The current practice in the diagnostic work-up of patients with hemoptysis of unknown etiology: an international survey.

BACKGROUND: Hemoptysis is a challenging and potentially life-threatening medical condition. The most appropriate diagnostic work-up is debated and several diagnostic approaches are implemented worldwide. METHODS: An international, online survey was carried out to investigate the current practice of the diagnostic work-up of patients with hemoptysis of unknown etiology. RESULTS: overall, 604 physicians responded to the survey. At baseline, chest X-ray was suggested as the first diagnostic investigation by 342 (56.6%) participants. Computed tomography (CT) was suggested in each patient with non- and life-threatening hemoptysis by 310 (51.3%) and 526 (87.1%) respondents, respectively. Contrast-enhanced CT is the currently preferred technique (333, 55.1%). In case of patchy ground glass opacities and negative CT, 287 (47.5%) and 222 (36.8%) participants, respectively, would always offer bronchoscopy. Otorhinolaryngological evaluation was mostly suggested in case of suspected upper airways bleeding before other investigations (212, 35.1%). A follow-up was recommended for idiopathic hemoptysis by the majority of the participants (316, 52.3%). A multidisciplinary assessment is deemed crucial for each patient with life-threatening hemoptysis (437, 72.4%). CONCLUSIONS: Chest X-ray and contrast-enhanced CT are currently preferred as the first diagnostic investigations, regardless of hemoptysis severity. Bronchoscopy is suggested in case of negative radiological examination and when CT shows only ground glass opacities. Otorhinolaryngological evaluation is advised before any other investigations when upper airways bleeding is suspected. Patients with idiopathic hemoptysis are suggested to undergo a clinical follow-up and in case of life-threatening bleeding a multidisciplinary assessment is deemed crucial. Due to the heterogeneous approaches a consensus statement would be needed.

Exacerbation Burden in COPD and Occurrence of Mortality in a Cohort of Italian Patients: Results of the Gulp Study.

Objective: To describe the burden of moderate to severe exacerbations and all-cause mortality; the secondary objectives were to analyze treatment patterns and changes over follow-up. Design: Observational, multicenter, retrospective, cohort study with a three year follow-up period. Setting: Ten Italian academic secondary- and tertiary-care centers. Participants: Patients with a confirmed diagnosis of COPD referring to the outpatient clinics of the participating centers were retrospectively recruited. Primary and Secondary Outcome Measures: Annualized frequency of moderate and severe exacerbations stratified by exacerbation history prior to study enrollment. Patients were classified according to airflow obstruction, GOLD risk categories, and divided in 4 groups: A = no exacerbations; B = 1 moderate exacerbation; C = 1 severe exacerbation; D = ≥2 moderate and/or severe exacerbations. Overall all-cause mortality stratified by age, COPD category, and COPD therapy. A logistic regression model assessed the association of clinical characteristics with mortality. Results: 1111 patients were included (73% males), of which 41.5% had a history of exacerbations. As expected, the proportion of patients experiencing ≥1 exacerbation during follow-up increased according to pre-defined study risk categories (B: 79%, C: 84%, D: 97.4%). Overall, by the end of follow-up, 45.5% of patients without a history of exacerbation experienced an exacerbation (31% of which severe), and 13% died. Deceased patients were significantly older, more obstructed and hyperinflated, and more frequently active smokers compared with survivors. Severe exacerbations were more frequent in patients that died (23.5%, vs 10.2%; p-value: 0.002). Chronic heart failure and ischemic heart disease were the only comorbidities associated with a higher odds ratio (OR) for death (OR: 2.2, p-value: 0.001; and OR: 1.9, p-value: 0.007). Treatment patterns were similar in patients that died and survivors. Conclusion: Patients with a low exacerbation risk are exposed to a significant future risk of moderate/severe exacerbations. Real life data confirm the strong association between mortality and cardiovascular comorbidities in COPD.

Effectiveness of a new "focused pulse" high-frequency chest wall oscillation in patients with moderate to severe COPD.

