Hyperoxic ventilation improves survival in pigs during endotoxaemia at the critical hemoglobin concentration

Aim of the studyRecently it has been demonstrated that short term hyperoxic ventilation (HV) can improve glucose metabolism, reduce pulmonary and hepatic apoptosis, and improve gastrointestinal perfusion during acute sepsis. However, it is unknown whether additional O2 improves survival. Therefore we investigated the effects of increased plasma O2 on survival during extreme anaemia and concomitant endotoxaemia in order to quantify the efficacy of HV.MethodsEndotoxaemia (Salmonella abortus equi-LPS) was induced in 14 anesthetized pigs ventilated with room air (FiO2 = 0.21). Simultaneously, animals were haemodiluted by exchange of whole blood for 6% hydroxyethyl starch (200,000:0.5) until the individual critical hemoglobin concentration (Hbcrit) was achieved (outermost limit of tissue oxygenation). Subsequently, animals were either ventilated with an FiO2 of 0.21 (NOX, n = 7) or an FiO2 of 1.0 (HOX, n = 7), and observed thereafter for 6 h without further intervention.ResultsHV significantly prolonged survival time at Hbcrit (NOX, 30 [27/35] min; HOX, 172 [111/235] min, p < 0.05). In contrast to the NOX group, HV maintained MAP, and improved DO2 and tissue oxygenation in the HOX group.ConclusionThe improvement of survival, oxygen transport and tissue oxygenation seems to underline the efficacy of HV during endotoxaemia and concomitant acute anaemia. Further studies are needed to transfer these results into daily clinical practice.