Percutaneous Venopulmonary Extracorporeal Membrane Oxygenation as Bridge to Lung Transplantation

Mechanical circulatory support (MCS) as a bridge to lung transplant is an infrequent but accepted pathway in patients who have refractory end-stage pulmonary failure. The American Association of Thoracic Surgeons Expert Consensus Guidelines, published in 2023, recommends venovenous (VV) extracorporeal membrane oxygenation (ECMO) as the initial configuration for those patients who have failed conventional medical therapy, including mechanical ventilation, while waiting for lung transplantation and needing MCS. Alternatively, venoarterial (VA) ECMO can be used in patients with acute right ventricular failure, hemodynamic instability, or refractory respiratory failure. With the advancement in percutaneous venopulmonary (VP) ECMO cannulation techniques, this option is becoming an attractive configuration as bridge to lung transplantation. This configuration enhances stability of the right ventricle, prevents recirculation with direct introduction of pulmonary artery oxygenation, and promotes hemodynamic stability during mobility, rehabilitation, and sedation-weaning trials before lung transplantation. Here, we present a case series of eight percutaneous VP ECMO as bridge to lung transplant with all patients mobilized, awake, and successfully transplanted with survival to hospital discharge.

Extracorporeal Carbon Dioxide Removal to De-escalate Venovenous Extracorporeal Membrane Oxygenation in Severe COVID-19 Acute Respiratory Distress Syndrome

OBJECTIVES

In a subset of patients with COVID-19 acute respiratory distress syndrome (ARDS), there is a need for extracorporeal membrane oxygenation (ECMO) for pulmonary support. The primary extracorporeal support tool for severe COVID-19 ARDS is venovenous (VV) ECMO; however, after hypoxemic respiratory failure resolves, many patients experience refractory residual hypercarbic respiratory failure. Extracorporeal carbon dioxide removal (ECCO2R) for isolated hypercarbic type II respiratory failure can be used in select cases to deescalate patients from VV ECMO while the lung recovers the ability to exchange CO2. The objective of this study was to describe the authors' experience in using ECCO2R as a bridge from VV ECMO.

DESIGN

Hemolung Respiratory Assist System (RAS) is a commercially available (ECCO2R) device, and the United States Food and Drug Administration accelerated its use under its Emergency Use Authorization for the treatment of refractory hypercarbic respiratory failure in COVID-19-induced ARDS. This created an environment in which selected and targeted mechanical circulatory support therapy for refractory hypercarbic respiratory failure could be addressed. This retrospective study describes the application of Hemolung RAS as a VV ECMO deescalation platform to treat refractory hypercarbic respiratory failure after the resolution of hypoxemic COVID-19 ARDS.

SETTING

A quaternary-care academic medical center, single institution.

PARTICIPANTS

Patients with refractory hypercarbic respiratory failure after COVID-19 ARDS who were previously supported with VV ECMO.

MEASUREMENTS AND MAIN RESULTS

Twenty-one patients were placed on ECCO2R after VV ECMO for COVID-19 ARDS. Seventeen patients successfully were transitioned to ECCO2R and then decannulated; 3 patients required reescalation to VV ECMO secondary to hypercapnic respiratory failure, and 1 patient died while on ECCO2R. Five (23.8%) of the 21 patients were transitioned off of VV ECMO to ECCO2R, with a compliance of <20 (mL/cmH2O). Of these patients, 3 with low compliance were reescalated to VV ECMO.

CONCLUSIONS

Extracorporeal carbon dioxide removal can be used to continue supportive methods for patients with refractory type 2 hypercarbic respiratory failure after COVID-19 ARDS for patients previously on VV ECMO. Patients with low compliance have a higher rate of reescalation to VV ECMO.

