Reflux Surgery in Lung Transplantation: A Multicenter Retrospective Study.

BACKGROUND: Aspiration has been associated with graft dysfunction after lung transplantation, leading some to advocate for selective use of fundoplication despite minimal data supporting this practice. METHODS: We performed a multicenter retrospective study at 4 academic lung transplant centers to determine the association of gastroesophageal reflux disease and fundoplication with bronchiolitis obliterans syndrome and survival using Cox multivariable regression. RESULTS: Of 542 patients, 136 (25.1%) underwent fundoplication; 99 (18%) were found to have reflux disease without undergoing fundoplication. Blanking the first year after transplantation, fundoplication was not associated with a benefit regarding freedom from bronchiolitis obliterans syndrome (hazard ratio [HR], 0.93; 95% CI, 0.58-1.49) or death (HR, 0.97; 95% CI, 0.47-1.99) compared with reflux disease without fundoplication. However, a time-dependent adjusted analysis found a slight decrease in mortality (HR, 0.59; 95% CI, 0.28-1.23; P = .157), bronchiolitis obliterans syndrome (HR, 0.68; 95% CI, 0.42-1.11; P = .126), and combined bronchiolitis obliterans syndrome or death (HR, 0.66; 95% CI, 0.42-1.04; P = .073) in the fundoplication group compared with the gastroesophageal reflux disease group. CONCLUSIONS: Although a statistically significant benefit from fundoplication was not determined because of limited sample size, follow-up, and potential for selection bias, a randomized, prospective study is still warranted.

Renin Angiotensin Aldosterone System Antagonism in 2019 Novel Coronavirus Acute Lung Injury.

It has been established that severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) uses angiotensin-converting enzyme 2 (ACE2), a membrane-bound regulatory peptide, for host cell entry. Renin-angiotensin-aldosterone system (RAAS) inhibitors have been reported to increase ACE2 in type 2 pneumocyte pulmonary tissue. Controversy exists for the continuation of ACE inhibitors, angiotensin II receptor blockers, and mineralocorticoid receptor antagonists in the current pandemic. ACE2 serves as a regulatory enzyme in maintaining homeostasis between proinflammatory angiotensin II and anti-inflammatory angiotensin 1,7 peptides. Derangements in these peptides are associated with cardiovascular disease and are implicated in the progression of acute respiratory distress syndrome. Augmentation of the ACE2/Ang 1,7 axis represents a critical target in the supportive management of coronavirus disease 2019-associated lung disease. Observational data describing the use of RAAS inhibitors in the setting of SARS-CoV-2 have not borne signals of harm to date. However, equipoise persists, requiring an analysis of novel agents including recombinant human-ACE2 and existing RAAS inhibitors while balancing ongoing controversies associated with increased coronavirus infectivity and virulence.

Results From the United States Chronic Thromboembolic Pulmonary Hypertension Registry: Enrollment Characteristics and 1-Year Follow-up.

BACKGROUND: The United States Chronic Thromboembolic Pulmonary Hypertension Registry (US-CTEPH-R) was designed to characterize the demographic characteristics, evaluation, clinical course, and outcomes of surgical and nonsurgical therapies for patients with chronic thromboembolic pulmonary hypertension. RESEARCH QUESTION: What are the differences in baseline characteristics and 1-year outcomes between operated and nonoperated subjects? STUDY DESIGN AND METHODS: This study describes a multicenter, prospective, longitudinal, observational registry of patients newly diagnosed (< 6 months) with CTEPH. Inclusion criteria required a mean pulmonary artery pressure ≥ 25 mm Hg documented by right heart catheterization and radiologic confirmation of CTEPH. Between 2015 and 2018, a total of 750 patients were enrolled and followed up biannually until 2019. RESULTS: Most patients with CTEPH (87.9%) reported a history of acute pulmonary embolism. CTEPH diagnosis delays were frequent (median, 10 months), and most patients reported World Health Organization functional class 3 status at enrollment with a median mean pulmonary artery pressure of 44 mm Hg. The registry cohort was subdivided into Operable patients undergoing pulmonary thromboendarterectomy (PTE) surgery (n = 566), Operable patients who did not undergo surgery (n = 88), and those who were Inoperable (n = 96). Inoperable patients were older than Operated patients; less likely to be obese; have a DVT history, non-type O blood group, or thrombophilia; and more likely to have COPD or a history of cancer. PTE resulted in a median pulmonary vascular resistance decline from 6.9 to 2.6 Wood units (P < .001) with a 3.9% in-hospital mortality. At 1-year follow-up, Operated patients were less likely treated with oxygen, diuretics, or pulmonary hypertension-targeted therapy compared with Inoperable patients. A larger percentage of Operated patients were World Health Organization functional class 1 or 2 at 1 year (82.9%) compared with the Inoperable (48.2%) and Operable/No Surgery (56%) groups (P < .001). INTERPRETATION: Differences exist in the clinical characteristics between patients who exhibited operable CTEPH and those who were inoperable, with the most favorable 1-year outcomes in those who underwent PTE surgery. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov; No.: NCT02429284; URL: www.clinicaltrials.gov.

