Classification of burns by depth
The depth of the lesion determines the main prognostic criterion — the skin's ability to regenerate independently (epithelization).
Superficial burns (heal independently due to preserved germinative zones):
- Grade I: Only the epidermis is damaged.
- Grade II: Damage reaches the germinative layer of the epithelium.
- Grade IIIa: Necrosis of the epithelium and part of the germinative zone, while hair follicles, sweat glands, and sebaceous glands are preserved.
Deep burns (independent epithelization is impossible, surgical grafting is required):
- Grade IIIb (deep): Complete necrosis of the dermis, germinative zone, and partially the subcutaneous tissue.
- Grade IV: Destruction of the entire thickness of the skin and underlying tissues (up to muscles and bones).
Pathogenesis and early diagnostics
Tissue overheating is always the basis of the injury. Its severity depends on the temperature of the agent and the exposure time. Prolonged contact with an object at 42 °C (e.g., a heating pad on an unconscious patient for 6 hours) causes the same skin necrosis as a brief flash of flame. Temperatures below 58 °C lead to moist necrosis, while temperatures above 65 °C lead to coagulative (dry) necrosis.
In the first two days, it is difficult to accurately determine the depth of the injury. Pain sensitivity serves as the main marker. If the patient feels pain when pricked with a needle, treated with alcohol, or when a hair is pulled, the burn is superficial. If sensitivity is absent, it is deep. Additionally, in deep burns of the limbs, edema of the underlying healthy tissues forms, and infrared thermography shows a "cold" zone (decreased heat emission).
Burn disease
This is the body's complex response to thermal trauma. It develops if superficial burns cover more than 15% of the body surface, or deep burns cover more than 10%. It proceeds in four stages:
- Burn shock (from 2 to 72 hours). The leading factor is massive plasma loss (up to 6–8 L/day) and hemoconcentration. A pronounced erectile phase and the development of oliguria are characteristic. Important: a drop in blood pressure occurs only in severe shock.
- Acute burn toxemia (7–8 days). Fluid begins to return from the tissues into the vascular bed, carrying toxins with it. It is accompanied by fever, tachycardia, anemia, and liver and kidney dysfunction.
- Septicotoxemia (from day 10). Associated with the development of infection (Pseudomonas aeruginosa, Staphylococcus). It coincides with the rejection of the eschar. In extensive lesions, burn cachexia develops with marked muscle atrophy and weight loss.
- Convalescence. Gradual recovery, although cardiac and renal dysfunctions may persist for up to 2–4 years.
Principles of treatment and infusion therapy
Any manipulations (including initial wound toilet) begin strictly after pain relief (administration of trimeperidine or morphine). During wound cleaning, large blisters are incised for fluid drainage, while small ones are left untouched. Fibrin deposits must not be removed, as healing occurs beneath them.
Even if there are no clinical signs of shock yet, infusion and antibacterial therapy, as well as tetanus prophylaxis, must be initiated for deep burns covering more than 10% of the area.
Fluid replacement rules:
- The total daily volume of transfusions should not exceed 10% of body weight.
- In the first 8 hours, 1/2 to 2/3 of the daily volume is transfused (since maximum plasma losses occur precisely during this period).
- The Brooke formula is often used for calculation: `(1 ml × Body weight (kg) × Burn area in %) + 2000 ml of 5% dextrose solution`. Grade I burns are not factored into this.
For the Frank index prognosis, remember: "one to three." Superficial wounds yield 1 unit for each percentage of area, while deep wounds yield 3 units at once. If the sum is greater than 90, the prognosis is unfavorable.
Class and exam questions
Why is normal blood pressure not a good sign in burn shock?
In the pathogenesis of burn shock, hemoconcentration and plasma loss come to the forefront, rather than a drop in vascular tone. A decrease in blood pressure is recorded only against the background of extremely severe hypovolemia, when compensatory mechanisms are already exhausted.
What is the main difference between a superficial burn and a deep burn?
In superficial burns (grades I, II, IIIa), elements of the skin's germinative zone are preserved, so the wound can epithelize independently. In deep burns, independent recovery is impossible, and skin autoplasty will be required.
What to do with blisters during the initial toilet of a burn wound?
Large tense blisters must be incised to release the accumulated fluid. It is not recommended to puncture small blisters.
What else to study on this topic
- Methods for calculating burn surface area
- Inhalation injury: clinical presentation and emergency care
- Drugs for local drug therapy (mafenide, silver sulfadiazine)
- Types of necrectomy: chemical and surgical
- Surgical treatment: types of skin grafting in deep burns
Master the entire topic in the "General Surgery" course
This is a summary. The course covers everything tested in classes and exams.
- Complete study guide on "Thermal burns" and 3,335 more pages of the subject
- Assignments and quizzes after every topic — just like in a colloquium
- AI tutor answers questions on the topic anytime
- 70 video lessons on the subject
Other topics in "CHAPTER 10. GENERAL ISSUES IN TRAUMATOLOGY"
Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.