Linking CT and SPECT based analysis for quantitative follow-up of vascular perfusion defects in COVID-19

COVID-19 still affects a large population worldwide with possible post-traumatic sequelae requiring long-term patient follow-up for the most severe cases. The lung is the primary target of severe acute respiratory syndrome coronavirus 2 (SARS- CoV-2) infection. In particular, the virus affects the entire pulmonary vascular tree from large vessels to capillaries probably leading to an abnormal vascular remodeling. In this study we investigated two modalities for assessing this remodeling, SPECT perfusion scintigraphy and computed tomography, the latter enabling the computation of vascular remodeling patterns. We analyzed on a cohort of 30 patients the relationship between vascular remodeling and perfusion defects in the peripheral lung area, which is a predominant focus of the COVID-19 infectious patterns. We found that such relationship exists, demonstrated by moderate significant correlations between SPECT and CT measures. In addition, a vascular remodeling index derived from the z-score normalized peripheral CT images showed a moderate significant correlation with the diffusing capacity of the lung for carbon monoxide (DLCO) measures. Altogether these results point CT scan as a good tool for a standardized, quantitative, and easy-to-use routine characterization and follow-up of COVID-19-induced vascular remodeling. An extensive validation of these results will be carried out in the near future on a larger cohort. © 2023 SPIE.

Current status and prospect of global development of lung transplantation

During the novel coronavirus pneumonia (COVID-19) pandemic from 2020 to 2021, lung transplantation entered a new stage of development worldwide. Globally, more than 70 000 cases of lung transplantation have been reported to the International Society for Heart and Lung Transplantation (ISHLT). With the development of medical techniques over time, the characteristics of lung transplant donors and recipients and the indications of pediatric lung transplantation recipients have undergone significant changes. Application of lung transplantation in the treatment of COVID-19-related acute respiratory distress syndrome (ARDS) has also captivated worldwide attention. Along with persistent development of lung transplantation, it will be integrated with more novel techniques to make breakthroughs in the fields of artificial lung and xenotransplantation. In this article, research progresses on the characteristics of lung transplant donors and recipients around the world were reviewed and the development trend was predicted, enabling patients with end-stage lung disease to obtain more benefits from the development of lung transplantation technique.Copyright © 2022 Organ Transplantation. All rights reserved.

Development and prospect of clinical research on lung transplantation in post-COVID-19 era

Lung transplantation has been advanced for nearly half a century around the globe, and it has been developed rapidly for over 20 years in China. The field of lung transplantation in China has been gradually integrated into the international community. The outbreak of novel coronavirus pneumonia (COVID-19) in 2020 brought big challenges, as well as diverted the worldwide attention to the development of lung transplantation in China, accelerating international communication and cooperation. With the steadily deepening of clinical and basic research on lung transplantation for severe cases of COVID-19, organ transplant physicians have deepened the understanding and thinking of the maintenance of donors, selection of elderly and pediatric candidates, and perioperative management of recipients, as the future perspective of lung transplantation in China. For interdisciplinary research related to lung transplantation, it is necessary to carry out multi-center clinical trials with qualified study design and constantly promote the theoretic and practical innovation.Copyright © 2021 The authors.

Modulation of pulmonary blood flow in patients with acute respiratory failure.