The United States Chronic Thromboembolic Pulmonary Hypertension Registry: Protocol for a Prospective, Longitudinal Study.

BACKGROUND: Chronic thromboembolic pulmonary hypertension (CTEPH) is a rare sequela of acute pulmonary embolism that is treatable when recognized. Awareness of this disease has increased with recent advancements in therapeutic options, but delays in diagnosis remain common, and diagnostic and treatment guidelines are often not followed. Data gathered from international registries have improved our understanding of CTEPH, but these data may not be applicable to the US population owing to differences in demographics and medical practice patterns. OBJECTIVE: The US CTEPH Registry (US-CTEPH-R) was developed to provide essential information to better understand the demographics, risk factors, evaluation, and treatment of CTEPH in the United States, as well as the short- and long-term outcomes of surgical and nonsurgical therapies in the modern treatment era. METHODS: Thirty sites throughout the United States enrolled 750 subjects in this prospective, longitudinal, observational registry of patients newly diagnosed with CTEPH. Enrollment criteria included a mean pulmonary artery pressure ≥25 mmHg by right heart catheterization and radiologic confirmation of CTEPH by a multidisciplinary adjudication committee. Following enrollment, subjects were followed biannually until the conclusion of the study. Quality of life surveys were administered at enrollment and biannually, and all other testing was at the discretion of the treating clinician. Details regarding surgical therapy, balloon pulmonary angioplasty, and medical therapy were collected at enrollment and at follow-up, as well as information related to health care utilization and survival. RESULTS: Data from this registry will improve understanding of the demographics, risk factors, and treatment patterns of patients with CTEPH, and the longitudinal impact of therapies on quality of life, health care utilization, and survival. CONCLUSIONS: This manuscript details the methodology and design of the first large, prospective, longitudinal registry of patients with CTEPH in the United States. TRIAL REGISTRATION: ClinicalTrials.gov NCT02429284; https://www.clinicaltrials.gov/ct2/show/NCT02429284. INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID): DERR1-10.2196/25397.

Extended post-ex vivo lung perfusion cold preservation predicts primary graft dysfunction and mortality: Results from a multicentric study.

BACKGROUND: Ex vivo lung perfusion (EVLP) allows for a reassessment of lung grafts initially deemed unsuitable for transplantation, increasing the available donor pool; however, this requires a pre- and post-EVLP period of cold ischemic time (CIT). Paucity of data exists on how the sequence of cold normothermic-cold preservations affect outcomes. METHODS: A total of 110 patients were retrospectively analyzed. Duration of 3 preservation phases was measured: cold pre-EVLP, EVLP, and cold post-EVLP. The donor and recipient clinical data were collected. Primary graft dysfunction (PGD) and survival were monitored. Risk of mortality or PGD was calculated using Cox proportional hazards and logistic regression models to adjust for baseline characteristics. RESULTS: Using the highest quartile, patients were stratified into extended vs non-extended pre-EVLP (<264 vs ≥264 minutes) and post-EVLP (<287 vs ≥287 minutes) CIT. The rates of 1-year mortality (8.4% vs 29.6%, p = 0.013), PGD 2-3 (20.5% vs 52%, p = 0.002), and PGD 3 (8.4% vs 29.6%, p = 0.005) at 72 hours were increased in the extended post-EVLP CIT group. After adjusting for baseline risk factors, the extended group remained an independent predictor of PGD ≥2 (odd ratio: 6.18, 95% CI: 1.88-20.3, p = 0.003) and PGD 3 (odd ratio: 20.4, 95% CI: 2.56-161.9, p = 0.004) at 72 hours and 1-year mortality (hazard ratio: 17.9, 95% CI: 3.36-95.3, p = 0.001). Cold pre-EVLP was not a significant predictor of primary outcomes. CONCLUSIONS: Extended cold post-EVLP preservation is associated with a risk for PGD and 1-year mortality. Pre-EVLP CIT does not increase mortality or high-grade PGD. These findings from a multicenter trial should caution on the implementation of extended cold preservation after EVLP.

