Mobile ECMO program begins

Jeanne Braby, RN, MSN, CCRN, Pediatric Intensive Care Unit, Children's Hospital of Wisconsin.

The development of a mobile extracorporal membrane oxygenation (ECMO) program was identified as an essential component of the expanding cardiovascular surgery program at Children's Hospital of Wisconsin. The mobile ECMO program was designed specifically for use as a back up for cardiothoracic procedures done by Children's Hospital surgeons at outreach institutions where we have established relationships, including Marshfield Clinic in Marshfield, Wis. and Loyola University Medical Center in Maywood, Ill. Although great care is taken to operate on children with mild to moderate heart disease at these locations, it is sound medical practice to have a backup support system to address medical needs that may exceed the resources of outreach institutions. An example of a patient who might need this service would be a child who is unable to successfully come off cardiopulmonary bypass, or one who decompensates in the early postoperative period and needs to be placed on ECMO. Since these outreach hospitals do not have ECMO programs, the child would be placed on ECMO at the outreach hospital by Children's Hospital cardiothoracic surgeons and perfusionists, and then transported back to Children's Hospital for further management in the Pediatric Intensive Care Unit (PICU). Although it is wise to prepare for this type of event, our cardiothoracic team never has had this occur with a patient at the outlying centers.

Planning for this service has been ongoing for the past few years. The first step in the planning process involved consultation with existing mobile ECMO teams. There currently are only four other pediatric centers in the United Sates that provide mobile ECMO. These are the University of Michigan C.S. Mott Children's Hospital in Ann Arbor, Mich., Arkansas Children's Hospital in Little Rock, Ark., Miami Children's Hospital in Miami, and Wilford Hall Medical Center in San Antonio. There are major differences between services offered by those ECMO centers and what will be offered at Children's Hospital. First, the other centers have the capability of transporting ECMO patients by air with a helicopter or fixed wing. At Children's Hospital, the existing Flight for Life helicopter is much smaller than those used by the other mobile ECMO teams, and is not able to accommodate an ECMO patient with all of the additional equipment and personnel needed. Because of this, Children's Hospital only will provide ground or ambulance ECMO transport.

The second major difference is that the other mobile ECMO teams will go to hospitals to rescue a child or adult in respiratory and/or cardiac failure. These teams will cannulate or place children or adults on ECMO at the referral hospital. The Children's Hospital mobile ECMO team will not be used to rescue patients with ECMO. There are many patients who are referred to Children's Hospital for consideration of ECMO who never actually require ECMO, but improve with other less invasive medical treatment. Early referral to Children's Hospital is requested so that traditional transport can occur and other advanced therapies offered at Children's Hospital can be attempted. These include nitric oxide and high frequency oscillatory ventilation. In addition, the Children's Hospital mobile ECMO team will not have the necessary equipment or systems in place to cannulate a patient at another facility. Instead, mobile ECMO will be used only as a back up for the cardiovascular team for children who already are on ECMO at Marshfield or Loyola. Finally, the Children's Hospital ECMO team is not designed to have the response time necessary for a patient who needs urgent cannulation.

Taking these differences into consideration, we designed a mobile ECMO program with the main objective of providing care in the safest way possible. With the help of Matt Scanlon, MD, patient safety program director and critical care intensivist at Children's Hospital and assistant professor of Pediatrics at the Medical College of Wisconsin, a Failure Modes and Effects Analysis (FMEA) was performed to identify risks associated with the initiation of a mobile ECMO program. (FMEA is a valid tool used in evaluating processes for potential safety or failure risks.) The intent of the FMEA was to identify those steps in an ECMO transport that have an increased risk of failure and to consider the implications of failure. The goal was to identify hazards and suggest steps to eliminate them. As a result of the FMEA, multiple procedural and equipment checklists have been developed.

