What is the most appropriate first step for a school nurse when a 10-year-old with chest pain is evaluated?

In evaluating a 10-year-old with chest pain, obtaining a peak flow reading is the most appropriate first step. This action is crucial in determining whether the chest pain is related to a respiratory issue, such as asthma or another form of airway obstruction. A peak flow meter measures how well air moves out of the lungs, providing valuable information about the child's pulmonary function.

Identifying potential respiratory causes for chest pain is essential in this scenario because it allows the nurse to assess the necessity for immediate intervention, such as bronchodilator therapy if the readings indicate compromised airflow. Once respiratory status is obtained and assessed, further steps can be taken based on the results.

In contrast, other options do not address the immediate need to evaluate the cause of the chest pain. Calling the parent may be necessary later, but it does not directly assist in assessing the child's condition. Having the adolescent lie down might provide some comfort, but it does not investigate the underlying issue. Administering a bronchodilator without prior assessment of respiratory function could lead to inappropriate treatment if the chest pain is not due to asthma or related conditions.