A breathing apparatus comprising: an exhalation membrane pressurizable from a first pressure to a peak pressure; an exhalation chamber surrounding said exhalation membrane , wherein said exhalation membrane ) expands inside said exhalation chamber as said exhalation membrane is pressurized from said first pressure to said peak pressure; an expiratory flow path communicating with said exhalation membrane ; an inspiratory flow path communicating with said exhalation chamber; and at least one intake portal communicating with said exhalation chamber , characterized by a three way valve comprising a first valve , a second valve , and a third valve which are in communication with a first outlet , a second outlet , and a third outlet , respectively, said first valve connects the patient's expiratory flow to said exhalation membrane , said second valve connects the patient's expiratory flow to atmosphere, said third valve connects said exhalation membrane to atmosphere at a location spaced from said expiratory flow path , wherein said three way valve is configured such that said first valve is in an open position while said second valve and said third valve are in a closed position to allow said expiratory flow to flow through said first outlet and into said exhalation membrane , causing it to expand until said peak pressure is reached, and once said peak pressure has been reached, said second valve and said third valve are in an open position while said first valve is in a closed position to allow the remaining expiratory flow to be redirected to said second outlet to create a positive end expiratory pressure, and to said third outlet which allows the air inside the exhalation membrane 3014 to escape out to atmosphere. an exhalation membrane pressurizable from a first pressure to a peak pressure; an exhalation chamber surrounding said exhalation membrane , wherein said exhalation membrane ) expands inside said exhalation chamber as said exhalation membrane is pressurized from said first pressure to said peak pressure; an expiratory flow path communicating with said exhalation membrane ; an inspiratory flow path communicating with said exhalation chamber; and at least one intake portal communicating with said exhalation chamber , characterized by a three way valve comprising a first valve , a second valve , and a third valve which are in communication with a first outlet , a second outlet , and a third outlet , respectively, said first valve connects the patient's expiratory flow to said exhalation membrane , said second valve connects the patient's expiratory flow to atmosphere, said third valve connects said exhalation membrane to atmosphere at a location spaced from said expiratory flow path , wherein said three way valve is configured such that said first valve is in an open position while said second valve and said third valve are in a closed position to allow said expiratory flow to flow through said first outlet and into said exhalation membrane , causing it to expand until said peak pressure is reached, and once said peak pressure has been reached, said second valve and said third valve are in an open position while said first valve is in a closed position to allow the remaining expiratory flow to be redirected to said second outlet to create a positive end expiratory pressure, and to said third outlet which allows the air inside the exhalation membrane 3014 to escape out to atmosphere. <EOS>