BACKGROUND: Chest physiotherapy plays a crucial role in the treatment of COPD, although the optimal techniques for airway clearance have not been definitively established. Among the different techniques, high-frequency chest wall oscillation (HFCWO) has gained attention for its potential to create a widespread lung percussion, facilitating the removal of secretions and potentially clearing the peripheral bronchial tree. This study aims to assess the effectiveness of a novel "focused pulse" HFCWO in patients with moderate to severe COPD. METHODS: Sixty patients were randomized to three groups: a group treated with the PEP technique, a group with "focused pulse "HFCWO" and a group with pharmacological therapy alone (control group). The primary outcomes were changes in respiratory function parameters, changes in dyspnea and quality of life scores as well as daily life activity and health status assessment. The secondary outcomes were the number of exacerbations and the number of practitioner or emergency department (ED) visits after 1, 3, and 6 months. RESULTS: Sixty patients concluded the study with 20 patients allocated to each group. The two devices improved respiratory function tests, quality of life and health scores and dyspnea compared to the control group. Maximal expiratory pressure and diffusing lung carbon oxide were significantly improved in the focused pulse HFCWO group compared to the PEP group. Only pulse-focused HFCWO showed a statistically significant lower number of exacerbations and visits to ED or practitioner compared to the control group. CONCLUSIONS: The focused pulse HFCWO technique improves daily life activities and lung function in patients with stable COPD. The device demonstrated significantly greater effectiveness in lowering COPD exacerbations as well as visits to ED or practitioner.

The pathogenesis of OSA-related hypertension: what are the determining factors?

Sleep-disordered breathing has a relatively high prevalence, which varies from 3-7% in males and from 2-5% in females in the adult population. Studies published in the literature have shown that sleep apnea is closely related to an increased risk of developing various pathologies, among which arterial hypertension stands out. The prevalence of hypertension in patients suffering from obstructive sleep apnea (OSA) ranges from 35-80% and appears to be related to OSA severity. Approximately 40-50% of patients affected by hypertension are also affected by OSA and this association seems to be stronger in young and middle-aged adults (<50 years of age). The primary objective of this narrative review is to provide an update on what are the main contributing comorbidities to the development of a hypertensive state in patients suffering from OSA, an independent risk factor for diurnal hypertension, implicated as a risk factor for the first stroke, recurrent stroke, and post-stroke mortality. There are a lot of factors that contribute to developing a hypertensive state in OSA patients, some more decisive, others less. More evidence from longitudinal studies is needed on the impact of OSA on cardiovascular risk in females, on the causal link between OSA and arterial hypertension or metabolic diseases, like diabetes and glucose intolerance, and the effect of different kinds of OSA treatment.

Correlation between high-resolution computed tomography appearance and histopathological features in the diagnosis of interstitial lung diseases. A real-life study.

BACKGROUND: According to current guidelines, a surgical biopsy is rarely required when a high-confidence radiologic interstitial lung disease (ILD) diagnosis is made on thin-section high-resolution computed tomography (HRCT). Nevertheless, disowning HRCT scans diagnosed by biopsy are more common than presumed. Our study aimed to describe the concordance rate between HRCT scans and pathological diagnoses of ILDs obtained by surgical biopsy. The current guideline suggests the use of surgical lung biopsy (SLB) in patients with newly detected ILD of unknown cause. METHODS: Patients who underwent mini-invasive surgical biopsies for interstitial lung diseases from January 2018 to August 2022 were analyzed. The HRCT scans were reviewed by an observer blinded to the patient's clinical information. The concordance between histological and HRCT-scan were assessed. RESULTS: Data from 104 patients with uncertain low confidence diagnosis of interstitial lung diseases at HRCT were analyzed. Most of the patients are male (65; 62.5%). The more frequent HRCT pattern were: alternative diagnoses (46; 44.23%), UIP probable (42; 40.38%), UIP indeterminate (7; 6.73%), and non-specific interstitial pneumonia (NSIP) (9, 8.65%). The more common histological diagnosis was UIP definite (30; 28.84%), hypersensitivity pneumonia [HP](19; 18.44%), NSIP (15; 14.42%), sarcoidosis (10; 9.60%). In 7 (20%) cases, the final pathological finding denies HRCT-scans diagnoses; indeed, a moderate agreement was observed between HRCT-scan findings and the definitive histological diagnosis (kappa index: 0.428). CONCLUSIONS: HRCT-scan has limitations if the objective is to define interstitial lung diseases accurately. Consequently, pathological assessment should be taken into account in order to provide more accurate tailored treatment strategies because the risk is to wait from 12 to 24 months to ascertain if the ILD will be treatable as progressive pulmonary fibrosis (PPF). Undeniably true, video-assisted surgical lung biopsy (VASLB) with endotracheal intubation and mechanical ventilation is associated with a risk of mortality and morbidity that is far from nil. Nevertheless, in recent years a VASLB approach performed in awake subjects under loco-regional anesthesia (awake-VASLB) has been suggested as an effective method to obtain a highly confident diagnosis in patients with diffuse pathologies of the lung parenchyma.

