Prerecorded telemedicine.

In prerecorded telemedicine (also known as asynchronous or store-and-forward), the person sending the information and the person receiving it do not need to do so simultaneously; thus, viewing the information can be done at some later time. Prerecorded telemedicine is therefore not appropriate for emergency consultations. In prerecorded telemedicine systems, the following steps can be distinguished: (1) the acquisition of diagnostic information at the remote site; (2) its storage, which can be at either site, or at both; (3) its delivery to the expert site through an appropriate connection; and (4) its display at the expert site. The types of information transferred include audio, data and text, still images and moving images (i.e. video). An increasingly common way of doing prerecorded telemedicine is by email sent via the Internet. Although there are some problems associated with the Internet, its wide availability and low cost have encouraged its use. Examples where email has been used successfully include teleradiology, telecardiology, teledermatology and telepathology. In some situations prerecorded telemedicine is the only way to provide remote medical services, or the most cost-effective method. Clearly, there are also situations when prerecorded telemedicine is not an appropriate way to deliver health services, for example whenever the sender of the information is not qualified to sample the information acquired or the specialist receiving the information must manipulate it, during acquisition, in some way.