This study will be conducted in the Affiliated Hospital of Nantong University. Sixty CRC patients are randomized into traditional ventilation strategy group (control group) and lung protective ventilation strategy group (experimental group), there were 30 cases in each group. The control group adopted conventional ventilation strategies: tidal volume (VT)=10-12 ml/kg, respiratory rate ( f)=12 breaths / minute, positive end expiratory pressure（PEEP）=0 cmH₂O, fraction of inspired oxygen =0.5; the experimental group used lung protective ventilation strategies: tidal volume ( VT)=6-8 ml/kg, f=12 breaths / minute, positive end expiratory pressure (PEEP)=6-8 cmH₂O, fraction of inspired oxygen =0.5, mechanical ventilation every 30 minutes (continuous positive airway pressure 30 cmH₂O about 30 seconds). 4 ml of central venous blood was extracted at 3 time points within 24h, and relevant experimental indexes were determined. Observe the effect of lung protective ventilation strategy on the microenvironment of tumor inflammation and related hematological indexes NLDA, PDM, SII and PNI in patients undergoing colorectal cancer surgery. Follow-up frailty score and quality of recovery score at 1,3,6, and 12 months after surgery (QoR-15 score scale).
