3. 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.
4. 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
5.
6. ECMO PRINCIPLE
• Desaturated blood is drained via a
venous cannula
• CO2 is removed, O2 added throughan
“extracorporeal”device
• The blood is then returned to systemic
circulation via another vein (VV ECMO)
or artery (VA ECMO).
7. • 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.
8. ECMO CIRCUIT & COMPONENTS
The basic components of ECMO circuit includes
• a blood pump
• membrane oxygenator
• heat exchanger
• Controller and in line monitors
• cannulas
• tubings
9.
10.
11. PUMPS :
• The pump works both to push blood through the oxygenator and back to the patient
and also to augment venous outflow to the circuit.
• Two types of pumps are used in the ECMO circuit:
• the centrifugal pump
• the roller pump
12. CENTRIFUGAL PUMPS :
The centrifugal pump consists of:
• A set of cones
• A magnetic disc.
• Vortex effect
The flow is variable and is dependent on:
• the blood volume from the patient
• size of venous outflow cannulae
• size of the disc head
• pump speed.
13. ROLLER PUMPS
• The roller pump compresses the circuit tubing and pushes the blood through the raceway
of the pump.
The flow from the roller pump is dependent on:
• the size of the tubing in
the raceway
• occlusion pressure
of the rollers
• pump speed
• blood volume.
14. ROLLER PUMPS
Able to set totally or Partially occlusive
Positive displacement – pushes blood
by squeezing raceway
Flow = (stroke volume x rpms)
Flow is not dependent on resistance
CENTRIFUGAL PUMPS
Non – occlusive
Passive displacement
Cones or impellers create kinetic energy using
centrifugal force of fluid constrained vortexing
Rpm’s are proportional to resistance
Flow is inversely proportional to resistance
15. MEMBRANE
OXYGENATOR :
• ECMO circuits have a gas exchange
device called oxygenator, to add
Oxygen and remove CO2 from
blood.
• V/Q Mismatch.
16. Two different devices have been developed for gas exchange:
• the silicone membrane oxygenator
• the hollow fiber oxygenator (HFO).
Silicone membrane oxygenator consists of a thin silicone sheath separated by a plastic screen
spacer.
17. • 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.
18. Oxygen exchange is dependent on:
• thickness of the blood film
• membrane material
• fraction of inspired oxygen (FIO2)
• hemoglobin concentration.
Carbon dioxide removal depends on
• The sweep: higher sweep speeds result in
higher CO2 removal.
• The flow: if the flow is increased without
increasing the sweep, then CO2 removal can
be impeded.
• The presence of water vapour in the
membrane: this can impede CO2 removal.
19. 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.
20. BRIDGE
• The bridge is a connection between the
venous (drain) and arterial (return)
components of the circuit.
• Bypass to allow the isolation of the
patient from the circuit.
• This allows the circuit to continue to flow
thereby reducing the risk of clot
formation when weaning the patient off
the circuit.
21. IN-LINE MONITORS MONITORS
• Continuous measurement of flow rate, pH, oxygen saturation, and PCO2 have been
built into the ECMO circuit, on both the venous and arterial sides.
• Activated clotting time (ACT) analyzers are also built into the system to ensure that
the proper clotting time is maintained. Unless contraindicated, the circuit is infused
with heparin to prevent clot formation.
• Commonly used parameters range from 180 to 220 seconds or 1.5 times the normal
range.
22. CONTROLLER PANEL
• The controller allows the operator of the
ECMO circuit to adjust the settings as
needed. The settings that are typically
adjusted are:
• The RPM: The higher the RPM, the
higher the rate of blood flow through
the pump.
• The sweep: More gas entering the
oxygenator allows for better CO2
removal.
• The controller has a pole-mounted
graphic display that allows the
adjustment of the pump RPM.
23. CANNULAS
Drainage and Return Cannulas:
• The drainage cannula allows blood to flow through
the pump to the oxygenator.
• The return cannula returns blood from the
oxygenator to the patient.
• The typical adult ECMO circuit handles anywhere
between 1-6 litres per minute of blood flow, so large
bore cannulas are needed to accommodate this.