ECMO in trauma care: What you need to know

ABSTRACT

Over the past 10 years, extracorporeal membrane oxygenation (ECMO) use in trauma patients has increased significantly. This includes adult and pediatric trauma patients and even combat casualties. Most ECMO applications are in a venovenous (VV ECMO) configuration for acute hypoxemic respiratory failure or anatomic injuries that require pneumonectomy or extreme lung rest in a patient with insufficient respiratory reserve. In this narrative review, we summarize the most common indications for VV ECMO and other forms of ECMO support used in critically injured patients, underscore the importance of early ECMO consultation or regional referral, review the technical aspects of ECMO cannulation and management, and examine the expected outcomes for these patients. In addition, we evaluate the data where it exists to try to debunk some common myths surrounding ECMO management.

Adjunct Use of Continuous Renal Replacement Therapy with Extracorporeal Membrane Oxygenation Achieves Negative Fluid Balance and Enhances Oxygenation Which Improves Survival in Critically Ill Patients without Kidney Failure

INTRODUCTION

Fluid overload in extracorporeal membrane oxygenation (ECMO) patients has been associated with increased mortality. Patients receiving ECMO and continuous renal replacement therapy (CRRT) who achieve a negative fluid balance have improved survival. Limited data exist on the use of CRRT solely for fluid management in ECMO patients.

METHODS

We performed a single-center retrospective review of 19 adult ECMO patients without significant renal dysfunction who received CRRT for fluid management. These patients were compared to a cohort of propensity-matched controls.

RESULTS

After 72 h, the treatment group had a fluid balance of -3840 mL versus + 425 mL (p ≤ 0.05). This lower fluid balance correlated with survival to discharge (odds ratio 2.54, 95% confidence interval 1.10-5.87). Improvement in the ratio of arterial oxygen content to fraction of inspired oxygen was also significantly higher in the CRRT group (102.4 vs. 0.7, p ≤ 0.05). We did not observe any significant difference in renal outcomes.

CONCLUSIONS

The use of CRRT for fluid management is effective and, when resulting in negative fluid balance, improves survival in adult ECMO patients without significant renal dysfunction.

A Case Report of Combat Blast Injury Requiring Combat Casualty Care, Far-Forward ECMO, Air Transport, and All Levels of Military Critical Care

We describe a 34-year-old soldier who sustained a blast injury in Syria resulting in tracheal 5 cm tracheal loss, cervical spine and cord injury with tetraplegia, multiple bilateral rib fractures, esophageal injury, traumatic brain injury, globe evisceration, and multiple extremity soft tissue and musculoskeletal injuries including a left tibia fracture with compartment syndrome. An emergent intubation of the transected trachea was performed in the field, and the patient was resuscitated with whole blood prehospital. During transport to the Role 2, the patient required cardiopulmonary resuscitation for cardiac arrest. On arrival, he underwent a resuscitative thoracotomy and received a massive transfusion exclusively with whole blood. A specialized critical care team transported the patient to the Role 3 hospital in Baghdad, and the DoD extracorporeal membrane oxygenation (ECMO) team was activated secondary to his unstable airway and severe hypoxia secondary to pulmonary blast injury. The casualty was cannulated in Baghdad approximately 40 hours after injury with bifemoral cannulae in a venovenous configuration. He was transported from Iraq to the U.S. Army Institute of Surgical Research Burn Center in San Antonio without issue. Extracorporeal membrane oxygenation support was successfully weaned, and he was decannulated on ECMO day 4. The early and en route use of venovenous ECMO allowed for maintenance of respiratory support during transport and bridge to operative management and demonstrates the feasibility of prolonged ECMO transport in critically ill combat casualties.

Evolution of the United States Military Extracorporeal Membrane Oxygenation Transport Team

INTRODUCTION

The use of extracorporeal membrane oxygenation (ECMO) for the care of critically ill adult patients has increased over the past decade. It has been utilized in more austere locations, to include combat wounded. The U.S. military established the Acute Lung Rescue Team in 2005 to transport and care for patients unable to be managed by standard medical evacuation resources. In 2012, the U.S. military expanded upon this capacity, establishing an ECMO program at Brooke Army Medical Center. To maintain currency, the program treats both military and civilian patients.

MATERIALS AND METHODS

We conducted a single-center retrospective review of all patients transported by the sole U.S. military ECMO program from September 2012 to December 2019. We analyzed basic demographic data, ECMO indication, transport distance range, survival to decannulation and discharge, and programmatic growth.

