Extracorporeal life support in lung and heart-lung transplantation for pulmonary hypertension in adults

Single Lung Transplant for Secondary Pulmonary Hypertension: The Right Option for the Right Patient

Introduction: The optimal treatment for Secondary Pulmonary Hypertension from End-Stage Lung Disease remains controversial. Double Lung Transplantation is widely regarded as the treatment of choice as it eliminates all diseased parenchyma and introduces a large volume of physiologically normal allograft. By comparison, the role of single lung transplantation for pulmonary hypertension (PAH) is less clear. The remaining diseased lung will limit clinical improvements and permit downstream sequelae; including residual cough, recurrent infection, and continued pulmonary hypertension. But not every patient can undergo DLT. Advanced age, frailty, co-morbid conditions, and limited availability of organs will all affect surgical candidacy and can offset the benefits of double lung procedures. Studies that compare SLT and DLT do not commonly explore the utility of single lung procedures even though multiple theoretical advantages exist; including reduced waiting times, less waitlist mortality, fewer surgical complications, and lower operative mortality. Worse, multiple forms of publication and selection bias may favor DLT in registry-based studies. In this review, we present the prevailing literature on single and double lung transplants in patients with secondary pulmonary hypertension and clarify the potential utility of these procedures. Materials and Methods: A PubMed search for English-language articles exploring single and double lung transplants in the setting of secondary pulmonary hypertension was conducted from 1990 to 2023. Key words included "single lung transplant", "double lung transplant", "pulmonary hypertension", "rejection", "complications", "extracorporeal membranous oxygenation", "death", and all appropriate Boolean operators. We prioritized research from retrospective studies that evaluated clinical outcomes from single centers. Conclusions: The question is not whether DLT is better at resolving lung disease; instead, we must ask if SLT is an acceptable form of therapy in a select group of high-risk patients. Further research should focus on how best to identify recipients that may benefit from each type of procedure, and the clinical utility of perioperative VA ECMO.

Mechanical Power Density Predicts Prolonged Ventilation Following Double Lung Transplantation

Prolonged mechanical ventilation (PMV) after lung transplantation poses several risks, including higher tracheostomy rates and increased in-hospital mortality. Mechanical power (MP) of artificial ventilation unifies the ventilatory variables that determine gas exchange and may be related to allograft function following transplant, affecting ventilator weaning. We retrospectively analyzed consecutive double lung transplant recipients at a national transplant center, ventilated through endotracheal tubes upon ICU admission, excluding those receiving extracorporeal support. MP and derived indexes assessed up to 36 h after transplant were correlated with invasive ventilation duration using Spearman's coefficient, and we conducted receiver operating characteristic (ROC) curve analysis to evaluate the accuracy in predicting PMV (>72 h), expressed as area under the ROC curve (AUROC). PMV occurred in 82 (35%) out of 237 cases. MP was significantly correlated with invasive ventilation duration (Spearman's ρ = 0.252 [95% CI 0.129-0.369], p < 0.01), with power density (MP normalized to lung-thorax compliance) demonstrating the strongest correlation (ρ = 0.452 [0.345-0.548], p < 0.01) and enhancing PMV prediction (AUROC 0.78 [95% CI 0.72-0.83], p < 0.01) compared to MP (AUROC 0.66 [0.60-0.72], p < 0.01). Mechanical power density may help identify patients at risk for PMV after double lung transplantation.

Circuit change during extracorporeal membrane oxygenation: single-center retrospective study of 48 changes

BACKGROUND

Bleeding and thrombosis induce major morbidity and mortality in patients under extracorporeal membrane oxygenator (ECMO). Circuit changes can be performed for oxygenation membrane thrombosis but are not recommended for bleeding under ECMO. The objective of this study was to evaluate the course of clinical, laboratory, and transfusion parameters before and after ECMO circuit changes warranted by bleeding or thrombosis.

METHODS

In this single-center, retrospective, cohort study, clinical parameters (bleeding syndrome, hemostatic procedures, oxygenation parameters, transfusion) and laboratory parameters (platelet count, hemoglobin, fibrinogen, PaO₂) were collected over the seven days surrounding the circuit change.

RESULTS

In the 274 patients on ECMO from January 2017 to August 2020, 48 circuit changes were performed in 44 patients, including 32 for bleeding and 16 for thrombosis. Mortality was similar in the patients with vs. without changes (21/44, 48% vs. 100/230, 43%) and in those with bleeding vs. thrombosis (12/28, 43% vs. 9/16, 56%, P = 0.39). In patients with bleeding, numbers of bleeding events, hemostatic procedures, and red blood cell transfusions were significantly higher before vs. after the change (P < 0.001); the platelet counts and fibrinogen levels decreased progressively before and increased significantly after the change. In patients with thrombosis, numbers of bleeding events and red blood cell transfusions did not change after membrane change. No significant differences were demonstrated between oxygenation parameters (ventilator FiO₂, ECMO FiO₂, and PaO₂) and ECMO flow before vs. after the change.

CONCLUSIONS

In patients with severe and persistent bleeding, changing the ECMO circuit decreased clinical bleeding and red blood cell transfusion needs and increased platelets and fibrinogen levels. Oxygenation parameters did not change significantly in the group with thrombosis.

Single Lung Transplant Remains a Viable Option for Patients With Severe Secondary Pulmonary Hypertension

BACKGROUND

Although double lung transplant is recommended in patients with severe secondary pulmonary hypertension (SPH), our institutional experiences suggest a role for single lung transplant in these patients. Here, we review our experience prioritizing single lung transplant in patients with SPH to minimize their surgical burden.