Poor Performance Flagging Is Associated With Fewer Transplantations at Centers Flagged Multiple Times.

BACKGROUND: Lung transplantation outcomes are heavily scrutinized, given the high stakes of these operations, yet the Center for Medicare and Medicaid Services (CMS) method of using Scientific Registry of Transplant Recipients (SRTR) risk-adjusted outcomes to identify underperforming centers is controversial. We hypothesized that CMS flagging results in conservative behavior for recipient and organ selection, resulting in fewer patients added to the waitlist and fewer transplantations performed. METHODS: SRTR reports from July 2012 through July 2017 were included. Center characteristics were compared, stratified by number of flagging events. The impact of flagging for underperformance on risk aversion outcomes was analyzed using a mixed-effects regression model. RESULTS: A total of 72 centers had reported SRTR data during the study period. Of these, 21 centers (29%) met flagging criteria a median of 2 times (interquartile range, 1 to 4 times) for a total of 53 events. Flagging had no statistically significant impact on waitlist or transplantation volume and patient selection by mixed-effects modeling. Despite similar average expected 1-year survival (86.6% versus 87.7%, p = 0.27), centers that were flagged only once added more patients per year to the waitlist (16.3 patients versus 7.8 patients, p = 0.01) and performed more transplantations per year (28.4 transplantations versus 11.1 transplantations, p = 0.01). CONCLUSIONS: This analysis defines center-level trends in lung transplantation after CMS flagging. Contrary to our primary hypothesis, flagging did not result in temporal center-level changes. However, programs on prolonged probation demonstrated reduced activity, which likely indicates a shift to higher performing centers.

Survival after lung transplantation in recipients with alpha-1-antitrypsin deficiency compared to other forms of chronic obstructive pulmonary disease: a national cohort study.

Alpha-1-antitrypsin deficiency (AATD) is grouped with chronic obstructive pulmonary disease (COPD); however, this may not be appropriate. This study assessed whether AATD confers a different prognosis than COPD following lung transplantation. We employed the United Network for Organ Sharing (UNOS) database, grouping patients by diagnoses of AATD or COPD. Kaplan-Meier methods and Cox modeling were performed to determine the association of diagnosis and overall survival. Of 9569 patients, 1394 (14.6%) had a diagnosis of AATD. Patients with AATD who received a single-lung transplant had reduced 1-year survival [adjusted hazard ratio (AHR): 1.68, 95% CI: 1.26, 2.23]. Among patients who received a bilateral lung transplant, there was no significant difference in survival by diagnosis (AHR for AATD as compared to COPD: 0.96, 95% CI: 0.82, 1.12). After the implementation of the lung allocation score (LAS), there was no significant difference in survival among patients who received a single (AHR: 1.15, 95% CI: 0.69, 1.95) or bilateral (AHR: 0.99, 95% CI: 0.73, 1.34) lung transplant by diagnosis. Lung transplantation is increasingly employed in the care of the patient with COPD. Although recipients undergoing LTX for AATD are at increased risk of both acute rejection and airway dehiscence post-transplant, in the post-LAS era, survival rates are similar for recipients with AATD in comparison with COPD.

The association of donor age and survival is independent of ischemic time following deceased donor lung transplantation.

