Postoperative vasoplegia in lung transplantation: incidence and relation to outcome in a single-centre retrospective study.

BACKGROUND: The incidence and clinical importance of vasoplegia after lung transplantation remains poorly studied. We describe the incidence of vasoplegia and its association with complications after lung transplantation. METHODS: Perioperative data of 279 lung transplant recipients operated on from 2015 to 2020 in a UK hospital were analysed retrospectively. RESULTS: Vasoplegia occurred in 41.6% of patients after lung transplantation (mild, 31.0%; moderate, 55.2%; severe, 13.8%). Compared with non-vasoplegic patients, vasoplegic patients had a higher incidence of any acute kidney injury, defined by Kidney Disease Improving Global Outcomes (KDIGO) criteria (78.5% vs 65%, P=0.015), renal replacement therapy (47.4% vs 24.5%, P<0.001), and delayed chest closure (18.4% vs 9.2%, P=0.025); were ventilated longer (70 [32-368] vs 34 [19-105] h, P<0.001); and stayed longer in the ICU (12.9 [5-30] vs 6.8 [3-20] days, P<0.001). Mortality at 30 days and 1 yr was higher in patients with vasoplegia (11.2% vs 5.5% and 20.7% vs 11.7%, P=0.039, respectively). Severe vasoplegia represented a predictor of longer-term mortality (hazard ratio=1.65, P=0.008). Underlying infectious disease, increased BMI, higher preoperative pulmonary artery systolic pressure and bilirubin levels, lower glomerular filtration rate, and increased fresh frozen plasma transfusion were predictors of vasoplegia severity. Neutrophilia, leucocytosis, and increased C-reactive protein were associated with vasoplegia, but release of the neutrophil activation markers myeloperoxidase and heparin-binding protein was similar between groups. CONCLUSIONS: Influenced by preoperative status as well as procedural factors and inflammatory response, vasoplegia is a common and critical condition after lung transplantation with worse short-term outcomes and long-term survival.

ATP redirects cytokine trafficking and promotes novel membrane TNF signaling via microvesicles.

Cellular stress or injury induces release of endogenous danger signals such as ATP, which plays a central role in activating immune cells. ATP is essential for the release of nonclassically secreted cytokines such as IL-1ß but, paradoxically, has been reported to inhibit the release of classically secreted cytokines such as TNF. Here, we reveal that ATP does switch off soluble TNF (17 kDa) release from LPS-treated macrophages, but rather than inhibiting the entire TNF secretion, ATP packages membrane TNF (26 kDa) within microvesicles (MVs). Secretion of membrane TNF within MVs bypasses the conventional endoplasmic reticulum- and Golgi transport-dependent pathway and is mediated by acid sphingomyelinase. These membrane TNF-carrying MVs are biologically more potent than soluble TNF in vivo, producing significant lung inflammation in mice. Thus, ATP critically alters TNF trafficking and secretion from macrophages, inducing novel unconventional membrane TNF signaling via MVs without direct cell-to-cell contact. These data have crucial implications for this key cytokine, particularly when therapeutically targeting TNF in acute inflammatory diseases.-Soni, S., O'Dea, K. P., Tan, Y. Y., Cho, K., Abe, E., Romano, R., Cui, J., Ma, D., Sarathchandra, P., Wilson, M. R., Takata, M. ATP redirects cytokine trafficking and promotes novel membrane TNF signaling via microvesicles.

Intravascular donor monocytes play a central role in lung transplant ischaemia-reperfusion injury.

