AUTHOR=Harms Floor A. , Ubbink Rinse , de Wijs Calvin J. , Ligtenberg Max P. , ter Horst Maarten , Mik Egbert G. 

TITLE=Mitochondrial Oxygenation During Cardiopulmonary Bypass: A Pilot Study

JOURNAL=Frontiers in Medicine

VOLUME=9

YEAR=2022

URL=https://www.frontiersin.org/journals/medicine/articles/10.3389/fmed.2022.785734

DOI=10.3389/fmed.2022.785734

ISSN=2296-858X

ABSTRACT=<sec><title>Objective</title><p>Adequate oxygenation is essential for the preservation of organ function during cardiac surgery and cardiopulmonary bypass (CPB). Both hypoxia and hyperoxia result in undesired outcomes, and a narrow window for optimal oxygenation exists. Current perioperative monitoring techniques are not always sufficient to monitor adequate oxygenation. The non-invasive COMET<sup>®</sup> monitor could be a tool to monitor oxygenation by measuring the cutaneous mitochondrial oxygen tension (mitoPO<sub>2</sub>). This pilot study examines the feasibility of cutaneous mitoPO<sub>2</sub> measurements during cardiothoracic procedures. Cutaneous mitoPO<sub>2</sub> will be compared to tissue oxygenation (StO<sub>2</sub>) as measured by near-infrared spectroscopy.</p></sec><sec><title>Design and Method</title><p>This single-center observational study examined 41 cardiac surgery patients requiring CPB. Preoperatively, patients received a 5-aminolevulinic acid plaster on the upper arm to enable mitoPO<sub>2</sub> measurements. After induction of anesthesia, both cutaneous mitoPO<sub>2</sub> and StO<sub>2</sub> were measured throughout the procedure. The patients were observed until discharge for the development of acute kidney insufficiency (AKI).</p></sec><sec><title>Results</title><p>Cutaneous mitoPO<sub>2</sub> was successfully measured in all patients and was 63.5 [40.0–74.8] mmHg at the surgery start and decreased significantly (<italic>p</italic> &lt; 0.01) to 36.4 [18.4–56.0] mmHg by the end of the CPB run. StO<sub>2</sub> at the surgery start was 80.5 [76.8–84.3]% and did not change significantly. Cross-clamping of the aorta and the switch to non-pulsatile flow resulted in a median cutaneous mitoPO<sub>2</sub> decrease of 7 mmHg (<italic>p</italic> &lt; 0.01). The cessation of the aortic cross-clamping period resulted in an increase of 4 mmHg (<italic>p</italic> &lt; 0.01). Totally, four patients developed AKI and had a lower preoperative eGFR of 52 vs. 81 ml/min in the non-AKI group. The AKI group spent 32% of the operation time with a cutaneous mitoPO<sub>2</sub> value under 20 mmHg as compared to 8% in the non-AKI group.</p></sec><sec><title>Conclusion</title><p>This pilot study illustrated the feasibility of measuring cutaneous mitoPO<sub>2</sub> using the COMET<sup>®</sup> monitor during cardiothoracic procedures. Moreover, in contrast to StO<sub>2</sub>, mitoPO<sub>2</sub> decreased significantly with the increasing CPB run time. Cutaneous mitoPO<sub>2</sub> also significantly decreased during the aortic cross-clamping period and increased upon the release of the clamp, but StO<sub>2</sub> did not. This emphasized the sensitivity of cutaneous mitoPO<sub>2</sub> to detect circulatory and microvascular changes.</p></sec>