Three Year Outcomes After Bridge to Transplantation ECMO - Pre- and Post- 2018 UNOS Revised Heart Allocation System.

BACKGROUND: Utilization of temporary mechanical circulatory support including veno-arterial extra-corporeal membrane oxygenation (VA-ECMO) as a bridge to heart transplantation (HT) has increased significantly under the revised United Network for Organ Sharing (UNOS) donor heart allocation system since October 2018. The revised heart allocation system aimed to lower waitlist times and mortality for the most critically ill patients requiring bi-ventricular, non-dischargeable, mechanical circulatory support. While previous reports have shown improved 1-year post-HT survival in the current Era, 3-year survival and factors associated with mortality among bridge to transplant (BTT) ECMO patients are not well described. METHODS: We queried the UNOS database for all adult (age ≥ 18 years) heart-only transplants performed between 2010 and 2019. Patients were stratified as either pre- (January 2010 to September 2018; Era 1) or post-allocation change (November 2018 to December 2019; Era 2) cohort based on their HT date. Baseline recipient characteristics and post-transplant outcomes were compared. A Cox regression analysis was performed to explore risk factors for 3-year mortality among BTT-ECMO patients in Era 2. For each Era, 3-year mortality was also compared between BTT ECMO patients and those transplanted without ECMO support. RESULTS: During the study period, 116 patients were BTT ECMO during Era 1 and 154 patients during Era 2. Baseline recipient characteristics were similar in both groups. Median age was 48 (36-58 IQR) years in Era 2 while it was 51 (27-58 IQR) years in Era 1. Majority of BTT-ECMO patients were males in both Era 2 and Era 1 (77.7% vs 71.5%, p = 0.28). Median ECMO run times while listed for HT were significantly shorter (4 days vs 7 days, p < 0.001) in Era 2. Waitlist mortality among BTT ECMO patients was also significantly lower in Era 2 (6.3% vs 19.3%, p < 0.001). Post-HT survival at 6 months (94.2% vs 75.9%, p < 0.001), 1 year (90.3% vs 74.2%, p < 0.001), and 3 years (87% vs 66.4%, p < 0.001) was significantly improved in Era 2 as compared to Era 1. Graft failure at 1 year (10.3% vs 25.8%, p = 0.0006) and 3 years (13.6% vs 33.6%, p=0.0001) was also significantly lower in Era 2 compared to Era 1. Three-year survival among BTT ECMO patients in Era 2 was similar to that of patients transplanted in Era 2 without ECMO support (87% vs 85.7%, p=0.75). In multi-variable analysis of BTT-ECMO patients in Era 2, every 1 kg/m2 increase in body mass index (BMI) was associated with higher mortality at 3 years (HR 1.09, 95% CI 1.02-1.15, p = 0.006). Similarly, both post-HT stroke (HR 5.58, 95% CI 2.57-12.14, p < 0.001) and post-HT renal failure requiring hemodialysis (HR 4.36, 95% CI 2.43-7.82, p < 0.001) were also associated with 3-year mortality. CONCLUSION: Three years post-HT survival in patients bridged with ECMO has significantly improved under the revised donor heart allocation system compared to prior system. BTT ECMO recipients under the revised system have significantly shorter ECMO waitlist run times, lower waitlist mortality and 3-year survival similar to those not bridged with ECMO. Overall, the revised allocation system has allowed more rapid transplantation of the sickest patients without a higher post-HT mortality.

Science of left ventricular unloading.

The concept of left ventricular unloading has its foundation in heart physiology. In fact, the left ventricular mechanics and energetics represent the cornerstone of this approach. The novel sophisticated therapies for acute heart failure, particularly mechanical circulatory supports, strongly impact on the mechanical functioning and energy consuption of the heart, ultimately affecting left ventricle loading. Notably, extracorporeal circulatory life support which is implemented for life-threatening conditions, may even overload the left heart, requiring additional unloading strategies. As a consequence, the understanding of ventricular overload, and the associated potential unloading strategies, founds its utility in several aspects of day-by-day clinical practice. Emerging clinical and pre-clinical research on left ventricular unloading and its benefits in heart failure and recovery has been conducted, providing meaningful insights for therapeutical interventions. Here, we review the current knowledge on left ventricular unloading, from physiology and molecular biology to its application in heart failure and recovery.

