Intensive Care Medicine (ICM) Practice Exam

Which of the following would not induce hypoxia?

1. Ischemia

2. Hypoxemia

3. Anemia

4. Hyperventilation

The correct answer is: Hyperventilation

The reason hyperventilation would not induce hypoxia lies in the physiological effects it has on oxygen levels in the blood. Hyperventilation leads to an increase in alveolar ventilation, which typically results in higher levels of oxygen being exchanged in the lungs and subsequently higher oxygen saturation levels in the arterial blood. This increase in ventilation is often accompanied by a decrease in carbon dioxide (CO2) levels (hypocapnia), but it does not directly reduce the amount of oxygen available; rather, it may enhance it. In contrast, the other options listed are conditions that can lead to hypoxia in various ways. Ischemia involves a lack of blood flow to tissues, thereby reducing oxygen delivery. Hypoxemia refers to low levels of oxygen in the blood, which can arise despite normal oxygen-carrying capacity. Anemia, characterized by a decrease in red blood cells or hemoglobin, reduces the blood's oxygen-carrying capacity, leading to tissue hypoxia even when oxygen saturation might appear normal. These three processes directly impact oxygen delivery or availability, while hyperventilation enhances respiratory function and typically increases oxygen levels, thus not inducing hypoxia.