My mother (86)has a hiatal hernia. the top of her bed is elevated one and a half feet to prevent reflux. however, she slips on the slope. any answer?

Wedge on bed: A commercial foam wedge which would only elevate her from the waist up might be better tolerated. Also, use microfiber or flannel sheets and pajamas (less slippery). A second "body pillow" (extra long pillow), can also be curved around her backside to help prevent sliding, but might make it difficult for her to roll to the other side at night. Also use other methods to improve reflux- checklist