What is the ratio of resistance before and after capillaries

The ratio of resistance before and after capillaries is usually 4:1 to 5:1, reflecting the relationship between blood flow resistance at the arterial and venous ends in microcirculation. The pre capillary resistance mainly comes from the contraction state of small and micro arteries, and the smooth muscle tension of these vessels determines the speed at which blood enters the capillary network. Angiotensin and sympathetic nervous system excitation can increase anterior resistance, leading to an increase in the ratio. The posterior resistance of capillaries is influenced by microvessels and venules. When the venous system dilates or blood viscosity increases, the posterior resistance increases and the ratio may decrease. This ratio plays an important role in tissue perfusion and blood pressure regulation. A high ratio may lead to tissue ischemia, while a low ratio may cause congestion.

The measurement of the resistance ratio before and after capillaries requires the use of professional hemodynamic testing equipment, such as laser Doppler flowmeter or microcirculation microscope. The ratio of healthy individuals is relatively stable at rest, but it can fluctuate due to exercise, temperature changes, or disease status. hypertensive patients may experience abnormally increased anterior resistance, while those with venous insufficiency often experience a significant increase in posterior resistance. During clinical evaluation, it is necessary to make a comprehensive judgment based on specific symptoms and blood flow parameters. Maintaining a normal capillary resistance ratio requires regular exercise, control of blood pressure, and blood viscosity. Avoiding prolonged sitting in the same position and quitting smoking and limiting alcohol intake can help promote microcirculation health. If there are symptoms of microcirculation disorders such as limb numbness, pale skin, or bruising, it is recommended to seek medical examination in a timely manner.