This study measured in vivo mitochondrial oxygen tension (mitoPo ₂ ) and consumption (mitoV̇o ₂ ). mitoPo ₂ remained constant across ages, this stability of mitoPO ₂ suggests consistent mitochondrial oxygen availability, eliminating the need for age-based adjustments in ongoing research using a low mitoPO ₂ threshold to predict adverse events such as cardiac surgery associated acute kidney injury. However, mitoV̇o ₂ significantly decreased with age, showing that age must be taken into account when interpreting mitoV̇o ₂ values and when defining reference ranges.

Deep Sedation (DS) allows for shorter recovery times, reduced complication rates and increased cost-effectiveness compared to general anesthesia. In prolonged DS, High Flow Nasal Oxygen Therapy (HFNOT) ensures adequate oxygenation. Concerns remain regarding potential masking of inadequate ventilation and induction of hyperoxia. In this single-center observational study, we continuously monitored tcPCO₂ and mitoPO₂ in 30 patients using the SenTec Monitoring System and Cellular Oxygen METabolism (COMET^®, Photonics Healthcare, Utrecht, The Netherlands) device to observe the effect of prolonged DS with HFNOT on periprocedural ventilation and oxygenation. Measurements were taken at baseline and 30, 60, 90 and 120 min after starting DS. tcPCO₂ significantly increased after 30 (55.5 (34.5–61.9) mmHg, p < 0.001), 60 (54.8 (52.5–62.2) mmHg, p < 0.001), 90 (56.5 (53.1–69.3), p < 0.001) and 120 (55.8 (50.7–56.6) mmHg, p = 0.02) minutes of DS compared to baseline (37.3 (34.5–45.5) mmHg), surpassing the normal range (35–45 mmHg). mitoPO₂ increased non-significantly from baseline (69.6 (43.9–76.7) mmHg) compared to 30 (80.5 (65.7–98.9) mmHg, p = 0.19), 60 (78.6 (70.3–85.8) mmHg, p = 0.19), 90 (74.4 (52.7–86.3) mmHg, p = 0.38) and 120 (85.6 (82.5–98.0) mmHg, p = 0.38) minutes. We observed increased tcPCO₂ and a non-significant rise in mitoPO₂ over time, without adverse effects. These findings highlight the potential of continuous sensor-based monitoring to improve real-time detection of ventilation and oxygenation.