Final answer:
A non-rebreather mask delivers approximately 90% to 95% oxygen, not 100%. The answer choice closest to this range is 90%. Administering 100% oxygen is critical for treating carbon monoxide poisoning because it displaces carbon monoxide from hemoglobin.
Step-by-step explanation:
The percentage of oxygen delivered by a non-rebreather mask typically ranges from 90% to 100%. Generally, it is understood that a non-rebreather mask can deliver approximately 90% to 95% if used correctly instead of 100% due to some amount of mixing with room air and the fact that the mask does not form a complete seal against the face. However, 100% oxygen is often spoken of in a theoretical sense to denote the oxygen purity in the reservoir bag attached to the mask. Therefore, the correct answer among the given choices would be 90%.
Administering 100 percent oxygen is crucial in treating carbon monoxide poisoning because it competes with carbon monoxide for binding sites on the hemoglobin molecule. Since oxygen has a higher affinity for hemoglobin than carbon monoxide, providing a high concentration of oxygen can help to displace carbon monoxide from hemoglobin, thereby freeing up those binding sites. Giving carbon dioxide would not work as it does not compete with carbon monoxide for the same binding sites and does not aid in oxygen transportation needed for cellular respiration.