ECMO (Extracorporeal Membrane Oxygenation ) for Physicians

PRE-ECMO MANAGEMENT

ECMO Referrals

The DCH transport operator has an updated call schedule. The Medical Control Physician on-call is responsible for directing the call to the appropriate physician and assisting with transport. Any concerns regarding bed availability will be handled as a facility to facility communication. Helicopter transports will be handled by DCH if the pediatric team is available.

ECMO REFERRALS: WHEN TO CALL AND HOW TO TRANSPORT

One of the most difficult tasks for a referring physician and a consulting ECMO physician is to determine when a patient needs to be transferred to an ECMO center. The majority of infants with disease states frequently treated by ECMO improve without ECMO and, therefore, referral may not be necessary. The decision to transfer is an enormous responsibility that can be eased by early consultation with the ECMO center thereby allowing both teams to decide when to move a patient. However, when an infant is at high risk for failing maximal therapy, the referring physician should decide to transfer before the patient is too sick for transport.

The progression of respiratory insufficiency due to pulmonary hypertension is not linear. Deteriorating oxygenation will respond to increasing ventilatory parameters to a certain point; once this is exceeded (approximating ECMO criteria) there may be rapid progression to a refractory hypoxic cardiac arrest. To decrease the risk of death prior to transport, infants should be transferred prior to meeting ECMO criteria. Referral of infants on high frequency oscillatory ventilation should be at a time when they can be converted to conventional ventilation for transfer, for in most cases, infants cannot be transported on the oscillator. Most centers agree that if the infant has not improved on the oscillator after 6 hours of oscillation, that referral to an ECMO center should be considered. There are no standard criteria for transfer. An infant who cannot be adequately ventilated despite maximal mechanical support is a candidate for expedient transfer.

ECMO CONSULTATION

The referring physician should begin to consider the need for ECMO when a patient who has received appropriate medical management has a PaO2 of 50-60 mm Hg when the PIP is >35 cm H2O and the FiO2 is 1.00 for conventional ventilation, and after 6 hours of high frequency ventilation without improvement in oxygenation. After consultation with an ECMO physician the time of transfer can be determined through a team approach taking in to account such items as transport time, type of transport needed, and regional availability of ECMO beds.

The following selection criteria are criteria for initiating ECMO, not for deciding when to consult an ECMO center or to transfer a patient to an ECMO center.

Neonatal Referrals

All Neonate referral are handled directly through the NICU. The Neonatologist on call can be reached 24 hours a day at (361) 694-5330.

Neonatal ECMO Patient Selection Criteria
Gestational Age > 34 weeks
Birthweight > 2,000 grams
No significant coagulopathy or uncontrollable bleeding
No major intracranial hemorrhage
Mechanical Ventilation <10-14 days
Reversible lung disease
No Lethal Cardiac Lesions
No Lethal Congenital Anomalies
No Evidence of Irreversible Brain Damage

Neonatal ECMO Patient Qualifying Criteria
AaDO2 = atmospheric pressure –47- (PaCO2 + PaO2)/ FiO2
47 is the partial pressure of water vapor
600-624 torr for 4 to 12 hours at sea level

Oxygenation Index (OI) = MAP x FiO2 x 100 / PaO2
MAP is mean airway pressure
25-40 for ½ to 6 hours

PaO2
35-50 mm Hg for 2-12 hours

Acute Deterioration
PaO2 <30-40 torr
PH < 7.25 for 2 hours
Intractable hypotension

Pediatric Referrals

All Pediatric referrals are handled by the Pediatric ICU attending. The attending can be reached 24 hours a day at (361) 694-5320 or 1-800-879-KIDS (5437).

Eligibility Criteria for ECMO
Duration of Ventilation:
<2 years <10 days
2-8 years <8 days
>8 years <6 days
Respiratory Failure
PEEP >8 cm H2O x 12 hours
FiO2 > .8 x 12 hours
PaO2/FiO2 <150
P(A-a) O2> 450 mm Hg
Respiratory Acidosis
pH < 7.28 with
Peak Inpiratory Pressure 40 cm H2O or
Airleak Syndrome
Maximal minute ventilation without air trapping
Reasonable Medical Certainty of Quality of Life

Exclusion Criteria for ECMO
Age Days of Ventilation
<2 years >10 days
2-8 years >8 days
>8 years >6 days
Major hemorrhage
Immunosuppression
Cardiac arrest with neurologic impairment
Recent cerebral-vascular accident
Low certain of quality of life.