Femoro-axillary versus femoro-femoral veno-arterial extracorporeal membrane oxygenation for refractory cardiogenic shock: A monocentric retrospective study.

RATIONALE: For veno-arterial extracorporeal membrane oxygenation (ECMO), the femoral artery is the preferred cannulation site (femoro-femoral: Vf-Af). This results in retrograde aortic flow, which increases the left ventricular afterload and can lead to severe pulmonary edema and thrombosis of the cardiac chambers. Right axillary artery cannulation (femoral-axillary: Vf-Aa) provides partial anterograde aortic flow, which may prevent some complications. This study aimed to compare the 90-day mortality and complication rates between VF-AA and VF-AF. METHODS: Consecutive adult patients with cardiogenic shock who received peripheral VA-ECMO between 2013 and 2019 at our institution were retrospectively included. The exclusion criteria were refractory cardiac arrest, multiple VA-ECMO implantations due to vascular access changes, weaning failure, or ICU readmission. A statistical approach using inverse probability of treatment weighting was used to estimate the effect of the cannulation site on the outcomes. The primary endpoint was the 90-day mortality. The secondary endpoints were vascular access complications, stroke, and other complications related to retrograde blood flow. Outcomes were estimated using logistic regression analysis. RESULTS: VA-ECMO was performed on 534 patients. Patients with refractory cardiac arrest (n = 77 (14%)) and those supported by multiple VA-ECMO (n = 92, (17%)) were excluded. Out of the 333 patients studied (n = 209 Vf-Aa; n = 124 VF-AF), the main indications for VA-ECMO implantation were post-cardiotomy (33%, n = 109), dilated cardiomyopathy (20%, n = 66), post-cardiac transplantation (15%, n = 50), acute myocardial infarction (14%, n = 46) and other etiologies (18%, n = 62). The median SOFA score was 9 [7-11], and the crude 90-day mortality rate was 53% (n = 175). After IPTW, the 90-day mortality was similar in the Vf-Aa and VF-AF groups (54% vs 58%, IPTW-OR = 0.84 [0.54-1.29]). Axillary artery cannulation was associated with significantly fewer local infections (OR = 0.21, 95% CI:0.09-0.51), limb ischemia (OR = 0.37, 95% CI:0.17-0.84), bowel ischemia (OR = 0.16, 95% CI:0.05-0.51) and pulmonary edema (OR = 0.52, 95% CI:0.29-0.92) episodes, but with a higher rate of stroke (OR = 2.87, 95% CI:1.08-7.62) than femoral artery cannulation. CONCLUSION: Compared to VF-AF, axillary cannulation was associated with similar 90-day mortality rates. The high rate of stroke associated with axillary artery cannulation requires further investigation.

Acute Kidney Injury and ECMO: Two Sides of the Same Coin.

How to cite this article: Gupta S, Tomar DS. Acute Kidney Injury and ECMO: Two Sides of the Same Coin. Indian J Crit Care Med 2024;28(1):3-4.

Veno-venous extra-corporeal membrane oxygenation in complex tracheobronchial resection.

Background: Elective extra-corporeal membrane oxygenation (ECMO) is rarely used in thoracic surgery, apart from lung transplantation. The purpose of this study was to summarize our institutional experience with the intraoperative use of veno-venous (VV) ECMO in selected cases of main airway surgery. Methods: We retrospectively analyzed the data of 10 patients who underwent main airway surgery with the support of VV-ECMO between June 2013 and August 2022. Results: Surgical procedures included: three carinal resection and reconstruction with complete preservation of the lung parenchyma, one right upper double-sleeve lobectomy and hemi-carinal resection, and one sleeve resection of the left main bronchus after previous right lower bilobectomy, for thoracic malignancies; four tracheal/carinal repair for extensive traumatic laceration; one extended tracheal resection due to post-tracheostomy stenosis in a patient who had previously undergone a left pneumonectomy. The median intraoperative VV-ECMO use was 162.5 minutes. In three cases with complex resection and reconstruction of the carina and in one case of extended post-tracheostomy stenosis and previous pneumonectomy, high-flow VV-ECMO allowed interruption of ventilation for almost 3 hours. In four patients, VV-ECMO was prolonged in the postoperative period to ensure early extubation. There were no perioperative deaths, no complications related to the use of ECMO and no intraoperative change in the planned type of ECMO. Significant complications occurred only in one patient who developed a small anastomotic dehiscence that led to stenosis and required placement of a Montgomery tube. At the median follow-up of 30 months, all 10 patients were still alive. Conclusions: The use of intraoperative VV-ECMO allows safe and precise performance of main airway surgery with minimal postoperative morbidity in patients requiring complex resections and reconstructions and in cases that cannot be managed with conventional ventilation techniques.