With the primary goal of safety, representatives from clinical engineering (Terry Hensler and Tim Walther) and members of the perfusion team (Patrick Vanderwal and Chris Brabant) collaborated to design a custom ECMO cart that could be used on the ambulance. The cart has a five-foot stretcher and is self-contained with everything needed for an ECMO patient. Equipment on the cart includes a centrifugal ECMO pump (Biomedicus 550), patient ventilator (Pulmonetics LTV), eight medication syringe pumps (Baxter AS50), patient monitor and defibrillator (GE DASH), saturation/hematocrit monitor (Biotrend) oxygen and air tanks, water heater (Gaymar T pump), and a Universal Power Supply (UPS) back up unit (Clary). With the exception of the water heater, all of the equipment has internal batteries. The Clinical Engineering Department has been extensively involved with both the planning and implementation of the equipment. Electrical power analysis was done on all equipment, and a chart was developed with this information. In addition, a mock run with the pump/circuit setup was done in a moving ambulance to define how motion effected the equipment.

Another step taken to ensure safe patient transport on mobile ECMO involved the introduction of two new Medacare ambulances that are capable of transporting a mobile ECMO patient. The new ambulances were modified and configured with the mobile ECMO cart specifications. The empty cart weighs about 450 pounds, so an ambulance lift is necessary. The ambulances also are equipped with a back-up generator. Another useful piece of equipment on the ambulance is an ISTAT point of care testing device that will be used for blood gas and electrolyte analysis. The perfusionist will bring a hemochron machine for analysis of activated clotting times and heparin management.

Calls for a mobile ECMO patient will go through the Children's Transport and Physician Referral Center. This service is considered urgent and not an emergent service since the patient already will be on ECMO at the referring hospital. This will allow time for the essential team members to be assembled. The essential team consists of a cardiovascular surgeon or fellow, ECMO-trained transport physician, transport nurse clinician, perfusionist and transport respiratory care practitioner. The cardiopulmonary support clinician also will accompany the team if space permits.

In order to prepare for the potential ECMO transport, a small dedicated team has volunteered to be on call for a potential ECMO transport in 2004. Team members who already have participated in mock runs on the ambulance are nurses Jeanne Braby, Heather Nelson and Laura Westley, perfusionists Chris Brabant and Jim Groneck, respiratory care practitioner Nora Badertscher, critical care intensivist Nancy Ghanayem, MD, and cardiovascular surgeon Robert Jaquiss, MD. Ghanayem also is an assistant professor of Pediatrics and Jaquiss is an assistant professor of Surgery at the Medical College. Periodic mock runs will continue to be held on a quarterly basis to maintain competency. Although it is unlikely that we will have to use the mobile ECMO service, should it be needed as a back up, we will be able to provide it safely.

Monophasic vs. biphasic defibrillation

Alexis Sullivan, RN, BSN, Pediatric Intensive Care Unit, Children's Hospital of Wisconsin

In 2001, the American Heart Association's (AHA) Emergency Cardiovascular Care Committee, Wisconsin Region, made recommendations to the Emergency Medical Systems (EMS) for Children Committee regarding pediatric defibrillation.

Trying to limit the amount of myocardial damage that can occur from using higher energy levels, researchers are trying to determine what is considered safe in using automated external defibrillators (AEDs) in the pediatric populations. Monophasic and biphasic AEDs deliver energy doses of 120-200 jovles, which exceeds the recommended dose of two to four jovles/kg in children 8 to 12 years old. Biphasic shock energies (less than 200 jovles) appear to be safer at lower peak currents. The AHA also recommends adult AEDs be used on patients 8 years or older and weighing more than 25kg.

Incidence
Ventricular fibrillation (VF) is an uncommon cause of out-of-hospital pediatric cardiac arrests, but in-hospital studies of pediatric cardio pulmonary resuscitation (CPR) show that VF is not a rare rhythm in children in cardiac arrest as either the initial rhythm or as a rhythm occurring at the same time during the arrest. Studies indicate that 6 to 18 percent of pediatric terminal cardiac rhythms are VF.

