The invention concerns a manual resuscitation bag (1) comprising a deformable bag (2) comprising a gas inlet (21) and a gas outlet (22), a first conduit element (3) fluidly connected to the gas inlet (21) of the deformable bag (2), and a first PEP exhaust valve (4) arranged in the first conduit element (3) and fluidly communicating with the ambient atmosphere for venting gas to the atmosphere when the gas pressure, into the first conduit element (3), exceeds a given pressure threshold, said first PEP exhaust valve (4) comprising a valve body (5) and means (6, 12； 7-10) for setting a desired pressure threshold. The means (6,12； 7-10) for setting the pressure threshold comprise a rotatable member (6), actuatable by a user, arranged on the valve body (5) and cooperating with pressure adjusting means (7-10) arranged into the valve body (5), and a support member (12) comprising several markings (11) corresponding to several settable pressure values, arranged between the rotatable member (6) and the valve body (5). The rotatable member (6) further comprises a reading window (60) that can be positioned so as to face one of the markings (11), when the user actuates the rotatable member (6), thereby selecting a pressure threshold corresponding to one of the pressure values indicated by the markings (11) that is readable through said reading window (60).