Herpes Virus Infection in Lung Transplantation: Diagnosis, Treatment and Prevention Strategies.

Lung transplantation is an ultimate treatment option for some end-stage lung diseases; due to the intense immunosuppression needed to reduce the risk of developing acute and chronic allograft failure, infectious complications are highly incident. Viral infections represent nearly 30% of all infectious complications, with herpes viruses playing an important role in the development of acute and chronic diseases. Among them, cytomegalovirus (CMV) is a major cause of morbidity and mortality, being associated with an increased risk of chronic lung allograft failure. Epstein-Barr virus (EBV) is associated with transformation of infected B cells with the development of post-transplantation lymphoproliferative disorders (PTLDs). Similarly, herpes simplex virus (HSV), varicella zoster virus and human herpesviruses 6 and 7 can also be responsible for acute manifestations in lung transplant patients. During these last years, new, highly sensitive and specific diagnostic tests have been developed, and preventive and prophylactic strategies have been studied aiming to reduce and prevent the incidence of these viral infections. In this narrative review, we explore epidemiology, diagnosis and treatment options for more frequent herpes virus infections in lung transplant patients.

Antiviral Approach to Cytomegalovirus Infection: An Overview of Conventional and Novel Strategies.

Human cytomegalovirus (HCMV) is a herpesvirus capable of establishing a lifelong persistence in the host through a chronic state of infection and remains an essential global concern due to its distinct life cycle, mutations, and latency. It represents a life-threatening pathogen for immunocompromised patients, such as solid organ transplanted patients, HIV-positive individuals, and hematopoietic stem cell recipients. Multiple antiviral approaches are currently available and administered in order to prevent or manage viral infections in the early stages. However, limitations due to side effects and the onset of antidrug resistance are a hurdle to their efficacy, especially for long-term therapies. Novel antiviral molecules, together with innovative approaches (e.g., genetic editing and RNA interference) are currently in study, with promising results performed in vitro and in vivo. Since HCMV is a virus able to establish latent infection, with a consequential risk of reactivation, infection management could benefit from preventive treatment for critical patients, such as immunocompromised individuals and seronegative pregnant women. This review will provide an overview of conventional antiviral clinical approaches and their mechanisms of action. Additionally, an overview of proposed and developing new molecules is provided, including nucleic-acid-based therapies and immune-mediated approaches.

Cytokines Removal During Ex-Vivo Lung Perfusion: Initial Clinical Experience.

Ex Vivo Lung Perfusion (EVLP) can be potentially used to manipulate organs and to achieve a proper reconditioning process. During EVLP pro-inflammatory cytokines have been shown to accumulate in perfusate over time and their production is correlated with poor outcomes of the graft. Aim of the present study is to investigate the feasibility and safety of cytokine adsorption during EVLP. From July 2011 to March 2020, 54 EVLP procedures have been carried out, 21 grafts treated with an adsorption system and 33 without. Comparing the grafts perfused during EVLP with or without cytokine adsorption, the use of a filter significantly decreased the levels of IL10 and GCSFat the end of the procedure. Among the 38 transplanted patients, the adsorption group experienced a significant decreased IL6, IL10, MCP1 and GCSF concentrations and deltas compared to the no-adsorption group, with a lower in-hospital mortality (p = 0.03) and 1-year death rate (p = 0.01). This interventional study is the first human experience suggesting the safety and efficacy of a porous polymer beads adsorption device in reducing the level of inflammatory mediators during EVLP. Clinical impact of cytokines reduction during EVLP must be evaluated in further studies.

Measure of lung dielectric proprieties in patients with Idiopathic Pulmonary Fibrosis: correlation with clinical, radiological and pulmonary functional parameters.

