The software algorithm to analyze hemodialysis data is accessible via a secure, password protected (HIPAA compliant) Internet-based system. Centers automatically upload the treatment data generated each day to the Vasc-Alert site via a secure connection. The data is processed and the results are stored in a patient's history file. If the facility is not 'wired' (i.e., their HD machines are not connected to a central computer), the data can be entered manually over the Internet or into a spreadsheet for transmittal. In this case, it is only necessary to input five sessions per month to provide sufficient screening of patients for stenosis.

If the result for a patient on a given day is equal to or above 0.55, the previous two sessions for the patient are examined from the history file. If all three sessions are above the trigger limit of 0.55, Vasc-Alert generates an alert report. These reports are sent out by e-mail or fax on a weekly basis. A summary report, covering all patients in the center, is sent out monthly. These reports are typically sent to the access coordinator who will, in consultation with the medical staff, determine if the patient should be referred for intervention.

Figure 2: Overview of the Vasc-Alert information flow