Vomiting after stent placement

My dad has stage 4 esophageal cancer. He had a stent placed last Friday at the esophageal/stomach junction, as he was unable to swallow his saliva. Since then, he has kept down maybe 1/4 of the liquids he's consumed. He's tried water, jello, mashed potatoes, and canned fruit. Since the sphincter is held open, everything just slides right back up. His doctor is hoping that this improves over time. Has anyone experienced similar reactions to stents? Any advice?