In the early stage of major burns, is there a correlation between survival, interleukin-6 levels and oxygen delivery and consumption?

Abstract

The correlation between haemodynamic and oxymetric parameters, and circulating cytokines has been little studied for the early phase of extensive burns. The aim of this prospective study was to evaluate survival, looking at variations in cardiac index (CI), oxygen delivery (DO 2I) and consumption (VO 2I) indexed to the body surface area (BSA), and circulating interleukin-6 (IL6) levels in the acute stage of major burns. Over a 12-month period, all patients admitted within 6 h of extensive thermal injury with total burn surface area (TBSA) of over 60 per cent, necessitating standardized resuscitation and mechanical ventilation, were included. Routine intensive care monitoring, including pulmonary and femoral artery catheters, was set up. During the first 3 days post-injury haemodynamic and oxymetric profiles were recorded every 6 h. Circulating IL6 samples were taken within 6 h of admission, then daily (at 24, 48 and 72 h). A comparison of the results in survivors (S) and non-survivors (NS) at those previously determined times was made. Ten consecutive patients were studied. Six patients survived (Age = 33 + 10 years; TBSA = 76 ± 11 per cent) and four died (Age = 40 ± 14 years; TBSA = 77 ± 13 per cent). Similar initial hypovolemic profiles were found in both groups. From 24 h, a hyperdynamic status was observed which increased until 72 h. This hyperkinetic evolution was more marked in the survivors (CI: 4.6 ± 2.0 for NS and 6.9 ± 1.5 l min −1 m −2 for S; SVRI: 2125 ± 1288 for NS and 918 ± 232 dynes cm −5 m 2 for S at 72 h). DO 2I and VO 2I were always higher in the survivors. DO 2I and VO 2I and VO 2I increased from admission to 72 h in the survivors whereas a significant drop in DO 2I and VO 2I occured in the non-survivors at 48 h (DO 2I: 536 ± 222 for NS and 1228 ± 268 ml min −1 m −2 for S; VO 2I: 120 ± 50 for NS and 251 ± 56 ml min −1 m −2 for S ( P < 0.01)). Plasma IL6 revealed abnormal values with consistent peaks at 24–48 h in the survivors (respectively 17411 ± 24542 and 10746 ± 11802 pg ml −1) and only moderate peaks in the non-survivors (865 ± 652 and 912 ± 485 pg ml −1). Finally, CI, DO 2I, VO 2I, and circulating IL6 were always higher, and SVRI lower, in the survivors than in the non-survivors. The ability to increase DO 2 and to optimize VO 2 during the ‘turning point’ of 48 h seems to improve the prognosis of critically burned patients: the role of IL6 in this systemic inflammatory response is discussed.