Pro: lung transplantation should be routinely performed with cardiopulmonary bypass

A two-circuit strategy for intraoperative extracorporeal support during single lung transplantation in a patient bridged with venovenous extracorporeal membrane oxygenation

Venovenous extracorporeal membrane oxygenation is increasingly used as a bridging strategy in decompensating patients awaiting lung transplantation. Various approaches for continuing support intraoperatively have been previously described. A two-circuit strategy that uses the in situ venovenous extracorporeal membrane oxygenation circuit supplemented with peripheral cardiopulmonary bypass allows for diversion of native cardiac output away from the transplanted lung as well as seamless continuation of venovenous extracorporeal membrane oxygenation postoperatively.

Lung Transplantation for Pulmonary Artery Hypertension

This manuscript discusses the role of lung transplantation in patients with pulmonary hypertension. The indications and timing for referral to a transplant unit and timing for wait-listing for lung transplantation are discussed. The type of transplantation—isolated (single or double) lung transplantation and situations when combined heart and double lung transplantation is indicated—will be elaborated. Escalation of medical therapy with the need and timing for bridging therapies such as extracorporeal membrane oxygenation until an appropriate organ becomes available will be discussed. Challenges in the postoperative period, specific to lung transplantation for pulmonary artery hypertension, will be reviewed. The outcomes following lung transplantation will also be considered in greater detail.

Intraoperative Support for Primary Bilateral Lung Transplantation: A Propensity-Matched Analysis

BACKGROUND

Single-center studies support benefits of venoarterial extracorporeal membrane oxygenation (VA-ECMO) as a method of intraoperative support. Propensity-matched data from a large cohort, however, are currently lacking. Therefore, our goal was to compare outcomes of intraoperative VA-ECMO and cardiopulmonary bypass (CPB) during bilateral lung transplantation (LTx) with a propensity analysis.

METHODS

We performed a retrospective analysis of 795 consecutive primary adult LTx patients (June 1, 2011-December 26, 2020) using no intraoperative support (n = 210), VA-ECMO (n = 150), or CPB (n = 197). Exclusion criteria included LTx on venovenous-ECMO, single/redo LTx, ex vivo lung perfusion, and concomitant solid-organ transplantation or cardiac procedure. Propensity analysis was performed comparing patients who underwent intraoperative CPB or VA-ECMO.

RESULTS

The propensity CPB group required more blood products at 72 hours (P = .02) and longer intensive care unit length of stay (P < .001) and ventilator dependence days (P < .001). There were no differences in cerebrovascular accident (P = 1), reintubation (P = .4), dialysis (P = .068), in-hospital mortality (P = .33), and 1-year (P = .67) and 3-year (P = .32) survival. The CPB group had a higher incidence of grade 3 primary graft dysfunction at 72 hours (P < .001). Neither support strategy was a predictor of 1- and 3-year mortality in our multivariable model (VA-ECMO, P = .72 and P = .57; CPB, P = .45 and P = .91, respectively).

CONCLUSIONS

Intraoperative VA-ECMO during lung transplantation was associated with fewer postoperative blood transfusions, shorter length of mechanical ventilation, and lower incidence of a grade 3 primary graft dysfunction at 72 hours. Although there were some differences in the postoperative course between the VA-ECMO and CPB groups, support type was not associated with differences in survival.

Anesthetic Management During Lung Transplantation - What's New in 2021?

As outcomes of lung transplantation (LTx) are improving transplant centers are pushing boundaries. There has been a steady increase in the medical complexity of lung transplant candidates. Many transplant centers are listing older patients with comorbidities, and there has been a steady rise in the number of candidates supported with extracorporeal membrane oxygenation (ECMO) as a bridge to transplantation. There has been a growing appreciation of the importance intraoperative management of potentially modifiable risk factors has on postoperative outcomes. Evidence suggests that LTx even in high-risk patients requiring perioperative ECMO can offer excellent results. This article outlines the current state-of-the-art intraoperative management of LTx.

Volatile organic compound profiling to explore primary graft dysfunction after lung transplantation

Primary graft dysfunction (PGD) is a major determinant of morbidity and mortality following lung transplantation. Delineating basic mechanisms and molecular signatures of PGD remain a fundamental challenge. This pilot study examines if the pulmonary volatile organic compound (VOC) spectrum relate to PGD and postoperative outcomes. The VOC profiles of 58 bronchoalveolar lavage fluid (BALF) and blind bronchial aspirate samples from 35 transplant patients were extracted using solid-phase-microextraction and analyzed with comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometry. The support vector machine algorithm was used to identify VOCs that could differentiate patients with severe from lower grade PGD. Using 20 statistically significant VOCs from the sample headspace collected immediately after transplantation (< 6 h), severe PGD was differentiable from low PGD with an AUROC of 0.90 and an accuracy of 0.83 on test set samples. The model was somewhat effective for later time points with an AUROC of 0.80. Three major chemical classes in the model were dominated by alkylated hydrocarbons, linear hydrocarbons, and aldehydes in severe PGD samples. These VOCs may have important clinical and mechanistic implications, therefore large-scale study and potential translation to breath analysis is recommended.

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.

Extracorporeal membrane oxygenation in lung transplantation: Indications, techniques and results

The use of extracorporeal membrane oxygenation (ECMO) in the field of lung transplantation has rapidly expanded over the past 30 years. It has become an important tool in an increasing number of specialized centers as a bridge to transplantation and in the intra-operative and/or post-operative setting. ECMO is an extremely versatile tool in the field of lung transplantation as it can be used and adapted in different configurations with several potential cannulation sites according to the specific need of the recipient. For example, patients who need to be bridged to lung transplantation often have hypercapnic respiratory failure that may preferably benefit from veno-venous (VV) ECMO or peripheral veno-arterial (VA) ECMO in the case of hemodynamic instability. Moreover, in an intra-operative setting, VV ECMO can be maintained or switched to a VA ECMO. The routine use of intra-operative ECMO and its eventual prolongation in the post-operative period has been widely investigated in recent years by several important lung transplantation centers in order to assess the graft function and its potential protective role on primary graft dysfunction and on ischemia-reperfusion injury. This review will assess the current evidence on the role of ECMO in the different phases of lung transplantation, while analyzing different studies on pre, intra- and post-operative utilization of this extracorporeal support.

