Defining Optimal Perfusion during CPB · It is a device able to monitor in a real time vital...

Carlo Alberto Tassi Marketing Manager Eurosets Italy

Defining Optimal Perfusion during CPB

It is a device able

to monitor in a real time vital parameters and able to provide

information regarding the transport and

the consumption of oxygen during

the extra corporeal circulation

LANDING PERMITS THE DISPLAY OF

21 PARAMETERS WITH VALUES UPDATED EVERY 5 SECONDS

What is the State of the Art?

1953 John Gibbon MD

First intervention been successful thanks to the extra-corporeal circulation

Since then, control of gas exchange and acid-base has always been done by reading and interpreting data from a device called GAS ANALIZER

What is the Gas Analizer (GA) intended for?

The GA is an extemporaneous test that is done through a blood test usually arterial, which is scanned rapidly through a special laboratory instrument.

The GA allows to measure the following parameters:

Related to ventilation and gas exchange

Related to acid-base balance and metabolism

Related to plasma electrolytes

MORBIDITY and MORTALITY Patient undergoing cardiac surgery with Cardio

Pulmonary By-Pass

Acute renal failure: incidence 1-5% mortality 50%

gastro-intestinal Ischemia: complications from 0.3 to 2%

mortality 12-67%


Pulmonary By-Pass

Brain damage or reversible in the first week: 50% incidence


Pulmonary By-Pass

- Severe disability or death from cerebral stroke: 1-5% incidence


Pulmonary By-Pass

Main Controversy related to perfusion and oxygenation during CPB

The GA with ventilation and gas exchange parameters:

1. Provides information related to the diffusion of oxygen in the lung tissue;

2. It does not provide adequate quantitative information on the O2 transport and especially relating to the O2 consumption at tissue site.

It is common practice to calculate the theoretical flow of heart-lung machine using the following coefficient calculation:

Q = B.S.A. x 2.4 (lt/min/m2)

This condition does not take in consideration the CURRENT metabolic needs as well as having individual characteristics, can change several times during surgery.

Main Controversy related to perfusion and oxygenation during CPB

WHAT CAN WE DO?

1 gr di Hb binds 1.36 ml di O2/dl.

considering Hb= 15 gr/dl, The O2 trasport will be 20 ml/dl.

IMPORTANCE of Hb

The hemoglobin (Hb) is a protein contained within red blood cells

working as O2 carrier to transport O2all tissues.

The 98% oxygen is transported through the hemoglobin (Hb). The 2% oxygen is transported dissolved in the plasma. The amount of Hb saturated oxygen (SO2) increases gradually with increasing PO2 with a typical “sigmoidal pattern”.

O2 dissociation curve

The term PARTIAL PRESSURE (P) indicates the pressure exerted by a single gas in a gas

mixture or in a liquid (Dalton's Law).

Cardiac output (CO) in a man of medium height at rest is about 5 l / min. Under conditions of physical exertion the C.O. can increase up to 30-35 liters / min. to meet the increased oxygen consumption of muscles. The oxygen consumption appears to be an individual factor primarily related to the type of metabolism of the individual.

O2 requirement in the tissue

Relationship between consumption and supply of

oxygen.

STD Value (SvO2): 60-80%

O2 Saturation (SVO2)

The oxygen consumption of a patient undergoing Cardiac Surgery corresponds to :

sleeping? running?

Controversial related to O2 requirement

The cellular activities require energy in the form of oxygen.

If oxygen availability is limited alterations in metabolic functions occur with organ dysfunction, which if prolonged over time may become irreversible (hypoxic).

To ensure proper functioning of cellular activities it is necessary a perfect balance between transport and consumption of oxygen.

O2 TRANSPORT =

DO2

O2 CONSUPTION

= VO2

CELLULAR METABOLISM

Different approach to CPB

The amount of O2 available to the cells (DO2) is determined by the following factors: 1.RESPIRATORY SYSTEM which must ensure adequate arterial O2

saturation (SaO2 = 98-100%). 2.Concentration of HEMOGLOBIN (Hb). 1 g Hb binds 1:36 O2/dl ml. If

we consider Hb = 15 g / dl, the transport of O2 will be 20 ml / dl. 3.CARDIAC OUTPUT (CO ml / min) ensures the transport of O2 in the

blood. C.O. / B.S.A. = Cardiac Index (CI ml/min/m2) If we consider CO = 5 l / min, the total transport of O2 is 1000 ml / dl 4.SYSTEMIC VASCULAR RESISTANCE (SVR sec/cm5/m2 dyne *) represent the change in peripheral vascular tone. Together with the C.O. constitute the system to change the blood

pressure. They regulate the peripheral microcirculation.

hints of Physiology

We should guarantee an adequate oxygen transport to tissues (DO2),to meet cells demands (VO2), through a direct action following factors:

1.  Ensuring adequate blood oxygenation

2.  Cardiac Output appropriate to the need

3.  Increase the hemoglobin level 4.  Adjustment of systemic vascular

resistance 5.  Temperature adjustment

How to prevent the Cell damage during CPB?

