Extracorporeal membrane oxygenation in nonintubated patients as bridge to lung transplantation

Mechanical ventilation during extracorporeal membrane oxygenation support - New trends and continuing challenges

BACKGROUND

The impact of mechanical ventilation on the survival of patients supported with veno-venous extracorporeal membrane oxygenation (V-V ECMO) due to severe acute respiratory distress syndrome (ARDS) remains still a focus of research.

METHODS

Recent guidelines, randomized trials, and registry data underscore the importance of lung-protective ventilation during respiratory and cardiac support on ECMO.

RESULTS

This approach includes decreasing mechanical power delivery by reducing tidal volume and driving pressure as much as possible, using low or very low respiratory rate, and a personalized approach to positive-end expiratory pressure (PEEP) setting. Notably, the use of ECMO in awake and spontaneously breathing patients is increasing, especially as a bridging strategy to lung transplantation. During respiratory support in V-V ECMO, native lung function is of highest importance and adjustments of blood flow on ECMO, or ventilator settings significantly impact the gas exchange. These interactions are more complex in veno-arterial (V-A) ECMO configuration and cardiac support. The fraction on delivered oxygen in the sweep gas and sweep gas flow rate, blood flow per minute, and oxygenator efficiency have an impact on gas exchange on device side. On the patient side, native cardiac output, native lung function, carbon dioxide production (VCO2), and oxygen consumption (VO2) play a role. Avoiding pulmonary oedema includes left ventricle (LV) distension monitoring and prevention, pulse pressure >10 mm Hg and aortic valve opening assessment, higher PEEP adjustment, use of vasodilators, ECMO flow adjustment according to the ejection fraction, moderate use of inotropes, diuretics, or venting strategies as indicated and according to local expertise and resources.

CONCLUSION

Understanding the physiological principles of gas exchange during cardiac support on femoro-femoral V-A ECMO configuration and the interactions with native gas exchange and haemodynamics are essential for the safe applications of these techniques in clinical practice. Proning during ECMO remains to be discussed until further data is available from prospective, randomized trials implementing individualized PEEP titration during proning.

Extracorporeal Life Support in Pulmonary Hypertension: Practical Aspects

Extracorporeal life support (ECLS), in particular veno-arterial extracorporeal membrane oxygenation, has emerged as a potentially life-saving treatment modality in patients presenting with pulmonary hypertension and right heart failure refractory to conventional treatment. Used mainly as a bridge to lung transplantation, ECLS is also being used occasionally as a bridge to recovery in patients with treatable causes of right heart failure. This review article describes indications, contraindications, techniques, and outcomes of the use of ECLS in patients with PH, focusing on practical aspects in the management of such patients.

Extracorporeal Membrane Oxygenation Without Invasive Ventilation for Respiratory Failure in Adults: A Systematic Review

OBJECTIVES

Extracorporeal membrane oxygenation (ECMO) is an advanced treatment for acute severe respiratory failure. Patients on ECMO are frequently maintained sedated and immobilized until weaning from ECMO, first, and then from mechanical ventilation. Avoidance of sedation and invasive ventilation during ECMO may have potential advantages. We performed a systematic literature review to assess efficacy and safety of awake ECMO without invasive ventilation in patients with respiratory failure.

DATA SOURCES

PubMed, Web of Science, and Scopus were searched for studies reporting outcome of awake ECMO for adult patients with respiratory failure.

STUDY SELECTION

We included all studies reporting outcome of awake ECMO in patients with respiratory failure. Studies on ECMO for cardiovascular failure, cardiac arrest, or perioperative support and studies on pediatric patients were excluded. Two investigators independently screened and selected studies for inclusion.

DATA EXTRACTION

Two investigators abstracted data on study characteristics, rate of awake ECMO failure, and mortality. Primary outcome was rate of awake ECMO failure (need for intubation). Pooled estimates with corresponding 95% CIs were calculated. Subgroup analyses by setting were performed.

DATA SYNTHESIS

A total of 57 studies (28 case reports) included data from 467 awake ECMO patients. The subgroup of patients with acute respiratory distress syndrome showed a pooled estimate for awake ECMO failure of 39.3% (95% CI, 24.0-54.7%), while in patients bridged to lung transplantation, pooled estimate was 23.4% (95% CI, 13.3-33.5%). Longest follow-up mortality was 121 of 439 (pooled estimate, 28%; 95% CI, 22.3-33.6%). Mortality in patients who failed awake ECMO strategy was 43 of 74 (pooled estimate, 57.2%; 95% CI, 40.2-74.3%). Two cases of cannula self-removal were reported.

CONCLUSIONS

Awake ECMO is feasible in selected patients, although the effect on outcome remains to be demonstrated. Mortality is almost 60% in patients who failed awake ECMO strategy.

Lung Transplantation for Pulmonary Arterial Hypertension

TOPIC IMPORTANCE

Even though patients with pulmonary arterial hypertension have multiple therapeutic options, the disease can be refractory despite appropriate management. In patients with end-stage pulmonary arterial hypertension, lung transplantation has the potential both to extend survival and improve health-related quality of life. Pulmonary arterial hypertension is the only major diagnostic indication for transplantation that is not a parenchymal pulmonary process, and thus the care of these patients is unique.

REVIEW FINDINGS

This review focuses on the complexities of lung transplantation for patients with pulmonary arterial hypertension, presents the updated referral and listing criteria, and discusses the inequities in the organ allocation process that impact this disease group and the strategies to optimize outcomes for patients with pulmonary arterial hypertension who require lung transplantation.

SUMMARY

Lung transplantation is an effective and lifesaving therapy for patients with end-stage lung disease. Sadly, patients with pulmonary arterial hypertension face many challenges as it relates to transplantation including higher perioperative risks, inequities in the allocation system, and less favorable long-term outcomes. This review covers the complexities of transplantation in patients with pulmonary vascular disease.

Standardized approach for extubation during extracorporeal membrane oxygenation in severe acute respiratory distress syndrome: a prospective observational study

BACKGROUND

Extubation during extracorporeal oxygenation (ECMO) in severe acute respiratory distress syndrome (ARDS) has not been well studied. Despite the potential benefits of this strategy, weaning from ECMO before liberation from invasive mechanical ventilation remains the most frequent approach. Our aim was to evaluate the safety and feasibility of a standardized approach for extubation during ECMO in patients with severe ARDS.

RESULTS

We conducted a prospective observational study to assess the safety and feasibility of a standardized approach for extubation during ECMO in severe ARDS among 254 adult patients across 4 intensive care units (ICU) from 2 tertiary ECMO centers over 6 years. This consisted of a daily assessment of clinical and gas exchange criteria based on an Extracorporeal Life Support Organization guideline, with extubation during ECMO after validation by a dedicated intensive care medicine specialist. Fifty-four (21%) patients were extubated during ECMO, 167 (66%) did not reach the clinical criteria, and in 33 (13%) patients, gas exchange precluded extubation during ECMO. At ECMO initiation, there were fewer extrapulmonary organ dysfunctions (lower SOFA score [OR, 0.88; 95% CI, 0.79-0.98; P = .02] with similar PaO2/FiO2) when compared with patients not extubated during ECMO. Extubation during ECMO associated with shorter duration of invasive mechanical ventilation (7 (4-18) vs. 32 (18-54) days; P < .01) and of ECMO (12 (7-25) vs. 19 (10-41) days; P = .01). This was accompanied by a lower incidence of hemorrhagic shock (2 vs. 11%; P = .05), but more cannula-associated deep vein thrombosis (49 vs. 31%; P = .02) and failed extubation (20 vs. 6%; P < .01). There were no increased major adverse events. Extubation during ECMO is associated with a lower risk of all-cause death, independently of measured confounding (adjusted logistic regression OR 0.23; 95% confidence interval 0.08-0.69, P = .008).

