dr niles kate cardiac output

1. DR NILESH KATE
MBBS,MD
ASSOCIATE PROF
DEPT. OF PHYSIOLOGY
CARDIAC
OUTPUT - I

2. OBJECTIVES
 Definition.
 Measurement of cardiac
output.
 Variations in cardiac output.
 Regulation of cardiac output.
 Heart lung preparation.
 Cardiac & vascular function
curves.
Thursday, February 4, 2016

3. Some Facts………
 Is about 4.8 inches tall and 3.35 inches wide
 Weighs about .68 lb. in men and .56 lb. in women
 Beats about 100,000 times per day
 Beats 2.5 billion time in an average 70 yr. lifetime
 Pumps about 2000 gallons of blood each day
 Circulates blood completely 1000 times each day
 Pumps blood through 62,000 miles of vessels
 Suffers 7.2 mil. CAD deaths worldwide each year
Thursday, February 4, 2016

4. DEFINITION.
 Amount of blood
ejected by each
ventricle per minute.
 CO = SV * HR…..
 SV – Stroke Volume.
 HR – Heart rate.
 Cardiac output
 80 * 70 = 5.6 L/min.
Thursday, February 4, 2016

5. SIGNIFICANCE
 It’s the cardiac output
that decides the rate of
blood flow to the
different parts of the
body.
 Decrease in cardiac
output
 Decrease in blood flow
Thursday, February 4, 2016

6. RELATIONSHIP OF CARDIAC
OUTPUT & VENOUS RETURN
 VENOUS RETURN
 It is the quantity of
blood returned from all
over the body through
the veins into the right
atrium each minute
 Venous return = cardiac
output
Thursday, February 4, 2016

7. Components…….
 Stroke volume
 Amount of blood
pumped by each
ventricle per beat or per
contraction.
 80 ml.
 Stroke volume
depends on –
 End diastolic volume
 contractility
Thursday, February 4, 2016

8. Components…….
 Heart rate
 Under normal
circumstances 70
times/min.
 Increase in heart rate
increases Cardiac
output… but upto limit
 After it decreases due
to decrease in Cardiac
filling.
Thursday, February 4, 2016

9. MINUTE VOLUME
It is the amount of
blood pumped out
by each ventricle per
minute.
MINUTE VOLUME =
Stroke volume x HR
Normal value:
5litres/ventricle/minut
e.
Thursday, February 4, 2016

10. CARDIAC INDEX.
 Cardiac output
is the amount of blood
pumped out per ventricle
per minute per square
meter of body surface area.
 Expressed in relation to the
body surface area.
 Normal value –
3.2L/min/m2
Thursday, February 4, 2016

11. CARDIAC RESERVE.
 Maximum increase in
the cardiac output
above the normal value.
 Expressed in
Percentage.
 Normal values.
 Adults – 300-400%
 Old age – 200-250%
 Athletes – 500-600%
 Variations
 Maximum – Heavy
exercise.
 Minimum – Cardiac
diseases.
Thursday, February 4, 2016

12. MEASUREMENT OF CARDIAC
OUTPUT.
 Methods based on Fick’s
principle
 Indicator or dye dilution
method.
 Thermodilution
 Inhalation of inert gases.
 Physical methods
 Doppler echocardiography.
 Ballistocardiography.
 Cineradiographic technique.
Thursday, February 4, 2016

13. METHODS BASED ON FICK’S
PRINCIPLE
 Fick’s principle –
Amount of substance
taken up by an organ
per unit of time (Q) is
equal to the arterial
level of the substance
(A) – venous level of
substance (V) × Blood
flow(F)
 Q = (A-V) F
 F = Q
-------
(A-V)
 2 methods
 Direct
 Indirect
Thursday, February 4, 2016

14. METHODS BASED ON FICK’S
PRINCIPLE
Thursday, February 4, 2016

15. DIRECT METHOD.
 Principle – pulmonary
blood flow = Rt
ventricular blood flow = Lt
ventricular blood flow.
 Pulmonary blood flow =
amount of O2 taken by
lungs
-------------------------------
PVO2-PAO2
 Amount of O2 taken
determined by
spirometer.
 PVO2 – from any
peripheral artery
 PAO2 – from
pulmonary artery.
Thursday, February 4, 2016

