Annals ofBurns and Fire Disasters - vol. IX - n. 4 - December 1996

HAEMATOLOGICAL CHANG IN SEVERELY BURNED PATIENTS

EI-Sonbaty M.A., EI-0tiefy M.A.

Burn Unit, Assiut University Hospital, Assiut, Egypt

SUMMARY. A prospective study was undertaken to determine the haematological changes occurring in severely burned patients. The study included 30 patients (18 females and 12 males), all with flame burns (range, 30/65% TBSA). Daily estimation of routine haematological laboratory values was carried out. The individual mean of each of these values in patients who survived (21 patients) was statistically compared with that of patients who died (9 patients). It was found that laboratory manifestations of anaemia were evidenced six days postburn and two days earlier in the non-survivors. Leucocytosis was manifested soon after the bum and was steady in the survivors. The platelet count showed decreased levels in both groups, with significantly increased levels in the survivors by the end of the first week.

The patient with a major bum has suffered one of the most severe forms of trauma. The pathological changes produced in the circulatory and respiratory systems are complex, and failure to understand their progress and therapeutic management can cause the patient further problems. It is well known that a severely bumed patient presents the greatest dysregulation of homeostasis of any injury.' Muir has shown that a general relationship exists between the extent of deep bum and the amount of red cell destruction.' Baxter observed a shorter life span of red blood cells.' Enremus reported that 10% of the total red cell mass is injured during the bum process.' All these changes have been attributed to the presence of some type of detrimental plasma factor, because when the red cells are injected into a normal person they survive a normal length of time.'Also, the serum of bum patients contains a substance that inhibits erythropoiesis.
Peripheral blood phagocytic cells (granulocytes and monocytes) may also be influenced, with serious consequences for infection resistance, which is known to detenorate in bum injury.
Thrombocytopenia is almost universal in bacterial infections associated with bacteraernia and is usually the result of increased platelet consumption. The reduced platelet count may be an isolated finding or it may be associated with disseminated intravascular coagulopathy. Thromboeytopenia usually occurs early and can be an early indication of bacteraernia in bum patients!

The study included 30 patients (18 females and 12 males), all with flame burns ranging from 30 to 65% TBSA. Their ages varied between 17 and 47 years (mean, 25 years). In addition to the study groups there was a control group consisting of ten healthy volunteers of the same age and sex range.
The study group was admitted to the Burn Unit of Assiut University Hospital in the period January 1992/January 1993. All the patients received intensive care and resuscitation immediately after admission. Daily determination of blood urea, scrum creatinine, serum sodium, serum potassium and blood gases was performed during the first week and thereafter as needed. Daily estimation of erythrocyte count, haemoglobin percentage, haematocrit value, leucocyte count and platelet count was carried out for the first eight days in both groups and in the patients who survived until the end of the second week. Other routine monitoring data were recorded during the period of study. In a trial to identify ominous parameters during resuscitation of severely burned patients, we made a statistical comparison between the individual data of the haematological changes in the 21 patients who survived ("survivors") and those of the nine patients who died ("non-survivors").

Haemoglobin concentrations showed significantly high levels immediately after the burn, especially in the non-survivors. This high level decreased gradually to below control level by day 4 post-burn in the non-survivors and by day 6 post-bum day in the survivors. The same pattern of changes was noticed regarding haematocrit levels and red blood cell count (Fig. 1).
There was a highly significant leukoeytosis in both groups compared with control. Leukocytosis in the survivors remained constantly at high levels, while in the nonsurvivors it showed oscillating levels until death (Fig. 2).
The platelet count, on the contrary, showed a significant decrease in levels below control, reaching very low levels in the non-survivors, while it increased steadily in the survivors after day 4 post-bum, reaching levels above control by day 7 post-burn and thereafter (Fig. 3).

Discussion

The daily estimation of haemoglobin percentage, haematocrit value and red blood cell count in the severely burned patients in our study showed that there was progressive anaemia after the initial haemoconcentration phase and that there was a correlation between the degree of anaemia and burn severity. These data are consistent with those of Lobel et al.

Fig. 1 - Mean values of red blood cell count in survivors, non-survivors and control groups. Fig. 2 - Mean values of white blood cell count in survivors, non-survivors and control groups. Fig. 3 - Mean values of platelet count in survivors, non-survivors and control groups.

Anaemia in bum patients has been postulated as being due to the accelerated decomposition of erythrocytes, since a massive blood transfusion in such patients cannot counter the defect secondary to the effect of bum-induced factors which cause morphological changes in red blood cells.` The degree of erythrocyte destruction, measured with radio-labelled chromium, has been shown to be related to burn severity. The abnormal red cell morphology resembles echinocytes, a form which is known to result when erythrocyte ATP concentration is depleted," and follow-up research has found that morphological changes in red blood cells are reversible. The severely burned patients became severely anaemic by day 4 post-burn, when blood transfusion had to be initiated in order to replace destroyed red blood cells and to improve tissue xygenation. Significant leukocytosis was noticed in both survivors and non-survivors in this study, with constant high levels in survivors.
These findings are consistent with those of most reports. Gruber and Farese reported peripheral leukocytosis that lasted for 35 days or more in murine granulopoiesis after inducement of a standardized sublethal third-degree burn.` A similar finding was reported by D'Alesandro and Gruber in an experimental study on rats, where after a 30% thermal injury leukocyte quantities were three to five times normal values.` The platelet count was observed to be significantly increased by day 7 post-burn in the survivors. This in crease may be considered a good prognostic parameter during the treatment of severely burned patients. Similar changes in platelet level were reported in D'Alesandro and Gruber's experimental study. On the contrary, there was a significant and progress ive decrease in the platelet count in the non-survivors until death ensued. This thromboeytopenia is usually the result of increased platelet consumption or of decreased produc tion by bone marrow.
Housinger et al. studied the relationship between plate let count, sepsis and survival in paediatric bum patients concluding that a decline in the platelet count preceded other signs of sepsis in all cases and that a platelet count below 0. 1 x 1 O'fl for more than four days was uniformly associated with death.
In the light of these data, it may be concluded that the monitoring of the platelet count is of great importance during the resuscitation and care of severely burned patients. Whenever the platelet count begins to decline, all measures to support the general condition of the burned patient should be initiated, including the administration of intravenous fluids and antibiotics, optimal care of the burn wound, debridement or escharectomy, and blood transfusion.

RESUME. Les Auteurs ont effectué une étude prospective pour déterminer les modifications hématologiques qui se produisent chez les grands brûlés. L'étude comprenait 30 patients, dont 18 femelles et 12 mâles, tous atteints de brûlures par flamme (extension, 30 à 65% de la surface corporelle totale). Les valeurs hématologiques routinières ont été évaluées journellement en laboratoire. La moyenne individuelle de chacune de ces valeurs chez les patients qui ont survécu (21 patients) a été comparée statistiquement avec celle des patients décédés. Les Auteurs ont trouvé que les manifestations en laboratoire de l'anémie se produisaient six jours après la brûlure (deux jours plus precocement chez les patients décédés). La leucocytose se manifestait peu de temps après la brûlure et restait constante chez les patients survécus. Le nombre des plaquettes était réduit chez tous les patients, mais le niveau chez les patients survécus augmentait en manière significative avant la fin de la première semaine.

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