Pediatrics vs adults
Pediatric advanced life support recommends AEDs can be used for children 1 to 8 years old with no signs of circulations. Ideally the device should deliver a pediatric dose and the arrhythmia detection algorhythm used in the device should demonstrate high specificity for pediatric shockable rhythms. Insufficient evidence exists for a recommendation on patients younger than 1 year old.

Several defibrillation options exist including both internal and external.

Internal

• Implanted automatic internal cardioverter/defibrillator (AICD).
• Transesophageal defibrillation.
• Open chest internal cardiac defibrillation.

External

• Manual conventional defibrillators.
• Automatic external defibrillators.

All depolarize the myocardium followed by a brief period of asystole and reinstitution of intrinsic cardiac automaticity.

Impedance
Defibrillation depolarizes a critical mass of myocardium with current flow that increases with higher energy (jovles) and decreases with higher impedance or resistance (ohms).

Factors increasing impedance include:

1. Using a paddle or electrode pad that is too small.
2. Large lung volumes.
3. Lack of conducting gel on paddles or electrode pads.

Impedence can be decreased by:

1. Electrical conducting gel.
2. Increased paddle pressure, which improves skin/
3. electrode contact and squeezes air from the lungs.
4. Repeated shocks may decrease impedance by increasing blood flow after every shock.
5. Increased paddle or electrode pad size reduces impedance and increases total current flow, but not necessarily increase current to the myocardium because paddles or electrode pads larger than the cross-section of the heart may bypass much of the current past its target through extramyocardial pathways. Evidence suggests that children have higher thoracic impedance than expected based on weight alone. The current dose of two jovles/kg may, in fact, be somewhat low and it is thought that risk of myocardial damage from this dose also is lower.

Monophasic vs. biphasic
For about 35 years, there was only one type of transthoracic defibrillator with a standard dampened sinc wave monophasic shock (an electrical pulse that flows one way between two electrode patches or paddles). Recently, biphasic waveforms have been incorporated into defibrillators using a smaller shock that effectively defibrillates. The current (amps) is divided into two phases, so the biphasic waveforms reverse the polarity partway through the pulse. This waveform has been used in internal pacemakers for many years.

Biphasic defibrillators deliver shocks with lower peak currents than monophasic shocks of the same energy. Peak current, not the energy delivered, is most closely associated with the damage to the heart from a defibrillator shock. Most manufacturers use biphasic waveforms in their automated and manual defibrillators.

The AHA recommends a monophasic energy dose of two to four jovles/kg for children. Manual defibrillators with biphasic waveform technology include operating guidelines for pediatrics. Biphasic shock averages 30 to 40 percent less peak current than monophasic waveforms maintaining the same energy levels.

First pediatric cardiology fellows begin

Peter Frommelt, MD, pediatric cardiologist and director of the pediatric fellowship program, Herma Heart Center, Children's Hospital of Wisconsin; associate professor, Pediatrics (Cardiology), Medical College of Wisconsin.

Children's Hospital, in conjunction with the Medical College of Wisconsin, began offering a pediatric cardiology fellowship program in July 2004, to further the education of pediatricians specializing in heart care.

The first two cardiology fellows are Matthew Brown, MD, and Beth Ann Johnson, MD.

Brown, who originally is from Salt Lake City, most recently completed a pediatric residency at Children's Mercy Hospital in Kansas City, Mo. He received his medical degree from The University of Utah School of Medicine in Salt Lake City. He elected to give up a pediatric chief residency appointment at Children's Mercy Hospital to join our program.

Johnson, who originally is from Rockford, Ill., most recently finished her second year of fellowship training in Neonatal/Perinatal Medicine at Children's Hospital of Wisconsin. She received her medical degree from the University of Illinois, Champaign, and a master's degree from the Medical College of Wisconsin, Milwaukee. Johnson also completed a residency in Pediatrics at the University of Texas, San Antonio. She will have the opportunity to be board certified in both Neonatology and Pediatric Cardiology at the completion of this fellowship program.

