Transbronchial cryobiopsy in different freezing time is performed in patients with undefined diffuse parenchymal lung diseases, and assess the diagnostic yield and safety.

Transbronchial cryobiopsy in different freezing time is performed in patients with undefined diffuse parenchymal lung diseases, and assess the diagnostic yield and safety. This is a prospective randomized control trial.

Inclusion Criteria:

1. The patients are admitted in the institution as DPLD, while undefined after thorough history collection, laboratory examination and radiological data.
2. Transbronchial cryobiopsy(TBCB) is indicated by clinicians for definitive diagnosis and patients are content with the examination with agreement signed.
3. Blood gas analysis, routine blood test, ECG examination, coagulation function, immunological examination, chest HRCT, and liver/kidney function test have been completed.

Exclusion Criteria:

1. The radiological data indicates non-DPLD
2. The clinical examinations mentioned above are not completed.
3. The patient cannot endure or does not agree the procedure.