Routine cpb weaning

32
Routine weaning Routine weaning from from CPB CPB Abeer elnakera Abeer elnakera Lecturer of anesthesia Lecturer of anesthesia 2013 2013

Transcript of Routine cpb weaning

Page 1: Routine cpb weaning

Routine weaning from Routine weaning from CPBCPB

Abeer elnakeraAbeer elnakera

Lecturer of anesthesiaLecturer of anesthesia

20132013

Page 2: Routine cpb weaning

Objectives Objectives

To emphasize the role of To emphasize the role of Communications between surgeon, Communications between surgeon, anesthesiologist and perfusionist as a anesthesiologist and perfusionist as a corner stone for successful CPB corner stone for successful CPB separation (Isa)separation (Isa)

to discuss the steps of routine to discuss the steps of routine weaning from CPBweaning from CPB

To Demonstrate the high importance To Demonstrate the high importance of Meticulous monitoring and prompt of Meticulous monitoring and prompt interventionintervention

Page 3: Routine cpb weaning

As a roleAs a role

There should be close and clear There should be close and clear communication among the per communication among the per fusionist, the surgeon, and the fusionist, the surgeon, and the anesthesiologist while weaning a anesthesiologist while weaning a patient from CPBpatient from CPB

Page 4: Routine cpb weaning

The anesthesiologistThe anesthesiologist

Page 5: Routine cpb weaning

The actual process of weaning from The actual process of weaning from CPBCPB

begins with begins with partially occluding the venous partially occluding the venous return cannulareturn cannula with a clamp. This causes blood with a clamp. This causes blood to flow into the right ventricle. As the right to flow into the right ventricle. As the right ventricle fills and begins to pump blood through ventricle fills and begins to pump blood through the lungs, the lungs, the left side of the heart will begin the left side of the heart will begin to fillto fill. When this occurs, . When this occurs, the left ventricle the left ventricle will begin to ejectwill begin to eject, and the , and the arterial arterial waveform will become pulsatilewaveform will become pulsatile. Next, . Next, the perfusionist will gradually decrease the the perfusionist will gradually decrease the pump flow rate to avoid emptyingpump flow rate to avoid emptying the pump the pump reservoir..reservoir..

Page 6: Routine cpb weaning
Page 7: Routine cpb weaning

the per fusionist should the per fusionist should communicate to the physicianscommunicate to the physicians

three important parameters:three important parameters: the current flow rate of the pump, the current flow rate of the pump, the volume in the pump reservoir, the volume in the pump reservoir, and the oxygen saturation of venous and the oxygen saturation of venous

blood returning to the pump from the blood returning to the pump from the patient. patient.

Page 8: Routine cpb weaning

current flow rate of the pump

Stage of weaning

Page 9: Routine cpb weaning

the volume in the pump reservoir

how much blood is available for transfusion to fill the heart and lungs as CPB is discontinued.

If volume is less than 400-500More fluid volume must be addedTo the reservoir

Page 10: Routine cpb weaning

•the oxygen saturation of venous blood returning• to the pump from the patient.

If ˃ 60%

Adequate perfusion

If < 50%

If 50- 60%

Inadequateperfusion

MarginalImprove deliveryAnd decreaseconsumption

Followclosely

Page 11: Routine cpb weaning

As the patient is weaned from As the patient is weaned from CPBCPB

a rising svo2a rising svo2 suggests that the net flow suggests that the net flow to the body is increasing and that the to the body is increasing and that the heart and lungs will support the heart and lungs will support the circulation;circulation;

a falling svo2a falling svo2 indicates that tissue indicates that tissue perfusion is decreasing and that further perfusion is decreasing and that further intervention to improve cardiac intervention to improve cardiac performance will be needed before coming performance will be needed before coming off CPB off CPB

Page 12: Routine cpb weaning

One approach to weaning from One approach to weaning from CPBCPB

is to bring the is to bring the filling pressurefilling pressure being being monitored (e.g., central venous monitored (e.g., central venous pressure [CVP], PAOP, LAP) to a pressure [CVP], PAOP, LAP) to a specific, predetermined level specific, predetermined level somewhat lower than may be somewhat lower than may be necessary and then assess the necessary and then assess the hemdynamics. hemdynamics.

