Interventional Lung Assist: A New Concept of Protective Ventilation in Bridge to Lung Transplantation

Pumpless arteriovenous extracorporeal membrane oxygenation: A novel mode of respiratory support in a lamb model of congenital diaphragmatic hernia

BACKGROUND

Extracorporeal membrane oxygenation (ECMO) is commonly required in neonates with congenital diaphragmatic hernia (CDH) complicated by pulmonary hypertension (PH). ECMO carries significant risk, and is contraindicated in the setting of extreme prematurity or intracranial hemorrhage. Pumpless arteriovenous ECMO (P-ECMO) may represent an alternative for respiratory support. The present study summarizes our initial experience with P-ECMO in a lamb model of CDH.

STUDY DESIGN

Surgical creation of CDH was performed at 65-75days' gestation. At term (135-145days), lambs were delivered into the P-ECMO circuit. Three animals were maintained on a low-heparin infusion protocol (target ACT 160-180) and three animals were maintained with no systemic heparinization.

RESULTS

Animals were supported by the circuit for 380.7 +/- 145.6h (range, 102-504h). Circuit flow rates ranged from 97 to 208ml/kg/min, with adequacy of organ perfusion demonstrated by stable serum lactate levels (3.0 +/- 1.7) and pH (7.4 +/- 0.3). Necropsy demonstrated no evidence of thrombogenic complications.

CONCLUSION

Pumpless extracorporeal membrane oxygenation achieved support of CDH model lambs for up to three weeks. This therapy has the potential to bridge neonates with decompensated respiratory failure to CDH repair with no requirement for systemic anticoagulation, and may be applicable to patients currently precluded from conventional ECMO support.

Paracorporeal Lung Devices: Thinking Outside the Box

Extracorporeal Membrane Oxygenation (ECMO) is a resource intensive, life-preserving support system that has seen ever-expanding clinical indications as technology and collective experience has matured. Clinicians caring for patients who develop pulmonary failure secondary to cardiac failure can find themselves in unique situations where traditional ECMO may not be the ideal clinical solution. Existing paracorporeal ventricular assist device (VAD) technology or unique patient physiologies offer the opportunity for thinking "outside the box." Hybrid ECMO approaches include splicing oxygenators into paracorporeal VAD systems and alternative cannulation strategies to provide a staged approach to transition a patient from ECMO to a VAD. Alternative technologies include the adaptation of ECMO and extracorporeal CO₂ removal systems for specific physiologies and pediatric aged patients. This chapter will focus on: (1) hybrid and alternative approaches to extracorporeal support for pulmonary failure, (2) patient selection and, (3) technical considerations of these therapies. By examining the successes and challenges of the relatively select patients treated with these approaches, we hope to spur appropriate research and development to expand the clinical armamentarium of extracorporeal technology.

Single-Site Cannulation Venovenous Extracorporeal CO2 Removal as Bridge to Lung Volume Reduction Surgery in End-Stage Lung Emphysema

Lung volume reduction surgery (LVRS) is an important treatment option for end-stage lung emphysema in carefully selected patients. Here, we first describe the application of low-flow venovenous extracorporeal CO2 removal (LFVV-ECCO2R) as bridge to LVRS in patients with end-stage lung emphysema experiencing severe hypercapnia caused by acute failure of the breathing pump. Between March and October 2015, n = 4 patients received single-site LFVV-ECCO2R as bridge to LVRS. Indication for extracorporeal lung support was severe hypercapnia with respiratory acidosis and acute breathing pump failure. Two patients required continuous mechanical ventilation over a temporary tracheostomy and were bed ridden. The other two patients were nearly immobile because of severe dyspnea at rest. Length of preoperative ECCO2R was 14 (1-42) days. All patients underwent unilateral LVRS. Anatomical resection of the right (n = 3) or left (n = 1) upper lobe was performed. Postoperatively, both patients with previous mechanical ventilatory support were successfully weaned. ECCO2R in patients with end-stage lung emphysema experiencing severe hypercapnia caused by acute breathing pump failure is a safe and effective bridging tool to LVRS. In such patients, radical surgery leads to a significant improvement of the performance status and furthermore facilitates respiratory weaning from mechanical ventilation.