RATIONALE: Primary graft dysfunction in lung transplant recipients derives from the initial, largely leukocyte-dependent, ischaemia-reperfusion injury. Intravascular lung-marginated monocytes have been shown to play key roles in experimental acute lung injury, but their contribution to lung ischaemia-reperfusion injury post transplantation is unknown. OBJECTIVE: To define the role of donor intravascular monocytes in lung transplant-related acute lung injury and primary graft dysfunction. METHODS: Isolated perfused C57BL/6 murine lungs were subjected to warm ischaemia (2 hours) and reperfusion (2 hours) under normoxic conditions. Monocyte retention, activation phenotype and the effects of their depletion by intravenous clodronate-liposome treatment on lung inflammation and injury were determined. In human donor lung transplant samples, the presence and activation phenotype of monocytic cells (low side scatter, 27E10+, CD14+, HLA-DR+, CCR2+) were evaluated by flow cytometry and compared with post-implantation lung function. RESULTS: In mouse lungs following ischaemia-reperfusion, substantial numbers of lung-marginated monocytes remained within the pulmonary microvasculature, with reduced L-selectin and increased CD86 expression indicating their activation. Monocyte depletion resulted in reductions in lung wet:dry ratios, bronchoalveolar lavage fluid protein, and perfusate levels of RAGE, MIP-2 and KC, while monocyte repletion resulted in a partial restoration of the injury. In human lungs, correlations were observed between pre-implantation donor monocyte numbers/their CD86 and TREM-1 expression and post-implantation lung dysfunction at 48 and 72 hours. CONCLUSIONS: These results indicate that lung-marginated intravascular monocytes are retained as a 'passenger' leukocyte population during lung transplantation, and play a key role in the development of transplant-associated ischaemia-reperfusion injury.

The role of cardiopulmonary bypass in lung transplantation.

BACKGROUND: The risk-benefit for utilizing cardio-pulmonary bypass (CPB) in lung transplantation (LTx) remains debatable. This study compares outcomes after LTx utilizing different CPB strategies - elective CPB vs. off-pump vs. off-pump with unplanned conversion to CPB. METHODS: A total of 302 LTx performed over seven yr were divided into three groups: "off-pump" group (n = 86), "elective on-pump" group (n = 162), and "conversion" group (n = 54). The preoperative donor and recipient demographics and baseline characteristics and the postoperative outcomes were analyzed; 1:1 propensity score matching was used to identify patients operated upon using elective CPB who had risk profiles similar to those operated upon off-pump (propensity-matching 1) as well as those emergently converted from off-pump to CPB (propensity-matching 2). RESULTS: Preoperative group demographic characteristics were comparable; however, the "off-pump" patient group was significantly older. The "conversion" group had a significantly greater number of patients with primary pulmonary hypertension, pulmonary fibrosis, preoperative mechanical ventilation, and preoperative extracorporeal life support (ECLS). Postoperatively, patients from the "conversion" group had significantly poorer PaO2 /FiO2 ratios upon arrival in intensive care unit (ICU) and at 24, 48, and 72 h postoperatively, and they required more prolonged ventilation, longer ICU admission, and they experienced an increased need for ECLS than the other groups. Overall, cumulative survival at one, two, and three yr was significantly worse in patients from the "conversion" group compared to the "off-pump" and "elective on-pump" groups - 61.9% vs. 94.4% vs. 86.9%, 54.4% vs. 90.6% vs. 79.5% and 39.8% vs. 78.1% vs. 74.3%, respectively (p < 0.001). The "off-pump" group had significantly better PaO2 /FiO2 ratios, and a significantly shorter duration of ventilation, ICU stay, and hospital length of stay when compared to the propensity-matched "elective on-pump" group. There were no statistically significant differences in postoperative outcomes and overall survival between the "converted" group and the propensity-matched "elective on-pump" group. CONCLUSIONS: Despite segregation of unplanned CPB conversion cases from elective on-pump cases, patients with comparable preoperative demographic/risk profiles demonstrated better early postoperative outcomes and, possibly, an improved early survival with an off-pump strategy. A considerable proportion of high-risk patients require intraoperative conversion from off-pump to CPB, and this seems associated with suboptimal outcomes; however, there is no significant benefit to employing an elective on-pump strategy over emergent conversion in the high-risk group.

Inhaled nitric oxide in cardiac surgery: Evidence or tradition?

