Extracorporeal membrane oxygenation (ECMO) is an. Mobile Extracorporeal Membrane Oxygenation Unit Expands Cardiac Assist Surgical Programs

Transcription

1 Mobile Extracorporeal Membrane Oxygenation Unit Expands Cardiac Assist Surgical Programs Vlad Gariboldi, MD, Dominique Grisoli, MD, Amine Tarmiz, MD, Nicolas Jaussaud, MD, Virginie Chalvignac, MD, François Kerbaul, MD, PhD, and Frédéric Collart, MD Cardiac Surgery Department, Timone s Adults Hospital, Marseille, France Background. Extracorporeal membrane oxygenation (ECMO) is an effective technique to provide emergency mechanical circulatory or respiratory assistance in critically ill patients. A Mobile Remote Cardiac Assist unit was created to implant ECMO in patients from outside our institution and bring them back in our intensive care unit for follow-up when stabilized. This study was undertaken to evaluate the feasibility and the preliminary results of this procedure. Methods. Between March 2006 and June 2008, 38 consecutive patients with acute cardiac or respiratory failure were implanted with percutaneous ECMO. The logistic concerns, indications, complications, and outcomes of these patients were analyzed. Results. There were no logistic or technical problems during the round trip or ECMO implantation. Mean distance from our intensive care unit was 68 km (1 to 230). Maximal time limit between the phone call and implantation was 90 minutes. The indications were fulminant myocarditis, pharmacologic suicide attempt, acute myocardial infarction, postpartum cardiopathy, end-stage cardiomyopathy, with left ventricular ejection fraction of (n 32), or acute respiratory distress syndrome without cardiac failure (n 6). Patients received a percutaneous venoarterial femoral ECMO with immediate reperfusion of the limb or venovenous ECMO for isolated lung failure. Seventeen patients (45%) were successfully weaned from ECMO after days. Four patients (11%) were transplanted. One patient was switched to a left ventricular assist device and was then successfully transplanted. Twenty-one patients (55%) survived to hospital discharge. Conclusions. The Mobile Cardiac Assist unit allowed emergency implantation of ECMO support in remote institutions without any logistic or technical problems. (Ann Thorac Surg 2010;90: ) 2010 by The Society of Thoracic Surgeons Accepted for publication June 16, Presented at the Poster Session of the Forty-sixth Annual Meeting of The Society of Thoracic Surgeons, Fort Lauderdale, FL, Jan 25 27, Address correspondence to Dr Gariboldi, Service de Chirurgie Cardiaque, Hôpital de la Timone Adultes, 264, rue St Pierre, Marseille, 13005, France; vlad.gariboldi@ap-hm.fr. Extracorporeal membrane oxygenation (ECMO) is an effective technique to provide emergency mechanical pulmonary and circulatory assistance in patients with cardiogenic shock refractory to conventional critical care therapies, and hypoxic-hypercapnic respiratory failure resistant to advanced ventilation strategies. Extracorporeal membrane oxygenation has been successfully used as a bridge to myocardial recovery, heart transplantation, or implantation of left or biventricular assist devices in patients with overt cardiac failure of various etiologies (acute myocardial infarction, end-stage dilated cardiomyopathy, viral or toxic myocarditis, complication of cardiac surgery, cardiac arrest). As a result of progress in device technology, the extended use of this technique, and early identification of factors associated with better patient outcome, ECMO is now widely used in cardiac surgery institutions for such indications [1 5]. People with severe cardiogenic or pulmonary compromise are highly catecholamine dependent and mechanically ventilated and are usually unsuitable for transportation; therefore they are unable to benefit from high-tech medicine available only in specialized centers. For this reason, the Adult Cardiac Surgery Department of the Public University Hospital, Marseille, developed a Remote Cardiac Assist Unit in 2006, allowing our team to move to these institutions with the device and all the material necessary for the insertion of cardiac assistance, to implant the device with the patient in situ and transporting the patient back to our intensive care unit (ICU) for follow-up when hemodynamically stabilized, because larger institutions have greater expertise in the field of cardiac assist devices and transplantation. This study was undertaken to evaluate the feasibility of this procedure and to report the preliminary results of our experience. Patients and Methods This retrospective study reviewed all patients treated with emergency ECMO for cardiac arrest or cardiocirculatory shock resistant to conventional critical care treatment (systolic blood pressure 80 mm Hg, use of two or more inotropic agents, use of intraaortic balloon pump with signs of inadequate perfusion), or for hypoxichypercapnic respiratory failure resistant to advanced 2010 by The Society of Thoracic Surgeons /$36.00 Published by Elsevier Inc doi: /j.athoracsur

