cardiopulmonary bypass

Cardiopulmonary Cardiopulmonary bypassbypass

Abeer El NakeraAbeer El Nakera

Lecturer of anesthesiaLecturer of anesthesia

Zagazig universityZagazig university

objectivesobjectives

•To know goals of CPBTo know goals of CPB

•To know basic components of To know basic components of CPBCPB

•How to initiate CPBHow to initiate CPB

•Management of CPBManagement of CPB

Immediately before bypassImmediately before bypass

Historical perspectiveHistorical perspective

• The fifth anniversary of the first The fifth anniversary of the first successful use of CPB was successful use of CPB was celebrated in 2003celebrated in 2003

Goals of CPBGoals of CPB

The CPB circuit has 4 major The CPB circuit has 4 major functions:functions:

Oxygenation and carbon dioxide Oxygenation and carbon dioxide eliminationelimination

Circulation of bloodCirculation of blood

Systemic cooling and rewarmingSystemic cooling and rewarming

Diversion of blood from the heart Diversion of blood from the heart to provide bloodless surgical fieldto provide bloodless surgical field

Basic components of CPBBasic components of CPB

1.1.A venous reservoirA venous reservoir

2.2.An oxygenator An oxygenator

3.3.A heat exchanger A heat exchanger

4.4.The main pumpThe main pump

5.5.An arterial filter An arterial filter

6.6.Accessory pumps and devicesAccessory pumps and devices

CPBCPB


The primary fluid (hemodilution):The primary fluid (hemodilution):As preparation for CPB conductAs preparation for CPB conduct

• Must be devoid of air bubblesMust be devoid of air bubbles• Volume : 1500 _ 2000 mlVolume : 1500 _ 2000 ml

components :components :• a balanced salt solutiona balanced salt solution ( blood in anemic and ( blood in anemic and

pediatric pts.)pediatric pts.)• ColloidColloid• MannitolMannitol• bicarbonatebicarbonate


The primary fluid (hemodilution):The primary fluid (hemodilution): Effects :Effects :

1.1. Decreased blood viscosityDecreased blood viscosity…………improve improve microcirculationmicrocirculation

2.2. Decrease metabolic acidosisDecrease metabolic acidosis3.3. Increase UOPIncrease UOP4.4. Decrease blood demandDecrease blood demand5.5. Decrease the incidence of hepatitis Decrease the incidence of hepatitis

and Aids associated with blood and Aids associated with blood transfusion transfusion


The primary fluid (hemodilution):The primary fluid (hemodilution): disadvantages :disadvantages :

1.1. Decrease of O2 carrying capacityDecrease of O2 carrying capacity

2.2. Postoperative EC fluid overloadPostoperative EC fluid overload…….. .. Increase the risk of pulmonary edemaIncrease the risk of pulmonary edema

3.3. HypotensionHypotension…….. Due to decreased SVR.. Due to decreased SVR

4.4. Decrease the concentration of Ca , Mg Decrease the concentration of Ca , Mg , phosphate and zinc, phosphate and zinc


Venous reservoirVenous reservoir::• It receives blood from It receives blood from

the right atrium via one the right atrium via one or two venous cannulas or two venous cannulas by by the effect of the effect of gravitygravity

• Factors affecting blood Factors affecting blood flow toflow to reservoir:reservoir:

1.1. Venous pressure Venous pressure …….normally low .normally low …….little .little effecteffect

2.2. The height between the The height between the pt. and reservoirpt. and reservoir

3.3. The resistance of The resistance of cannulae and tubing cannulae and tubing systemssystems

4.4. Priming the machine Priming the machine creates siphon effectcreates siphon effect


Venous reservoir:Venous reservoir:• Precautions:Precautions:

1.1. Air lockAir lock can prevent blood flow can prevent blood flow

2.2. The fluid level in the reservoir is The fluid level in the reservoir is criticalcritical

3.3. Low reservoir level can lead to Low reservoir level can lead to fatal fatal airair embolismembolism


Oxygenator :Oxygenator :• Blood is drained from the bottom of Blood is drained from the bottom of

venous reservoir to the oxygenatorvenous reservoir to the oxygenator• Function: blood equalibration with gas Function: blood equalibration with gas

mixture, addition of CO2 and volatile mixture, addition of CO2 and volatile anestheticsanesthetics

• TypesTypes : : membrane( gas permeable silicon membrane( gas permeable silicon

membranemembrane bubble bubble


Heat exchanger:Heat exchanger:Function : Function :

