42 CFR §409.14

1. (a)Except as specified in paragraph (b) of this section, Medicare pays for supplies, appliances, and equipment as inpatient hospital or inpatient CAH services only if—
   1. (1)They are ordinarily furnished by the hospital or CAH to inpatients; and
   2. (2)They are furnished to inpatients for use in the hospital or CAH.
2. (b)Exceptions. Medicare pays for items to be used beyond the hospital or CAH stay if—
   1. (1)The item is one that the beneficiary must continue to use after he or she leaves the hospital or CAH, for example, heart valves or a heart pacemaker, or
   2. (2)The item is medically necessary to permit or facilitate the beneficiary's departure from the hospital or CAH and is required until the beneficiary can obtain a continuing supply. Tracheostomy or draining tubes are examples.