Characteristic of type-II respiratory failure is: September 2010

Ans. D: Low PaO2 and high PaCO2 Type II Respiratory Failure (Ventilatory Failure: Aerial Hypercapnia): Paial pressure of CO2 in the aerial blood reflects the efficiency of ventilatory mechanism that clears (washes out) CO2 produced during tissue metabolism. Type II failure can be caused by any disorder that decreases central respiratory drive, interferes with the transmission of signals from the central nervous system, or impedes the ability of respiratory muscles to expand the lungs and chest wall. Type II failure is characterized by an abnormal increase in the paial pressure of CO2 in the aerial blood (PaCO2 > 46 mm Hg), and is accompanied by simultaneous fall in PAO2 and Pa02, therefore PAO2 - Pa02 difference remains unchanged.