Inhalation injury in severely burned children does not augment the systemic inflammatory response

INTRODUCTION Inhalation injury in combination with a severe thermal injury increases mortality. Alterations in inflammatory mediators, such as cytokines, contribute to the incidence of multi-organ failure and mortality. The aim of the present study was to determine the effect of inhalation injury on cytokine expression in severely burned children. METHODS Thirty severely burned pediatric patients with inhalation injury and 42 severely burned children without inhalation injury were enrolled in the study. Inhalation injury was diagnosed by bronchoscopy during the first operation. Blood was collected within 24 hours of admission and again at five to seven days following admission. Cytokine expression was profiled using multi-plex antibody-coated beads. Significance was accepted at a p value of less than 0.05. RESULTS The mean percentages of total body surface area burned were 67% +/- 4% (56% +/- 6%, third-degree burns) in the inhalation injury group and 60% +/- 3% (45% +/- 3%, third-degree burns) in the non-inhalation injury group (p value not significant [NS]). Mean age was 9 +/- 1 years in the inhalation injury group and 8 +/- 1 years in the non-inhalation injury group (p value NS). Time from burn to admission in the inhalation injury group was 2 +/- 1 days compared to 3 +/- 1 days in the non-inhalation injury group (p value NS). Mortalities were 40% in the inhalation injury group and 12% in the non-inhalation injury group (p < 0.05). At the time of admission, serum interleukin (IL)-7 was significantly increased in the non-inhalation injury group, whereas IL-12p70 was significantly increased in the inhalation injury group compared to the non-inhalation injury group (p < 0.05). There were no other significant differences between groups. Five to seven days following admission, all cytokines decreased with no differences between the inhalation injury and non-inhalation injury cohorts. CONCLUSION In the present study, we show that an inhalation injury causes alterations in IL-7 and IL-12p70. There were no increased levels of pro-inflammatory cytokines, indicating that an inhalation injury in addition to a burn injury does not augment the systemic inflammatory response early after burn.