oxygenation in patients with exceptionally high oxygen demand - and the role of hemotherapy
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Oxygenation in patients with exceptionally high oxygen demand - and the role of hemotherapy. Problem An increased oxygen demand reflects an increased overall metabolism - useful or not. An increased oxygen demand is often seen in patients with severe circulatory impairment. - PowerPoint PPT PresentationTRANSCRIPT
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
Bengt GerdinBengt Gerdin
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.
Bengt GerdinBengt Gerdin
TerminologyTerminology
Oxygen demand/consumptionOxygen demand/consumption VOVO22
Oxygen transportOxygen transport DODO22
Oxygen extraction rateOxygen extraction rate OO22ERER
Bengt GerdinBengt Gerdin
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))
Bengt GerdinBengt Gerdin
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
Bengt GerdinBengt Gerdin
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
Bengt GerdinBengt Gerdin
Oxygen demand/consumption VOOxygen demand/consumption VO22
ml/min/m2
At rest 125 Leisure 160 Trauma 200 Sepsis >250
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Oxygen extraction rateOxygen extraction rate OO22ERER
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 %
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Oxygen extraction rateOxygen extraction rate OO22ERER
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
Bengt GerdinBengt Gerdin
Oxygen demand/consumption VOOxygen demand/consumption VO22
ml/min/m2
At rest 125 Leisure 160 Trauma 200 Sepsis >250
Bengt GerdinBengt Gerdin
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
Bengt GerdinBengt Gerdin
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??????
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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
Bengt GerdinBengt Gerdin
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
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DODO22
VO
VO
22 Aerobic metabolismAerobic metabolismAnaerobic Anaerobic metabolismmetabolism
Critical Critical DODO22
DODO2 2 -dependent-dependent DO DO22 -independent -independent
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DODO22
VO
VO
22 Aerobic metabolismAerobic metabolismAnaerobic Anaerobic metabolismmetabolism
Critical Critical DODO22
DODO2 2 -dependent-dependent DO DO22 -independent -independent
---- normal normal
---- sepsis sepsis
Bengt GerdinBengt Gerdin
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
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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
Bengt GerdinBengt Gerdin
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
Bengt GerdinBengt Gerdin
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?)?)