2 Ann Thorac Surg GARIBOLDI ET AL 2010;90: MOBILE ECMO UNIT ventilation strategies. The Ethics Committee of Timone Hospital approved the study protocol and a waiver of the requirement for written informed consent was obtained ECMO Circuit and Placement The extracorporeal system consists of a closed polyvinyl chloride circuit (Medtronic, Minneapolis, MN), a diffusion membrane oxygenator (Quadrox-D Bioline Coating, Jostra-Maquet, Orléans, France), a centrifugal pump (Bio-Medicus, Medtronic), and percutaneous 17 to 25 Fr venous and 17 to 19 Fr arterial femoral cannulae (Bio- Medicus Carmeda, Medtronic). The complete circuit, cannulae, and oxygenator were treated with heparin and Carmeda bioactive surface components (Carmeda AB, Upplands Vaesby, Sweden). An oxygen-air blender (Sechrist Industries, Anaheim, CA) was used to ventilate the membrane oxygenator. After injection of heparin (0.5 mg/kg), all cannulae were inserted through the percutaneous route according to the Seldinger technique to avoid bleeding during transport. An additional 5 to 7 Fr cannula was surgically inserted into the superficial femoral artery to prevent lower limb ischemia. In cases of isolated pulmonary failure (acute respiratory distress syndrome) without cardiac failure, the cannulae were inserted in both femoral veins to avoid arterial complications; one in the right atrium (outflow) and one in the inferior vena cava (inflow). These procedures were performed under general or local anesthesia, in the operating room if possible, but sometimes in the ICU when the patient was hemodynamically unstable or undergoing cardiac resuscitation. ADULT CARDIAC Inclusion and Exclusion Criteria All patients treated with emergency ECMO outside our institution, between March 2006 and June 2008, and subsequently transported back to our ICU by the mobile unit when stabilized were included. During this period, no patient implanted by our team was left in a remote institution. Exclusion criteria for transfer were the following: mean arterial pressure less than 50 mm Hg and cardiac index less than 2L min 1 m 2 despite high dose inotropic support, with refractory acidosis (base excess 8 meq/l), or severe hypoxemia (arterial difference in partial pressure of oxygen 50 mm Hg) despite optimal mechanical ventilation settings. A brief and quick evaluation was performed during cardiopulmonary resuscitation to preclude ECMO contraindications including previous irreversible brain damage, unobserved cardiac arrest, aortic dissection, age greater than 60 years, terminal malignancy, and chronic hepatic or renal failure (which are obvious contraindications for heart transplantation). These contraindications were the same as those used for patients inside our institution. Logistics Our mobile team is comprised of one cardiac surgeon, one anesthesiologist, and one perfusionist on call. All the material for implantation is ready 24 hours 7 days a week. When ECMO implantation is required outside our institution, road (ambulance) or air (helicopter EC 145, Eurocopter, Marignane France) transport is used to get to the patient as quickly as possible and to return the patient to our ICU. Results Characteristics of the Study Population From March 2006 to June 2008, 38 patients (23 men and 15 women) with a median age of years (range, 14 to 60 years) required placement of ECMO at the referring hospital and were then transported to Timone University Hospital. Interhospital transfer was accomplished by air in 11 cases and by ground ambulance in 27. The maximal time limit between the phone call and implantation was 90 minutes. Thirty-two patients had combined cardiopulmonary failure and were supported with a venoarterial bypass and six had isolated pulmonary failure and underwent placement of a venovenous bypass. For the patients with cardiocirculatory shock, mean left ventricular ejection fraction was 0.19 (0.10 to 0.25). Patients characteristics just before the implantation are summarized in Table 1. For all the patients implanted during resuscitation (n 6), cardiac arrest occurred intrahospital. In eight cases of the 32 patients with cardiac failure, a local physician had already inserted an intraaortic balloon pump. This was surgically removed during ECMO implantation in all cases. Percutaneous cannulation was performed uneventfully in all cases and no complications were observed. There were no logistic, technical, or device-related complications during ECMO implantation or patient transfers. During the period of the study we flew out twice and did not return with the patient nor implant the ECMO because the patients were already dead when we arrived. They were on resuscitation when we had the call and decided to mobilize the team because of the young age of these patients (24 and 36 years old). Table 1. Patients Characteristics Just Before ECMO Implantation (n 38) Characteristics Value Male (n) 23 Age (years SD) Weight (kg SD) Transfer distance (km), mean (range) 68 (1 230) Cardiac arrest (n) 6 Intraaortic balloon pump (n) 8 Brain natriuretic peptide (pg/ml SD) Blood lactate (mmol/l SD) Bilirubin ( mol/l SD) Prothrombin activity (% SD) Creatinine ( mol/l SD) Dobutamine ( g/kg/min SD) Epinephrine ( g/kg/min SD) Norepinephrine ( g/kg/min SD) ECMO extracorporeal membrane oxygenation.