ECMO Criteria

Driscoll Children's Hospital follows the ELSO guidelines for ECMO.

Neonatal ECMO Guidelines

General Inclusion/Exclusion Criteria for ECMO
There are several important "inclusion" and "exclusion" criteria for ECMO based on known benefits and complications of the procedure.

Gestational age>34 weeks and Birth Weight >2000Grams
The requirement for systemic heparinization of the ECMO patient places significant limitations on the population treated. In the late 1960's and early 1970's ECMO was used for premature infants who weighed less than 2000 Grams and were less than 34 weeks gestation. This resulted in significant mortality and morbidity from intracranial hemorrhage. Although refinement of the procedure occurred in the early 1980's, the premature infant continued to have a significant risk of intracranial hemorrhage with ECMO therapy. This increased risk may be a result of the combination of systemic heparinization and altered cerebral circulation as a result of ECMO, or it may be due to primary disease entity causing cerebral ischemia in a susceptible infant. ECMO therapy, including heparin management, has been further refined in the 1990's. Although most ECMO centers will not treat the premature infant<34 weeks gestation, some centers are cautiously studying this population to see if they can be considered as ECMO candidates. Better understanding of effects of ECMO perfusion on the brain, in addition to new technical advances such as heparin-bonded circuits, may permit lowering the gestational age cutoff in the future. However, at the present time ECMO therapy is not recommended for infants <34 weeks gestation. Although 2000 grams is generally considered a minimum birth weight, small for gestational age infants < 34 weeks gestation should not be excluded based on weight only.
Lack of Significant Coagulopathy or Bleeding Complications
The requirement for systemic heparinization also places the infant with a significant coagulopathy or pre-existing bleeding complications, such as pulmonary hemorrhage, at extreme risk. All attempts should be made to correct any coagulopathy prior to the institution of ECMO. Severe coagulopathy that cannot be controlled or corrected with appropriate blood product replacement may be a relative contradiction for ECMO. Consultation with the ECMO center physician will help determine which infants should be excluded because of bleeding problems.

The septic infant is of concern because of the common association of coagulopathy. Although these infants are at a higher risk for bleeding complications on ECMO, treatment of their coagulopathy and meticulous heparin management have allowed these infants to be successfully treated. Early consultation is important for this group of infants because they can deteriorate quickly making transfer difficult.

Many infants who have blood-tinged tracheal aspirate fluid before ECMO can be managed on bypass with higher peak and expiratory pressures (PEEP) and modified heparin administration. The infant with an uncontrolled massive pulmonary hemorrhage prior to ECMO should generally not be considered a candidate. Almost all deaths on ECMO are related to a bleeding complication. Consultation with an ECMO center is the best way to determine if a given patient's coagulation defect would contradict treatment.
No Major Intracranial Hemorrhage
The need for heparin therapy also precludes the treatment of infants with major intracranial hemorrhage. An infant with a Grade I intraventricular hemorrhage (IVH) or a small parenchymal hemorrhage can be treated with lower heparin therapy and close monitoring of activated clotting times. Centers may vary on the definition of Grade I vs. Grade II IVH. Consultation with your ECMO center is suggested before an infant is denied ECMO because of pre-existing IVH.
Mechanical Ventilation Less than 10-14 Days and Reversible Lung Disease
More than 10-14 days of assisted ventilation prior to ECMO is a relative contradiction to the procedure. It is known that lung fibrosis and/or chronic lung changes occur with prolonged mechanical ventilation and exposure to high oxygen concentrations. The exact timing of these changes vary per child, thus clinical considerations must determine when the lung disease is no longer reversible in a relative short period. Chronic lung injury cannot improve or completely reverse within the time period that ECMO can be used safely. Although the length of time that an infant can safely stay on the ECMO circuit is not known, most centers limit the duration of ECMO to less than 30 days because of increased risk of complications after approximately 14 days of therapy. Chronic lung diseases that do not improve in a short time period should not be treated with ECMO unless there is a superimposed. Life-threatening acute disease state such as pulmonary hypertension which can be reversed by ECMO. Early consultation allows time for the referring and ECMO physicians to judge progression of the disease and possibly intervene before irreversible lung injury occurs.
No Uncorrectable Cardiac Lesion
An important component of the pre-ECMO evaluation is an echocardiogram to rule out 1(inoperable cardiac disease, 2) anomalies in which ECMO support provides little benefit, or 3) operable cardiac lesions without significant lung disease which require surgical treatment, not ECMO. Select infants with congenital heart disease may be candidates for ECMO pre-repair of their cardiac anomaly. ECMO may stabilize a patient and allow proper studies, even cardiac catheterization. ECMO may also be used to treat associated lung disease and make neonates better candidates for surgery.
No Lethal Congenital Anomalies
ECMO centers may vary in their definition of congenital anomalies that are incompatible with life and, therefore, contraindicate the use of ECMO. When an infant is born with an unusual, potentially lethal anomaly, early discussions between referring and ECMO physicians may help to define the appropriateness of ECMO therapy.
No Evidence of Irreversible Brain Damage
Irreversible brain damage can be difficult to determine. Consultation with the ECMO center physician can assist in this determination.

