Problems in Cardiopulmonary Bypass

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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 Incidence / accidents Permanent injury/death
1980 Stoney US 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 / 130 1 / 1400
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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 air embolism
DIC
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Topics for Discussion

• Mediation of Patients 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 -
  benzalkonium heparin
• surface grafting -
• covalent -
  Carmeda
• Endothelial-like surfaces -
  phosphorylcholine
• trillium

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Mediation of Inflammatory response

• 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 42C 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 _at_ ? 85 O2 sat
• Trait Pats with ?45 Haemoglobin S
  cells will sickle _at_ ? 40 O2 sat

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Sickle Cell Disease management strategy

• Disease
• Trait

Divert venous blood to cell salvage /
plasmapheresis to separate plasma and
platelets Replace with RBC, FFP, colloid
crystalloid
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 gt 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 _at_ 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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