Definition of rf Disorders of external respiratory function Pao2<60 mmHg(8.kpa) while breathing air at rest, with or without Paco2 >50 mmHg 6. 67 kpa). judgment standard: PaO2 <60 mmHg, Paco2 >50 mmHg hypotonic hypoxia with(or without) respiratory acidosis6 Definition of RF Disorders of external respiratory function PaO2 <60 mmHg (8.0kpa) while breathing air at rest, with or without PaCO2 >50 mmHg(6.67kpa). judgment standard: PaO2 <60 mmHg , PaCO2 >50 mmHg hypotonic hypoxia with (or without) respiratory acidosis