Early diagnosis of human life support fundamentally depends on dissolved oxygen in the arterial microvasculature. This study used respiratory and pressure data to noninvasively estimate the partial pressure of oxygen in the radial artery. Usually, the PaO2 sample analysis is an episodic action, and timely correction of hypoxemia requires convenient and accurate arterial monitoring of the arterial PaO2. Analysis of the blood samples confirmed that the proposed sensor fusion method has an average estimation error of 1.77 mm Hg of PaO2. The experiment duration was one hour and 46 minutes, and at the end of the trial, the bias fluctuation of estimation was about one mmHg of PaO2 when matched with the offline blood sample results. The sensor fusion approach involved the occasional 129.06 millibars of ambient overpressure applied to the human body. The preclinical trial also demonstrated the therapy effect that even relatively small overpressure, excluding head area, has a noticeable therapy effect when the healthy patient continuously inhales the 15-16% oxygen concentration air for one hour and 30 minutes. The investigation results are relevant for operating invasive and noninvasive lung ventilation and treating the current pandemic patients.