Interpreting Data In The Clinical Menu - ResMed S8 Elite Manuel

338210r3 Eng.book Page 34 Monday, July 11, 2005 1:28 PM
I
NTERPRETING
Note: When assessing results, check the leak data first. Leak values greater than 0.4 L/s
(24 L/min) affect the accuracy of other measurements.
P
RESSURE
The pressure transducer located in the device measures treatment pressure; the
average pressure is calculated and recorded each minute. The pressure reported in the
Efficacy Data submenu (see Figure 7, The clinical menu results series, on page 32) for
a single session is the 95th centile pressure for mask-on time, excluding periods when
the leak has exceeded 0.4 L/s (24 L/min). For selected time intervals (last week, last
month, last six months, or last year), the median of the daily 95th centile values is
reported. Non-usage days are not included in calculations.
L
EAK
Leak is derived by analyzing inspiratory and expiratory airflows (via the flow sensor
located in the device). Theoretically, inspiratory and expiratory volumes should be
equal. A net airflow greater than the expected mask vent flow is equal to the leak.
Generally, a leak rate of more than 0.4 L/s (24 L/min) is associated with patient
discomfort, disturbed sleep, and reduced efficacy of treatment.
Notes:
a. If the leak exceeded 0.4 L/s (24 L/min) for more than 30% of the previous session, the
following message will appear on the LCD:
b. The Leak Alert feature, if enabled, will alert the patient when mask leak exceeds
0.7 L/s (42 L/min) for more than 20 seconds.
The leak reported in the Efficacy Data submenu (see Figure 7, The clinical menu results
series, on page 32) is the 95th centile value for mask-on time for each session, or the
median 95th centile value for a selected time interval (last week, last month, last 6
months, or last year). Non-usage days are not included in calculations.
APNEAS AND HYPOPNEAS
An apnea is defined as a greater than 75% decrease in ventilation. The device
algorithm scores an apnea if the 2-second moving average ventilation drops below 25%
of the recent time average (time constant 100 seconds) for at least 10 consecutive
seconds. A hypopnea is defined as a 50 to 75% drop in ventilation. A hypopnea is
scored if the 8-second moving average ventilation drops below 50%, but not below
25%, of the recent average for 10 consecutive seconds.
The AHI, AI, and HI reported in the Efficacy Data submenu are calculated values per
usage hour per session, or median values for a selected time interval (last week, last
month, last six months, or last year).
Note: When EPR is enabled, detection of apneas and hypopneas may become less
reliable at high levels of leak (> 0.4 L/s — 24 L/min).
34
D C
ATA IN THE LINICAL
M
ENU
High leak in last session
.