Routine cpb weaning
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Transcript of Routine cpb weaning
Routine weaning from Routine weaning from CPBCPB
Abeer elnakeraAbeer elnakera
Lecturer of anesthesiaLecturer of anesthesia
20132013
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
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
The anesthesiologistThe anesthesiologist
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..
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.
current flow rate of the pump
Stage of 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
•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
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
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.
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.
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.”
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.
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
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
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.
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.
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. .
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.
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.
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.
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.
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
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
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.
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.
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.
Any Questions ?Any Questions ?
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
Thank youThank you