Impact of oxygenator selection on hemodynamic energy indicators under pulsatile and nonpulsatile flow in a neonatal extracorporeal life support model

This study compared the quality of perfusion delivered by two oxygenators--the hollow-fiber membrane Capiox Baby RX05 and silicone membrane Medtronic 0800--using hemodynamic energy indicators. The oxygenators were tested across varying flow rates and perfusion modes in a neonatal extracorporeal life support (ECLS) model. The experimental ECLS circuit included a Jostra HL-20 heart/lung machine with Jostra Roller pump, oxygenators with associated tubing and components, and a neonatal pseudo-patient. We used a 40/60 glycerin/water solution in the circuit as a blood analog. Testing occurred at flow rates of 250, 500, and 750 mL/min at 37°C under both pulsatile and nonpulsatile flow conditions. Hemodynamic data points consisted of recording 20-s intervals of data, and a total of 96 experimental repetitions were conducted. The pressure drop across the Capiox Baby RX05 oxygenator was significantly lower than the pressure drop across the Medtronic 0800 at all flow rates and perfusion modes. Furthermore, the Medtronic 0800 oxygenator showed significantly lower post-oxygenator energy equivalent pressures, total hemodynamic energy values, and surplus hemodynamic energy retention values compared to those of the Capiox Baby RX05. These results indicate the Medtronic 0800 oxygenator significantly dampens the hemodynamic energy compared to the Capiox Baby RX05. Consequently, clinical use of the Medtronic 0800 in a pulsatile ECLS setting is likely to mitigate the benefits provided by pulsatile flow. In contrast, the Capiox Baby RX05 better transmits hemodynamic energy to the patient with much lower pressure drop.     

In-vitro quantification of gaseous microemboli in two extracorporeal life support circuits

During the course of extracorporeal membrane oxygenation, patients are at constant risk of exposure to air emboli. Air emboli may enter the circuit during routine lab sampling, medication administration, air entrainment through the venous cannula, or via a circuit disruption. Circuit components have been designed and positioned to minimize the quantity of air that travels through the arterial line to the patient. The purpose of this study was to assess the air handling of a newer generation extracorporeal life support circuit. The extracorporeal life support circuit consisted of an open hard-shell venous reservoir, Better Bladder (BB14) or silicone bladder (R-14), and Quadrox D oxygenator or 0800 silicone oxygenator. Air emboli detection sensors were placed in the extracorporeal life support circuit: post bladder, post oxygenator, and post heat exchanger if applicable.Air was injected as a 1 mL/min for 5 minutes injection or as a single 5 mL bolus. Emboli detection was recorded continuously during and for 3 minutes post air injection at two blood flow rates (Qb) (.5 and 1.2 L/min). All tests were performed in triplicate with each condition. All tested components reduced the embolic volume transmitted through the circuit. The quantity of this reduction was dependent on both the Qb and the air injection condition. During this in-vitro testing, air emboli passing through any of the components tested was decreased. Furthermore, the emboli delivery was reduced post component with the slower Qb (.5 L/min).     

Comparison of left ventricular unloading strategies on venoarterial extracorporeal life support

OBJECTIVESOur goal was to compare the haemodynamic effects of different mechanical left ventricular (LV) unloading strategies and clinical outcomes in patients with refractory cardiogenic shock supported with venoarterial extracorporeal membrane oxygenation (VA-ECMO).Open in a separate windowMETHODSA total of 448 patients supported with VA-ECMO for refractory cardiogenic shock between 1 March 2015 and 31 January 2020 were included and analysed in a single-centre, retrospective case–control study. Fifty-three patients (11.8%) on VA-ECMO required LV unloading. Percutaneous balloon atrial septostomy (PBAS), intra-aortic balloon pump (IABP) and transapical LV vent (TALVV) strategies were compared with regards to the composite rate of death, procedure-related complications and neurological complications. The secondary outcomes were reduced pulmonary capillary wedge pressure, pulmonary artery pressure, central venous pressure, left atrial diameter and resolution of pulmonary oedema on a chest X-ray within 48 h.RESULTSNo death related to the LV unloading procedure was detected. Reduction in pulmonary capillary wedge pressure was highest with the TALVV technique (17.2 ± 2.1 mmHg; P < 0.001) and was higher in the PBAS than in the IABP group; the difference was significant (9.6 ± 2.5 and 3.9 ± 1.3, respectively; P = 0.001). Reduction in central venous pressure with TALVV was highest with the other procedures (7.4 ± 1.1 mmHg; P < 0.001). However, procedure-related complications were significantly higher with TALVV compared to the PBAS and IABP groups (50% vs 17.6% and 10%, respectively; P = 0.015). We observed no significant differences in mortality or neurological complications between the groups.CONCLUSIONSOur results suggest that TALVV was the most effective method for LV unloading compared with PBAS and IABP for VA-ECMO support but was associated with complications. Efficient LV unloading may not improve survival.     

