Materials and methods

Introduction

• hyperpyrexia - tachycardia - hypotension - hyperventilation - oliguresis - confusion and psychic disorientation - aggravation of tegumentary lesions.
• From the microbiological point of view, we observed ~ in the event of sepsis - positivation of the haemocoltures.
• With regard to surgical procedures we performed 42 escharectomies, divided into two subgroups: 27 early operations (by day 7 post-burn) and 15 late operations.

Three septic episodes occurred in seven of the patients between day 10 and day 35 post-burn (average time 19.3 days). The patients MOSt subject to sepsis were the younger ones, with more extensive and deeper burns, especially when the areas remained critical for longer periods. The septic episodes also tended to occur in patients presenting previous systemic pathologies (e.g. hypertension and asthmatic bronchitis) and who were hospitalized longer. From the aetiological point of view (as shown by haernocultures), Staphylococcus aureus was involved in six cases and Enterococcus and Candida in one case each.
The organisms isolated in skin samples were as follows:

• Staphylococcus aureus: 95%
• Pseudomonas auriginosa: 48%
• Enterococcus: 33.3%
• Candida albicans: 14.3%
• Enterobacter cloacae: 14.3%
• Candida parapsilosis: 4.8 %

The eight septic episodes occurred in those patients who received time-deferred surgical therapy.

We considered the results in relation to the following

1. Effect of sepsis on the immune response

Comparing the average values of the two groups of patients (septic and non-septic) at the same postburn moment, it emerged that in the group with sepsis there was:

• an increase in leucocytes, factor I and C-reactive protein
• a decrease in albumin, fibronectin, alpha 2 macroglobulin and T4 lymphocytes
• normal values of blood platelets, C3, C4, IgG, IgA, IgM, total proteins, cortisol, T8 lymphocytes and T4/T8 ratio.

Analysing the non-septic group, we found:

• an increase in leucocytes, blood platelets, factor I and C-reactive protein
• a decrease in albumin
• normal values of C3, C4, IgG, IgA, IgM, total proteins, fibronectin, alpha 2 macroglobulin, cortisol, T4 and T8 lymphocytes and T4/78 ratio.

2. Effect of early and late surgical treatment on the immune response

Patients subjected to early escharectomy showed:

• a significant increase in blood platelets and C4
• a decrease in fibronectin and IgM, factor I and white blood cells, albumin, total proteins and alpha 2 macroglobulin
• no significant variations in C3, IgG, IgA, C-reactive protein, cortisol, T4 and T8 lymphocytes and T4/T8 ratio.

Patients subjected to late escharectomy showed:

• a significant increase in C3, C4, IgG, IgA, fibronectin and total proteins, albumin, alpha 2 macroglobulin and T8 lymphocytes
• a decrease in IgM, C-reactive protein, white blood cells and T4/T8 ratio
• no variations in blood platelets, factor 1, cortisol and T4 lymphocytes.

Our data indicate some conclusions that are in contrast with data in the literature. The monitoring of the immunological profiles of burned patients is a very difficult task, also in view of the many possible variables, such as:

• age (a favourable factor in children under the age of two years and in elderly patients, respectively because of immaturity and deficiency of immune reactions)

• previous diseases (diabetes, malnutrition, cardiopathologies, immune deficiencies, cortisone therapy) burn depth and percentage type of accident (involving also respiratory system injuries due to toxic gas inhalation)

• possible concomitant injuries.

Discussion

In agreement with data in the literature (1, 2, 3, 4, 5, 6, 7), our research shows that burned patients present a high susceptibility to infective risks.
It is not possible to define exactly which area of immunocompetence is most involved. Many authors (1, 8, 9, 10, 11) refer to T-lymphocytes, in consideration of the fact that their function often changes in burns.
These observations were not however confirmed by our data, as the immunological parameters monitored in our research gave rise to contrasting results.In accordance with the literature, it emerged that in burned patients (septic and non-septic):

• Leucocytes showed rapid increases (to as much as twice the normal values). Early post-burn leucocytosis generally implied high levels of B cells, monocytes, neutrophil granulocytes and progenitor cells in immature forms. In the late phase the main presence concerned T cells. It is also important to remember that topical use of silver sulphadiazine and povidone iodine may contribute to change the values. These substances cause leucocytopenia that disappears within one or two days after suspension of topical treatment (2, 9, 11, 12, 13, 14, 15).
• Factor I initially decreased because of its conversion into fibrin in areas where microthrombosis phenomena occurred after day 2 post-burn. It then increased to twice the normal value and stayed at that level for many weeks
• C-reactive protein increased progressively, reaching a plateau where it remained for many weeks. Normalization usually occurred after several months
• Total proteins diminished after the burn trauma, and in particular albumin decreased steadily (16, 17).
• T4 helper lymphocytes diminished (8, 14, 18).

In contrast with the results in literature, we did not find any significant correlations with parameters that are considered critical in the immunological balance, such as: T4/T8 ratio, fibronectin and complement factors (with regard to this last parameter the values in our study remained normal, without any increase).
Alpha 2 macroglobulin, a high molecular-weight protein (850 000 D) that generally increases during the first days and then rapidly stabilizes, behaved almost normally, remaining within the minimum values of normality.
Cortisol, which usually increases two to four times and is directly proportional to the gravity of the patient's burns, remained within the maximum values of normality (19).
The above data make it difficult to form any systematic conclusions. The standard behaviour of many parameters shows that the physiopathology of the burn is steady and involves stable immunological functions.
However, our contrasting results show that it is particularly difficult to make an accurate profile of the immunological dysfunctions of burned patients.
We also believe that immunocompetence tests cannot be globally and universally determined. It is clear that there is no exact laboratory standardization of research methods. In the light of our data, we are in agreement with those who believe there is a prevalent compromission of cell immunity at the expense of uninuelear cells that could act suppressively after burns.
On the basis of our data, we think it possible to extrapolate some predictive signs of sepsis, as we observed that certain very clear immunological dysfunctions appear during the aseptic phase and not before. This is a consequence of sepsis, not a cause.
To conclude, since the eight cases of sepsis occurred only in the group of patients subjected to late surgical treatment, we have further confirmation that early escharectomy is a fundamental therapeutic defence against the appearance of sepsis in burned patients.

RESUME. Les complications infectieuses sont les plus redoutées dans le pronostic des cas des brûlures sévères, et pour les réduire il faut conduire une thérapie antibiotique et nutritionnelle appropriée. L'escarrectomie précoce ou tardive peut modifier le début de la sepsis. Les auteurs, dans une étude effectuée au Service de Chirurgie Plastique et Centre de Brûlés de l'Hôpital Niguarda, Milan (Italie), ont analysé l'aspect immunologique dans un groupe de patfents brûlés pour faire une comparaison entre leurs données et celles de la littérature. Ils se sont proposés d'établir s'il était possible d'associer les changements de certains paramètres immunologiques avec la manifestation des phénomé, nes septiques.

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