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P AR A S K H AN DH A R S E N I O R T A L K

ECMO (ExtracorporealMembrane Oxygenation )

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When I think about Ecmo, I think

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ECMO in Adults? Isnt this a Peds thing?

y 1000 patients supported on ECMO at the Universityof Michigan were reviewed (retrospectively)

y VV-ECMO for respiratory failure provided survival todischarge:

88% of 586 cases of respiratory failure in neonates

70% for 132 cases of respiratory failure in children

56% for 146 cases of respiratory failure in adults

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Introduction

y Mechanical circulatory support has evolved markedlyover recent years.

y ECMO (extra corporeal membrane oxygenation) hasbecome more reliable with improving equipment, andincreased experience, which is reflected in improving

results.

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Introduction

y ECMO is instituted for the management of lifethreatening pulmonary or cardiac failure (or both),

when no other form of treatment has been or is likelyto be successful.

y ECMO is essentially a modification of thecardiopulmonary bypass circuit which is usedroutinely in cardiac surgery.

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Introduction

y Instituted in an emergency or urgent situation afterfailure of other treatment modalities.

y It is used as temporary support, usually awaitingrecovery of organs.

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Dynamics of ECMO

y Blood is removed from the venous system eitherperipherally via cannulation of a femoral vein orcentrally via cannulation of the right atrium,

Oxygenate Extract carbon dioxide

y Blood is then returned back to the body either

peripherally via a femoral artery or centrally via theascending aorta.

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Indications for ECMO

y Divided into two type

Cardiac Failure

Respiratory Failure

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Indications Cardiac Failure

y Post-cardiotomy

when unable to get pt off cardiopulmonary bypass followingcardiac surgery

y Post-heart transplant usually due to primary graft failure

y Severe cardiac failure due to almost any other cause

Decompensated cardiomyopathy

Myocarditis Acute coronary syndrome with cardiogenic shock

Profound cardiac depression due to drug overdose or sepsis

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Indications Respiratory Failure

y Adult respiratory distress syndrome (ARDS)

y Pneumonia

y Trauma

y Primary graft failure following lung transplantation.

y ECMO is also used for neonatal and pediatric

respiratory support This is where most of the research on ECMO has been done

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Decision to Institute ECMO

y Several considerations must be weighed: Likelihood of organ recovery.: only appropriate if disease process is

reversible with therapy and rest on ECMO

Cardiac recovery: to either wait for further cardiac recovery to allow

implant of device (LVAD) or to list for transplantation. Disseminated malignancy

Advanced age

Graft vs. host disease

Known severe brain injury

Unwitnessed cardiac arrest or cardiac arrest of prolonged duration.

Technical contraindications to consider: aortic dissection or aorticincompetence

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Configurations for ECMO

y ECMO can be inserted in 2 configurations:

Veno-venous

Veno-arterial

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y Veno-arterial (VA) configuration

Blood being drained from the venous system and returned tothe arterial system.

Provides both cardiac and respiratory support. Achieved by either peripheral or central cannulation

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Central ECMO Cannulation

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y Veno-Venous (VV) configuration

Provides oxygenation

Blood being drained from venous system and returned tovenous system.

Only provides respiratory support

Achieved by peripheral cannulation, usually of both femoralveins.

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Peripheral ECMO Cannulation

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Central vs. Peripheral Cannulation

y Advantages

Flow from Central ECMO is directly from the outflow cannula

into the aorta provides antegrade flow to the arch vessels,coronaries and the rest of the body

In contrast, the retrograde aortic flow provided by peripheralleads to mixing in the arch.

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y Disadvantages

Previously insertion of central ECMO required leaving chestopen to allow the cannulae to exit.

Increased the risk of bleeding and infection

Newer cannulae are designed to be tunneled through the subcostalabdominal wall allowing the chest to be completely closed.

Central cannula are costly (approximately 4 times as much asperipheral)

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Things to Think About

y Mechanical ventilation must be continued during ECMOsupport to try to maintain oxygen saturation of bloodejected from the left ventricle to at least above 90%.

y ECMO flow can be very volume dependent

y ECMO flow will drop:

Hypovolemia Cannula malposition

Pneumothorax

Pericardial tamponade.

