A 74-year-old man is brought to the hospital by his nephew after complaining of severe abdominal cramping and swelling. He claims to have had a stomach virus for the past few days. His symptoms include nausea, anorexia, mild discomfort, and constipation. Within the last 12 hours, his pain has increased in intensity, and he has vomited small amounts of greenish liquid several times. The physician diagnoses his condition as a possible bowel obstruction. An appropriate nursing diagnosis for this patient would be: