Final answer:
The patient's confusion could be caused by medications with anticholinergic properties or by opioids, which are known to cause confusion in the elderly or after surgery.
Step-by-step explanation:
The confusion the elderly patient is experiencing post-gastric surgery could be due to a number of factors including age, the stress of surgery, or indeed, a medication side-effect. Especially in older adults, certain medications can contribute to delirium or confusion.
A common category of medications known for causing such side effects in the elderly are anticholinergics, which can be found in various drug classes including antihistamines, antipsychotics, and medications for overactive bladder.
It is also possible that postoperative pain medications such as opioids can cause confusion in susceptible individuals.
The nurse reviewing this patient's medication record should look for recent changes to the medication regimen, particularly any new medications that may have anticholinergic properties or are known to cross the blood-brain barrier, affecting mental status.