Abstract: A portable apparatus for ventilation support to persons with respiratory distress is provided with a compressed air pump. The pump may be connected to the mouth or the nose via a tube for generation of pressure pulses with an individually adaptable air volume. The pump comprises a rigid container having two symmetrical halves and with a flexible membrane which is located as a laterally reciprocating diaphragm between the two container halves. These are provided with check valves permitting ambient air to be fed into the pump and from the pump into the tube while the membrane wall is moved, for generation of a pressure pulse. The pump is provided with a flexible pull device for reciprocating operation of the membrane in the container. The pull device extends via pulley wheels to a driving device located substantially in the same plane as the container and beside it.