With the recent introduction of tissue plasminogen activator (t-PA) drugs, how has the standard of care changed for the E.R. physician in his/her treatment of a patient with symptoms of stroke (e.g. dizziness, vomiting, blurred vision, hypertension, lethargy and loss of awareness), but whose CT Scan is negative and desires to leave the E.R.? What is the standard of care both pre- and post-t-PA?
IV tPA is used for the treatment of ischemic strokes within three hours of onset, provided some very specific conditions are met. These include a precise history of the timing of onset, a certain degree of severirty of the stroke, a reliably interpreted negative CT head scan for a fresh infarct or a hemorrhage, blood pressure values below a certain limit, and exclusion of medical or surgical conditions that would put the patient at risk of dangerous hemorrhage.
IV tPA can be dangerous if used too late, or for too large a stroke, or in the presence of a CT scan showing signs of an early infarction. It would also be an unnecessary risk if the stroke is too mild, or rapidly improving, or if there is diagnostic uncertainty about the event.
The benefit of IV tPA is increasing modestly the number of patients that will eventually have a good outcome. Approximately a six percent risk of a
symptomatic brain hemorrhage is incurred when tPA is used, but this is acceptable because it is offset by the benefit. The risk - benefit equation is less favorable in the elderly.
As you would figure, only a small minority of cases of stroke reaching the ER receive tPA. Hence, although tPA may be considered a possible new standard of care, it is not as widely applicable as one might think due to numerous (at this time) uncontrollable factors. Also, it should not be thought of as a magic clot-busting bullet in its efficicy.