Page 13: Routine cpb weaning

Volume (preload) of the heart Volume (preload) of the heart may also be judged bymay also be judged by direct observation( RV)direct observation( RV) of its of its

size or with size or with TEE (LV)TEE (LV).. Further filling is done in Further filling is done in small increments (50 to 100 small increments (50 to 100

mL)mL) while closely monitoring the preload until thewhile closely monitoring the preload until the

hemodynamics appear satisfactory as hemodynamics appear satisfactory as judged by the judged by the arterial pressure, the arterial pressure, the appearance of the heart, and the appearance of the heart, and the trend of the svo2trend of the svo2 . .

Overfilling and distention of the heartOverfilling and distention of the heart should should be avoided because it may stretch the myofibrils beyond be avoided because it may stretch the myofibrils beyond the most efficient length and dilate the annuli of the mitral the most efficient length and dilate the annuli of the mitral and tricuspid valves, rendering them incompetent, which is and tricuspid valves, rendering them incompetent, which is easily detected with TEE. easily detected with TEE.

Page 14: Routine cpb weaning

NOW we are off bypassNOW we are off bypass . . When the pump flow has been When the pump flow has been

decreased to 1 L/min or less in an decreased to 1 L/min or less in an adult and the hemodynamics are adult and the hemodynamics are satisfactory (satisfactory (systolic arterial pressure systolic arterial pressure is judged to be adequate > 80–90 mm is judged to be adequate > 80–90 mm Hg), Hg), the venous cannula may be the venous cannula may be completely clamped and the pump completely clamped and the pump

flow turned offflow turned off. . At this point, At this point, the patient is “off the patient is “off bypass.” bypass.”

Page 15: Routine cpb weaning

This is a critical juncture in the This is a critical juncture in the operationoperation. .

The anesthesiologist should pause a The anesthesiologist should pause a moment to make a brief scan of the moment to make a brief scan of the patient and monitors to patient and monitors to confirm that confirm that – the lungs are being ventilated with the lungs are being ventilated with

oxygen, oxygen, – the hemodynamic status is acceptable the hemodynamic status is acceptable

and stable,and stable,– the electrocardiogram shows no new the electrocardiogram shows no new

signs of ischemia, signs of ischemia, – the heart does not appear to be the heart does not appear to be

distending, anddistending, and– the drug infusions are functioning as the drug infusions are functioning as

desired. desired.

Page 16: Routine cpb weaning

Next Next

Further fine-tuning of the Further fine-tuning of the preloadpreload is accomplished by is accomplished by transfusing 50- to 100-mL boluses transfusing 50- to 100-mL boluses from the pump reservoir through the from the pump reservoir through the arterial cannula and observing the arterial cannula and observing the effect on hemodynamics. effect on hemodynamics.

Most patients fall into one of Most patients fall into one of fourfour groups groups when coming off bypasswhen coming off bypass

Page 17: Routine cpb weaning

Group I: Group I: VigorousVigorous

Group II: Group II: HypovolHypovolemicemic

Group Group IIIA: LV IIIA: LV Pump Pump FailureFailure

Group Group IIIB: RV IIIB: RV Pump Pump FailureFailure

Group IV: Group IV: VasodilatVasodilated ed (Hyperdy(Hyperdynamic)namic)

Blood Blood pressurepressure

normalnormal LowLow LowLow LowLow LowLow

CVPCVP Normal Normal LowLow Normal Normal or or highhigh

HighHigh Normal Normal or or low low

PAPPAP normalnormal LowLow HighHigh Normal Normal or or highhigh

Normal Normal or or low low

PWPPWP normalnormal LowLow HighHigh Normal Normal or or lowlow

Normal Normal or or low low

COPCOP Normal Normal LowLow LowLow LowLow HighHigh

SVRSVR Normal Normal Normal Normal or or highhigh

HighHigh Normal Normal or or highhigh

LowLow

TTTTTT nonenone volumevolume Inotrope; Inotrope; reduce reduce afterload, afterload, IABP, LVADIABP, LVAD

