A non-lineal mathematical model of capillary dynamic has been constructed to study the reanimation stage and the effect that different treatments have on burn patients. This analysis allows a qualitative and quantitative knowledge of the dynamic behaviour of variables very difficult to quantify in daily practice, like plasma volume, net liquid shift in burned and non-burned areas, etc.The value and fidelity of the model was obtained by comparison of the reckoned results with those measured in a serie of patients of the Burn Unit of a General Hospital.