Final answer:
A PaO2 of 58 mm Hg indicates that the oxygen level in the blood is lower than normal, suggesting impaired gas exchange and potential respiratory issues. It is important to monitor and address the oxygenation status in such scenarios.
Step-by-step explanation:
The question relates to the partial pressure of oxygen, commonly referred to as PaO2, in the blood. A partial pressure of PaO2 58 mm Hg suggests that the oxygen level in the blood is lower than the normal range, which is around 75 to 100 mm Hg for a healthy individual. The external air has a much higher partial pressure of oxygen, approximately Po₂ = 150 mm Hg, which allows for oxygen to flow from the lungs into the bloodstream at a high gradient when breathing normally. However, in the alveoli of the lungs, due to mixing with residual air and other factors, the alveolar Po₂ is lower.
In the systemic capillaries, blood has a Po₂ of 100 mm Hg, while tissue cells have a Po₂ of 40 mm Hg. This gradient facilitates the diffusion of oxygen into tissue cells. Similarly, the capillary blood CO2 pressure (Pco₂) of 45 mm Hg compared to the tissue cells' 40 mm Hg allows carbon dioxide to diffuse out of the cells into the blood.
Fundamentally, a PaO2 of 58 mm Hg would decrease the efficiency of oxygen transfer from the alveoli to blood, affecting oxygen delivery to the tissues. This can be deleterious and could signal respiratory issues that require medical attention. Monitoring and possibly increasing oxygenation would likely be important steps the nurse should expect to take.