Sivelestat Treatment for Postoperative Organ Protection in Type A Aortic Dissection

The goal of this multicenter, double-blind, randomized controlled trial is to learn if sivelestat sodium (Siv) can protect the organ function in patients suffered operation for acute type A aortic dissection. The main questions it aims to answer are: * Can the 3-day-treatment of Siv enlarge the Day-0-to-Day-5 drop in the organ-health score (SOFA score)? * Can this treatment significantly shrink the area under the SOFA curve from first dose to Day 5? * Can this treatment significantly improve the end of patients in 28 days (clinical outcomes)? Researchers will compare drug Siv to a placebo (a look-alike substance that contains no drug) to see if drug Siv works. Participants will: * Take drug Siv or the placebo through vein continuously for 72 hours * Receiving regular intensive care in ICU after the operation