Novel multi-functional life support system

Concepts of cardiopulmonary support (CPS), extracorporeal membrane oxygenation (ECMO), and ventricular support (VS) have been thoroughly studied and refined. These perfusion adjuncts often require multiple devices, skill sets, and significant financial burden to purchase, maintain, deploy, and use. We describe a novel system that is rapidly deployable, user-friendly, portable, safe, and economical. Over a 1-year period we have used a multi-functional life support system (MLS) in the cardiac catheterization laboratory, cardiovascular intensive care unit, and cardiac surgical suites. Further, we have conducted multiple transports within the hospital and one to an alternate facility. Applications have included ECMO, cardiopulmonary resuscitation-supported cardiogenic shock, high risk percutaneous coronary intervention (PCI), valvuloplasty, right ventricular assist device transition to ECMO post cardiotomy, left ventricular assist device transition to ECMO, ventricular septal defect closure, and ECMO transition to conventional cardiopulmonary bypass (CPB). Duration of support has ranged from approximately 39 minutes to several days. Keywords: extracorporeal membrane oxygenation (ECMO), percutaneous ventricular assist device, cardiopulmonary support, portable cardiopulmonary life support, ventricular assist.     

Outcomes in patients requiring repeat extracorporeal membrane oxygenation

Background

As the number of patients requiring extracorporeal membrane oxygenation (ECMO) increases nationwide, many patients may require ECMO more than once. We review our experience and outcomes in patients requiring repeat ECMO support.

Methods

The Nebraska ECMO Research Database was utilized for data analysis, and repeat ECMO patients (REPs) were compared to the overall ECMO population.

Results

Of 246 patients, 2.4% (6/246) were REPs. There was no statistical difference between the median days of initial support run (P = 0.670) and second support run (P = 0.813) for REPs when comparing to the non‐REP population. Median hospital length of stay for REPs was 53 days (16‐124) compared to the non‐REPs, who had a median hospital length of stay of 22 days (1‐270); P = 0.043. In‐hospital mortality rate for REPs was 50% (3/6) and 50% for non‐REPs (120/240). Survival 30 days postdischarge for REPs was 50% (3/6) compared to non‐REPs at 48.3% (116/240); P = NS.

Conclusions

Outcomes for repeat ECMO patients compare favorably to the overall ECMO population and suggest a need to explore and broaden the clinical indications for repeat ECMO.     

Kidney transplantation on extracorporeal life support for primary cardiac allograft dysfunction

Patients undergoing heart-kidney transplants who have primary graft dysfunction (PGD) of the heart are at risk of losing both organs, which may cause reluctance on the part of the transplant team to proceed with transplanting the kidney while the transplanted heart is being supported by mechanical device. We describe a case series in which 2 patients received kidney transplants while on veno-arterial ECMO support for PGD after heart transplant. Both patients are alive more than 1 year following transplant, with good cardiac and renal function and no signs of cardiac rejection. Kidney transplant surgery is safe for patients on veno-arterial ECMO support for cardiac PGD. It allows the heart recipient to receive a kidney from the same donor with both immunologic and survival advantages.     

Outcomes of congenital heart surgery patients after extracorporeal life support at Texas Children's Hospital

The objective of this study was to investigate the outcomes of children with heart failure of various etiologies requiring temporary use of currently available technology in the U.S.A. after extracorporeal life support (ECLS) [left ventricular assist device (LVAD) or extracorporeal membrane oxygenation (ECMO)] at Texas Children's Hospital. Between July of 1995 and October of 2002, 2847 patients underwent congenital heart surgical repairs with the aid of cardiopulmonary bypass at Texas Children's Hospital. During this period, 17 patients required chronic mechanical circulatory assistance with Biomedicus centrifugal pump (n=8) or Thoratec LVAD (n=4), and ECMO (n=5). Six out of 17 patients required ECLS for postcardiotomy heart failure. Seven of the 17 patients had congenital heart disease, six had cardiomyopathy, three had late acute rejection following heart transplantation, and one had myocardial infarction. Twelve patients survived and five patients expired. Six of 12 survivors recovered sufficient cardiac function to allow device removal; and the remaining six patients underwent heart transplantation. Three out of five deaths were ECMO patients. The need for ECLS following repair of congenital heart disease is extremely rare in our institution. The requirement for the use of ECMO confers a significantly higher mortality presumably because of associated combined cardiopulmonary failure. Congenital heart disease appears to be associated with significantly higher mortality.     

