Hypoxia-induced Decrease in Renal Medullary Osmolality: Prevention with dDAVP

Acute kidney injury (AKI) may result from perioperative renal medullary hypoxia. Despite high oxygen delivery to the kidney, the medullary thick ascending limb (mTAL) in the outer renal medulla is susceptible to hypoxia because of its high oxygen consumption and relatively low rate of blood flow. The objective of this study was to evaluate the effect of a low pO2 (8% FiO2 for 5 h) on the major function of the mTAL and to develop a strategy to protect the mTAL in this setting. Evidence of hypoxia-induced reduction in mTAL function included low interstitial and urine osmolality but only a minimal rise in Na+ excretion; this was prevented by pre-treatment with desmopressin acetate (dDAVP), a vasopressin analogue which may increase tissue pO2. A decrease in urine osmolality may be of diagnostic value for hypoxic renal damage and dDAVP may prevent acute kidney injury in the perioperative setting.MAS