Certified Pediatric Emergency Nurse (CPEN) Practice Exam

What is the primary cause of tissue hypoxia in cases of carbon monoxide poisoning?

1. Inadequate blood flow

2. High carbon dioxide levels

3. Oxygen deficiency in the air

4. Inadequate oxygen transport

The correct answer is: Inadequate oxygen transport

The primary cause of tissue hypoxia in cases of carbon monoxide poisoning is inadequate oxygen transport. Carbon monoxide binds to hemoglobin with a much higher affinity than oxygen does, forming carboxyhemoglobin. This binding reduces the amount of hemoglobin available for oxygen transport, leading to a decreased supply of oxygen to the tissues despite potentially normal levels of oxygen in the air. As a result, even if an individual breathes adequate oxygen, their body cannot effectively utilize it because the hemoglobin is occupied by carbon monoxide, resulting in tissue hypoxia. While inadequate blood flow, high carbon dioxide levels, and oxygen deficiency in the air can contribute to hypoxia in various scenarios, they are not the primary mechanism in carbon monoxide poisoning. In this situation, the critical factor is the impaired capacity of hemoglobin to carry oxygen due to the presence of carbon monoxide. Understanding this mechanism is crucial for effective recognition and treatment of carbon monoxide poisoning in a pediatric emergency setting.