3 1550 GARIBOLDI ET AL Ann Thorac Surg MOBILE ECMO UNIT 2010;90: Postoperative Course The postoperative course of the patients is summarized in Table 2. The ECMO system could be removed after a mean support time of 9.4 days (range, 2 hours to 33 days). The successful weaning rate was 50% (19 of 38). Three patients underwent heart transplantation, and one patient (3%) was switched to a left ventricular assist device and was then successfully transplanted. The survival rate to discharge was 55% (21 of 38). Postoperative Hospital Complications The postoperative complications experienced by the patients are shown in Table 3. Only two patients did not suffer any complication. Comment Table 3. Complications Observed in Patients Undergoing Extracorporeal Life Support (n 38) Complication Survivors (n 21) Nonsurvivors (n 17) p Value Acute renal failure, n (%) 9 (42.8) 14 (82.4) 0.08 Acute liver failure, n (%) 9 (42.8) 16 (94.1) Multiple organ failure, 4 (19) 14 (82.4) n (%) Sepsis, n (%) 12 (57.1) 8 (47.1) 0.38 Hemolysis, n (%) 3 (14.3) 3 (18) 0.25 Lower limb ischemia, 2 (9.5) 2 (11.8) 0.71 n (%) - requiring amputation 0 (0) 1 (5.9) Neurologic deficit, n (%) 5 (23.8) 9 (52.9) Transient ( 24 hours) 4 (19) 4 (23.5) - Permanent ( 24 hours) 1 (4.8) 5 (29.4) Interest in cardiopulmonary bypass support for the initial stabilization and subsequent safe transport of critically ill patients by air or ground ambulance has recently reemerged with the commercialization of downsized ECMO systems. Previous mobile ECMO systems such as Bennett s mobile ECMO cart have been described in the literature [6]. This device had a weight of 69 kg and a minimum of six people was required to load and unload the patient and ECMO safely and smoothly. It was often not possible to accommodate the flight crew, ECMO specialists, and physicians in a single vehicle. Despite providing a centrifugal pump and a membrane oxygenator for initiation of percutaneous cardiopulmonary support, there was no way of transferring critically ill patients with cardiopulmonary bypass as one unit on a standard patient gurney [7]. Our mobile ECMO unit has a weight of 25 kg and allows safe interhospital transfer on a standard gurney with the patient and ECMO as one unit. New miniaturized life support systems for mobile percutaneous cardiopulmonary bypass have been commercialized and should be adopted by specialist teams to improve transport conditions and to reduce the risk of cannula dislodgment or kinking. When introducing a mobile ECMO service, a number of factors must be taken into account that are beyond the scope of a conventional emergency transport service. The concept of our mobile team on-call around the clock is relaying on a phone network between all the emergency departments, all the cardiology intensive care units, and all the general intensive care units of the Southern-East of France and our ICU. These include the number of senior personnel required, including a cardiac surgeon, anesthesiologist, and perfusionist, and the fact that ECMO retrievals are lengthy and generally exceed a standard shift or working day. In fact, our team is on a call 24/7, with all circuit and cannulae in a special bag, able to leave our institution in 20 minutes as soon as the indication is validated, by ambulance or helicopter, depending on the presence of a drop-zone in the target hospital. If there is no drop zone or if the weather is bad we prefer to use a ground ambulance to avoid excessive movement of the patient. Thus, the maximal time limit between the phone call and implantation was 90 minutes. When patients were under cardiac arrest and resuscitation, we did not mobilize the team if cardiac arrest occurred outside hospital, because of the impossibility to evaluate neurologic status. When cardiac arrest occurred intrahospital, these patients were intact before, and our policy is to give the patient a chance unless some clinical factors suggest major neurologic damage. Placing a patient on cardiopulmonary support implies knowledge of the benefits and the risks of the procedure. Intracardiac clot formation and arterial thromboembolism are the most serious complications of ECMO and Table 2. Diagnosis, Duration of Extracorporeal Life Support, and Postoperative Course (n 38) Diagnosis n (%) ECMO Duration (Days) Weaning (n) Heart Transplantation (n) Death (n) Myocarditis 10 (26.4) Medical overdose 6 (15.8) Myocardial infarction 7 (18.4) Postpartum 3 (7.9) Cardiomyopathy 4 (10.5) ARDS 6 (15.8) Other 2 (5.2) 25 2 ARDS acute respiratory distress syndrome; ECMO extracorporeal membrane oxygenation.

