Comparison of the effects of different mechanical ventilation modes on the incidence of ventilation-associated pneumonia: a case study of patients undergoing thoracic surgery

Objective: To investigate the effects of different mechanical ventilation modes on the incidence of ventilator-associated pneumonia (VAP) in patients undergoing thoracic surgery. Methods: From June 2019 to December 2021, the clinical data of 96 patients undergoing thoracic surgery in Cangzhou Central Hospital were retrospectively analyzed. A total of 44 patients who underwent constant flow mode were included in the control group (CG), and 52 patients who underwent auto flow mode were included in the observation group (OG). The respiratory mechanics, hemodynamics, blood gas analysis and serum levels of lung injury markers at different time points were compared between the two groups, and the incidence of VAP was analyzed. Results: At 1 hour and 4 hours of ventilation, the peak airway pressure (Ppeak), Pmean mean airway pressure (Pmean) and airway resistance (Raw) of the OG were lower than those of the CG, and the dynamic lung compliance (Cdyn) was higher than that of the CG (P<0.05). There were no statistically significant differences in mean arterial pressure (MAP), heart rate (HR), blood oxygen saturation (SpO(2)), PH, arterial partial pressure of oxygen (PaO2), arterial partial pressure of carbon dioxide (PaCO2) between the OG and CG at 1 hour and 4 hours of ventilation respectively (P>0.05). The serum levels of pulmonary surfactant associated protein A (SP- A), human Clara cell protein (CC16) and serum ferritin (SF) in the OG were lower than those in the CG (P<0.05). The incidence of VAP in the OG (3.85%) was lower than that in the CG (15.91%) (P<0.05). Conclusion: In mechanical ventilation, auto flow mode can reduce the incidence of VAP, improve respiratory mechanics, and reduce lung injury in patients undergoing thoracic surgery, but has no significant effect on hemodynamics and blood gas analysis.