CONCLUSIONS

A standardized approach was safe and feasible allowing extubation during ECMO in 21% of patients with severe ARDS, selecting patients who will have a shorter duration of invasive mechanical ventilation, ECMO course, and ICU stay, as well as fewer infectious complications, and high hospital survival.

Enhanced extracorporeal carbon dioxide removal by acidification and metabolic control

BACKGROUND

Extracorporeal carbon dioxide removal (ECCO2R) promotes protective ventilation in patients with acute respiratory failure, but devices with high CO2 extraction capacity are required for clinically relevant impact. This study evaluates three novel low-flow techniques based on dialysate acidification, also combined with renal replacement therapy, and metabolic control.

METHODS

Eight swine were connected to a low-flow (350 mL/min) extracorporeal circuit including a dialyzer with a closed-loop dialysate circuit, and two membrane lungs on blood (MLb) and dialysate (MLd), respectively. The following 2-hour steps were performed: 1) MLb-start (MLb ventilated); 2) MLbd-start (MLb and MLd ventilated); 3) HLac (lactic acid infusion before MLd); 4) HCl-NaLac (hydrochloric acid infusion before MLd combined with renal replacement therapy and reinfusion of sodium lactate); 5) HCl-βHB-NaLac (hydrochloric acid infusion before MLd combined with renal replacement therapy and reinfusion of sodium lactate and sodium 3-hydroxybutyrate). Caloric and fluid inputs, temperature, blood glucose and arterial carbon dioxide pressure were kept constant.

RESULTS

The total MLs CO2 removal in HLac (130±25 mL/min), HCl-NaLac (130±21 mL/min) and HCl-βHB-NaLac (124±18 mL/min) were higher compared with MLbd-start (81±15 mL/min, P<0.05) and MLb-start (55±7 mL/min, P<0.05). Minute ventilation in HLac (4.3±0.9 L/min), HCl-NaLac (3.6±0.8 L/min) and HCl-βHB-NaLac (3.6±0.8 L/min) were lower compared to MLb-start (6.2±1.1 L/min, P<0.05) and MLbd-start (5.8±2.1 L/min, P<0.05). Arterial pH was 7.40±0.03 at MLb-start and decreased only during HCl-βHB-NaLac (7.35±0.03, P<0.05). No relevant changes in electrolyte concentrations, hemodynamics and significant adverse events were detected.

CONCLUSIONS

The three techniques achieved a significant extracorporeal CO2 removal allowing a relevant reduction in minute ventilation with a sufficient safety profile.

Fundamentals of weaning veno-arterial and veno-venous extracorporeal membrane oxygenation

Recent advances in veno-arterial (VA) and veno-venous (VV) extracorporeal membrane oxygenation (ECMO) technology and management have enabled us to support patients with cardiac and/or pulmonary failure, who may have previously been considered untreatable. VA ECMO and VV ECMO are by definition transient therapies and serve as a bridge to recovery, bridge to decision, bridge to transplant, or bridge to no recovery. Weaning ECMO should be considered for all patients once native cardiac and pulmonary function show signs of recovery. Currently, there are no universally accepted protocols for weaning VA and VV ECMO, and consequently, each individual center follows their own weaning protocols. The aim of this review article is to describe different approaches to safely wean from VA and VV ECMO.

Mechanical circulatory support devices and treatment strategies for right heart failure

The importance of right heart failure (RHF) treatment is magnified over the years due to the increased risk of mortality. Additionally, the multifactorial origin and pathophysiological mechanisms of RHF render this clinical condition and the choices for appropriate therapeutic target strategies remain to be complex. The recent change in the United Network for Organ Sharing (UNOS) allocation criteria of heart transplant may have impacted for the number of left ventricular assist devices (LVADs), but LVADs still have been widely used to treat advanced heart failure, and 4.1 to 7.4% of LVAD patients require a right ventricular assist device (RVAD). In addition, patients admitted with primary left ventricular failure often need right ventricular support. Thus, there is unmet need for temporary or long-term support RVAD implantation exists. In RHF treatment with mechanical circulatory support (MCS) devices, the timing of the intervention and prediction of duration of the support play a major role in successful treatment and outcomes. In this review, we attempt to describe the prevalence and pathophysiological mechanisms of RHF origin, and provide an overview of existing treatment options, strategy and device choices for MCS treatment for RHF.

Managing pulmonary arterial hypertension: how to select and facilitate successful transplantation

PURPOSE OF REVIEW

Despite improvements in available medical therapies, pulmonary arterial hypertension (PAH) remains a progressive, ultimately fatal disorder. Lung transplantation is a viable treatment option for PAH patients with advanced disease.

RECENT FINDINGS

Recent guidelines from the International Society of Heart and Lung Transplantation (ISHLT) have updated recommendations regarding time of referral and listing for lung transplantation in PAH. The new guidelines emphasize earlier referral for transplant evaluation to ensure adequate time for proper evaluation and listing. They also incorporate objective risk stratification criteria to assist in decision-making regarding timing of referral and listing. With regards to the transplant procedure, bilateral lung transplantation has largely supplanted heart-lung transplantation as the procedure of choice for transplantation for advanced PAH. Exceptions to this include patients with PAH because of congenital heart disease and those with concurrent LV dysfunction. Use of mechanical support via venoarterial ECMO initiated before transplantation and continued into the early postoperative period is emerging as a standard of care and may help to reduce early posttransplant mortality in this population. There has been increased recognition of the importance of WHO Group 3 pulmonary hypertension. Many of the lessons learned from PAH may be applied when transplanting patients with severe WHO Group 3 pulmonary hypertension.

SUMMARY

Patients with PAH present unique challenges with regards to transplantation that require a therapeutic approach distinct from other lung disorders. Lung transplantations for PAH are high-risk endeavors best performed at centers with expertise in management of both PAH and extracorporeal support.

Extracorporeal Membrane Oxygenation in Congenital Heart Disease

Mechanical circulatory support (MCS) is a key therapy in the management of patients with severe cardiac disease or respiratory failure. There are two major forms of MCS commonly employed in the pediatric population—extracorporeal membrane oxygenation (ECMO) and ventricular assist device (VAD). These modalities have overlapping but distinct roles in the management of pediatric patients with severe cardiopulmonary compromise. The use of ECMO to provide circulatory support arose from the development of the first membrane oxygenator by George Clowes in 1957, and subsequent incorporation into pediatric cardiopulmonary bypass (CPB) by Dorson and colleagues. The first successful application of ECMO in children with congenital heart disease undergoing cardiac surgery was reported by Baffes et al. in 1970. For the ensuing nearly two decades, ECMO was performed sparingly and only in specialized centers with varying degrees of success. The formation of the Extracorporeal Life Support Organization (ELSO) in 1989 allowed for the collation of ECMO-related data across multiple centers for the first time. This facilitated development of consensus guidelines for the use of ECMO in various populations. Coupled with improving ECMO technology, these advances resulted in significant improvements in ECMO utilization, morbidity, and mortality. This article will review the use of ECMO in children with congenital heart disease.