24. The key points about the drainage and return cannulas are:
• They are typically 23-29 French (about 7.5 - 10 mm in diameter)
• The larger and shorter the cannula, the less resistance to flow it has
• Drainage cannula are situated in large central veins, typically IVC, SVC, or the right atrium
• Depending on the configuration, return cannula are situated either in the right atrium, or in the
aorta
• The drainage cannula often have multiple orifices so they drain all along their length.
25. TUBINGS
:
• Depending on the heparin
coating, they are of 2 types :
• - regular
• - heparin coated
26. TYPES
There are 2 separate modes of access for ECMO:
• Venovenous (V-V) : isolated respiratory failure
• Veno-arterial (V-A) :isolated cardiac failure or combined cardiopulmonary
failure.
• A dialysis membrane can be added to either circuit to provide simultaneous
continuous renal replacement therapy
27.
28. The main principles of V-V ECMO are :
• Deoxygenated blood is drained from a large central vein, and oxygenated blood is
returned to the right atrium or another large central vein.
• Does not bypass the heart or the lungs.
• Provides no hemodynamic support, the patient’s native cardiac function must be
intact
• Typically used in hypoxic respiratory failure. The most common reasons are:
• ARDS refractory to conventional management.
• Primary Graft Dysfunction after a lung transplant.
• Hypoxia in the context of severe lung disease as a bridge to lung transplantation.
29.
30. • In V-A ECMO:
• The ECMO circuit is connected in parallel with the heart and lungs: blood going through
the ECMO circuit bypasses the heart and lungs.
• Blood that doesn't go through the ECMO circuit travels through the heart and lungs, and
mixes with the ECMO circuit blood in the aorta.
• The pulsatility of the blood flow to the patient's tissues is markedly reduced.
• Typically used in low cardiac output states refractory to conventional therapies. The most
common reasons for V-A ECMO are:
• Myocardial ischemia
• Dilated cardiomyopathy
• Persistent ventricular tachyarrhythmias
• Myocarditis
• End stage pulmonary arterial hypertension
31. • As a result of this configuration, two parallel circulations are created:
• Blood passing through the native heart and lungs that is ejected into the aorta
• The oxygen content of this blood depends on adequate oxygenation and ventilation by the
lungs.
• Blood passing through the ECMO circuit that is returned into the abdominal aorta
• Assuming the membrane oxygenator is working properly, this blood will be richly
oxygenated.
32. • Blood from these two parallel circulations will mix somewhere in the aorta, and
their relative contributions to systemic oxygen delivery is a function of how much
flow is going through each circulation.
• Territories most vulnerable to hypoxia are those with blood supply from the
proximal aorta.
• The coronary arteries supplying the myocardium.
• The innominate artery supplying the right arm and the brain.
• The left common carotid artery supplying the brain
33.
34.
35. 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.
36. ELSO GUIDELINES FOR ADULT
RESPIRATORY FAILURE
• INCLUSION CRITERIA:
1. In hypoxic respiratory 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.
37.
38. 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
39. 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.
40. •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
.
41. 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
-Acute myocardial infarction
-Myocarditis
-Decompensated chronic cardiac failure
-Post cardiotomy shock
-Peripartum cardiomyopathy
• Septic shock
42. CONTRAINDICATIONS
• ABSOLUTE :
-Unrecoverable heart & not a candidate for transplant /VAD
-Chronic and severe organ dysfunction (Emphysema, cirrhosis, renal failure)
-Prolonged CPR without adequate tissue perfusion
• RELATIVE :
-Anticoagulation
-Obesity
-Advanced age
43. PAEDIATRIC INDICATIONS AND CONTRAINDICATIONS
• ECLS should be considered in patients with marginal or inadequate gas exchange at risk of ventilator-
induced lung injury and who are failing less invasive therapy.
