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EMERGENCY OXYGENATOR CHANGEOUT Predisposing Factors and Resulting Incidence Tony Fisher Harefield Hospital U.K.

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Presentation on theme: "EMERGENCY OXYGENATOR CHANGEOUT Predisposing Factors and Resulting Incidence Tony Fisher Harefield Hospital U.K."— Presentation transcript:

1 EMERGENCY OXYGENATOR CHANGEOUT Predisposing Factors and Resulting Incidence Tony Fisher Harefield Hospital U.K.

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3 OXYGENATOR PROBLEMS Leaks in; –Membranes –Housing –Heat Exchanger Grossly contaminated circuit Clots in Oxygenator / Reservoir Oxygenator Failure Raised trans - oxygenator pressure

4 LEAKING OXYGENATORS INCIDENCE StoneyI in 23,426 cases Kurusz 2,371 Jenkins 1,932 Fisher 20,781 Housing leaks resulting in EOC Stensved 1,635 Mejak 37,294 Water to blood leaks

5 CONTAMINATED OXYGENATORS INCIDENCE Stoney1 in 374,819 cases Kurusz 3,260 Jenkins 6,762 Mejak 23,148

6 CLOTS IN OXYGENATOR and D.I.C. INCIDENCE Stoney in 787 cases Wheeldon ,667 Kurusz1986 1,479 Svenmarker Jenkins1997 3,005 Mejak2000 2,283

7 CLOTS IN OXYGENATOR n= 68,937 97,313 Oxy clotted going back on bypass + aprotinin 6 0 Oxy clotted going back on bypass 01 Oxy clotted + aprotinin 31 Oxy clotted 12

8 FAILED OXYGENATORS INCIDENCE Stoney1 in 3,022 cases Wheeldon 2,063 Kurusz 1,134 Mejak 2,458

9 POSSIBLE CAUSES OF FAILED MEMBRANE OXYGENATORS Clot formation Plasma or blood leak Raised trans-oxygenator pressure gradient (R.T.P.)

10 CONTRIBUTING FACTORS FOR FAILED OXYGENATORS Gas supply problems Metabolic requirements –State of anaesthesia, Poor oxygenator design Large patients + + +

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12 CHARACTERISTICS OF R.T.P. GRADIENT A.C.T. is greater than 480 secs Starts to occur immediately upon going on bypass Pressure drop across oxygenator increases rapidly Reaches a plateau Reduces rapidly back to base line after about 30 minutes or on rewarming

13 CHARACTERISTICS OF R.T.P. GRADIENT Effect may be reduced by rewarming Oxygenation may become inadequate If the oxygenator is changed out it does not recur

14 SUGGESTED CAUSES OF RAISED T.O.P. GRADIENT The blockage is caused by the development of a fibrin - platelet thrombus This appears to start in the heat exchanger but grows into, or breaks away into the oxygenator fibre bundle

15 RAISED TRANS-OXYGENATOR PRESSURE GRADIENT INCIDENCE Study Incidence Requiring Size E.O.C. Stensved 11,451 1 in 89 1 in 954 Blomback 1, Wahba 1, Fisher 3, ,228

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17 MEASUREMENT of TRANS- OXYGENATOR PRESSURE Reasonably linear relationship between Pressure Gradient and Flow Therefore can be based on Poiseuille’s Formula Flow =  x p x r 4 8 x  x l

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19 MEASUREMENT of TRANS- OXYGENATOR PRESSURE Variations in measurements due to; Viscosity changes –Haematocrit –Prime constituents –Flow –Temperature Site of measurement OVERALL Variation about 10%

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27 INCIDENCE by HOSPITAL Hospital No. cases No incidents No. of cases per incidence

28 INCIDENCE by OXYGENATOR Oxygenator No. Used No.Incidents Terumo SX Terumo SX Medos Hilite2640 Affinity3410 Sorin Monolyth1282 Cobe Duo9868 Cobe Optima2080 Dideco Avant9821 Bard Quantum3714 Gish Vision 870

29 Raised Trans-Oxygenator Pressure Gradient can only be seen if it is monitored –Greater awareness of the problem results in more monitoring If monitoring is not done then the problem presents as a “Failed Oxygenator”

30 FAILED OXYGENATORS INCIDENCE YEAR Stoney1 in 3,022 cases1979 Wheeldon 2, Kurusz 1, Mejak 2,

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32 SUMMARY Happens immediately upon going on bypass Eventually disappears Does not recur upon emergency changeout Incidence varies between different units At least two different possibly unrelated initiating factors These factors may always have been present

33 CONCLUSION Oxygenators may need emergency replacing due to mechanical failures A rare event - maybe 1 in 20,000 cases This can only be improved by better quality control by the manufacturers

34 CONCLUSION Oxygenators may need emergency replacing due to clotting problems Incidence 1 in 3,000 cases This problem needs to be addressed by improving anticoagulation monitoring

35 CONCLUSION Oxygenators may need emergency replacing due to a fibrin - platelet thrombus which may be demonstrated by a raised trans-oxygenator pressure gradient. Incidence 1 in 1,000 cases This problem may always have been with us, and needs to be addressed by continuing research into its aetiology.


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