Transporte interhospitalario con membrana de oxigenación extracorpórea: cuestiones a resolver / Issues to resolve with the use of extracorporeal membrane oxygenation during interfacility transportation

El soporte extracorpóreo con membrana de oxigenación extracorpórea (ECMO) está indicado en pacientes resistentes al tratamiento, con shock cardiogénico o insuficiencia respiratoria y en aquellos pacientes reagudizados subsidiarios de trasplante cardiaco y pulmonar. La experiencia profesional y la cantidad de recursos necesarios son causas por las que se cree que la regionalización podría beneficiar a este tipo de pacientes a través del establecimiento de centros de referencia en ECMO y de la integración de una red de transporte especializado en ECMO. Debido a su mayor complejidad, este tipo de transporte supone un reto para los sistemas sanitarios y para los propios médicos, y requiere un abordaje multidisciplinar e interterritorial. El transporte en ECMO es más seguro que sin soporte mecánico, sin existir por el momento criterios de iniciación de la terapia en pacientes a trasladar, pudiendo ser necesarios criterios de menor gravedad en ellos. La formación y la especialización del equipo tanto en terapias de soporte extracorpóreo como en transporte interhospitalario, así como la sistematización de los traslados, pueden favorecer los resultados. No existen estudios acerca de las condiciones que deben cumplir los medios de transporte, siendo el espacio y la estabilidad características importantes. El traslado aéreo en ECMO supone una posibilidad cada vez más frecuente, existiendo datos sobre su seguridad, pero no sobre la fisiología del paciente en ECMO en altura, lo cual podría ayudar a la indicación y gestión de este tipo de transporte

Extracorporeal membrane oxygenation (ECMO) support is indicated in patients who are refractory to treatment, those with cardiogenic shock or respiratory failure and those with exacerbations eligible for heart and lung transplantation. Physician experience and quantity of necessary resources are reasons why regionalization could benefit patients of this kind, establishing ECMO reference centers and integrating a transportation network specialized in ECMO. This type of transportation is a challenge for healthcare systems and physicians, given its greater complexity, requiring a multidisciplinary and inter-territorial approach. ECMO transportation is safer than without mechanical support, though there are currently no criteria for starting such therapy in patients being transferred. Criteria of lesser severity might be necessary for these patients. The training and specialization of the team in extracorporeal support therapies, interfacility transport and the systemization of transfer can improve the outcomes. There are no studies on the conditions that must be met by the transportation media, although space and stability are important characteristics. Air transfer with ECMO is an increasingly frequent option. Although there are data on its safety, there are none on the physiology of patients undergoing ECMO at high altitudes. Such information could be of help in the indication and management of this type of transportation

Temporal trends of survival and utilization of mechanical circulatory support devices in patients with in-hospital cardiac arrest secondary to ventricular tachycardia/ventricular fibrillation.

BACKGROUND: Pulseless ventricular tachycardia/ventricular fibrillation (VT/VF) is the initial rhythm in a third of in-hospital cardiac arrest patients. Mechanical circulatory support (MCS) device use remains poorly understood in this population. METHODS: We conducted an observational analysis of temporal trends in the utilization of MCS in VT/VF IHCA between January 2008 and December 2014 utilizing the Nationwide Inpatient Sample (NIS) database. Using multivariable analysis, we assessed factors associated with MCS use and survival to discharge. RESULTS: Among 151,628 hospitalizations with VT/VF IHCA, 14,981 (9.9%) received MCS. Intra-aortic balloon pump (IABP) was the most commonly used MCS (9.1%). From 2008 to 2014, there was significant increase in the utilization of MCS (8.7-11%; ptrend < 0.0001). On multivariable analysis, there was 12-fold increase and three-fold increase in the utilization of PVAD and ECMO respectively; however, there was no significant change in the use of IABP. Over the seven-year sample period, there was significant increase in the overall survival to hospital discharge (35.4-43.5%; ptrend < 0.0001). Survival to hospital discharge increased in both MCS and non-MCS groups. CONCLUSION: There was significant increase in utilization of MCS after VT/VF IHCA during the study period. IABP was the most commonly utilized MCS. The survival to hospital discharge increased in the overall study population including both MCS and non-MCS groups. Future studies are needed to identify patient population most likely to benefit from the use of MCS after VT/VF IHCA.

