Oxygen Transport in Exercise

Prof. Dr. Alfred Hager Department of Pediatric Cardiology

and Congenital Heart Disease

Head of Outpatient Section

Head of Exercise Laboratory

Member of DGPK Guideline Committee

Conflicts of Interests

Institutional

• Contribution to clinical trials: Actelion, Medtronic, Edwards, Occlutec, Novartis,

Lilly

• Unrestricted grants for investigator initiated trials: Pfizer, GlaxoSmithKline,

Abbott, Actelion

Private

• Shareholder: Celgen, Gilead, Vertex, Abbvie, Pfizer, Novartis, Johnson &

Johnson, Amgen, Cerner, Lilly, Baxter, Merck, Biogen, …

• Advisory board reimbursement: Actelion

• Speakers reimbursement: Schiller, Actelion, Abbott, Pfizer, Encysive, AOP

Orphan, OMT, GlaxoSmithKline, Medtronic

• Travel expense reimbursement: Pfizer, GlaxoSmithKline, AOP Orphan

Pharmaceuticals, Lilly, Actelion, Medtronic, Arrows, Guidant, Fresenius

Oxygen Transport

ventilation

diffusion

lung perfusion

heart

muscle perfusion

diffusion

metabolism

O2 CO2

Mito.

Fick‘s Principle

flow = indicator uptake / concentration change

O2

CpaO2 CpvO2 blood flow

blood flowpulmonary = oxygen uptake / (CpvO2 - CpaO2)

blood flowsystem = oxygen consumption / oxygen content change

Fick‘s Principle

O2

CaO2 CvO2 blood flow

oxygen consumption = blood flowsystem · oxygen content change

Oxygen consumption (VO2)

= blood flowsystem · oxygen content change

= cardiac output (Qs) · 0.0136 · Hb · (SaO2 – SvO2)

= heart rate · stroke volume · 0.0136 · Hb · (SaO2 – SvO2)

= HR · EF · LVVed · 0.0136 · Hb · (SaO2 – SvO2)

.

chronotropy systolic

function

diastolic

function

O2 transport

capacity O2 extraction

.

Oxygen uptake (VO2)

7

= blood flowsystem · oxygen content change

= cardiac output (Qs) · 0.0136 · Hb · (SaO2 – SvO2)

= heart rate · stroke volume · 0.0136 · Hb · (SaO2 – SvO2)

= HR · EF · LVVed · 0.0136 · Hb · (SaO2 – SvO2)

.

chronotropy systolic

function

diastolic

function

O2 transport

capacity O2 extraction

.

Oxygen Cost for Work

Wassermann, 4. Aufl. 2005

Oxygen

upta

ke

(ml/

min

)

17 healthy subjects

Oxygen uptake

Heart rate – VO2 .

= oxygen uptake / heart rate

( = „ oxygen transport / heart beat “ )

= HF · EF · LVVed · 0.0136 · Hb · (SaO2 – SvO2)

= stroke volume · oxygen content change

×

Oxygen Pulse

Oxygen Pulse

Cardiac Work

Energy = P · V

Work = dP · dV

Ventricular Volume (ml)

Herzarbeit (Cardiac Work)

Energy = P · V

Work = dP · dV

Ventricular Volume (ml)

Cardiac Work =

stroke volume ·

(“mean SBP” – “mean diastolic left ventricular pressure”)

≈

stroke volume · SBP

= work / time (= W)

= heart rate · cardiac work

≈ heart rate · stroke volume · SBP

= cardiac output · SBP

VO2 = cardiac volume · oxygen content change

Cardiac Power

.

.

= cardiac output · oxygen content change · SBP

(= oxygen uptake · SBP)

(= cardiac power · oxygen content change)

= HF · EF · LVVed · 0.0136 · Hb · (SaO2 – SvO2) · RR

Circulatory Power

peakSBP, Circulatory Power and oscillatory breathing

are the best predictors

Circulatory Power

circulatory work circulatory power

O2 pulse O2 uptake

cardiac work cardiac power

stroke volume cardiac output

× HR

×

O2 transport

capacity

×

O2 extraction

× BP

CPET Cube

Limitations of the Model

• Mitral / aortic valve regurgitation: stroke volume ≠ effective aortic stroke volume

• Cardiac work with only SBP (without volume pressure loops) ?

• Cardiac work without right ventricular work ?

• In congenital heart defects with shunts there is not a single cardiac output: QP, QS

• What is the physical background of „circulatory power / work“ (gas flow · BP) ?

. .

Limitations of the Model

• Mitral / aortic valve regurgitation: stroke volume ≠ effective aortic stroke volume

• Cardiac work with only SBP (without volume pressure loops) ?

• Cardiac work without right ventricular work ?

• In congenital heart defects with shunts there is not a single cardiac output: QP, QS

• What is the physical background of „circulatory power / work“ (gas flow · BP) ?

. .

only oxygen pulse and oxygen uptake

are reliable for all patients