Successful Rescue Therapy with Pumpless Extracorporeal Carbon Dioxide Removal in a Patient with Persistent Air Leakage due to Empyema

A young metastatic lung cancer patient developed empyema due to an infection with carbapenem-resistant Acinetobacter baumannii. Hydropneumothorax was detected and managed by a tube thoracotomy. However, persistent air leakage through the chest tube was observed due to the presence of a bronchopleural fistula (BPF). As hypercapnic respiratory failure had progressed and the large air leak did not diminish by conservative management, a pumpless extracorporeal lung assist (pECLA) device was inserted. The pECLA allowed the patient to be weaned from mechanical ventilation and the BPF to heal. The present case shows the effective application of pECLA in a patient with empyema complicated with BPF and severe hypercapnic respiratory failure. pECLA enabled us to minimize airway pressure to aid in the closure of the BPF in the mechanically ventilated patient.

Clinical Outcomes of Heart-Lung Transplantation: Review of 10 Single-Center Consecutive Patients

BACKGROUND

Heart-lung transplantation (HLT) has provided hope to patients with end-stage lung disease and irreversible heart dysfunction. We reviewed the clinical outcomes of 10 patients who underwent heart-lung transplantation at Asan Medical Center.

METHODS

Between July 2010 and August 2014, a total of 11 patients underwent HLT at Asan Medical Center. After excluding one patient who underwent concomitant liver transplantation, 10 patients were enrolled in our study. We reviewed the demographics of the donors and the recipients' baseline information, survival rate, cause of death, and postoperative complications. All patients underwent follow-up, with a mean duration of 26.1±16.7 months.

RESULTS

Early death occurred in two patients (20%) due to septic shock. Late death occurred in three patients (38%) due to bronchiolitis obliterans (n=2) and septic shock (n=1), although these patients survived for 22, 28, and 42 months, respectively. The actuarial survival rates at one year, two years, and three years after HLT were 80%, 67%, and 53%, respectively.

CONCLUSION

HLT is a procedure that is rarely performed in Korea, even in medical centers with large heart and lung transplant programs. In order to achieve acceptable clinical outcomes, it is critical to carefully choose the donor and the recipient and to be certain that all aspects of the transplant procedure are planned in advance with the greatest care.

Veno-venous extracorporeal membrane oxygenation support during lung volume reduction surgery for a severe respiratory failure patient with emphysema

The use of extracorporeal membrane oxygenation (ECMO) in adults has increased in popularity and importance for the support of patients with cardiac or pulmonary failure, but rarely been described as a means of support during anaesthesia and surgery. We report the case of a patient who required lung volume reduction because of emphysema where veno-venous ECMO was required both during surgery and for the first four days postoperatively. We describe the anaesthetic management of this patient who had severe respiratory failure, review other alternatives and discuss why ECMO was particularly suited to this case.

Partial extracorporeal carbon dioxide removal using a standard continuous renal replacement therapy device: a preliminary study

To test the feasibility, safety, and efficacy of partial extracorporeal CO2 removal (PECCO2R) using a standard continuous renal replacement (CRRT) device with a pediatric oxygenation membrane introduced into the circuit in a serial manner. In this retrospective single-center study, we have studied mechanically ventilated patients with persistent significant respiratory acidosis and acute renal failure requiring ongoing CRRT. Sixteen patients were treated with our PECCO2R device. PaCO2 and arterial pH were measured before as well as at 6 and 12 hours after PECCO2R implementation. Hemodynamic parameters were continuously monitored. Our PECCO2R system was efficient to significantly reduce PaCO2 and increase arterial pH. The median PaCO2 before treatment was 77 mm Hg (59-112) with a median reduction of 24 mm Hg after 6 hours and 30 mm Hg after 12 hours (31% and 39%, respectively). The median pH increase was 0.16 at 6 hours and 0.23 at 12 hours. Partial extracorporeal CO2 removal treatment had no effect on oxygenation. No complication was observed. Our PECCO2R approach based on the simple introduction of a pediatric extracorporeal membrane oxygenation membrane into the circuit of a standard CRRT device is easy to implement, safe, and efficient to improve respiratory acidosis.