Cooling and Cooling and rewarmingrewarmingTemperature of Temperature of

water in the water in the exchanger range exchanger range from 4 from 4 –– 42 42

Heat transfer by Heat transfer by conductionconduction


The main pumpThe main pump::o Types :Types :

1.1. Roller Roller 2.2. CentrifugalCentrifugal3.3. PulsetilePulsetile

o Pulsetile pump is more physiologic :Pulsetile pump is more physiologic :Better oxygenation, decrease SVR , less Better oxygenation, decrease SVR , less

stress hormones ,better cerebral and stress hormones ,better cerebral and renal perfusionrenal perfusion


Arterial filterArterial filter::To prevent systemic embolisationTo prevent systemic embolisation

Accessory pumps and devices:Accessory pumps and devices:1.1. Cardiotomy suction:Cardiotomy suction:

Excessive suction lead to excessive RBCs Excessive suction lead to excessive RBCs traumatrauma

Excessive suction to cell saverExcessive suction to cell saver…….. Blood .. Blood volume depletionvolume depletion


2.2. Left ventricular vent:Left ventricular vent:Source of blood accumulating in the Source of blood accumulating in the

heart during surgery:heart during surgery:

o Physiologic shuntPhysiologic shunto Aortic regurge either structural or Aortic regurge either structural or

iatrogeniciatrogenico Extracardiac lt. to rt. Shunt eg. Extracardiac lt. to rt. Shunt eg.

PDAPDA


2.2. Left ventricular vent:Left ventricular vent:Venting is important to Venting is important to

avoid Lt. vent. avoid Lt. vent. DistensionDistension

Site of Lt. ventricular Site of Lt. ventricular venting:venting:

• Catheter in Lt. Catheter in Lt. ventricle via right ventricle via right superior pulmonary superior pulmonary vein,LV vein,LV apex,cardioplegia apex,cardioplegia cannulacannula

Blood aspirated by Blood aspirated by vent pump is returned vent pump is returned to venous reservoirto venous reservoir


3.3. Cardioplegia pump:Cardioplegia pump:Optimum control of Optimum control of

infusion pressure, infusion pressure, rate and rate and temperaturetemperature

• Hem-ultra-filtration:Hem-ultra-filtration:To separate aqueous To separate aqueous

phase of blood phase of blood from cellular and from cellular and proteinaceous proteinaceous componentcomponent…….. .. Increase HT Increase HT without transfusionwithout transfusion

AgainAgain

Initiation of CPBInitiation of CPB

UNCOMPLICATED INITIATIONUNCOMPLICATED INITIATION::TIME of initiation:TIME of initiation:

Cannulas placed and securedCannulas placed and secured ACT is acceptibleACT is acceptible Perfusionist is readyPerfusionist is ready

TECHNIQUE of initiation:TECHNIQUE of initiation: Venous clamps gradually removed to allow Venous clamps gradually removed to allow

venous return to bypassvenous return to bypass Arterial clamps removed to increase forward Arterial clamps removed to increase forward

flow with the start of main pumpflow with the start of main pump Monitoring of Monitoring of VR TO RESERVOIRVR TO RESERVOIR is highly is highly

important important


PRECAUTIONS:PRECAUTIONS:IF VENOUS RETURN IS POOR:IF VENOUS RETURN IS POOR:• Check cannulas for proper placement, kinks, Check cannulas for proper placement, kinks,

airlockairlock

• The pump flow should be slowed until the The pump flow should be slowed until the problem is resolvedproblem is resolved

• Adding volume may be needed ( transient)Adding volume may be needed ( transient)

Search for evidence of SVC obstructionSearch for evidence of SVC obstruction High CVPHigh CVP Facial engorgementFacial engorgement


PRECAUTIONS:PRECAUTIONS:With full CPB , the heart should With full CPB , the heart should emptyempty

Progressive distension may be due to Progressive distension may be due to • Malpositioning of venous cannulasMalpositioning of venous cannulas• AR needing immediate AXC AND AR needing immediate AXC AND

INTRODUCTION OF CARDIOPLEGIAINTRODUCTION OF CARDIOPLEGIA


After establishment of full flow with After establishment of full flow with appropriate VR, the following tasks will be appropriate VR, the following tasks will be checked within 5 minutes from the start of checked within 5 minutes from the start of CPB:CPB:

Assess arterial inflowAssess arterial inflowIf arterial blood is oxygenatedIf arterial blood is oxygenated

