METRON QA-IDS, Руководство пользователя и обслуживания

Страница: 23 / 62

4. Infusion Pump Testing
This chapter details procedures for conducting each of the QA-IDS
tests.
4.1 Introduction
Infusion pump testers calculate flow rates from a measured time pe-
riod to fill a defined volume. If it takes one hour to fill a defined
volume of 10 milliliters, the flow rate is calculated to be 10 ml/hr.
This flow rate is called the instant flow rate. The minimum volume
detection of this measurement is 10 milliliters, since it needs that
amount to calculate a flow rate. The next instant flow rate calcula-
tion may be done when an additional volume of 10 ml is delivered
to the measuring device. When two or more instant flow rates have
been obtained, the calculation of a
mean flow rate can be done by
averaging the instant flow rates.
Detecting unexpected flow changes requires detection of tiny infu-
sion volumes, as flow measurements may only be calculated every
time the defined volume is filled up. The ability to detect small infu-
sion volume requires that measurements be made frequently, hence
a high flow-sampling rate. The ability to detect only larger infusion
volumes decreases the sampling rate, as well as the ability to accu-
rately detect flow changes. International standards prescribe flow
sampling to be done every thirty seconds for all flow rates to ensure
a steady rate of infusion from all types of infusion devices. To fulfill
this requirement, minimum volume detection of the measuring de-
vice is critical.
Example:
To test an infusion pump for unexpected flow changes at a flow rate
of 10 ml/hr, with an accuracy of ± 2%, the following minimum flow
detection is needed:
Expected flow: 10 ml/hr = 166.7 pl pr. minute (divide by 60) = 83.3 µl
pr. 30 sec. (divide by 2).
2% of expected flow: 83.3 µl pr. 30 sec. x 2% = 1.67 µl pr. 30 sec.
A volume detection of 1.67 µl is required to detect a 2% unex-
pected, sudden flow change from an expected flow rate of 10 ml/hr
within 30 seconds.
The minimum volume detection of QA-IDS is 0.72 µl. That means
that less than 1 µl is needed for QA-IDS to detect any sudden flow
change between 0.10 ml/hr and 1000.0 ml/hr. QA-IDS performs
flow-samplings every second for all flow rates.
4.2 Test Preparation
23