Title: Final Test 8500
Document No: 129TP000
Sheet 15 of 17
BLEASE QUALITY DOCUMENT
BQD 083.V2
25/5/94
Checked:-________
6.0 USING THE CALIBRATION ANAYSER
This section is intended to be guide in using the Calibration Analyser with this test procedure.
It should be read in conjunction with the operating manual supplied with the Calibration
Analyser.
6.1 Volume Measurement Correction
For volume measurements, the patient circuit is connected as shown in section 6.4, that is,
with compliance connected to the High Flow Outlet of the Calibration Analyser. In this
configuration, all Calibration Analyser volume measurements MUST HAVE A
CORRECTION FIGURE ADDED TO THE INDICATED VALUE.
A simple correction formulae is:
At 500 ml
≈
25cm H
2
O peak pressure
∴
mean pressure
≈
12.5
Calibration Analyser reads 0.48 Lpm
Actual = (0.48 x (1+0.0125)) = 0.486 Lpm
Where MEAN PRES is the breath mean pressure in cm H
2
O while there is measurable flow.
This formulae must be applied to ALL the Calibration Analyser volume readings BEFORE
they are written on the Checklist and Calibration Record.
For example, given an indicated volume of 1.13 Litres and a mean breath pressure of 30
cmH
2
O. The actual volume would be:
= 1.13 ( 1 + 30/1000) = 1.13 x 1.03 = 1.16 Litres
Timeter specific information
For other analysers consult their operating manual.
The breath mean pressure need only be accurate to ± 5 cm H
2
O and could be obtained
directly from the ventilators own pressure display. Alternately, Function Code 12 with the
Peak Special Function could be selected on the Timeter to obtain the peak breath pressure. A
ventilator supplying a constant gas flow produces a linear ramp change in pressure, hence
the mean pressure is approximately half the peak pressure. (Normally a few cm H
2
O more
due to compliance effects on pressure waveform.)