Association between aging and in vivo mitochondrial oxygen tension (mitoPO2) and oxygen consumption (mitoVO2) in healthy volunteers.

The Cellular Oxygen METabolism (COMET^®) device provides validated bedside in vivo measurements of mitochondrial oxygen tension (mitoPO₂) and consumption (mitoVO₂). Because mitochondrial function has been shown in experimental in vivo and ex vivo studies to potentially alter with age, it is important to establish whether age itself influences these in vivo measurements. The aim of this single-center prospective observational study was to determine whether mitoPO₂ and mitoVO₂ values are influenced by age, thereby ensuring their validity for use across age groups. The aim of the study was not to evaluate COMET^® as monitor of aging. Using the COMET^® device, mitoPO₂ and mitoVO₂ were measured at the upper arm and sternum in 176 healthy participants aged 18-90 years. The mean arm mitoPO₂ was 75.3 ± 28.7 mmHg (mean ± SD), while the mean sternal mitoPO₂ was 65.8 ± 23.6 mmHg. Multivariable linear regression did not demonstrate a significant age-related change in mitoPO₂. Conversely, the mean arm mitoVO₂ was 6.37 ± 2.07 mmHgꞏs^-1, and the median sternal mitoVO₂ was 7.16 mmHgꞏs^-1 [IQR 5.63-9.17]. Multivariable linear models at both sites demonstrated a significant negative association between age and mitoVO₂. No significant sex differences were observed for either parameter. These findings reveal that while mitoPO₂ remains unaffected by age, mitoVO₂ shows a significant negative association with increasing age. This distinction suggests that mitoPO₂ can be interpreted independent of age, whereas mitoVO₂ requires age-informed consideration. By profiling healthy volunteers across four decades, we establish preliminary age-informed normative ranges for epidermal mitoPO₂ and mitoVO₂.