呼吸衰竭的动脉血气诊断指标是

A．PaO<SUB>2</SUB>＜50mmHg，PaCO<SUB>2</SUB>＞60mmHg
B．PaO<SUB>2</SUB>＜50mmHg，PaCO<SUB>2</SUB>＞70mmHg
C．PaO<SUB>2</SUB>＜55mmHg，PaCO<SUB>2</SUB>＞55mmHg
D．PaO<SUB>2</SUB>＜60mmHg，PaCO<SUB>2</SUB>＞50mmHg
E．PaO<SUB>2</SUB>＜70mmHg，PaCO<SUB>2</SUB>＞40mmHg