BACKGROUND: Dielectric properties of biological tissues are biophysical parameters; in lung they change with amount of air, blood and parenchyma. Remote Dielectric Sensing (ReDS™) technology measures dielectric properties of lung tissues quantifying the content of fluids inside the scan volume. We aimed to evaluate the reliability of ReDS™ measure in Idiopathic Pulmonary Fibrosis (IPF) patients and in healthy volunteers, and to investigate the correlation of ReDS™ score with clinical, radiological and functional parameters. METHODS: We conducted a prospective observational study, including 52 patients with diagnosis of IPF and 17 healthy volunteers; for each patient we recorded: complete functional evaluation, dyspnoea score (mMRC scale), Usual Interstitial Pneumonia (UIP) Computed Tomography (CT) pattern (UIP definite or probable) and ReDS™ measure (expressed in %). RESULTS: ReDS™ measure was reported as correct both in patients and controls, the firsts with higher scores (33.8% vs 29.1%, p = 0.003). In IPF patients we observed a significant inverse correlation with ReDS™ score and Forced Vital Capacity (FVC), Vital Capacity (VC) and Total Lung Capacity (TLC) measures and, when we considered only patients with UIP definite CT pattern, the correlation was inverse with FVC, VC, TLC, DLCO. In IPF patients the higher was mMRC dyspnoea index, the higher was ReDS™ score. No significant correlations were observed between ReDS™ score and functional parameters in healthy controls. DISCUSSION: We demonstrated a correlation of ReDS™ scores with some functional (mainly indicative or diagnostic for restriction) and clinical parameters in IPF patients; the score was correlated with density of tissues possibly quantifying tissue fibrosis in IPF patients.

Idiopathic Pulmonary Fibrosis and Post-COVID-19 Lung Fibrosis: Links and Risks.

Idiopathic pulmonary fibrosis (IPF) is considered the paradigmatic example of chronic progressive fibrosing disease; IPF does not result from a primary immunopathogenic mechanism, but immune cells play a complex role in orchestrating the fibrosing response. These cells are activated by pathogen-associated or danger-associated molecular patterns generating pro-fibrotic pathways or downregulating anti-fibrotic agents. Post-COVID pulmonary fibrosis (PCPF) is an emerging clinical entity, following SARS-CoV-2 infection; it shares many clinical, pathological, and immune features with IPF. Similarities between IPF and PCPF can be found in intra- and extracellular physiopathological pro-fibrotic processes, genetic signatures, as well as in the response to antifibrotic treatments. Moreover, SARS-CoV-2 infection can be a cause of acute exacerbation of IPF (AE-IPF), which can negatively impact on IPF patients' prognosis. In this narrative review, we explore the pathophysiological aspects of IPF, with particular attention given to the intracellular signaling involved in the generation of fibrosis in IPF and during the SARS-CoV-2 infection, and the similarities between IPF and PCPF. Finally, we focus on COVID-19 and IPF in clinical practice.

Interventional pulmonology techniques in lung transplantation.

Lung transplantation is a key therapeutic option for several end-stage lung diseases. Interventional pulmonology techniques, mostly bronchoscopy, play a key role throughout the whole path of lung transplantation, from donor evaluation to diagnosis and management of post-transplant complications. We carried out a non-systematic, narrative literature review aimed at describing the main indications, contraindications, performance characteristics and safety profile of interventional pulmonology techniques in the context of lung transplantation. We highlighted the role of bronchoscopy during donor evaluation and described the debated role of surveillance bronchoscopy (with bronchoalveolar lavage and transbronchial biopsy) to detect early rejection, infections and airways complications. The conventional (transbronchial forceps biopsy) and the new techniques (i.e. cryobiopsy, biopsy molecular assessment, probe-based confocal laser endomicroscopy) can detect and grade rejection. Several endoscopic techniques (e.g. balloon dilations, stent placement, ablative techniques) are employed in the management of airways complications (ischemia and necrosis, dehiscence, stenosis and malacia). First line pleural interventions (i.e. thoracentesis, chest tube insertion, indwelling pleural catheters) may be useful in the context of early and late pleural complications occurring after lung transplantation. High quality studies are advocated to define endoscopic standard protocols and thus help improving long-term prognostic outcomes of lung transplant recipients.

Gender differences in obesity hypoventilation syndrome.

Sleep-disordered breathing (SDB) is a group of sleep-related breathing disorders which includes obstructive sleep apnea (OSA), central sleep apnea (CSA), and obesity hypoventilation syndrome (OHS). OHS is characterized by a combination of obesity, daytime hypercapnia and hypoxemia, and sleep-disordered breathing without other known hypoventilation causes, such as severe obstructive or restrictive parenchymal lung disease, kyphoscoliosis, severe hypothyroidism, neuromuscular disease, or congenital central hypoventilation syndrome. Four hundred ninety potentially eligible references were identified; of these, 462 abstracts or full texts were excluded because they did not fulfil inclusion criteria. We reviewed the full text of the remaining 38 papers which fulfilled the inclusion criteria. The role of gender in SDB and particularly in OHS is not well known. In general, the diseases are under-recognized in women and only a few studies have reported the impact of gender on clinical presentation and treatment outcome. On the other hand, there is often a delay in diagnosing these diseases in women as compared to men; therefore, they are often more advanced when diagnosed in women. Better understanding and clinical awareness of the higher OHS prevalence in postmenopausal women may lead to earlier diagnosis and a more timely and appropriate treatment. Further studies are needed to assess the prevalence of OHS in women, the effect of menopause on OHS, and the increased risk of OHS, which will hopefully lead to optimizing OHS patient care.