• Specifically:- severe respiratory failure as evidenced by sustained PaO2/FiO2 ratios <60-80 or OI>40
where OI = {mean airway pressure (cmH2O) x FiO2 (%)} / PaO2 (mmHg)
• Lack of response to conventional mechanical ventilation ± other forms of rescue therapy (eg. high
frequency oscillatory ventilation (HFOV), inhaled nitric oxide, prone positioning)
• Elevated ventilator pressures (eg. mean airway pressure >20-25 on conventional ventilation or >30 on
HFOV or evidence of iatrogenic barotrauma)
44. • Absolute contraindications
• - Lethal chromosomal abnormalities (eg. Trisomy 13 or 18)
• - Severe neurological compromise (eg. intracranial hemorrhage with mass effect)
• - Allogeneic bone marrow transplant recipients with pulmonary infiltrates
• - Incurable malignancy
• Relative contraindications
• - Duration of pre-ECLS mechanical ventilation >14 days (4,7)
• - Recent neurosurgical procedures or intracranial hemorrhage (within the last 1-7 days,depending on
neurosurgical advice)
• - Pre-existing chronic illness with poor long-term prognosis and MODS
• High risk patients
• - Infants with pertussis pneumonia or disseminated herpes simplex
• - Cytomegalovirus infection and severe coagulopathy or thrombocytopenia
45. STARTING ECMO
• Vascular Imaging
• Location
• Equipment
• Patient preparation:
1. The patient should have central venous access prior to cannulation.
2. The patient should have invasive hemodynamic monitoring prior to cannulation.
3. Anesthesia
4. Anticoagulation: The patient must be systemically anticoagulated with heparin,
typically a 5000 unit bolus.
46. ECMO CANNULATION
• The cannulation process for V-V ECMO and peripheral V-A ECMO is carried out
using the Seldinger Technique.
• For central V-A ECMO, the return cannula is placed via a sternotomy and direct
placement into the thoracic aorta.
• When the cannulas are appropriately placed, they are joined to the ECMO circuit
tubing by placing the two ends together while pouring saline over them to ensure no
air is entrained into the circuit.
47. CANNULA VERIFICATION:
• It is important to verify that the cannulas
are placed correctly, as this can have a
large impact on the hemodynamics.
Cannula placement can be verified in the
following ways:
• X-ray
• Transthoracic echocardiography
• Transesophageal echocardiography
48. DAILY CARE OF THE ECMO PATIENT: CIRCUIT SETTINGS
Flow
• Flow is not directly controlled by the pump, instead the pump is set to a certain RPM. In general, the higher RPM
the higher the flow.
• A rule of thumb is that the flow in mL/min is about +/- 500 mL higher than the RPM of the pump. For example, if
the pump is at 3000 RPM, then the flow through the pump should be anywhere from 2500 to 3500 mL/min.
Consider trying to increase the flow if:
• There are signs of hypoxemia, e.g. decreased SpO2, decreased PaO2.
• There are signs of decreased perfusion of tissue e.g. elevated lactate, decreased urine output (V-A ECMO only).
Consider trying to decrease the flow if:
• The patient is showing recovery of intrinsic ability to oxygenate.OR recovery of cardiac function (V-A ECMO only).
• There is significant hemolysis and the pump speed is above 4500 RPM.
• There is significant chatter and the flow rates are erratic (this may mean your pump speed is too high and it is
causing "suckdown" of the return cannula vessel).
49. Sweep
• The sweep gas rate controls the rate of CO2 removal.
• The FiO2 of the sweep gas helps control the PaO2.
• Sweep gas flow rates vary between 0-15 litres per minute.
Sweep gas adjustments should be considered in the following scenarios:
• The patient develops relative hypercarbia: sweep gas should be increased.
• The patient develops relative hypocarbia: the sweep gas should be decreased.
• The patient develops hypoxemia: the FiO2 of the sweep gas may be increased.
• The patient demonstrates increased work of breathing: the sweep gas may be increased
(although this may not work to relieve the work of breathing).
50. Blood Pressure:
• The blood pressure should be measured invasively, traditionally in the right radial
artery if the patient is on V-A ECMO.
• Just like in any ICU patient, the MAP should be maintained at a high enough level
to allow for adequate organ perfusion.
• Vasopressors and inotropes may be used in ECMO patients in similar doses to
patients who are not on ECLS.