Cardiopulmonary bypass increases endothelial dysfunction after pulmonary ischaemia-reperfusion in an animal model

OBJECTIVES

Endothelial dysfunction during ischaemia-reperfusion (IR) is a major cause of primary graft dysfunction during lung transplantation. The routine use of cardiopulmonary bypass (CPB) during lung transplantation remains controversial. However, the contribution of CPB to pulmonary endothelial dysfunction remains unclear. The objective was to investigate the impact of CPB on endothelial dysfunction in a lung IR rat model.

METHODS

Rats were allocated to 4 groups: (i) Sham, (ii) IR, (iii) CPB and (iv) IR-CPB. The primary outcome was the study of pulmonary vascular reactivity by wire myograph. We also assessed glycocalyx degradation by enzyme-linked immunosorbent assay and electron microscopy and both systemic and pulmonary inflammation by enzyme-linked immunosorbent assay and immunohistochemistry. Rats were exposed to 45 min of CPB and IR. We used a CPB model allowing femoro-femoral support with left pulmonary hilum ischaemia for IR.

RESULTS

Pulmonary endothelium-dependent relaxation to acetylcholine was markedly reduced in the IR-CPB group (10.7 ± 9.1%) compared to the IR group (50.5 ± 5.2%, P < 0.001), the CPB group (54.1 ± 4.7%, P < 0.001) and the sham group (80.8 ± 6.7%, P < 0.001), suggesting that the association of pulmonary IR and CPB increases endothelial dysfunction. In IR-CPB, IR and CPB groups, vasorelaxation was completely abolished when inhibiting nitric oxide synthase, suggesting that this relaxation process was mainly mediated by nitric oxide. We observed higher syndecan-1 plasma levels in the IR-CPB group in comparison with the other groups, reflecting an increased degradation of glycocalyx. We also observed higher systemic inflammation in the IR-CPB group as shown by the increased plasma levels of IL-1β, IL-10.

CONCLUSIONS

CPB significantly increased the IR-mediated effects on pulmonary endothelial dysfunction. Therefore, the use of CPB during lung transplantation could be deleterious, by increasing endothelial dysfunction.

Perioperative circulatory support for lung transplantation

OBJECTIVE

Extracorporeal membrane oxygenation (ECMO) has recently replaced cardiopulmonary bypass (CPB) as the preferred option for providing circulatory support during lung transplantation. This review aimed to summarize the previous data and to address the relative use of ECMO and CPB during lung transplantation.

METHODS

The database was searched in PubMed (Medline) using the following keywords: lung transplantation, extracorporeal membrane oxygenation, and cardiopulmonary bypass, for all relevant reports which were written in English and were published between 2000 and 2020.

REVIEW

Several reports have revealed that intraoperative use of ECMO is associated with lower blood product transfusion requirements, shorter ventilator support, and shorter length of hospital stay. During recent years, preoperative ECMO has also been used with favorable outcomes as a bridge to lung transplantation in critically ill patients.

CONCLUSIONS

The use of ECMO during lung transplantation seems to reduce postoperative complications and improve short-term outcomes, relative to CPB. However, additional data should be collected through large multicenter randomized controlled trials. Furthermore, preoperative ECMO as a bridge to lung transplantation appears to provide favorable outcomes, although additional data are also needed from experienced transplant centers.

The Effect of Additional Stepwise Venous Inflow on Differential Hypoxia of Veno-Arterial Extracorporeal Membrane Oxygenation

Use of femoral-femoral veno-arterial (VA) extracorporeal membrane oxygenation (ECMO) for cardiopulmonary support during lung transplantation can be inadequate for efficient distribution of oxygenated blood into the coronary circulation. We hypothesized that creating a left-to-right shunt flow using veno-arterio-venous (VAV) ECMO would alleviate the differential hypoxia. Total 10 patients undergoing lung transplantation were enrolled in this study. An additional inflow cannula was inserted into the right internal jugular (RIJ) vein for VAV ECMO. During left one-lung ventilation using a 1.0 inspired oxygen fraction (FiO₂), the left-to-right shunt flow was incrementally increased from 0 to 500, 1,000, and 1,500 ml/min. The arterial oxygen partial pressure (PaO₂) and oxygen saturation (SaO₂) were measured at the proximal ascending aorta and right radial artery. The ascending aorta gas analysis revealed that six patients had a PaO₂/FiO₂ ratio less than 200 mm Hg at a 0 ml/min shunt flow. The PaO₂ (SaO₂) values were 48.5 ± 14.8 mm Hg (80.9 ± 11.6%) at the ascending aorta and 77.8 ± 69.7 mm Hg (83.3 ± 13.2%) at the right radial artery. As the left-to-right shunt flow rate increased over 1,000 ml/min, the PaO₂ and SaO₂ values for the ascending aorta and right radial artery significantly increased. In conclusion, femoral-femoral VA ECMO can produce suboptimal coronary oxygenation in patients unable to tolerate one-lung ventilation. A left-to-right shunt using VAV ECMO can alleviate the differential hypoxia.

