A closure device (10) is disclosed for use with an access port (62,72,82,92) of a medical respiratory apparatus (60,70,80,90). The closure device (10) comprises a cap (14) that seals the access port (62,72,82,92) save for an opening (28) in the cap (14), and a closure (16) for sealing the opening (28). The cap (14) includes a portion of flexible material (26) in which the opening (28) is formed, and is hingedly mounted with respect to the access port (62,72,82,92).