METHODS

We conducted a retrospective review of our lung transplant database to identify patients with SPH who underwent single lung transplant. Patients were stratified as either mild SPH (mean pulmonary artery pressure 25-40 mm Hg) or severe SPH (mean pulmonary artery pressure >40 mm Hg). Singe lung recipients without PH transplanted over the same time were also examined.

RESULTS

Between January 2017 and December 2019, 318 patients underwent single lung transplantation; 217 had mild SPH (68%), and 59 had severe SPH (18.5%). Forty-two patients without PH underwent single lung transplant. When the groups were compared, significantly higher pulmonary vascular resistance was noted in the severe SPH group, and obesity was noted in both the mild and severe SPH groups. Although the severe SPH group required more intraoperative cardiopulmonary support (37.3% versus 10.3% versus 4.7%, P < 0.05), there were no significant differences in most major postoperative parameters, including the duration of postoperative mechanical ventilation or the incidence of severe primary graft dysfunction. Survival 1 y posttransplant was not significantly different among the groups (93.2% versus 89.4% versus 92.9%, P = 0.58).

CONCLUSIONS

Our experience supports the option of single lung transplantation with appropriate intraoperative mechanical circulatory support in patients with SPH. This strategy is worth pursuing, especially with ongoing donor lung shortages.

Double Lung Transplantation Bridged With Direct Central Ambulatory Veno-Arterial Extracorporeal Membrane Oxygenation in a Pulmonary Hypertension Patient With Extreme Mediastinal Shift

Lung transplantation is increasingly being performed for end-stage lung disease in patients with bronchiectasis and pulmonary hypertension. Outcomes of bilateral lung transplantation (BLT) are better in patients with pulmonary hypertension, whereas single lung transplant remains a controversy in bronchiectasis with fear of infections from the residual diseased lung. However, in patients with adhesions and extreme structural changes due to severe disease, BLT may be considered technically challenging. We describe a case of successful management of a patient with bronchiectasis-induced lung disease causing extreme mediastinal shift with a BLT. The patient was successfully bridged to transplant with central veno-arterial extracorporeal membrane oxygenation (VA-ECMO) for acute decompensated pulmonary hypertension while awaiting transplantation.

Central versus peripheral cannulation of extracorporeal membrane oxygenation support during double lung transplant for pulmonary hypertension

OBJECTIVES

Extracorporeal membrane oxygenation (ECMO) has become the standard of cardiopulmonary support during a sequential double lung transplant for pulmonary hypertension. Whether central or peripheral cannulation is the best strategy for these patients remains unknown. Our goal was to determine which is the best strategy by comparing 2 populations of patients.

METHODS

We performed a single-centre retrospective study based on an institutional prospective lung transplant database.

RESULTS

Between January 2011 and November 2016, 103 patients underwent double lung transplant for pulmonary hypertension. We compared 54 patients who had central ECMO (cECMO group) to 49 patients who had peripheral ECMO (pECMO group). The pECMO group had significantly more bridged patients who received emergency transplants (31% vs 6%, P = 0.001). The incidence of Grade 3 primary graft dysfunction requiring ECMO (14% vs 11%, P = not significant) and of in-hospital mortality (11% vs 14%, P = not significant) was similar between the groups. Groin infections (16% vs 4%, P = 0.031), deep vein thrombosis (27% vs 11%, P = 0.044) and lower limb ischaemia (12% vs 2%, P = 0.031) occurred significantly more often in the pECMO group. The number of chest reopenings for bleeding or infection was similar between the groups. The 3-month, 1-year and 5-year survival rates did not differ between the groups (P = 0.94).

CONCLUSIONS

Central or peripheral ECMO produced similar results during double lung transplant for pulmonary hypertension in terms of in-hospital deaths and long-term survival rates. Central ECMO provided satisfactory results without major bleeding provided the patient was weaned from ECMO at the end of the procedure. Despite the rate of groin and lower limb complications, peripheral cannulation remained the preferred solution to bridge the patient to transplant or for postoperative support.

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%.

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.

Acute decompensated pulmonary hypertension

Acute right heart failure in chronic precapillary pulmonary hypertension is characterised by a rapidly progressive syndrome with systemic congestion resulting from impaired right ventricular filling and/or reduced right ventricular flow output. This clinical picture results from an imbalance between the afterload imposed on the right ventricle and its adaptation capacity. Acute decompensated pulmonary hypertension is associated with a very poor prognosis in the short term. Despite its major impact on survival, its optimal management remains very challenging for specialised centres, without specific recommendations. Identification of trigger factors, optimisation of fluid volume and pharmacological support to improve right ventricular function and perfusion pressure are the main therapeutic areas to consider in order to improve clinical condition. At the same time, specific management of pulmonary hypertension according to the aetiology is mandatory to reduce right ventricular afterload. Over the past decade, the development of extracorporeal life support in refractory right heart failure combined with urgent transplantation has probably contributed to a significant improvement in survival for selected patients. However, there remains a considerable need for further research in this field.

Acute decompensated PH is a life-threatening condition requiring specific management in a specialised centrehttp://ow.ly/non530fkhmA

Noteworthy Literature Published in 2016 for Thoracic Organ Transplantation Anesthesiologists

This article is first in the series to review the published literature on perioperative issues in patients undergoing thoracic solid organ transplantations. We present recent literature from 2016 on preoperative considerations, organ preservation, intraoperative anesthesia management, surgical techniques, postoperative complications, and the impact of perioperative management on short- and long-term outcomes that are pertinent to thoracic transplantation anesthesiologists.