Calculating the urine output
The question asks for average urine output in mL/kg/h. Two steps are needed: first convert the total volume into an hourly rate, then divide by body weight. Hourly output is 128 mL ÷ 4 h = 32 mL/h; per kilogram, 32 mL/h ÷ 72 kg = 0.444, which rounds to 0.44 mL/kg/h. This is below the usual target of at least 0.5 mL/kg/h, so the nurse reports it for reassessment of fluid therapy.
Why urine output matters in pancreatitis
Acute pancreatitis causes large fluid shifts into the retroperitoneum and bowel, together with vomiting and poor intake. Early, adequate IV fluid, often lactated Ringer's solution, is a cornerstone of treatment. Urine output is one of the simplest bedside measures of whether fluid resuscitation is adequate. A falling output may signal hypovolemia and reduced kidney perfusion, which can progress to acute kidney injury and organ failure.
| Option | How it was obtained | Error |
|---|
| 1.78 mL/kg/h | 128 ÷ 72 | Did not divide by hours |
| 0.59 mL/kg/h | 128 ÷ 3 ÷ 72 | Divided by 3 hours instead of 4 |
| 0.44 mL/kg/h | 128 ÷ 4 ÷ 72 | Correct |
| 2.25 mL/kg/h | 72 ÷ 32 | Inverted the ratio |
Avoiding common calculation errors
Each distractor reflects a typical mistake. Dividing the 4-hour total directly by weight forgets the time unit. Dividing by 3 instead of 4 happens when hourly readings are counted as intervals. Dividing weight by hourly output inverts the ratio and yields a number that should look implausibly high. A quick check is to remember that a normal adult output is roughly in the range of half to one milliliter per kilogram per hour, so results far above this should prompt a recheck of the setup.
Nursing actions
The nurse reports the low output, assesses for other signs of hypovolemia such as tachycardia, hypotension, and dry mucous membranes, checks that the catheter or collection system is not obstructed if one is present, and anticipates a review of the fluid rate and kidney function tests.
Exam takeaway
Key point For mL/kg/h, divide volume by hours first, then by kilograms. An adult output below 0.5 mL/kg/h is reported.