Embolic problems in cardiac surgery cpb view point
This presentation is the property of its rightful owner.
Sponsored Links
1 / 34

Embolic problems in Cardiac Surgery - CPB view point PowerPoint PPT Presentation


  • 61 Views
  • Uploaded on
  • Presentation posted in: General

Embolic problems in Cardiac Surgery - CPB view point. 인제대 일산 백병원 장우익. Embolic problems during cardiopulmonary bypass. Systemic embolism affecting the brain Both from CPB and underlying cardiovascular disease of the patients Central nervous dysfunction Major stroke - > macroembolism

Download Presentation

Embolic problems in Cardiac Surgery - CPB view point

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript


Embolic problems in cardiac surgery cpb view point

Embolic problems in Cardiac Surgery- CPB view point

인제대 일산 백병원

장우익


Embolic problems during cardiopulmonary bypass

Embolic problems during cardiopulmonary bypass

  • Systemic embolism affecting the brain

  • Both from CPB and underlying cardiovascular disease of the patients

  • Central nervous dysfunction

    • Major stroke - > macroembolism

    • Neuropsychologic problems -> microembolism


Interventions to reduce embolism

Interventions to reduce embolism

  • Surgical technique

    • Avoidance of major embolism of air, intracardiac thrombus, and calcific debris from diseased heart valves.

    • Avoidance of atheroembolism from the ascending aorta

  • CPB

    • Membrane oxygenators better than bubble oxygenators

    • Arterial line filter

    • Hemocompatible circuits

  • The most important embolic hazard of cardiac surgery is atheroembolism from manipulation of the ascending aorta


Macroemboli microemboli

Macroemboli & Microemboli

  • Macroemboli ; occluding flow >200um artery -> single macroembolus might result hemiplegia

  • Microemboli ; smaller arteries, arterioles, and capillaries. Single microembolus, no clinical effect. Numerous emboli can result diffuse pattern of CNS injury

  • Except perfusion accidents, macroemboli are unlikely to rise from the extracorporeal circuits, but rather from heart and aorta


Type of emboli and tissue effects

Type of emboli and tissue effects

  • Gas bubbles

    • Air, anesthetic gas(esp, nitrous oxide)

    • Dynamic equilibrium with the same gas dissolved in the plasma

    • Grow or shrink, dependent on temperature.

    • Small bubbles collapse when less than 10um

  • Biologic aggregates

    • Thrombus, platelet aggregates, fat

  • Inorganic debris

    • Fragment of polyvinyl chloride tubing, silicone antifoam, reduced currently.


Mechanism of microbubble tissue damage

Mechanism of microbubble tissue damage

  • Mechanical – compression against vessel wall, gap formation, fluid leakage, muscle hypertrophy

  • Inflammatory – neutrophil sequestration around bubble, increased permeability, radical species production, clot deposition

  • Complement – increased levels of C3a and C5a triggering PMNs, histamine release, prostaglandins, leukotriene synthesis

  • Clotting activation – platelet aggregation, thrombin production, thrombus generation


Entrapment of air into the arterial circulation

Entrapment of air into the arterial circulation

  • Events at the bypass machine

    • Not properly de-aired prior to bypass

    • Inattention to the reservoir level

    • Ruptured arterial pump-head tubing

    • Arterial line separation

    • Unnoticed rotation of the arterial pump head

    • Runaway pump head

    • Reversal of pump-head rotation

    • Reversal of tubing connected to the ventricular vent

    • Inadvertent detachment of oxygenator during CPB

    • Air transmitted through the membrane oxygenator by an occluded scavenger line

    • Clotted oxygenator

    • Pressurized cardiotomy reservoir


Entrapment of air into the arterial circulation1

Entrapment of air into the arterial circulation

  • Events on the operative field

    • Unexpected resumption of heartbeat

    • Opening of beating heart

    • Aortic root air during cardioplegic solution administration

    • Aortic root air accumulation secondary to suction for returning retrograde cardioplegic solution

    • Inadequate de-airing after cardiotomy

    • High flow suction deep in pulmonary artery

    • Use of an intraaortic blood pump while aorta is open

    • Rupture of pulsatile assist device

    • Difficult insertion of a vent line


Embolic problems in cardiac surgery cpb view point

Perfusion safety survey - trend


Increase in the safety of pefusion

Increase in the safety of pefusion

  • Increased use of safety devices

    • Arterial line filter, air bubble detectors, activated clotting time devices, one-way vent valves