Lung biopsies in infants and children in critical care situation.

INTRODUCTION: Lung biopsy is considered as the last step investigation for diagnosing lung diseases; however, its indication must be carefully balanced with its invasiveness. The present study aims to evaluate the diagnostic yield of lung biopsy in critically ill patients hospitalized in the pediatric intensive care unit (ICU). MATERIAL AND METHODS: Children who underwent a lung biopsy in the ICU between 1995 and 2022 were included. Biopsies performed in the operating room and post-mortem biopsies were excluded. RESULTS: Thirty-one patients were included, with a median age of 18 days (2 days to 10.8 years); 21 (67.7%) were newborns. All patients required invasive mechanical ventilation, 26 (89.7%) had a pulmonary hypertension, and 22 (70.9%) were placed under extracorporeal membrane oxygenation (ECMO). The lung biopsy led to a diagnosis in 81% of the patients. The diagnostic reliability seemed to decrease with age (95% in newborns, 71% in 1 month to 2 years and 0/3 patients aged over 2 years old). Diffuse developmental disorders of the lung accounted for 15 (49%) patients, primarily alveolar capillary dysplasia, followed by surfactant disorders in 5 (16%) patients. Complications occurred in 9/31 (29%) patients including eight under ECMO, with massive hemorrhages in seven cases. DISCUSSION AND CONCLUSION: In critical situations, lung biopsy should be performed. Lung biopsy is a reliable diagnostic procedure for neonates in critical situation when a diffuse developmental disorder of the lung is suspected. The majority of lung biopsy complication was associated with the use of ECMO. The prospective evaluation of the complications of such procedure under ECMO, and particularly over 10 days of ECMO and in children over 2-year-old remains to be ascertained.

Multiple thromboses, including intracardiac thrombi, accompanied by HIT during ECMO successfully treated with NOACs: A case report.

INTRODUCTION: Unfractionated heparin remains the mainstay of anticoagulation therapy during extracorporeal membrane oxygenation (ECMO) maintenance. However, its continued use in clinical practice exposes patients to the risk of developing heparin-induced thrombocytopenia (HIT). CASE REPORT: A 50-year-old male was diagnosed with multiple thromboses, including an intracardiac thrombi, accompanied by HIT during ECMO after cardiogenic shock related to acute myocardial infarction. The patient was successfully treated with new oral anticoagulants (NOAC), without significant complications. DISCUSSION: HIT during ECMO resulting in multiple thromboses is rare. To our knowledge, this is the first reported case of NOAC use in this context. CONCLUSION: Although thrombocytopenia and thrombosis can occur for various reasons during ECMO maintenance, it is important to consider HIT as a potential cause. NOACs can be considered as a therapeutic option.

Pediatric surgical interventions on ECMO.

Extra Corporeal Membrane Oxygenation (ECMO) has historically been reserved for refractory pulmonary and cardiac support in children and adult. Operative intervention on ECMO was traditionally contraindicated due to hemorrhagic complications exacerbated by critical illness and anticoagulation needs. With advancements in ECMO circuitry and anticoagulation strategies operative procedures during ECMO have become feasible with minimal hemorrhagic risks. Here we review anticoagulation and operative intervention considerations in the pediatric population during ECMO cannulation. Pediatric surgical interventions currently described in the literature while on ECMO support include thoracotomy/thoracoscopy, tracheostomy, laparotomy, and injury related procedures i.e. wound debridement. A patient should not be precluded from a surgical intervention while on ECMO, if the surgery is indicated.

Safety of inter-facility transport strategies for patients referred for severe acute respiratory distress syndrome.

