TcPO₂ changes are more pronounced than SpO₂ changes during simulated altitude changes in a hypobaric oxygen chamber: a nonrandomized controlled trial

Abstract

Background: Hypoxia is a significant risk factor of hypertension. However, no studies have used transcutaneous tissue partial pressure of oxygen (TcPO₂) and partial pressure of carbon dioxide (TcPCO₂) monitors to measure the respective partial pressures in healthy individuals. Oxygen saturation (SpO₂) is often used for traditional monitoring of vital signs. This study investigated the changes in TcPO₂ and SpO₂ values during rapid changes in altitude. The trial was registered at ClinicalTrials.gov (registration no. NCT06076057).

Methods: Healthy adult volunteers were instructed to sit vertically in a hypobaric oxygen chamber, which ascended from 0 m to 2500 m at a uniform speed within 10 min. The Danish Radiometer TCM4 was used to measure TcPO₂ and TcPCO₂ with the ventral side of the upper arm as the measurement site. The Shenzhen Kerokan P0D-1 W pulse oximeter was used to measure heart rate and SpO₂, with values recorded once every 500 m.

Results: Altogether, 49 healthy volunteers were recruited between March 2023 and August 2023. With increasing altitude, TcPO₂ and SpO₂ decreased significantly (P < 0.01). During the ascent from 0 m, TcPO₂ began to change statistically at 500 m (P < 0.05), whereas SpO₂ began to change statistically at 1000 m (P < 0.05). At the same altitude, the difference in TcPO₂ was greater than the difference in SpO₂. At 1000 m, there were statistically significant changes in TcPO₂ and SpO₂ (P < 0.001). At altitudes >500 m, statistical significance was identified between TcPO₂ in both sexes (P < 0.05). Statistical significance in TcPCO₂ and heart rate was observed at the different elevations (P < 0.05).

Conclusion: In acutely changing low-pressure hypoxic environments, TcPO₂ changed more dramatically than SpO₂.

Keywords

Altitude change / Low-pressure oxygen chamber / Transcutaneous oxygen saturation / Transcutaneous partial pressure of oxygen

Conflict of interest statement

The authors declare no conflict of interest.

Author contributions

Li Y, Chen L, Luan X, and Ma D participated in research design. Li Y, Chen L, Fu Z, and Wang Z participated in the writing of the paper. Li Y and Fu Z participated in the performance of the research. Chen L, Sun S, and Hu T contributed new reagents or analytic tools. Li Y, Fu Z, and Wang Z participated in data analysis.

Funding

This study was supported by grants from Shandong Province Key R&D Program (2021CXGC011301).

Ethical approval of studies and informed consent

All procedures performed in this study involving human participants were in accordance with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards. The trial was approved by Ethics Committee on Scientific Research of Shandong University Qilu Hospital (no. KYLL-202209-041, 2022.11.29). Written informed consent was obtained from all participants included in the study.

Acknowledgments

None.

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