For more information about the cardiology fellowship program, call (414) 266-6457.

Herma Heart Center and Medical College of Wisconsin collaborate on translational research projects

Stuart Berger, MD, medical director, Cardiology, Herma Heart Center, Children's Hospital of Wisconsin; associate professor, Pediatrics (Cardiology), Medical College of Wisconsin

I am very proud to announce the establishment of a collaboration between Herma Heart Center at Children's Hospital of Wisconsin and the Cardiovascular Center (formerly the Cardiovascular Research Center) at the Medical College of Wisconsin. This exciting collaboration was kicked off at a joint meeting Oct. 4, 2004, and is destined to propel translational research and training to a higher level. World leaders individually, the centers will collaborate in research initiatives designed to define and treat mechanisms of pediatric cardiovascular disease.

The collaboration came to fruition over the past year, but the concept originated and was developed over a five-year period, aided by David, Harder, PhD and David Gutterman, MD, the director and associate clinical director, respectively, of the Cardiovascular Research Center.

The intent of the first meeting was to present some of the research and clinical problems that go on within the scope of the care of children with cardiopulmonary diseases. Organizing the event were Andrew Pelech, MD, pediatric cardiologist, and Kathleen Mussatto, RN, BSN, manager of cardiothoracic research at Children's Hospital. Individuals from Children's Hospital who presented our research included Pelech, Janette Strasburger, MD, pediatric cardiologist at Children's Hospital-Fox Valley, John Gordon, MD, critical care intensivist, Peter Frommelt, MD, pediatric cardiologist, and George Hoffman, MD, medical director of Anesthesiology. All physicians also are on the faculty at the Medical College.

Though this collaboration initially was begun to support research collaboration with the new accredited pediatric cardiology fellowship program, it became apparent that collaborative efforts between all individuals involved at both centers would improve care and outcomes of patients with cardiovascular diseases. Future meetings will occur on a regular basis with discussion of research and clinical problems. All interested individuals are welcome to attend these regular research conferences and discussions.

This collaborative association is anticipated to attract significant federal support, as interdisciplinary and translational research initiatives are key funding interests of the current NIH Roadmap to Accelerate Medical Discovery and Improve Health. It also serves as a good model for future interdisciplinary initiatives facilitated through the new Children's Hospital Clinical Research Institute.

Research update

Kathy Mussatto, RN, BSN, research manager, Herma Heart Center, Children's Hospital of Wisconsin

Research findings demonstrating the link between perioperative hemodynamics and later neurodevelopmental outcomes in children with hypoplastic left heart syndrome recently were presented at the American Academy of Pediatrics annual meeting by Nancy Ghanayem, MD, and at the American Society of Anesthesiology Annual Meeting by George Hoffman, MD. Ghanayem is a pediatric intensivist at Children's Hospital of Wisconsin and an assistant professor of Pediatrics at the Medical College of Wisconsin. Hoffman is medical director of Anesthesiology at Children's Hospital and an associate professor of Anesthesiology at the Medical College. These data support the hypothesis that early postoperative hemodynamic vulnerability identified by low systemic venous oxygen saturation (SvO2) contributes to adverse neurologic outcome after the Norwood procedure. Efforts to aggressively treat low SvO2 may improve neurologic outcomes for these children.

Several new studies have been initiated by Herma Heart Center researchers, two of which are summarized below.

Analysis of atrial natriuretic peptide, brain natriuretic peptide, and endothelin-1 in pediatric patients undergoing total cavopulmonary repair - Principal investigator, Joseph Cava, MD, PhD, pediatric cardiologist, Herma Heart Center, Children's Hospital; associate professor, Pediatrics, Medical College.

