Robert K. Wise

Current Techniques and Outcomes in Extracorporeal Life Support

For patients with catastrophic cardiac or pulmonary failure, extracorporeal life support (ECLS) often represents the last line of defense against impending and near-certain demise. Recent increases in the application of this technology for adult support have contributed to the continued growth of ECLS utilization in the USA and around the world. With widened application, there is increased clinical demand for this expensive yet potentially life-saving technology. For scientists and clinicians working in the field, there is an obligation to pursue the continued refinement of ECLS technology, all with the goal of improving patient survival and subsequent quality of life. As ECLS becomes more common, providers will be challenged to be judicious in the selection of both the most appropriate patients for ECLS as well as the most appropriate equipment. In this report, we aim to review current ECLS use and outcomes, both nationally and at our center, and to describe our recent and future translational research projects intended to elevate ECLS circuitry.

Successful treatment of peripartum cardiomyopathy with extracorporeal membrane oxygenation

A 24-year-old female developed heart failure within four months of delivering her first child. Echocardiogram revealed a moderately dilated left ventricle with severely reduced systolic function. She continued to decompensate, requiring intubation and inotropic support. When the use of an intra-aortic balloon pump failed to stabilize the patient, the decision was made to place her on ECMO. The circuit consisted of a Quadrox D membrane oxygenator and a CentriMag® centrifugal pump. After 11 days of support, the patient met the weaning criteria and was successfully removed from ECMO. She was discharged one month after her admission. The new technology available allows for ECMO to be considered as an earlier option for the treatment and management of these patients as a bridge to recovery.

Pericardium as a thoracic aortic patch: Glutaraldehyde-fixed and fresh autologous pericardium

The repair of complex coarctation of the aorta often requires an aortic patch. Prosthetic patches lack growth potential and are associated with an increased incidence of aneurysm formation opposite the patch. We compared buffered glutaraldehyde-fixed patches, used in six animals (group 1), and untreated autologous pericardial aortic patches, used in five animals (group 2). Weanling pigs underwent pericardial patch replacement of a 1 X 2-cm diamond-shaped segment of the lateral wall of the descending thoracic aorta at the level of the aortic isthmus. Six months following patch aortoplasty, the animals were killed and the in situ patch dimensions were measured and compared to the measurements obtained at implantation. The increases in length, recorded as mean percentage change +/- SEM, were 34.7 +/- 3.7% for group 1 and 102.8 +/- 20.3% for group 2 animals; the increases in width were 91.4 +/- 31.7% for group 1 and 192.4 +/- 31.4% for group 2. The percentage changes for both length and width were significantly different between groups (P less than 0.05). Pull strength testing of standard-size patch samples demonstrated no significant difference in tensile breaking load between groups: group 1 = 959 +/- 277 g, group 2 = 795 +/- 86 g. Thoracic aortography revealed no evidence of stenosis or aneurysmal dilation in either group. Autologous pericardium is resilient, strong, and readily available and has expansile potential that makes it an ideal aortic patch material. We conclude that glutaraldehyde fixation does not provide additional strength and limits graft expansile potential when compared to untreated pericardium.

Translational Research in Pediatric Extracorporeal Life Support Systems and Cardiopulmonary Bypass Procedures: 2011 Update

Over the past 6 years at Penn State Hershey, we have established the pediatric cardiovascular research center with a multidisciplinary research team with the goal to improve the outcomes for children undergoing cardiac surgery with cardiopulmonary bypass (CPB) and extracorporeal life support (ECLS). Due to the variety of commercially available pediatric CPB and ECLS devices, both in vitro and in vivo translational research have been conducted to achieve the optimal choice for our patients. By now, every component being used in our clinical settings in Penn State Hershey has been selected based on the results of our translational research. The objective of this review is to summarize our translational research in Penn State Hershey Pediatric Cardiovascular Research Center and to share the latest results with all the interested centers.

Benefits of pulsatile flow in pediatric cardiopulmonary bypass procedures: from conception to conduction

This review on the benefits of pulsatile flow includes not only experimental and clinical data, but also attempts to further illuminate the major factors as to why this debate has continued during the past 55 years. Every single component of the cardiopulmonary bypass (CPB) circuitry is equally important for generating adequate quality of pulsatility, not only the pump. Therefore, translational research is a necessity to select the best components for the circuit. Generation of pulsatile flow depends on an energy gradient; precise quantification in terms of hemodynamic energy levels is, therefore, a necessity, not an option. Comparisons between perfusion modes should be done after these basic steps have been taken. We have also included experimental and clinical data for direct comparisons between the perfusion modes. In addition, we included several suggestions for future clinical trials for other interested investigators.

Impact of the 2013/2014 influenza season on extracorporeal membrane oxygenation programs in the United States.

