Respiratory acidosis occurs when there is an excessive accumulation of carbon dioxide (CO2) in the bloodstream, typically due to inadequate respiration which can be caused by various factors such as chronic obstructive pulmonary disease (COPD), airway obstruction, or respiratory depression. When CO2 levels exceed 60 mmHg, this indicates that the body is not effectively removing CO2, leading to an increase in carbonic acid in the blood and subsequent decrease in blood pH (acidosis).
In contrast, metabolic acidosis is characterized by a decrease in bicarbonate levels or an increase in non-carbonic acids independent of CO2 levels. Hypoxemic acidosis can occur due to low oxygen levels but is not specifically defined as a result of increased CO2. Mixed acidosis refers to the presence of both respiratory and metabolic acidosis simultaneously, which would not be the case strictly defined by CO2 levels alone. Thus, elevated CO2 levels above 60 mmHg primarily indicate respiratory acidosis due to its direct relationship with carbon dioxide retention and acid-base balance disruption.