Oxygenation in patients with exceptionally high oxygen demand - and the role of hemotherapy

Bengt GerdinBengt Gerdin

Oxygenation in patients with Oxygenation in patients with exceptionally high oxygen demand exceptionally high oxygen demand

- and the role of hemotherapy- and the role of hemotherapy


ProblemProblem

An increased oxygen demand reflects an An increased oxygen demand reflects an increased overall metabolism - useful or not.increased overall metabolism - useful or not.

An increased oxygen demand is often seen in An increased oxygen demand is often seen in patients with severe circulatory impairment.patients with severe circulatory impairment.

An increased oxygen demand must be An increased oxygen demand must be matched by an adequate oxygen transport.matched by an adequate oxygen transport.


TerminologyTerminology

Oxygen demand/consumptionOxygen demand/consumption VOVO22

Oxygen transportOxygen transport DODO22

Oxygen extraction rateOxygen extraction rate OO22ERER


Cardiac output 5000 ml/min x x

Arterial oxygen saturation

95/100

x x Hemoglobin

concentration 15/100 g/ml

x x Oxygen combining

capacity of hemoglobin

1,39 (1,31) ml/g

= = Oxygen flux 1000 ml/min

Oxygen transport / Oxygen flux (DOOxygen transport / Oxygen flux (DO22))


Cardiac output 5000 ml/min x x

Arterial oxygen saturation

95/100

x x Hemoglobin

concentration 15/100 g/ml

x x Oxygen combining

capacity of hemoglobin

1,39 (1,31) ml/g

= = Oxygen flux 1000 ml/min

Arterial oxygen content (CaO2)Arterial oxygen content (CaO2)

=20/100 ml O2

/ml blood

= 0,2 ml O2

/ml blood


Oxygen consumption (VOOxygen consumption (VO2)2)

Amount of oxygen transported out to the tissues Amount of oxygen transported out to the tissues minusminus

amount of oxygen transported back to the heart.amount of oxygen transported back to the heart.

OutOut CO x SaOCO x SaO22% x Hb x 1.39% x Hb x 1.39

BackBack CO x SvOCO x SvO22% x Hb x 1.39% x Hb x 1.39

VOVO22 = CO x (SaO = CO x (SaO22% - SvO% - SvO22%) x Hb x 1.39%) x Hb x 1.39


Oxygen demand/consumption VOOxygen demand/consumption VO22

ml/min/m2

At rest 125 Leisure 160 Trauma 200 Sepsis >250



Relative amount of oxygen extracted from the Relative amount of oxygen extracted from the blood during one passage through the tissues.blood during one passage through the tissues.

OutOut CO x SaOCO x SaO22% x Hb x 1.39% x Hb x 1.39

BackBack CO x SvOCO x SvO22% x Hb x 1.39% x Hb x 1.39

OO22ER ER ≈ (SaO ≈ (SaO22% -SvO% -SvO22%)/SaO%)/SaO22% x 100% x 100

Example: SaO2 = 95 % and SvO2 = 70 %gives O2ER ≈ (95-70)/95 = 26 %



Varies in different vascular bedsVaries in different vascular beds

Highly extracting beds:Highly extracting beds:liverlivergut mucosagut mucosahippocampushippocampus

Global OGlobal O22ER is about 25 %, i.e. DOER is about 25 %, i.e. DO22/VO/VO22 is about 4:1 is about 4:1

Bengt GerdinBengt GerdinFrom Nunn JF, Applied Respiratory Physiology

Bengt GerdinBengt GerdinFrom Vincent JL et al. In: Pathophysiology of Shock, Sepsis and From Vincent JL et al. In: Pathophysiology of Shock, Sepsis and

Organ Failure, Ed Schlag & Redl, Springer, 1993Organ Failure, Ed Schlag & Redl, Springer, 1993


Oxygen demand/consumption VOOxygen demand/consumption VO22

ml/min/m2

At rest 125 Leisure 160 Trauma 200 Sepsis >250


How do we know that oxygen How do we know that oxygen transport is adequate?transport is adequate?

Global vs local assessmentGlobal vs local assessment


How do we know that oxygen How do we know that oxygen transport is transport is adequateadequate??

Global vs local assessmentGlobal vs local assessment

Adequate whereAdequate where??????


Global assessment of adequacy of oxygen Global assessment of adequacy of oxygen transporttransport

•Blood lactateBlood lactaterelated to survival in sepsisrelated to survival in sepsis

•Oxygen saturation in mixed venous bloodOxygen saturation in mixed venous blood


Local assessment of adequacy of oxygen Local assessment of adequacy of oxygen transporttransport

Hypothesis: Deficient oxygen transport to a certain Hypothesis: Deficient oxygen transport to a certain vascular bed is related to success of therapyvascular bed is related to success of therapy

Liver? Liver? Gut?Gut?Brain?Brain?

Gut tonometryGut tonometryLiver vein SOLiver vein SO22


DODO22

VO

VO

22 Aerobic metabolismAerobic metabolismAnaerobic Anaerobic metabolismmetabolism

Critical Critical DODO22

DODO2 2 -dependent-dependent DO DO22 -independent -independent


DODO22

VO

VO

22 Aerobic metabolismAerobic metabolismAnaerobic Anaerobic metabolismmetabolism

Critical Critical DODO22

DODO2 2 -dependent-dependent DO DO22 -independent -independent

---- normal normal

---- sepsis sepsis


General strategy:General strategy:

Improve oxygen transport;Improve oxygen transport;

When in doubt: determine!When in doubt: determine! ( (COCO and and OO22ER)ER)

CO↑CO↑Hb↑Hb↑ optimal viscosity (Hct close to 33) optimal viscosity (Hct close to 33) BV↑BV↑CVP (LAP) ↑CVP (LAP) ↑vasoactive aminesvasoactive amines


Burn injuryBurn injury

Massive activation of all cascade systems Massive activation of all cascade systems

Major effects of circulating and locally acting cytokines Major effects of circulating and locally acting cytokines

Major metabolic consequences, oxygen demand may Major metabolic consequences, oxygen demand may increase to 200-300 %increase to 200-300 %

cytokine effects SIRScytokine effects SIRScompensation for heat losscompensation for heat loss


Strategy for adequate oxygenation in Strategy for adequate oxygenation in burnsburns

Diminish oxygen consumptionDiminish oxygen consumptiondiminish water lossdiminish water lossdiminish heat lossdiminish heat lossdiminish shiveringdiminish shiveringdiminish feverdiminish fever

Optimize oxygen transportOptimize oxygen transport


How to monitor the acute intravenous How to monitor the acute intravenous treatment?treatment?

The dream is to monitor by the parameter that gives the best The dream is to monitor by the parameter that gives the best information about the patient´s condition after 24 hours.information about the patient´s condition after 24 hours.

-least risk for organ ischemia (e.g. kidneys)-least risk for organ ischemia (e.g. kidneys)- least risk for bacterial translocation- least risk for bacterial translocation- least risk for causing progression of the burn- least risk for causing progression of the burn

Circulatory parameter (CVP?, MAP?, HR<120?)Circulatory parameter (CVP?, MAP?, HR<120?)Oxygen transport parameter (SaOOxygen transport parameter (SaO22?)?)

Kidney perfusion parameter (hourly urinary output?)Kidney perfusion parameter (hourly urinary output?)Other metabolic parameter (blood lactate?)Other metabolic parameter (blood lactate?)Gut perfusion parameter (pHGut perfusion parameter (pHii?)?)

Oxygenation in patients with exceptionally high oxygen demand - and the role of hemotherapy

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