Extracorporeal life support during and after bilateral sequential lung transplantation in patients with pulmonary artery hypertension

The use of extracorporeal membrane oxygenator instead of standard cardiopulmonary bypass during lung transplantation is debatable. Moreover, recently, the concept of prolonged postoperative extracorporeal membrane oxygenator (ECMO) support has been introduced in many transplant centers to prevent primary graft dysfunction (PGD) and improve early and long-term results. The objective of this study was to review the results of our extracorporeal life support strategy during and after bilateral sequential lung transplantation (BSLT) for pulmonary artery hypertension. We review retrospectively our experience in BSLT for pulmonary artery hypertension between January 2010 and August 2018. A total of 38 patients were identified. Nine patients were transplanted using cardiopulmonary bypass (CPB), in eight cases CPB was followed by a prolonged ECMO (pECMO) support, 14 patients were transplanted on central ECMO support, and seven patients were transplanted with central ECMO support followed by a pECMO assistance. The effects of different support strategies were evaluated, in particular in-hospital morbidity, mortality, incidence of PGD, and long-term follow-up. The use of CPB was associated with poor postoperative results and worse long-term survival compared with ECMO-supported patients. Predictive preoperative factors for the need of intraoperative CPB instead of ECMO were identified. The pECMO strategy had a favorable effect to mitigate postoperative morbidity and mortality, not only in intraoperative ECMO-supported patients, but even in CPB-supported cases. In our experience, ECMO may be considered as the first choice circulatory support for lung transplantation. Sometimes, in very complex cases, CBP is still necessary. The pECMO strategy is very effective to reduce incidence of PGD even in CPB-supported patients.

Lung transplantation via cardiopulmonary bypass: excellent survival outcomes from extended criteria donors

OBJECTIVES

The role of intraoperative cardiopulmonary bypass (CPB) in lung transplant (LTx) surgery is controversial. CPB enables slow pulmonary reperfusion and initial ventilation with low oxygen concentrations, both theoretically protective of transplanted lungs. In this study, we explored clinical outcomes following extended criteria donor LTx surgery implementing a thoroughly protective allograft reperfusion strategy using CPB.

METHODS

Thirty-nine consecutive adult patients who underwent bilateral LTx with elective CPB and protective allograft reperfusion were reviewed. Bilaterally implanted lungs were reperfused simultaneously, via slow CPB flow reduction and initial ventilation with 21% oxygen and nitric oxide, followed by a brief modified ultrafiltration. During weaning from CPB, mean pulmonary arterial pressure was strictly maintained at 10-15 mmHg by controlling CPB and pulmonary flow. The clinical outcomes in 23 patients who received lungs from extended criteria donors (ECD group) were elucidated and compared to 16 patients undergoing LTx from standard criteria donors (SCD group).

RESULTS

No life-threatening deterioration was observed to graft functionality during the first 72 h after LTx in the ECD group; however, only one patient required post-transplant extracorporeal membrane oxygenation. In three of 23 ECD LTx patients (12%), surgical revision for bleeding was required. Survival outcomes for the ECD group were favorable, with 100% survival at 6-months, 87.0% at 1-year, and 80.7% at 5-years. Outcomes in the ECD group were comparable to those in the SCD group.

CONCLUSIONS

Despite a certain extent of risk associated with full-dose heparinization, use of CPB does not undermine survival outcomes after ECD LTx surgery if protective allograft reperfusion is securely performed.

Blood Products Transfusion and Mid-Term Outcomes of Lung Transplanted Patients Under Extracorporeal Membrane Oxygenation Support

INTRODUCTION

Extracorporeal membrane oxygenation (ECMO) is considered a reliable technique in lung transplantation requiring cardiorespiratory support. However, the impact of this technology on blood product transfusion rate and outcomes compared to off-pump lung transplantation has been rarely investigated.

METHODS

Between January 2012 and June 2015, 52 elective adult lung transplants were performed at our institution. Of these, 15 recipients required intraoperative venoarterial extracorporeal support and 37 did not. We compared blood product consumption and other outcome variables between the 2 groups.

RESULTS

We found comparable in-hospital (86.7% vs 97.3%, P = .14) and 6-month (86.7% vs 91.9%, P = .56) survival between patients with and without extracorporeal support, respectively. Survival at 30 days was lower in the ECMO group (86.7% vs 100%, P = .02). Although patients who underwent ECMO received more intraoperative transfusions, postoperative transfusion rate was similar between the 2 groups. The ECMO group experienced longer mechanical ventilation (median 3 vs 2 days, P = .02) and intensive care unit stay (median 7 vs 5 days, P = .02), besides more cardiogenic shock and deep vein thrombosis. However, we observed no difference in other major and minor in-hospital complications and 6-month complications.

CONCLUSIONS

In our experience, despite the higher need for intraoperative transfusions, lung transplantation performed with ECMO support is comparable to the off-pump procedure as to short-term survival and outcomes.

Extracorporeal Circulation During Lung Transplantation Procedures: A Meta-Analysis

Extracorporeal circulation (ECC) is an invaluable tool in lung transplantation (lutx). More than the past years, an increasing number of centers changed their standard for intraoperative ECC from cardiopulmonary bypass (CPB) to extracorporeal membrane oxygenation (ECMO) - with differing results. This meta-analysis reviews the existing evidence. An online literature research on Medline, Embase, and PubMed has been performed. Two persons independently judged the papers using the ACROBAT-NRSI tool of the Cochrane collaboration. Meta-analyses and meta-regressions were used to determine whether veno-arterial ECMO (VA-ECMO) resulted in better outcomes compared with CPB. Six papers - all observational studies without randomization - were included in the analysis. All were considered to have serious bias caused by heparinization as co-intervention. Forest plots showed a beneficial trend of ECMO regarding blood transfusions (packed red blood cells (RBCs) with an average mean difference of -0.46 units [95% CI = -3.72, 2.80], fresh-frozen plasma with an average mean difference of -0.65 units [95% CI = -1.56, 0.25], platelets with an average mean difference of -1.72 units [95% CI = -3.67, 0.23]). Duration of ventilator support with an average mean difference of -2.86 days [95% CI = -11.43, 5.71] and intensive care unit (ICU) length of stay with an average mean difference of -4.79 days [95% CI = -8.17, -1.41] were shorter in ECMO patients. Extracorporeal membrane oxygenation treatment tended to be superior regarding 3 month mortality (odds ratio = 0.46, 95% CI = 0.21-1.02) and 1 year mortality (odds ratio = 0.65, 95% CI = 0.37-1.13). However, only the ICU length of stay reached statistical significance. Meta-regression analyses showed that heterogeneity across studies (sex, year of ECMO implementation, and underlying disease) influenced differences. These data indicate a benefit of the intraoperative use of ECMO as compared with CPB during lung transplant procedures regarding short-term outcome (ICU stay). There was no statistically significant effect regarding blood transfusion needs or long-term outcome. The superiority of ECMO in lutx patients remains to be determined in larger multi-center randomized trials.

