XVIVO Perfusion System (XPS
TM
) Instructions for Use
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55
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P/N: 9182
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0189 Revision Q
4.4.3 Low pH
Low pH is a well
-
described phenomenon in
isolated lung perfusion. Lung tissue carries
out an important metabolic activity. Studies
with isolated lung perfusion have shown that
the majority of the glucose is metabolized
through the glycolytic pathway to pyruvate
and lactate. The distribution between pyruvate
and lactate depends on the redox state of the
cells, but in steady state, lactate production is
10 times higher than pyruvate.
Interventions include:
Adjust the deoxygenation gas flow rate
down to effectively clear CO
2
(Sec 4.3.2).
Administer Trometamol (THAM) buffer:
1mL (of 1 Molar concentration) for each nega-
tive mmol base excess.
Replace complete volume (~1,500cc) of
STEEN Solution
TM
with fresh STEEN Solution
TM
(sec 2.4.2).
NOTE: If the gas flow adjustment is not suffi-
cient to normalize pH, careful buffering with a
suitable buffer such as sodium bicarbonate or
THAM is recommended. It is important to
make the adjustment based on the actual pH
and to use an iterative process to titrate the
pH to the relevant value using pH analysis on a
blood gas analyzer between each step of ad-
justment.
NOTE: Repeated administration of sodium bi-
carbonate is not recommended. This tends to
increase the perfusate sodium concentration
causing capillary constriction and elevation of
the PVR.
Troubleshooting
4.4.4 Low PCO
2
PCO
2
should be maintained between 35
-
45mmHg.
Interventions include:
Increase PCO
2
by increasing deoxygen gas.
Decrease PCO
2
by decreasing deoxygen gas.
Alternatively, expiratory ratio can be adjust-
ed to control PCO
2
.
