ecrin-mdr-crcClinical2019colorectal cancerColorectal CancerOtherhttps://newmdr.ecrin.org/Study/2685513China7ECRIN MDRRecruitingfalseIdentification of the Risk Factors of Postoperative Pulmonary Complications in Elderly Patients Undergoing Elective Colorectal SurgeryInterventions: PPC group+ Non-PPC group:N/A Primary outcome(s): ASA;age Study Design: Factorial2019-07-152685513ChiCTR1900024506