Question

(5) (a) Calculate the total peripheral vascular resistance in the systemic and pulmonary systems for someone with a steady-state blood flow rate of 5 L/min, and with 120 mmHg/80mmHg blood pressure in the systemic system and 25 mmHg/8mmHg pressure in the pulmonary system. Express your answer in the units of PRUS (dyne-s/cm), which are CGS units and those that are often used by cardiologists. (b) The expression given in the text for this vascular flow resistance should be corrected because it uses the average pressure at the beginning of the system instead of the pressure drop across the system. For the systemic system the final pressure is that at the right atrium (2 mmHg) and for the pulmonary system it is that at the left atrium (5 mmHg). How does using the actual pressure drop affect your calculations in part (a) (both qualitatively and quantitatively)?

Answer 1

MAP NI diastolicpressure + systolicpressure

Systemic Vascular resistance, SVR is given by CO=cardiac output

MAP= mean arterial pressure; CVP= cental venous pressure;  

SVR= MAP - CVP CO x 80

Pulmonary vascular resistance, PVR is given by

SVR= MAP - CVP COX80 = 93.3mmHg - 2mm Hg x 80 = 1460dyne- 5L/min S/cm5

MPAP - PAOP PVR= X80 = 13.6 – 51 x80 = 137.6dyne-s/cm CO

where , PAOP= pulmonary artery occlusion pressure also known as final left atrium oressure, CO= cardiac output

MPAP = NI diastolicpressure + systolicpressure

Total peripheral vascular resistance=

1460 + 137.6 = 1597.6dyne - s/cm