Is the flow direction is appropriateIs the flow direction is appropriate

Evidence of arterial dissection(persistent low MAP IN Evidence of arterial dissection(persistent low MAP IN PRESENCE of high inflow line pressure and falling of PRESENCE of high inflow line pressure and falling of reservoir level)reservoir level)


Assess venous outflowAssess venous outflow Is bypass completeIs bypass complete : :

Appropriate flowAppropriate flowAppropriate MAPAppropriate MAPAdequate VRAdequate VREmpty heart with CVP 2-5 cm H2O Empty heart with CVP 2-5 cm H2O

DISCONTINUE DRUG AND FLUID DISCONTINUE DRUG AND FLUID ADMINISTRATIONADMINISTRATION

Discontinue ventilation and inhalation Discontinue ventilation and inhalation drugs to the pt lungdrugs to the pt lung

Hypotension with onset of Hypotension with onset of bypassbypass

MAP between 30-40 mmHg is common MAP between 30-40 mmHg is common with the onset of CPBwith the onset of CPB

IMPROVE with hypothermic VC and IMPROVE with hypothermic VC and release OF catecholamines release OF catecholamines

Rarely needing vasopressorsRarely needing vasopressorsFor risk of cerebral and myocardial For risk of cerebral and myocardial

ischemia , MAP should be maintained ischemia , MAP should be maintained 60-80 mmHg if AXC is delayed 60-80 mmHg if AXC is delayed especially in pts with coronary especially in pts with coronary stenosis or ventricular hypertrophy stenosis or ventricular hypertrophy

Now on CPBNow on CPB

SYSTEMIC COOLING IS SYSTEMIC COOLING IS STARTEDSTARTED

Empty beating heart is Empty beating heart is going to fibrillatinggoing to fibrillating

Now AXC is applied Now AXC is applied (( beginning of coronary beginning of coronary ischemic time) ischemic time)

Cardioplegia is going on in Cardioplegia is going on in full speed to achieve full speed to achieve total suppression of total suppression of electrical and electrical and mechanical activity in mechanical activity in the heartthe heart

cardioplegiacardioplegia

perfusion.wmv

Management of CPBManagement of CPB

PUMP FLOW and MEAN ARTERIAL PUMP FLOW and MEAN ARTERIAL PRESSURE:PRESSURE:

A.A.Pump blood flow :Pump blood flow :• It should be more than 70% of COIt should be more than 70% of CO• Adequate value at normal temperature is Adequate value at normal temperature is

2.2 2.2 –– 3.1 L/ min/ m2 of body surface area 3.1 L/ min/ m2 of body surface area • With hypothermia, the pump flow can be With hypothermia, the pump flow can be

reduced reduced • At profound hypothermia, total At profound hypothermia, total

circulatory arrest for 60 circulatory arrest for 60 –– 90 min is 90 min is tolerabletolerable


PUMP FLOW and MEAN PUMP FLOW and MEAN ARTERIAL PRESSURE:ARTERIAL PRESSURE:

A.A.Pump blood flow :Pump blood flow :• Hem dilution decrease DO2 that need Hem dilution decrease DO2 that need

the increase of pump flowthe increase of pump flow

• Clinically both hypothermia and hem Clinically both hypothermia and hem dilution are applied at the same time dilution are applied at the same time so adjustment occurs at the same so adjustment occurs at the same time time


PUMP FLOW and MEAN ARTERIAL PUMP FLOW and MEAN ARTERIAL PRESSURE:PRESSURE:

B.B. MAP:MAP:MAP= PUMP FLOW X SVR MAP= PUMP FLOW X SVR Accepted value is 50 Accepted value is 50 –– 80 mmHg at 80 mmHg at

hypothermia hypothermia Hypotension commonly occurs with the Hypotension commonly occurs with the

onset of bypassonset of bypassDuring deep hypothermia 20-25 o C MAP During deep hypothermia 20-25 o C MAP

of 30mmHg is considered adequateof 30mmHg is considered adequate


B.B. MAP:MAP:• Persistent excessive decrease in MAP Persistent excessive decrease in MAP

(less than 30 mmHg):(less than 30 mmHg):1.1. Search for cause eg. Transducer error or Search for cause eg. Transducer error or

aortic dissectionaortic dissection2.2. Increase the pump flow rateIncrease the pump flow rate3.3. VasopressorsVasopressors

• High MAP ( more than 100 mmHg)High MAP ( more than 100 mmHg)1.1. Increase the anesthetic depthIncrease the anesthetic depth2.2. Decrease pump flow with cautionDecrease pump flow with caution3.3. Vasodilators Vasodilators


