Arena Service Manual
12.2 TRANSMEMBRANE PRESSURE
Transmembrane pressure is the hydrostatic pressure difference
inside the dialyzer across the membrane from the blood side to the
dialysate side.
“Venous pressure minus dialysate pressure” is the approximation
used to determine the TMP that is displayed on the Instrument
screen. Refer to Figure 12-10 for a TMP block diagram and to
Section 4.2.13 for the location of the dialysate pressure transducer.
During the Standby, Rinse and Prime Modes, the TMP alarm
limits are ±290 mmHg (within the range from technician set low
alarm limit (Section 17.3.1.11) to +500 mmHg) for approximately
100 seconds after the Blood Pump (BP) is turned on, BP or UF rate
is changed, the level adjust pump is operated, or the RESET button
is touched.
When the Dialyze Mode is started, the blood pump is started, the
blood pump is manually turned off, the blood pump rate changed,
or the UF rate is changed, the TMP alarm limits open to a 580
mmHg span within the range of the service technician-set lower
alarm limit to +500 mmHg for approximately 100 seconds. After
the 100 seconds, the alarm limits automatically set to ±35 mmHg
of the indicated TMP (repositioning the alarm window as
required). The TMP alarm limits may be manually set to ±35
mmHg of the indicated pressure by touching the SET LIMITS
button.
During the Dialyze Mode, when a level adjust button pushed or the
RESET button touched, the TMP alarm limits open. After 100
seconds the TMP alarm limits close maintaining the previous
alarm window position.
12-12 157-1278-919 Rev A
April 2004
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