History of lung transplantation

Lung transplantation nowadays is a well-accepted and routine treatment for well selected patients with terminal respiratory disease. However, it took several decades of experimental studies and clinical attempts to reach this success. In this paper, we describe the early experimental activity from the mid-forties until the early sixties. The first clinical attempt in humans was reported by Hardy and Webb in 1963 followed by others with short survival only except for one case by Derom et al. who lived for 10 months. Long-term successes were not reported until after the discovery of cyclosporine as a new immunosuppressive agent. Successful heart-lung transplantation (HLTx) for pulmonary vascular disease was performed by the Stanford group starting in 1981 while the Toronto group described good outcome after single-lung transplantation (SLTx) for pulmonary fibrosis in 1983 and after double-lung transplantation for emphysema in 1986. Further evolution in surgical techniques and in transplant type for the various forms of end-stage lung diseases are reviewed. The evolution in lung transplantation still continues nowadays with the use of pulmonary allografts coming from living-related donors, from donors after circulatory death, or after prior assessment and reconditioning during ex vivo lung perfusion (EVLP) in an attempt to overcome the critical shortage of suitable organs. Early outcome has significantly improved over the last three decades. Better treatment and prevention of chronic lung allograft dysfunction will hopefully result in further improvement of long-term survival after lung transplantation.

Risk Factor Analysis for Intraoperative Extracorporeal Membrane Oxygenation Weaning Failure After Lung Transplantation

BACKGROUND

Extracorporeal membrane oxygenation (ECMO) has been widely used for hemodynamic support during lung transplantation (LTx). We evaluated the risk factors associated with failure of weaning from ECMO in the operating room during LTx.

METHODS

We retrospectively reviewed 74 consecutive patients who had undergone LTx from March 2013 to February 2016. Patients who underwent single LTx, multiorgan transplantation, and LTx for pulmonary hypertension were excluded. All operations were performed under ECMO support. Clinical data of donor, recipient, and intraoperative parameters were reviewed.

RESULTS

Younger donors (40 ± 11 versus 45 ± 10 years, p = 0.047), donors with shorter mechanical ventilation (125 ± 74 versus 160 ± 80 minutes, p = 0.066) and donors with higher Pao₂ at 100% oxygen (455 ± 87 mm Hg versus 399 ± 88 mm Hg, p = 0.008) were significantly different in the ECMO weaning group than in the weaning failure group. Of the recipients, the number of patients who had preoperative ECMO support were significantly fewer in the successful weaning group than in the weaning failure group (11.9% versus 34.4%, p = 0.061). The operation time was significantly shorter in the weaning group than in the weaning failure group (392 ± 66 versus 435 ± 82 minutes, p = 0.014). In multivariate logistic regression analysis, the independent risk factors for ECMO weaning were donor age (odds ratio 1.101, 95% confidence interval: 1.030 to 1.177, p = 0.005), donor Pao₂ (odds ratio 0.992, 95% confidence interval: 0.984 to 0.999, p = 0.034), and operation time (odds ratio 1.010, 95% confidence interval: 1.000 to 1.019, p = 0.043).

CONCLUSIONS

Our results showed that younger donor age, high Pao₂, and shorter operation time were factors related to successful ECMO weaning in the operating room after LTx.

Extracorporeal Life Support in Lung Transplantation

Extracorporeal life support in lung transplantation has been associated with poor posttransplant outcomes. However, recent advances have resulted in more favorable posttransplant outcomes. The increased use of this technology must be weighed against the risks inherent in its use, especially when complications arising in extracorporeal membrane oxygenation (ECMO)-dependent patients result in loss of transplant candidacy, leaving them with no viable alternative for long-term support. Existing and emerging data support the judicious use of this technology in carefully selected patients at high-volume transplant and ECMO centers that prioritize minimization of sedation, avoidance of endotracheal intubation, and early mobilization.

Transition to routine use of venoarterial extracorporeal oxygenation during lung transplantation could improve early outcomes

BACKGROUND

The study objective was to compare the outcomes of intraoperative routine use of venoarterial (VA) extracorporeal membrane oxygenation (ECMO) versus selective use of cardiopulmonary bypass (CPB).

METHODS

Between January 2010 and February 2013, 41 lung transplantations (LTx) were performed, and CPB was used as a primary cardiopulmonary support modality by selective basis (group A). Between March 2013 and December 2014, 41 LTx were performed, and ECMO was used routinely (group B). The two groups were compared retrospectively.

RESULTS

The operative time was significantly longer in group A (group A, 458 min; group B, 420 min; P=0.041). Postoperatively, patients in group B had less fresh frozen plasma (FFP) transfusion (P=0.030). Complications were not different between the two groups. The 30- and 90-day survival rates were better in group B (30-day survival: group A, 75.6%; group B, 95.1%, P=0.012; 90-day survival: group A, 68.3%; group B, 87.8%, P=0.033). The 1-year survival showed better trends in group B, but it was not significant. Forced vital capacity (FVC) at 1, 3, and 6 months after LTx was better in group B than in group A (1 month: group A, 43.8%; group B, 52.9%, P=0.043; 3 months: group A, 45.5%; group B, 59.0%, P=0.005; 6 months: group A, 51.5%; group B, 65.2%, P=0.020). Forced expiratory volume in 1 second (FEV1) at 3 months after LTx was better in patients in group B than that in patient in group A (group A, 53.3%; group B, 67.5%, P=0.017).