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Weaning of ECMO VV ECMO

y Actual ECMO flows do not need to be altered to assessnative respiratory function

Done by altering gas flow through the ECMO circuit

y Pt may be weanable:

Gas exchange is able to be maintained with a low FiO2 (

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Weaning of ECMO VA ECMO

y Depends on cardiac recovery, Factors:

Increasing blood pressure

Return or increasing pulsatility on the arterial pressure waveform

Falling pO2 by a right radial arterial line

indicating more blood is being pumped through the heart which maybe less well oxygenated,

Falling central venous and/or pulmonary pressures.

y It is important to note that cardiac outputs frompulmonary artery catheter are inaccurate on ECMO Most of the circulating blood volume is bypassing the pulmonary

circulation

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Complications

Falls into one of three major categories

1) Bleeding associated with heparinization

2) technical failure

3) neurologic sequelae

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Complications of ECMO

y Bleeding/Hemolysis

Out of proportion to the degree of coagulopathy and patientplatelet count

y Coagulopathy

Continuous activation of contact and fibrinolytic systems by thecircuit

Consumption and dilution of factors within minutes of initiationof ECMO

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Complications of ECMO

y Thrombocytopenia

Platelets adhere to surface fibrinogen and are activated

Resultant platelet aggregation and clumping causes numbers todrop

y Non-pulsatile perfusion to end organs Kidneys

Splanchnic circulation seems to be particularly susceptible

GI bleeding, ulceration and perforation

Liver impairment

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Complications of ECMO

y Mechanical Complications

Tubing rupture

Pump malfunction

Cannula related problemsy Local complications: Leg ischemia

Particularly at peripheral insertion site of VA

y Air embolism/Thromboembolism

y Neurological: Intracerebral bleeds Largely associated with sepsis

Manifest as seizures or brain death

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Management of Complications

y Regular measurements of blood tests (Q6-Q8h)

Coagulation Profile

Platelet Count

Hemoglobin Creatinine to evaluate for renal insufficiency

y Aggressive replacement of clotting factors,

electrolytes, PRBC

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Outcomes of ECMO

y Good quality RCT of ECMO outcomes in adultpopulation are lacking

y There are very promising studies in the Pediatricpopulations, however it is hard to know if thistranslates into the adult population.

y Completed yet unpublished CESAR Trial showssome potential impact in ECMO research

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CESAR

y Conventional Ventilation or ECMO for Severe AdultRespiratory Failure

y Preliminary results released at 37th Society of CriticalCare Medicine Congress in Honolulu February2008

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CESAR

y Randomized controlled trial to assess the impact ofECMO on survival without severe disability by6

months in patients with potentially reversiblerespiratory failure

y Severe disability was defined as confined to bed and

unable to dress or wash oneself

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CESAR

y Conducted from 2001-2006

y Adults were randomized either to VV ECMO at

Glenfield Hospital, Leicester, England (90 patients)or continuing conventional care at referral hospitals(90 patients).

y The conventional group underwent standard clinicalpractice in the UK Conventional Ventilator

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CESAR

y ECMO

57 of 90 met primary endpoint

y Conventional ventilation group 41 of87 met primary endpoint

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CESAR

y RRR0.69 (95% CI, 0.050.97;P = 0.03)

y Benefit of ECMO seen regardless of age, duration of

high-pressure ventilation, primary diagnosis at trialentry, and number of organs failing.

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Further Studies

y CESAR study shows potential impact for VV ECMO,however studies to evaluate impact for VA ECMO arelacking

y This is where potential studies can be done

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Summary

y ECMO is instituted for the management of lifethreatening pulmonary or cardiac failure (or both),

when no other form of treatment has been or is likelyto be successful.

y ECMO is essentially a modification of thecardiopulmonary bypass circuit which is usedroutinely in cardiac surgery.

y ECMO can be inserted in 2 configurations: Veno-

venous & Veno-arterialy Completed yet unpublished CESAR Trial shows

some potential impact in ECMO research

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Questions??

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Bibliography

y Bartlett RH. Extracorporeal life support registry report 1995. ASAIO J 1997;43:1047.y Conrad SA, Rycus PT, Dalton H. Extracorporeal life support registry report 2004.

ASAIO J 2005;51:410.y Fiser S, Tribble CG, Kaza AK, Long SM, Zacour RK, Kern JA, Kron IL. When to

discontinue ECMO for postcardiotomy support. Ann Thorac Surg 2001;71:2104.y Glauber M, Szefner J, Senni M, Gamba A, Mamprin F, Fiocchi R, Somaschini M,

Ferrazzi P. Reduction of haemorrhagic complications during mechanically assistedcirculation with the use of a multi-system anticoagulation protocol. Int J Artif Organs1995;18:64955.

y Hitt E. CESAR trial: extracorporeal membrane oxygenation improves survival inpatients with severe respiratory failure. Medscape Medical News www.medscape.com;2008

y Marasco SF, Esmore DS, Negri J, Rowland M, Newcomb, A, Rosenfeldt F, Bailey M,Richardson M. Early institution of mechanical support improves outcomes in primary

cardiac allograft failure. J Heart Lung Transplant 2005;24(12): 203742.y Peek GJ, Clemens F, Elbourne D, Firmin R, Hardy P, Hibbert C, Killer H, Mugford M,

Thalanany M, Tiruvoipati R, Truesdale A,Wilson A. CESAR: conventional ventilatorysupport vs. extracorporeal membrane oxygenation for severe adult respiratory failure.BMC Health Serv Res 2006;23(6):163.

y www.emedicine.comy www.uptodate.com