Safety device for a blood treatment apparatus

摘要

The computer (29) determines a decreasing upper limiting value for ultrafiltration rate with increasing treatment duration or increasing ultrafiltration volume. An independent claim is included for the corresponding method of enhancing safety during blood treatment. Preferred features: The computer divides predetermined total ultrafiltration volume by treatment duration, to arrive at the mean ultrafiltration rate, required to extract this volume in given treatment time. Mean ultrafiltration rate is multiplied by a factor to determine the upper limiting value. Using this method, an equation (presented in the text) determines the upper limiting value to a set point in time. A further equation determines the residual ultrafiltration rate up to a set point in the remaining interval of treatment. By multiplying residual filtration rate by a factor, the upper limiting value can be determined to the point in time. An alarm (34) signals when the mean ultrafiltration rate is exceeded. An alarm is given on exceeding the upper limiting value of ultrafiltration rate. The monitoring unit (30) has a comparator, comparing the filtration rate predetermined by the control unit and a lower limiting boundary value. The monitoring unit is implemented such that ultrafiltration rates is held to the upper limiting value only when it exceeds the lower limiting value.