The fluid to hang
When a bag of central parenteral nutrition (PN) runs out and the next bag is delayed, the nurse hangs dextrose 10% in water at the same rate, 80 mL/h, as ordered, until the new bag arrives. This maintains the glucose supply and prevents rebound hypoglycemia.
Why sudden interruption is dangerous
PN contains a high concentration of dextrose. In response, the pancreas secretes a large, steady amount of insulin. If the infusion stops suddenly, the insulin level stays high for a while after the glucose supply disappears, and blood glucose can fall sharply. This rebound hypoglycemia may cause sweating, shakiness, tachycardia, confusion, and in severe cases seizures. Hanging dextrose 10% at the same rate provides a similar glucose load so the insulin response has something to act on until PN resumes. The glucose level is checked as ordered during this time.
| Option | Glucose delivered | Assessment |
|---|
| Dextrose 10% at 80 mL/h | Closest to the PN glucose load | Correct |
| Dextrose 5% at 80 mL/h | Half the glucose | May not prevent rebound hypoglycemia |
| Dextrose 10% at 40 mL/h | Half the glucose | May allow rebound hypoglycemia |
| 0.9% sodium chloride at 80 mL/h | No glucose | Does not prevent rebound hypoglycemia |
Why the other choices fail
Watch out! Dextrose 5% at the same rate and dextrose 10% at half the rate both look like reasonable compromises, but each delivers only half the glucose of the correct option, which may not cover the high circulating insulin. Normal saline keeps the line open but provides no glucose at all. The nurse also never tries to "catch up" a delayed PN infusion by increasing the rate later, because a sudden glucose load can cause hyperglycemia and fluid overload.
Related PN safety points
PN is stopped gradually when discontinued, typically by tapering the rate as ordered, for the same reason. The central line used for PN is dedicated to it whenever possible, and the tubing and bag are handled with strict aseptic technique because the high-dextrose solution supports bacterial growth. The nurse monitors capillary glucose regularly, as well as weight, intake and output, and electrolytes according to the PN protocol.
Exam takeaway
Key point! If PN is interrupted, hang dextrose 10% at the same rate as ordered to prevent rebound hypoglycemia. Never stop PN abruptly, and never increase the rate to catch up.