Oxigenador de membrana extracorpóreo en 12 casos de shock cardiogénico tras cirugía cardiaca / Extracorporeal membrane oxygenation after cardiac surgery in 12 patients

Objetivos: La aparición de un shock cardiogénico postcardiotomía con imposibilidad de desconexión de la circulación extracorpórea y/o el desarrollo de bajo gasto postoperatorio refractario a los fármacos vasoactivos y balón de contrapulsación, conlleva alta mortalidad. El oxigenador de membrana extracorpóreo (ECMO) es un sistema de asistencia circulatoria temporal que proporciona un apoyo hemodinámico y respiratorio al paciente en situación de shock cardiogénico para evitar el desarrollo consecuente de fallo multiorgánico y muerte. Material y métodos: Se recogieron de manera retrospectiva todos los casos que fueron tratados con ECMO tras la puesta en marcha de la unidad de asistencia circulatoria en nuestro hospital. Se registraron datos demográficos, indicación, valoración Euroscore de los pacientes, duración de la asistencia, complicaciones y supervivencia. Resultados: En los primeros tres años de funcionamiento, de un total de 1.375 intervenciones de cirugía cardiaca se colocó el sistema ECMO en 12 pacientes (0,87%) postquirúrgicos, 8 postcardiotomía en cirugía cardiaca y 4 tras fallo primario del injerto postrasplante cardiaco. La media de edad fue de 56,8 ± 9,1 años, el porcentaje previsto de mortalidad calculado por Euroscore de 37,3% ± 16,7%, la duración media de la asistencia de 5,4 ± 2,5 días. Las complicaciones más frecuentes fueron la hemorragia en la zona quirúrgica, el taponamiento y la insuficiencia renal aguda. La mortalidad global intrahospitalaria fue del 50%, inferior a la publicada. Conclusiones: En nuestra serie, el ECMO fue una alternativa real de soporte temporal que proporcionó el tiempo necesario para observar y decidir sobre la viabilidad cardiaca, manteniendo un gasto cardiaco adecuado que redujo la mortalidad en estos pacientes(AU)

Objectives: Mortality is high when cardiogenic shock develops after cardiotomy, making it impossible to discontinue extracorporeal circulation and/or leading to low postoperative cardiac output that is refractory to treatment with vasoactive drugs or implantation of an intra-aortic balloon pump. Extracorporeal membrane oxygenation (ECMO) provides temporary assisted circulation, lending hemodynamic and respiratory support to the patient with cardiogenic shock in order to prevent multiple organ failure and death. Material and methods: For this retrospective study of cases in which ECMO was applied in our hospital’s assisted circulation unit, we analyzed demographic data, indication, score on the European system for cardiac operative risk evaluation (Euroscore), duration of assistance, complications, and survival. Results: In the first 3 years after the assisted circulation unit was established, during which 1375 cardiac interventions took place, ECMO was used postoperatively in 12 patients (0.87%). In 8 of the patients, assistance was provided during cardiac surgery following cardiotomy and in 4 transplant patients it was used following primary graft failure. The mean (SD) patient age was 56.8 (9.1) years. The Euroscore predicted 37.3% (16.7%) of the deaths. ECMO was used for a mean of 5.4 (2.5) days. The most frequent complications were bleeding in the surgical area, cardiac tamponade, and acute renal insufficiency. Overall in-hospital mortality was 50%, lower than rates reported in the literature. Conclusions: ECMO provided viable temporary support, maintaining adequate cardiac output while the patient’s condition could be observed and heart function evaluated. Mortality was reduced(AU)

[Current state and development of artificial lungs].

The artificial lung is a technical device for providing life support; it will be put in use when the natural lungs are failing and are not able to maintain sufficient oxygenation of the body's organ systems. From the viewpoint of long-term development, the artificial lung should be permanently implanted in the body, so that it will substitute for the human pulmonary function partially or completely. In this paper, four artificial lung technologies were expounded with reference to the development and research process of artificial lung. They were extracorporeal membrane oxygenation, intravascular artificial lung, implantable artificial lung, and pumpless extracorporeal lung assist. In this paper were described the structure of the four kinds of artificial lung, the working principle, and their advantages, disadvantages and indications. The prospect of artificial lung was evaluated in the light of the data from the existing animal experiments and from the clinical experience of the centers.

[The development of research on membrane oxgenator application].

Extra-luminal flow hollow fiber membrane oxygenator (ELFHFMO) has been widely applied in cardiopulmonary bypass (CPB) and extracorporeal membrane oxygenation (ECMO) or extracorporeal life support (ECLS) because of its advantages over other types of MO. But its low hemocompatibility and durability are the major problems in clinical application that even have limited its wide application. In this paper, we reviewed the recent researches on how to improve the hemocompatibility and durability of ELFHFMO.