Awakening in extracorporeal membrane oxygenation as a bridge to lung transplantation

Although the rate of lung transplantation (LTx), the last treatment option for end-stage lung disease, is increasing, some patients waiting for LTx need a bridging strategy for LTx due to the limited number of available donor lungs. For a long time, mechanical ventilation has been employed as a bridge to LTx because the outcome of using extracorporeal membrane oxygenation (ECMO) as a bridging strategy has been poor. However, the outcome after mechanical ventilation as a bridge to LTx was poor compared with that in patients without bridges. With advances in technology and the accumulation of experience, the outcome of ECMO as a bridge to LTx has improved, and the rate of ECMO use as a bridging strategy has increased over time. However, whether the use of ECMO as a bridge to LTx can achieve survival rates similar to those of non-bridged LTx patients remains controversial. In 2010, one center introduced awake ECMO strategy for LTx bridging, and its use as a bridge to LTx has been showing favorable outcomes to date. Awake ECMO has several advantages, such as maintenance of physical activity, spontaneous breathing, avoidance of endotracheal intubation, and reduced use of sedatives and analgesics, but it may cause serious problems. Nonetheless, several studies have shown that awake ECMO performed by a multidisciplinary team is safe. In cases where ECMO or mechanical ventilation is required due to unavoidable exacerbation in patients awaiting LTx, the application of awake ECMO performed by an appropriately trained ECMO multi-disciplinary team can be useful.

Intraoperative support during lung transplantation

The role of intraoperative mechanical support during lung transplantation (LTx) is essential to provide a safe hemodynamic and ventilatory status during critical intraoperative events. This hemodynamic and ventilatory stability is vital to minimize the odds of suboptimal outcomes, especially considering that, due to the scarcity of donors and the fact that more and more patients with significant comorbidities are being considered for this therapy, a more aggressive approach is often needed by the transplant centers. Hence, the attenuation of any potential injury that can happen during this complex event is paramount. While a thorough assessment of the donor and optimization of postoperative care is pursued, certainly protective intraoperative management would also contribute to better outcomes. Understanding each patient’s underlying anatomy and cardiopulmonary physiology, associated with awareness of critical events during a complicated procedure like LTx, is essential for a precise indication and safe use of support. Cardiopulmonary bypass (CPB) and veno-arterial extracorporeal membrane oxygenation (VA ECMO) have been the most common approaches used, with the latter gaining popularity more recently and we have used VA ECMO exclusively for the last decade. New technologies certainly contributed to more liberal use of VA ECMO intraoperatively, enabling a protecting and physiologic environment for the newly implanted grafts. In this setting, potential prophylactic use for lung protection during a critical period is also considered.

Lung transplantation for pediatric pulmonary arterial hypertension-quo vadis?

In children with pulmonary arterial hypertension, lung transplantation illustrates a feasible treatment option once pharmacological therapy is exhausted. Timing of listing for lung transplantation in children remains difficult since hemodynamic deterioration often occurs abruptly and the time on the waiting list is usually hard to predict. Clear contraindications for lung transplantation are recent history of malignancies as well as irreversible end-organ failure. Generally, patients with pulmonary arterial hypertension in the absence of structural cardiac defects can safely undergo bilateral lung transplantation, combined heart-lung transplantation remains a procedure with a higher perioperative risk and should only be performed in selected cases with irreversible structural defects. Donor selection in recent years shows donors with extended criteria as well as lobar transplantation with good outcome, having the positive effect of broadening of the donor pool. Bridging to lung transplantation with veno-arterial ECMO treatment is feasible and has a good outcome in experienced transplant centers. Surgical considerations should include the risk of hemodynamic decompensation upon anesthesia induction and the need for extracorporeal support pre-, intra- and postoperative. Lung transplantation should be performed on veno-arterial ECMO support with either peripheral (>20 kg) or central cannulation (<20 kg). The surgical transplantation procedure includes the bronchial anastomosis as well as anastomoses of the pulmonary artery and the left atrium. Postoperative prolonged veno-arterial ECMO treatment for the immediate postoperative period allows for left ventricular remodeling given the new hemodynamic circumstances with lower pulmonary vascular resistance. Standard triple immunosuppression in most lung transplant programs currently includes steroids, mycophenolate mofetil and tacrolimus. Survival after pediatric lung transplantation for IPAH is comparable to pediatric lung transplants for other underlying diseases with a 1-year survival of approx. 80% and a 5-year survival of 64-65%. Therefore, evolving techniques in the field of lung transplantation led to overall improved survival prospects in children with end-stage pulmonary vascular disease.

Extracorporeal membrane oxygenation (ECMO): Radiographic appearances, complications and imaging artefacts for radiologists

Extracorporeal membrane oxygenation (ECMO) is a form of cardiopulmonary support primarily used in cardiothoracic and intensive care unit (ICU) settings. The purpose of this review is to familiarise radiologists with the imaging features of ECMO devices, their associated complications and appropriate imaging protocols for contrast-enhanced CT imaging of ECMO patients. This paper will provide a brief introduction to ECMO and the imaging modalities utilised in ECMO patients, followed by a description of the types of ECMO available and cannula positioning. Indications and contraindications for ECMO will be outlined followed by a description of the complications associated with ECMO, which radiologists should recognise. Finally, the imaging protocol and interpretation of contrast-enhanced CT imaging in ECMO patients will be discussed. In the current clinical climate with millions of COVID-19 cases around the world and tens of thousands of critically ill patients, many requiring cardiopulmonary support in intensive care units, the use of ECMO in adults has increased, and thus so has the volume of imaging. Radiologists need to be familiar with the types of ECMO available, the correct positioning of the catheters depending on the type of ECMO being utilised, and the associated complications and imaging artefacts.

Awake Extracorporeal Membrane Oxygenation for Acute Respiratory Distress Syndrome: Which Clinical Issues Should Be Taken Into Consideration

With the goal of protecting injured lungs and extrapulmonary organs, venovenous extracorporeal membrane oxygenation (VV-ECMO) has been increasingly adopted as a rescue therapy for patients with severe acute respiratory distress syndrome (ARDS) when conventional mechanical ventilation failed to provide effective oxygenation and decarbonation. In recent years, it has become a promising approach to respiratory support for awake, non-intubated, spontaneously breathing patients with respiratory failure, referred to as awake ECMO, to avoid possible detrimental effects associated with intubation, mechanical ventilation, and the adjunctive therapies. However, several complex clinical issues should be taken into consideration when initiating and implementing awake ECMO, such as selecting potential patients who appeared to benefit most; techniques to facilitating cannulation and maintain stable ECMO blood flow; approaches to manage pain, agitation, and delirium; and approaches to monitor and modulate respiratory drive. It is worth mentioning that there had also been some inherent disadvantages and limitations of awake ECMO compared to the conventional combination of ECMO and invasive mechanical ventilation. Here, we review the use of ECMO in awake, spontaneously breathing patients with severe ARDS, highlighting the issues involving bedside clinical practice, detailing some of the technical aspects, and summarizing the initial clinical experience gained over the past years.