PURPOSE: Early research suggests prolonged ischemic time in older donor lungs is associated with decreased survival following lung transplantation. The purpose of this study was to determine whether this association holds in the post-lung allocation score era. METHODS: We analyzed the United Network for Organ Sharing database 2005-2013 for adult recipients of cadaveric lung transplants. Cox proportional hazards modeling was utilized to determine the association of donor age, ischemic time, and the interaction of donor age and ischemic time with transplant-free survival. RESULTS: Eleven thousand eight hundred thirty-five patients met criteria. Median donor age was 32 years, and median ischemic time was 4.9 hours. Cox modeling demonstrated that donor age 50-60 (adjusted hazard ratio (HR): 1.11) and ≥60 (adjusted HR: 1.42) were associated with reduced overall survival. Neither ischemic time nor interaction of ischemic time and donor age were significantly associated with overall survival. Subanalysis demonstrated that this finding held true for patients undergoing either single or bilateral lung transplantation. CONCLUSIONS: Prolonged ischemic time is not associated with decreased overall survival in patients undergoing lung transplantation regardless of the donor's age. However, donor age >50 is independently associated with decreased survival. The lack of an association between ischemic time and survival should encourage broader geographic allocation of pulmonary allografts.

The utility of 6-minute walk distance in predicting waitlist mortality for lung transplant candidates.

BACKGROUND: The lung allocation score (LAS) has led to improved organ allocation for transplant candidates. At present, the 6-minute walk distance (6MWD) is treated as a binary categorical variable of whether or not a candidate can walk more than 150 feet in 6 minutes. In this study, we tested the hypothesis that 6MWD is presently under-utilized with respect to discriminatory power, and that, as a continuous variable, could better prognosticate risk of waitlist mortality. METHODS: A retrospective cohort analysis was performed using the Organ Procurement and Transplantation Network/United Network for Organ Sharing (OPTN/UNOS) transplant database. Candidates listed for isolated lung transplant between May 2005 and December 2011 were included. The population was stratified by 6MWD quartiles and unadjusted survival rates were estimated. Multivariable Cox proportional hazards modeling was used to assess the effect of 6MWD on risk of death. The Scientific Registry of Transplant Recipients (SRTR) Waitlist Risk Model was used to adjust for confounders. The optimal 6MWD for discriminative accuracy in predicting waitlist mortality was assessed by receiver-operating characteristic (ROC) curves. RESULTS: Analysis was performed on 12,298 recipients. Recipients were segregated into quartiles by distance walked. Waitlist mortality decreased as 6MWD increased. In the multivariable model, significant variables included 6MWD, male gender, non-white ethnicity and restrictive lung diseases. ROC curves discriminated 6-month mortality was best at 655 feet. CONCLUSIONS: The 6MWD is a significant predictor of waitlist mortality. A cut-off of 150 feet sub-optimally identifies candidates with increased risk of mortality. A cut-off between 550 and 655 feet is more optimal if 6MWD is to be treated as a dichotomous variable. Utilization of the LAS as a continuous variable could further enhance predictive capabilities.

Spontaneously Breathing Extracorporeal Membrane Oxygenation Support Provides the Optimal Bridge to Lung Transplantation.

BACKGROUND: Extracorporeal membrane oxygenation (ECMO) is being increasingly used as a bridge to lung transplantation. Small, single-institution series have described increased success using ECMO in spontaneously breathing patients compared with patients on ECMO with mechanical ventilation, but this strategy has not been evaluated on a large scale. METHODS: Using the United Network for Organ Sharing database, all adult patients undergoing isolated lung transplantation from May 2005 through September 2013 were identified. Patients were categorized by their type of pretransplant support: no support, ECMO only, invasive mechanical ventilation (iMV) only, and ECMO + iMV. Kaplan-Meier survival analysis with log-rank testing was performed to compare survival based on type of preoperative support. A Cox regression model was used to determine whether type of preoperative support was independently associated with survival, using previously established predictors of survival as covariates. RESULTS: Approximately 12,403 primary adult pulmonary transplantations were included in this analysis. Sixty-five patients (0.52%) were on ECMO only, 612 (4.93%) required only iMV, 119 (0.96%) were on ECMO + iMV, and the remaining 11,607 (94.6%) required no invasive support before transplantation. One-year survival was decreased in all patients requiring support, regardless of type. However, mid-term survival was similar between patients on ECMO alone and those not on support but significantly worse with patients requiring iMV only or ECMO + iMV. In multivariable analysis, ECMO + iMV and iMV alone were independently associated with decreased survival compared with nonsupport patients, whereas ECMO alone was not significant. CONCLUSIONS: In patients with worsening pulmonary disease awaiting lung transplantation, those supported via ECMO with spontaneous breathing demonstrated improved survival compared with other bridging strategies.