RESULTS

The U.S. military ECMO team conducted 110 ECMO transports. Of these, 88 patients (80%) were transported to our facility and 81 (73.6%) were cannulated for ECMO by our team prior to transport. The primary indication for ECMO was respiratory failure (76%). The range of transport distance was 6.5 to 8,451 miles (median air transport distance = 1,328 miles, median ground transport distance = 16 miles). In patients who were cannulated remotely, survival to decannulation was 76% and survival to discharge was 73.3%.

CONCLUSIONS

Utilization of the U.S. military ECMO team has increased exponentially since January 2017. With an increased tempo of transport operations and distance of critical care transport, survival to decannulation and discharge rates exceed national benchmarks as described in ELSO published data. The ability to cannulate patients in remote locations and provide critical care transport to a military medical treatment facility has allowed the U.S. military to maintain readiness of a critical medical asset.

Morbid obesity is not a contraindication to transport on extracorporeal support

OBJECTIVES

Extracorporeal membrane oxygenation (ECMO) transport has not been described in morbidly obese patients, a population that can pose significant challenges in obtaining vascular access, indexed flows and transport logistics. We sought to study the feasibility and safety of transporting obese and morbidly obese patients during extracorporeal support.

METHODS

We conducted a retrospective review of all patients transported to our institution while receiving ECMO from September 2008 to September 2016. Survival to decannulation and survival to discharge were the primary outcomes. Obesity and morbid obesity were defined as a body mass index of greater than 30 kg/m2 and greater than 40 kg/m2, respectively.

RESULTS

From 2008 to 2016, 222 patients were transported to our institution while receiving ECMO. Among these included patients, 131 were non-obese (interquartile range 22-27 kg/m2), 63 were obese (interquartile range 31-35 kg/m2) and 28 were morbidly obese (interquartile range 41-49 kg/m2), with 6 patients having a body mass index greater than 50 kg/m2 (range 52.3-79 kg/m2). Pre-ECMO arterial blood gases, disease severity indices, cannulation strategies and transport distances were similar between these 3 groups. There was no mortality of patients during transport, and survival to discharge was 66% (n = 87) in non-obese patients, 56% (n = 35) in obese patients and 82% (n = 23) in morbidly obese patients (P = 0.042). On multivariable logistic regression analysis, body mass index was not a predictor of in-hospital mortality (odds ratio 0.99, 95% confidence interval 0.95-1.03; P = 0.517).

CONCLUSIONS

Transport of morbidly obese patients receiving ECMO may be performed safely and with excellent results in the setting of a dedicated ECMO transport programme with well-established management protocols.

Outcomes and Mortality Prediction Model of Critically Ill Adults With Acute Respiratory Failure and Interstitial Lung Disease

BACKGROUND

We aimed to examine short- and long-term mortality in a mixed population of patients with interstitial lung disease (ILD) with acute respiratory failure, and to identify those at lower vs higher risk of in-hospital death.

METHODS

We conducted a single-center retrospective cohort study of 126 consecutive adults with ILD admitted to an ICU for respiratory failure at a tertiary care hospital between 2010 and 2014 and who did not undergo lung transplantation during their hospitalization. We examined associations of ICU-day 1 characteristics with in-hospital and 1-year mortality, using Poisson regression, and examined survival using Kaplan-Meier curves. We created a risk score for in-hospital mortality, using a model developed with penalized regression.

RESULTS

In-hospital mortality was 66%, and 1-year mortality was 80%. Those with connective tissue disease-related ILD had better short-term and long-term mortality compared with unclassifiable ILD (adjusted relative risk, 0.6; 95% CI, 0.3-0.9; and relative risk, 0.6; 95% CI, 0.4-0.9, respectively). Our prediction model includes male sex, interstitial pulmonary fibrosis diagnosis, use of invasive mechanical ventilation and/or extracorporeal life support, no ambulation within 24 h of ICU admission, BMI, and Simplified Acute Physiology Score-II. The optimism-corrected C-statistic was 0.73, and model calibration was excellent (P = .99). In-hospital mortality rates for the low-, moderate-, and high-risk groups were 33%, 65%, and 96%, respectively.