HIGH MORTALITY RESPIRATORY CRITERIA

The statement "after maximal medical therapy" has many caveats, but once an infant is failing conventional therapy for respiratory insufficiency, ECMO should be considered. Based on retrospective data from their own institutions, most
ECMO centers utilize specific criteria that attempt to predict a high percent mortality without ECMO. Because these criteria assume the use of therapeutic techniques that may be available only at the ECMO center, these criteria have
limited application at the referring hospital. In addition, infants allowed to meet ECMO criteria before transfer have an increased risk of death because deterioration may result very rapidly once baseline ECMO criteria are met.

Commonly used criteria are:

-Alveolar-arterial (A-a) oxygen gradient over a specific time period
-Oxygen Index (OI) over a specific time period
-PaO2 levels less than 50 mm Hg over a limited time period

Infants are sometimes placed on ECMO using the criterion of "acute
deterioration." In most centers this means placing on ECMO an infant who is in
impending or full cardiopulmonary arrest. This includes patients who have PaO2's
less than 30mm Hg with or without hypotension.

AaDO2 = P-47 –PaCO2- PaO2 where P is the barometric pressure and 47 is the
pressure of water vapor, when FiO2 is 1.00.
OI= MAPx FIO2 x 100/ PaO2 where MAP is the mean airway pressure.

STUDIES RECOMMENDED PROIR TO TRANSFER FOR ECMO

Cardiac evaluation by ultrasound (if available at your institution) should be performed to identify uncorrectable heart disease that would contraindicate the use of ECMO. Other diagnostic studies that should be done prior to transfer of the ECMO candidate include:

-Head ultrasound (within 24 hours) to rule out a significant intracranial hemorrhage
-Tests of coagulation status including a partial thromboplastin time (PTT), prothrombin time (PT), fibrinogen, fibrin degradation products (FDP), and platelet count.
-Calcium and electrolyte levels
-White blood cell count with differential
-Hemoglobin and hematocrit levels
-Blood type and cross
These baseline studies will provide additional information to the ECMO
consultant and help to define possible difficulties.

TRANSPORT OF THE ECMO CANDIDATE

Early consultation with the ECMO center will allow for the logistics of transport to be completed in a timely fashion. At the time of the initial consultation the referring center and the ECMO physician should determine a contingency plan for support. The distance between hospitals, the availability of the ECMO bed, and the stability of the patient will be important factors in determining which team will transport and what type of transport vehicle will be used.

IN SUMMARY

Early consultation with an ECMO center is encouraged and should result in appropriate and safe transfer of the potential candidate prior to the infant's actually meeting criteria for the institution of ECMO therapy.

Contact Information:

Co- Directors of Driscoll Children's Hospital's ECMO Program:

J. Mark Morales, MD - Chief of Cardiothoracic and Director of Perfusion Services
Office: (361) 854-0201

Mark Bielefeld, MD - Chief of Staff
Office: (361) 854-0201

Karl Serrao, MD, FAAP
Office: (361) 694-5445
Pager: (361) 851-7794