Download Problems in CPB

Problems in Cardiopulmonary
Bypass
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Introduction

Perfusion Incident frequency
 Identify possible problems during CPB
 Outline remedial action
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Incident Frequency
Date
Author
Country
1980 Stoney
US
Incidence / Permanent
accidents
injury/death
1 / 300
1 / 1000
1981 Wheeldon
UK
1 / 300
1 / 1500
1986 Kuruz
US
1 / 100
1 / 1000
1997 Jenkins
Australia 1 / 35
1 / 1300
2000 Mejak
US
1 / 1400
1 / 130
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Incident distribution
Stoney
Wheeldon
Kuruz
Jenkins
Mejak
DIC
Elec failure
Protamine
reaction
Heater/cooler
problems
DIC
air embolism
air embolism
Oxy failure
air embolism
Protamine
reaction
Elec failure
Oxy failure
Elec / mech
failure
Protamine
reaction/prob
Ao dissection /
cannula prob
Mech failure
Mech failure
Drug error
Oxy failure
Oxy failure
Oxy failure
DIC
air embolism
DIC
air embolism
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Topics for Discussion
Mediation of Patient’s immune system
response
 Unusual syndromes
 Oxygenator problems
 Embolic events  Protocol for Gross Air
Embolism

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Systemic Inflammatory
response

Platelet adhesion, activation of Factor XII

Cascade activation :




kallikrein
kinin-bradykinin
Fibrinolytic
Complement -  C3a + C5a
leucocyte activation
 oxygen free radicals
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Mediation of Inflammatory
response
1. Biocompatible materials
•Albumin in priming fluid
•Heparin coating - ionic
surface grafting covalent -
benzalkonium heparin
•Endothelial-like surfaces
phosphorylcholine
trillium
-
Carmeda
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Mediation of Inflammatory
response
2. Leucocyte depletion
3. Isolation of Cardiotomy suction
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Anti-thrombin III deficiency

In the absence of adequate circulating
AT-III heparin has little or no effect
retarding blood coagulation.
 Congenital AT-III deficiency
 Acute venous thrombosis
 DIC
 Liver cirrhosis
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AT III - Diagnosis & action

ACT still low after Heparin bolus
 Repeat bolus ( 30 - 40mg / Kg )
 ACT still low – give 2 units FFP
 Recheck ACT
 On bypass add further FFP as reqd
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Microaggregates - Cold
agglutinins

gp1 : Immunoglobulin M class directed
against erythrocyte I antigen – wide thermal
range 4 to 32C
 gp2 : narrow thermal range 0 - 10C
 Clotting / grainy appearance
 Interfere with cardioplegia distribution &
 myocardial protection.
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Cold agglutinins –
management strategy
Rewarm pat to 320C
 Switch to warm blood cardioplegia
 Sample to haematology to determine
thermal amplitude
 Pre-op plasmapheresis for patients with
known agglutinins will remove most of the
serum antibodies.

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Malignant Hyperthermia
Inherited disorder – rapid temp to 42°C in
response to volatile anaesthetic agents
 Abnormal calcium metabolism myoplasmic ionic calcium
 Metabolic rate, resp + met acidosis, K+ ,
 lactate + pyruvate, tachycardia,  temp
 Massive muscle swelling, Pul oedema, DIC
& acute renal failure   70% mortality

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M.H. - remedial action

Stop all volatile anaesthetic agents
 FiO2 to meet metabolic demand
 Administer Dantrolene sodium IV
 Correct acidosis + hyperkalaemia
 Use IV and surface cooling to control temp
 Give mannitol + frusemide to maintain
urine output of at least 2ml/Kg/hr
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Sickle Cell Disease

Low O2 sat +/- hypothermia will cause
sickle cells to clump + precipitate
 Disease : Pats with 50% Haemoglobin S
cells will sickle @  85% O2 sat
 Trait :
Pats with 45% Haemoglobin S
cells will sickle @  40% O2 sat
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Sickle Cell Disease –
management strategy

Disease :
Divert venous blood to cell salvage / plasmapheresis
to separate plasma and platelets
Replace with RBC, FFP, colloid + crystalloid

Trait :
Keep O2 saturations high
Avoid acidosis
Avoid hypothermia
Warm blood cardioplegia
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Methaemoglobinaemia

Severe cyanosis of arterial blood ( often
appears chocolate brown rather than blue )
in spite of high pO2
 Haem ion oxidised from ferrous (Fe 2+) to
ferric (Fe 3+) state
 Hereditary deficiency in control enzymes
 Drug reaction – e.g. nitroglycerine,
isosorbide dinitrate, sodium nitrate
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Remedial Action

Withdraw all possible causative agents
 Administer 1% methylene blue infusion
1 – 3mg/kg over 5 min
 Doses > 7mg/kg are toxic
 High dose Vitamin C and/or exchange
transfusion in severe cases
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Oxygenator Problems

Physical attrition
  Gas exchange capability
 Inadequate anticoagulation
Heparin resistance
AT III deficiency
Administration of Protamine !
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Sources of Emboli
Particulate
• Oxygenator
- Polypropylene / polycarbonate
• CPB circuit
- PVC / silicone (spallation)
• Patient
- plaque
calcium
platelet / fibrin aggregates
lipid globules
muscle / connective tissue fragments
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Sources of Emboli

Gaseous
• Cannulation
• Venous air entrainment – (VAVD?)
• Inadequate de-airing of the heart
• Inappropriate vent suction
• Centrifugal pump – retrograde flow
• IABP deflation during aortotomy
• Temperature Gradients
• Catastrophic gross air embolism
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Protection Against Embolic
Events ( 1 )

Particulate
0.5 micron Pre-bypass filter
40 micron Arterial line filter
120 micron cardiotomy reservoir filter
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Protection Against Embolic
Events ( 2 )

Gaseous
•Microemboli - arterial line filter + purge line
- elimination of entrained venous air
- vent line – one-way pressure relief valves
•Macroemboli -
oxygenator resevoir level sensor
arterial line filter + purge line
ultrasonic bubble detector in art line
anti-siphon valve / software for
centrifugal pumps
- CO2 insufflation
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Gross Air Embolism Incident Protocol

Perfusion
 Surgical
 Anaesthetic
 Post operative care
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Perfusion
Discontinue bypass – clamp art + ven lines
 Identify origin of problem
 Reprime CPB circuit & art cannula
 Retrograde SVC perfusion 1-2 LPM
 Reinstitute bypass -  temp (22 – 30o C)
Systemic pressure
FiO2 = 100%
 Off bypass @ 34o C

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Surgical

Clamp & remove aortic cannula
 Cannulate SVC or connect to SVC cannula
 Retrieve blood/air exiting aorta via vent
 When no more air is visible at aortotomy
-- Re-cannulate aorta – reinstitute bypass
 Bleed air from coronary arteries
 Complete Surgical procedure
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Anaesthetic

Place patient in steep Trendelenberg position
 Compress carotid arteries
 Consider administering :



Steroids
Mannitol
Antiplatelet agents
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Post Bypass Management

Ventilate patient on 100% oxygen
 Institute slight hyperventilation
 Rewarm to normothermia over 24hrs
 Place patient in reverse trendelenberg posn
 Avoid hyperglycaemia + hyponatraemia
 Consider Hyperbaric oxygen treatment
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