CONCLUSIONS

We created a risk score that classifies patients with ILD with acute respiratory failure from low to high risk for in-hospital mortality. The score could aid providers in counseling these patients and their families.

Functional vascularized lung grafts for lung bioengineering

End-stage lung disease is the third leading cause of death worldwide, accounting for 400,000 deaths per year in the United States alone. To reduce the morbidity and mortality associated with lung disease, new therapeutic strategies aimed at promoting lung repair and increasing the number of donor lungs available for transplantation are being explored. Because of the extreme complexity of this organ, previous attempts at bioengineering functional lungs from fully decellularized or synthetic scaffolds lacking functional vasculature have been largely unsuccessful. An intact vascular network is critical not only for maintaining the blood-gas barrier and allowing for proper graft function but also for supporting the regenerative cells. We therefore developed an airway-specific approach to removing the pulmonary epithelium, while maintaining the viability and function of the vascular endothelium, using a rat model. The resulting vascularized lung grafts supported the attachment and growth of human adult pulmonary cells and stem cell-derived lung-specified epithelial cells. We propose that de-epithelialization of the lung with preservation of intact vasculature could facilitate cell therapy of pulmonary epithelium and enable bioengineering of functional lungs for transplantation.

Awake Extracorporeal Membrane Oxygenation as Bridge to Lung Transplantation: A 9-Year Experience

BACKGROUND

Extracorporeal membrane oxygenation (ECMO) is used as a bridge to lung transplantation, but characteristics that influence its success are poorly understood. This large, single-center experience evaluated the implementation and outcomes of ECMO in this setting.

METHODS

Data were collected for patients at our institution (New York-Presbyterian Hospital/Columbia University Medical Center in New York) who received ECMO as a bridge to lung transplantation from January 1, 2007 through July 10, 2016. Data were analyzed for demographics, baseline characteristics, survival, and ECMO configuration.

RESULTS

Seventy-two patients received ECMO as a bridge to lung transplantation. Of the 72 patients, 40 (55.6%) underwent the transplantation procedure, 37 (92.5%) survived to discharge, and 21 (84.0%) survived for 2 years. Inotropy or vasopressor support (70% vs 93.8%; p = 0.011), Simplified Acute Physiology Score (26.8 vs 30.5; p = 0.048), and ambulation (80% vs 56.2%; p = 0.030) were significantly different between the patients who underwent lung transplantation and those who did not. Patients with cystic fibrosis were more likely to have a bridge to transplantation than patients with other lung diseases (47.5% vs 25%; p = 0.050). Daily participation in physical therapy was achieved in 50 patients (69.4%).

CONCLUSIONS

This study demonstrated favorable survival in patients receiving ECMO as a bridge to lung transplantation and achieved high rates of physical therapy and avoidance of mechanical ventilation while ECMO was used in patients awaiting lung transplantation. With more than half of these patients successfully bridged to lung transplantation, we gained insight into the factors influencing patients' outcomes, including patient selection, timing of ECMO, and patient management.

Chronic thromboembolic pulmonary hypertension, pregnancy, and a pulmonary endarterectomy: a rare challenge

It is well described that patients with group 1 forms of pulmonary arterial hypertension have a high risk of mortality during pregnancy and in the early postpartum period. However, to the authors' knowledge, the diagnosis and management of group 4 pulmonary hypertension due to chronic thromboembolic pulmonary hypertension (CTEPH) during pregnancy with early postpartum pulmonary endarterectomy (PEA) has not been previously reported. We report the case of a 28-year-old woman who received a diagnosis of CTEPH during her pregnancy, was managed as an inpatient by a multidisciplinary team throughout the pregnancy and early postpartum period, and underwent PEA 6 weeks after delivery. While the management of acute pulmonary embolus in pregnancy is well described, this unique case of CTEPH diagnosed during pregnancy illustrates several challenging management issues.

