A patient has a systolic/diastolic blood pressure of 130/70 mmHg and a cardiac output of 5 L/min. What is his total peripheral resistance?

Flow=pressure difference/resistance. If central venous pressure is negligibly small compared to mean aerial pressure, we can calculate the peripheral resistance from the data given. The key in obtaining a correct answer is being able to determine mean aerial pressure from systolic pressure Ps and diastolic blood pressure PD. Because of the paicular shape of the pressure curve, this is not simply the arithmetic mean, but rather PD+1/3(Ps-PD), ie, 70+20=90 mm Hg Therefore, resistance+90 mm Hg/5 L/min=18 mm Hg.min/L