BACKGROUND: Inter-facility transport of patients with acute respiratory distress syndrome (ARDS) in the prone position (PP) is a high-risk situation, compared to other strategies. We aimed to quantify the prevalence of complications during transport in PP, compared to transports with veno-venous extracorporeal membrane oxygenation (VV-ECMO) or in the supine position (SP). METHODS: We performed a retrospective, single center cohort study in Lyon university hospital, France. We included patients ≥ 16 years with ARDS (Berlin definition) transported to an ARDS referral center between 01/12/2016 and 31/12/2021. We compared patients transported in PP, to those transported in SP without VV-ECMO, and those transported with VV-ECMO (in SP), by a multidisciplinary and specialized medical transport team, including an emergency physician and an intensivist. The primary outcome was the rate of transport-related complications (hypoxemia, hypotension, cardiac arrest, cannula or tube dislodgement) in each study groups, compared using a Fisher test. RESULTS: One hundred thirty-four patients were enrolled (median PaO2/FiO2 70 [58-82] mmHg), of which 11 (8%) were transported in PP, 44 (33%) with VV-ECMO, and 79 (59%) in SP. The most frequent risk factor for ARDS in the PP group was bacterial pneumonitis, and viral pneumonitis in the other 2 groups. Transport-related complications occurred in 36% (n = 4) of transports in PP, compared to 39% (n = 30) in SP and 14% (n = 6) with VV-ECMO, respectively (p = 0.33). VV-ECMO implantation after transport was not different between SP and PP patients (n = 7, 64% vs. n = 31, 39%, p = 0.19). CONCLUSIONS: In the context of a specialized multi-disciplinary ARDS transport team, transport-related complication rates were similar between patients transported in PP and SP, while there was a trend of lower rates in patients transported with VV-ECMO.

Left atrium veno-arterial extra corporeal membrane oxygenation as temporary mechanical support for cardiogenic shock: A case report.

BACKGROUND: Veno-arterial extra corporeal membrane oxygenation (VA-ECMO) support is commonly complicated with left ventricle (LV) distension in patients with cardiogenic shock. We resolved this problem by transeptally converting VA-ECMO to left atrium veno-arterial (LAVA)-ECMO that functioned as a temporary paracorporeal left ventricular assist device to resolve LV distension. In our case LAVA-ECMO was also functioning as a bridge-to-transplant device, a technique that has been scarcely reported in the literature. CASE SUMMARY: A 65 year-old man suffered from acute myocardial injury that required percutaneous stents. Less than two weeks later, noncompliance to antiplatelet therapy led to stent thrombosis, cardiogenic shock, and cardiac arrest. Femoro-femoral VA-ECMO support was started, and the patient underwent a second coronary angiography with re-stenting and intra-aortic balloon pump placement. The VA-ECMO support was complicated by left ventricular distension which we resolved via LAVA-ECMO. Unfortunately, episodes of bleeding and sepsis complicated the clinical picture and the patient passed away 27 d after initiating VA-ECMO. CONCLUSION: This clinical case demonstrates that LAVA-ECMO is a viable strategy to unload the LV without another invasive percutaneous or surgical procedure. We also demonstrate that LAVA-ECMO can also be weaned to a left ventricular assist device system. A benefit of this technique is that the procedure is potentially reversible, should the patient require VA-ECMO support again. A transeptal LV venting approach like LAVA-ECMO may be indicated over ImpellaTM in cases where less LV unloading is required and where a restrictive myocardium could cause LV suctioning. Left ventricular over-distention is a well-known complication of peripheral VA-ECMO in cardiogenic shock and LAVA ECMO through transeptal cannulation offers a novel and safe approach for treating LV overloading, without the need of an additional percutaneous access.

Impact of Extra-Corporeal Membrane Oxygenation and Blood Purification Therapy on Early Mobilization in the Intensive Care Unit: Retrospective Cohort Study.