One-year mortality in COVID-19 is associated with patients' comorbidities rather than pneumonia severity.

BACKGROUND: In patients with pneumonia or acute respiratory distress syndrome who survived hospitalization, one-year mortality can affect up to one third of discharged patients. Therefore, significant long-term mortality after COVID-19 respiratory failure could be expected. The primary outcome of the present study was one-year all-cause mortality in hospitalized COVID-19 patients. METHODS: Observational study of COVID-19 patients hospitalized at Papa Giovanni XXIII Hospital (Bergamo, Italy), during the first pandemic wave. RESULTS: A total of 1326 COVID-19 patients were hospitalized. Overall one-year mortality was 33.6% (N 446/1326), with the majority of deaths occurring during hospitalization (N=412, 92.4%). Thirty-four patients amongst the 914 discharged (3.7%) subsequentely died within one year. A third of these patients died for advanced cancer, while death without a cause other than COVID-19 was uncommon (8.8% of the overall post-discharge mortality). In-hospital late mortality (i.e. after 28 days of admission) interested a population with a lower age, and fewer comorbidities, more frequentely admitted in ICU. Independent predictors of post-discharge mortality were age over 65 years (HR 3.19; 95% CI 1.28-7.96, p-value=0.013), presence of chronic obstructive pulmonary disease (COPD) (HR 2.52; 95% CI 1.09-5.83, p-value=0.031) or proxy of cardiovascular disease (HR 4.93; 95% CI 1.45-16.75, p-value=0.010), and presence of active cancer (HR 3.64; 95% CI 1.50-8.84, p-value=0.004), but not pneumonia severity. CONCLUSIONS: One-year post-discharge mortality depends on underlying patients' comorbidities rather than COVID-19 pneumonia severity per se. Awareness among physicians of predictors of post-discharge mortality might be helpful in structuring a follow-up program for discharged patients.

Mandibular Torus as a New Index of Success for Mandibular Advancement Devices.

BACKGROUND: In obstructive sleep apnoea (OSA), treatment with mandibular advancement devices (MADs) reduces patients' Apnoea-Hypopnoea index (AHI) scores and improves their sleepiness and quality of life. MADs are non-invasive alternatives for patients who cannot tolerate traditional continuous positive airway pressure (CPAP) therapy. The variability of responses to these devices makes it necessary to search for predictors of success. The aim of our study was to evaluate the presence of mandibular torus as a predictor of MAD efficacy in OSA and to identify other potential cephalometric factors that could influence the response to treatment. METHODS: This was a retrospective cohort study. The study included 103 patients diagnosed of OSA who met the criteria for initiation of treatment with MAD. Structural variables were collected (cephalometric and the presence or absence of mandibular torus). Statistical analysis was performed to evaluate the existence of predictive factors for the efficacy of MADs. RESULTS: A total of 103 patients who were consecutively referred for treatment with MAD were included (89.3% men); the mean age of the participants was 46.3 years, and the mean AHI before MAD was 31.4 (SD 16.2) and post- MAD 11.3 (SD 9.2). Thirty-three percent of patients had mandibular torus. Torus was associated with a better response (odds ratio (OR) = 2.854 (p = 0.035)) after adjustment for sex, age, body mass index (BMI; kg/m2), the angle formed by the occlusal plane to the sella-nasion plane (OCC plane to SN), overinjection, and smoking. No cephalometric predictors of efficacy were found that were predictive of MAD treatment success. CONCLUSIONS: The presence of a mandibular torus practically triples the probability of MAD success. This is the simplest examination with the greatest benefits in terms of the efficacy of MAD treatment for OSA.

Keep on tailoring CMV management in lung transplantation: 24 versus 12-month CMV hyperimmune globulins regimen effects in combined universal prophylaxis.