Impact of extracorporeal membrane oxygenation or mechanical ventilation as bridge to combined heart-lung transplantation on short-term and long-term survival

BACKGROUND

Extracorporeal membrane oxygenation (ECMO) and mechanical ventilation (MV) can be used as a bridge to heart-lung transplantation (HLT). The goal of this study was to determine if pretransplantation ECMO or MV affects survival in HLT.

METHODS

The United Network for Organ Sharing database was reviewed for all adult patients receiving HLT from 1995 to 2011. The primary outcome measured was risk-adjusted all cause mortality.

RESULTS

There were 542 adult patients received HLT during the study period. Of these, 15 (2.8%) required ECMO and 22 (4.1%) required MV as a bridge to transplantation. The groups were evenly matched with regards to recipient age, recipient gender, ischemic time, donor age, and donor gender. The ECMO cohort had worse survival than the control group at 30 days (20.0% vs. 83.5%) and 5 years (20.0% vs. 47.4%; P<0.001). When compared with control, patients requiring MV had worse survival at 1 month (77.3% vs. 83.5%) and 5 years (26.5% vs. 47.4%; P<0.001). The use of ECMO (hazard ratio [HR]=3.820, 95% confidence interval [CI]=1.600-9.116; P=0.003) or MV (HR=2.011, 95% CI=1.069-3.784; P=0.030) as a bridge to transplantation was independently associated with mortality on multivariate analysis. Recipient female gender was associated with survival (HR=0.754, 95% CI=0.570-0.998; P=0.048).

CONCLUSIONS

HLT recipients bridged by MV or ECMO have increased short-term and long-term mortality. Further studies are needed to optimize survival in these high-risk patients.

Advances in therapy for acute lung injury

Despite advances in the therapy for acute lung injury and adult respiratory distress syndrome, mortality remains high. The iatrogenic risk of ventilator-induced lung injury might contribute to this high mortality because the lungs are hyperinflated. Low tidal volume and inspiratory pressure are surrogates for the stress and strain concept; but lung compliance, transpulmonary pressure, and chest wall elastance might differ in individual patients. In previous published studies, an increasing number of patients were treated successfully with extracorporeal support. Extracorporeal membrane oxygenation and interventional lung assist allow ultraprotective ventilation strategies. However, these assists have different technical aspects and different indications.

Artificial lung basics: fundamental challenges, alternative designs and future innovations

There exists a growing demand for new technology that can take over the function of the human lung, from assisting an injured or recently transplanted lung to completely replacing the native organ. Many obstacles must be overcome to achieve the lofty goals and expectations of such a device. An artificial lung must be able to sustain the gas exchange requirements of a normal functioning lung. Pursuant to this purpose, the device must maintain appropriate blood pressure, decrease injury to blood cells and minimize clotting and immunologic response. Attachment methods vary, and ideally researchers want to find a way that minimizes bodily trauma, maximizes gas exchange and utilizes the inherent properties of the native lung. The currently proposed methods include the parallel, in-series and venous double-lumen cannula configurations. For the time being, current research focuses on the extracorporeal (i.e., outside the body) placement, but ultimate long-term goals look toward total implantation.

Extracorporeal life support for management of refractory cardiac or respiratory failure: initial experience in a tertiary centre

Introduction

Extracorporeal Life Support (ECLS) and extracorporeal membrane oxygenation (ECMO) have been indicated as treatment for acute respiratory and/or cardiac failure. Here we describe our first year experience of in-hospital ECLS activity, the operative algorithm and the protocol for centralization of adult patients from district hospitals.