CONCLUSIONS

Routine use of ECMO during LTx could improve early outcome and postoperative lung function without increased extracorporeal-related complication such as vascular and neurologic complications.

A simple technique can reduce cardiopulmonary bypass use during lung transplantation

Cardiopulmonary bypass causes an inflammatory response and consumption of coagulation factors, increasing the risk of bleeding and neurological and renal complications. Its use during lung transplantation may be due to pulmonary hypertension or associated cardiac defects or just for better exposure of the pulmonary hilum. We describe a simple technique, or open pericardium retraction, to improve hilar exposure by lifting the heart by upward retraction of the pericardial sac. This technique permits lung transplantation without cardiopulmonary bypass when bypass use is recommended only for better exposure.

New horizons of non-emergent use of extracorporeal membranous oxygenator support

The expansion of the extra corporeal membrane oxygenation (ECMO) use and its indication is strikingly increased in the past few years. ECMO use expanded to lung transplantation, difficult general thoracic resections, transcatheter aortic valve replacement (TAVR) and LVAD implantation. Here we will discuss the indications and the outcomes of non-emergent use of ECMO.

Outcomes of minimally invasive lung transplantation in a single centre: the routine approach for the future or do we still need clamshell incision?

OBJECTIVES

Minimally invasive lung transplantation (MILT) via bilateral anterior thoracotomies has emerged as a novel surgical strategy with potential patient benefits when compared with transverse thoracosternotomy (clamshell incision, CS). The aim of this study is to compare MILT with CS by focusing on operative characteristics, postoperative organ function and support and mid-term clinical outcomes at Harefield Hospital.

METHODS

It was a retrospective observational study evaluating all bilateral sequential lung transplants between April 2010 and November 2013.

RESULTS

CS was performed in 124 patients and MILT in 70 patients. Skin-to-skin surgical time was less in the MILT group [285 (265, 339) min] compared with CS [380 (306, 565) min] and MILT-cardiopulmonary bypass [426 (360, 478) min]. Ischaemic time was significantly longer (502 ± 116 vs 395 ± 145 min) in the MILT group compared with CS (P < 0.01). Early postoperative physiological variables were similar between groups. Patients in the MILT group required less blood [2 (0, 4) vs 3 (1, 5) units, P = 0.16] and platelet transfusion [0 (0, 1) vs 1 (0, 2) units, P < 0.01]. The median duration of mechanical ventilation was shorter (26 vs 44 h, P < 0.01) and intensive therapy unit stay was 2 days shorter (5 vs 7) in the MILT group. While overall survival was similar, fraction of expired volume in 1 s (FEV1) and forced vital capacity (FVC) were consistently higher in the MILT group compared with CS during mid-term follow-up after transplantation. Specifically, FEV1 and FVC were, respectively, 86 ± 21 and 88 ± 18% predicted in the MILT group compared with 74 ± 21 and 74 ± 19% predicted in the CS group (P < 0.01) at the 6-month follow-up.

CONCLUSIONS

MILT was successfully introduced at our centre as a novel operative strategy. Despite longer ischaemic times and a more complex operation and management, MILT appears to offer early postoperative and mid-term clinical benefits compared with our traditional approach of clamshell operations. These observations warrant larger definite studies to further evaluate the impact of MILT on physiological, clinical and patient-reported outcomes.

Mechanical circulatory support in lung transplantation: Cardiopulmonary bypass, extracorporeal life support, and ex-vivo lung perfusion

Lung transplant is the standard of care for patients with end-stage lung disease refractory to medical management. There is currently a critical organ shortage for lung transplantation with only 17% of offered organs being transplanted. Of those patients receiving a lung transplant, up to 25% will develop primary graft dysfunction, which is associated with an 8-fold increase in 30-d mortality. There are numerous mechanical lung assistance modalities that may be employed to help combat these challenges. We will discuss the use of mechanical lung assistance during lung transplantation, as a bridge to transplant, as a treatment for primary graft dysfunction, and finally as a means to remodel and evaluate organs deemed unsuitable for transplant, thus increasing the donor pool, improving survival to transplant, and improving overall patient survival.

Outcomes of intraoperative extracorporeal membrane oxygenation versus cardiopulmonary bypass for lung transplantation

OBJECTIVE

The study objective was to compare the outcomes of intraoperative extracorporeal membrane oxygenation versus cardiopulmonary bypass support in lung transplantation.

METHODS

We performed a retrospective cohort study from a prospective database of adult lung transplantations performed at the University of Toronto from 2007 to 2013. Among 673 lung transplantations performed in the study period, 267 (39.7%) required cardiopulmonary support. There were 39 cases of extracorporeal membrane oxygenation (2012-2013) and 228 cases of cardiopulmonary bypass (2007-2013). Patients who were bridged with extracorporeal life support, underwent a concomitant cardiac procedure, received a combined liver or heart transplant, were colonized with Burkholderia cenocepacia, or required emergency cannulation for cardiopulmonary support were excluded. Finally, 33 extracorporeal membrane oxygenation cases were matched with 66 cases of cardiopulmonary bypass according to age (±10 years), lung transplantation indication, and procedure type (bilateral vs single lung transplantation).

RESULTS

Recipient factors such as body mass index and gender were not different between extracorporeal membrane oxygenation and cardiopulmonary bypass groups. Furthermore, donor variables were similar, including age, body mass index, last PaO2/FiO2 ratio, smoking history, positive airway cultures, and donor type (brain death and donation after cardiac death). Early outcomes, such as mechanical ventilation requirement, length of intensive care unit stay, and length of hospital stay, significantly favored extracorporeal membrane oxygenation (median 3 vs 7.5 days, P = .005; 5 vs 9.5 days, P = .026; 19 vs 27 days, P = .029, respectively). Perioperative blood product transfusion requirement was lower in the extracorporeal membrane oxygenation group. The 90-day mortality for the extracorporeal membrane oxygenation group was 6% versus 15% for cardiopulmonary bypass (P = .32).