4 Ann Thorac Surg GARIBOLDI ET AL 2010;90: MOBILE ECMO UNIT may potentially limit its use [8, 9]. After a single injection of 0.5 mg/kg of heparin, no more anticoagulation was given during transport to avoid bleeding, and continuous heparinization was undertaken once the patient arrived in our ICU. Like Saito and colleagues [10], we believe that systemic heparinization is essential for ECMO support to avoid thromboembolic events, although it may increase the frequency of bleeding events. In our experience, continuous systemic heparinization was performed routinely with monitoring of the target activated clotting time (approximately 140 to 150 seconds) and no bleeding or thromboembolic events occurred. The rate of ischemic complications after arterial vessel access has been reported to range from 18% to 70% in patients treated with percutaneous cardiopulmonary support through the femoral vessel [11], and was related to severe atherosclerosis, microembolism, and vasoconstriction due to coexisting catecholamine therapy. Limb ischemia developed in four of our patients after placement of the arterial cannula. Limb ischemia can be reduced by the systematic use of an antegrade femoral reperfusion catheter. Other cannulation techniques, such as the use of a Dacron T-graft (DuPont, Wilmington, DE) [12, 13], can be utilized to prevent ischemia but these do not seem to be appropriate for remote patients because of the potential for bleeding during transport. In such remote patients we believe that intraaortic balloon counterpulsation must be removed during ECMO implantation, even if the combined use of an intraaortic balloon and ECMO has several benefits [14]. This will reduce congestion in the ambulance or helicopter and decrease the risk of thromboembolic events. Concerning anesthesia, we prefer to implant ECMO in intubated, paralyzed, and sedated patients, because it is more comfortable for the patient and easier for the surgeon, and makes mobilization of the patient during transfer safer by avoiding leg movement. In some particular patients with extreme low flow (especially cerebral low flow) the guide wires and cannulae are inserted under local anesthesia to avoid cardiac arrest during induction of anesthesia, and then the patient is intubated once ECMO is running with optimal flow (2 to 2.4 L/min/m 2 ), and mean arterial pressure is between 60 and 90 mm Hg before departure. Once cardiopulmonary bypass support has been successfully initiated, the two most potentially serious complications during transport are cardiopulmonary bypass system failure and disruption, and inadvertent decannulation [15, 16]. General anesthesia, careful attention, and proper training of the medical transfer team can help avoid theses potentially hazardous events. Of course the cost of such a unit must be considered: each round trip costs approximately 27,000 US dollars, not including the price of the pump which is approximately 135,000 US dollars. However, this should not be a major concern because of the young age of these patients and the possibility that they can be transplanted if no recovery is observed. Patients greater than 60 years of age are considered for implantation and transfer if there is a possibility that they could be weaned [17] or bridged to other long-term assist devices. Indeed, because of the shortage of heart donors in France, we refuse to bridge patients who are greater than 60 years old on our transplantation list. As with on-site implantations, fulminant myocarditis had the best outcome in this study (70% survival to hospital discharge) and remains a good indication for ECMO compared with other assist devices [2, 18, 19] and a good indication for the mobile ECMO unit irrespective of the patient s age. On the other hand, survival was low (14%) in patients with acute myocardial infarction because of their older age, more frequent cardiovascular risk factors, and the presence of diffuse atherosclerosis in this population. Furthermore, acute myocardial infarction provokes an inflammatory response that leads to multiple organ failure for itself despite good flow ensured by ECMO [20]. Thus, the value of ECMO implantation in this indication is questionable, especially regarding patient s age and other comorbidities. Finally, we do not consider differences