Clearance of bile and trypsin in rat lungs following aspiration of human gastric fluid.

PURPOSE: In the clinical setting, there is no reliable tool for diagnosing gastric aspiration. A potential way of diagnosing gastric fluid aspiration entails bronchoalveolar lavage (BAL) with subsequent examination of the BAL fluid for gastric fluid components that are exogenous to the lungs. The objective of this study was to determine the longevity of the gastric fluid components bile and trypsin in the lung, in order to provide an estimate of the time frame in which assessment of these components in the BAL might effectively be used as a measure of aspiration. MATERIALS AND METHODS: Human gastric fluid (0.5 mg/kg) was infused in the right lung of intubated male Fischer 344 rats (n = 30). Animals were sacrificed at specified times following the experimentally induced aspiration, and bronchoalveolar lavage fluid (BALF) was collected. Bile concentrations were analyzed by an enzyme-linked chromatogenic method, and the concentration of trypsin was quantified using an ELISA. Data were analyzed using non-linear regression and a one-phase decay equation. RESULTS: In this experimental model, the half-life of bile was 9.3 hours (r(2) = 0.81), and the half-life of trypsin was 9.0 hours (r(2) = 0.68). CONCLUSIONS: The half-lives of bile and trypsin in the rodent aspiration model suggest that the ability to detect aspiration may be limited to a few days post-aspiration. If studies using rats are any indication, it may be most effective to collect BAL samples within the first 24 hours of suspected aspiration events in order to detect aspiration.

The role of soluble and insoluble gastric fluid components in the pathogenesis of obliterative bronchiolitis in rat lung allografts.

Repetitive gastric fluid aspirations have been shown to lead to obliterans bronchiolitis (OB), but the component or components of gastric fluid that are responsible are unknown. This study investigates the role of particulates and, separately, soluble material in gastric fluid during the development of OB. Whole gastric fluid (WGF) was collected from male Fischer 344 (F344) rats and separated by centrifugation into particle reduced gastric fluid (PRGF) and particulate components resuspended in normal saline (PNS). Orthotopic left lung transplants from male Wistar-Kyoto rats into F344 rats were performed using a modification of the nonsuture external cuff technique with prolonged cold ischemia. Rats were subjected to weekly aspiration of 0.5 ml/kg of WGF (n = 9), PRGF (n = 10), PNS (n = 9), or normal saline (control, NS; n = 9) for 8 weeks following transplantation. Lung allografts treated with WGF, PRGF, or PNS developed a significantly greater percentage of OB-like lesions compared with the control. No statistical difference was observed when comparing the fibrosis grades or the percentage of OB lesions of WGF, PRGF, and PNS groups, suggesting that both soluble and insoluble components of gastric fluid can promote the development of aspiration-induced OB and fibrosis in lung allografts.

Economic Outcomes of Extracorporeal Membrane Oxygenation With and Without Ambulation as a Bridge to Lung Transplantation.

BACKGROUND: An increasing number of centers are using active rehabilitation and ambulation for critically ill patients on extracorporeal membrane oxygenation (ECMO) as a bridge to lung transplantation. This investigation assessed the economic impact at a single center of ambulatory versus non-ambulatory ECMO strategies as a bridge to lung transplantation. METHODS: We conducted a single-center retrospective cohort analysis of all subjects supported with ECMO as a bridge to lung transplantation (N = 9) from 2007 to 2012. Subjects who were rehabilitated while supported with ECMO before lung transplantation were compared with those who were not rehabilitated during ECMO. Hospital cost data for the month before transplantation through 12 months after the initial post-transplant hospital discharge were compared. RESULTS: The median cost (interquartile range [IQR]) in the 30 d before transplant for the ambulatory cohort was $88,137 (IQR $38,589-$122,111) compared with $52,124 (IQR $23,824-$69,929) for the non-ambulatory cohort (P = .08). The median post-transplant ICU cost for the ambulatory cohort was $38,468 (IQR $23,611-$64,126) compared with $143,407 (IQR $112,199-$168,993) for the non-ambulatory cohort (P = .01). The median total hospital cost for subjects supported with ambulatory ECMO was $213,086 (IQR $166,767-$264,536) compared with $273,291 (IQR $237,299-$374,175) for non-ambulatory ECMO subjects (P = .05). The median total cost for the ambulatory cohort was $268,194 (IQR $219,972-$517,320) compared with $300,307 (IQR $274,262-$394,913) for the non-ambulatory cohort (P = .14). CONCLUSIONS: Subjects supported with ambulatory ECMO had a 22% ($60,204) reduction in total hospital cost, 73% ($104,939) reduction in post-transplant ICU cost, and 11% ($32,133) reduction in total cost compared with non-ambulatory ECMO subjects. This analysis demonstrates the potential economic benefit of rehabilitation and ambulation during ECMO compared with a traditional strategy.

