Table 1. Comparison of the oxygen gas (O₂) saturation and pH characteristics in aCSF perfusate using the external oxygenator and in-bore oxygenator systems.

	pH	Dissolved O2
aCSF Reservoir Negative Control (Equilibrated to Atmosphere)	8.22 ± 0.016	23.02 ± 0.08%
aCSF Reservoir Positive Control (direct bubbled 95% O2, 5% CO2)	7.36 ± 0.018	95.54 ± 0.97%
External Membrane Oxygenator	8.13 ± 0.085	43.43 ± 3.52%
In-Bore Membrane Oxygenator	7.32 ± 0.019	96.18 ± 1.87%

Measurements for the external and in-bore oxygenator configurations were taken in the perfusion chamber. When employing the external oxygenator, loss of dissolved CO₂ (degassing) from perfusion lines resulted in an excessively alkaline aCSF mixture at the site of tissue perfusion. Similar pH conditions were closely replicated in an untreated aCSF reservoir left exposed to atmospheric air (negative control). Use of the in-bore oxygenator restored CO₂ levels in the bicarbonate-buffered aCSF perfusate as evidenced by a return to physiologically relevant pH values. Compared to positive control measurements, aCSF gassed by the external oxygenator exhibited a 54.3% drop in total dissolved oxygen content between the oxygenator and perfusion chamber. When employing the in-bore oxygenator, no measurable loss of dissolved oxygen was noted. pH testing (n = 8), dissolved O₂ testing (n = 10 [control & external], n = 6 [in-bore]). Values are reported as group averages ± standard deviation.