呼吸衰竭是指()
A. PaO<sub>2</sub><50mmHg和PaCO<sub>2</sub>>50mmHg
B. PaO<sub>2</sub><50mmHg,或伴有PaCO<sub>2</sub>>50mmHg
C. PaO<sub>2</sub><60mmHg和PaCO<sub>2</sub>>50mmHg
D. PaO<sub>2</sub><60mmHg和PaCO<sub>2</sub>>60mmHg
E. PaO<sub>2</sub><60mmHg,或伴有PaCO<sub>2</sub>>60mmHg