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ECMO… FOR HYPOXEMIA
Niall D. Ferguson, MD, FRCPC, MScHead of Critical Care Medicine
University Health Network & Mount Sinai Hospital
Professor, Departments of Medicine & Physiology,Institute of Health Policy, Management and Evaluation
Interdepartmental Division of Critical Care MedicineUniversity of Toronto
• 24M with subadventitial transection of thoracic
aorta and multiple orthopedic injuries due to
MVA
• Worsening respiratory failure (“shock lung”) after
4 days, despite maximal CMV
• Partial venoarterial perfusion via peripheral
cannulation using Bramson-membrane heart-
lung machine with flow 3.0-3.6 L/min for 75
hours
• PaO2 increased from 38 to 75 mmHg
• FiO2 decreased from 100% to 60%
• PIP reduced from 60 to 35 cmH2O
• Patient survived and was discharged to rehab
facility 8 weeks after ICU admission
Hill JD et al., N Engl J Med 1972;286:629634.
ECMO vs. Bypass
Cardiopulmonary bypass
• Heart stopped
• Systemic perfusion at low levels (e.g., 2 L/min)
• Necessitates total anticoagulation
• Membrane oxygenator has lifespan of hours
ECMO
• Higher blood flow rates (> 4L/min)
• Lower degree of anticoagulation possible
• Membrane oxygenator may last for days to weeks
Hollow Fiber “Membrane” Lung
Brodie D and Bacchetta M, N Engl J Med 2011;365:1905-1914.
Gas Exchange During ECMOCO2 Exchange (Air Flow Variable)
O2 Exchange (Blood Flow Variable)
Independent of blood flow Independent of sweep gas flow rate
Dependent on gas diffusion gradient Dependent on blood flow rate
Dependent on sweep gas flow rate Dependent on blood path thickness
Dependent on membrane surfacearea
Dependent on membrane diffusion thickness
Dependent on O2 concentration
Dependent on membrane surface area
Short BL and Williams L. ECMO Specialist Training Manuel 3rd Edition. (2010)
7
8
Oxygenation:
BLOOD FLOW
Ventilation:
SWEEP FLOW
Zapol WM et al., JAMA 1979;242:2193-2196.
ECMO + MV 4/42 = 9.5% (95% CI 3-23%)
MV alone 4/48 = 8.3% (95% CI 3-20%)
Survival Rates
Problems with Zapol et al.
VA rather than VV ECMO used
• May have contributed to high incidence of pulmonary micro-thrombosis and fibrosis in ECMO patients (due to lower pulmonary blood flow)
Aggressive anticogulation
• Severe bleeding and increased transfusion requirements
Lack of standard ventilatory strategy
• High rates of barotrauma
Late initiation of ECMO?
• Limited recovery in patients receiving injurious MV for > 7 days?
30-day survival (primary outcome):
New therapy (ECCO2R) 7/21 = 33%
Conventional MV 8/19 = 42%
(p = 0.8)
Problems with Morris et al.
Low-flow ECCO2R instead of higher flow ECMO• No extracorporeal oxygenation support and reliance on lungs
led to increase in airway pressures (no lung rest)
Lack of ECCO2R expertise• Study team had only used new therapy in sheep and 1
human prior to study
• Bleeding and thrombotic complications
PCIRV• Results have not been replicated in other severe ARDS
populations
What Changed Our Thinking About ECMO?
Bartlett RH et al., JAMA 2000;283:904-908.
Noah MA et al., JAMA 2011;306:1659-1668.
Total Patients Survived ECLS
ECLS Toronto Experience2000 – 2016
0
10
20
30
40
50
60
70
80
90
No o
f E
CL
S/
yr
Year
Cardiac / Other
ARDS (non-Tx)
BTR (Post)
BTT (pre)
19
ECMO is a bridge
2000-June2015 (YTD)*
0
10
20
30
40
50
60
70
80
No
of
EC
LS
/ y
r
Year
Cardiac / Other
ARDS (non-Tx)
BTR (Post)
BTT (pre)
Where Do We Go From Here?
21
22
Period Annual ECMO VolumeAdjusted OR for
Mortality
2008-2013
1-5 1
6-14 0.82 (0.64-1.05)
15-30 0.72 (0.55-0.96)
>30 0.61 (0.43-0.80)
Del Sorbo L and Ranieri VM. Crit Care Med 2010;38:S555-S558.Zwischenberger JB and Lynch JE. Lancet 2009;374:1307-8.
VS.
Expertise – patients transported to center of excellence –center effect??
Availability and cost-effectiveness?
Optimal patient population and timing of initiation?
Jones A et al., Lancet 2010;375:550-551.
N Engl J Med 2006;355:41-50.
JAMA 2009;302:1888-1895 Chest 2010;137:752-758.
30 patients
H1N1-associated ARDS
Median age 34
Median P/F ratio 61
Not treated with ECMO
68 patients
H1N1-associated ARDS
Median age 34
Median P/F ratio 56
Treated with ECMO (15 ICUs)
Survival 75% vs. Survival 73%
EOLIAECMO to rescue Lung Injury in severe ARDS
Characteristic Score
Age (years)18-4950-59≥ 60
0-2-3
Immunocompromised -2
MV prior to ECMO< 48 hours48 hours – 7 days> 7 days
310
Acute respiratory diagnosis groupViral pnemoniaBacterial pnemoniaAsthmaTrauma/burnAspiration pneumonitisOther acute respiratory diagnosisChronic respiratory and non-
respiratory diagnosis
33
113510
Characteristic Score
CNS dysfunction -7
Acute associated (non-pulmonary) infection
-3
NMBA before ECMO 1
NO before ECMO -1
NaHCO3 infusion before ECMO -2
Cardiac arrest before ECMO -2
PaCO2 (mmHg)< 75≥ 75
0-1
PIP (cm H2O)< 42≥ 42
0-1
TOTAL RESP SCORE -22 to 15
Schmidt M et al., Am J Respir Crit Care Med 2014;189:1374-1382.
30Derivation Validation
Current Limitations
All patients already on ECMO at experienced centers
• Need to focus also on who to (or not to) offer VV ECMO
Focus on longer-term mortality and morbidity
• Will be very useful in prognostication/decision-making when discussing treatment options with patients/family/surrogates
ECCO2R
Increased PEEP
Severe Hypoxemia in 6/15
pH and PCO2 within 10% of baseline
37
Conclusions
Support of patients with severe acute respiratory failure (bridge to recovery)
• Here to stay…. but applicable population still to be defined
Support of patients with acute on chronic respiratory failure awaiting lung transplant (bridge to transplant)
• Here to stay…. but careful with redo transplant cases
Facilitation of ultra-lung protective ventilation in moderate-severe ARDS patients
• Too early to call…. more data needed
40
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