1. Circulation / Haemodynamics

2. Objectives
At the end of this Lecture You would Know:
1. Different Types of Vessels and their role in Vascular physiology
2. Different aspects of Controlling Mechanisms of circulatory system

3. Circulation/Haemodynamics
Haem------Blood
Dynamics- Motion or Flow

4. Importance
Management of Hemodynamic in every surgery is one of the most important aspect of management
Leading cause of death in most of the major surgeries is hemodynamic failure

5. Major Divisions Systemic Circulation Pulmonary Circulation
Supplies blood to all parts of the body
Also called greater circulation or peripheral circulation
Pulmonary Circulation
Circulation in the lungs
For the oxygenation of the blood (Hb)

8. Circulatory System Heart- Pumps blood Arterioles- Resistance vessels
Aorta – Elastic vessel. Windkessel vessel
Arteries-Conducting vessels.
Carry blood away from heart
Arterioles- Resistance vessels
Metarterioles- Regulatory vessels
Regulates blood flow

9. Circulatory System Capillaries- Exchange vessels
Exchange of nutrients with & metabolites of tissues
Veins and venules – Capacitance vessels
Storage & Carrying blood toward the heart

10.  Capacitance of blood vessels describes the distensibility of blood vessels located within the body. It is inversely proportional to elasticity.

11. Volume of blood in circulation
Systemic circulation 84 %
Veins 64 %
Arteries 13 %
Arterioles & capillaries 7 %
Heart & Lungs 16 %
Heart 7 %
Pulmonary vessels 9 %

12. More than 64 % of the blood is in the systemic veins

13. Flow = Pressure/R Flow = P1-P2 /R P2 P1 FLOW Pressure Distance Force
( Pressure Head )
FLOW
Flow = P1-P2 /R

14. Poiseuille and Resistance
Poiseuille’s Equation
Flow= ∆P.∏r4
8ŋL
Where
∆ P= Driving Pressure
r = radius
ŋ=Viscosity
L= Length of the tube

15. Poiseuille and Resistance
Radius or diameter is KEY Factor.
 radius by 1/2  resistance by 16 FOLD -

16. Laminar / Turbulent Flow
Reynold’s Number
Re=v.d.p ŋ
Where
V=mean vel of blood flow
d= diameter in cm
p= density
ŋ = viscosity of blood
> 2000

17. Blood Pressure Defined as: Pressure exerted by the flowing blood
laterally on the vessel wall per unit area.
Importance;
Maintaining pulsatile blood flow to all tissues of the body

18. Types of Blood Pressure:
A. Systolic
B. Diastolic
C. Pulse Pressure
D. Mean Arterial Pressure
DIASTOLE
120
80 mmHg
120 mmHg 80
SYSTOLE

19. Determinants of B.P B.P= COP x TPR

20. Determinants of Systolic BP 1. Stroke Volume 2. Distensibility
ARTERIES (LOW COMPLIANCE)
Determinants of Systolic BP
1. Stroke Volume
2. Distensibility
Determinants of Diastolic BP
1. Elasticity of Aorta
2.TPR
DIASTOLE
80 mmHg
120 mmHg
SYSTOLE

21. Brachial Artery Pressure curve, showing Systolic / Diastolic & MAP
DIASTOLE
Mean Art Pr = DBP + 1/3rd PP
Pulse Pressure = SBP- DBP
= =40
80 mmHg
120 mmHg
SYSTOLE

22. Flow in Rigid tube
Pump ON
Water
Pump
OFF X
X- No Flow
Water

23. Flow in Aorta Pump Pump Rubber tube
Water
Terminal end Narrowed
Pump
Rubber tube
Water
Continous Flow Both during systole & Diastole

24. Stretching of Elastic Vessel(Aorta) during Systole & Recoil during Diastole

25. Bernoulli’s Principal, Application

26. Total Peripheral Resistance, (TPR)
Flow = P1-P2 R
Total Peripheral Resistance=100-0 =100 mmHg
(TPR) ml /Sec (COP)
TPR (in systemic Circulation) = 1 PRU
TPR (In Pulmunary Circulation) = 16-2 =14/100
= 0.14 PRU

27. Effect of Gravity on Arterial & Venous Pressures