2006 OPEN FORUM Abstracts
EVALUATION OF OXYGEN BLEED-IN LOCATION DURING CPAP WHEN USING AN ELECTRONIC BREATHING SIMULATOR
Ty Barnett, Eric Peart,
Lutana
Haan
RRT.
Boise
State
University
,
Boise
,
ID.
Background: Home-use CPAP machines deliver set
pressures, entraining room air at 21% O2. If supplemental O2 is
needed to maintain O2 saturation, it can be bled into the circuit through
built-in ports at the mask, or into a t-piece close to the machine. The effect
of bleed-in location was evaluated with two different masks, at four different
O2 liter flowrates and four different levels of CPAP.
Method: A ResMed
VPAP III was interfaced with a standard
6 foot circuit to a mask placed on a mannequin that was attached to the Hans
Rudolph Electronic Breathing Simulator (HR 1101). The HR 1101 settings:
resistance 5 cm H2O/L/sec; compliance 40 mL/cm H2O; respiratory
rate 15 breaths per minute. ResMed settings: CPAP 5,
10, 15 and 20 cm H2O. Oxygen flowrates: 1, 3, 6 and 8 LPM. Masks
used: ResMed Ultra Mirage FF and Respironics Comfort
Full.
Results: At oxygen flowrates of 1, 3, 6 and 8 LPM, the O2 percentage was as follows: the ResMed Ultra
Mirage FF, at 5 cm H2O with O2 bled in at the mask was 22, 23.5, 26 and 27%,
and at the machine was 22, 24, 27 and 29%; at 10 cm H2O with O2 bled in at the mask was 22, 22.5, 24.5 and
26%, and at the machine was 22, 23, 25.5 and 27%; at 15 cm H2O with O2 bled in at the mask was 22, 23, 24 and 25%,
and at the machine was 22, 23, 25 and 26%; at 20 cm H2O with O2 bled in at the mask was 22, 23, 24.5 and
25.5%, and at the machine was 22, 23, 24.5 and 25.5%; the Respironics Comfort Full 2 at 5 cm H2O
with O2 bled in at the mask was 21.8, 22.8, 24.8 and
25.5%, and at the machine was 22, 23, 25 and 26.5%; at 10 cm H2O with O2 bled in at the mask was 22, 22.5, 23.5 and
24.5%, and at the machine was 22, 22.8, 24 and 25%; at 15 cm H2O
with O2 bled in at the mask was 22, 23, 24 and 25%, and
at the machine was 22, 23, 24 and 25%; at 20 cm H2O with O2 bled in at the mask was 22, 23, 24 and 25%,
and at the machine was 22, 23, 24.8 and 25.5%.
Conclusion: Bleed-in location does affect the delivered
O2. Oxygen flowrates, mask selection and pressure levels also affect
the delivered O2. Oxygen should be monitored carefully when
CPAP is applied to patients with different interfaces.