Final answer:
Administering 100 percent oxygen to patients with carbon monoxide poisoning provides a high concentration of oxygen, which outcompetes carbon monoxide at the hemoglobin binding sites, reversing the effects of poisoning. Carbon dioxide is not used because it does not affect the binding of carbon monoxide to hemoglobin, nor does it assist in oxygen transportation. Partial pressure of oxygen influences oxygen binding to hemoglobin, critical for oxygen transport to tissues.
Step-by-step explanation:
Administering 100 percent oxygen to a patient can save them from carbon monoxide poisoning because oxygen competes with carbon monoxide for binding sites on hemoglobin, the molecule in red blood cells that transports oxygen. Carbon monoxide binds to hemoglobin much more tightly than oxygen, reducing the blood's oxygen-carrying capacity and causing tissue hypoxia. By providing a high concentration of oxygen, it is more likely that oxygen will bind to any free binding sites, displacing carbon monoxide and allowing normal oxygen transport to resume. Giving carbon dioxide would not work because it does not compete with carbon monoxide for binding sites on hemoglobin and has no ability to displace carbon monoxide or carry oxygen.
Furthermore, the relationship between the partial pressure of oxygen and the binding of oxygen to hemoglobin is such that increased partial pressure enhances oxygen binding to hemoglobin. This allows efficient oxygen transport to body tissues. In contrast, carbon dioxide is transported from tissue to lungs via three methods: dissolved in plasma, as bicarbonate, and bound to proteins, including hemoglobin, but not competing for the same binding sites as oxygen.