SUMMARY. All fluid resuscitation techniques in use today give satisfactory results for survival, but the experience of the Turin Bums Centre, confirmed by other clinical and experimental research, shows how the various solutions employed in resuscitation treatment in the emergency phase can have different effects. Although the sodium intake in the various methods is more or less constant (0.4-0.6 mEq/kg/burn percentage), it is important to consider the physiopathological significance of the resuscitation achieved by the various techniques in order to make the best use of the particular characteristics of each single technique. There is no justification for the application of a standard formula, even if this is adjusted during therapy. It is preferable to base therapy closely on the individual clinical case and in particular to modify it by varying as necessary the sodium content in the solution rather than the velocity and the quantity of the fixed sodium content infusion. In order to facilitate the choice of the most suitable fluid regimen for each individual patient and to eliminate the limits imposed by the single formula method, a series of pathological conditions are indicated that can best be treated with different approaches, as shown by a comparison of various parameters, e.g. diuresis, oedema, cardiac output, extrarenal water loss and proteinaemia.

Over the years numerous resuscitation formulae have been developed, varying both in the type of solution employed and in the quantity and method of administration (Evans, 1952; Brooke, 1966; Parkland, 1970).
The successes achieved have in some way slowed down the search for new therapeutic solutions in light of the fact that various researchers, using different methods, have reported satisfactory results with statistically comparable survival rates (Hall, 1978; Bowser, 1983).
However, the physiological consequences of the resuscitation vary according to the different types of fluid used, giving rise to a number of clinical conditions, each of which in our opinion needs a different therapeutic approach.
We therefore believe that an inflexible and acritical preference for the single formula to which one is most accustomed represents a limitation compared to a more personalized resuscitation formula, i.e. one that is closer to the real needs of the individual patient, also in view of the fact that no formula, for example, takes into account the depth of the lesions, which considerably affects the gravity of haemodynamic alterations (Magliacani, 1982).
Examination of the various solutions commonly used shows that Ringer's lactate solution (RL) obtains the desired effect using a fluid load that is noticeably higher than that of the hypertonic solutions (HSL), with 4.9 ml/kg/percentage bum in the first 24 h compared to 2.5 ml, while the sodium load is higher in the hypertonic solutions (Tab. 1).
The diuresis obtained with RL is more abundant than diuresis with FISL, but the diuretic index, i.e. the ratio between fluid infused and fluid eliminated, is the same. The hypertonic solution would rather seem to give the kidney better protection from hypoperfusion since, in relation to the fluid administered, diuresis in the first 24 h is higher than in controls receiving RL.
Serum osmolarity is clearly higher in HSL resuscitation (Tab. 2).
Water and sodium loss, by secretion and through the burned areas, and weight gain are greater in the RL groups than in the HSL groups, even when plasma is administered in the 2nd 24 h period (Tab. 3).
Comparison between resuscitation with RL and with low molecular weight Dextran shows in the latter case higher cardiac output, lower haematocrit and a slightly increased central venous pressure (Tab. 4).
In resuscitation therapy with high molecular weight Dextran (Dextran 70) the quantity of fluid used and hourly diuresis are lower than with Ringer (Tab. 5).
The burn shock causes an impairment of the functionality of the cell membranes, especially at the level of skeletal muscle. There is penetration of water and sodium into the cell, accompanied by an escape of potassium and a modification of the membrane's potential which favour intracellular oedema.
Extracellular oedema is another subject of study and it has recently been shown that a decisive factor in its pathogenesis is the hypoproteinaemia caused by the microvascular damage in the capillaries following the lesion, which favours flow from the vessels to the interstitium, even in zones at some distance from the damaged tissues (Demling, 1984). The increase in extravascular fluid is not therefore due only to increased vasal permeability to proteins but rather to the reduction in intravasal oncotic pressure resulting from hypoproteinaemia.
Another cause of the oedema would seem to be a- modification in the interstitial substance, which increases its water need.
Cellular oedema is less marked when HSL are used, as they favour the passage of water in the opposite direction, i.e. from the cell to the extracellular space.
With RL, protemaemia is higher but oncotic pressure is lower, in contrast to the efTect of colloid solutions, which thus limit the formation of extracellular oedema (Tab. 6).
This explains the lower gain in weight, which increases by 10 per cent and more when RL is used.
Most Centres however now use above all saline solutions containing sodium, and Dextran has been more or less abandoned.
Sodium is the main extracellular cation, and fluid therapy with low sodium would appear to modify the homoeostasis of the milieu int~rieur.
The amount of sodium administered in the various formulae is approximately the same. It can be concluded, also taking into account body weight and burn percentage, that 0.4-0.6 mEq/kg/burn percentage of sodium is sufficient (Tab. 7).
It is therefore clear that although the various resuscitation techniques may be equally successful so far as survival is concerned, a number of differences emerge, indicating the possibility of a more individually aimed use (Tab. 8).
In point of fact both the type and the quantity of fluids necessary for correct resuscitation depend on the gravity of the burn, on age, on concomitant and/or previous diseases and on the association with other traumas.
In other words a bum covering over 40 per cent of body area has a different prognosis from a lesser bum.
Burns in children and the elderly must therefore be considered different from burns in the adult, whose cardiovascular system possesses greater reserves and capacity for recovery.
Similar considerations must be made for the cardlopathic or the bronchopneumonopathic subject, whose general conditions are weaker than those of the healthy individual.
For these reasons we believe that routine use of a single rigid formula may achieve good results in the reanimation of some patients but may be unsatisfactory in others.
On the basis of our experience we would propose certain indications which we believe can provide a fluid resuscitation therapy that is more appropriate for the conditions of each single burn patient (Magliacani, 1987).
In bums covering less than 40 per cent (30 per cent in children) in healthy adults good results can be obtained with any type of formula and solution.
In children with over 30 per cent burns, the elderly, the polytraumatized and patients suffering from cardiac or respiratory disease, better reanimation results are obtained with hypertonic solutions, while in cases arriving late for observation it is possible to make use of the capacity of the Dextrans to reduce the haematocrit and to increase oncotic pressure, without excessive administration of fluids.
However the philosophy of reanimation really requires individual solutions for individual problems.
We are therefore in agreement with Monafo (1984), who suggested restoring the water/salt balance by infusing saline solutions of varying sodium content.
The undeniable assumpion is that the biological reaction is an important variable. The haemodynamic changes are different even in apparently similar burns and a personalized therapy is therefore to be preferred to any rigidly predetermined therapy.
We therefore suggest that whenever necessary during treatment the fluid therapy being administered should be adjusted, not merely by modifying the quantity of the substitutive fluid by varying the speed of infusion but more rationally by altering the sodium content of the infusion fluid in accordance with the patient's real needs. At the Turin Centre, Parkland's formula is used to calculate fluid requirements in the first 8 h, corresponding to 50 per cent of requirements in the first 24 h, and Ringer's lactate solution is administered.
The clinical parameters (particulary diuresis) and laboratory tests subsequently indicate the strategy to follow in the choice of the most suitable fluid therapy for the patient's individual needs.
Briefly, in the 16 h post-burn, our protocol for children provides for an hourly diuresis of 1.5-2.2 ml/kg, which can be obtained by administering a) 1 ml/kg/percentage burn as an isotonic electrolyte solution, replaceable by HSL if results are unsatisfactory, in order to avoid possible fluid overload in very young children with low circulating mass, as the extracellular portion of the fluids is less stable due to less active diffusion phenomena, and b) 0.5 ml/kg/pereentage burn of plasma.
Healthy adults continue to receive the Parkland formula (2ml/kg/pereentage burn), while elderly patients are treated with the hypertonic solution at a rate of 1 ml/kg/percentage burn.
Clearly all therapy of this nature must be accurately and continuously monitored as the individual response is extremely variable and unpredictable, so that if necessary the initial decisions will have to be modified.
For example, RL should be used, increasing the originally intended volume, in the event of azotaemia with oliguria and high osmolarity; with oliguria and low osmolarity it is preferable to use HSL with variable sodium content, obtained with the addition of sodium lactate to the Ringer solution (mEq/lltre 150-250 of sodium and 280-380 of osmolarity). Dextran 70 can be used in other cases, when the haematocrit is high and diuresis moderate.
We observed that the fluid load in patients we treated with solutions of 130 mEq/lltre of sodium was about 40 per cent higher than the patients infused with more personalized solutions, who did not present greater sodium requirements and had a slightly enhanced survival rate.
These findings are supported by Monafo's results and they may provide food for thought if the qualitative level of resuscitation today, however satisfactory, is to be improved.

