Here are some situations where someone might say the demand changed. As the AIDS epidemic spread, sales of rubber gloves skyrocketed. A wellness clinic hires a handsome receptionist. More patients come. You cut your price on physical examinations.
More patients come.
The Federal government releases a report saying that your hospital has death rates that are significantly higher than average. Patients go elsewhere. You extend your operating hours. You see more patients per day. You double what you charge patients in your hospital emergency room.