Extracorporeal membrane oxygenation in critically ill neonatal and pediatric patients with acute respiratory failure: a guide for the clinician

Intro: Extracorporeal membrane oxygenation for neonatal and pediatric respiratory failure continues to demonstrate improving outcomes, largely due to advances in technology along with refined management strategies despite mounting patient acuity and complexity. Successful use of ECMO requires thoughtful initiation and candidacy strategies, along with reducing the risk of ventilator induced lung injury and the progression to multiorgan failure.Areas Covered: This review describes current ECMO management strategies for neonatal and pediatric patients with acute refractory respiratory failure and summarizes relevant published literature. ECMO initiation and candidacy, along with ventilator and sedation management, are highlighted. Additionally, rapidly expanding areas of interest such as anticoagulation strategies, transfusion thresholds, rehabilitation on ECMO, and drug pharmacokinetics are described.Expert Opinion: Over the last few decades, published studies supporting ECMO use for acute refractory respiratory failure, along with institutional experience, have resulted in increased utilization although more randomized-controlled trials are needed. Future research should focus on filling the knowledge gaps that remain regarding anticoagulation, transfusion thresholds, ventilator strategies, sedation, and approaches to rehabilitation to subsequently implement into clinical practice. Additionally, efforts should focus on well-designed trials, including population pharmacokinetic studies, to develop dosing recommendations.

Extracorporeal Membrane Oxygenation as a Bridge to Lung Transplant

Extracorporeal membrane oxygenation (ECMO) is a cardiopulmonary technology capable of supporting cardiac and respiratory function in the presence of end-stage lung disease. Initial experiences using ECMO as a bridge to lung transplant (ECMO-BTLT) were characterized by high rates of ECMO-associated complications and poor posttransplant outcomes. More recently, ECMO-BTLT has garnered success in preserving patients' physiologic condition and candidacy prior to lung transplant due to technological advances and improved management. Despite recent growth, clinical practice surrounding use of ECMO-BTLT remains variable, with little data to inform optimal patient selection and management. Although many questions remain, the use of ECMO-BTLT has shown promising outcomes suggesting that ECMO-BTLT can be an effective strategy to ensure that complex and rapidly decompensating patients with end-stage lung disease can be safely transplanted with good outcomes. Further studies are needed to refine and inform practice patterns, management, and lung allocation in this high-risk and fragile patient population.

Periprocedural safety and outcome after pump implantation for intravenous treprostinil administration in patients with pulmonary arterial hypertension

Methods

In this retrospective observational study, we analyzed all patients with pulmonary arterial hypertension undergoing LenusPro® pump implantation between November 2013 and October 2019 at our center. Periprocedural safety was assessed by describing all complications that occurred within 28 days after surgery; complications that occurred later were described to assess long-term safety. Clinical outcomes were measured by comparison of clinical parameters and echocardiographic measurements of right ventricular function from baseline to 6-months-follow-up.

Results

Fifty-four patients underwent LenusPro® pump implantation for intravenous treprostinil treatment during the investigation period. Periprocedural complications occurred in 5 patients; the only anesthesia-related complication (right heart failure with recovery after prolonged intensive care and death in the further course) occurred in the only patient who underwent general anesthesia. All other patients underwent local anesthesia with or without short-acting (analgo-) sedation. Eighteen long-term complications occurred in 15 patients, most notably pump pocket or catheter related problems. Transplant-free survival rates at 1, 2, and 3 years were 77 %, 56 %, and 48 %, respectively.

Conclusions

Subcutaneous pump implantation under local anesthesia and conscious analgosedation while avoiding intubation and mechanical ventilation is feasible in patients with advanced PAH. Controlled studies are needed to determine the safest anesthetic approach for this procedure.

Background/Objectives

Intravenous treprostinil treatment via a fully implantable pump is a treatment option for patients with advanced pulmonary arterial hypertension. However, there is no consensus on the preferred anesthetic approach for the implantation procedure. Primary objective was to assess periprocedural safety with particular attention to feasibility of local anesthesia and conscious analgosedation instead of general anesthesia. Long-term safety and clinical outcomes were secondary endpoints.

Implementation of Venoarterial Extracorporeal Membrane Oxygenation in Nonintubated Patients

Background

Although extracorporeal membrane oxygenation (ECMO) is generally performed percutaneously, the technology is deployed under sedation and necessitates endotracheal intubation. However, in some patients, the use of venoarterial (VA) ECMO without intubation may be beneficial. Herein, we describe our experiences with VA ECMO performed without prior endotracheal intubation.

Methods

A total of 783 patients treated with VA ECMO at a single center between January 2013 and July 2018 were reviewed retrospectively. We included patients who underwent successful VA ECMO implementation without prior endotracheal intubation, and excluded those who were younger than 18 years, had ongoing cardiopulmonary resuscitation status, and had poor quality of the vessels needed for percutaneous cannulation. The primary study outcome was in-hospital survival.

Results

In total, 50 patients were included in this study, 94% of whom showed cardiogenic shock. The mean age of the study participants was 56.3±14.5 years. The median VA ECMO support time was 7 days (range, 2–13 days). Twenty-one patients (42%) did not receive ventilator care during the VA ECMO support period, while 29 patients (58%) progressed to intubation after VA ECMO implementation. The rates of survival at discharge and weaning success were 82% (n=41) and 92% (n=46), respectively, and 80% (n=40) of patients presented good Glasgow–Pittsburgh Cerebral Performance Categories scores at discharge.

Conclusion

Even in patients with cardiogenic shock, percutaneous VA ECMO can be introduced safely without prior endotracheal intubation by an experienced care team. The application of nonintubated VA ECMO might be a feasible strategy in selected cases.

A case of broncho-cutaneous fistula secondary to tuberculosis successfully managed with awake veno-venous extracorporeal membrane oxygenation

A broncho-cutaneous fistula (BCF) is a communicating tract between the bronchus and the cutaneous surface of the thoracic wall and can be the primary presenting sign of several disease processes. It has been associated with positive pressure ventilation (PPV), post pneumonectomy, thoracostomy tubes, perforating chest trauma, neoplasia and chronic empyema. We report a case of a 45-year-old immunocompetent man presenting with severe hypercapnic respiratory failure secondary to a BCF as a result of tuberculosis (TB)-related empyema necessitans. Veno-venous extracorporeal membrane oxygenation (VV ECMO) was employed during spontaneous breathing to mitigate the risks of PPV, to facilitate diagnostics and enable targeted treatment. Awake VV ECMO is an effective supportive therapy for complex, destructive lung pathologies with a known reversible aetiology in which PPV would be potentially detrimental.

Veno-Venous Extracorporeal Lung Support as a Bridge to or Through Lung Volume Reduction Surgery in Patients with Severe Hypercapnia

Extracorporeal lung support (ECLS) represents an essential support tool especially for critically ill patients undergoing thoracic surgical procedures. Lung volume reduction surgery (LVRS) is an important treatment option for end-stage lung emphysema in carefully selected patients. Here, we report the efficacy of veno-venous ECLS (VV ECLS) as a bridge to or through LVRS in patients with end-stage lung emphysema and severe hypercapnia. Between January 2016 and May 2017, 125 patients with end-stage lung emphysema undergoing LVRS were prospectively enrolled into this study. Patients with severe hypercapnia caused by chronic respiratory failure were bridged to or through LVRS with low-flow VV ECLS (65 patients, group 1). Patients with preoperative normocapnia served as a control group (60 patients, group 2). In group 1, VV ECLS was implemented preoperatively in five patients and in 60 patients intraoperatively. Extracorporeal lung support was continued postoperatively in all 65 patients. Mean length of postoperative VV ECLS support was 3 ± 1 day. The 90 day mortality rate was 7.8% in group 1 compared with 5% in group 2 (p = 0.5). Postoperatively, a significant improvement was observed in quality of life, exercise capacity, and dyspnea symptoms in both groups. VV ECLS in patients with severe hypercapnia undergoing LVRS is an effective and well-tolerated treatment option. In particular, it increases the intraoperative safety, supports de-escalation of ventilatory strategies, and reduces the rate of postoperative complications in a cohort of patients considered "high risk" for LVRS in the current literature.