OBJECTIVE: To investigate the effect on early mobilization in patients undergoing extra-corporeal membrane oxygenation (ECMO) and acute blood purification therapy in the intensive care unit (ICU). METHODS: We conducted this multicenter retrospective cohort study by collecting data from six ICUs in Japan. Consecutive patients who were admitted to the ICU, aged ≥18 years, and received mechanical ventilation for >48 hours were eligible. The analyzed were divided into two groups: ECMO/blood purification or control group. Clinical outcomes; time to first mobilization, number of total ICU rehabilitations, mean and highest ICU mobility scale (IMS); and daily barrier changes were also investigated. RESULTS: A total of 204 patients were included in the analysis, 43 in the ECMO/blood purification group and 161 in the control group. In comparison of clinical outcome, the ECMO/blood purification group had a significantly longer time to first mobilization: ECMO/blood purification group 6 vs. control group 4 (p=0.003), higher number of total ICU rehabilitations: 6 vs. 5 (p=0.042), lower mean: 0 vs. 1 (p=0.043) and highest IMS: 2 vs. 3 (p=0.039) during ICU stay. Circulatory factor were most frequently described as barriers to early mobilization on days 1 (51%), 2 (47%), and 3 (26%). On days 4 to 7, the most frequently described barrier was consciousness factors (21%, 16%, 19%, and 21%, respectively). CONCLUSION: The results of this study comparing the ECMO/blood purification group and the untreated group in the ICU showed that the ECMO/blood purification group had significantly longer days to mobilization and significantly lower mean and highest IMS.

Hemodynamic performance evaluation of neonatal ECMO double lumen cannula using fluid-structure interaction.

Extra corporeal membrane oxygenation (ECMO) is an artificial oxygenation facility, employed in situations of cardio-pulmonary failure. Some diseases i.e., acute respiratory distress syndrome, pulmonary hypertension, corona virus disease (COVID-19) etc. affect oxygenation performance of the lungs thus requiring the need of artificial oxygenation. Critical care teams used ECMO technique during the COVID-19 pandemic to support the heart and lungs of COVID-19 patients who had an acute respiratory or cardiac failure. Double Lumen Cannula (DLC) is one of the most critical components of ECMO as it resides inside the patient and, connects patient with external oxygenation circuit. DLC facilitates delivery and drainage of blood from the patient's body. DLC is characterized by delicate balance of internal and external flows inside a limited space of the right atrium (RA). An optimal performance of the DLC necessitates structural stability under biological and hemodynamic loads, a fact that has been overlooked by previously published studies. In the past, many researchers experimentally and computationally investigated the hemodynamic performance of DLC by employing Eulerian approach, which evaluate instantaneous blood damage without considering blood shear exposure history (qualitative assessment only). The present study is an attempt to address the aforementioned limitations of the previous studies by employing Lagrangian (quantitative assessment) and incorporating the effect of fluid-structure interaction (FSI) to study the hemodynamic performance of neonatal DLC. The study was performed by solving three-dimensional continuity, momentum, and structural mechanics equation(s) by numerical methods for the blood flow through neonatal DLC. A two-way coupled FSI analysis was performed to analyze the effect of DLC structural deformation on its hemodynamic performance. Results show that the return lumen was the most critical section with maximum pressure drop, velocity, shear stresses, and blood damage. Recirculation and residence time of blood in the right atrium (RA) increases with increasing blood flow rates. Considering the structural deformation has led to higher blood damage inside the DLC-atrium system. Maximum Von-Mises stress was present on the side edges of the return lumen that showed direct proportionality with the blood flow rate.

Venoarterial-extra corporeal membrane oxygenation-assisted parathyroidectomy for hypercalcemic crisis due to parathyroid carcinoma complicated by severe circulatory and respiratory failure: a case report.

BACKGROUND: Hypercalcemia crisis is a rare but severe form of hypercalcemia complicated by multiple organ failure. Hypercalcemia crisis due to hyperparathyroidism is commonly caused by a parathyroid tumor, which often requires surgical resection. However, there are no clear recommendations on when the surgery should be performed. CASE PRESENTATION: A 64-year-old female patient developed hyperparathyroidism due to a parathyroid tumor and hypercalcemic crisis, which was complicated by severe circulatory and respiratory failure refractory to medical therapy, and an emergent surgery was planned to resect the parathyroid tumor. To prevent intraoperative circulatory and respiratory collapse, venoarterial-extra corporeal membrane oxygenation (VA-ECMO) was introduced, resulting in a safe operation and anesthetic management. CONCLUSIONS: In patients with hypercalcemic crisis complicated by severe circulatory and respiratory failure, induction of prophylactic VA-ECMO was useful for safe anesthetic management. Surgical resection should be performed as soon as the diagnosis is made before VA-ECMO is required.

