ECMO - extracorporeal membrane oxygenation

EXTRACORPOREAL MEMBRANE
OXYGENATION
(ECMO)
-Dr. PRAPULLA CHANDRA D

• INTRODUCTION
• HISTORY
• PRINCIPLE
• CIRCUIT & COMPONENTS
• INDICATIONS
• CONTRAINDICATIONS
• ECMO MECHANISM
• COMPLICATIONS
• OUTCOMES OF ECMO
• EXTRA CORPOREAL CO2 REMOVAL
• EXTRA CORPOREAL CPR

INTRODUCTION
• A form of extracorporeal life support where an external artificial
circuit carries venous blood from the patient to a gas exchange
device (oxygenator) where blood becomes enriched with oxygen
and has carbon dioxide removed.
• The blood is then returned to the patient via a central vein or an
artery.
SOURCE : ECMO guidelines AlfredHealth Update nov 2015

55
History of Extracorporeal Life Support
1950s Development of membrane oxygenator in laboratory
1971 First successful case
1972 First successful paediatric cardiac case
1975 First neonatal case (Esperanza)
1975-89 Trial in ARDS, 10% survival
1990 Standard practice for neonates and paediatrics in
some centres
2000 Standard practice for adults in some centres
2009 Publication of the CESAR trial which led to a significant
growth in the use of ECMO for ARDS cases

First successful ECMO patient in1971
Figure 3.4. The first successful extracorporeal life support patient, treated by J. Donald
Hill using the Bramson oxygenator (foreground), Santa Barbara, 1971.

First Neonatal ECMO survivor..

ECMO PRINCIPLE
• Desaturated blood is drained via a venous cannula
• CO2 is removed, O2 added through an
“extracorporeal” device
• The blood is then returned to systemic circulation
via another vein (VV ECMO) or artery (VA ECMO).

• ECMO serves as a BRIDGING THERAPY and not a curative therapy.
• Used as a
-bridge to recovery :– i.e., buying time for patient to recover
-bridge to decision :- provide temporary support to patient and
allow clinicians to decide on the next step.
-bridge to transplant :- provide support to patient while awaiting
suitable donor organ.

ECMO CIRCUIT & COMPONENTS
• The basic components of ECMO
circuit includes
• - a blood pump
• - membrane oxygenator & heat
exchanger
• -controller
• -cannulas
• -tubings

PUMPS :
• They are basically of 3 types.
• - Roller pump
• - Impellar pump
• - centrifugal pump

CENTRIFUGAL PUMPS :
• Roller pumps are now being
replaced by centrifugal pumps.
• The perfusion pressure is
controlled by RPM (0-4000 RPM)
• Can deliver flow upto 8 L/min
• Very reliable upto 21 days.

Membrane Oxygenator :
• ECMO circuits have a gas
exchange device called
oxygenator, to add Oxygen and
remove CO2 from blood.

• Previously, silicon membrane
oxygenators were used which
are being replaced by Hollow
fibre PMP(polymethyl pentene)
membrane oxygenators.
• These are extremely efficient at
gas exchange and demonstrate
minimal plasma leakage, low
resistance to blood flow.

GAS EXCHANGE :
OXYGEN exchange depends on :
• Type of membrane & diffusion
characteristics
• Thickness of the blood pathway
• Surface area of the membrane
• FiO2 in the gas phase
• Rate of blood flow
CO2 exchange depends on :
• Difference in CO2 conc. between
blood and gas
• Size of membrane
• Fresh gas flow
• Blood pathway thickness
• Blood flow rate

HEAT EXCHANGER :
• In adults, it is usually built within the oxygenator.
• In paediatric cases, it is connected separately after the
oxygenator in the circuit.
• It is used for temperature regulation of the extracorporeal
blood.