Bloodless extracorporeal membrane oxygenation in the Jehovah's Witness patient

The successful use of prolonged extracorporeal life support with a heart-lung machine was first performed in 1972, as described by Hill et al., on a young man with post-traumatic respiratory failure. The first successful use of extracorporeal membrane oxygenation (ECMO) was 1976 by Bartlett et al. Since this time, the use of ECMO for neonatal and pediatric pulmonary support has become a standard of care in many children's hospitals. The use of ECMO, being a very invasive procedure, is not without risk. In our experience, most patients require multiple transfusions of the different blood components (packed red blood cells, plasma, platelets, and cryoprecipitate). Exposure to one or more blood products often occurs with connection to the ECMO circuit, as the circuit is generally primed with blood products or whole blood. Jehovah's Witnesses (JWs) are known best in the medical community for their refusal of blood products, even at the risk of death, which presents challenges for health care providers. This belief stems from the biblical passages that have been quoted as forbidding transfusion: Genesis 9:3-4, Leviticus 17:13-14, and Acts 15:19-21. This refusal of blood poses even greater challenges when treating the pediatric JW population. When a blood product is deemed medically necessary for the JW patient, the healthcare provider must either seek legal intervention, or support the patient's/family's wishes and associated outcome. This ethical dilemma may be further complicated in the setting of therapies, which may pose additional risks and potentially less clear benefit such as with ECMO. Bloodless cardiac surgery with cardiopulmonary bypass has been reported in the JW population in adults and pediatrics, including neonates. After a thorough search of the literature, no published report of a JW patient being supported on ECMO without blood or blood component utilization was identified. This case report will present our experience with multiple day, bloodless ECMO support of a 17-year-old male patient of the JW faith.     

Venovenous versus venoarterial extracorporeal membrane oxygenation in congenital diaphragmatic hernia

Background: Extracorporeal membrane oxygenation (ECMO) has a significant role as a final rescue modality in severe respiratory failure of the newborn with congenital diaphragmatic hernia (CDH). The objective of this study was to compare the efficiency of venovenous (VV) versus venoarterial (VA) ECMO in newborns with CDH.Methods: A retrospective report of 11 years experience (1990 through 2001) of a single center, comparing VV and VA ECMO is given. VV ECMO was the preferred rescue modality for respiratory failure unresponsive to maximal medical therapy. Only when the placement of a VV ECMO 14F catheter was not possible, VA ECMO was used. Forty-six patients met ECMO criteria; 26 were treated with VV ECMO and 19 with VA ECMO. One patient underwent conversion from VV to VA ECMO.Results: Before ECMO, there was no difference between VV and VA ECMO patients in mean oxygenation index (83 v 83), mean airway pressure (18.4 v 18.9 cm H₂O), ECMO cannulation age (28 v 20 hours), or in the percentage of patients who needed dopamine and dobutamine (100% v 100%). From November 1994, nitric oxide (NO) was available; before ECMO, 11 of 14 (79%) VV ECMO patients received NO versus 9 of 10 (90%) patients in the VA group. VV ECMO patients were larger (3.34 v 2.77 kg; P < .05) and of advanced gestational age (39.0 v 36.9 wk; P < .05) compared with VA ECMO patients. There was no significant difference between VV and VA ECMO patients in survival rate (18 of 26, 69% v 13 of 19, 68%), ECMO duration (152 v 150 hours), time of extubation (32.0 v 33.5 days), age at discharge (73 v 81 days), or incidence of short-term intracranial complications (3.8% v 10.5%) or myocardial stun (3.8% v 15.8%).Conclusions: The authors conclude that VV ECMO is as reliable as VA ECMO in newborns with CDH in severe respiratory failure who need ECMO support and who can accommodate the VV double-lumen catheter. Because of its potential advantages, VV ECMO may be the preferred ECMO method in these infants.     

Rescue extracorporeal life support for acute verapamil and propranolol toxicity in a neonate

Extracorporeal life support (ECLS) to manage acute antiarrhythmic drugs toxicity in neonates has never been reported. Here presented is a case of venoarterial extracorporeal membrane oxygenation support in a newborn with refractory low cardiac output as a result of acute Ca-channel and β-receptor antagonist toxicity for treatment of paroxysmal supraventricular tachycardia (SVT). Shortly after onset of ECLS, the baby recovered sinus rhythm and subsequent bouts of SVT were controlled by amiodarone infusion and repeated DC shocks. Weaning was possible on the 5th day after implant, once recovery of the left ventricular function and optimization of the antiarrhythmic medication were achieved. In neonates with severe but potentially reversible cardiac dysfunction caused by drug toxicity, ECLS can maintain cardiac output and vital organ perfusion while allowing time for drug redistribution, metabolism, and clearance.     

