Extracorporeal Membrane Oxygenation

Kamal K. Pourmoghadam, MD, Florida

Introduction

•ECMO uses venoarterial bypass with a membrane oxygenator
–Allows both hemodynamic and respiratory support
–Standard technique for pediatric extracorporeal life support (ECLS)

Equipment

•ECMO Support generally uses:
–Silicon membrane oxygenator
–Heat exchange
–Bladder
–Roller/centrifugal pump

Results

•ECMO Support generally uses:
–Silicon membrane oxygenator
–Heat exchange
–Bladder
–Roller/centrifugal pump

Candidates for ECMO

•ECMO has been traditionally analyzed by considering four separate subgroups
–Neonatal respiratory failure
–Pediatric respiratory failure
–Neonatal and pediatric cardiac failure
–Adult cardiorespiratory failure
•Indications for support, support strategy and outcomes differ drastically in each

Neonatal Respiratory Failure

•Indicators for ECMO in neonatal respiratory failure is based on degree of respiratory failure and response to conventional measures
•Oxygenation Index (OI) provides a useful measure for evaluation of these patients
OI = Mean Airway pressure x ([FiO2 x 100]/PaO2)
•OI >25 is associated with mortality of 50% when conventional modalities are used
•OI > 40 is associated with mortality of 80% when conventional modalities are used
•ECMO should be considered when OI > 25 accompanied with no clinical improvement, or when OI> 40
•Cannulation For Respiratory Failure
–Venous drainage through right internal jugular vein
•8-12F for neonates with side holes in RA
•Arterial cannulation through R common carotid artery
•Femoral cannula can be used as an adjunct or in children greater than 15 kg
–Alternatively many centers are gaining increasing experience with venovenous ECMO
•Significant conversion rate
•More feasible in larger children and adults
•Decannulation
–Many centers routinely ligate carotid artery and jugular vein
–Preference to repair
•Institutional
•Except in rare instances of local wound infection
–ECMO for Neonatal respiratory failure has declined
•Inhaled NO
–Approved by the FDA in December 1999
–High frequency oscillatory ventilation

Pediatric Respiratory Failure

•Small percentage of cases, 8.8%
•Survival to  separation from ECLS, 62%
•Survival to discharge, 55%
•Etiologies for ECMO
–Pneumonia
–ARDS
–Acute respiratory failure, non-ARDS
–Other forms of sepsis
–Severe tracheal disease

Neonatal and Pediatric Cardiac Failure

•14.2% of cases
•Survival to separation from ECLS, 53%
•Survival to discharge, 39%
•Cannulation
–Cervical
–Often transthoracic, RA and AO
•May decompress the left side (LV vent)
–LA appendage
–RSPV/LA
–Atrial septostomy
•ECMO Support was evaluated for three groups (Walters et al.)
–Patients on ECMO preoperatively
–Patients unable to wean from CPB and converted to ECMO
–Patients who were cannulated postoperatively after an initial period of stability
•ECMO support (Walters et al.):
–Hospital survival for all patients, 58%
–Group 2 survival to discharge, 23.5%
–Group 3 survival to discharge, 69.4%
“ ECMO is most effective in salvaging pediatric cardiac surgical patients who demonstrate medically refractory hemodynamic deterioration at some interval after being successfully weaned from cardiopulmonary bypass.”
•ECMO has also been used as an adjunct to pediatric cardiac transplantation
–Used as a bridge to transplant
–Used as a facilitation of allograft in immediate postoperative period
–Used as a complement therapy for rejection
–60 % survival, 35 % lived more than 8 months
•Children with cardiac failure and biventricular hearts have a higher success rate than those with single ventricle physiology
–Previously many considered single ventricle physiology as a contraindication to ECMO
•2% of all cardiac ECMO were HLHS, 1996
•Recent improvement results
–This group has grown to 28% of all cases
•Management of systemic to pulmonary artery shunt
–Controversial
•Occlude
•Partial occlusion (Jacobs et al.)
•Open (Ungerleider et al.)

