By the term line of demarcation probably you mean the depth. Degrees in burns depends on the tissue depth involved which in turn depends on the nature of burns - thermal (including scald), chemical, electrical or radiation. In first degree, only the epidermis is involved and is evident as erythema or redness only and associated pain. Heals without any scar. Second degree burns is divided into superficial and deep. In second degree superficial, the superficial layer of the dermis I.e the papillary layer is involved and has erythema, edema, blisters or blebs and severe pain. Heals with minimal scarring. Second degree deep burns involves the reticular layer of the dermis and is yellowish or white in appearance and blanches on touch and is painful. Heals with scarring. Third degree burns breaches the skin layer and is leathery in appearance without blanching and not painful. Fourth degree burns involves the deeper structures of subcutaneous tissue, muscle, tendons, ligaments and bone and has a charred appearance.

But it is usually noted that the degree of burns varies in the same patient and often is combination of various degrees. Along with degree it is important to estimate the percentage of burns. Though various charts are available, simple and effective way of estimating is by using the area of patient's own closed palm which represents 1% of total body surface area. So an area covering 10 times the palm surface area is equivalent to 10% of TBSA.

Dear Narayan, I agree with the answer same is available in most of the books of different authors but there is no precision in this answer which may give a clear cut line of demarcation.

Thanks

We don't use the degree terminology anymore (though the lay population still does).  We say superficial (aka first degree), superficial partial thickness, deep partial thickness (both second degree), and full thickness (third degree).  Here is a one resource to help distinguish, though they still use degrees. They do a nice job describing the tissue appearance and which structures are affect at each depth of burn. http://hospitals.unm.edu/burn/classification.shtml

Making it more complicated is that there is an area of the burn which may recover or deteriorate over the next few days. That's the Zone of Stasis.  Therefore, the percentages covered by partial thickness or full thickness tissue injury may change over the days following the burn.

For surface area involved, the palmar method is not very accurate, though it's a quick, down-and-dirty way to do it.  The Rule-of-9's is also commonly used, but not precise. The Lund-Browder method is far more accurate, and is what burn centers use. The proportions are different based on age of the person. 

('m a certified wound specialist)

THANKS RENEE CORDREY

@ Renee Cordrey Though u said the degree of burns is for 'the lay population' the link you have cited still classifies burn wound as degrees. And as J R Gaur cites the reason as to Medicolegal cases it's apt to communicate in terms widely used. Even Plastic Surgery texts cite as degrees. And the palm technique as I said is simple and not accurate and helps as a quick guide for triage at high volume centres. Not everybody can be well versed with Lund and Browser charts. Since J R Gaur sir has asked the ques it can be assumed that he isn't working at a burns centre and is merely asking to identify the types for medicolegal, triage and to initiate primary treatment only.

Naveen-- For quick assessment, the Rule of Nines is more accurate, and frankly, easier,  than palms, especially for large areas.  (How many palms is the thigh, for example, or the back?) JR didn't state his setting, or what type of medico-legal reports he writes. Triage is one thing, but a post-mortem, crime scene report, accident investigation, and the like require more detail and accuracy.  But you bring up the good point that the use of the information does guide which tools to use.  I did caution that the link I shared used degrees, rather than thickness indications, but it had good descriptions of how each depth demarcation presents, especially for a non-expert.

Thanks a lot dear Naveen and madam Renee for healthy discussions and answers u have given.I may share with you that I have examined about 130 scenes of crime in dowry death cases due to burning in India. Several times there used to be extensive cross examination  of doctors regarding the degree of burns involving the same question as I asked. Your answers i really appreciate which have enlightened me in good measure. THANKS AND BEST WISHES

I agree with Renée re. 'degrees' of burn being outdated terminology.  For around a decade or so, the classification is as follows:

- Erythema [= NOT a burn]; 

- Superficial Partial Thickness [though tricky, may also use 'mid-dermal partial thickness' to indicate deeper extension]; 

- Deep Dermal (Partial Thickness); 

- Full Thickness. 