2004 survey of ECMO in the neonate after open heart surgery: circuitry and team roles

Over the past 20 years, the bulk of the literature and texts published about extracorporeal membrane oxygenation (ECMO) has been written by physicians and nurses. The consensus of this body of printed information would suggest, among other things, that (1) despite significant advancements in extracorporeal technology, the standard ECMO circuit has remained fundamentally unchanged since originally described in 1982, and (2) perfusionists are nearly absent from the staffing algorithm at most centers. While these conclusions may be representative of the extracorporeal life support (ELSO) reporting centers, they may not be representative of the field as a whole. We hypothesized that the use of modern extracorporeal equipment and the involvement of perfusionists in ECMO patient care is largely underreported in previous studies. To study this hypothesis, we developed a standard survey instrument and queried perfusion teams from the hospitals listed on the American Society of Extra-Corporeal Technology Pediatric Registry. All centers were contacted by phone and were asked questions regarding their caseload, circuitry, and staffing algorithms. Data are reported as a percentage of respondents. ECMO is used as a method of mechanical support after neonatal open heart surgery in 94% of centers surveyed. For 60% of the centers, a silicone membrane oxygenator is used exclusively, whereas 40% of the centers have used a hollow fiber oxygenator (HFO), and of that group, 19% use a HFO routinely for neonatal post-cardiopulmonary bypass ECMO. Roller pumps are used exclusively at 65% of the centers, whereas centrifugal pumps are used routinely in 12%, and 23% have used both. Perfusionists are responsible for set-up/initiation (79%) and daily rounding/troubleshooting (71%), and provide around-the-clock bedside care (46%) at the surveyed centers. These data suggest that previously published ELSO-centric ECMO studies may significantly underestimate the contemporary application of modern technologies and the involvement of perfusionists.     

Extracorporeal life support during and after bilateral sequential lung transplantation in patients with pulmonary artery hypertension

The use of extracorporeal membrane oxygenator instead of standard cardiopulmonary bypass during lung transplantation is debatable. Moreover, recently, the concept of prolonged postoperative extracorporeal membrane oxygenator (ECMO) support has been introduced in many transplant centers to prevent primary graft dysfunction (PGD) and improve early and long-term results. The objective of this study was to review the results of our extracorporeal life support strategy during and after bilateral sequential lung transplantation (BSLT) for pulmonary artery hypertension. We review retrospectively our experience in BSLT for pulmonary artery hypertension between January 2010 and August 2018. A total of 38 patients were identified. Nine patients were transplanted using cardiopulmonary bypass (CPB), in eight cases CPB was followed by a prolonged ECMO (pECMO) support, 14 patients were transplanted on central ECMO support, and seven patients were transplanted with central ECMO support followed by a pECMO assistance. The effects of different support strategies were evaluated, in particular in-hospital morbidity, mortality, incidence of PGD, and long-term follow-up. The use of CPB was associated with poor postoperative results and worse long-term survival compared with ECMO-supported patients. Predictive preoperative factors for the need of intraoperative CPB instead of ECMO were identified. The pECMO strategy had a favorable effect to mitigate postoperative morbidity and mortality, not only in intraoperative ECMO-supported patients, but even in CPB-supported cases. In our experience, ECMO may be considered as the first choice circulatory support for lung transplantation. Sometimes, in very complex cases, CBP is still necessary. The pECMO strategy is very effective to reduce incidence of PGD even in CPB-supported patients.     

Application of a pressure-relieving air compliance chamber in a single-pulsatile extracorporeal life support system: an experimental study

Nonpulsatile blood pumps are mainly used in extracorporeal life support systems. Although pulsating blood flow is known to be physiological, a pulsatile pump is not commonly applied in a circuit with a membrane oxygenator because of damage to the blood cells. The hypothesis that the placement of a pressure-relieving compliance chamber in a circuit might reduce blood cell trauma was tested. An extracorporeal life support circuit was constructed in an acute lung injury model of dogs by oleic acid infusion. The animals were divided into three groups. In group I (n = 6) a nonpulsatile centrifugal pump was used as a control. In group II (n = 4) a single-pulsatile pump was used, and in group III (n = 6) a single-pulsatile pump equipped with a compliance chamber was used. Pump flow was maintained at 1.8-2.0 L/min for 2 h. Hemodynamics and blood gas analyses indicated that the pulsatile groups II and III had better results than the nonpulsatile group I. The plasma-free hemoglobin level, which indicates blood cell trauma, was the lowest in group I and the highest in group II but was significantly decreased in group III. A pressure-relieving compliance chamber could significantly reduce high circuit pressures and blood cell trauma.