[Extracorporeal Lung Support in Thoracic Surgery: Basics and Pathophysiology]

Extracorporeal lung support (ECLS) is of increasing importance in general thoracic surgery. Different modes of ECLS may be applied in several situations throughout the perioperative phase and are adapted to the individual patient's needs and the planned surgical procedures. ECLS is not a static procedure and should be always evaluated according to the present condition of the patient. Therefore, it is essential to understand the pathophysiology of the disease and the different ECLS modes, as well as the different cannulation options, in order to be able to use the different escalation and de-escalation techniques in accordance with the clinical situation.

Low-Resistance, Concentric-Gated Pediatric Artificial Lung for End-Stage Lung Failure

Children with end-stage lung failure awaiting lung transplant would benefit from improvements in artificial lung technology allowing for wearable pulmonary support as a bridge-to-transplant therapy. In this work, we designed, fabricated, and tested the Pediatric MLung-a dual-inlet hollow fiber artificial lung based on concentric gating, which has a rated flow of 1 L/min, and a pressure drop of 25 mm Hg at rated flow. This device and future iterations of the current design are designed to relieve pulmonary arterial hypertension, provide pulmonary support, reduce ventilator-associated injury, and allow for more effective therapy of patients with end-stage lung disease, including bridge-to-transplant treatment.

Awake Neonatal Extracorporeal Membrane Oxygenation

Extracorporeal membrane oxygenation (ECMO) is used in patients with acute respiratory failure that is not responsive to conventional management. The practice of awake ECMO has become an area of interest but with limited data and experience. Most reported experience comes from adult and pediatric populations. Traditional management of these patients still includes mechanical ventilator support and often requires the use of sedatives for provision of safe care. We present a series of eight neonates who were electively extubated while on ECMO, with expanded discussion of two representative cases. We discuss the rationale for extubation and outcomes. The greatest benefit of this management was seen in patients with significant air leak, and in no reported case did we experience any adverse effects or complications as a direct result of extubation while on ECMO. In conclusion, in our experience, awake neonatal ECMO appears safe and effective and may offer significant advantages over traditional management in certain clinical scenarios. Prospective comparison trials are warranted to further investigate the clinical benefits and risks of awake neonatal ECMO.

Clinical Outcomes of Early Extubation Strategy in Patients Undergoing Extracorporeal Membrane Oxygenation as a Bridge to Heart Transplantation

BACKGROUND

Veno-arterial extracorporeal membrane oxygenation (VA-ECMO) might be considered a bridge therapy in patients who are expected to have short waiting times for heart transplantation. We investigated the clinical outcomes of patients who underwent VA-ECMO as a bridge to heart transplantation and whether the deployment of an early extubation ECMO strategy is beneficial.

METHODS

Between November 2006 and December 2018, we studied 102 patients who received VA-ECMO as a bridge to heart transplantation. We classified these patients into an early extubation ECMO group (n = 24) and a deferred extubation ECMO group (n = 78) based on the length of the intubated period on VA-ECMO (≤ 48 hours or > 48 hours). The primary outcome was in-hospital mortality.

RESULTS

The median duration of early extubation VA-ECMO was 10.0 (4.3-17.3) days. The most common cause for patients to be put on ECMO was dilated cardiomyopathy (65.7%) followed by ischemic cardiomyopathy (11.8%). In-hospital mortality rates for the deferred extubation and early extubation groups, respectively, were 24.4% and 8.3% (P = 0.147). During the study period, in the deferred extubation group, 60 (76.9%) underwent transplantation, while 22 (91.7%) underwent transplantation in the early extubation group. Delirium occurred in 83.3% and 33.3% of patients from the deferred extubation and early extubation groups (P < 0.001) and microbiologically confirmed infection was identified in 64.1% and 41.7% of patients from the two groups (P = 0.051), respectively.

CONCLUSION

VA-ECMO as a bridge therapy seems to be feasible for deployment in patients with a short waiting time for heart transplantation. Deployment of the early extubation ECMO strategy was associated with reductions in delirium and infection in this population.

Artificial lungs--Where are we going with the lung replacement therapy?

Lung transplantation may be a final destination therapy in lung failure, but limited donor organ availability creates a need for alternative management, including artificial lung technology. This invited review discusses ongoing developments and future research pathways for respiratory assist devices and tissue engineering to treat advanced and refractory lung disease. An overview is also given on the aftermath of the coronavirus disease 2019 pandemic and lessons learned as the world comes out of this situation. The first order of business in the future of lung support is solving the problems with existing mechanical devices. Interestingly, challenges identified during the early days of development persist today. These challenges include device-related infection, bleeding, thrombosis, cost, and patient quality of life. The main approaches of the future directions are to repair, restore, replace, or regenerate the lungs. Engineering improvements to hollow fiber membrane gas exchangers are enabling longer term wearable systems and can be used to bridge lung failure patients to transplantation. Progress in the development of microchannel-based devices has provided the concept of biomimetic devices that may even enable intracorporeal implantation. Tissue engineering and cell-based technologies have provided the concept of bioartificial lungs with properties similar to the native organ. Recent progress in artificial lung technologies includes continued advances in both engineering and biology. The final goal is to achieve a truly implantable and durable artificial lung that is applicable to destination therapy.

Extracorporeal membrane oxygenation as a bridge to lung transplantation in a Turkish lung transplantation program: our initial experience

Lung transplantation is a life-saving treatment for patients with end-stage lung disease. Although the number of lung transplants has increased over the years, the number of available donor lungs has not increased at the same rate, leading to the death of transplant candidates on waiting lists. In this paper, we presented our initial experience with the use of extracorporeal membrane oxygenation (ECMO) as a bridge to lung transplantation. Between December 2016 and August 2018, we retrospectively reviewed the use of ECMO as a bridge to lung transplantation. Thirteen patients underwent preparative ECMO for bridging to lung transplantation, and seven patients successfully underwent bridging to lung transplantation. The average age of the patients was 45.7 years (range, 19–62 years). The ECMO support period lasted 3–55 days (mean, 18.7 days; median, 13 days). In seven patients, bridging to lung transplantation was performed successfully. The mean age of patients was 49.8 years (range 42–62). Bridging time was 3–55 days (mean, 19 days; median, 13 days). Two patients died in the early postoperative period. Five patients survived until discharge from the hospital. One-year survival was achieved in four patients. ECMO can be used safely for a long time to meet the physiological needs of critically ill patients. The use of ECMO as a bridge to lung transplantation is an acceptable treatment option to reduce the number of deaths on the waiting list. Despite the successful results achieved, this approach still involves risks and complications.

Toward a Long-Term Artificial Lung

Only a very small portion of end-stage organ failures can be treated by transplantation because of the shortage of donor organs. Although artificial long-term organ support such as ventricular assist devices provide therapeutic options serving as a bridge-to-transplantation or destination therapy for end-stage heart failure, suitable long-term artificial lung systems are still at an early stage of development. Although a short-term use of an extracorporeal lung support is feasible today, the currently available technical solutions do not permit the long-term use of lung replacement systems in terms of an implantable artificial lung. This is currently limited by a variety of factors: biocompatibility problems lead to clot formation within the system, especially in areas with unphysiological flow conditions. In addition, proteins, cells, and fibrin are deposited on the membranes, decreasing gas exchange performance and thus, limiting long-term use. Coordinated basic and translational scientific research to solve these problems is therefore necessary to enable the long-term use and implantation of an artificial lung. Strategies for improving the biocompatibility of foreign surfaces, for new anticoagulation regimes, for optimization of gas and blood flow, and for miniaturization of these systems must be found. These strategies must be validated by in vitro and in vivo tests, which remain to be developed. In addition, the influence of long-term support on the pathophysiology must be considered. These challenges require well-connected interdisciplinary teams from the natural and material sciences, engineering, and medicine, which take the necessary steps toward the development of an artificial implantable lung.