Compact intra- and extracorporeal oxygenator developments.

For patients with acute lung failure, mechanical ventilation entails the risk of lung tissue damage due to high oxygen pressure and concentration. Membrane oxygenation for one to two weeks can rest the lungs due to decreased ventilation parameters, representing a potential bridge to recovery, but implies the substantial risks of blood damage, plasma leakage and infection, which often have fatal results for patients. At the Helmholtz Institute in Aachen, two types of membrane oxygenators, which aim to overcome previous limits, are under development. Both present compact designs, reduced surface and priming volumes and easier handling. HEXMO is a miniaturized extracorporeal membrane oxygenator. The integration of a small rotary blood pump into the centre of the oxygenator reduces the amount of tubing and connectors in the system. Blood is convectively warmed by the pump motor housing, thus, the use of a heat-exchanger can be avoided. This compact design reduces surface and priming volume and allows better handling, especially in critical situations. A second development is the intravascular oxygenator HIMOX, which is inserted directly into the vena cava. Priming volume and blood contact surface are reduced, as well as infection risk and control needs for the patient. A new cross-flow fibre configuration is used for improving gas transfer within the limited space inside the vena cava. A microaxial blood pump is integrated into the device for compensating the pressure drop across the fibres and allowing venous return and physiological pressure in the organs proximal to the oxygenator.

Preliminary experimental study about the feasibility of combining pulsatile cardiopulmonary support system and a membrane oxygenator.

A cardiopulmonary support (CPS) device that incorporated a pneumatic ventricular assist device (VAD) and a membrane oxygenator was developed for the support of patients with profound heart and/or respiratory failure. This device has an advantage of being both a pulsatile assist device and membrane oxygenator. A "triple flow" regulator was included in this system to control the blood flow through the oxygenator. The purpose of this study was to clarify the efficacy of this system in supporting an animal model with combined cardiac and respiratory failure. In vitro tests showed 3.7 L/min of pump flow under 1.6 L/min of oxygen supply to the oxygenator even though there was a 50% clamp of a "triple flow" regulator with sufficient pulsatility. In 14 acute canine experiments, cardiogenic shock and acute respiratory failure were introduced by coronary ligation and mechanical hypoventilation simultaneously. The pump flow was maintaned at 1.95-0.6 L/min (average 1.2 L/min) and the driving pressure of the pump was controlled between 200 and 300 mmHg positive pressure and -20 to -50 mmHg negative pressure. The driving rate was fixed at 100 bpm and systolic/diastolic ratio was controlled between 35-50%. The canines were divided into control group (n = 4) and pumped group (drained from the right atrium n = 7, drained from the left atrium n = 3). By using CPS system, flow and aortic pressure recovered to the initial baseline level. Without this support, the canine model could not maintain systemic circulation. In the group drained from right atrium, central venous pressure decreased with the device from 13.9 +/- 2.4 to 5.6 +/- 1.4 cm H2O (p < 0.01), returned to the initial level without this device (p < 0.01). In the group drained from left atrium, pulmonary capillary wedge pressure decreased from 37.9 +/- 4.6 to 20.8 +/- 5.7 mmHG (p < 0.01), and returned to the initial level without the device, arterial oxygen tension levels increased tension levels increased (p < 0.01), and also arterial oxygen saturation levels recovered (p < 0.01). The results suggest that the current model of the pulsatile CPS has a potential to support the animal model with combined cardiac and respiratory failure.

[Present status and future observation of membrane oxygenator].

The oxygenator has been developed as the most important tools for open heart surgery as a part of pump-oxygenator. Recently, two kinds of them are routinely selected. One is the bubble oxygenator (BO) and the other is the membrane oxygenator (MO). The latter is recognized as the most physiological and similar to the human lung. It is proved by many researchers that the denaturation of the blood elements is less in the MO compare with the BO even it is used for short period such as open heart surgery. The more hospitals and institutes have been taking more MO than BO. Microporous membrane and dense (silicone) membrane are used for MO. Combination of the both membranes is also considerable now. Hollow fiber (capillary) type MO is getting more than plate or coil type. ECMO (extracorporeal membrane oxygenation) is gradually developed as characteristic application of MO. ECMO is one type of assisted circulation by means of MO and is applied for acute respiratory failure (in original sense) and for acute cardio-respiratory failure (in wide sense). Earlier application for acute respiratory failure of neonate and children should be considered expecting with better results now. Bridge use for heart transplantation would be considered in future.