Impact of donor and recipient hepatitis C status in lung transplantation.

BACKGROUND: Studies of lung transplantation in the setting of donors or recipients with hepatitis C virus (HCV) have been limited but have raised concerns about outcomes associated with this infection. METHODS: Lung transplant cases in the United Network for Organ Sharing (UNOS) database from 1994 to 2011 were analyzed for the HCV status of both donor and recipient. First, among HCV-negative recipients, those who received a lung from an HCV-positive donor (HCV(+) D) were compared with those who received an HCV-negative lung (HCV(-) D). Donor, recipient and operative characteristics as well as outcomes were compared between groups, and overall survival was compared after adjustment for confounders. In a second analysis, HCV-positive recipients (HCV(+) R) were compared with HCV-negative recipients (HCV(-) R). The analysis was stratified by era (1994 to 1999 and 2000 to 2011) and long-term survival was compared. RESULTS: Of 16,604 HCV-negative patients in the UNOS database, 28 (0.2%) received a lung from an HCV(+) D, with use of HCV(+) D decreasing significantly over time. Overall survival (OS) was shorter in the HCV(+) D group (median survival: 1.3 vs 5.1 years; p = 0.002). Results were confirmed in adjusted analyses. After inclusion criteria were met, 289 (1.7%) of the lung transplant recipients were HCV(+) R. These patients appeared similar to their HCV(-) R counterparts, except they were older and had more limited functional status. OS was significantly lower in HCV-positive individuals during the early era (median survival: 1.7 vs 4.5 years; p = 0.004), but not the recent era (median survival: 4.4 vs 5.4 years; p = 0.100). Again, results were confirmed by adjusted analysis. CONCLUSIONS: HCV-positive status is a rare problem when considering both lung recipients and donors. Current data demonstrate significantly worse outcomes for HCV-negative patients receiving an HCV(+) lung; however, since 2000, HCV(+) recipients undergoing lung transplantation appear to have survival approximating that of HCV(-) recipients, an improvement from previous years. Recent medical advances in treatment for HCV may further improve outcomes in these groups.

What Is the Optimal Transplant for Older Patients With Idiopathic Pulmonary Fibrosis?

BACKGROUND: There is controversy regarding the optimal type of lung transplant--single orthotopic lung transplantation (SOLT) versus bilateral orthotopic lung transplantation (BOLT)--for patients with idiopathic pulmonary fibrosis. We performed this study to determine which type of transplant is more appropriate for older patients with this condition. METHODS: We conducted a review of the United Network for Organ Sharing database from 2005 to 2013 for patients aged 65 years or more with idiopathic pulmonary fibrosis. A 1:1 nearest-neighbor propensity match was utilized to determine differences in survival by transplant procedure type (SOLT versus BOLT). Logistic regression modeling taking into account interaction terms between prespecified variables and the type of transplant was utilized to determine variables that altered the survival outcomes associated with SOLT versus BOLT. RESULTS: Of 1,564 patients who met study criteria, 521 (33.3%) received BOLT. After propensity matching 498 BOLT recipients to 498 SOLT recipients, BOLT was associated with a significantly improved 5-year survival (48.7% versus 35.2%, p < 0.01). However, the mortality hazard associated with BOLT varied from a nonsignificant reduction in survival within 3 months after transplant (hazard ratio 1.24, 95% confidence interval: 0.80 to 1.93) to a significant survival benefit for patients who survived beyond 1 year (hazard ratio 0.64, 95% confidence interval: 0.47 to 0.86). Functional status was also found to be a significant predictor of the survival benefit associated with BOLT. CONCLUSIONS: Bilateral orthotopic lung transplantation is associated with significantly improved survival over SOLT for older patients with idiopathic pulmonary fibrosis, driven by a late survival benefit from bilateral transplantation. However, patients with a reduced preoperative functional status do not appear to derive a similar benefit from bilateral transplantation.

