Replace measured losses plus insensible loss
This client is now oliguric from acute kidney injury (AKI) and has signs of fluid overload. Because his kidneys cannot excrete water normally, his fluid intake is restricted to replace only what he loses. The order is to give all measured losses of the previous 24 hours plus 500 mL for insensible loss. His measured losses were 320 mL of urine and 180 mL of nasogastric drainage. 320 + 180 + 500 = 1,000 mL is his total fluid allowance for the next 24 hours.
| Option | How it was obtained | Error |
|---|
| 680 mL | 180 + 500 | Leaves out the urine output |
| 820 mL | 320 + 500 | Leaves out the nasogastric drainage |
| 1,000 mL | 320 + 180 + 500 | Correct |
| 1,500 mL | 320 + 180 + 1,000 | Doubles the insensible allowance |
Why this formula is used
In the oliguric phase of AKI, giving more fluid than the body loses leads to fluid overload, with edema, hypertension, pulmonary congestion, and dilutional hyponatremia. Replacing exactly what is lost keeps the fluid balance even. Insensible loss through the skin and lungs cannot be measured directly, so a fixed allowance is added. All measured outputs count, including urine, vomitus, nasogastric drainage, wound drainage, and diarrhea, which is why leaving out the NG drainage is an error.
Nursing care around the restriction
The nurse spreads the allowance across the day, includes all oral and IV fluids, and counts fluids given with medicines. Accurate intake and output records and daily weights are essential, and a weight gain suggests fluid retention. Thirst can be eased with ice chips counted as fluid, mouth care, and sour candies if allowed. The nurse also monitors for hyperkalemia, metabolic acidosis, and signs of worsening overload such as crackles and breathlessness.
Watch out! This client's AKI followed upper gastrointestinal bleeding with hypotension, a prerenal insult that progressed. Bleeding risk remains high because he takes aspirin and clopidogrel, so monitor for further bleeding while managing fluid restriction.
Exam takeaway
Key point! In oliguric AKI, fluid allowance equals all measured losses of the previous 24 hours plus the ordered insensible allowance, often 500 mL. Count every measured output, and keep records and daily weights accurate.