Inhaled nitric oxide (iNO) therapy as a selective pulmonary vasodilator in cardiac surgery has been one of the most significant pharmacological advances in managing pulmonary hemodynamics and life threatening right ventricular dysfunction and failure. However, this remarkable story has experienced a roller-coaster ride with high hopes and nearly universal demonstration of physiological benefits but disappointing translation of these benefits to harder clinical outcomes. Most of our understanding on the iNO field in cardiac surgery stems from small observational or single centre randomised trials and even the very few multicentre trials fail to ascertain strong evidence base. As a consequence, there are only weak clinical practice guidelines on the field and only European expert opinion for the use of iNO in routine and more specialised cardiac surgery such as heart and lung transplantation and left ventricular assist device (LVAD) insertion. In this review the authors from a specialised cardiac centre in the UK with a very high volume of iNO usage provide detailed information on the early observations leading to the European expert recommendations and reflect on the nature and background of these recommendations. We also provide a summary of the progress in each of the cardiac subspecialties for the last decade and initial survey data on the views of senior anaesthetic and intensive care colleagues on these recommendations. We conclude that the combination of high price tag associated with iNO therapy and lack of substantial clinical evidence is not sustainable on the current field and we are risking loosing this promising therapy from our daily practice. Overcoming the status quo will not be easy as there is not much room for controlled trials in heart transplantation or in the current atmosphere of LVAD implantation. However, we call for international cooperation to conduct definite studies to determine the place of iNO therapy in lung transplantation and high risk mitral surgery. This will require new collaboration between the pharmaceutical companies, national grant agencies and the clinical community. Until these trials are realized we should gather multi-institutional experience from large retrospective studies and prospective data from a new international registry. We must step up international efforts if we wish to maintain the iNO modality in the armamentarium of hemodynamic tools for the perioperative management of our high risk cardiac surgical patients.

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.

Impella CP and ProtekDuo as a bridge to recovery following surgical revascularization complicated by electrical storm.

Short-term mechanical circulatory support (MCS) devices are designed to provide hemodynamic support for a wide range of clinical conditions such as high-risk cardiac surgery or interventional procedures, post-cardiotomy cardiogenic shock, acute decompensated heart failure. Electrical storm (defined as three or more sustained episodes of ventricular fibrillation-VF- in a 24-h period) is a rare but critical complication following revascularization in patients with ischemic heart disease and it is associated with a very high mortality (80-90%) both during the incident alone and during further observation. Here we report the case of a 38-year-old patient affected by coronary artery disease with moderate to severe left ventricular systolic dysfunction (EF 30-35%) who underwent emergency coronary artery bypass grafting (CABG) complicated by electrical storm and severe haemodynamic instability, successfully managed with a novel approach of biventricular mechanical circulatory support with extracorporeal life support (ECLS) in first instance, subsequently switched to Impella CP and ProtekDuo.

Lipid peroxidation in cardiac surgery: towards consensus on biomonitoring, diagnostic tools and therapeutic implementation.

This review focuses on oxidative stress and more specifically lipid peroxidation in cardiac surgery, one of the fundamental theories of perioperative complications. We present the molecular pathways leading to lipid peroxidation and integrate analytical methods that allow detection of lipid peroxidation markers in the fluid phase with those focusing on volatile compounds in exhaled breath. In order to explore the accumulated data in the literature, we present a systematic review of quantitative analysis of malondialdehyde, a widely used lipid peroxidation product at various stages of cardiac surgery. This exploration reveals major limitations of existing studies in terms of variability of reported values and significant gaps due to discrete and variable sampling times during surgery. We also appraise methodologies that allow real-time and continuous monitoring of oxidative stress. Complimentary techniques highlight that beyond the widely acclaimed contribution of the cardiopulmonary bypass technology and myocardial reperfusion injury, the use of diathermy contributes significantly to intraoperative lipid peroxidation. We conclude that there is an urgent need to implement the theory of oxidative stress towards a paradigm change in the clinical practice. Firstly, we need to acquire definite and irrefutable information on the link between lipid peroxidation and post-operative complications by building international consensus on best analytical approaches towards generating qualitatively and quantitatively comparable datasets in coordinated multicentre studies. Secondly, we should move away from routine low-risk surgeries towards higher risk interventions where there is major unmet clinical need for improving patient journey and outcomes. There is also need for consensus on best therapeutic interventions which could be tested in convincing large scale clinical trials. As future directions, we propose combination of fluid phase platforms and 'metabography', an extended form of capnography-including real-time analysis of lipid peroxidation and volatile footprints of metabolism-for better patient phenotyping prior to and during high risk surgery towards molecular prediction, stratification and monitoring of the patient's journey.

The role of interleukin-1ß as a predictive biomarker and potential therapeutic target during clinical ex vivo lung perfusion.