  • Blood level sensors

  • One-way vent valves

  • Prebypass checklists, written protocols

  • Membrane oxygenators – downstream from the systemic pump, another device to trap/delay passage of air emboli

  • Centrifugal pump – added safety, deprime and prevent transmission of massive air embolism

    • Backflow from aorta, recommended use of a one-way flow valve in the arterial line


Adverse neurologic outcomes

Adverse neurologic outcomes

  • Vary widely, due to multiple other factors, such as cerebral blood flow, systemic inflammation, patient co-morbidities

  • Cognitive decline, such as memory deterioration ; 60% one week, 25-30% from 2 months to one year postop.


Relationship btw microembolism and adverse neurologic outcomes

Relationship btw microembolism and adverse neurologic outcomes

  • Higher incidence of poor neurologic functions.

  • Pugsley et al

    • Compared 50 pts bubble oxygenators with and without arterial filter

    • TCD monitor

    • More microemboli, more neuropsychologic deficts at 8days and 8weeks in unfiltered group


Microembolism and neurocognitive functions

Microembolism and neurocognitive functions

  • Comparisons between OPCAG and on-pump CABG

    • Slight tendency toward decreased performance in neurocognitive tests in the on-pump group. Decreased as the time after surgery increased.

  • Comparisons between valve and CABG

    • Increased rate of emboli in valve surgery

    • But no significant difference in neurocognitive test scores


Embolic problems in cardiac surgery cpb view point

Microembolism and

neurocognitive functions

  • Barbut et al 1997

  • 82 pt CABG, TCD in MCA

  • With stroke (4 pts) 449 emboli

  • Without stroke (78 pts) 169 emboli

  • Increased emboli results increased hospital stay


Microembolism and neurocognitive functions1

Microembolism and neurocognitive functions

  • Clark et al

  • 117 CABG pt

  • >60 emboli rate of neurologic dysfunction 35%

  • 30-59 emboli 4.2%

  • <30 emboli 2.4%


Detection and quantification of microembolism ultrasound

Detection and quantification of microembolism -ultrasound

  • Doppler mode – transcranial doppler

  • Limitations

    • Counts ; signals depends on software programming

    • Unclear whether increase in signal amplitude reflects increase in number of size of emboli

    • Quantification error ; attenuation of the signal by blood component on the surface, scattering of signals from clusters of bubbles, shielding of bubbles by others


Microemboli detection

Microemboli detection

  • Arterial filter is not 100% effective in blocking microemboli (even larger emboli)

  • Riley et al

    • 10 adult arterial line filter

    • Small pore size filter generally are more effective

    • 60-94% efficient in the removal of emboli in the 20-25 um range


Perfusionist interventions

Perfusionist interventions

  • Borger et al

  • 34 pts

  • 75% of all emboli detected during perfusionist interventions (drug injection and blood sampling)

  • Emboli count more higher during perfusion intervention (6.9/min) than during surgical intervention(1.5/min) or during baseline(0.4/min)


Perfusionist interventions1

Perfusionist interventions

  • Rodriquez et al

  • Emboli detected in MCA

  • 534 perfusionist interventions in 90 pts

  • Blood sampling and bolus injection higher than infusion

  • Repetitive purging of the syringe increase counts

  • Reservoir volume less than 800mL increased counts during blood sampling


Gaseous microemboli

Gaseous microemboli

  • Perfusion intervention ; during drug injection into the venous reservoir.

    • Air in the syringe, source of microemboli

  • Venous line air ; traversed membrane oxygenator and arterial line filter, possibly d/t bubble deformation or coalescence within or after the filter.


Vacuum assisted venous drainage

Vacuum assisted venous drainage

  • Augment drainage of venous blood

  • Smaller venous cannulae

  • Favor formation of gaseous microemboli

  • > -40 mmHg and high blood flow(6 L/min) ; increased GME


Embolic problems in cardiac surgery cpb view point

CO2

  • CO2 flooding of the op site

    • High solubility compared to room air

    • Disadvantage ; hypercarbia and respiratory acidosis

    • CO2 flooding only during the period of de-airing of the heart

  • CO2 potent cerebral vasodilator

    • Hypocapnia (PaCO2 30-32mmHg) ; reduce cerebral blood flow and embolization

    • No significant difference btw hypocarbic gr and normocarbic gr

    • Potential disadvantage of cerebral hypoperfusion


Steep trendelenburg position

Steep trendelenburg position

  • Rationale ; buoyancy effects will cause bubbles to rise and minimize cerebral embolization

  • Study ; did not decrease the cerebral embolic load

  • GME in flowing blood ejected from the heart respond more as an emulsion not subject to normal buoyancy effects as would be larger bubbles


Dynamic bubble trap

Dynamic bubble trap

  • Rotating stream that forced GME to the center of the flow -> passively vented out to the reservoir by a small tube located midstream and near the exit of the bubble trap.

