Obesity and perioperative acute kidney injury: a focused review.

Obesity has reached epidemic proportions in the developed world today. Obesity is a significant risk factor for cardiovascular disease, hypertension, diabetes mellitus, and chronic kidney disease. There has been renewed interest in the role of perioperative renal dysfunction with the establishment of new diagnostic criteria for kidney dysfunction such as the Acute Kidney Injury Network criteria and the Risk-Injury-Failure-Loss End-stage kidney disease criteria. There is increasing evidence pointing to the role of visceral adipose tissue and adipokines in the pathophysiology of obesity. Furthermore, the traditional methods of quantifying obesity such as body mass index are increasing being questioned because they may not accurately reflect true visceral obesity and may skew epidemiologic classification of metabolically healthy patients. Recent epidemiologic studies suggest the existence of an obesity paradox wherein obese patients seem to have superior perioperative outcomes compared with patients with normal and low body mass index. We seek to review the epidemiologic and pathophysiologic aspects of obesity, especially with respect to structural and functional changes in kidney function and their impact on perioperative outcomes.