Factors affecting the depth of the burn………

Doc, besides actually looking and evaluating the burn area is there other ways of knowing that the burn area might be deep?

Marjorie A, Sidney, Australia

A number of factors should be considered while evaluating the burn depth- temperature at which the burn is caused, duration of contact, cause of burn and site of burn.

The area which is burnt is also important as the skin thickness varies at different sites (from 1 mm in the genitalia and eyelids to 5 mm in palms and soles).  The skin is relatively thinner in children and geriatric patients and therefore they tend to suffer a greater degree of burns.

Contact burns tend to be deeper since the burning object or the hot object like the exhaust of a motorcycle remains in direct contact and causes more damage to the skin.

 It must be noted that the lesser the duration of the burn, the lesser the degree of burn. Therefore it is recommended that the burn area be cooled at the earliest. Pouring cold water over burns areas works on this principle and one must within seconds carry out this maneuver to avoid severe burns. The home kitchen is one area where burns often occur. Fortunately water is always available in the kitchen and therefore quickly pouring cold or tap water over the burn area works wonders and one should let the cold water run over the burn area for a few minutes.

Application of oil or mint preparations as is often done by lay people should be avoided as oil stops the heat loss from the surface causing more damage and mint just gives cools the mind and not the burn area.

The cause of the burn should be inquired into as different modes of burns can cause different depths of burns. For e.g. hot water burns are less deep than hot frying pan oils, as the temperatures of hot oil touch 175-200 degrees compared to hot water which may be 75-100 degrees. Different acids and bases can cause different degree of burns depending on their strengths. Thus knowing the burn agent helps a lot in deciding the depth of the burn and predicting the outcome.

 We shall discuss how the monitor burn patients in our next post....

(An original initiative in burn care and education from asktheburnsurgeon++)

Resuscitation Fluids and formulae……….

Doc, how much fluids should be given to a burn patient and can a person survive if fluids are given if the patient comes to the hospital many hours after the burn incident?

Shawn, California

As we discussed in an earlier post, burn wounds loose body fluids from the wound surface as the skin integrity is damaged. Greater the surface area of the burn, more the fluid loss. In general the body is able to tackle the fluid loss that occurs from a less than 15 percent TBSA (total burn surface area) in an adult, and less than 10 percent TBSA in a child. Beyond this the body’s internal mechanisms are unable to handle this loss and the patient will end up in shock if the lost body fluids are not replaced. Once we understand this concept then we are faced with two questions:

a) At what rate should we administer the intravenous fluids?

b) What is the type of fluid that we should administer?

Parkland formula

Charles Baxter from parkland hospital (Texas, USA) made a large contribution to the management of burns by his studies on the fluid loss in burns and their replacement. He observed that the first 24 hours were critical to the survival of burn patients and the replacement of fluids was to be done in the first 24 hours itself. In this the first 8 hours were crucial as the blood vessels and capillaries lost their integrity totally and therefore the intravascular fluids leaked out on a large scale. In the second 8 hours after the burn the capillaries regained their integrity and the leaks were controlled to a great extent. Keeping this in mind Charles Baxter suggested a fluid resuscitation formula in burn patients at 4 ml/kg/TBSA for the first 24 hours. The type of fluid suggested was Ringer Lactate.  Of the total fluid calculated for 24 hours, half of the volume was to be given in the first 8 hours and the rest in the next sixteen hours. 

Why did Baxter suggest Ringer Lactate as the resuscitation fluid?

  Obviously because he observed that it was more physiological and had many advantages:

a) Ringer lactate has a lower sodium concentration (130mEq/L) than normal saline. 
b)The metabolized lactate had a buffering effect on associated metabolic acidosis in burns. 
c)Ringer lactate is an Isotonic crystalloid solution
 

Example for fluid calculation:

Let’s take an example here – a patient with a body weight of 65 kg  comes to the ER with flame burns of 45 percent TBSA.

TBSA 45%

Weight of the patient- 65 kg

Therefore the fluid calculation by parkland formula-

4x% TBSA x body weight

i.e. 4 x 45 x 65

i.e.  11,700 ml for 24 hours

Half of this has to be given in the first 8 hours

i.e. half of 11,700 – which is 5850 ml for 8 hours

Therefore for each hour in the first 8 hours the patient needs 5850/8 ie 731.25 ml or approximately 730ml per hour

For the next 16 hours the remaining 11700 ml needs to be spread out

So 5850/16 is 365 ml needs to be given each hour for the next 16 hours

Thus the patient must receive 730 ml per hour for the first 8 hours post burn and for the remaining 16 hours of the first day the patient must receive 365 ml per hour. 

Coming to the second part of the question- the fluid calculated has to be replaced in the time specified. However some patients appear later than the time of the burn and therefore the fluids which were not administered will have to be replaced at a higher rate but taking care to see that we do not overload the patient and put him into cardiac failure or pulmonary edema.

It must be noted that the calculation of fluids by this formula is only a guide line and a number of factors must be taken into consideration which administering fluids which we shall discuss in another post …..

(An original initiative in burn care and education from asktheburnsurgeon++)

Classification of burns...........

Doc, are there different ways to classify burns?

Mrs. Janice Parker. S. Africa.