Chronic Obstructive Pulmonary Disease and Lung Transplantation

Lung transplantation (LTx) has been a viable option for patients with end-stage chronic obstructive pulmonary disease (COPD), with more than 20,000 procedures performed worldwide. Survival after LTx lags behind most other forms of solid-organ transplantation, with median survival for COPD recipients being a sobering 6.0 years. Given the limited supply of suitable donor organs, not all patients with end-stage COPD are candidates for LTx. We discuss appropriate criteria for accepting patients for LTx, as well as contraindications and exclusionary criteria. In the first year post-LTx, infection and graft failure are the leading causes of death. Beyond this chronic graft rejection-currently referred to as chronic lung allograft dysfunction-represents the leading cause of death at all time points, with infection and over time malignancy also limiting survival. Referral of COPD patients to a lung transplant center should be considered in the presence of progressing disease despite maximal medical therapy. As a rule of thumb, a forced expiratory volume in 1 second < 25% predicted in the absence of exacerbation, hypoxia (PaO₂ < 60 mm Hg/8 kPa), and/or hypercapnia (PaCO₂ > 50 mm Hg/6.6 kPa) and satisfactory general clinical condition should be considered the basic prerequisites for timely referral. We also discuss salient issues post-LTx and factors that impact posttransplant survival and morbidity such as infections, malignancy, renal insufficiency, and complications associated with long-term immunosuppression.

Extubation and Noninvasive Ventilation of Patients Supported by Extracorporeal Life Support for Cardiogenic Shock: A Single-Center Retrospective Observational Cohort Study

Background:

Temporary extracorporeal life support (ECLS) by venoarterial extracorporeal membrane oxygenation is an emerging therapy for patients with severe, ongoing cardiogenic shock. After stabilization of the hemodynamic status and end-organ function, sedation weaning, extubation, and noninvasive ventilation (NIV) can be attempted. The goal of this study was to analyze the feasibility of extubation and NIV during versus after ECLS for cardiogenic shock.

Methods:

Single-center retrospective observational study of 132 patients undergoing ECLS due to severe cardiogenic shock between January 2015 and December 2016 at a tertiary care university hospital.

Results:

Patients received ECLS due to acute myocardial infarction (20.6%), ongoing cardiogenic shock (15.2%), postoperative low-cardiac-output syndrome (24.2%), and extracorporeal cardiopulmonary resuscitation (40.2%). Overall, intensive care unit survival was 44.7%. Sixty-nine (52.3%) patients could never be extubated. Forty-three (32.6%) were extubated while on ECLS support (group 1) and 20 (15.1%) were extubated after weaning from ECLS (group 2). Patients extubated during ECLS had a significantly shorter total time on ventilator (P = .003, mean difference: −284 hours [95% confidence limits: −83 to −484]) and more invasive ventilation free days (P = .0018; mean difference 8 days [95%CL: 2-14]). Mortality and NIV failure rates were similar between groups.

Conclusions:

Extubation and NIV are feasible in patients who stabilize during ECLS therapy. Further studies need to address whether extubation has the potential to improve patients outcome or if the feasibility to extubate is a surrogate for disease severeness.

[Management of right ventricular failure in pulmonary vascular diseases]

Right ventricular failure (RVF) is a common cause of admission to the intensive care unit and its presence is a major prognostic factor in acute pulmonary embolism (PE) and chronic pulmonary hypertension (PH). RVF results from an incapacity of the RV to adapt to an increase in afterload so it can become critical in acute PE and chronic PH. The presence of RVF in cases of acute PE with haemodynamic instability is an indication for thrombolytic therapy. RVF represents the most common cause of death in chronic PH. Factors triggering RV failure in PH, such as infection, PE, arrhythmias, or unplanned withdrawal of pulmonary arterial hypertension (PAH)-targeted therapy, have to be considered and treated if identified. However, RVF may also represent progression to end-stage disease. The management of RVF in patients with PH requires expertise and consists of optimization of fluid balance (with diuretics), cardiac output (with inotropic support such as dobutamine), perfusion pressure (with norepinephrine), and reduction of RV afterload with PAH-targeted therapies. Extracorporeal life support, lung transplantation or heart-lung transplantation should be considered in cases of refractory RVF in eligible patients.

Extracorporeal Membrane Oxygenation in the Perioperative Care of the Lung Transplant Patient

Lung transplantation (LT) is definitive therapy for end-stage lung disease. Donor allocation based on medical urgency has led to an increased trend in the transplantation of sicker and older patients. Mechanical ventilation (MV) formerly was the only method of bridging high-acuity patients to LT. When the physiological demands of ventilatory support exceeds the capability of MV, extracorporeal membrane oxygenation (ECMO) may become necessary. Recent improvements in ECMO technology and component design have led to a resurgence of interest in its use before, during, and after LT. Survival with ECMO as a bridge to LT has improved over time, now with many centers reporting little or no difference in outcomes, and some even reporting better outcomes, as compared with MV. Extracorporeal life support may also be used intraoperatively. In many studies to date, ECMO or cardiopulmonary bypass (CPB) has been reserved for patients who became hemodynamically unstable during the procedure or patients who could not tolerate single-lung ventilation. Both methods of support are fraught with potential complications. However, multiple studies comparing ECMO with CPB have shown that intraoperative use of ECMO resulted in improved outcomes and overall survival as well as lower rates of bleeding complications. In order to further reduce complications associated with ECMO, planned intraoperative ECMO use is occasionally reserved for high-risk patients who might otherwise require CPB. Future studies will need to improve patient selection to fully take advantage of the use of ECMO in LT while minimizing its costs.

Contemporary approaches in the use of extracorporeal membrane oxygenation to support patients waiting for lung transplantation

The introduction of the lung allocation score in 2005 prioritized patients with decreased transplant-free survival as the recipients of donor organs and effectively increased the number of critically-ill patients with end-stage lung disease waiting for transplantation. This change presented transplant programs with the challenge of how to both extend the lives of critically-ill, end-stage lung disease patients waiting for donor organs and maintain patient vitality to survival through the rigors of surgery and post-transplant recovery. Motivated by the dismal outcomes of patients maintained on mechanical ventilation pre-transplant, transplant centers increasingly deploy extracorporeal membrane oxygenation (ECMO) as a means of supporting patients with advanced disease as a bridge to successful lung transplantation. ECMO is an extracorporeal gas exchange device providing delivery of oxygen and removal of carbon dioxide from blood passed through the circuit. The specific cannulation strategy determines whether ECMO provides primarily respiratory or circulatory support. The cannulation approach is tailored to the specific physiological manifestations of the pre-lung transplant candidate's disease process. For patients with profound hypoxic respiratory failure, a cannulation strategy that captures a large fraction of the venous return is required to maintain adequate support whereas lower circuit flows are sufficient for patients with predominantly hypercapnic respiratory failure. Improving outcomes and increasing experience with ECMO is motivating transplant centers to initiate support before patients require mechanical ventilation. Awake cannulation is increasingly common and is used to avoid the complications associated with intubation in advanced lung failure. Determining criteria for initiation of support and identifying the optimal approach to support patients with right heart failure in need of circulatory support are avenues of active investigation. Use of ECMO and other forms of extracorporeal support are rapidly becoming a mainstay in the care of the pre-lung transplant patient with advanced disease.