Withdrawing extra corporeal membrane oxygenation (ECMO) against a family's wishes: Three permissible scenarios.

The ethical permissibility of unilaterally withdrawing life-sustaining technologies has been a perennial topic in transplant and critical care medicine, often focusing on CPR and mechanical ventilation. The permissibility of unilateral withdrawal of extracorporeal membrane oxygenation (ECMO) has been discussed sparingly. When addressed, authors have appealed to professional authority rather than substantive ethical analysis. In this Perspective, we argue that there are at least three (3) scenarios wherein healthcare teams would be justified in unilaterally withdrawing ECMO, despite the objections of the patient's legal representative. The ethical considerations that provide the groundwork for these scenarios are, primarily: equity, integrity, and the moral equivalence between withholding and withdrawing medical technologies. First, we place equity in the context of crisis standards of medicine. After this, we discuss professional integrity as it relates to the innovative usage of medical technologies. Finally, we discuss the ethical consensus known at the "equivalence thesis." Each of these considerations include a scenario and justification for unilateral withdrawal. We also provide three (3) recommendations that aim at preventing these challenges at their outset. Our conclusions and recommendations are not meant to be blunt arguments that ECMO teams wield whenever disagreement about the propriety of continued ECMO support arises. Instead, the onus will be on individual ECMO programs to evaluate these arguments and decide if they represent sensible, correct, and implementable starting points for clinical practice guidelines or policies.

Outcomes with use of extra-corporeal membrane oxygenation in high-risk pulmonary embolism: a national database perspective.

High-risk pulmonary embolism (PE) patients can be managed with systemic lysis, catheter-based therapies, or surgical embolectomy. Despite the advent of newer therapies, patients with high-risk PE remain with a 50-60% short-term mortality risk. In such patients, extracorporeal membrane oxygenation (ECMO) is increasingly utilized for hemodynamic support. To evaluate the outcomes of the use of ECMO in patients with high-risk PE. Using the National Inpatient Sample (NIS) database, we identified patients with high-risk PE using ICD 10 codes and compared in-hospital outcomes of patients with and without ECMO support. We identified 38,035 patients with high-risk PE, of whom 820 had undergone ECMO placement. Most patients who underwent ECMO were male (54%), white (65%), and with a mean age of 53.7 years. ECMO use was not associated with a meaningful difference in patient mortality when comparing treatment groups (OR, 1.32 ± 0.39; 0.74-2.35; p = 0.35). Rather, ECMO use was associated with a higher frequency of inpatient complications. ECMO use was not associated with a significant difference in patient mortality in patients with high-risk PE.

Persistent Hypoxia After Blunt Thoracic Trauma due to Flail Tricuspid Valve Leaflet and Patent Foramen Ovale.

Structural cardiac injury after blunt trauma is uncommon but usually life-threatening. While tricuspid injury is very rare and potentially lethal, the right heart can accommodate larger volumes and higher pressures in acute tricuspid insufficiency and facilitate initial stabilization prior to definitive valvular repair. ECMO may be used to ameliorate resulting right heart failure. The traumatic force required to cause cardiac structural injury is also associated with pulmonary complications related to pneumothorax, hemothorax, effusion, acute pain secondary to rib fractures, and pulmonary contusions causing hypoxia. We present an unusual case of hypoxia in a trauma patient caused by acute tricuspid regurgitation with pre-existing patent foramen ovale.

Physiotherapy-led lung ultrasound in neonatal extra-corporeal membrane oxygenation: A case-study.

There is a growing body of evidence to support the use of point of care lung ultrasound (LUS) in adult patients receiving extra-corporeal membrane oxygenation (ECMO). However, literature supporting the use of LUS in neonatal and paediatric ECMO patients is limited. We report the use of physiotherapy-led LUS in a neonatal ECMO patient. The baby required veno-arterial ECMO for long-segment tracheal stenosis and presented with complete right lung collapse. In this situation real time, bedside imaging enabled timely and specific physiotherapy treatment to be implemented. LUS also allowed immediate reassessment and subsequent improvement to be determined. This negated the requirement for an additional, pre-surgery chest X-ray, reducing radiation exposure. This case-study highlights LUS as an important tool for health professionals caring for neonatal and paediatric ECMO patients. Future research should include further development of population specific LUS scoring systems.