• Controller panel for pressure
monitoring and blood gas
moitoring

TUBINGS :
• Depending on the heparin
coating, they are of 2 types :
• - regular
• - heparin coated

2525
Different CONFIGURATIONS in ECMO
Most common configurations:
• Veno-Venous ECMO (VV-ECMO):
• Used to support patients with severe respiratory failure refractory to
conventional therapies
• Blood is drawn from a central vein, pass through an ECMO machine and
then returned back via a central vein
• Veno-Arterial ECMO (VA-ECMO):
• Used to support patients with severe cardiac failure (with or without
respiratory failure)
• Blood is drawn from a central vein, pass through an ECMO machine and
then returned back via a central artery
ECMO guidelines AlfredHealth Update nov 2015

• Arterio-Venous ECMO (AV ECMO) :
An arteriovenous (AV) extracorporeal circuit that uses the
patient’s own arterial pressure or incorporates a pump to drive
blood across an oxygenator can partially support the
respiratory system by effectively removing carbon dioxide
(CO2) (extracorporeal CO2 removal [ECCO2R]).

VENO-VENOUS ECMO (VV ECMO)
• Venous blood is accessed from large central veins, pumped through
the oxygenator and returned to the venous system near right atrium.
• There are 4 configurations of VV-ECMO depending on the cannulation
sites.
a) Femoro-femoral
b) high flow
c) femoro-jugular
d) double lumen single canula (Avalon)

Femoro-Femoral :
• Access cannula is inserted via the
femoral vein with the tip sited within
the ivc.
• Return cannula is inserted via
contralateral femoral .v with the tip in
right atrium.
• Advantages : quick and safe to insert,
easy to secure cannulae.
• Disadvantages : limited maximum flow
rates, often requires conversion to a
high flow configuration.

High Flow :
• Uses the same bi-femoral cannulation.
• An additional short access cannula is
inserted via the right internal jugular vein
with tip in svc.
• Advantages : allows higher circuit blood
flows as they draw blood from the great
veins (svc & ivc).
-It is required in severe cases of
respiratory failure when single access
canula circuit flow is inadequate to
maintain sufficient levels of gas exchange.

• Disadvantages :
-occupies 3 veins.
- relatively complex to secure and dress the jugular cannula.
- patient remains bed bound.
- potential source of air embolism and pressure injury.

Femoro-Jugular :
• Access cannula – via femoral vein
with tip sited just below the inferior
cavo-atrial junction.
• Return cannula – into right internal
jugular vein with the tip in lower
svc.
• Advantages : nearly can provide
adequate support (5-7 l/min).

• Disadvantages :
- relatively complex to secure and dress the jugular
cannula.
- requires two sterile fields to be done during ECMO
cannulation.
- access insufficiency can be more difficult to identify in
early stages without negative pressure monitoring.

Double lumen/Two stage single cannula
( Avalon ):
• Single cannula with two lumens for
access and return inserted via the
right internal jugular vein.
• Advantages : single vein
cannulation. Allows movement
from bed and ambulation.
• Disadvantages : care on insertion to
avoid right ventricular
placement/rupture. Difficult to
position return port towards the
tricuspid valve.

VENO-ARTERIAL ECMO (VA-ECMO)
• Venous blood is accessed from the large central veins, pumped through
oxygenator and returned to the systemic arterial system in the aorta.
• It provides support for severe cardiac failure with or without associated
respiratory failure.
• Different configurations of VA ECMO are :
-standard Femoro-Femoral
-emergency Femoro-Femoral
-High Flow
-Central : specialised cannula
-Central : Bypass cannula

Standard Femoro-Femoral :
• Access cannula is inserted via femoral vein
with tip in right atrium.
• Return cannula : via common femoral artery
with tip lying in common iliac artery or
lower aorta.
• Advantages : provides full or partial cardiac
support.
• Disadvantages : risk of differential hypoxia –
may need conversion to high flow
configuration if native cardiac function
improves in the setting of significant
respiratory failure.

Emergency Femoro-Femoral :
• Similar to standard femoro-femoral but uses SMALLER cannula
which are quicker to insert in an emergency.
• Standard cannula : 21-25 Fr
Emergency cannula : 19-21 Fr
Advantages : faster to insert. Used for ECMO-CPR or in peri-arrest
patients.
Disadvantages : risk of differential hypoxia.

High Flow :
• Uses the same bi-femoral
cannulation with additional access
cannula inserted via the right
internal jugular vein with tip in svc.
• Advantages : used to minimise
differential hypoxia when native
cardiac function improves.

INDICATIONS OF ECMO
• ELSO GUIDELINES:
-Acute severe cardiac failure or respiratory failure with high
mortality risk and reversible and non-responsive to optimal
conventional therapy.
-ECLS is considered at 50% mortality risk and indicated at 80% risk.
SOURCE : ELSO General Guidelines Version 1.3 December 2013
ELSO- EXTRA CORPOREAL LIFE SUPPORT ORGANIZATION

ELSO GUIDELINES FOR ADULT RESPIRATORY
FAILURE
• INCLUSION CRITERIA:
1. In hypoxic resp failure due to any cause (primary or secondary)
a) 50% mortality risk associated with a PaO2/FiO2 < 150 on FiO2 >90%
and Murray score 2-3
b) 80% mortality risk is associated with a PaO2/FiO2 <100 on FiO2 >90%
and Murray score 3-4 despite optimal care for 6 hrs or more.
2. CO2 retention on Mechanical Ventilation despite high Pplat (>30cm H2O)

3. Need for intubation in a patient on lung transplant list
4. Immediate cardiac or respiratory collapse (Pulmonary Embolism,
blocked airway) unresponsive to optimal care.

Parameter / Score 0 1 2 3 4
PaO2/FiO2
(On 100%
Oxygen)
≥300mmHg
≥40kPa
225-299
30-40
175-224
23-30
100-174
13-23
<100
<13
CXR normal 1 point per quadrant infiltrated
PEEP(cmH2O) ≤5 6-8 9-11 12-14 ≥15
Compliance
(ml/cmH2O)
≥80 60-79 40-59 20-39 ≤19
ECMO inclusion criteria - Murray score
= average score of all 4 parameters

INDICATIONS :
Reversible Respiratory Failure :
• ARDS
• Severe Pneumonias
• Severe Acute Asthma
• Chemical and Inhalation hypersensitivity Pneumonitis
• Near Drowning
• Post traumatic Lung Contusion
• Bronchiolitis Obliterans
• Autoimmune lung diease - Vasculitis, Good Pasture Syndrome

Irreversible or Chronic Respiratory Failure :
• It is indicated as a bridge, only when-
-patient is for lung assist device. Eg : PAL (paracorporeal artificial
Lung)
-patient is waiting for lung transplant.

•CONTRAINDICATIONS :
• No absolute contraindications to ECLS in respiratory failure.
• Relative contraindications due to poor outcome are :
- Mechanical Ventilation at high settings ( FiO2 >90%, P-plat >30) for 7 days or
more.
- Major pharmacological immunosuppression (absolute neutrophil count <
400/mm3)
- CNS haemorrhage which is recent or expanding
- Non recoverable co-morbidity such as major CNS damage or terminal
Malignancy
-Age : no specific age contraindication but increasing risk with age
SOURCE : ELSO General Guidelines Version 1.3 December 2013.

ELSO GUIDELINES FOR CARDIAC FAILURE :
• Cardiogenic shock
-inadequate tissue perfusion manifested as hypotension and low
cardiac output despite adequate intravascular volume.
-shock persists despite volume administration, ionotropes and
vasoconstrictors and intraaortic balloon counterpulsation if
appropriate.

typical causes :
-Acute myocardial infarction
-Myocarditis
-Decompensated chronic cardiac failure
-Post cardiotomy shock
-Peripartum cardiomyopathy
• Septic shock

• ECMO advantages in cardiac failure :
-Biventricular support, Bedside immediate application and
oxygenation in Biventricular failure, Refractory malignant arrhythymias,
heart failure with severe respiratory failure.
• ECMO is a Bridge to
Recovery : Acute MI after revascularisation, Myocarditis,
Postcardiotomy
Transplant :Unrevascularizable acute MI, Chronic heart failure
Implantable circulatory support : VAD

CONTRAINDICATIONS
• ABSOLUTE :
-Unrecoverable heart & not a candidate for transplant /VAD
-Chronic organ dysfunction (Emphysema, cirrhosis, renal failure)
-Prolonged CPR without adequate tissue perfusion
• RELATIVE :
-Anticoagulation
-Obesity
-Advanced age

ECMO MECHANISM
• It includes :
-INITIATION
-MAINTENANCE
-DISCONTINUATION

INITIATION
• Once it has been decided to initiate ECMO, the patient is anticoagulated
with i/v heparin and cannulae are inserted according to the ECMO
configuration ( VV or VA ECMO)
• Following cannulation, patient is connected to ECMO circuit, the pump
started with the flow of 20 ml/kg/min and gradually increased every 5-
10 min by 10 ml/kg/min to reach the desired flow.
• Gas flow to blood flow ratio is adjusted to 0.5 : 1 & start with FiO2 of
21%  100% FiO2.
• Once desired flow achieved, ventilator settings are brought down to
base line.
SOURCE : ECMO UPTODATE 2013

• Reasonable targets are :
- an arterial oxy Hb saturation of- >90% for VA ECMO,
>75% for VV ECMO
- A venous oxy Hb saturation of 70-80% for VA ECMO
-Adequate tissue perfusion as determined by arterial blood pressure,
venous oxygen saturation and blood lactate level.
SOURCE : ECMO UPTODATE 2013

MAINTENANCE & MONITORING:
• Once the initial respiratory and hemodynamic goals have been achieved,
blood flow is maintained at that rate.
• Continuous venous oxymetry, Pressure monitoring (MAP, prepump P, pre
and post oxygenator P), vital parameters (HR, RR, TEMP), Flow rates
(blood flow rate at 60-150 ml/kg/min), neurological status, vascular
status to be monitored.
• Anticoagulation is sustained during ECMO with a continuous infusion of
unfractionated heparin, titrated with activated clotting time(ACT) of 180-
210 sec.

WEANING & TRIAL OFF OF ECMO
• INDICATIONS :
-For patients with Respiratory failure, improvements in radiographic
appearance, pulmonary compliance and arterial oxyHb saturation.
-With cardiac failure, enhanced aortic pulsatility correlates with
improved left ventricular output.
-One or more trials of taking the patient off of ECMO should be
performed prior to discontinuing ECMO permanently.

• Decrease flow in steps to 1 L/min at FiO2 100% or decrease flow to 2L/min then
decrease sweep gas FiO2 to maintain SaO2 >95%
• When SaO2 stable on these settings,
- VV ECMO trials are performed by eliminating all countercurrent sweep gas through
oxygenator. Blood flow remains constant, but gas transfer doesnot occur. Ventilator
settings are adjusted.
- VA ECMO trials need temporary clamping of both drainage and infusion lines, while
allowing to circulate through a bridge between the arterial and venous limbs.
- VA ECMO trials are generally shorter duration than VV ECMO trials because of higher
risk of thrombus formation.

COMPLICATIONS
• Bleeding
• Thromboembolism
• Cannulation related
• Heparin induced thrombocytopenia
• VV ECMO specific complications
• VA ECMO specific complications
• Neurological complications

• BLEEDING :
- Occurs in 30-40% of patients on ECMO
- Due to continuous heparin infusion and platelet dysfunction.
treatment :
-maintaining platelet count > 1 lakh/mm3, target ACT reduces the
risk of bleeding.
- surgical exploration if major bleeding occurs.
- if bleeding occurs, decrease heparin infusion & maintain ACT at
160 sec.
- plasminogen inhibitors can be given but may increase risk of
circuit thrombosis.

THROMBOEMBOLISM :
• It is more common with VA ECMO
than VV ECMO as infusion is into
systemic circulation.
• A sudden change in pressure
gradient indicates thrombus
formation.

CANNULATION RELATED :
• Vessel perforation with
haemorrhage.
• Arterial dissection
• Bleeding
• Distal ischemia in VA ECMO
-treatment : inserting distal
perfusion cannula in femoral
artery distal to ECMO cannula.

HEPARIN INDUCED THROMBOCYTOPENIA
• HIT can occur in patients receiving ECMO.
• When HIT is proven, heparin infusion should be replaced by
non-heparin anticoagulant.

VV ECMO SPECIFIC COMPLICATIONS
•RECIRCULATION :
-Here, reinfused blood is withdrawn through the drainage cannula
without passing through the systemic circulation.
- The degree of recirculation determines the efficiency of ECMO in
providing oxygenation.
INTERVENTION :
- Increasing the distance between cannulae
- Use of single site double lumen cannula
- Addition of another drainage cannula
SOURCE : ELSO guidelines for management of recirculation May 2015

VA ECMO specific complications
• Pulmonary haemorrhage
• Cardiac thrombosis
-retrograde blood flow in the ascending aorta in VA ECMO.
-stasis of blood can occur if left ventricular output is not maintained
leading to thrombosis.
• Coronary or cerebral hypoxia
-coronary usually gets blood from native circulation (from LV)
-With compromised LV & LUNGS, relatively hypoxic perfusion
occurs.

THE HARLEQUIN SYNDROME (north south
syndrome)
• Saturation of upper part of the body is lower than that of lower half.
• This is due to flow competition in the aorta
– recovering heart vs ECMO pump
High cardiac output from native recovering heart prevents the
retrograde flow of ECMO to perfuse upper part.
If pulmonary function is impaired :
-”BLUE HEAD” : deoxygenated blood to upper part
-”RED LEGS” : hyperoxygenated blood to lower part

In case of respiratory failure, flow competition in the aorta between the recovering native heart
and the extracorporeal circuit can lead to a “Harlequin” or “North–South” syndrome.
Christopher Lotz et al. Circulation. 2014;130:1095-1104
Copyright © American Heart Association, Inc. All rights reserved.

• TREATMENT :
-increase the ECMO flow if no cardiac stunning
-higher ventilator setting or consider HFOV (High Frequency
Oscillatory Ventilation)
-switch to VV ECMO if persistent lung failure.

Chest X-ray belongs to a 19-yr-old female with ARDS on VV-ECMO.
Guillermo Martinez, and Alain Vuylsteke Contin Educ
Anaesth Crit Care Pain 2011;bjaceaccp.mkr056
© The Author [2011]. Published by Oxford University Press on behalf of the British Journal of
Anaesthesia. All rights reserved. For Permissions, please email:
journals.permissions@oup.com

Published online : 16 September 2009

CESAR TRIAL
• Randomized control trial of adult ECMO vs Conventional
Ventilatory support.
• Adults were randomized either to VV ECMO at Glenfield
Hospital, Leicester, England (90 patients) or continuing
conventional care at referral hospitals (90 patients) i.e.,
conventional ventilator support.
Peek GJ, et.al. Lancet 2009;374:1351‐136

ECMO
• 57 out of 90 met primary end
point.
• Survival rate at 6months is
63%
• Mortality 37%
CONVENTIONAL VENTILATORY
SUPPORT
• 41 of 87 met primary
endpoint
• Survival rate at 6months is
47%
• Mortality 53%
Peek GJ, et.al. Lancet 2009;374:1351‐136

United Kingdom H1N1
ECMO vs Conventional care
• 69 ECMO patients in 4 centers
•Conclusion: ECMO survival 76%
Conventional Care 49%
Noah JAMA 2011, 366:1659

• 68 patients with severe influenza associated ARDS were treated with
ECMO.
• Out of 68, -influenza A - 61 (H1N1 -53)
-Not subtyped -7
• Survival rate : 71% (48 out of 68)

EXTRACORPOREAL CO2 REMOVAL (ECC02R)
• The process by which an extracorporeal circuit is used for the primary
purpose of removing CO2 from the body, thereby providing partial
respiratory support.
• First described in 1977 by Kolobow and Gattioni.
• Where as ECMO is indicated in treating refractory hypoxemia in
severe cases of ARDS, ECC02R is indicated to facilitate protective
ventilation in all stages of ARDS.

EXTRACORPOREAL CPR
• It is a method of cardiopulmonary resuscitation that uses
ECMO as an adjunct to standard CPR.
• The application of ECMO allows the return of cerebral
perfusion in a more suitable manner than with external
compressions alone.

SURGERY IN PULMONARY TUBERCULOSIS
ON 05-02-2016
FRIDAY
BY DR. SANDEEP

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