a TBSA of 18%.
Next we have the burn involving the entire anterior right arm.
We know the entire right arm has a body surface area of 9%.
Since this burn only involves the anterior aspect, then it’s 4.5%.
So this patient with partial thickness burns to the anterior trunk and anterior right arm
has a TBSA of 22.5%.
Since this burn involves more than 20% TBSA of partial thickness burns, we can use the
Parkland formula.
We know the patient weighs 80 kg and has a TBSA percentage of 22.5, so we will multiple
4mLs by 80 by 22.5.
This will give us 7,200 mLs of fluid recommended within the first 24 hours.
Remember half of that, or 3,600 mLs, will be given over the first 8 hours, and the other
half or 3,600 mLs will be given over the next 16 hours.
Just a few points to wrap up the Parkland formula.
First, it's important to remember these formulas are guidelines and they're not hard-and-fast rules.
The Parkland formula may underestimate fluid requirements in some cases, especially inhalation
injuries, electrical burns, full thickness burns, and those who have delayed resuscitation.
The Parkland formula may also overestimate fluid requirements in other cases.
Under fluid resuscitation can lead to hypotension, poor tissue perfusion, acute kidney injury,
end-organ damage, among others.
Over resuscitation can lead to compartment syndromes, acute respiratory distress syndrome
or ARDS, among others.
Therefore, you will need to use your clinical judgement and monitor the patient’s fluid
status on a case by case basis.
For example, you can monitor hourly urine output through a Foley catheter, as well as
the patient’s vital signs, respiratory status, and mental status to name a few ways.
After 24 hours of fluid resuscitation, the Parkland formula, as well as other formulas,
will provide you with recommendations for the next 24 hours.
Hopefully this gave you a better understanding of burn management and fluid resuscitation.
If you found the video useful, please hit that like button and leave a comment.
Make sure to subscribe to not only catch future videos, but also all the videos come with
notes and study guides that you don’t want to miss out on.
The notes and study guide for this video are linked below.
Thanks for watching and hope you check out future videos.