Abstract: Objective: To observe the influence of methylprednisolone in the respiratory mechanical parameters in the elderly patients undergoing major surgeries with general anesthesia intubation after mechanical ventilation,and to investigate whether methylprednisolone can improve the respiratory system degenerative diseases and benefit the mechanical ventilation. Methods: Sixty patients undergoing elective line laparotomy were divided into experimental group and conrol group (n=30) according to their wishes. The patients in experimental group receieved intravenous injection of methylprednisolone 1 mL (40 mg) after endotracheal intubation,and the patients in control group receieved 1 mL intravenous saline water injection.The airway peak pressure (Ppeak), airway platform (Pplat), lung compliance (Compl), and airway resistance (Raw) of the patients in two groups were recorded at the time of immediately before administration and 10,20,30,40 min after administration. The arterial blood oxygen partial pressure(PaO₂),arterial blood CO₂ partial pressure(PaCO₂),CO₂ partial pressure at the end of breathe out(PetCO₂) of the patients were detected at the time of immediately before administration and 20 min after administration. Results: Compared with before administration, the respiratory mechanics parameters of the patients in control group 10,20,30,40 min after administration had no statistically significant differences (P>0.05); the Comple of the patients in experimental group was singnificantly increased (P<0.05), and the Ppeak, Pplat,and Raw were significantly decreased (P<0.05).Compared with control group, the Compl of the patients in experiment group 10,20,30,and 40 min after administration were significantly increased (P<0.05),and the Ppeak, Pplat, and Raw were decreased (P<0.05). Compared with before administration,the PaO₂,PaCO₂,and PetCO₂ of the patients in control group 20 min after administration had no significant differences(P>0.05);the PaCO₂ and PetCO₂ of the patients in experimental group 20 min after administration were decreased(P<0.05),and the PaO₂ was increased(P<0.05).Compared with control group,the PaCO₂ and PetCO₂ of the patients in experimental group 20 min after administration were decreased(P<0.05),and the PaO₂ was increased(P<0.05). Conclusion: Methylprednisolone can obviously reduce PaCO₂,Peak, and Pplat and increase PaO₂ and Compl; methylprednisolone has possibility in improving the adverse effects of degenerative disease of respiratory system on general anesthesia in the elderly patients.

Key words: methylprednisolone, respiratory mechanics, general anesthesia, elderly