**1. Introduction**

#### **1.1 Acute kidney injury**

Acute kidney injury (AKI) is a widespread problem. It is often used interchangeably with acute renal failure. The incidence of AKI in intensive care unit (ICU) is wide ranging from 5% to 50% and specific to the type of ICU. AKI can have quite a profound impact on the patient and is associated with severe morbidity and mortality. Mortality can range from 40% to >60%. There are consensus definitions of AKI, and they are broken down into three types.