16. DIRECT METHOD.
 Pulmonary blood flow =
amount of O2 taken by
lungs
-------------------------------
PVO2-PAO2
 CO = 2000/ (200-160) ×
100
 CO = 5000ml/min
 Disadvantages.
 Invasive, risk of
infection &
hemorrhage.
 Pt is conscious so CO is
more than normal
 Complications –
ventricular
fibrillations.
Thursday, February 4, 2016

17. DIRECT METHOD.
Thursday, February 4, 2016

18. INDIRECT METHOD.
 Same as direct
method only
 CO2 excretion by lungs
is measured by
spirometry.
 PACO2 from alveolar
air.
 PVCO2 – Rebreathing
into closed bag.
 CO = CO2 output/min
----------------------
PACO2-PVCO2
Thursday, February 4, 2016

19. INDICATOR OR DYE DILUTION
METHOD.
 Principle – Known
amount of dye injected
into Rt atrium & mean
concentration of its
first passage through
an artery is
determined.
 Blood flow (F)= Q/Ct
 F = blood flow in
L/min.
 Q= quantity of dye
injected.
 C = Mean Conc. of dye.
 T = Time duration in
sec of first passage of
dye.
Thursday, February 4, 2016

20. IDEAL INDICATOR.
 Should be nontoxic.
 Mix evenly.
 Easy to measure.
 Not alter cardiac output
or haemodynamic.
 Not be changed by
body.
 E.g. Evan’s blue,
radioactive isotopes.
Thursday, February 4, 2016

21. PROCEDURE.
 5 mg of Evan’s blue dye
mixed with venous blood.
 Duration of first passage
of dye(t) & mean conc of
dye (C) in arterial blood
estimated.
 CO= Q/ct × 60 = 5/1.5L
×40 × 60 = 5 L/min
Thursday, February 4, 2016

22. THERMODILUTION
 PRINCIPLE – same as
indicator dye dilution
method except cold
saline is used.
 Resultant change in
blood temperature in
pulmonary artery is
determined.
Thursday, February 4, 2016

23. INHALATION OF INERT GASES.
 NO, Acetylene – used.
 Pulmonary blood flow
is determined from
following values
 Quantity of gas
absorbed in given time.
 Partial pressure of gas
in alveolar air.
 The solubility of gas.
Thursday, February 4, 2016

24. PHYSICAL METHODS
 Doppler
echocardiography –
 Ultrasonic evaluations
of cardiac functions.
 B-scan ultrasound at a
frequency of 2.25 MHz
using a transducer.
 Measure EDV, ESV,CO
& Valvular defects.
Thursday, February 4, 2016

25. Thursday, February 4, 2016

26. PHYSICAL METHODS
 Ballistocardiography
 Graphical record of the
pulsations created due
to ballistic recoil of the
pumping heart.
Thursday, February 4, 2016

27. PHYSICAL METHODS
 CINERADIOGRAPHIC
TECHNIQUE.
 The making of a motion
picture record of successive
images appearing on a
fluoroscopic screen.
 Radiography of an organ in
motion, for example, the
heart, the gastrointestinal
tract.
Thursday, February 4, 2016

28. VARIATIONS IN CARDIAC
OUTPUT.
 Physiological causes.
 Age – CI children >
adult.
 Sex – females > Males
 Diurnal variations-
low in early morning.
 Environmental
temperature – direct
relation.
 Anxiety excitement,
Eating, Exercise,
Pregnancy, High
altitude – direct
relation.
 Posture change –
sitting or standing >
lying down due to
venous pooling.
Thursday, February 4, 2016

29. VARIATIONS IN CARDIAC
OUTPUT.
 Pathological – its
mainly due to low
peripheral resistance
 Increase
 Fever
 Anemia.
 Hyperthyroidism.
 Beriberi
 Arteriovenous fistula
Thursday, February 4, 2016

30. VARIATIONS IN CARDIAC
OUTPUT.
 Decrease
 CCF
 Rapid arrhythmias
 Cardiac shock
 Incomplete heart block
 Hemorrhage
 Hypothyroidism.
Thursday, February 4, 2016

31. Thank you.
Thursday, February 4, 2016