When looking back at the 2013–2014 influenza season, our impressions were that it seemed busier in terms of patients requiring extracorporeal membrane oxygenation (ECMO) than the 2012–2013 season. More patients were placed on veno-venous ECMO for respiratory failure, and the early to middle-aged adults (18–64 years) seemed to be hit the hardest. We decided to compare the data for both seasons to see if our impressions were real. Even though the Centers for Disease Control and Prevention (CDC) considers September through the end of April as the influenza season, we compared from the beginning of November through March, because that is when our activity levels changed. At our institution, we employ centrifugal pumps for our pediatric and adult ECMO circuits. The circuit is comprised of a Bioline-coated Quadrox-D membrane oxygenator (MAQUET Cardiopulmonary AG, Hirrlingen, Germany), centrifugal pump (CentriMag, Levitronix LLC, Waltham, MA, USA; Rotaflow, MAQUET Cardiopulmonary AG; or CARDIOHELP System, MAQUET Cardiopulmonary AG), and coated 1/4′′ or 3/8′′ PVC tubing (Fig. 1). The circuit was primed with 250 or 450 mL of Plasmalyte A depending on the size of the circuit.

The effects of haemofiltration on cefazolin levels during cardiopulmonary bypass

Ultrafiltration has been shown to affect cardiac drug concentrations during cardiopulmonary bypass (CPB), based on their respective pharmacological properties. In an attempt to understand the aetiology of sternal wound infections, a study was performed to eliminate the use of ultrafiltration as a possible cause. We compared cefazolin levels at three time intervals during the course of routine CPB with ultrafiltration to those levels in a control group in which ultrafiltration was not used. Our results indicate that there is little difference in the rate of decay of antibiotic levels with or without the use of a haemoconcentrator. This implies that ultrafiltration procedures do not put the patient at any increased risk for infection and that additional measures beyond that which we would normally use at our institution need not be taken.

The new role of the perfusionist in adult extracorporeal life support

Adult and pediatric extracorporeal life support (ECLS) has been transformed by the European1 and Australian 2 experiences with a reduction of the circuit to its most basic form (Figure 1). Many factors have converged at this point in time to allow us to offer this support. The availability in the U.S.A. of an advanced oxygenator (QuadroxD) (Maquet Inc., Bridgewater, NJ), long-term centrifugal pumps and circuit coatings offers us the means to provide ECLS. The other equally important factor is the intensivist trained in extracorporeal therapies. Once the intensive care unit registered nurse (ICU RN) is trained to safely and effectively manage both the patient and ECLS circuit, this support may be offered. The perfusionist is in an unique position to educate and mentor the ICU RN in ECLS. There is, perhaps, no one in a better position to explain this equipment and its uses in an interdisciplinary-oriented pediatric and adult ECLS program than a perfusionist.

Impact of Translational Research on Optimization of Neonatal Cardiopulmonary Bypass Circuits and Techniques-The Penn State Health Approach.

Translational research is a “bench-to-bedside and beyond” approach which transforms scientific discoveries during engineering and basic science research in the laboratory and preclinical studies into clinical applications to improve the quality of healthcare. The goal of translational research is to provide scientific evidence for decision-making on actions to improve health. The experimental design, conduct, analysis, and conclusion of the study must strictly follow the scientific method. More importantly, experiments must have the ability to be duplicated. Additionally, translational research must be conducted at independent institutions without financial incentive or other personal benefit from the projects. Therefore, regarding the selection of components of cardiopulmonary bypass (CPB) circuitry, translational research is mandatory, not optional, both for the safety of neonatal and pediatric cardiac patients undergoing CPB procedures as well as for saving the institutional resources. Over the past 13 years at Penn State Health Children’s Hospital and College of Medicine, our multi-disciplinary research team has established the Pediatric Cardiovascular Research Center with the goal of improving the outcomes for children undergoing cardiac surgery with CPB procedures. Currently, every CPB component used in our clinical setting at Penn State Health has been selected based on the results of our translational research projects. This editorial will summarize these translational research projects for neonatal CPB patients in the Penn State Health Pediatric Cardiovascular Research Center and will share the latest results with all interested readers.

Unique static discharge events on two CentriMag® (2nd Gen) ECMO patients causing console failure:

The use of ECMO for cardiovascular support continues to increase in the United States and around the world. It is not a benign endeavor as serious complications may occur. We present our experience of two second generation CentriMag® (Abbott formerly Thoratec Inc.) console failures that occurred while transporting the patients to other areas of the hospital. In each incident, the patients were immediately placed on back-up units and the transport continued. No patient complications could be attributed to the failures. An investigation by Abbott engineers traced the failure to a static build-up and discharge caused by a non-manufacturer-approved metal rod that was utilized to mount the external monitor. The static discharge caused a disruption of electrical continuity between the control system and the motor, stopping the motor as well as the monitoring system. Removal of the mounting rod prevented replication of the situation in the lab. We have removed the rod from our clinical units and have not experienced any other pump failures.