Which of the following best describes a high V/Q ratio?

A high V/Q ratio indicates a condition where there is significant ventilation relative to perfusion in the lungs. This means that while there is a good amount of air getting to the alveoli (ventilation), the blood flow (perfusion) to those areas is limited or low. As a result, there is an imbalance that can lead to inefficiencies in gas exchange, specifically a reduced capacity for carbon dioxide removal and oxygen uptake. This is commonly seen in scenarios like pulmonary embolism, where a blockage in the blood vessels decreases blood flow to a well-ventilated area of the lung.

The description of well-matched ventilation and perfusion refers to a scenario where both ventilation and perfusion are optimized to facilitate effective gas exchange, which does not correspond to a high V/Q ratio. Low ventilation with high blood flow reflects the opposite condition, where there is insufficient air in the lungs to match the blood flow, thus indicating a low V/Q ratio. Finally, normal gas exchange occurs when V/Q ratios are balanced and optimal, which again does not describe a high V/Q ratio.