Methods

At a tertiary referral trauma center (Careggi Teaching Hospital, Florence, Italy), an ECLS program was developed from 2008 by the Emergency Department and Heart and Vessel Department ICUs. The ECLS team consists of an intensivist, a cardiac surgeon, a cardiologist and a perfusionist, all trained in ECLS technique. ECMO support was applied in case of severe acute respiratory distress syndrome (ARDS) not responsive to conventional treatments. The use of veno-arterial (V-A) ECLS for cardiac support was reserved for cases of cardiac shock refractory to standard treatment and cardiac arrests not responding to conventional resuscitation.

Results

A total of 21 patients were treated with ECLS during the first year of activity. Among them, 13 received ECMO for ARDS (5 H1N1-virus related), with a 62% survival. In one case of post-traumatic ARDS, V-A ECLS support permitted multiple organ donation after cerebral death was confirmed. Patients treated with V-A ECLS due to cardiogenic shock (N = 4) had a survival rate of 50%. No patients on V-A ECLS support after cardiac arrest survived (N = 4).

Conclusions

In our centre, an ECLS Service was instituted over a relatively limited period of time. A strict collaboration between different specialists can be regarded as a key feature to efficiently implement the process.

Should lung transplantation be performed for patients on mechanical respiratory support? The US experience

OBJECTIVE

The study objectives were to (1) compare survival after lung transplantation in patients requiring pretransplant mechanical ventilation or extracorporeal membrane oxygenation with that of patients not requiring mechanical support and (2) identify risk factors for mortality.

METHODS

Data were obtained from the United Network for Organ Sharing for lung transplantation from October 1987 to January 2008. A total of 15,934 primary transplants were performed: 586 in patients on mechanical ventilation and 51 in patients on extracorporeal membrane oxygenation. Differences between nonsupport patients and those on mechanical ventilation or extracorporeal membrane oxygenation support were expressed as 2 propensity scores for use in comparing risk-adjusted survival.

RESULTS

Unadjusted survival at 1, 6, 12, and 24 months was 83%, 67%, 62%, and 57% for mechanical ventilation, respectively; 72%, 53%, 50%, and 45% for extracorporeal membrane oxygenation, respectively; and 93%, 85%, 79%, and 70% for unsupported patients, respectively (P < .0001). Recipients on mechanical ventilation were younger, had lower forced vital capacity, and had diagnoses other than emphysema. Recipients on extracorporeal membrane oxygenation were also younger, had higher body mass index, and had diagnoses other than cystic fibrosis/bronchiectasis. Once these variables, transplant year, and propensity for mechanical support were accounted for, survival remained worse after lung transplantation for patients on mechanical ventilation and extracorporeal membrane oxygenation.

CONCLUSION

Although survival after lung transplantation is markedly worse when preoperative mechanical support is necessary, it is not dismal. Thus, additional risk factors for mortality should be considered when selecting patients for lung transplantation to maximize survival. Reduced survival for this high-risk population raises the important issue of balancing maximal individual patient survival against benefit to the maximum number of patients.

Bridge to thoracic organ transplantation in patients with pulmonary arterial hypertension using a pumpless lung assist device

We describe a novel technique of pumpless extracorporeal life support in four patients with cardiogenic shock due to end-stage pulmonary hypertension (PH) including patients with veno-occlusive disease (PVOD) using a pumpless lung assist device (LAD). The device was connected via the pulmonary arterial main trunk and the left atrium, thereby creating a septostomy-like shunt with the unique addition of gas exchange abilities in parallel to the lung. Using this approach, all four patients were successfully bridged to bilateral lung transplantation and combined heart-lung transplantation, respectively. Although all patients presented in cardiogenic shock, hemodynamic unloading of the right ventricle using the low-resistance LAD stabilized the hemodynamic situation immediately so that no pump support was subsequently required.