1

Problems in Cardiopulmonary Problems in Cardiopulmonary Bypass Bypass

2

IntroductionIntroduction

Perfusion Incident frequencyIdentify possible problems during CPBOutline remedial action

3

Incident FrequencyIncident 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

4

Incident distributionIncident 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

5

Topics for Discussion Topics for Discussion

Mediation of Patient’s immune system response

Unusual syndromesOxygenator problemsEmbolic events Protocol for Gross Air

Embolism

6

Systemic Inflammatory Systemic Inflammatory responseresponse

Platelet adhesion, activation of Factor XII Cascade activation :

kallikrein kinin-bradykinin Fibrinolytic Complement - C3a + C5a

leucocyte activation

oxygen free radicals

7

Mediation of Inflammatory Mediation of Inflammatory response response

1. Biocompatible materials

•Albumin in priming fluid

•Heparin coating - ionic - benzalkonium heparin surface grafting -

covalent - Carmeda

•Endothelial-like surfaces - phosphorylcholine

trillium

8

9

10

11

Mediation of Inflammatory Mediation of Inflammatory responseresponse

2. Leucocyte depletion

3. Isolation of Cardiotomy suction

12

Anti-thrombin III deficiencyAnti-thrombin III deficiency

In the absence of adequate circulating AT-III, heparin has little or no effect retarding blood coagulation.

Congenital AT-III deficiencyAcute venous thrombosisDICLiver cirrhosis

13

AT III - Diagnosis & actionAT III - Diagnosis & action

ACT still low after Heparin bolusRepeat bolus ( 30 - 40mg / Kg )ACT still low – give 2 units FFPRecheck ACTOn bypass add further FFP as reqd

14

Microaggregates - Cold Microaggregates - Cold agglutininsagglutinins

gp1 : Immunoglobulin M class directed against erythrocyte I antigen – wide thermal range 4 to 32C

gp2 : narrow thermal range 0 - 10CClotting / grainy appearanceInterfere with cardioplegia distribution &

myocardial protection.

15

Cold agglutinins – Cold agglutinins – management strategymanagement strategy

Rewarm pat to 320CSwitch to warm blood cardioplegiaSample to haematology to determine

thermal amplitudePre-op plasmapheresis for patients with

known agglutinins will remove most of the serum antibodies.

16

Malignant HyperthermiaMalignant 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

17

M.H. - remedial actionM.H. - remedial action

Stop all volatile anaesthetic agentsFiO2 to meet metabolic demandAdminister Dantrolene sodium IV Correct acidosis + hyperkalaemiaUse IV and surface cooling to control tempGive mannitol + frusemide to maintain

urine output of at least 2ml/Kg/hr

18

Sickle Cell DiseaseSickle 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

19

Sickle Cell Disease – Sickle Cell Disease – management strategymanagement strategy

Disease :

Trait :

Divert venous blood to cell salvage / plasmapheresis to separate plasma and plateletsReplace with RBC, FFP, colloid + crystalloid

Keep O2 saturations highAvoid acidosisAvoid hypothermiaWarm blood cardioplegia

20

MethaemoglobinaemiaMethaemoglobinaemia

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 enzymesDrug reaction – e.g. nitroglycerine,

isosorbide dinitrate, sodium nitrate

21

Remedial ActionRemedial Action

Withdraw all possible causative agentsAdminister 1% methylene blue infusion

1 – 3mg/kg over 5 minDoses > 7mg/kg are toxic High dose Vitamin C and/or exchange

transfusion in severe cases

22

Oxygenator ProblemsOxygenator Problems

Physical attrition Gas exchange capabilityInadequate anticoagulation

Heparin resistanceAT III deficiencyAdministration of Protamine !

23

Sources of EmboliSources of Emboli

Particulate

• Oxygenator - Polypropylene / polycarbonate

• CPB circuit - PVC / silicone (spallation)

• Patient - plaque calcium platelet / fibrin aggregates lipid globules muscle / connective tissue fragments

24

Sources of EmboliSources of EmboliGaseous

• 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

25

Protection Against Embolic Protection Against Embolic Events ( 1 )Events ( 1 )

Particulate

0.5 micron Pre-bypass filter

40 micron Arterial line filter

120 micron cardiotomy reservoir filter

26

Protection Against Embolic Protection Against Embolic Events ( 2 )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

27

Gross Air Embolism Incident - Gross Air Embolism Incident - ProtocolProtocol

PerfusionSurgicalAnaestheticPost operative care

28

PerfusionPerfusion

Discontinue bypass – clamp art + ven linesIdentify origin of problemReprime CPB circuit & art cannulaRetrograde SVC perfusion 1-2 LPMReinstitute bypass - temp (22 – 30o C)

Systemic pressure FiO2 = 100%

Off bypass @ 34o C

29

SurgicalSurgical

Clamp & remove aortic cannulaCannulate SVC or connect to SVC cannulaRetrieve blood/air exiting aorta via ventWhen no more air is visible at aortotomy

-- Re-cannulate aorta – reinstitute bypassBleed air from coronary arteriesComplete Surgical procedure

30

AnaestheticAnaesthetic

Place patient in steep Trendelenberg positionCompress carotid arteriesConsider administering :

Steroids Mannitol Antiplatelet agents

31

Post Bypass ManagementPost Bypass Management

Ventilate patient on 100% oxygenInstitute slight hyperventilationRewarm to normothermia over 24hrsPlace patient in reverse trendelenberg posn

Avoid hyperglycaemia + hyponatraemiaConsider Hyperbaric oxygen treatment

32