**5. Conclusions**

Our results revealed that a higher PEEP, maximum 5 mbar in our investigation, yielded more ventilator-associated advantages than disadvantages with the S-LMA. Results on this were usually significant, especially for a PEEP of 5 mbar, with a larger inspiration volume, greater Cdyn and a lower etCO2 concentration.

Our investigation also demonstrates that significant quantities of air are insu fflate into the stomach under PCV with the S-LMA and a PEEP of up to 5 mbar.

However, it must be noted, that air was collected mainly after induction of anesthesia and ventilation with the S-LMA after insertion of this device. The question therefore arises, as to whether routine aspiration of air from the stomach significantly reduces the incidence of aspiration when the S-LMA, and possibly also other supraglottic airway devices, are used. This could constitute a hypothesis for future studies with a larger sample size.

Overall, the conclusion can at least be drawn that a positive PEEP value is more suitable than no PEEP during ventilation with S-LMA in children.

**Author Contributions:** Conceptualization, M.O.F., T.V., M.C. and C.G.; methodology, T.V., M.C., C.G.; software, C.W.; validation, C.W., E.S. and M.O.F.; formal analysis, C.W.; investigation, E.S.; resources, T.V.; data curation, C.W., A.K.; writing—original draft preparation, M.O.F.; writing—review and editing, M.O.F., E.S., C.W., T.W., T.V., A.K.; visualization, E.S., C.W.; supervision, A.K.; project administration, T.V.; funding acquisition, T.V. All authors have read and agreed to the published version of the manuscript.

**Funding:** The study was financed by the University Medical Centre Mannheim.

**Acknowledgments:** We would like to acknowledge our colleagues from the department of anesthesiology of the University Medical Centre of Mannheim for their collaboration. We want to thank the parents of our research for their support and for all of the opportunities we were given to further our research.

**Conflicts of Interest:** The authors report no conflict of interest.

**Ethical Approval:** The study protocol has been approved by the Medical Ethics Committee II of the Mannheim Medical Faculty of the University of Heidelberg (2010-264N-MA; 22 June 2010) and registered at the German Clinical Trails Register (DRKS00013254).