As has been noted, most burns are of a mixed-depth, and one must note the concepts pertaining to Jackson's model of burn injury. 

Importantly, with the degree of resuscitation and temporal progression, the 'demarcation' that the author of this question is seeking, may change.

As with most medical concepts, interpretation varies by clinician, and thus the 'precision' is a 'variable' concept (if that makes sense!).

We published a paper in 2013 where we reviewed and discussed what we call a burn injury and in what context we use the terms to include those definitions. I've included the abstract and a link to the entire paper.

In terms of "degrees of injury" we found 1st, 2nd, 3rd, 4th, 5th, and 6th relying on a "Google Search". However, in the scientific literature, we found 1-4 with 5th and 6th only appeared on websites tied to the legal community who were generally classified as "personal injury" attorneys. That said, what we found that we did not anticipate, the use of actual "degrees of injury" was generally two to three times less likely to be used than one of four terms (superficial, partial thickness, deep partial thickness and full thickness). Furthermore, we found that deep partial thickness was only used in the hospital setting.

Anyway, here's the abstract and I've attached a link to the paper.

Through the years, the burn injury has been described using a variety of labels. These labels have ranged from one word terms to phrases including degrees of injury or more descriptive terms. A search was conducted relying on a common general internet search engine. After multiple searches varying the keywords, the top 100 searches identified the most prevalent terms or phrases, ranging from the common to the more obscure. The search was repeated using the most prevalent terms or phrases identified in the common internet search engine, focusing on either the title or abstract for all papers indexed in PubMed. This process narrowed the attention to the most common terms or phrases used by the academics in their published work. This work therefore focused on measuring the specific terms being used today and their frequency of use in the peer reviewed papers indexed in the PubMed system. It is difficult to focus on the unique aspects of any given profession when there is confusion surrounding a common vocabulary. By identifying and noting in the academic literature the most commonly used labels, a point of reference can be created for future work. Furthermore, having a common and accurate set of labels that are uniformly applied across the profession is critical for academia to include in training and education programs for physicians, nurses, and paramedical staff.

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3917143/

First degree burn= superficial burn (burn injury is confined only to the epidermis).

Clinically

First degree bun- Red, blanches on application of pressure, Epidermal involvement only

Second degree burn- Blister burn, Epidermal + dermal involvement

Third degree burn: dry, depressed, charred or white, Epidermis + Dermis + Sub cutaneous tissue involved (clinically even deeper than subcutaneous burn is included in third degree burn

Interesting question, and of course there is no line of demarcation between the  different degrees of burns, it is a continuum. It is us humans who like to put things neatly into boxes and label them. Visual inspection is notoriously difficult even for an experienced burns surgeon. In the living laser Doppler imaging is useful in the first five days to give a fairly accurate depth of burn. Unfortunately these devices are expensive and few burn centres use them routeenly 

In the deceased, histology will give an accurate depth. As has been already said, many burns have a variety of depths, especially scald injuries. I prefer Superficial, SPT, DDPT and FT over degree of burn, but the former is not a perfect classification system either.

But, Roy!

Man or Machine?

Absolutely Man!

Laser Doppler Blood Flow Assessment only helps you to assess the depth od the burn wound. 

So, the experience of the burn surgeon is very very important.

Still most important point is surgeon's experience

2nd degree burn is most large part of  burn injuries.

So,  I would like to recommend more precisely divide on 2nd degree burn superficial, mid, and deep 2nd degree burn

It mean we have to change dressing method differently on each depth of 2nd degree burn  

Actually, in my experience,  the dressing method is similar from 2nd to 3rd degrees burns. The main diference between them is the need for surgical intervention. 

Yes, I agree with you, Vasco, about the key difference being whether to operate or not (with respect to patient comorbidities) for full-thickness (3rd deg) burns. 

However, there are, as Young said, some differences in dressing superficial partial thickness vs. full thickness burns.