Extracorporeal Membrane Oxygenation - Introduction to General Medicine - Lecture Slides, Slides of Medicine

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ECMO (Extracorporeal

Membrane Oxygenation )

ECMO in Adults? Isn’t this a Peds thing?

 1000 patients supported on ECMO at the University of Michigan were reviewed (retrospectively)

 VV-ECMO for respiratory failure provided survival to discharge:  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

Introduction

 ECMO is instituted for the management of life threatening pulmonary or cardiac failure (or both), when no other form of treatment has been or is likely to be successful.

 ECMO is essentially a modification of the cardiopulmonary bypass circuit which is used routinely in cardiac surgery.

Introduction

 Instituted in an emergency or urgent situation after failure of other treatment modalities.

 It is used as temporary support, usually awaiting recovery of organs.

Indications for ECMO

 Divided into two type

 Cardiac Failure

 Respiratory Failure

Indications – Cardiac Failure

 Post-cardiotomy  when unable to get pt off cardiopulmonary bypass following cardiac surgery

 Post-heart transplant  usually due to primary graft failure

 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

Decision to Institute ECMO

 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 aortic incompetence

Configurations for ECMO

 ECMO can be inserted in 2 configurations:

 Veno-venous

 Veno-arterial

 Veno-Venous (VV) configuration  Provides oxygenation  Blood being drained from venous system and returned to venous system.  Only provides respiratory support  Achieved by peripheral cannulation, usually of both femoral veins.

Central vs. Peripheral Cannulation

 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 peripheral leads to mixing in the arch.

Things to Think About

 Mechanical ventilation must be continued during ECMO support to try to maintain oxygen saturation of blood ejected from the left ventricle to at least above 90%.

 ECMO flow can be very volume dependent

 ECMO flow will drop:  Hypovolemia  Cannula malposition  Pneumothorax  Pericardial tamponade.

Weaning of ECMO – VV ECMO

 Actual ECMO flows do not need to be altered to assess native respiratory function  Done by altering gas flow through the ECMO circuit

 Pt may be weanable:  Gas exchange is able to be maintained with a low FiO2 (<30%)  Low fresh gas flow rates into the circuit (<2 L/min)

 Caveat: RR and PEEP set on ventilator are not too high (e.g. <25 breaths/min and <15cmH2O, respectively).

Complications

Falls into one of three major categories

1. Bleeding associated with heparinization

2. technical failure

3. neurologic sequelae

Complications of ECMO

 Bleeding/Hemolysis

 Out of proportion to the degree of coagulopathy and patient platelet count

 Coagulopathy  Continuous activation of contact and fibrinolytic systems by the circuit  Consumption and dilution of factors within minutes of initiation of ECMO