BACKGROUND: In lung transplantation (LTx), Cytomegalovirus (CMV) management is based on prophylaxis or pre-emptive therapy. CMV hyperimmune globulins (CMV IG) added to prophylactic antiviral agents reduce CMV manifestations and acute rejection. The length of prophylaxis regimens is variable among studies with different results. METHODS: We conduced, after demonstrating efficacy of 12 months prophylaxis on acute rejections and CMV pneumonia, a single center retrospective study comparing, during the second year after LTx, clinical effects of a long (24 months) versus short (12 months) course of combined CMV prophylaxis scheme, based on antiviral agents and CMV IG. RESULTS: We included 120 patients, 70 received a long (24 months) and 50 a short (12 months) prophylaxis. The long prophylaxis group, at 18th month, had a lower rate of neutrophilic alveolitis in BAL (63.6% vs. 94.4%, P=0.029). No other statistically significant differences were observed among the two groups of patients although we observed a reduction in both CMV (56.4% vs. 76.0% P=n.s.) and bacterial infections (23.7% vs. 32.0%, P=n.s.) during the 18th month of follow-up. We did not observe differences among two groups in acute rejection rate on transbronchial lung biopsies. CONCLUSIONS: The combined long prophylaxis course based on antiviral agents and CMV IG provides a reduction trend in CMV or bacterial infections even if not statistically significant. The significant reduction in neutrophilia in BAL compared to the cohort undergoing prophylaxis for 12 months should be carefully interpreted. An 18-month prophylaxis could be a good suggestion to be tested by other larger prospective studies.

COPD, but Not Asthma, Is Associated with Worse Outcomes in COVID-19: Real-Life Data from Four Main Centers in Northwest Italy.

Introduction: Asthma, along with inhaled steroids, was initially considered a risk factor for worse clinical outcomes in COVID-19. This was related to the higher morbidity observed in asthma patients during previous viral outbreaks. This retrospective study aimed at evaluating the prevalence of asthma among patients admitted due to SARS-CoV-2 infection as well as the impact of inhaled therapies on their outcomes. Furthermore, a comparison between patients with asthma, COPD and the general population was made. Methods: All COVID-19 inpatients were recruited between February and July 2020 from four large hospitals in Northwest Italy. Data concerning medical history, the Charlson Comorbidity Index (CCI) and the hospital stay, including length, drugs and COVID-19 complications (respiratory failure, lung involvement, and the need for respiratory support) were collected, as well as the type of discharge. Results: patients with asthma required high-flow oxygen therapy (33.3 vs. 14.3%, p = 0.001) and invasive mechanical ventilation (17.9 vs. 9.5%, p = 0.048) more frequently when compared to the general population, but no other difference was observed. Moreover, asthma patients were generally younger than patients with COPD (59.2 vs. 76.8 years, p < 0.001), they showed both a lower mortality rate (15.4 vs. 39.4%, p < 0.001) and a lower CCI (3.4 vs. 6.2, p < 0.001). Patients with asthma in regular therapy with ICS at home had significantly shorter hospital stay compared to those with no treatments (25.2 vs. 11.3 days, p = 0.024). Discussion: Our study showed that asthma is not associated with worse outcomes of COVID-19, despite the higher need for respiratory support compared with the general population, while the use of ICS allowed for a shorter hospital stay. In addition, the comparison of asthma with COPD patients confirmed the greater frailty of the latter, according to their multiple comorbidities.

Validation of a Simple, Rapid, and Cost-Effective Method for Acute Rejection Monitoring in Lung Transplant Recipients.

Despite advances in immunosuppression therapy, acute rejection remains the leading cause of graft dysfunction in lung transplant recipients. Donor-derived cell-free DNA is increasingly being considered as a valuable biomarker of acute rejection in several solid organ transplants. We present a technically improved molecular method based on digital PCR that targets the mismatch between the recipient and donor at the HLA-DRB1 locus. Blood samples collected sequentially post-transplantation from a cohort of lung recipients were used to obtain proof-of-principle for the validity of the assay, correlating results with transbronchial biopsies and lung capacity tests. The results revealed an increase in dd-cfDNA during the first 2 weeks after transplantation related to ischemia-reperfusion injury (6.36 ± 5.36%, p < 0.0001). In the absence of complications, donor DNA levels stabilized, while increasing again during acute rejection episodes (7.81 ± 12.7%, p < 0.0001). Respiratory tract infections were also involved in the release of dd-cfDNA (9.14 ± 15.59%, p = 0.0004), with a positive correlation with C-reactive protein levels. Overall, the dd-cfDNA percentages were inversely correlated with the lung function values measured by spirometry. These results confirm the value of dd-cfDNA determination during post-transplant follow-up to monitor acute rejection in lung recipients, achieved using a rapid and inexpensive approach based on the HLA mismatch between donor and recipient.