During the inhalation by the patient, the entrainment flow through the entrainment passage may substantially prevent the control gas from flowing across the entrainment passage so as to interrupt {HEAD ~ the delivery} of {TAIL ~ the control gas} to the fluid conduit 
During the inhalation by the patient , the entrainment flow through the entrainment passage may substantially prevent the control gas from flowing across the entrainment passage so as to interrupt { HEAD ~ the delivery } of { TAIL ~ the control gas } to the fluid conduit
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH