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

HISTORY

55

History of Extracorporeal Life Support 1950s Development of membrane oxygenator in laboratory1971 First successful case1972 First successful paediatric cardiac case1975 First neonatal case (Esperanza)1975-89 Trial in ARDS, 10% survival1990 Standard practice for neonates and paediatrics in

some centres

2000 Standard practice for adults in some centres2009 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..

Esperanza, Age 1 day 1975 Esperanza, age 21

FROM THIS

TO THIS

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 2013ELSO- 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)

SOURCE : ELSO General Guidelines Version 1.3 December 2013

3. Need for intubation in a patient on lung transplant list4. 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 pumpHigh 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: [email protected]

OUTCOMES OF ECMO

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.

CHEER TRIAL

ECMO PROCEDURE

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ECMO - extracorporeal membrane oxygenation