Room Air Readings of Brain Tissue Oxygenation Probes
Intracranial Pressure & Neuromonitoring XVI
Acta neurochirurgica Supplement, January 2018
Stefan Wolf, Ludwig Schürer, Doortje C. Engel
Brain tissue oxygenation (pbtO2) monitoring with microprobes is increasingly used as an important parameter in addition to intracranial pressure in acutely brain-injured patients. Data on accuracy and long-term drift after use are scarce. We investigated room air readings of used pbtO2probes for their relationship with the duration of monitoring, geographic location of the center, and manufacturer type. After finishing clinically indicated monitoring in patients, pbtO2probes used in two centers in Berlin and Munich were explanted and cleaned to avoid blood contamination. Immediately afterward, room air readings of partial oxygen pressure (pairO2) from 44 Licox®and 10 Raumedic®pbtO2probes were recorded. Assumed height above sea level was 42 m for Berlin and 485 m for Munich; this resulted in assumed theoretical pairO2readings of 157.8 mmHg in Berlin and 149.9 mmHg in Munich. Licox®probes in Berlin showed a mean pairO2of 160.5 (SD 14.4) mmHg and of 147.8 (11.9) mmHg in Munich. Raumedic®probes in Berlin showed a mean pairO2of 170.5 (12.2) mmHg and the single Raumedic®probe used in Munich 155 mmHg. No significant drift was found over time for probes with up to 14 days of monitoring. Prolonged use of up to 20 days showed a clinically negligible drift of 1.2 mmHg per day of use for Licox®probes.Mean absolute deviation for pairO2from expected values was 6.4% for Licox®and 9.7% for Raumedic®probes. Room air partial oxygen pressure pairO2may be utilized to assess the proper function of a pbtO2probe. It provides a tool for quality control which is easy to implement. Probe readings are stable in the clinically relevant range, even after prolonged use.
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