RT Journal Article SR Electronic T1 G446(P) Expired hydrogen sulphide: a potential marker of infection? JF Archives of Disease in Childhood JO Arch Dis Child FD BMJ Publishing Group Ltd and Royal College of Paediatrics and Child Health SP A176 OP A176 DO 10.1136/archdischild-2017-313087.439 VO 102 IS Suppl 1 A1 N Bee A1 R White A1 A Petros YR 2017 UL http://adc.bmj.com/content/102/Suppl_1/A176.1.abstract AB Introduction There is increasing interest in using plasma Hydrogen Sulphide (H2S) or it’s metabolites as markers of pathological conditions or as a predictive marker of outcome. We speculate that if H2S increases in the bloodstream it may diffuse into alveolar gas and be detected in expired gas.Aim To determine whether H2S is expired in higher quantities in ventilated children or neonates with sepsis compared with ventilated control subjects.Methods Following ethical approval and parental consent patients were allocated into control or septic groups. Criteria for the sepsis group was suspected infection, two or more SIRS criteria and one organ failure. Thus in keeping with the International Paediatric Sepsis Consensus Conference criteria (Goldstein 2005). A chromatograph was used to measure H2S in parts per billion. A 1–2ml sample of expired gas was taken from the endotracheal tube and analysed. A repeat sample was taken after 30 min and repeated daily up to a maximum of 5 days or until extubation. Clinical data including C Reactive protein (CRP) was collected. Room air was analysed to determine atmospheric H2S.Results Each group contained 20 subjects. Table 1 shows the median age (m), CRP and expired hydrogen sulphide on day 1.View this table:Abstract G446(P) Table 1 Mann Whitney U-test for the expired hydrogen sulphide in the two groups on sample one revealed a p value of 0.0001. Normal atmospheric H2S was measured daily and ranged between 30–36 ppb. Graph 1 shows the trends in H2S and CRP. H2S levels between day 3 and 5 decreased towards control levels and were not significantly different. There was a significant overall difference demonstrated between the two groups using 2-way ANOVA multiple comparisons (p=0.0001).Conclusion H2S can be detected in expired lung gases. Higher quantities are seen in septic patients compared with controls. More detailed information on timing of rise and it’s translation into clinical practice are ongoing.