In her house in Ypsilanti, Mich., Barbara Meade said, “there are walkers and wheelchairs and oxygen and cannulas all over the place.” Ms. Meade, 82, has chronic obstructive pulmonary disease, so a portable oxygen tank accompanies her everywhere. Spinal stenosis limits her mobility, necessitating the walkers and wheelchairs and considerable help from her husband, Dennis Meade, who serves as her primary caregiver.