Thanks to the sensors equipping LANDING monitor, it is possible to measure and calculate the following parameters:

Oxygen Delivery Index DO2i = (0,0138 x Hb x SaO2) x C.I. x 10 (ml/min/m2) Oxygen Consumption Index VO2i = ((0,0138 x Hb x SaO2) – (0,0138 x Hb x SvO2)) x C.I.x10 (ml/min/m2) Oxygen Extraction Index O2ERi = (SaO2 - SvO2) / SaO2 x100 (ml/m’/m2) Sistemic Vacular Resistance Index SVRi = MAP / C.I. X 80 dyne*sec/cm5/m2

LANDING = Fick’s law

DO2 has to be evaluated as func3on of Hct ONLY if the flow is constant!!

DEEP HAEMODILITUION à lower DO2

à  lower O2 supply to organ à  increasing post-operative morbidity

DO2 and HCT

Hb

amount of oxygen used by the cells to satisfy

the organism metabolic demand

*CvO2= ( x 1,34 x SvO2) + (0,0031x PvO2)

VO2 = CO x (CaO2-‐CvO2*)

[ml/kg/min]

O2 CONSUMPTION (VO2)

If the CONTRIBUTION of OXYGEN (DO2) goes LOWER, with constant metabolism (VO2), the tissues increase the EXTRACTION OF OXYGEN

Represents the fraction of oxygen extracted from the tissues

O2ER = VO2/DO2 (approx 25%)

O2 EXTRACTION (O2ER)

ARTERY VEIN

PaO2 100mmHg PvO2 40 mmHg

SaO2 100 % SvO2 75 %

CaO2 20 ml/dl CvO2 15 ml/dl

O2 EXTRACTION in the TISSUE

ARTERY VEIN


SaO2 100 % SvO2 60 %


LOWER CARDIAC OUTPUT


ARTERY VEIN


SaO2 100 % SvO2 60 %


VO2 INCREASING


ARTERY VEIN


SaO2 100 % SvO2 65 %


ANEMIA


ARTERY VEIN

PaO2 48 mmHg PvO2 32 mmHg

SaO2 80 % SvO2 55 %


RESPIRATORY FAILURE


ARTERY VEIN


SaO2 100 % SvO2 88 %


REDUCED CONSUMPTION (anesthesia, hypothermia, curarization, SHUNT A-V)

O2 EXTRACTION DURING CPB

The O2 transport depends to following parameers: 1. CARDIAC INDEX 2. Hb 3. ARTERIAL SATURATION SaO2 DO2i = (0,0138 x Hb x SaO2) x C.I. x 10 (ml/min/m2) ≥ 270ml/min/m2

To increase the DO2 :

↑C.I ***** ↑Hb *** SaO2*

DO2i Oxygen Delivery Index

The Oxygen transpot depends on: •  CARDIAC INDEX •  Difference between ARTERIAL and VENOUS O2 CONTENT VO2i = ((0,0138 x Hb x SaO2) – (0,0138 x Hb x SvO2)) x C.I.x10 (ml/min/m2) = 1/4 - 1/5 of DO2

It is not possible direct action to change the VO2 A low VO2 value can be linked to: 1.  tissue hypoxia 2.  reduced oxygen demand without presence of hypoxia.

VO2i Oxygen Consumption Index

Both the DO2 VO2 when taken individually, they give poor information about the metabolic status of the patient. The O2ERi (ratio DO2/VO2), correlates the O2 transport with O2 consumption , thus, O2ERi expresses the ability of tissues to consume the available oxygen. O2ERi = (SaO2 - SvO2) / SaO2 x100 (ml/m’/m2) = 20-25%

O2ERi Oxygen Extraction Index

On what parameters can perfusionist work? 1.  Change in Cardiac Output / Cardiac Index 2.  Eventually increasing the hemoglobin (Hb) 3.  Ensuring adequate oxygenation (PaO2/SaO2) 4.  Control of body temperature. 5.  Regulation of peripheral vascular resistance BALANCE of these parameters allows to obtain optimal O2ERi guaranteeing a proper perfusion

even at the periphery.

Does DO2/VO2 can be optimized?

Under physiological conditions the O2 transport is adjusted to provide the adequate to O2 required.

The oxygen consumption (VO2) is about 25% of DO2, and all the energy produced comes from "aerobic metabolism".

When the metabolic demand increases, physiological mechanisms starts to increase either DO2 either the extraction fraction (O2ER).

In the event of DO2 reduced, the CONSUMPTION is kept constant thanks to an increase of the O2ER, but the VO2 begins to decrease and the energy required can be produced only through

the anaerobic metabolism.

