18.1. Thermal burns
18.1.1. Local changes
Local changes are characterized by the depth and area of the lesion.
For evaluation the depth of burns, in Russia, a classification is usually used, which provides for four degrees of damage. According to the ability of independent full-fledged healing (without scar formation), all burns are divided in two groups: superficial (grade I-IIIA) and deep (grade IIIB-IV) (Table 18.1).
Table 18.1 Characteristics of burn lesions
| Burn | Grade of damage | Depth of damage | Characteristic of damages |
| Superficial | I | Erythema - a lesion within the epidermis | There is no tissue necrosis. Morphological changes - a typical picture of aseptic inflammation with capillary paresis, increased permeability of their walls, edema of the affected area |
| II | Epidermis detachment |
| IIIA | Lesion of the dermis with partial preservation of epithelial elements | The germ layer of the skin and its epithelial appendages are partially preserved: the ducts of the sweat, sebaceous glands, hair follicles, which can also serve as a source of islet epithelialization. Such burns are epithelialized from the bottom of the wound and can heal on their own without scar formation |
| Deep | IIIB | The lesion of the dermis with the complete death of its epithelial elements | All epithelial elements of the skin die; in these cases, epithelialization from the bottom of the wound is impossible. Such lesion never heals on its own without scar formation and requires skin plasty |
| IV | Lesion of the skin with underlying tissues (fiber, fascia, etc.) up to total charring |
| Superficial burns can heal on their own without scar formation. Deep burns without skin plastics can't heal completely. |
Clinical determination of the depth of lesion
Hyperemia and infiltration of the skin with preserved sensitivity is specific for the grade I of damage.
Blisters that are forming immediately or a little later after the injury are characteristic for a grade II and III burn.
With grade II burn, blister is rather small and without tension. Its content is liquid, slightly opalescent or light-yellow. After blister's removing, a Malpighian layer of the epidermis of pink color is exposed. Touching it with a gauze sponge of alcohol is sharply painful. In this case, a positive alcohol test is mentioned.
A grade III burn is characterized by large tense blisters. The blisters are often destroyed. For grade IIIA burns, the content of the blisters is jelly-like, rich yellow in color, slightly stained with blood. The base of the blister is wet, of rose color. The sensitivity of the bottom of the burn wound is often reduced. Alcohol test no longer causes sharp pain (dubious alcohol test).
For grade IIIB burn, the hemorrhagic content of the blister is characteristic. After removing such a blister, the bottom of the burn wound is dry, dim, whitish or marbled. The sensitivity of the wound's bottom is sharply reduced or completely absent (negative alcohol test).
| With grade II burn, the alcohol test is sharply positive, with grade IIIA burn - doubtful, with grade IIIB - negative. |
Tissue necrosis is characteristic for grade III and IV damage. Wet or dry necrosis may be formed.
Wet necrosis appears under the influence of a relatively low temperature, so it is not characteristic of deep burns. Wet necrosis is characterized by marbling or yellowing of the skin, its swelling, welts.
Dry necrosis occurs under the influence of high temperature. It is typical for deeper lesions and manifests itself in the form of a dense scab of brown or black color, which acquires distinct boundaries a few days after the injury. Scab is revealed by changes in skin color, tissue rigidity and lack of sensitivity.
With grade IIIA burn, the scab more often has light yellow, gray, or brown shades, with grade IIIB burn - it is more rigid and dark, and has yellow, gray, or all shades of brown, with grade IV burn, the scab is brown or black, rigid. Differential diagnosis of the depth of lesions with a scab in the first days after the injury is difficult and most often has a presumptive character. It is especially difficult to distinguish the burn cases of grades IIIA and IIIB. The final diagnosis can sometimes be made only after rejection of the scab with the appearance of insular epithelialization of the wound bed (grade IIIA) or its absence (grades IIIB-IV).
Clarification of the diagnosis in the early stages can help the correct assessment of the affected temperature and the duration of the effect of the traumatic agent.
| With significant exposure, a less hot traumatic agent can lead to a deeper lesion. |
Prolonged contact with hot water vapor usually results in deeper burns than instant exposure to temperatures of hundreds of degrees Celsius. The most severe burns occur with a combination of prolonged exposure and high temperature. A vivid confirmation of this are napalm lesions, which in more than 80% of cases lead to deep burns.
Determination of lesion severity
In addition to depth, the severity of the lesion is affected by the relative area (as a percentage of the entire surface of the body) and the localization of the burn.