The role of extracorporeal life support in the management with severe idiopathic pulmonary artery hypertension undergoing lung transplantation: are those patients referred too late?

Background

Idiopathic pulmonary artery hypertension (iPAH) is a relatively minor indication for lung transplantation (LTx) with comparatively poorer outcomes. Extracorporeal life support (ECLS) in various forms is increasingly being used in the management of this entity. However, the data and experience with this therapy remains limited. We evaluated the role of ECLS in the management of severe iPAH patients as a bridge to LTx as well as post LTx support.

Methods

A retrospective analysis of iPAH patients that received LTx between January 2007 and May 2014 was performed. Early- and mid-term outcomes were analyzed for this patient cohort. Also, early and mid-term outcomes after LTx were compared to the control group of patients with other diagnoses using unadjusted analysis and 1:3 propensity score matching.

Results

Of 321 LTx performed during the study period in our centre 15 patients had iPAH as a cause of end-stage lung disease. Four iPAH (27%) patients were bridged to LTx utilizing ECLS in the form of veno-arterial ECMO and extra-corporeal CO₂ removal device, whereas 9 patients (60%) required ECLS support for primary graft dysfunction (PGD) after surgery. Patients with iPAH required more frequently on-pump LTx, both pre and post LTx ECLS, and had significantly lower pO₂/FiO₂ ratio at 24, 48 and 72 hours after LTx. Also iPAH patients had significantly longer ICU and hospital stay. Whereas the incidence of postoperative bronchiolitis obliterans syndrome (BOS) and rejection was comparable to the control group, overall cumulative survival with up to 6 years follow-up was significantly poorer in the iPAH group. After propensity score matching, the results in terms of postoperative outcomes remained as in the unadjusted analysis.

Conclusions

ECLS is an essential tool in the armamentarium of any lung transplant program treating iPAH with a potential of bridge patients to transplantation and to overcome graft dysfunction after LTx. Despite utilization of ECLS in the management of iPAH, the outcomes in terms of primary graft failure and survival remain poor compared to patients with other diagnoses.

Extracorporeal membrane oxygenation as a bridge to lung transplantation may not impact overall mortality risk after transplantation: results from a 7-year single-centre experience

OBJECTIVES

Extracorporeal membrane oxygenation (ECMO) has an important role in bridging patients to lung transplantation. In this study, we present our experience with pretransplant ECMO during the last 7 years and investigate its impact on graft outcomes.

METHODS

Records of all lung-transplanted patients at our institution between January 2010 and April 2017 were retrospectively reviewed. Graft survival was compared between patients who required pretransplant ECMO (pre-Tx ECMO+) and patients who did not (pre-Tx ECMO-). Risk factors for in-hospital mortality and graft survival were identified using a binary logistic regression and the Cox regression analyses, respectively.

RESULTS

Among the 917 patients transplanted during the study period, 68 (7%) required ECMO as a bridge to transplantation [awake strategy, n = 57 (84%) patients]. Median bridging time was 9 days. Among pre-Tx ECMO+ patients, the need for haemodialysis at any point during bridging emerged as an independent risk factor for in-hospital mortality (odds ratio 7.79, 95% confidence interval 1.21-50.24; P = 0.031). Although in-hospital mortality was significantly higher in pre-Tx ECMO+ versus pre-Tx ECMO- patients (15% vs 5%, P = 0.003), overall graft survival did not differ between groups (79% vs 90% and 61% vs 68% at 1 and 5 years, respectively, P = 0.13). Pretransplant ECMO did not emerge as a risk factor for graft survival in the multivariable analysis.

CONCLUSIONS

If applied in selected patients in a high-volume centre, pretransplant ECMO as a bridge to transplantation results in impaired, but still high in-hospital, survival and does not impact graft survival.

Lung Transplantation as a Therapeutic Option in Acute Respiratory Distress Syndrome

BACKGROUND

Lung transplantation (LTPL) is considered as a salvage therapeutic option in patients with end-stage lung disease. However, there is a lack of sufficient data on the use of LTPL in patients with acute respiratory distress syndrome (ARDS). Although there are few case reports on lung transplant for ARDS, no case series exists up to date. The aim of this study was to evaluate the clinical outcomes of patients with ARDS in accordance with the LTPL status.

METHODS

Patients who had severe ARDS (PaO2/FiO2 ratio ≤ 100 mm Hg with positive end-expiratory pressure ≥ 5 cm H2O) and were listed for LTPL with no underlying end-stage lung disease were included in this single-center retrospective study. Demographic and clinical data of the patients were collected and analyzed.

RESULTS

Fourteen patients were listed for LTPL due to severe ARDS. All patients received mechanical ventilation, and 12 (86%) patients underwent extracorporeal membrane oxygenation. Of the 9 patients who underwent LTPL, 8 (89%) survived, whereas only 1 (20%) patient out of those who did not receive LTPL survived. The median survival time of the patients who underwent LTPL was 1996 days (interquartile range [IQR], 872-2239), compared with 49 days (IQR, 872-2239) in patients who did not undergo LTPL. The median survival time after LTPL was 64 months (IQR, 28-72). The 3-year survival rate of the recipients was 78%.

CONCLUSIONS

LTPL may be considered as a therapeutic option in a select group of patients with severe ARDS. However, the irreversibility of the patient's lung status should be considered.

Intensive care, right ventricular support and lung transplantation in patients with pulmonary hypertension

Intensive care of patients with pulmonary hypertension (PH) and right-sided heart failure includes treatment of factors causing or contributing to heart failure, careful fluid management, and strategies to reduce ventricular afterload and improve cardiac function. Extracorporeal membrane oxygenation (ECMO) should be considered in distinct situations, especially in candidates for lung transplantation (bridge to transplant) or, occasionally, in patients with a reversible cause of right-sided heart failure (bridge to recovery). ECMO should not be used in patients with end-stage disease without a realistic chance for recovery or for transplantation. For patients with refractory disease, lung transplantation remains an important treatment option. Patients should be referred to a transplant centre when they remain in an intermediate- or high-risk category despite receiving optimised pulmonary arterial hypertension therapy. Meticulous peri-operative management including the intra-operative and post-operative use of ECMO effectively prevents graft failure. In experienced centres, the 1-year survival rates after lung transplantation for PH now exceed 90%.

Awake and fully mobile patients on cardiac extracorporeal life support

Early mobilization of critically ill patients is increasingly being recognized as not only safe and feasible, but also as a potential means of optimizing outcomes in the intensive care unit (ICU). With the rapidly expanding use of extracorporeal life support (ECLS) for severe cardiopulmonary failure, there is a growing interest in the application of early mobilization to this patient population, which has been shown to be safe and feasible in select patient populations. However, some patients receiving ECLS support may benefit more than others. For instance, early mobilization may be particularly beneficial in patients awaiting heart or lung transplantation, as maintenance of physical conditioning may be an important component of a patient's transplant candidacy. The ability to engage critically ill patients in active physical therapy and early mobilization necessarily involves minimization of sedation and is often further facilitated by a strategy that favors endotracheal extubation. Whether an awake, extubated and mobile strategy can be applied in any given patient is often dictated by the severity of the underlying disease and the amount of extracorporeal support required. Additionally, whether this approach is superior to usual care, which patients might benefit or be harmed, and which patient characteristics are most likely to predict success of this strategy, are areas of ongoing investigation.