BACKGROUND: Impairment of ventilation and perfusion (V/Q) matching is a common mechanism leading to hypoxemia in patients with acute respiratory failure requiring intensive care unit (ICU) admission. While ventilation has been thoroughly investigated, little progress has been made to monitor pulmonary perfusion at the bedside and treat impaired blood distribution. The study aimed to assess real-time changes in regional pulmonary perfusion in response to a therapeutic intervention. METHODS: Single-center prospective study that enrolled adult patients with ARDS caused by SARS-Cov-2 who were sedated, paralyzed, and mechanically ventilated. The distribution of pulmonary perfusion was assessed through electrical impedance tomography (EIT) after the injection of a 10-ml bolus of hypertonic saline. The therapeutic intervention consisted in the administration of inhaled nitric oxide (iNO), as rescue therapy for refractory hypoxemia. Each patient underwent two 15-min steps at 0 and 20 ppm iNO, respectively. At each step, respiratory, gas exchange, and hemodynamic parameters were recorded, and V/Q distribution was measured, with unchanged ventilatory settings. RESULTS: Ten 65 [56-75] years old patients with moderate (40%) and severe (60%) ARDS were studied 10 [4-20] days after intubation. Gas exchange improved at 20 ppm iNO (PaO2/FiO2 from 86 ± 16 to 110 ± 30 mmHg, p = 0.001; venous admixture from 51 ± 8 to 45 ± 7%, p = 0.0045; dead space from 29 ± 8 to 25 ± 6%, p = 0.008). The respiratory system's elastic properties and ventilation distribution were unaltered by iNO. Hemodynamics did not change after gas initiation (cardiac output 7.6 ± 1.9 vs. 7.7 ± 1.9 L/min, p = 0.66). The EIT pixel perfusion maps showed a variety of patterns of changes in pulmonary blood flow, whose increase positively correlated with PaO2/FiO2 increase (R2 = 0.50, p = 0.049). CONCLUSIONS: The assessment of lung perfusion is feasible at the bedside and blood distribution can be modulated with effects that are visualized in vivo. These findings might lay the foundations for testing new therapies aimed at optimizing the regional perfusion in the lungs.

Post-acute prevalence of occult pulmonary embolism after hospitalisation for Covid-19

Background: During hospitalization for Covid-19 the prevalence of pulmonary embolism (PE) is ~15%. Occult PE may be undiagnosed during hospitalization. Also, after discharge, factors such as residual (local) inflammation and relative physical inactivity may predispose to PE. Aim(s): To study the presence of occult PE and pulmonary perfusion defects three months after discharge from hospitalization for Covid-19. Method(s): In this prospective study we performed CT pulmonary angiography (CTPA) in adults three months after discharge from hospitalization for moderate-to-critical Covid-19. Exclusion criteria: therapeutic anticoagulation, diagnosed PE during hospitalization, CTPA contra-indications. Primary outcome measure was presence of PE. Secondary outcomes were wedge shaped perfusion defects on subtraction iodine maps, D-dimer concentration, presence of Years criteria at follow-up, and pulmonary parenchymal abnormalities. Result(s): 26 patients (65% male, 61 (SD10) y, hospital length of stay 11 (IQR9-15) days, 34% ICU treatment) underwent CTPA at 13 (SD2) weeks after discharge. 25 patients (96%) had no evidence for PE while one post-ICU patient demonstrated a suspected partial occlusion of a subsegmental pulmonary artery. No wedge shaped perfusion defects were found. D-Dimer values were <1000 ng/ml in all patients and none had Years criteria. Extent of parenchymal abnormalities decreased compared to acute phase (CT severity score 7 (SD5) vs 13 (SD5), p=0.004). Conclusion(s): Prevalence of occult PE three months after discharge from hospitalization for Covid-19 was negligible in our sample. CTPA should not be routinely performed in these patients. .

X-Ray Analysis of Donor Lungs within an Ex Vivo Lung Perfusion System (EVLP): A Pilot Study for the Assessment of the Brixia Score to Predict Transplantability

