Similar problems of dizziness, chest tightness, and long outgassing (big sigh) in older children are associated with autonomic instability, and the underlying causes of autonomic instability may in turn be related to lesions of the respiratory, digestive, and cardiovascular systems. These symptoms occur mostly in quiet situations, such as after a full stomach, while watching TV, writing homework, etc., while the symptoms are less pronounced or absent during exercise. ECG is one of the routine tests, and secondly, 24h ambulatory ECG can be a good remedy for problems missed because of the short duration of the former test, such as atrioventricular block of degree I or II type I that occurs at night. Of course, if the symptoms are related to exercise, an exercise ECG is recommended. In addition, some pediatric symptoms may be associated with high or low blood pressure, etc., and further problems can be detected by 24h ambulatory blood pressure monitoring. If an autonomic imbalance is detected by one of these tests, the physician will recommend an upright tilt test to exclude conditions such as postural tachycardia, taking into account the patient’s clinical condition. If a child’s symptoms occur after recurrent respiratory infections, the physician’s judgment can determine whether pulmonary function tests are needed to clarify the presence of airway obstruction, etc. Of course, each of the above tests is determined by the physician after analyzing the patient’s condition and deciding how to perform the necessary tests to help diagnose the condition according to each patient’s actual situation.