Inadeguate DO2/VO2à cell suffering and Lactate production

DO2 / VO2

0 100 200 300 400 500 600 700 800 900 1,000 DO2 (ml/min)

VO2 (ml/min)

80 70 60 50 40 30

SvO2 (%)

250 200 150 100 50 0

70 60 50 40 30 25 20 0

DO2 Indipendency

O2 ER (%)

DO2 CriHcal

DO2 Dipendency

The DO2 in the plateau phase is independent of VO2 When exceeds the critical point (anaerobic threshold)

the DO2 and VO2 becomes dependent and the Do2 value decreases rapidly

DO2 / VO2 Versus LACTATE

0 100 200 300 400 500 600 700 800 900 1,000 DO2 (ml/min)

VO2 (ml/min)

80 70 60 50 40 30

SvO2 (%)

250 200 150 100 50 0

12 10 8 6 4 2 0

DO2 Indipendency

Lac (mMol/L) DO2 CriHcal

DO2 Dipendency

HYPERLACTATEMIA

In the case of strenuous exercise, or pathological conditions (sepsis, shock, heart failure) if the oxygen consumption (VO2) exceeds the transport (DO2) the production of lactic Lactate starts.

Hyperlactatemia Lac>3mMoli(L

Is an index of tissue hypoxia from inadequate perfusion (circulatory failure, cardiac shock, severe anemia).

Numerous studies have shown an inverse correlation between the level of lactate and survival of critically ill patients. Recent studies have confirmed these results with association between an early increase in lactate and development of MOF (Multi Organ Failure).

The duration and degree of hyperlactatemia are important predictors of morbidity and mortality.

Hyperlactatemia remains therefore a reliable indicator for prognosing cellular suffering.

Hyperlactatemia Lac> 3mMoli/L

New approach to C.P.B.

TAYLORED CPB

Leteratures on DO2

Ranucci M, Pavesi M, Mazza E, et al: Risk factors for renal dysfunction after coronary surgery: the role of cardiopulmonary bypass technique. Perfusion 9: 319-326, 1994.

Fang WC, Helm RE, Krieger KH, et al. Impact of minimum hematocrit during cardiopulmonary bypass on mortality in patients undergoing coronary artery surgery. Circulation. 1997 Nov 4;96(9 Suppl):II-194-9.

DeFoe GR, Ross CS, Olmstead EM, et al Lowest hematocrit on bypass and adverse outcomes associated with coronary artery bypass grafting. Northern New England Cardiovascular Disease Study Group. Ann Thorac Surg. 2001 Mar;71(3):769-76.

Swaminathan M, Phillips-Bute BG, Conlon PJ, et al: The association of lowest hematocrit during cardiopulmonary bypass with acute renal injury after coronary artery bypass surgery. Ann Thorac Surg 76: 784-792, 2003.

Habib RH, Zacharias A, Schwan, et al. Adverse effects of low hematocrit during cardiopulmonary bypass in the adult: should current practice be changed? J Thorac Cardiovasc Surg. 2003 Jun;125(6):1438-50.

Karkouti K, Beattie WS, Wijeysundera DN, et al. Hemodilution during cardiopulmonary bypass is an independent risk factor for acute renal failure in adult cardiac surgery. J Thorac Cardiovasc Surg 2005; 129: 391-400.

Habib RH, Zacharias A, Schwann, TA, et al. Role of Hemodilutional Anemia and Transfusion during Cardiopulmonary Bypass in Renal Injury After Coronary Revascularization: Implications on Operative Outcome Crit Care Med (in press)

SaO2 Hgb

DO2 >270 ml/min/m2

PUMP FLOW “TAILORED”

FLOW

DO2

TAYLORED CPB

Main GOAL: DO2 > 270 ml/min/m2

Calculated DO2= (1,34 x Hgb x SatA x Qb/100 ) / BSA

Increase Flow

DO2 >270ml/min/m2 ? Hct >25% ?

NO

a.   Diuretic b.  Haemofiltration c.   Transfusion

YES

If Lactate > 2mmol/l Attention to: Flow, Hgb, Arterial Pressure, Temperature, Glycemia

Continue CPB wthout

adjustment

LANDING allows to DISPLAY 21

PARAMETERS with VALUES UPDATED EVERY 5 SECONDS

Monitor 10.5 inch touch screen Probes Arterial and Venous

Fllow meter ultrasonic Inteface cables for pressure transducer

LANDING items

LANDING: main screen

Measured

Calculated

LANDING: Body Surface Area calculation

LANDING: working mode

DO2i

VO2i

O2ERi

weaning

LANDING “non invasive” A-V probes

LANDING: select a screen

LANDING: modifiable screen

LANDING: during CPB

LANDING: story board

LANDING: select parameters to Show, H-Y

LANDING: alarm setting

LANDING: value fine tuning

LANDING download data via USB

DO2

VO2

TAHE HOME MESSAGE

Defining Optimal Perfusion during CPB

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