Implantable Transcranial Doppler
Sometimes a patient’s history and clinical signs suggest a very high risk of stroke. Occlusive stroke causes permanent tissue damage over the following three hours (maybe even 4.5 hours), but not instantly. Various drugs (e.g. aspirin, streptokinase, and tissue plasminogen activator (TPA) in ascending order of effectiveness and cost) can reverse the stroke process. The problem is how to know immediately that a stroke is happening. One possible way is the use of an implantable transcranial Doppler device "operatively connected to a drug delivery system". Battery-powered, it would use an RF link to a portable computer running a spectral analysis routine together with input from an oximeter (monitoring the degree of blood oxygenation, which a stroke might impair) to make the automatic decision to administer the drug.
Read more about this topic: Transcranial Doppler