An apparatus for treating a tissue site includes a dressing, an oxygen source, a valve, and a negative-pressure source. The dressing is configured to be sealed around the tissue site. The oxygen source is fluidly coupled to the dressing and configured to provide a low flow of oxygen. A first port of the valve is fluidly coupled to the dressing and the valve moves between a closed position preventing flow through the valve and an open position permitting flow through the valve. The negative-pressure source is fluidly coupled to a second port of the valve and provides negative pressure to the second port of the valve at a non-therapeutic level. The valve separates the negative-pressure source from the dressing and selectively opens when a positive pressure is applied on an upstream side of the valve.