Background: Ex vivo lung perfusion (EVLP) is a safe and effective technique for lung evaluation and reconditioning of marginal donor lungs (DLs). The assessment of the DLs during EVLP is crucial for the transplantability decision making. There are a limited number of studies regarding the radiographic analysis of EVLP lungs. Furthermore, there are only few Xray grading scores available. The Brixia score is a proven radiological score for the severity grading of lung abnormalities with confirmed predictive power of the clinical outcome that was successfully used in pneumonia patients during the COVID-19 pandemic. It was the aim of our study to evaluate the X-ray findings of DLs within EVLP and investigate the prognostic potential of this score regarding transplantability and clinical outcome. Method(s): This is a retrospective observational pilot study. Between 2016 and 2022, a total of 277 double-lung transplantations (DLTx) were performed in our department. X-Rays of the last ten consecutive EVLP-DLs were blindly evaluated regarding the severity of interstitial and alveolar infiltrates and the Brixia score was calculated. Furthermore, the results (transplantability, severe primary graft dysfunction PGD, survival, hospital stay) and EVLP parameters (delta pO2) of these EVLP-DLs cases were analyzed and compared with the Brixia score for each case. Result(s): A range of Brixia score values from min 4 to max 18 was determined. Seven DLs were transplanted (mean delta pO 391 mm Hg, mean Brixia score 6.7) while three were rejected (mean delta pO 211 mm Hg, mean Brixia score 6). The two EVLP-DLs cases with the higher Brixia score (mean 15) were transplanted after EVLP. Postoperative PGD Grade 3 at 48 hours was recorded in one case without correlation to the Brixia score (Brixia score 4). All patients survived hospital discharge with a mean ICU and hospital stay of 9 and 30 days, respectively. Conclusion(s): In our pilot study, the Brixia score did not predict transplantability or postoperative function during EVLP. Additional studies are needed to further evaluate the use and clinical prognostic power of radiologic assessment with this or other scores in the EVLP lung assessment.

Longitudinal lung function assessment of patients hospitalised with COVID-19 using 1H and 129Xe lung MRI

Introduction: The progression of pathophysiological pulmonary changes in patients following acute COVID-19 is not well established. Method(s): Patients hospitalised with COVID-19 pneumonia without signs of ILD, had MRI exams at a median of 6 (n=9), 12 (n=9), 25 (n=7), and 52 (n=3) weeks. MRI sequences included: dynamic contrast enhanced (DCE) lung perfusion,129 Xe diffusion weighted (DW-MRI), 129Xe ventilation and 129Xe 3D dissolved phase imaging. Result(s): 9 patients (age 56+/-9 years;7 male;1 required treatment in an ICU) were recruited. Median RBC:TP was abnormally low at all visits compared to reference age and sex matched data. An individual's RBC:TP was significantly and positively associated with an increase in their pulmonary blood volume (p=0.026). For patients with 52 week data available, one showed a continued increase in RBC:TP, 2 patients maintained a low RBC:TP (Figure 1). Ventilation defect percentage, and ventilation heterogeneity significantly decreased at 25 weeks compared to 6 129 129 129 weeks (p=0.010 and p=0.048). DW-MRI was normal at all visits. Dissolved phase xenon imaging showed RBC:TP significantly increased at 12 and 25 weeks compared to 6 weeks (p=0.048). Conclusion(s): In patients recovering after COVID-19, poor gas transfer is reflected by impaired xenon transfer, which improves alongside pulmonary blood volume.

Quantitative Assessment of Lung Volumes and Enhancement in Patients with COVID-19: Role of Dual-Energy CT.

Dual-energy computed tomography (DECT) has been used for detecting pulmonary embolism, but the role of lung perfusion DECT as a predictor of prognosis of coronavirus disease 2019 (COVID-19) has not been defined yet. The aim of our study was to explore whether the enhancement pattern in COVID-19+ patients relates to the disease outcome. A secondary aim was to compare the lung volumes in two subgroups of patients. In this observational study, we considered all consecutive COVID-19+ patients who presented to the emergency room between January 2021 and December 2021 with respiratory symptoms (with mild to absent lung consolidation) and were studied by chest contrast-enhanced DECT to be eligible. Two experienced radiologists post-processed the images using the "lung-analysis" software (SyngoVia). Absolute and relative enhancement lung volumes were assessed. Patients were stratified in two subgroups depending on clinical outcome at 30 days: (i) good outcome (i.e., discharge, absence of clinical or imaging signs of disease); (ii) bad outcome (i.e., hospitalization, death). Patient sub-groups were compared using chi-square test or Fisher test for qualitative parameters, chi-square test or Spearman's Rho test for quantitative parameters, Students' t-test for parametric variables and Wilcoxon test for non-parametric variables. We enrolled 78 patients (45M), of whom, 16.7% had good outcomes. We did not observe any significant differences between the two groups, both in terms of the total enhancement evaluation (p = 0.679) and of the relative enhancement (p = 0.918). In contrast, the average lung volume of good outcome patients (mean value of 4262 mL) was significantly larger than that of bad outcome patients (mean value of 3577.8 mL), p = 0.0116. All COVID-19+ patients, with either good or bad outcomes, presented similar enhancement parameters and relative enhancements, underlining no differences in lung perfusion. Conversely, a significant drop in lung volume was identified in the bad outcome subgroup eligible compared to the good outcome subgroup.

