Final answer:
Respiratory acidosis occurs when there is an excess of carbonic acid or CO₂ causing a lower than normal pH in the blood. It's diagnosed with a pH below 7.35 and elevated pCO₂ levels. Asthma can contribute to such acidosis by reducing the lungs' capability to expel CO₂.
Step-by-step explanation:
Respiratory acidosis is characterized by a decrease in blood pH due to an excess of carbonic acid or an increase in CO₂ levels, which leads to the blood being overly acidic. The reference values for diagnosing respiratory acidosis are a pH lower than 7.35 and a pCO₂ higher than the normal range of 35-48 mm Hg for males and 32-45 mm Hg for females. In response to respiratory acidosis, the kidneys may compensate by increasing the levels of bicarbonate (HCO₃-) in the blood, which would result in a base excess.
For instance, in the case study of a 64-year-old male with asthma, the laboratory results showing a pH of 7.31 and an increased pCO₂, along with an increased HCO₃-, indicate respiratory acidosis with partial renal compensation. The asthma contributed to these lab results by impairing the ability of the lungs to expel CO₂, leading to its accumulation in the blood and thus causing the acidosis.