CONCLUSIONS

Extracorporeal membrane oxygenation may be considered as the first choice of intraoperative cardiorespiratory support for lung transplantation.

Comparison of single lung transplant with and without the use of cardiopulmonary bypass

OBJECTIVES

Many centres avoid using cardiopulmonary bypass (CPB) for lung transplant due to concerns over aggravated lung reperfusion injury and excessive blood loss. We reviewed our 23-years' experience of single lung transplantation.

METHODS

A retrospective review of single lung transplants at our institution (1987-2010), examining differences in allograft function and postoperative complications between CPB and non-bypass (non-CPB) cases.

RESULTS

Two hundred and fifty-nine single lung transplants were undertaken. Fifty-three (20.5%) with CPB. There was no difference demographically between the two groups. No difference existed in preoperative PO(2)/FiO(2). At 1 and 24 h, the postoperative PO(2)/FiO(2) ratio was no different (mean 2.95 and 3.24 in non-CPB cases; 3.53 and 3.75 in CPB patients, P = 0.18 and P = 0.34, respectively). Extubation time was not influenced by the use of CPB. Postoperative blood loss was greater in the CPB group. The usage of fresh frozen plasma and platelets was similar (P = 0.64 and 0.41, respectively). More blood was transfused during postoperative care of CPB patients (P = 0.02).

CONCLUSIONS

Fears of poor postoperative lung function after CPB appear unfounded. We could detect no difference in function or extubation time. Although the use of CPB increases postoperative bleeding and the need for transfusion, it may be used safely to facilitate lung transplantation.

[Place of traditional CBP in bipulmonary transplantation]

Initially double-lung transplantation (DLT) was performed with airway anastomosis at the tracheal bifurcation requiring a cardiopulmonary bypass (CBP). Complications related to ischemia of the bronchi and trachea around the carina prompted adoption of sequential single lung implantations as the method of choice for DLT. In different studies, CPB was associated with an increase in postoperative morbidity but this was probably due to the selection of more severe patients. Moreover, important progress in the technology of CPB has occurred. Therefore, the systematic use of CPB during sequential lung transplantation might have some interest by limiting the occurrence of ventilation and perfusion injuries. This article discusses the potential beneficial effects of CPB during double-lung transplantation.

Extracorporeal circulatory support for lung transplantation: institutional experience

Lung transplantation (LT) represents the only available therapy for selected patients affected by end-stage pulmonary disease. Cardiopulmonary bypass (CPBP) is used, when required, during single and sequential double lung transplantation; however, it increases the risk of bleeding, early graft dysfunction, failure, and other potential side effects. We report our experience with 145 patients who underwent lung transplantations, among whom 34 required intraoperative CPBP. The indications for LT among these 34 patients were cystic fibrosis (n = 22), chronic obstructive pulmonary disease (n = 3), bronchiectasis (n = 2), primary pulmonary hypertension (n = 1), fibrosis (n = 2), pulmonary microlithiasis (n = 1), and retransplantation for obliterative bronchilitis (n = 3). CPBP was planned in 12 cases (group I) and unplanned in 22 (group II). The main reason for planning CPBP was primary and secondary pulmonary hypertension (mean pulmonary artery pressure >or=25 mm Hg). Acute right ventricular failure, hemodynamic instability, arterial desaturation, and increased pulmonary artery pressure were mandatory for unplanned CPBP. Among the 34 CPBP patients, the 30-day mortality rate was 35% (12/34) including 9 (70%) in group II (unplanned CPBP). The leading cause of death was multiorgan failure. The 1-year survival rates were 67% and 36%, and the 3-year survival rates were 47% and 18% for groups I and II, respectively. In conclusion, even if it represents a useful tool in the management of critical events, the use of unscheduled CPBP during LT procedures is associated with an increased postoperative morbidity and mortality.

Modified low-flow ultrafiltration ameliorates hemodynamics and early graft function and reduces blood loss in living-donor lobar lung transplantation

BACKGROUND

This study analyzed the clinical application of modified low-flow ultrafiltration (MUF) to minimize cardiopulmonary bypass (CPB)-related adverse effects in patients undergoing living-donor lobar lung transplantation (LDLLT).

METHOD

The study enrolled 33 consecutive patients who underwent LDLLT from 1999 to 2004: 8 patients underwent conventional CPB without MUF (control group), and 15 underwent arteriovenous MUF (MUF-treated group). Hemodynamics, graft function, blood loss and blood transfusion requirements, and clinical outcomes were analyzed.

RESULTS

There was a significant increase in systolic blood pressure and a decrease in pulmonary to systemic pressure ratio in the MUF-treated group (p < 0.05). No hemodynamic changes occurred in the control group. MUF resulted in significant improvements in arterial oxygen tension/fraction of inspired oxygen ratio (PaO(2)/FiO(2;) 411 +/- 107 vs 272 +/- 107 mm Hg, p < 0.05) and the alveolar-arterial oxygen difference (a-aDO(2); 158 +/- 84 vs 315 +/- 127 mm Hg, p < 0.05) at 15 minutes after CPB. There were no differences in PaO(2)/FiO(2) and A-aDO(2) between the groups beyond 6 hours post-operatively. Post-operative blood loss and blood transfusion requirements were lower in the MUF-treated group than in the control group (p < 0.05). There were no differences in survival, duration of ventilation, intensive care unit stay, and hospital stay between the groups.

CONCLUSIONS

The low-flow MUF brought improved hemodynamics and gas exchange capacity of transplanted grafts and lowered post-operative blood loss and blood transfusion requirement. This strategy may minimize CPB-related adverse effects in patients undergoing LDLLT.

