Transcript EMERGENCY OXYGENATOR CHANGEOUT

EMERGENCY OXYGENATOR
CHANGEOUT
Predisposing Factors and Resulting
Incidence
Tony Fisher
Harefield Hospital
U.K.
OXYGENATOR PROBLEMS
AUTHOR YEAR COUNTRY SIZE INCIDENCE CHANGEOUT
Per number of cases
Stoney
Wheeldon
Kurusz
Svenmarker
Jenkins
Fisher
Stensved
Mejak
1979
1981
1986
1991
1997
1997
1998
2000
U.S.A,
374,819
U.K.
33,000
U.S.A
573,785
Scandinavia 8,803
Australia 27,048
U.K.
166,250
Sweden
11,451
U.S.A.
671,290
2,536
2,062
536
149
211
70
1093
1,572
1,100
773
4,375
954
3,880
OXYGENATOR PROBLEMS
• Leaks in;
– Membranes
– Housing
– Heat Exchanger
•
•
•
•
Grossly contaminated circuit
Clots in Oxygenator / Reservoir
Oxygenator Failure
Raised trans - oxygenator pressure
LEAKING OXYGENATORS
Stoney
Kurusz
Jenkins
Fisher
INCIDENCE
I in 23,426 cases
2,371
1,932
20,781
Housing leaks resulting in
EOC
Stensved
Mejak
1,635
37,294
Water to blood leaks
CONTAMINATED OXYGENATORS
INCIDENCE
Stoney
Kurusz
Jenkins
Mejak
1 in 374,819 cases
3,260
6,762
23,148
CLOTS IN OXYGENATOR
and D.I.C.
INCIDENCE
Stoney
Wheeldon
Kurusz
Svenmarker
Jenkins
Mejak
1979
1981
1986
1991
1997
2000
1 in 787 cases
3,667
1,479
400
3,005
2,283
CLOTS IN OXYGENATOR
n=
Oxy clotted going
back on bypass
+ aprotinin
Oxy clotted going
back on bypass
Oxy clotted
+ aprotinin
Oxy clotted
1990 - 92
68,937
1994 - 96
97,313
6
0
0
1
3
1
1
2
FAILED OXYGENATORS
INCIDENCE
Stoney
Wheeldon
Kurusz
Mejak
1 in 3,022 cases
2,063
1,134
2,458
POSSIBLE CAUSES OF
FAILED MEMBRANE
OXYGENATORS
• Clot formation
• Plasma or blood leak
• Raised trans-oxygenator pressure gradient
(R.T.P.)
CONTRIBUTING FACTORS
FOR FAILED OXYGENATORS
• Gas supply problems
• Metabolic requirements
– State of anaesthesia, + + + +
• Poor oxygenator design
• Large patients
• +++
Oxygen Transferred versus Inspired
Oxygen Concentration
FiO2
1
0.8
HF5000
UNIVOX
0.6
0.4
0.2
75
175
275
375
Oxygen Transferred ml/min
475
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
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
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
RAISED TRANS-OXYGENATOR
PRESSURE GRADIENT
Stensved
Blomback
Wahba
Fisher
INCIDENCE
Study Incidence Requiring
Size
E.O.C.
11,451 1 in 89
1 in 954
1,800
164
600
1,959
42
490
3,684
228
1,228
Pressure gradient
(mm Hg)
Trans-Oxygenator Pressure Gradient
for Capiox SX25
200
150
100
50
0
0
2
4
Flow (L / min)
6
8
MEASUREMENT of TRANSOXYGENATOR PRESSURE
• Reasonably linear relationship between
Pressure Gradient and Flow
• Therefore can be based on Poiseuille’s
Formula
Flow =
 x p x r4
8 x  x l
mm Hg / L
Trans Oxygenator Pressure Gradient
per Litre Flow against Time
40
30
20
10
0
Cobe Duo
0 10 20 30 40 50 60 70 80 90
Time (mins)
Sorin
Monolyth
Pro
MEASUREMENT of TRANSOXYGENATOR PRESSURE
Variations in measurements due to;
• Viscosity changes
–
–
–
–
Haematocrit
Prime constituents
Flow
Temperature + + + +
• Site of measurement
• OVERALL Variation about 10%
RTP EVENT with TERUMO SX25
Pre s s . Grad. / l
40
30
20
10
0
0
20
40
60
80
100
Time (mins)
RTP EVENT with COBE DUO
Press Grad / l
80
60
40
20
0
0
10
20
30
40
50
60
Time (mins)
press grad / l
RTP EVENT with QUANTUM
100
80
60
40
20
0
0
15
30
45
60
75
Time (mins)
90
RTP EVENT with SORIN
MONOLYTH PRO
Press. Grad. / l
60
50
40
30
20
10
0
0
15
30
45
60
Time (mins)
RTP EVENT with COBE DUO
(1 Compartment)
Press Grad. / l
200
150
100
50
0
0
15
30
45
Time (mins)
Pre s s ure grad. / l
RTP EVENT with COBE DUO
80
60
40
20
0
0
20
40
60
80
100
Time (mins)
Press grad / l
RTP EVENT WITH BARD QUANTUM
and CHANGEOUT
100
80
60
40
20
0
0
10
20
30
40
50
60
Time (mins)
INCIDENCE by HOSPITAL
Hospital
1
No. cases
602
No incidents
No. of cases
per incidence
1
602
2
3
4
5
6
7
8
730
982
498
400
144
87
241
4
1
2
1
2
2
3
183
982
249
400
72
44
80
INCIDENCE by
OXYGENATOR
Oxygenator
No. Used
No.Incidents
Terumo SX18
Terumo SX25
Medos Hilite
Affinity
Sorin Monolyth
Cobe Duo
Cobe Optima
Dideco Avant
Bard Quantum
25
300
264
341
128
986
208
982
371
0
1
0
0
2
8
0
1
4
Gish Vision
87
0
• 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”
FAILED OXYGENATORS
INCIDENCE
Stoney
Wheeldon
Kurusz
Mejak
1 in 3,022 cases
2,063
1,134
2,458
YEAR
1979
1981
1986
2000
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
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
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
CONCLUSION
• Oxygenators may need emergency replacing
due to a fibrin - platelet thrombus which
may be demonstrated by a raised transoxygenator 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.