ABSTRACT
BASIC PHYSIOLOGY The kidneys help preserve intravascular volume, excrete products of metabolism, and regulate acid-base status. The physiology of sodium and water reabsorption that is linked to renal blood fl ow engages surgical critical care clinicians on a daily basis. Urine output is commonly used as a substitute for measurement of renal perfusion and as a surrogate for cardiac output monitoring. Acid-base disturbances are also a daily feature of surgical critical illness. Acute kidney injury (AKI) regularly accompanies shock from hypoperfusion and/or systemic infl ammation. Avoidance of and/or limiting the duration of AKI is linked to the avoidance and/or limitation of shock and, therefore, is an important strategy to improve outcome in surgical critical illness.