Influence of normothermic cardiopulmonary bypass on body oxygen metabolism during lung transplantation

Studies have demonstrated that cardiopulmonary bypass (CPB) adversely affects pulmonary circulation, which is involved in metabolism in the lung, and that pulmonary circulation after CPB can restore the prostaglandin E2 (PGE2) level mainly standing for levels of key vasostimulators augmented during CPB, which may influence systemic tissue perfusion and body oxygen metabolism. However, in lung transplantation (Lx), pulmonary circulation is restored to the graft, which might induce another CPB reaction. We prospectively examined the influence of CPB on body oxygen metabolism in Lx. Left Lx was successfully performed on 10 dogs (group-on: with normothermic CPB without cardiac arrest, group-off: without CPB; n = 5 vs. 5). At 30 minutes after graft perfusion, the right pulmonary artery and bronchus were clamped. Body weight, donor-to-recipient body weight ratio, and clinical parameters were comparable between the two groups, except for the hematocrit level during CPB. At 90 minutes after graft perfusion, mixed venous oxygen saturation (SvO2) was lower (p < 0.01) and O2 extraction rate (p < 0.01), PGE2 (p = 0.025), and arterial blood ketone body ratio (KBR) (p < 0.01) were higher in group-on than in group-off, whereas these parameters were comparable before graft perfusion between the two groups. O2 consumption and acetic acid were higher in group-on than in group-off, whereas O2 delivery and 3-hydroxy propioic acid were comparable between the groups. In conclusion, Lx during CPB may induce a new inflammatory reaction and influence body oxygen metabolism, contrary to the restoration of pulmonary circulation after CPB.

Ultrafiltration attenuates cardiopulmonary bypass-induced acute lung injury in a canine model of single-lung transplantation

OBJECTIVE

The purpose of this study was to investigate the effects of cardiopulmonary bypass and ultrafiltration on graft function in a canine single-lung transplantation model.

METHODS

Fifteen left single-lung transplantations were done in weight-mismatched canine pairs. The animals were divided into 3 groups: group 1, in which transplantation was done without cardiopulmonary bypass; group 2, in which transplantation was done with cardiopulmonary bypass and in which the cardiopulmonary bypass flow was decreased slowly with controlled pulmonary artery pressure; and group 3, in which transplantation was done with cardiopulmonary bypass and ultrafiltration. Hemodynamic parameters and lung function were monitored for 6 hours after reperfusion. The grafts were harvested for histologic studies, myeloperoxidase assay, and real-time quantitative reverse transcription-polymerase chain reaction of mRNA encoding interleukin 6.

RESULTS

The hemodynamic parameters were similar among the 3 groups. In group 1 PaO2 and alveolar to arterial gradient for O2 levels were excellent throughout the 6-hour observation period, but in group 2 they progressively deteriorated. However, ultrafiltration significantly (P = .02) improved the PaO2 level in group 3. On histology, interstitial edema and polynuclear cell infiltration were most marked in group 2 and significantly worse than in groups 1 and 3. Myeloperoxidase assay and real-time quantitative reverse transcription-polymerase chain reaction showed increased myeloperoxidase activity and interleukin 6 gene expression in group 2 grafts compared with group 1 grafts. Myeloperoxidase activity and interleukin 6 gene expression were suppressed with ultrafiltration.

CONCLUSIONS

Cardiopulmonary bypass had negative effects on the graft, but ultrafiltration attenuated acute lung dysfunction by reducing the inflammatory response.

Use of cardiopulmonary bypass for lung transplantation: a 10-year experience

OBJECTIVE

The use of cardiopulmonary bypass (CPB) for lung transplantation (LTx) has been reported previously. This study reports the authors' experience of planned and unplanned use of cardiopulmonary bypass for LTx.

DESIGN

Case series.

SETTING

A university teaching hospital.

PARTICIPANTS

Patients undergoing LTx.

INTERVENTIONS

A retrospective analysis of the charts of all patients having undergone LTx over the last 10 years.

MEASUREMENTS AND MAIN RESULTS

Among 140 LTx, 23 (16%) were performed with the use of CPB. CPB was planned in 11 cases and unplanned in the 12 other cases. The use of CPB is associated with a longer period of postoperative mechanical ventilation, more pulmonary edema, more blood transfusion requirement, and an increase in postoperative mortality at 48 hours and 1 month. Surgical difficulties related to the dissection of the native left lung and acute right ventricular failure are the main reasons for unscheduled use of CPB.

CONCLUSION

Scheduled and unscheduled CPB for LTx are associated with an increased mortality at 1 month and 1 year.

Inhaled Nitric Oxide Does Not Prevent Pulmonary Edema After Lung Transplantation Measured By Lung Water Content

STUDY OBJECTIVE

In order to assess the effects of inhaled nitric oxide (iNO) in preventing early-onset lung edema from occurring after lung transplantation, we measured extravascular lung water (EVLW) in a group of lung transplant recipients who were at high risk for developing ischemia-reperfusion-induced lung injury.

DESIGN

Prospective, randomized study.

SETTINGS

Surgical ICU in a teaching hospital.

PATIENTS

Thirty double-lung transplant recipients.

INTERVENTIONS

Patients were randomized to receive or not receive 20 ppm iNO at the time of reperfusion (ie, before any occurrence of lung edema). In the NO group, iNO was then administered for a 12-h period. A double-dilution technique was used for the serial assessment of EVLW, intrathoracic blood volume, and cardiac index. Standard hemodynamic and pulmonary parameters were also recorded during the first 3 postoperative days.

MEASUREMENTS AND RESULTS

Patients who received iNO did not have a different lung water content compared to control subjects (p = 0.61 [by analysis of variance (ANOVA)]). Blood oxygenation (ie, Pao(2)/fraction of inspired oxygen [Fio(2)] ratio) did not differ between the two groups (p = 0.61 [by ANOVA]). In both groups, EVLW and Pao(2)/Fio(2) ratio dropped significantly over time, regardless of the use of iNO (p < 0.01 [by ANOVA]).

CONCLUSIONS

In the population studied, prophylactic iNO that was administered at 20 ppm had no effect on pulmonary edema formation and resolution following lung transplantation.

