{HEAD ~ The apparatus} 11, wherein {TAIL ~ said gas delivery system} comprises a face mask coupled to a flexible conduit 
{ HEAD ~ The apparatus } 11 , wherein { TAIL ~ said gas delivery system } comprises a face mask coupled to a flexible conduit
HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH