What is one of the immediate effects of V/Q mismatch on oxygen levels?

V/Q mismatch refers to an imbalance between the ventilation (air reaching the alveoli) and perfusion (blood flow to the alveoli) in the lungs. When this mismatch occurs, one of the immediate physiological effects is a decrease in arterial oxygen tension, or the pressure of oxygen in the arterial blood. This happens because, in areas of the lung where ventilation is poor, oxygen cannot adequately enter the blood due to insufficient air, leading to lower oxygen levels in the bloodstream. Additionally, even if blood flows to well-ventilated areas of the lung, the overall efficiency of gas exchange is compromised due to the mismatch, ultimately resulting in reduced arterial oxygen levels. This immediate response can lead to hypoxemia, where the body tissues receive less oxygen than needed, adversely affecting overall oxygenation.