Kidney Injury, Acute

This pilot study is designed to test the logistics and recruitment of a trial testing the benefit of sodium nitrate in the prevention of contrast-associated kidney injury in a group of patients at high-risk.

Primary objectives of this study is to develop and validate a predictive model for acute kidney injury after non-cardiac surgery based on machine learning. Secondary objectives of this study is to incorporate frailty assessment as a new predictor into the model and measure its incremental value was measured.

The goal of this clinical performance study is to evaluate the accuracy and usability of the Eaglenos Creatinine Test System（referred to as EG）, a point-of-care testing (POCT) system that consists of a handheld device and its associated creatinine test strips, intended for home use by laypersons with non-dialysis-dependent kidney disease. The main questions it aims to answer are: 1. How consistent are creatinine measurements from the investigational creatinine test system compared with the clinical standard method? 2. How usable is the Creatinine Monitoring System for laypersons in a home setting? Researchers will compare creatinine results obtained with the investigational creatinine test system (fingerstick capillary whole blood) to those from a Cobas biochemical analysis system（referred to as Cobas) (venous plasma) to determine whether the investigational device provides accurate and reliable measurements. Participants will: 1. Provide a venous blood sample for comparative testing. 2. Perform self-testing using the Creatinine Monitoring System without prior training. 3. Complete a usability questionnaire about their experience with the investigational creatinine test system.