Early in vivo experience with the pediatric continuous-flow total artificial heart

BACKGROUND

Heart transplantation in infants and children is an accepted therapy for end-stage heart failure, but donor organ availability is low and always uncertain. Mechanical circulatory support is another standard option, but there is a lack of intracorporeal devices due to size and functional range. The purpose of this study was to evaluate the in vivo performance of our initial prototype of a pediatric continuous-flow total artificial heart (P-CFTAH), comprising a dual pump with one motor and one rotating assembly, supported by a hydrodynamic bearing.

METHODS

In acute studies, the P-CFTAH was implanted in 4 lambs (average weight: 28.7 ± 2.3 kg) via a median sternotomy under cardiopulmonary bypass. Pulmonary and systemic pump performance parameters were recorded.

RESULTS

The experiments showed good anatomical fit and easy implantation, with an average aortic cross-clamp time of 98 ± 18 minutes. Baseline hemodynamics were stable in all 4 animals (pump speed: 3.4 ± 0.2 krpm; pump flow: 2.1 ± 0.9 liters/min; power: 3.0 ± 0.8 W; arterial pressure: 68 ± 10 mm Hg; left and right atrial pressures: 6 ± 1 mm Hg, for both). Any differences between left and right atrial pressures were maintained within the intended limit of ±5 mm Hg over a wide range of ratios of systemic-to-pulmonary vascular resistance (0.7 to 12), with and without pump-speed modulation. Pump-speed modulation was successfully performed to create arterial pulsation.

CONCLUSION

This initial P-CFTAH prototype met the proposed requirements for self-regulation, performance, and pulse modulation.

Extubation of patients undergoing extracorporeal life support. A retrospective study

Introduction:

The use of extracorporeal life support (ECLS) is increasing worldwide, in particular for the management of refractory cardiac arrest, cardiogenic shock and post cardiopulmonary bypass ventricular failure. Extubation of patients under extracorporeal membrane oxygenation (ECMO) for respiratory failure is a growing practice for adult and pediatric patients, especially for lung transplantation candidates. Because of potential complications and, specifically, accidental arterial decannulation, extubation of patients under ECLS is not standard practice. Our goal was to evaluate the interest in patient extubation under ECLS.

Materials and methods:

We performed a monocentric, retrospective study of all ECLS cases between January 2014 and January 2016. We excluded patients who died within the first 48 hours of ECLS.

Results:

We analyzed 57 of the initial 109 patients included in the study. The initial SOFA score was higher in the non-extubated group under ECLS, without significant difference (8.6 ± 2.8 vs 7.2 ± 2.1, p=0.065). Patients who were not extubated had a higher rate of acquired ventilator pneumonia (61.9% vs 26.7%, p=0.03). Moreover, patients who were extubated under ECLS had better 30-day survival rates (73.3% vs 40.5%, p=0.04). In multivariate analyses, the independent factors associated with mortality were age, duration of ECLS and the lack of extubation under ECLS.

Conclusion:

Extubation of patients under ECLS is safe and feasible. Furthermore, in extubated patients, we observed fewer cases of ventilator-associated pneumonia and better 30-day survival rates.

Mid-term results of bilateral lung transplant with postoperatively extended intraoperative extracorporeal membrane oxygenation for severe pulmonary hypertension

OBJECTIVES

In severe pulmonary hypertension, diastolic dysfunction of the left ventricle causes significant morbidity and mortality after lung transplantation, which may be successfully reversed using a protocol based on perioperative veno-arterial extracorporeal membrane oxygenation (ECMO) and early extubation. Here, we present echocardiographic data and mid-term outcomes.

METHODS

The records of lung transplanted patients at our institution between May 2010 and January 2016 were retrospectively reviewed. Echocardiography data were collected preoperatively, at discharge, 3 and 12 months after transplantation.

RESULTS

During the study period, 717 patients underwent lung transplantation at our institution, 38 (5%) patients being transplanted for severe pulmonary hypertension. All patients underwent bilateral lung transplantation on veno-arterial ECMO cannulated in the groin, through a sternum sparing thoracotomy in 36 (95%) patients. Extubation was performed early, after a median of 2 days, and awake ECMO was extended for at least 5 days after transplantation. The survival at 3 months, 1 year and 5 years was not different in comparison to patients transplanted for other underlying diseases ( P  = 0.45). At 1 year, tricuspid valve regurgitation had disappeared in all patients. The median of the left ventricular end-diastolic dimension improved from 40 (32-44) mm preoperatively to 45 (44-47) mm at 12 months after lung transplantation ( P  < 0.05). The median of the proximal right ventricular outflow diameter decreased to 25 (23-27) mm after 12 months, compared to 48 (43-51) mm preoperatively ( P  < 0.05).

CONCLUSIONS

The routine application of a prophylactic postoperative veno-arterial ECMO protocol in patients with severe pulmonary hypertension undergoing lung transplantation decreases postoperative mortality and favours achievement of normal cardiac function after 1 year.

Idiopathic pulmonary fibrosis patient supported with extracorporeal membrane oxygenation for 403 days while waiting for a lung transplant: A case report

According to the Extracorporeal Life Support Organization, the average duration of veno-venous extracorporeal membrane oxygenation (V-V ECMO) in adults with acute respiratory failure is 10.5-13.5 days. Some patients on V-V ECMO may not recover in such a short period of time, and recently, there have been more reports of prolonged V-V ECMO. However, we do not know how long it is feasible to wait for native lung recovery or lung transplant (LTx) with the use of ECMO. We describe a patient with acute exacerbation of idiopathic pulmonary fibrosis supported by ECMO for 403 days while waiting for a LTx. In this case, we kept the patient awake, and he was communicating frequently with his family. We changed the membrane oxygenator 23 times and the cannula 10 times without complication. However, we terminated the treatment on day 403 of ECMO because there was no access site for cannula insertion due to blockage by a venous thrombotic occlusion, making it impossible to continue this bridge to lung transplantation. It has become possible to maintain patients on ECMO for extended periods of time, but it is difficult to manage ECMO for more than one year without the development of a more durable lung support system.

Tracheostomy as a bridge to spontaneous breathing and awake-ECMO in non-transplant surgical patients

AIMS

The tracheostomy is a frequently used procedure for the respiratory weaning of ventilated patients allows sedation free ECLS use in awake patient. The aim of this study is to assess the possibility and highlight the benefits of lowering the impact of sedation in surgical non-transplant patients on ECLS. The specific objective was to investigate the use of tracheostomy as a bridge to spontaneous breathing on ECLS.

METHODS AND RESULTS

Of the 95 patients, 65 patients received a tracheostomy, and 5 patients were admitted with a tracheostoma. One patient was cannulated without intubation, one is extubated during ECLS course after 48 hours. 4 patients were extubated after weaning and the removal of ECLS. 19 patients died before the indication to tracheostomy was given.

CONCLUSION

Tracheostomy can bridge to spontaneous breathing and awake-ECMO in non-transplant surgical patients. The "awake ECMO" strategy may avoid complications related to mechanical ventilation, sedation, and immobilization and provide comparable outcomes to other approaches for providing respiratory support.