Monitoring during CPBMonitoring during CPB::BEDSIDE THE PREVIOUS MONITORSBEDSIDE THE PREVIOUS MONITORS

1.1. CVP and PAPCVP and PAP2.2. UOPUOP

ADDITIONALLYADDITIONALLY1.1. The pump flow rate adequacyThe pump flow rate adequacy2.2. Venous reservoir levelVenous reservoir level3.3. An arterial inflow line pressure (must An arterial inflow line pressure (must

remain below 300mmHg )remain below 300mmHg )4.4. Blood perfusate and venous drainageBlood perfusate and venous drainage


Monitoring during CPB:Monitoring during CPB:5.5. Myocardial temperatureMyocardial temperature

6.6. Inline O2 saturationInline O2 saturation

7.7. Inline pH ,CO2 and O2 tensionInline pH ,CO2 and O2 tension

Inadequate perfusion is suspected ifInadequate perfusion is suspected if• Low venous O2 tension (less than 40 Low venous O2 tension (less than 40

mmHg)mmHg)• Low venous O2 sat (less than 70%)Low venous O2 sat (less than 70%)• Progressive metabolic acidosisProgressive metabolic acidosis• Low UOPLow UOP


Monitoring during CPB:Monitoring during CPB:8.8. Serial ACT and extra heparin is Serial ACT and extra heparin is

given if ACT is less than 480 sec.given if ACT is less than 480 sec.

9.9. Serial Na, K, CaSerial Na, K, Ca

10.10. serial S. glucose (kept below 250 serial S. glucose (kept below 250 mg/dl)mg/dl)

11.11.Serial hematocrit: 20 -25%Serial hematocrit: 20 -25%


Myocardial preservationMyocardial preservation

Ventilation of the lungsVentilation of the lungs::Ventilation is stopped on establishment of Ventilation is stopped on establishment of

full adequate bypass full adequate bypass (heart stops to eject (heart stops to eject blood)blood)

Low flow O2 (1 -2 L ) may be benficial Low flow O2 (1 -2 L ) may be benficial during CPBduring CPB

Ventilation is resumed after the beginning Ventilation is resumed after the beginning of ventricular ejection after aortic of ventricular ejection after aortic declamp declamp


Management of respiratory gases:Management of respiratory gases:• Alpha stat (temperature uncorrected) Alpha stat (temperature uncorrected)

strategystrategy

most commonmost common• PH stat (temperature corrected) strategyPH stat (temperature corrected) strategy

Adjustment of gas flow on the Adjustment of gas flow on the oxygenatoroxygenator

A mixture of O2/air is used and adjusted A mixture of O2/air is used and adjusted according to blood gasesaccording to blood gases


Fluid balance during CPB:Fluid balance during CPB:ALL IV lines are shutoffALL IV lines are shutoff

Intake :Intake :• Cardioplegic solutionCardioplegic solution

• Fluids and blood added to reservoir (HT 18 Fluids and blood added to reservoir (HT 18 –– 20%)20%)

• The decreased bl level in the reservoirThe decreased bl level in the reservoir

Output :Output :• UOPUOP

• Increased blood level in venous reservoir Increased blood level in venous reservoir


Anesthesia during CPB:Anesthesia during CPB:Additional doses of anesthesia and Additional doses of anesthesia and

MR are given on the start and MR are given on the start and rewarmingrewarming

Anesthetic requirements decrease Anesthetic requirements decrease with hypothermiawith hypothermia

Increase the incidence of awareness Increase the incidence of awareness is present during CPBis present during CPB


Cerebral Cerebral protectionprotection

Renal protectionRenal protection

CPBCPB

Now the surgical Now the surgical procedure is procedure is ending ending …………………………………………..

Let us wait to Let us wait to separateseparate

Any QuestionsAny Questions? ?

SUMMARYSUMMARY

• Basic components of CPB are venous Basic components of CPB are venous reservoir,pump, oxygenator , heat reservoir,pump, oxygenator , heat exchanger and arterial filterexchanger and arterial filter

• Initiation of CPB needs high degree of Initiation of CPB needs high degree of vigilance and organizationvigilance and organization

• Management of CPB IS a continuation Management of CPB IS a continuation of prebypass management with of prebypass management with special precautionsspecial precautions

cardiopulmonary bypass

Education

left ventricular

pump blood

pump flow

main pump

arterial pressure

arterial filter

venous return

primary fluid