between patients inside or outside our institution whatever the indication for implantation. In our experience, critically ill patients who would not otherwise be transportable can now be safely transported long distances on ECMO. If appropriate resources exist, this intervention should be offered to carefully selected patients. References Chen YS, Ko WJ, Yu HY, et al. Analysis of the outcome for patients experiencing myocardial infarction and cardiopulmonary resuscitation refractory to conventional therapies necessitating extracorporeal life support rescue. Crit Care Med 2006;34: Chen YS, Yu HY, Huang KM, et al. Experience and results of extracorporeal membrane oxygenation in treating fulminant myocarditis with shock: what mechanical support should be considered first? J Heart Lung transplant 2005;24: Baud FJ, Megarbane B, Deye N, Leprince P. Clinical review: aggressive management and extracorporeal support for drug-induced cardiotoxicity. Crit Care 2007;11: Chen YS, Chao A, Yu HY, et al. Analysis and results of prolonged resuscitation in cardiac arrest patients rescued by extracorporeal membrane oxygenation. J Am Coll Cardiol 2003;41: Sidebotham D, McGeorge A, McGuinness S, Edwards M, Willcox T, Beca J. Extracorporeal membrane oxygenation for treating severe cardiac and respiratory disease in adults: part 1-overview of extracorporeal membrane oxygenation. J Cardiothorac Vasc Anesth 2009;23: Bennett JB, Hill JG, Long WB 3rd, Bruhn PS, Haun MM, Parsons JA. Interhospital transport of the patient on extracorporeal cardiopulmonary support. Ann Thorac Surg 1994; 57: Lindén V, Palmér K, Reinhard J, et al. Inter-hospital transportation of patients with severe acute respiratory failure on extracorporeal membrane oxygenation-national and international experience. Intensive Care Med 2001;27: Magovern GJ Jr, Simpson KA. Extracorporeal membrane oxygenation for adult cardiac support: The Allegheny experience. Ann Thorac Surg 1999;68: Muehrcke DD, McCarthy PM, Stewart RW, et al. Extracorporeal membrane oxygenation for postcardiotomy cardiogenic shock. Ann Thorac Surg 1996;61: ADULT CARDIAC

5 1552 GARIBOLDI ET AL Ann Thorac Surg MOBILE ECMO UNIT 2010;90: Saito S, Nakatani T, Kobayashi J, et al. Is extracorporeal life support contraindicated in elderly patients? Ann Thorac Surg 2007;83: Werman HA, Falcone RA, Shaner S, et al. Helicopter transport of patients to tertiary care centers after cardiac arrest. Am J Emerg Med 1999;17: Luo XJ, Wang W, Hu SS, et al. Extracorporeal membrane oxygenation for treatment of cardiac failure in adult patients. Interact Cardiovasc Thorac Surg 2009;9: Smith C, Bellomo R, Raman JS, et al. An extracorporeal membrane oxygenation-based approach to cardiogenic shock in an older population. Ann Thorac Surg 2001;71: Phillips SJ, Zeff RH, Kongtahworn C, et al. Benefits of combined balloon pumping and percutaneous cardiopulmonary bypass. Ann Thorac Surg 1992;54: Foley DS, Pranikoff T, Younger JG, et al. A review of 100 patients transported on extracorporeal life support. ASAIO J 2002;48: Bergman KA, Geven WB, Molendijk A, et al. Referral and transportation for neonatal extracorporeal membrane oxygenation. Eur J Emerg Med 2002;9: McBride LR, Lowdermilk GA, Fiore AC, Moroney DA, Brannan JA, Swartz MT. Transfer of patients receiving advanced mechanical circulatory support. J Thorac Cardiovasc Surg 2000;119: Pages ON, Aubert S, Combes A, et al. Paracorporeal pulsatile biventricular assist device versus extracorporal membrane oxygenation-extracorporal life support in adult fulminant myocarditis. J Thorac Cardiovasc Surg 2009;137: Chen YS, Wang MJ, Chou NK, et al. Rescue for acute myocarditis with shock by extracorporeal membrane oxygenation. Ann Thorac Surg 1999;68: Frangogiannis NG, Smith CW, Entman ML. The inflammatory response in myocardial infarction. Cardiovasc Res 2002;53: INVITED COMMENTARY As extracorporeal membrane oxygenation (ECMO) technology becomes more readily available, expansion of its use has been implemented in the resuscitation of out-of-hospital patients with cardiac or pulmonary failure refractory to conventional medical therapy. However, constraints in assessment, urgency to decision making, practical issues with cannulation, and logistics of patient transport add layers of difficulties to the already clinically