Philips Respironics V60, User Manual

Page: 59 / 212

Principles of operation
4-15
Oxygen mixing
The ventilator’s oxygen mixer regulates and proportions oxygen into the air
from the blower according to the O
2
setting. The delivered oxygen accuracy is
±5% of the set value up to the maximum oxygen flow available. The ventilator
can deliver up to 240 L/min of air/oxygen mix to assist in managing
uncontrolled leaks during noninvasive ventilation.
Many hospital oxygen supply systems, however, cannot meet such high flow
demands. Under extraordinary conditions (high O
2
setting plus high leak, and/
or high patient demand) where demand exceeds available oxygen system flow,
the ventilator provides additional air flow from the blower to ensure the target
pressure is met. Under such conditions, the accuracy of delivered oxygen may
be affected. Figure 4-16 shows the effect on the delivered oxygen
concentration as the maximum oxygen system flow is exceeded. This graph
assumes a continuous flow demand. Normally the higher “peak” flow is only
needed during inspiration, so this is a worst case scenario.
Figure 4-16: O
2
concentration as a function of total ventilator flow
40
45
50
55
60
65
70
75
80
85
90
95
100
130 140 150 160 170 180 190 200 210 220 230 240
Total Ventilator Flow L/min
O2
% C
oncentration
Assumptions: At an O
2
setting of 100% and an oxygen supply with a 50 psig inlet pressure capable
of delivering up to160 L/min.
Total ventilator flow (L/min)
Oxyg
en conc
e
ntration
(%)