  • Volume diverted 400-450mL/min

  • Reduction in the number of bubbles detected in the range 11-40um in MCA

  • Greater efficiency of removal by the bubble trap for the larger-sized GME ( >96% for bubbles >31um)


Dynamic bubble trap1

Dynamic bubble trap


Oxygenators capability of trapping air

Oxygenators – capability of trapping air

  • Oxygenator design that provided for rapid blood contact with the membrane material, increased bubble/membrane contact time, avoidance of high blood flow velocities and low pressure drop, and membrane bundle geometry all favored entrapment of GME

  • Capability of CPB circuits to remove entrained venous air.

    • Five type oxygenators

    • Air detected after arterial filter in all

    • Statistical different results among different manufactures

    • Contributing factors ; Residence time for blood and bubbles within the membrane oxygenator, pressure drop, turbulence in the flowing blood

    • Avoidance of venous air whenever it is observed.


Cannula type or excessive blood flow velocities

Cannula type or excessive blood flow velocities

  • ? Increased number of microemboli

  • High blood velocity could contribute to particulate release fron the aortic wall

  • Theoretically possible for GME to be produced by high blood flow velocities or abrupt pressure differences at cannula tips

  • Banaroia et al ;

    • 32 elective CABG pt

    • No correlation between blood velocities or type of cannula and the presence of TCD-detected emboli

    • Conventional cannula under conventional CPB, systemic flow was not important.


Newer circuits

Newer circuits

  • Minimizing prime volumes

  • Reducing reservoir volumes -> lessen perfusionist reaction time in the events

  • Without venous reservoir

  • CPB tubing smaller and shorter ->increased blood flow velocities thru the circuit.

  • Blood transit time is reduced -> decreased opportunity for GME to be removed prior to its return to the patients


Deairing of the venous drainage reduction of arterial microbubbles

Deairing of the venous drainage-reduction of arterial microbubbles

  • Deairing ; double clamp and saline filling

  • Connecting venous line without deairing of the venous line ; incorporation of 15cc air into the circuit

  • Entrapped air in the venous line is microfragmented while passing through the ECC with subsequent microbubble formation

  • Microbubbles detected after arterial filter ; once saturated they release captured gas bubbles.


Deairing of the venous drainage reduction of arterial microbubbles1

Deairing of the venous drainage-reduction of arterial microbubbles


Gross air bubbles massive air embolism

Gross air bubbles - Massive air embolism

  • Accident that can occur during cardiac surgery

  • Almost eliminated

    • 1/2500 in 1970s, 1/30000 in 1990s

  • Fatal / Permanent neurologic defect

  • Air bubble detectors, reservoir blood level sensors, arterial line filter, prebypass checklists


Cause

Cause

  • Sudden reduction in the blood level in the venous reservoir that is not noticed by the perfusionist

  • Inadvertent pressurization of the reservoir.

  • Air from the cardiac chamber

  • Runaway pump head

  • Inversion of left-sided heart vent

  • Reversal of pump head

  • Inadvertent detachment of oxygenator during bypass

  • Cardiotomy suction wedged deep into the pulmonary artery


Treatment

Treatment

  • Stop the circulation

  • Steep trendelenburg position

  • De-air the entire pump line

  • Retrograde SVC perfusion

  • Hypothermia

  • Barbiturate and corticosteroid

  • Hyperbaric oxygen therapy


Conclusion embolic problems during cardiopulmonary bypass

Conclusion Embolic problems during cardiopulmonary bypass

  • Brain most susceptible.

  • Cause of stroke is mostly from underlying disease.

  • Especially from atherosclerosis of the aorta.

  • Current CPB circuits itself – low embolic risk

  • Microembolism

    • Clinical effect ; difficult to notice but has potential risk

    • Efforts to reduce it!!

  • Gross air – rare incidence but fatal

    • Prevention !!!

    • Prebypass checklist, education, drill

    • Rapid reaction if occurs


  • Login