A lesion is any abnormal damage or change in the tissue of an organism, usually caused by disease or trauma. Lesion is derived from the Latin word laesio meaning injury. Lesions may occur in plants as well as animals.
These first six months are known as the length-of-stay demonstration period. After maintaining a Medicare ALOS of 25 days for six months, Landmark Hospital applies to CMS for a change in provider status and receives a LTAC-hospital Medicare provider number.
Once this is started, LTOT is likely to be lifelong. It is usually given over a minimum of 15 hours a day, including overnight when arterial hypoxaemia worsens during sleep (some advocate 18 or even 24 hours a day). See also the separate article on Prescribing Oxygen.