Yes there are different ways to classify burns, but the whole purpose is to help in managing them in a better way.  Every burn must be mentioned by its degree or depth since it lets the surgeon know whether he should manage the patient conservatively or by surgery. Further classifying burns in major, minor or moderate helps to decide the level of management that they need. Thus a third degree burn even if it is one percent TBSA (total burn surface area) cannot be managed conservatively and will need surgery. Again a 5 percent TBSA can be managed on an outpatient basis, but a 50 percent TBSA will definitely need inpatient management.

degree of burns.

Degree of burn actually tells us about the depth of the burn. The burn depth is classified as follows.

a) First degree- superficial burns affecting the epidermis are referred to as first degree burns and are similar to sunburns.

 b) Second degree: both the epidermis and the superficial layer of the dermis are damaged in second degree burns.

c) Third degree burns: these burns affect the full thickness skin and often needs surgical management.

d) Fourth degree burns: these burns affect the full thickness of the skin and the underlying structures like nerves, muscles, tendons, vessels and may extend up to the bone.

We can also classify burns according to their size:

a)Major Burns: these consist of chemical or high voltage electrical burns, Inhalation injury, full thickness burns more than 10% TBSA or burns involving more than 25%TBSA.

b) Moderate Burns: these consist of Superficial or partial thickness burns of trunk, hands, feet, perineum or head involving 15-25% TBSA.

c) Minor Burns:  these consist of Burns not involving the hand, perineum, feet or head and must be less than 15% TBSA.

(An original initiative in burn care and education from asktheburnsurgeon+)

ASSESSMENT OF BURN SURFACE AREA……

Doc, what happens if I calculate the burn area wrongly? Is it really important?

Arthur A, Canada

As we have seen in previous posts the loss of fluid from the skin surface depends on the degree of burns and the area of the burns. One must evaluate the total burn surface area (TBSA) to calculate the fluid requirements. There are different methods of fluid calculation in burns.

a) Rule of nine

The rule of nine works well in adult patients. In this method the body surface is divided into various parts measuring in nines.

Rule of nine

Each arm - 9% TBSA

Head - 9% TBSA

Anterior thorax - 18% TBSA

Posterior thorax - 18% TBSA

Perineum - 1% TBSA

Each leg - 18% TBSA

Any burn surgeon will tell you that more often the burns are so irregularly placed that accurate calculation becomes difficult in different regions of the body. In such cases a simple trick is to use the palm of the hand as a method of calculation. At any age the palm of the hand is approximately 1% and can be used to measure the burn areas.  One must not forget that it is the patient’s hand that is used for the calculation and not the doctor’s. An approximate size of the palm of the patient is considered and the equivalent burn area is estimated. For e.g. lets say the burn area was 5 palm sizes of the patient over the body and lower limbs. Now we can assume that the patient has about 5% burns.

It should be noted that first degree burns do not produce fluid losses and therefore only 2^nd degree burns or more should be used for fluid calculation.

However in children the rule of nine can lead to serious errors as the head and body is larger in TBSA than the limbs and therefore the Lund and Browder charts work out to be more accurate while calculating the fluids to be administered.  The Lund and Browder chart is shown below. 

If the fluid calculation is wrong then the patient will be administered less fluids and this will result in shock or low volume circulatory failure and ultimately may be fatal.  The fluids calculated need to be replaced within a time limit as we shall discuss in the next post. Correct volume replacement and correct timing is what makes the resuscitation of burns patients successful.

(an original initiative in burn care and education from asktheburnsurgeon+)

How burns affect the tissues.....

Doc, could you please explain the cellular and chemical processes that occur when the tissues are burnt?

Rony v, Goa

A number of inflammatory processes both local (at the site of the burn) as well as systemic (in the rest of the body) take place when burns occur which eventually lead to the shifting of fluid from the vascular compartment to the interstitial spaces. Subsequent to the burn a number of cells like Neutrophils, macrophages, and lymphocytes cross over into the burned tissues and start releasing chemical mediators like histamine, serotonin, prostaglandins, kinins, platelet products and complement components. These chemical substances damage the normal blood capillary barrier which leads to an increase in the permeability of the vessels. Intravascular fluids therefore start to leak from the walls of the vessels and this ultimately leads to a decrease of the circulating intravascular blood volume. A fact that is not commonly recognized is that these processes that occur in the burn tissues also take place in the tissues that have not suffered any burns and therefore one can see edema in areas of the body that have not suffered burns. Thermal injury also ends up damaging the cell wall and collagen fibers which in turn lead to inadequacy of the cell wall transport mechanisms and buildup of sodium and water and eventual death of the cell if the fluid imbalances are not immediately corrected. In minor burns such as 10 percent in children and about 15 percent in adults these fluid balances are well adjusted and tolerated and therefore additional fluid replacements are not needed. However in patients with TBSA higher than the one’s mentioned above intravenous fluid resuscitation is needed.

The capillaries begin to regain their functional integrity and the leak eventually gets controlled, but this often takes more than 8 hours post burn. Crystalloids are usually given in the first 8 hours and one’s the integrity of the capillary wall is regained after 8 hours, colloid fluids are started since they will not leak out. Adding colloids also help to reduce the fluid overload that may result of excess of crystalloid infusions. Burn wounds are composed of three zones- a central zone of coagulation or severe tissue damage, a peripheral zone of hyperemia or vasodilatation, and an  intervening zone of stasis or low blood flow (ischaemia). If the fluid imbalances that occur from the fluid shifts as noted above are not corrected on time then these zones can extend and more tissue damage can result explaining the fact that some superficial burns on admission can end up as deep over period of time. This can also happen when burn wounds get infected.

(an original initiative in burn care education from asktheburnsurgeon)

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