Pulmonary Pulmonary vasodilatorvasodilator; RVAD; RVAD

Increase Increase hematocrithematocrit

Page 18: Routine cpb weaning

Hypovolemic patientsHypovolemic patients are a mixed group that includes both are a mixed group that includes both

patients with patients with normal ventricular function normal ventricular function and those with varying degrees of and those with varying degrees of impairmentimpairment. .

Those with preserved myocardial functionThose with preserved myocardial function quickly respond to 100-mL aliquots of pump quickly respond to 100-mL aliquots of pump blood infused via the aortic cannula. Blood blood infused via the aortic cannula. Blood pressure and cardiac output rise with each pressure and cardiac output rise with each bolus, and the increase becomes bolus, and the increase becomes progressively more sustained. Most of these progressively more sustained. Most of these patients maintain good blood pressure and patients maintain good blood pressure and cardiac output with a left ventricular filling cardiac output with a left ventricular filling pressure below 10–15 mm Hg. pressure below 10–15 mm Hg.

Page 19: Routine cpb weaning

Hypovolemic patientsHypovolemic patients

Ventricular impairmentVentricular impairment should be suspected in should be suspected in

hypovolemic patients whose hypovolemic patients whose filling pressures rise during filling pressures rise during volume infusion without volume infusion without appreciable changes in blood appreciable changes in blood pressure or cardiac output or in pressure or cardiac output or in those who require filling those who require filling pressures above 10–15 mm Hg. pressures above 10–15 mm Hg.

Page 20: Routine cpb weaning

Patients with pump failurePatients with pump failure If there is acute failure of the If there is acute failure of the

circulation as evidenced by unstable circulation as evidenced by unstable rhythm, falling arterial and rising rhythm, falling arterial and rising filling pressures, or visible distention filling pressures, or visible distention of the heart,of the heart,. .

In such cases, CPB is In such cases, CPB is reinstitutedreinstituted while while– inotropic therapy is initiated.inotropic therapy is initiated.– If SVR is high, afterload reduction with If SVR is high, afterload reduction with

nitroprusside or an inodilator (eg, nitroprusside or an inodilator (eg, milrinone) can be triedmilrinone) can be tried. .

Page 21: Routine cpb weaning

Patients with pump failurePatients with pump failure

The patient should be evaluated for The patient should be evaluated for unrecognized ischemia (kinked graft or unrecognized ischemia (kinked graft or coronary vasospasm), valvular coronary vasospasm), valvular dysfunction, shunting, or right dysfunction, shunting, or right ventricular failure (the distention is ventricular failure (the distention is primarily right sided). TEE may primarily right sided). TEE may facilitate the diagnosis in these cases.facilitate the diagnosis in these cases.

If inotropes and afterload reduction fail, If inotropes and afterload reduction fail, intraaortic balloon pump (IABP)intraaortic balloon pump (IABP) is is initiated before another attempt is made to initiated before another attempt is made to wean the patient. wean the patient.

Page 22: Routine cpb weaning

Patients with pump failurePatients with pump failure

Use of partial bypass, in the form of Use of partial bypass, in the form of a left or right ventricular assist a left or right ventricular assist devicedevice (LVAD or RVAD, (LVAD or RVAD, respectively), may be necessary for respectively), may be necessary for patients with refractory pump failure. patients with refractory pump failure.

Page 23: Routine cpb weaning

When stable again When stable again off bypassoff bypass

When the When the hemodynamics hemodynamics appear to be stable appear to be stable and adequate, the and adequate, the surgeon may surgeon may remove the remove the venous cannulavenous cannula from the heart. from the heart.

