A 26-year-old man met with an industrial accident. He fell from a height and had a fractured left femur. His left thigh got swollen with collected blood. He was rushed to the emergency room. His heart rate was 124 per minute and blood pressure was 76/45 mmHg. His peripheries were cold and clammy. A large bore peripheral venous access was obtained and crystalloids were rushed in. He recovered well over the next couple of hours and his blood pressure returned to 100/60mmHg and heart rate came down to 90 per minute. His left femur was immobilized. He is posted for an open reduction and internal fixation. A blood test done at that time revealed blood urea nitrogen of 48 mg/dL and serum creatinine of 1.6 mg/dL.

Which of the following statements is true?

1. ^{He has suffered from ischemic acute tubular necrosis}
2. ^{He has suffered a traumatic glomerular injury}
3. ^{He has developed a multi system organ dysfunction due to the hypovolemic shock}
4. ^{His kidneys have been injured during the fall}

Answer: The answer is (a). Ischemic acute tubular necrosis is a common cause of acute renal failure in the hospital setting. Volume depletion due to the trauma is the reason for his acute ischemia to the kidneys. Traumatic glomerular injury is a not a known entity. Hypovolemic shock can induce multi system organ dysfunction but it is not likely in this case as the patient is otherwise improving and stable.

1. ^{Generous volume replacement till he is euvolemic}
2. ^{Close monitoring of his serum electrolytes and appropriately correcting them}
3. ^{Maintaining a low blood pressure of sub 90 systolic pressures to minimize renal insult}
4. ^{Initializing dialysis support in case of severe electrolyte disturbances.}

Answer: The answer is (c). The treatment of ischemic acute tubular necrosis includes supportive management. Volume repletion is the corner stone of the treatment. Close observation of the electrolytes is important, as there can be a phase of drastic diuresis in the recovery phase during which can lead to hypokalemia, which can be fatal. The blood pressure should be maintained at an adequate level so as to maintain perfusion of the kidneys. Sub 90 pressures are not advisable. Dialysis support may be required for severe cases.

What is the long-term management of this patient?

1. ^{Complete recovery is the rule and so there is not need for long term follow up}
2. ^{Patients require periodic follow up as a small percent progress to chronic renal failure}
3. ^{Dialysis is the long term treatment of choice for all patients}
4. ^{All patients require renal replacement therapy eventually}

Answer: The answer is (b). Patients with ischemic acute tubular necrosis recover completely. A small subset of patients progress to chronic renal failure. Therefore it is essential to monitor these patients for some period of time.