Lung perfusion assessment in Long-COVID children: a pilot study

Aim/Introduction: There is growing interest in the clinical management of children with persisting and debilitating symptoms after Sars-COV-2 infection (Long-COVID). Chronic effects could arise from residual clot burden and small vessel inflammation, both expressing endothelial damage that may lead to lung perfusion impairment. 99mTc-macroaggregated albumin (MAA) SPECT/ CT is a well-established tool to detect lung perfusion defects, even at the small-vessels level. This pilot study aimed at assessing lung perfusion in Long-COVID children with MAA SPECT/CT and at comparing functional patterns with clinical scenarios during acute infection and follow-up. Material(s) and Method(s): Clinical and biochemical data were collected during acute infection and follow-up in 10 children (6 males and 4 females, mean age: 13.6 years) fulfilling Long-COVID diagnostic criteria and complaining of chronic fatigue and post-exertional malaise after mild efforts. All patients underwent a cardiopulmonary test and MAA SPECT/CT scan. Dose activities were properly chosen according to the EANM guidelines for lung scintigraphy in children. Intravenous injections were administered to patients in the supine position immediately before the planar scan, which was followed by the lung SPECT/CT acquisition. Reconstructed studies were visually analyzed. Imaging results were compared with clinical scenarios during acute infection and follow-up. Result(s): The severity of acute disease was mild and moderate in 6/10 (60 %) and 2/10 (20 %) children, respectively;there were no significant symptoms in the remaining 2 cases. Persisting symptoms after the acute phase were observed in 7/10 (70%) patients. Five out of 10 (50.0%) children showed perfusion defects on MAA SPECT/CT scan, without morphological alterations on co-registered CT. In particular, 4/5 (80%) children with lung perfusion abnormalities were previously affected by a mild acute infection, whereas a single child (20%) was asymptomatic. However, during the follow-up, persisting symptoms (e.g., headache and dyspnea after the cardiopulmonary test) were detected in 5/5 (100%) patients. Conversely, among the five children without lung perfusion defects, only 2 (40%) showed persisting symptoms (in particular, headache), while 3 (60%) children had dyspnea after the cardiopulmonary test. Conclusion(s): This pilot study showed lung perfusion defects in Long-COVID children. Despite the small patient sample, perfusion abnormalities on MAA SPECT/CT seem to occur more frequently in children with persisting symptoms following the acute infection and dyspnea after the cardiopulmonary test. Larger cohort studies are needed to confirm these preliminary results, providing a better selection among children who can benefit the most from MAA SPECT/CT imaging.

Lung Ventilation and Perfusion SPECT in long-COVID-19

Aim/Introduction: Knowledge about COVID-19's physiopathology is still scarce, mainly with respect to the recovery phase. Nonetheless, its association with an increased incidence of thromboembolic phenomena is well established. Ventilation/Perfusion single-photon emission computed tomography (VP-SPECT) plays a major role in the evaluation of pulmonary embolism (PE) and microvascular disease, given its high sensibility and low radiation burden. We aim, with this study, to review the contribution of VP-SPECT in these patients' follow-up, with a particular focus on those with long-COVID-19. Material(s) and Method(s): We performed a retrospective study with COVID-19 patients that underwent VP-SPECT in our Department, until march-2022. Functional impairment of global pulmonary perfusion (FIGPP) was quantified by assigning points for each segment with a mismatch defect (a total of 36 points in 18 segments). PE was defined by the presence of segmental or subsegmental pleural-based mismatch defect(s) assessed at least 2 points. All relevant demographic/clinical data were collected. Result(s): Sixty patients (mean age 54.8+/-12.8 years, 51.3% female) with a history of COVID-19 underwent VP-SPECT on average 285.6+/-127.2 days after infection. There was a high prevalence of severe infections (58%, N=29) and admitted patients (64.9%, N=37), with a mean length of stay in the hospital of 22.5+/-17.2 days. Six patients (10.2%) had acute PE associated. The main reason for VPSPECT was post-infection fatigue/dyspnoea (71.7%;N=43). Only 6.9% of patients underwent VP-SPECT during acute disease (N=4). Median FIGPP was 6% (0-47). Patients who were hospitalized (p=0.066) or who had severe disease (p=0.161) showed no statistically significant differences in FIGPP. Management change after VP-SPECT occurred in 11.9% (N=7). Patients who did not start anticoagulant therapy (N=46) showed a median FIGPP of 6% (0-18). Conclusion(s): Our findings suggest that, although clinically relevant, persistent post-COVID-19 fatigue/dyspnoea symptoms do not appear to be justified by a FIGPP associated with significant thromboembolism and are unrelated to disease severity and need for hospitalisation. However, VP-SPECT played an important role both in excluding serious sequelae of thromboembolism and in identifying patients at higher risk of developing pulmonary hypertension.

