[The monitoring and its clinical significance of the hydrogen peroxide and interleukin-6 levels in exhaled breath condensate of chronic obstructive pulmonary diseases patients undergoing mechanical ventilation].

Objective: To explore the relationship of inflammatory response of the respiratory tract and prognosis of chronic obstructive pulmonary diseases (COPD) patients undergoing mechanical ventilation (MV) in respiratory intensive care unit (RICU).

Methods: Thirty patients with COPD undergoing MV were involved in the study, and divided into survival group (n=16) and non-survival group (n=14). Exhaled breath condensate (EBC) was collected on day 1, 3, 5, 7 after MV. The concentration of hydrogen peroxide (H2O2) in EBC was measured fluorimetrically. The content of interleukin-6 (IL-6) in EBC was measured by enzyme-linked immunosorbent assay (ELISA).

Results: (1) The significantly lower H2O2 and IL-6 levels in the survival group were observed on days 3, 5 and 7 compared with those of day 1 after MV [H2O2 (micromol/L): 0.10+/-0.03 , 0.06+/-0.03, 0.04+/-0.03 vs. 0.19+/-0.14, IL-6 (ng/L): 11.11+/-2.39, 10.35+/-2.09, 8.89+/-2.63 vs. 14.45+/-6.03, all P<0.05]. A significantly lower H2O2 level was observed on day 7 compared with that of day 3 (P<0.05). (2) A significantly higher H2O2 level in the non-survival group was observed on days 5 and 7 compared with that of day 1 (0.16+/-0.15, 0.25+/-0.16 vs. 0.05+/-0.03, both P<0.05). A significantly higher IL-6 level was observed on days 3, 5 and 7 compared with that of day 1 (9.36+/-2.38, 10.55+/-2.33, 14.05+/-4.23 vs. 6.87+/-3.47, all P<0.05). The significantly higher H2O2 and IL-6 levels in non-survival group were observed on day 7 compared with those of days 3 and 5 (all P<0.05). (3) The significantly lower H2O2 and IL-6 levels in non-survivors were observed on day 1 after MV compared with survivors (both P<0.05). There were no marked differences in levels of H2O2 and IL-6 between non-survivors and survivors on day 3 (both P>0.05). A significantly higher H2O2 level in non-survivors was observed compared with survivors on day 5 (P<0.05). In addition, the significantly higher H2O2 and IL-6 levels in non-survivors were observed on day 7 compared with survivors (both P<0.05). (4) The levels of H2O2 and IL-6 in EBC in survivors and non-survivors undergoing MV showed no correlation with acute physiology and chronic health evaluation II (APACHEII) and APACHEIII scores (both P>0.05).

Conclusion: The findings suggest that the levels of H2O2 and IL-6 in EBC are correlated with prognosis of patients undergoing MV, and it may prove to be useful in monitoring inflammatory response in the airway after MV as a guidance of therapy and prognosis in COPD patients undergoing MV.