What does a low PaO2 and high PaCO2 indicate?

A low PaO2 (partial pressure of oxygen) combined with a high PaCO2 (partial pressure of carbon dioxide) indicates respiratory failure. This condition typically arises when the lungs are unable to adequately ventilate or exchange gases. In respiratory failure, the alveoli are not effectively exchanging oxygen and carbon dioxide, leading to hypoxemia (low oxygen levels) and hypercapnia (high carbon dioxide levels).

This scenario often occurs in conditions such as chronic obstructive pulmonary disease (COPD) or severe asthma exacerbations, where airway obstruction can impede gas exchange. It illustrates the body's inability to maintain proper blood gas levels due to compromised lung function, resulting in inadequate oxygenation and a build-up of carbon dioxide in the bloodstream.

Understanding the significance of these measurements is crucial for recognizing and managing respiratory failure effectively.