No great, differences currently exist between the ,various schools in the choice of appropriate reanimation therapy and even where they do exist, the results are-generally positive.
However, as we learn more about the physiopathological aspects of the burn disease, especially as regards late manifestations, we should be encouraged to adopt non-traditional therapeutic procedures in order to avoid the complications that may lead to failure in the more advanced phases of the disease.
The validity of the numerous formulae in routine use is increasingly being examined, with the dual purpose of identifying their advantages and disadvantages in relation to the evolution of the burn disease and of integrating them with new discoveries in the field of burns physiopathology.
The large amount of current research will make it possible to assess scientifically the validity of a number of empirically introduced but nevertheless successful methods.
If our purpose is to improve still further the good survival rate that has already been achieved in this type of traumatized patient, we must above all not forget the observation made by Schwartz in 1979 that every formula should be taken as an indicative protocol, an element of reference, a starting-point and a guideline, which may however require correction and modification. Irrational adherence to fixed formulae, at all costs and in all cases, leads to foreseeable and avoidable failures.
To achieve our goal it is essential to unify the various methods. In this way it will be possible to create a common therapeutic protocol permitting an accurate assessment of results so far achieved and constituting a basis for all to accept, so that more sophisticated techniques can be jointly developed.

RÉSUMÉ. Toutes les techniques transfusionnelles dont on se sert aujourd'hui fournissent des résultats satisfaisants quant aux chances de survie du patient, mais l'expérience vécue au centre de Turin, associée à d'autres recherches cliniques et expérimentales, démontre que, au cours du traitement de réanimation pendant la période d'urgence, les différentes solutions adoptées peuvent produire des effets tout différents. Bien que la quantité de sodium administrée de façon différente apparaisse relativement constante (0,4-0,6 niEq/kg/ pourcentage de brûlure), c'est sur la signification physiopathologique des procédés de réanimation mis en oeuvre qu'il faut prêter l'attention pour utiliser au mieux les caractéristiques particulières de chaque technique.
Comme l'on retient qu'il est utile et justifié de dépasser l'application rigide d'une formule standard, même susceptible de changements au cours du traitement, on suggère d'adopter une thérapie différente et appropriée au cas clinique singulier et, en particulier, de corriger la thérapie prévue en variant au fur et à mesure le contenu de sodium de la solution plutôt que de modifier la vitesse et la quantité de transfusion de solutions au contenu de sodium déterminé, Pour adapter la fluidothérapie au cas de chaque patient, en la libérant des limites imposées par la formule unique, on suggère par conséquent une série d'indications liées à des réalités pathologiques qui peuvent être mieux corrigées selon la manière dont on l'approche, comme il en résulte de la confrontation des différents paramètres comme, par exemple, la diurèse, l'oedème, le débit cardiaque, les pertes hydriques extra-rénales, la protéinémie.

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