Ⅱ型呼吸衰竭的实验室指标是

A．PaO<SUB>2</SUB>＜50mmHg，PaCO<SUB>2</SUB>＞60mmHg
B．PaO<SUB>2</SUB>＞60mmHg，PaCO<SUB>2</SUB>＜50mmHg
C．PaO<SUB>2</SUB>＜60mmHg，PaCO<SUB>2</SUB>＞50mmHg
D．PaO<SUB>2</SUB>＜55mmHg，PaCO<SUB>2</SUB>＞50mmHg