The utility of preoperative six-minute-walk distance in lung transplantation.

RATIONALE: The use of 6-minute-walk distance (6MWD) as an indicator of exercise capacity to predict postoperative survival in lung transplantation has not previously been well studied. OBJECTIVES: To evaluate the association between 6MWD and postoperative survival following lung transplantation. METHODS: Adult, first time, lung-only transplantations per the United Network for Organ Sharing database from May 2005 to December 2011 were analyzed. Kaplan-Meier methods and Cox proportional hazards modeling were used to determine the association between preoperative 6MWD and post-transplant survival after adjusting for potential confounders. A receiver operating characteristic curve was used to determine the 6MWD value that provided maximal separation in 1-year mortality. A subanalysis was performed to assess the association between 6MWD and post-transplant survival by disease category. MEASUREMENTS AND MAIN RESULTS: A total of 9,526 patients were included for analysis. The median 6MWD was 787 ft (25th-75th percentiles = 450-1,082 ft). Increasing 6MWD was associated with significantly lower overall hazard of death (P < 0.001). Continuous increase in walk distance through 1,200-1,400 ft conferred an incremental survival advantage. Although 6MWD strongly correlated with survival, the impact of a single dichotomous value to predict outcomes was limited. All disease categories demonstrated significantly longer survival with increasing 6MWD (P ≤ 0.009) except pulmonary vascular disease (P = 0.74); however, the low volume in this category (n = 312; 3.3%) may limit the ability to detect an association. CONCLUSIONS: 6MWD is significantly associated with post-transplant survival and is best incorporated into transplant evaluations on a continuous basis given limited ability of a single, dichotomous value to predict outcomes.

An assessment of human gastric fluid composition as a function of PPI usage.

The standard of care for chronic gastro-esophageal reflux disease (GERD), which affects up to 40% of the population, is the use of drugs such as proton pump inhibitors (PPIs) that block the production of stomach acid. Despite widespread use, the effects of PPIs on gastric fluid remain poorly characterized. In this study, gastric fluid was collected from patients undergoing cardiac surgery who were not (n = 40) or were (n = 25) actively taking PPIs. Various enzymatic and immunoassays as well as mass spectrometry were utilized to analyze the concentrations of bile, gastricsin, trypsin, and pepsin in the gastric fluid. Proteomic analyses by mass spectrometry suggested that degradation of trypsin at low pH might account, at least in part, for the observation that patients taking PPIs have a greater likelihood of having high concentrations of trypsin in their gastric fluid. In general, the concentrations of all analytes evaluated varied over several orders of magnitude, covering a minimum of a 2000-fold range (gastricsin) and a maximum of a 1 × 10(6) -fold range (trypsin). Furthermore, the concentrations of various analytes were poorly correlated with one another in the samples. For example, trypsin and bile concentrations showed a significant (P < 0.0001) but not strong correlation (r = 0.54). Finally, direct assessment of bacterial concentrations by flow cytometry revealed that PPIs did not cause a profound increase in microbial load in the gastric fluid. These results further delineate the profound effects that PPI usage has on the physiology of the stomach.

Reflux and allograft dysfunction: is there a connection?

Despite improving outcomes following lung transplantation, chronic rejection continues to limit survival. The predominant form of chronic rejection, bronchiolitis obliterans syndrome, has been associated with multiple etiologies including aspiration from gastroduodenal reflux. This article reviews the current literature with regards to the incidence of reflux following lung transplantation, the association of reflux with allograft dysfunction and survival, and the success of prevention and treatment of reflux in this patient population. Although antireflux surgery has been demonstrated to be safe in this population and leads to a stabilization of lung function in patients with reflux, there have not been definitive data that it improves survival.