Extracorporeal membrane oxygenation in the management of diffuse alveolar hemorrhage

Extracorporeal membrane oxygenation (ECMO) may be used to support patients with severe hypoxemic respiratory failure refractory to conventional mechanical ventilation. However, because systemic anticoagulation is generally required to maintain circuit patency, severe bleeding is often seen as a contraindication to ECMO. We describe our center's experience with four patients who received ECMO for refractory hypoxemic respiratory failure due to diffuse alveolar hemorrhage (DAH), a condition for which anticoagulation is typically contraindicated, and provide a review of the literature. The mean age was 35.8 ± 16.4 years. The mean pre-ECMO PaO2 to FIO2 ratio was 52.3 ± 9.4 mm Hg. All patients were treated with continuous infusions of heparin with a goal-activated partial thromboplastin time between 40 and 60 seconds (mean, 47.4 ± 11.6 seconds). All four subjects (100%) survived to decannulation, and three subjects (75%) survived to discharge. The results from this case series, along with previously published data, suggest that ECMO is a reasonable management option for patients with DAH-associated severe, refractory hypoxemic respiratory failure. This is especially true in the era of modern ECMO technology where lower levels of anticoagulation are able to maintain circuit patency while minimizing bleeding risk.

One Hundred Transports on Extracorporeal Support to an Extracorporeal Membrane Oxygenation Center

BACKGROUND

Extracorporeal life support technology has gained acceptance as a salvage mode for patients in respiratory or cardiac failure. Patients who are sick enough to require extracorporeal membrane oxygenation (ECMO) support are often too unstable for transfer to a hospital with ECMO capabilities. We highlight the progressive development of an ECMO transport team and the manner in which it provides reliable transport with excellent outcomes.

METHODS

All data were collected retrospectively from our hospital's electronic medical record. Patient outcomes are reported through April 2, 2014.

RESULTS

Our institution began an ECMO transport program in 2008, with the initial phase involving transport of highly selected patients for short distances. With experience we refined our intake and evaluation process. We also consolidated care for ECMO patients into two intensive care units and developed a dedicated ECMO intensivist position. As the program has matured, patient selection has become more inclusive and we have extended our capabilities to include interstate and international transport. All 100 patients were successfully placed on ECMO and transported to our center. Seventy-nine patients were placed on venovenous ECMO, 19 on venoarterial ECMO, and 2 on venovenous arterial ECMO. The median transport distance was 16 miles and ranged from 2.5 to 7,084 miles.

CONCLUSIONS

Extracorporeal membrane oxygenation transport can be performed safely and reliably with excellent outcomes with a dedicated team that maintains stringent adherence to well-designed management protocols.

Extracorporeal membrane oxygenation transport after traumatic aortic valve injury

Traumatic injury to the aortic valve is an uncommon clinical entity. Rarer still is the transport of such a patient using extracorporeal membrane oxygenation (ECMO) to a specialized ECMO center for definitive repair. We present a case of traumatic rupture of the aortic valve complicated by severe acute respiratory distress syndrome with interhospital transport using ECMO and subsequent aortic valve replacement.

The "sport model": extracorporeal membrane oxygenation using the subclavian artery

Venoarterial extracorporeal membrane oxygenation is used for patients with refractory cardiopulmonary failure. Arterial cannulation by means of femoral arteries is fraught with potential complications. We present a technique for subclavian artery cannulation to provide a safe and durable means of venoarterial extracorporeal membrane oxygenation support.

Extracorporeal membrane oxygenation use in patients with traumatic brain injury

Venovenous extracorporeal membrane oxygenation (ECMO) is used for patients with severe, potentially reversible, respiratory failure unresponsive to conventional management. It is relatively contraindicated in patients with traumatic brain injury (TBI) due to bleeding complications and use of anticoagulation. We report two cases of TBI patients treated with ECMO.

