Poiseuille equation (airway resistance)


In respiratory physiology, airway resistance is the resistance of the respiratory tract to airflow during inspiration and expiration. In fluid dynamics, the Hagen–Poiseuille equation is a physical law that gives the pressure drop in a fluid flowing through a long cylindrical pipe. While the assumptions of the Hagen–Poiseuille equation are not strictly true of the respiratory tract it serves to show that, because of the fourth power, relatively small changes in the radius of the airways causes large changes in airway resistance. The airway resistance is depended on the length of pipe and the radius of the pipe.

Related formulas


RThe airway resistance (Pa*s/m3)
μThe dynamic viscosity (Pa*s)
lThe length of the pipe (m)
rThe radius of the pipe (m)