Laboratory Values:
The following should be measured daily:
• CBC
• ABG
• Electrolytes
• Creatinine
• Lactate
52. MECHANICAL VENTILATION
• Apply the same principles of lung protective
ventilation to ECLS patients .The main
things to keep in mind are:
• Limit the FiO2 as hyperoxia can cause
reabsorption atelectasis and damage lung
tissue.
• Keep the plateau pressures low to protect
the lungs from barotrauma.
• Use low tidal volumes to protect the lung
from volutrauma.
• Maintain PEEP to avoid atelectrauma and
total consolidation of the lung.
53. WEANING & TRIAL OFF OFECMO
• 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.
54. -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.
The following steps happen:
• The sweep gas flow to the oxygenator is reduced to zero.
• The patient is observed for signs of respiratory distress.
• The tidal volumes, minute ventilation and respiratory rate are measured on the
ventilator.
• The patient's vital signs are monitored.
• Serial blood gases are taken to monitor the gas exchange of the native lungs
55. -VA ECMO trials
-The cause of cardiogenic shock should be resolved.
• A minimum of 24-48 hours on V-A ECMO before trying to wean.
• MAP > 70 mmHg.
• Low doses of vasopressors and inotropes.
• Oxygen saturation > 95%.
• Central venous saturation > 70%.
• Resolving pulmonary edema.
• LVEF >25-30%.
• Normal right ventricular function.
• Blood lactate level low and not increasing.
56. • 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%
• Need temporary clamping of both drainage and infusion lines, while
allowing to circulate through a bridge between the arterial and venous
limbs.
• The patient is continuously monitored for signs of inadequate cardiac output:
• Rise in filling pressures
• Elevation of blood lactate
• Hypoxemia
• High inotrope and/or vasopressor requirements
• Decreased central venous saturation
• Echocardiographic signs of right or left ventricular dysfunction
57. COMPLICATIONS
• Bleeding
• Thromboembolism
• Cannulation related
• Heparin induced thrombocytopenia
• VV ECMO specific complications
• VA ECMO specific complications
• Neurological complications
58. COMPLICATIONS
CIMPLICATION SIGN ACTION
Large thrombus formation Dark or white areas on
oxygenator/tubing connectors,
increase pressure gradient across
oxygenator
Change oxygenator or circuit,
increase heparin infusion
Cannulae complication
Venous cannulae too close to one
another (V-V ECMO
No color difference between
venous and arterial cannulae
X-ray confirmation. Pullback
cannula
Arterial cannula in ascending
aorta
Aortic valve insufficiency, left
ventricular failure
X-ray and echocardiographic
confirmation. Pullback cannula
Hypovolemia, pneumothorax,
pericardial tamponade
Chatter’’ (shaking) of cannulae Hypovolemia: Administer Fluids,
decrease ECMO flow;
pneumothorax: thoracostomy
tube; pericardiac tamponade:
pericardiocentesis and/or
pericardial window
59. CIMPLICATION SIGN ACTION
Air embolism
Venous Lack of blood flow (airlock) Stop ECMO flow. Change
circuit or oxygenator.
Arterial Stroke, hypotension Stop ECMO flow.
Trendelenburg position
Oxygenator failure Increase gas or pressure
gradient across the
membrane, thrombocytopenia,
hemolysis
Replace oxygenator
Pump failure Decrease blood flow/pump
speed
Manually hand crank the
pump and replace pump or
power source
Hemorrhagic stroke Little clinical evidence. Brain
CT scan needed
Prevent hypertension and
excessive anticoagulation
Lower extremity ischemia
(with V-A ECMO)
Cool, pale extremity, signs of
compartment syndrome (late),
rhabdomyolysis (late)
Use smaller bore femoral
arterial cannula, place shunt
from the arterial cannula
directed to distal femoral
artery
60. •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.
61. 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.
62. 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.
63. VV ECMO SPECIFICCOMPLICATIONS
• 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
64. 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.
65. THE HARLEQUIN SYNDROME (NORTHSOUTH 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
66. 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.
67. • 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.
