# Systemic Vascular Resistance Calculations

Systemic Vascular Resistance Calculations

#### Calculate Systemic Vascular Resistance – given

• Systolic pressure: 130 mmHg
• Diastolic pressure: 90 mmHg
• Right atrial mean pressure: 4 mmHg
• Cardiac output: 5 L/min

#### Calculate systemic vascular resistance in Wood units

[A] 8 Wood unit
[B] 10 Wood unit
[C] 13 Wood unit
[D] 21 Wood unit

Mean arterial pressure

= (2 diastolic pressure + systolic pressure)/3

= 2X 90 + 130 = 210/3 = 70 mmHg

Systemic vascular resistance

= [MAP-CVP] / C.O

= (70 – 4) / 5

= 13.2 Wood unit

Normal: 900-1200 dynes.sec.cm-5 or 11-15 Woods Units.

Hybrid resistance units (HRU) – also known as Wood units in honor of Paul Wood.

1 HRU = 1 Woods unit = 80 dyne.sec/cm5 = Pa·s/m3

Pa = pascal = pascal (symbol: Pa) is the unit of pressure in the International System of Units , 1 pascal = N/m2

• Wood units is used to measure – Peripheral vascular resistance

#### Units for measuring vascular resistance

1. dyn·s·cm−5
2. pascal seconds per cubic metre (Pa·s/m3)
3. mmHg·min/L. – called as hybrid resistance units (HRU) , also known as Wood units