Emergency departments (ED) are facing problems related to the growing demand of care. Patients' management is carried out according to the type of patient and care required: already scheduled patients and non-scheduled urgent and non-urgent patients arriving in the ED. One of the main problems confronted in hospitals is the permanent interference between these different types of patients to be treated under the stochastic behaviors of consultation time and arrival flows, which prevents any prior planning. The present work proposes a dynamic scheduling method, considering the impact of new patients' arrivals on the treatment of patients already scheduled to minimize the mean waiting time of patients in the ED. The originality of this work is to assign, at the time of arrival, a scheduled time to each patient in order to reduce their stress. The performance of the proposed method is examined through a concrete application in the Pediatric Emergency Department of CHRU of Lille.