Outcome of lung transplantation for patients requiring concomitant cardiac surgery

BACKGROUND

The clinical results of lung transplantation and concomitant cardiac surgery are unclear. The effect of cardiopulmonary bypass on the pulmonary allograft is controversial, and the effect of cardiac arrest and cardiac surgery in this setting is unknown. Our aim was to review the operative results and long-term survival in this group of patients.

METHODS

A retrospective review of all lung transplantations between 1988 and 2003 was performed. Patients who had concomitant cardiac surgery during lung transplantation were compared with those who underwent lung transplantation alone. The variables analyzed included allograft ischemic times, use of cardiopulmonary bypass, early graft dysfunction, postoperative morbidity, survival, length of mechanical ventilation, length of stay in the intensive care unit, and overall hospital stay.

RESULTS

During this period, 35 of 700 lung transplant recipients (15 single and 20 bilateral transplantations) underwent concomitant cardiac surgery. The cardiac procedures were for patent foramen ovale (n = 18), atrial septal defect (n = 9), ventricular septal defect (n = 2), coronary bypass (n = 4), and "other" (n = 2). Allograft ischemic time, use of extracorporeal membrane oxygenation, length of hospital stay, operative mortality, and survival were not significantly different between the 2 groups. Ventilator time and intensive care unit stay were longer in the cardiac surgery group.

CONCLUSIONS

Cardiac surgery at the time of lung transplantation can be performed with acceptable morbidity and mortality. The immediate and long-term survival in these patients is similar to that of other lung transplant recipients. Lung transplantation should continue to be offered to patients with normal ventricular function who require concomitant limited cardiac surgery.

Anesthetic Considerations for Lung Volume Reduction Surgery and Lung Transplantation

Anesthetic considerations for lung transplantation and LVRS have been reviewed, with an emphasis on critical intraoperative junctures and decision points. Cognizance of these issues promotes coordinated and optimal care and provides the potential to improve outcome in this particularly high-risk population.

Basal and nitroglycerin-induced exhaled nitric oxide before and after cardiac surgery with cardiopulmonary bypass

BACKGROUND

Exhaled nitric oxide (NO) may reflect NO production and consumption but the pulmonary origin of NO in exhaled gas is not clear. There are also conflicting data on exhaled NO after cardiopulmonary bypass (CPB). Because intravenous nitrovasodilators increase exhaled NO by conversion to NO in the lung, we measured basal and nitroglycerin (GTN)-induced exhaled NO in patients having low-risk coronary artery bypass graft (CABG) operations using routine CPB. We reasoned that GTN-induced exhaled NO would be a primarily vascular mechanism, which would contrast with the airway epithelial origin of basal exhaled NO, and that they might be differentially influenced by CPB.

METHODS

Breath-to-breath concentrations of gas phase NO were measured in 12 CABG patients before and 1, 3 and 6 h after CPB. After the baseline measurements, three increasing doses of 1, 2 and 3 micro g kg(-1) intravenous GTN were given by a central venous catheter and exhaled NO and haemodynamic responses were recorded.

RESULTS

Intravenous administration of 1, 2 and 3 micro g kg(-1) doses of GTN produced a dose-dependent increase in exhaled NO and a reduction in systemic blood pressure. Baseline exhaled NO remained unchanged. Exhaled NO but not blood pressure responses were reduced 1 and 3 h after CPB.

CONCLUSIONS

The capacity of the lungs to increase exhaled NO in response to intravenous GTN is reduced after CPB, suggesting microvascular injury and/or atelectasis after routine open-heart surgery.

Ischemia-reperfusion-induced lung injury

Ischemia-reperfusion-induced lung injury is characterized by nonspecific alveolar damage, lung edema, and hypoxemia occurring within 72 hours after lung transplantation. The most severe form may lead to primary graft failure and remains a significant cause of morbidity and mortality after lung transplantation. Over the past decade, better understanding of the mechanisms of ischemia-reperfusion injury, improvements in the technique of lung preservation, and the development of a new preservation solution specifically for the lung have been associated with a reduction in the incidence of primary graft failure from approximately 30 to 15% or less. Several strategies have also been introduced into clinical practice for the prevention and treatment of ischemia-reperfusion-induced lung injury with various degrees of success. However, only three randomized, double-blinded, placebo-controlled trials on ischemia-reperfusion-induced lung injury have been reported in the literature. In the future, the development of new agents and their application in prospective clinical trials are to be expected to prevent the occurrence of this potentially devastating complication and to further improve the success of lung transplantation.

Survival benefit of cardiopulmonary bypass support in bilateral lung transplantation for emphysema patients

BACKGROUND

This study is designed to examine a possible association of cardiopulmonary bypass (CPB) support and outcome of lung transplantation in a well-balanced group of emphysema patients.

METHODS

We performed a retrospective analysis of 62 consecutive primary bilateral lung transplantations for emphysema. Risk factors for their possible association with patient survival were analyzed by multivariate logistic regression.

RESULTS

The use of CPB support was associated with improved survival (odds ratio=0.25; P=0.038). The actuarial survival at 1 year was 97% for patients treated with CPB and 77% for patients treated without CPB support. In 28 patients (45%), 2 human leukocyte antigen (HLA)-DR mismatches between donor and recipient occurred, whereas 34 patients had 0 or 1 HLA-DR mismatches. The use of CPB support in the group with two HLA-DR mismatches was associated with improved survival (odds ratio=0.06; P=0.020). This association was not present in the group with 0 or 1 HLA-DR mismatches.

CONCLUSIONS

These results demonstrate a significant survival benefit of CPB support during bilateral lung transplantation in emphysema patients. The difference in survival benefit of CPB support between the patients with 0 or 1 HLA-DR mismatches and the patients with 2 HLA-DR mismatches indicates that the immunosuppressive effect of CPB support might be responsible for this survival benefit. The underlying immunological mechanism might be important in the future treatment of organ transplantation.