Final answer:
Acute respiratory failure is characterized by low PaO2 and SaO2, with high or variable PaCO2 depending on the type of failure. It indicates a severe impairment of gas exchange in the lungs, often requiring immediate medical intervention.
Step-by-step explanation:
Acute respiratory failure is a condition in which the respiratory system fails in one or both of its gas exchange functions: oxygenation and carbon dioxide elimination. In acute respiratory failure, you will typically see abnormalities in the arterial blood gas (ABG) values. The partial pressure of oxygen in the blood (PaO2) is often low, saturation of oxygen (SaO2) is below normal levels, and partial pressure of carbon dioxide (PaCO2) may be high or low depending on whether the respiratory failure is of the hypercapnic or hypoxemic type.
In hypercapnic respiratory failure (also known as ventilatory failure), the PaCO2 is above the normal range (greater than 45 mmHg) due to inadequate respiratory ventilation. For hypoxemic respiratory failure, PaO2 is below the normal range (less than 80 mmHg), and SaO2 is typically below 95%, indicating an impaired transfer of oxygen into the blood.
Compensation can occur in chronic cases where the body attempts to restore acid-base balance. With respiratory acidosis, which would be indicated by a high PaCO2, the kidneys may increase bicarbonate production, generally seen over a period of days, to buffer the increased acidity. Conversely, in respiratory alkalosis, marked by low PaCO2, the kidneys may excrete more bicarbonate to decrease blood pH.
Typical ABG values associated with acute respiratory failure are as follows: PaO2 < 60 mm Hg, SaO2 < 90%, PaCO2 > 50 mm Hg with pH < 7.35 for hypercapnic respiratory failure, and PaCO2 could be normal or low for hypoxemic respiratory failure.