Mitochondrial Oxygenation During Cardiopulmonary Bypass: A Pilot Study

Floor A Harms; Rinse Ubbink; Calvin J de Wijs; Max P Ligtenberg; Maarten Ter Horst; Egbert G Mik

doi:10.3389/fmed.2022.785734

Mitochondrial Oxygenation During Cardiopulmonary Bypass: A Pilot Study

Front Med (Lausanne). 2022 Jul 18:9:785734. doi: 10.3389/fmed.2022.785734. eCollection 2022.

Authors

Floor A Harms¹, Rinse Ubbink¹, Calvin J de Wijs¹, Max P Ligtenberg¹, Maarten Ter Horst¹, Egbert G Mik¹

Affiliation

¹ Department of Anesthesiology, Erasmus Medical Center, Erasmus University Rotterdam, Rotterdam, Netherlands.

Abstract

Objective: 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^® monitor could be a tool to monitor oxygenation by measuring the cutaneous mitochondrial oxygen tension (mitoPO₂). This pilot study examines the feasibility of cutaneous mitoPO₂ measurements during cardiothoracic procedures. Cutaneous mitoPO₂ will be compared to tissue oxygenation (StO₂) as measured by near-infrared spectroscopy.

Design and method: 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 mitoPO₂ measurements. After induction of anesthesia, both cutaneous mitoPO₂ and StO₂ were measured throughout the procedure. The patients were observed until discharge for the development of acute kidney insufficiency (AKI).

Results: Cutaneous mitoPO₂ was successfully measured in all patients and was 63.5 [40.0-74.8] mmHg at the surgery start and decreased significantly (p < 0.01) to 36.4 [18.4-56.0] mmHg by the end of the CPB run. StO₂ 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 mitoPO₂ decrease of 7 mmHg (p < 0.01). The cessation of the aortic cross-clamping period resulted in an increase of 4 mmHg (p < 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 mitoPO₂ value under 20 mmHg as compared to 8% in the non-AKI group.

Conclusion: This pilot study illustrated the feasibility of measuring cutaneous mitoPO₂ using the COMET^® monitor during cardiothoracic procedures. Moreover, in contrast to StO₂, mitoPO₂ decreased significantly with the increasing CPB run time. Cutaneous mitoPO₂ also significantly decreased during the aortic cross-clamping period and increased upon the release of the clamp, but StO₂ did not. This emphasized the sensitivity of cutaneous mitoPO₂ to detect circulatory and microvascular changes.

Keywords: acute kidney injury; cardiopulmonary bypass and maze procedure; ischemia; microcirculation; mitochondria; mitochondrial oxygenation.