Hypothalamic-pituitary-adrenal axis activity and its relationship to the autonomic nervous system in women with visceral and subcutaneous obesity: effects of the corticotropin-releasing factor/arginine-vasopressin test and of stress

In a previous study, we demonstrated that premenopausal women with visceral obesity have hyperactivity of the hypothalamic-pituitary-adrenal (HPA) axis, characterized by an exaggerated hormone response to corticotropin-releasing factor (CRF) and corticotropin (ACTH) stimulation. The hypothalamic peptide flow that stimulates the pituitary, particularly after a physiological stress challenge, involves not only CRF, but also arginine-vasopressin (AVP), which synergizes the CRF capacity to stimulate pituitary hormone secretion. Previous studies in humans have demonstrated that combining AVP with CRF permits maximal stimulation of the pituitary, providing a more appropriate method of assessing pituitary hormone reserve. We therefore investigated the response of the HPA axis to combined CRF and AVP stimuli in obese women with different obesity phenotypes. Moreover, we examined hormonal and cardiovascular responses to several mental stress tasks, according to previously standardized procedures. Two groups of age-matched premenopausal eumenorrheic obese women with visceral (V-BFD) or subcutaneous (S-BFD) body fat distribution and a group of normal-weight healthy controls were investigated. All women randomly underwent the following protocol: (1) a combined CRF/AVP test (100 micrograms plus 0.3 IU intravenously [IV], respectively); (2) a standardized stress test, which consisted of completing two puzzles and a mental arithmetic test; and (3) a control saline test. Blood samples for ACTH and cortisol determinations were obtained before and during each test, and measurements of arterial blood pressure and pulse rate were made at regular intervals during the stress test. After combined CRF/AVP administration, ACTH and cortisol were significantly higher in V-BFD than in the other two groups. In contrast, no significant hormonal variation was found in either group during stress tasks. During the stress test, pulse rate (but not arterial blood pressure) significantly increased after 8 and 15 minutes in the V-BFD group, whereas no significant variation was found in S-BFD and control women. A significant correlation was present between the pulse rate and change in cortisol level during the stress test at minutes 8 (r=.54, P<.05) and 15 (r=.57, p<.01) in all women considered together. Subjective emotional involvement during stressful tasks was measured by a two-dimensional short verbal scale, which revealed that the stress section had a more significant impact in obese V-BFD than in S-BFD and control women. These data therefore confirm that women with visceral obesity have hyperactivity of the HPA axis, and that the combined CRF/AVP stimulation may offer a good tool for investigating pituitary reserve in this obesity phenotype. Moreover, the results indicate that these women probably have a hyperreactive sympathetic response to acute stress that seems interrelated to that of the HPA axis.

Insulin regulates testosterone and sex hormone-binding globulin concentrations in adult normal weight and obese men

There are no studies in vivo on the effects of insulin on androgens and sex hormone-binding globulin (SHBG) in men. We, therefore, investigated the effects of insulin suppression on testosterone and SHBG in two groups of eight nondiabetic adult obese men and six healthy normal weight men who underwent diazoxide treatment (100 mg, three times daily) for 7 days. Blood samples for hormone determination were obtained before the subjects had been selected for the study, immediately before diazoxide administration, and on the last day of treatment. A 24-h oral glucose tolerance test was also performed for glucose, insulin, and C-peptide determinations before and on the last day of treatment. Only one subject experienced significant side-effects, and no significant changes in mean body weight were found during the treatment. Diazoxide administration worsened glucose tolerance in several subjects and reduced fasting and glucose-stimulated insulin levels by approximately 50% in both control and obese subjects. No significant difference was present between historical and pretreatment hormone values in either group. Moreover, there were no differences in pretreatment gonadotropin and SHBG concentrations between the two groups, whereas testosterone (free and total) levels were lower in the obese than in the control subjects. After diazoxide administration, testosterone (free and total) decreased slightly, but significantly, whereas LH and SHBG significantly increased in both groups. Diazoxide treatment increased estradiol levels in controls, but not in obese men. In conclusion, these results indicate that in vivo, insulin is capable of stimulating testosterone production and, simultaneously, of inhibiting SHBG concentrations in both normal weight and obese men.