Adult Cardiorespiratory Failure
•3.8 % of all cases of adult respiratory and adult cardiac failure
•Results of adult ECMO not as good as those in neonatal and pediatric population
•Survival to separation from ECLS, 47%
•Survival to discharge, 43%
–Adult respiratory failure
•Survival to separation from ECLS, 52%
•Survival to discharge, 48 %
–Adult cardiac failure
•Survival to separation from ECLS, 37%
•Survival to discharge, 32 %

Weaning  & Decannulation
•Performed under echo guidance to asses ventricular filling and function
•Flows are gradually turned down over several hours until flows of 25-40 ml/kg/min are reached
•Ventilator support and inotropic infusions are increased appropriately
•Arterial and venous cannulas are clamped
–Full anticoagulation is maintained
–Cannulas are intermittently flushed (every 15-20 minutes) as needed
•Until patient shows stability off ECMO
•Patient can be maintained off ECMO for 1-2 hours in this manner (intermittent flushing)
•In certain fragile patients with profound ventricular dysfunction, the weaning period can be extended over 48-72 hours, with gradual reduction in flow
–Fragile patients gradually accommodate to lower flows

Cardiopulmonary Support System
•Limitations of ECMO
–Prolonged set-up time (45-60 minutes)
–Large priming volume (450-800 ml)
–Increased postoperative blood loss
–Difficulty in transport
•Measures to counteract limitations
–Pre-priming the circuit
–Added risk of infection
–Cost
•ECMO used as rescue during acute cardiopulmonary failure
–Effectiveness depends on CPR duration
•CPR< 15 minutes, 100% survival
•CPR> 42 minutes, 55% survival
–Del Nido et al.
“ Success of resuscitation depends largely on the speed and recognition of the arrest event and the  establishment of effective respiratory and circulatory support.”

Summary
•Proper ECLS systems must be matched to the individual needs of the patient, personal experience of clinicians / surgeons, and the attributes of the institution
•Future evolution in ECLS system for children will involve
–Decreasing anticoagulation requirements
–More biocompatibility with smaller circuit /support systems
–Eventual development of compatible implantable support devices

About Dr. Kamal K. Pourmoghadam

Kamal Pourmoghadam, MD, is a pediatric cardiac surgeon at The Heart Center at Arnold Palmer Hospital for Children. He is board certified in general surgery, cardiothoracic surgery and congenital cardiac surgery.

Dr. Pourmoghadam earned his bachelor’s degree from University of California, Berkeley, and his medical degree from Albany Medical College in New York. He trained for adult cardiac surgery at the University of Miami, Jackson Memorial Hospital in Miami, and for congenital cardiac surgery at the University of Washington, Seattle Children’s Hospital in Seattle.

Dr. Pourmoghadam is a professor of surgery at the University of Central Florida College of Medicine, practicing congenital cardiac surgery for over twenty years and has been active in clinical research. He has extensive experience in neonatal and infant cardiac surgery and has special interest in the repair of single ventricle physiology patients and research in univentricular hearts.
References:

Website: https://kamalpourmoghadam.com
Blog: https://drpourmoghadam.home.blog/
News: https://hippocratesguild.com/dr-kamal-pourmoghadam
News: https://medicogazette.com/dr-kamal-pourmoghadam#425f92ce-0ccc-4fe2-8c31-56cf497704f4
News: https://hype.news/dr-kamal-pourmoghadam/
News report about Dr. Pourmoghadam: http://www.tiogapublishing.com/features/the_marketplace/covington-tot-returns-home-to-pennsylvania-after-lengthy-oklahoma-hospital/article_04865c00-0ae5-11e1-aec8-001cc4c002e0.html
Linkedin: https://www.linkedin.com/in/kamal-pourmoghadam-9a796157/

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