ASAIO journal : a peer-reviewed journal of the American Society for Artificial Internal Organs
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Advances in mechanical circulatory support have been critical in bridging patients awaiting heart transplantation. In addition, improvement in device durability has enabled left ventricular assist device therapy to be applied as destination therapy in those not felt to be transplant candidate. Because of the increasing complexity of patients, there continues to be a need for alternative strategies for device implantation to bridge high-risk patients awaiting heart transplantation, wherein the risks of numerous previous sternotomies may be prohibitive. We present a unique technique for placement of the HeartWare ventricular assist device via left anterior thoracotomy to the descending aorta in a patient awaiting heart transplantation with a history of multiple previous sternotomies.
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This study evaluated the effectiveness of an atrial septal defect (ASD) with venovenous extracorporeal membrane oxygenation (vv-ECMO) as a bridge to transplantation. Sheep (56 ± 3 kg; n = 7) underwent a right-sided thoracotomy to create the ASD (diameter = 1 cm) and place instrumentation and a pulmonary artery (PA) occluder. After recovery, animals were placed on ECMO, and the PA was constricted to generate a twofold rise in right ventricular (RV) systolic pressure. ⋯ Cardiac output was 6.8 ± 1.2 L/min at baseline, averaged 6.0 ± 1.0 L/min during the experiment, and was statistically unchanged (p = 0.34). Average arterial oxygen saturation and PCO2 over the experiment were 96.8 ± 1.4% and 31.8 ± 3.4 mm Hg, respectively. In conclusion, an ASD combined with vv-ECMO maintains normal systemic hemodynamics and arterial blood gases during a long-term increase in RV afterload.
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A mock circulatory system (MCS) has been proven a useful tool in the development of a ventricular assist device. Nowadays a MCS aimed at the evaluation of pediatric blood pumps, which require many different considerations compared with that of adults, has become an urgent need. This article presents the details on how the dynamic process of the left ventricle, which is described in terms of the pressure-volume loop (P-V loop), and the properties of the circulation such as compliance and resistance are simulated by hydraulic elements. ⋯ At last a pediatric left ventricular assist device (LVAD) prototype is introduced for testing to further verify the effectiveness of the MCS. The experimental results indicate that this pediatric MCS is capable of reproducing basic hemodynamic characteristics of a child in both normal and pathological conditions and it is sufficient for testing a pediatric LVAD. Besides, most components constituting the main hydraulic part of this MCS are inexpensive off-the-shelf products, making the MCS easy and fast to build.
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Noninvasive ventilatory support has become the standard of care for patients with chronic obstructive pulmonary disease (COPD) experiencing exacerbations leading to acute hypercapnic respiratory failure. Despite advances in the use of noninvasive ventilation and the associated improvement in survival, as many as 26% of these patients fail noninvasive support and have a higher subsequent risk of mortality than patients treated initially with invasive mechanical ventilation. We report the use of a novel device to avoid invasive mechanical ventilation in two patients who were experiencing acute hypercapnic respiratory failure because of an exacerbation of COPD and were deteriorating, despite support with noninvasive ventilation. ⋯ Neither patient required intubation, despite imminent failure of noninvasive ventilation before initiation of extracorporeal support. Both patients were weaned from noninvasive and extracorporeal support within 3 days. We concluded that low-flow extracorporeal carbon dioxide removal, or respiratory dialysis, is a viable option for avoiding intubation and invasive mechanical ventilation in patients with COPD experiencing an exacerbation who are failing noninvasive ventilatory support.
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Extracorporeal membrane oxygenation (ECMO) is recommended as a treatment modality for severe acute respiratory distress syndrome (PaO2/FiO2 ≤ 100 mm Hg with positive end-expiratory pressure ≥ 5 cm H2O) as defined by the Berlin definition. The reported usual duration of ECMO in these patients is 7-10 days. However, increasing reports of prolonged duration ECMO (>14 days) for respiratory failure document survival rates of 50-70% with native lung recovery, and ECMO bridge to lung transplantation has been performed at many centers. ⋯ We report a case of prolonged duration venovenous-ECMO (1,347 hours, 56.13 days), with native lung recovery and discuss treatment strategies to optimize native lung recovery in ECMO patients. The lung may have unexpected regenerative capacity with native lung recovery after prolonged mechanical support, similar to acute kidney injury and native renal recovery. We recommend redefining irreversible lung injury and futility in ECMO.