Pulse pressure difference of 18mmHg is not normal. Differential pulse pressure is the difference between systolic pressure and diastolic pressure, and the normal differential pulse pressure is 30-40mmHg. If the differential pressure is <20mmHg, it is called too small a differential pressure; when the differential pressure is >60mmHg, it is called too large a differential pulse pressure. Excessively low pulse pressure is usually due to increased peripheral vascular resistance, increased heart rate, and large amounts of pericardial effusion. All of these factors cause an increase in diastolic blood pressure, resulting in a low blood pressure differential. A blood pressure differential of 18 mmHg is less than 20 mmHg, so it is abnormal. It is recommended to go to the hospital in time when the pulse pressure difference is too small, to be examined under the guidance of the doctor, and to receive symptomatic treatment after clarifying the cause of the disease.