The purpose of this study is to demonstrate the effectiveness of ischemic preconditioning in the emergency department to prevent contrast induced nephropathy

The research will be conducted of emergency medicine department in The Derince Training and Research Hospital. Patients ages 18 and older, who will be received contrast enhanced CT scan in the emergency medicine department will be included to the study. Patients will be excluded from the study if The Mehran Risk Score is under 6 points. The Mehran Risk Score is a scoring system for prediction of contrast-induced nephropathy. This CIN (Contrast induced nephropathy) risk stratification score based on 8 variables. The variables included in the CIN risk score are: 1) patient-related characteristics (i.e., age >75 years, diabetes mellitus, chronic congestive heart failure, or admission with acute pulmonary edema, hypotension, anemia, and chronic kidney disease); and 2) procedure related characteristics (i.e., the use of elective IABP (Intra aortic balloon pump) or increasing volumes of contrast media). It is categorized into 4 groups according to MRS (Mehran Risk Score) (low-risk: 5 (7.5%); medium-risk: 6-10 (14%); high-risk: 11-16 (26.1%); and very high-risk: 16 (57.3%).Normal salin at a rate of 3 mL/kg/hour per 1 hour before contrast agents exposure followed by 1 mL/kg/hour for 6 hours after the procedure is administered whose Mehran risk score is greater than 6 in our daily practice. Patients with risk factors for CIN are recommended about the necessity of follow-up care with their physicians within 48-72 hours. Patients with low risk of contrast induced nephropathy, previous allergic reactions to contrast material, hemodynamically unstable and require excessive fluid resuscitation, undergoing surgical procedures, require renal-replacement therapy, who refuse to participate the study will be excluded. All of the emergency medicine physicians will be informed of the study. Participants were randomly assigned into two groups with a 1:1 allocation following simple randomization procedures by a program (www.randomization.com) generating an online random number. All participating patients will receive the standard hydration schedule as mentioned before. Patients in the study group will receive ischemia and reperfusion of the arm by inflating a blood pressure cuff around the arm at 50 mmHg above the systolic blood pressure for 5 minutes, followed by 5 minutes of reperfusion and this cycle will be repeated three times. Patients in sham group, will receive ischemia and reperfusion of the arm by inflating a blood pressure cuff around the arm at 10 mmHg below the diastolic blood pressure for 5 minutes, followed by 5 minutes of reperfusion and this cycle will be repeated three times. The allocation sequence will be concealed from the researchers and participants in sealed, sequentially numbered envelopes. Envelopes will be opened by the nurse who will administer the protocol. Less than 100 mL of nonionic, hypoosmolar contrast agent will be injected in all CT scans.All of the participants will be recommended about the necessity of follow-up care with their physicians within 48-72 hours. Participants will be called 72 hours after the treatment. Patients who are diagnosed with CIN will be followed for one month to see whether they will develop renal failure requiring renal replacement therapy. After 72 hours the laboratory results will be recorded by the researchers.

Inclusion Criteria:

• Participants, older than 18 years old and received contrast enhanced CT scan in the emergency medicine department
• The Mehran Risk Score is greater than 5 points

Exclusion Criteria:

• The Mehran Risk Score is under 6 points
• Participants who doesn't want to enroll the study