Following the Fontan procedure (total cavopulmonary connection) there is elevated central venous pressure, which can cause systemic venous congestion leading to fluid retention and subsequent pleural effusion, ascites and peripheral edema. Understanding the mechanisms of fluid retention and increased resistance to pulmonary blood flow can potentially lead to more specific and safer therapies. We hypothesize that in pediatric patients who have undergone total cavopulmonary connection, the levels of natriuretic peptides will be significantly altered postoperatively. The changes in these hormone levels can have either a beneficial or detrimental effect, depending on their mechanism of action and relative concentrations, and the patient's hemodynamic status post total cavopulmonary connection. Measuring the levels of ANP, BNP, and ET-1 and correlating these levels to clinical outcomes such as Fontan failure, prolonged chest tube drainage and congestive heart failure, may enable us to predict those patients who are at increased risk and in which more aggressive medical therapy will need to be used. Potential therapy can be tailored based on the changes in specific hormones and their effects after surgery.

In addition to identifying patients at risk early after surgery, these peptide hormone levels may provide prognostic information for late outcome thereby allowing earlier intervention and timely evaluation for heart transplantation. Finally, knowing that specific significant changes occur after the Fontan operation may eventually allow us to test either recombinant analogs of the natriuretic peptides or receptor antagonists of ET-1 to improve cardiovascular function and hemodynamics with potential improvement in quality of life for those patients with single ventricular physiology.

Patterns of heart-rate variability in infants with a complex congenital heart defect - Principal investigator, Jill Winters, RN, PhD, associate professor, Marquette University.

Feeding and growth often are poor for babies who are born with a complex congenital heart defect. A baby's feeding and growth may be related to how the autonomic nervous system (ANS) responds to internal and external conditions and events. The ANS response is marked by variation in the interval between heart beats, called heart rate variability (HRV). HRV may be a physiologic indicator of a baby's regulation of stimuli and response to conditions such as feeding, being awake and alert when not feeding and sleeping. Little is known, however, about HRV for infants with a complex congenital heart defect, how various internal and external conditions affect HRV and its pattern of change or stability through the first year of life.

The purpose of this study is to explore the caregiving experience and behavior during feeding for mothers of babies who are born with a complex congenital heart defect and to examine the HRV of the babies through the first year of life. Forty-six infants with a complex congenital heart defect and their mothers will participate.

The mother's caregiving experience, the infant's HRV, the feeding behavior of mothers and infants and the infant's growth will be assessed in the baby's home at 1, 4, 8 and 12 months of age. HRV will be measured with Holter recorder data collected in four conditions (before, during and after a feeding and during sleep). Mothers and babies will be videotaped during feeding. Mothers will be interviewed about their own and the infant's feeding experience. They also will be interviewed in depth about their caregiving experience, family experience, health-care system experience and their perspective of quality of life for themselves, the family and the baby. Measures of weight, length and head circumference will be obtained and a developmental screening assessment will be done at each home visit. Mothers will complete questionnaires about the impact of the baby's heart defect on the family, symptoms of depression the mother experiences and the baby's temperament. Mothers will be contacted by telephone every two weeks to learn about changes for the family and baby, including illnesses.

Qualitative analysis will be used to learn about the mother's caregiving experience in general and feeding experience in particular. The level of HRV in each of the four conditions and across the four data collection points will be examined. At each age, the relationship of HRV with mother and infant feeding behavior and with growth measures will be explored.

This 2-year study will provide information needed to design a trial of a clinical intervention to support mothers' caregiving competencies and the physiologic regulation of babies with complex congenital heart disease.

New pediatric cardiologist joins staff

Michael Earing, MD, joined Herma Heart Center as a pediatric cardiologist in July 2004. He also is an assistant professor of Pediatrics (Cardiology) at the Medical College of Wisconsin.

Earing attended medical school at Rush Medical College in Chicago. He also completed a residency in Pediatrics and Medicine at Rush Presbyterian St. Luke's Medical Center in Chicago. Earing completed a fellowship in Pediatric Cardiology at the Mayo Clinic Graduate School of Medicine in Rochester, Minn. He is certified in Internal Medicine and Pediatrics and has a special interest in adults with congenital heart disease, pediatric cardiology and echocardiography.