Physiological response to plasma exchange in patients in burn shock

The physiological consequences of major thermal injury center around profound, life-threatening shock occurring in conjunction with the burn and consisting of two pathological syndromes: hypovolemic and cellular shock. Intravascular hypovolemia following major thermal injury results from increased capillary permeability with subsequent loss of intravascular fluid into the interstitium. The purpose of this study was to evaluate the effect of a therapeutic regime involving the removal of the circulating factors by performing plasma exchange. Fourteen adult patients with burns of 40% total body surface area (TBSA) served as subjects. Seven were randomly assigned to the control group which received standard burn shock resuscitation. Seven were randomly assigned to the treatment group which received the same resuscitation in combination with plasma exchange. The study period was the first 48 hours postburn with the plasma exchange procedures performed as soon as was clinically feasible. A total of 937 measurements of physiological variables were made on each patient. These included vital signs, cardiopulmonary parameters, respiratory status, and serum content analysis measured upon admission and every 4 hours thereafter during the study period. Hourly fluid intake and output records were compiled. Data were analyzed for statistical significance. The findings were as follows: the sample was unevenly distributed, with the treatment group more critically ill than the control on the basis of the variable or percent TBSA full-thickness injury (p < .01) and the incidence of documented inhalation injury. No significant difference was found between the groups on the variable of fluid requirement, either in subjects with or without associated inhalation injury. Plasma exchange significantly decreased platelet count (p < .05) in the treatment group when compared with the control but did not alter other serum chemistry values. The coagulopathy reported to occur in burn patients was not observed in this group of 14 subjects. The plasma exchange group was in significantly (p < .05) more normal base excess balance at both postburn hour 16 and 24 than the control. There was no evidence that plasma exchange performed during burn shock for the purpose of removing circulating factors was harmful in any way to the treatment subjects.