challenging situations. Gariboldi and colleagues [1] reviewed an experience of 38 consecutive patients with ECMO initiation before transfer to their institution; of these, 32 had cardiopulmonary failure and 6 had isolated pulmonary failure. A detailed description of the logistics and equipment needs was provided along with the results of their experience. After a mean support of 9.4 days, survival was 55% to the end points of recovery, transplantation, and bridge to left ventricular assist device to transplantation. This was a retrospective observational study of a single cohort of ECMO patients, and therefore, no comparisons were made with similar in-hospital patients treated with ECMO support or otherwise by conventional means. However, despite the intrinsic drawbacks due to the nature of the study, this article offers practical insights into the operation of a mobile ECMO unit. Because time was of the essence in the establishment of ECMO in the critically ill, the report describes a dedicated team consisting of a cardiac surgeon, anesthesiologist, and perfusionist, with coverage at all times. This ECMO team, together with ready-to-go equipment and transportation, achieved a call-to-implant time of 90 minutes. The authors also described a telecommunication network of emergency departments and intensive care units in the region. Indeed, advances in telecommunications and information technology in today s world greatly aid the operation of such a mobile unit, not only in the communications between personnel involved but also in preintervention assessment through the review of patient information, hospital notes, laboratory results, and imaging, resulting in a much more efficient deployment of mobile ECMO. Prolonged cardiopulmonary support with ECMO has been a well-established modality in the care of neonates and adults with cardiac or cardiopulmonary failure. Its benefits and utility in the care of primary respiratory failure has been controversial. The results of two randomized trials were published on the use of ECMO vs conventional mechanical ventilation for the care of acute respiratory failure patients. One involved the use of venoarterial [2] and the second trial involved venovenous ECMO [3]. In neither trial did ECMO confer a survival benefit over conventional mechanical support. Since these trials, the development of perfusion technologies and the publications of better-than-expected survival with the use of ECMO led researchers to establish the Conventional Versus ECMO for Severe Adult Respiratory Failure (CESAR) trial [4], a randomized clinical and economic trial that ultimately involved 180 patients and 70 medical centers throughout the United Kingdom. The outcome of this trial showed significantly improved survival when patients were transferred to a center with an ECMO management protocol. The CESAR trial has potentially significant implications for policy makers, health care planning, and for the management of patients with acute respiratory distress syndrome, as well as for centers capable of providing this technology on whom increased demand for support might be asked. Indeed, after early H1N1 virus outbreaks in North America in April 2009, the new influenza virus spread rapidly around the world. By the time the World Health Organization declared a pandemic in June 2009, 74 countries and territories had reported laboratory-confirmed infections. To date, most countries in the world have confirmed infections from the new virus [5]. The H1N1 outbreak has really heightened the awareness of ECMO. The Extracorporeal Life Support Organization (ELSO), which is affiliated with the University of Michigan in Ann Arbor, reported a 72% survival rate for H1N1 patients who were placed on ECMO within 6 days of intubation between April and October of Another observational study conducted in Australia and New Zealand on patients with 2009 influenza A (H1N1) associated respiratory failure, one-third of whom received ECMO, confirmed the new optimism provided by the CESAR trial. [6]. With the rapidly expanding technology in extracorporeal circulation, there is a certain amount of evolution in hardware, allowing for a more portable system with less associated 2010 by The Society of Thoracic Surgeons /$36.00 Published by Elsevier Inc doi: /j.athoracsur