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