Page 24: Routine cpb weaning

The next stepThe next step is to is to transfuse as transfuse as

much as possible of much as possible of the blood remaining the blood remaining in the pump in the pump reservoir into the reservoir into the patient before patient before removal of the removal of the arterial cannulaarterial cannula. . This is usually easier This is usually easier and quicker than and quicker than transfusing through transfusing through the intravenous the intravenous infusions after infusions after decannulation. decannulation.

Page 25: Routine cpb weaning

Protamine Protamine

After discontinuing CPB, the After discontinuing CPB, the anticoagulation by heparin is anticoagulation by heparin is reversed with protaminereversed with protamine. Depending on . Depending on institutional preference, protamine may be institutional preference, protamine may be administered before or after removal of administered before or after removal of the arterial cannula.the arterial cannula.

Giving it before removal allows for Giving it before removal allows for continued transfusion from the pump continued transfusion from the pump and easier return to CPBand easier return to CPB if there is a if there is a severe protamine reaction severe protamine reaction

Page 26: Routine cpb weaning

When transfusion of the pump When transfusion of the pump reservoir blood is completedreservoir blood is completed

, , a thorough assessment of the a thorough assessment of the patient'spatient's condition should be made condition should be made before removing the arterial cannula, before removing the arterial cannula, because after this is done returning to CPB because after this is done returning to CPB becomes much more difficult. becomes much more difficult.

Hemodynamics should be satisfactory Hemodynamics should be satisfactory and stableand stable. (TEE is valuable). (TEE is valuable)

Adequate oxygenation and Adequate oxygenation and ventilation should be confirmedventilation should be confirmed

Page 27: Routine cpb weaning

When transfusion of the pump When transfusion of the pump reservoir blood is completed (cont.)reservoir blood is completed (cont.) Bleeding from the heart should be at Bleeding from the heart should be at

a manageable levela manageable level before removal of before removal of the arterial cannula. because it may be the arterial cannula. because it may be difficult to keep up with the blood loss difficult to keep up with the blood loss through intravenous infusions alone. through intravenous infusions alone.

Bleeding sites behind the heart may Bleeding sites behind the heart may have to be repaired on CPBhave to be repaired on CPB if the if the patient cannot tolerate lifting the heart to patient cannot tolerate lifting the heart to expose the problem area. expose the problem area.

Page 28: Routine cpb weaning

At the time of arterial At the time of arterial decannulationdecannulation,,

the systolic pressure should be the systolic pressure should be between 85 and 105 mmHg to between 85 and 105 mmHg to minimize the risk of dissection or minimize the risk of dissection or tearing of the aortatearing of the aorta. . The head of the The head of the bed may be raised, or small boluses bed may be raised, or small boluses of a short-acting vasodilatorof a short-acting vasodilator may be may be givengiven as necessaryas necessary..

Tight control of the arterial blood Tight control of the arterial blood pressure may be neededpressure may be needed for a few for a few minutes until the cannulation site is minutes until the cannulation site is secure.secure.

Page 29: Routine cpb weaning

Now the routine process of Now the routine process of discontinuing CPB is completediscontinuing CPB is complete

. However, . However, in patients with poor in patients with poor ventricular function after CPB, ventricular function after CPB, multiple drugs or even multiple drugs or even mechanical assist devices may mechanical assist devices may be required throughout the rest be required throughout the rest of the operation and continued of the operation and continued in the intensive care unit.in the intensive care unit.

Page 30: Routine cpb weaning

Any Questions ?Any Questions ?

Page 31: Routine cpb weaning

SummarySummary

Communications between Communications between anesthesiologist, surgeon and anesthesiologist, surgeon and perfusionist are highly usefulperfusionist are highly useful

The actual process of weaning from The actual process of weaning from CPBCPB

Patient categories after CPBPatient categories after CPB Continuous assessment and Continuous assessment and

stabilization of the patient continue stabilization of the patient continue all through the post bypass period all through the post bypass period

Page 32: Routine cpb weaning

Thank youThank you