BACKGROUND: Extended criteria donor lungs deemed unsuitable for immediate transplantation can be reconditioned using ex vivo lung perfusion (EVLP). Objective identification of which donor lungs can be successfully reconditioned and will function well post-operatively has not been established. This study assessed the predictive value of markers of inflammation and tissue injury in donor lungs undergoing EVLP as part of the DEVELOP-UK study. METHODS: Longitudinal samples of perfusate, bronchoalveolar lavage, and tissue from 42 human donor lungs undergoing clinical EVLP assessments were analyzed for markers of inflammation and tissue injury. Levels were compared according to EVLP success and post-transplant outcomes. Neutrophil adhesion to human pulmonary microvascular endothelial cells (HPMECs) conditioned with perfusates from EVLP assessments was investigated on a microfluidic platform. RESULTS: The most effective markers to differentiate between in-hospital survival and non-survival post-transplant were perfusate interleukin (IL)-1ß (area under the curve = 1.00, p = 0.002) and tumor necrosis factor-α (area under the curve = 0.95, p = 0.006) after 30 minutes of EVLP. IL-1ß levels in perfusate correlated with upregulation of intracellular adhesion molecule-1 in donor lung vasculature (R2 = 0.68, p < 0.001) and to a lesser degree upregulation of intracellular adhesion molecule-1 (R2 = 0.30, p = 0.001) and E-selectin (R2 = 0.29, p = 0.001) in conditioned HPMECs and neutrophil adhesion to conditioned HPMECs (R2 = 0.33, p < 0.001). Neutralization of IL-1ß in perfusate effectively inhibited neutrophil adhesion to conditioned HPMECs (91% reduction, p = 0.002). CONCLUSIONS: Donor lungs develop a detectable and discriminatory pro-inflammatory signature in perfusate during EVLP. Blocking the IL-1ß pathway during EVLP may reduce endothelial activation and subsequent neutrophil adhesion on reperfusion; this requires further investigation in vivo.

Mechanical ventilation after lung transplantation.

INTRODUCTION: To explore the hypothesis that early ventilation strategies influence clinical outcomes in lung transplantation, we have examined our routine ventilation practices in terms of tidal volumes (Vt) and inflation pressures. METHODS: A total of 124 bilateral lung transplants between 2010 and 2013 were retrospectively assigned to low (<6 mL/kg), medium (6-8 mL/kg), and high (>8 mL/kg) Vt groups based on ventilation characteristics during the first 6 hours after surgery. Those same 124 patients were also stratified to low-pressure (<25 cm H2O) and high-pressure (≥25 cm H2O) groups. RESULTS: Eighty percent of patients were ventilated using pressure control mode. Low, medium, and high Vt were applied to 10%, 43%, and 47% of patients, respectively. After correcting for patients requiring extracorporeal support, there was no difference in short-term to midterm outcomes among the different Vt groups. Low inflation pressures were applied to 61% of patients, who had a shorter length of intensive care unit stay (5 vs 12 days; P = .012), higher forced expiratory volume in 1 second at 3 months (77.8% vs 60.3%; P < .001), and increased 6-month survival rate (95% vs 77%; P = .008). CONCLUSION: Low Vt ventilation has not been fully adopted in our practice. Ventilation with higher inflation pressures, but not Vt, was significantly associated with poorer outcomes after lung transplantation.

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.

Prognostic significance of left atrial volume dilatation in patients with hypertrophic cardiomyopathy.

To evaluate the prognostic role of left atrial (LA) volume in hypertrophic cardiomyopathy (HCM), LA volume was measured at baseline and during follow-up in 140 patients with HCM. Unfavorable outcome, defined as occurrence of sudden death, heart transplantation, or invasive reduction of obstruction, developed in 16 patients. In patients with enlarged LA volume (>27 mL/m(2)), there was an increased risk for unfavorable outcome (P = .0152). Patients with normal LA volume at baseline in whom volume increased more than 3 mL per year (fast dilating LA volume) had a worse prognosis than patients with normal and stable volume (P < .001) and similar to patients with dilated LA volume at baseline (P = not significant). LA volume dilated at baseline, fast dilating LA volume, and New York Heart Association functional class were independent predictors of unfavorable outcome development (odds ratio: 11.453; P = .021, P = 2.019, P = .020, respectively). The assessment of LA volume at baseline and during follow-up adds information regarding prognosis in patients with HCM.