What is the initial arterial blood gas finding in a pulmonary embolism?

In the case of a pulmonary embolism, the initial arterial blood gas finding is respiratory alkalosis. This occurs primarily due to the hypoxemia (low blood oxygen levels) that results from the obstruction of blood flow to the lungs. As the body attempts to compensate for the lack of oxygenation, it leads to hyperventilation in an effort to increase oxygen intake. This hyperventilation causes the rate of carbon dioxide (CO2) exhalation to increase, resulting in a decrease in the partial pressure of carbon dioxide in the blood, which subsequently raises the blood pH and leads to respiratory alkalosis.

Therefore, the presence of respiratory alkalosis as the initial finding in a pulmonary embolism is indicative of the body's compensatory response to hypoxia, making it the correct answer to this question.