Blood Flow Blood flow = Cardiac output (CO)= HR x SV HR = Heart Rate = Beats/min SV = Stroke volume = ml/min = cm3/min So, blood flow units = cm3/min

Blood Flow = Cardiac Output = π= 3.14 η= viscosity = poise ΔP= pressure gradient = dyne/cm2 r4= blood vessel average radius = cm4 l= length = cm F= Blood Flow = cm3/sec (NOT cm3/min). Important notes: To covert blood pressure gradient from mmHg to dyne/cm2 multiply by 1330. viscosity of plasma = 0.015 poise. Ht=0.45 Males, 0.40 Females.

Blood Velocity V= Velocity of blood = cm/sec F= Blood Flow = cm3/sec A= Area of blood vessel = cm2

Problem A male patient has a systolic blood pressure = 160 mmHg and a diastolic blood pressure = 100 mmHg. Calculate the patient’s cardiac output if patient’s body weight = 100 kg, total blood length = 12 m, average blood vessels radius = 0.5 cm . The patient has normal hematocrit value.

Answer 1) Pressure gradient = MAP = diastolic BP + 1/3(systolic BP – diastolic BP) = 100 + 1/3*60= 120 mmHg = 120*1330 = 159600 Dyne/cm2 l= 12 m = 1200 cm r4= (0.5)4=0.0625 cm4 η= 0.015 (1+2.5*0.45)= 0.0318 poise CO= CO= 102 cm3/sec = 6118 cm3/min = 6.118 Liters/min approx.

Problem 2 In the same patient, calculate the heart rate if the Stroke volume = 70 cm3/beat.

Answer 2) HR= 6118/70 = 87 beats/min. .

Problem A male patient has a systolic blood pressure = 160 mmHg and a diastolic blood pressure = 100 mmHg. Calculate the patient’s cardiac output if patient’s body weight = 100 kg, total blood length = 12 m, average blood vessels radius = 0.5 cm . The patient has normal hematocrit value. In the same patient, calculate the heart rate if the Stroke volume = 70 cm3/beat. If the average blood vessels cross sectional area = 0.3 cm2 , what is the average blood velocity in this patient.

Answer 3) Blood velocity = = 6118/0.3= 20393 cm/min.

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