Preoperative assessment for patients with renal impairment

The kidneys play an essential role in homeostasis. They regulate crucial physiological variables including blood pressure, acid-base, fluid and electrolyte balance. With an ageing and increasingly diabetic population, the prevalence of chronic kidney disease is increasing. Acute kidney injury is also very common in hospitalized patients. It is therefore essential to identify patients with renal impairment and assess its impact on a patient's physiology, with aberrancies such as anuria, metabolic acidosis and hyperkalaemia all being potentially life-threatening if untreated. It is these physiological derangements that lead to the observed association of renal impairment with an increased perioperative morbidity and mortality. Prevention, identification and correction of the physiological consequences of renal impairment are vital in improving postoperative outcomes in these patients. This article aims to provide a context and structure for the preoperative assessment of patients with renal impairment irrespective of its cause.