Lung VQ scan in COVID-19: Various patterns of perfusion defects

Aim/Introduction: While COVID-19 infection is associated with the increased risk of pulmonary thromboembolism (PTE), it may also affects the lungs that causes ventilation-perfusion (VQ) patterns other than PTE. Although extensive research has been done to address different anatomical patterns of COVID-19, there is a knowledge gap in terms of VQ lung scintigraphy in these patients. The purpose of this study is to demonstrate these patterns and to show how important it is to use SPECT/CT in addition to planar images to differ these patterns from PTE [1, 2, 3]. Material(s) and Method(s): We collected lung scans performed in 64 patients with history of past/recent COVID-19 infection (in the preceding 1.5 years) who were referred for VQ scintigraphy. The scan was performed using Q-SPECT/Q-planar (26.6%), Q-SPECT/CT (42.2%), VQ-SPECT (14%) and VQ-SPECT/CT (17.2%). Interpretation was based on the EANM criteria. Result(s): Of these patients 10 (15.6%) had positive scan for PTE. Moreover, in 49 (76.6%) of these patients, anatomical abnormalities were observed compatible with COVID-19 infection. The patterns seen were as follows: 1) apparent hot spot due to focal sparing of lung, 2) zones of decreased and increased perfusion, 3) zones of normal and increased perfusion, 4) small sub-segmental defects matching with CT findings, and 5) reverse mismatched defects. Also, a case of loculated pleural effusion in CT with Q abnormalities was observed. Conclusion(s): Lung perfusion abnormalities are common findings in COVID-19 patients. They are usually either due to pulmonary embolism, parenchymal infiltrates, or other causes of mosaic attenuation related to, but not specific of the pathophysiology of COVID-19 infection. The value of VQ SPECT/CT imaging to detect and differentiate the various types of Q abnormalities was noticeable.

Lung perfusion assessment in Long-COVID children: a pilot study

Aim/Introduction: There is growing interest in the clinical management of children with persisting and debilitating symptoms after Sars-COV-2 infection (Long-COVID). Chronic effects could arise from residual clot burden and small vessel inflammation, both expressing endothelial damage that may lead to lung perfusion impairment. 99mTc-macroaggregated albumin (MAA) SPECT/ CT is a well-established tool to detect lung perfusion defects, even at the small-vessels level. This pilot study aimed at assessing lung perfusion in Long-COVID children with MAA SPECT/CT and at comparing functional patterns with clinical scenarios during acute infection and follow-up. Material(s) and Method(s): Clinical and biochemical data were collected during acute infection and follow-up in 10 children (6 males and 4 females, mean age: 13.6 years) fulfilling Long-COVID diagnostic criteria and complaining of chronic fatigue and post-exertional malaise after mild efforts. All patients underwent a cardiopulmonary test and MAA SPECT/CT scan. Dose activities were properly chosen according to the EANM guidelines for lung scintigraphy in children. Intravenous injections were administered to patients in the supine position immediately before the planar scan, which was followed by the lung SPECT/CT acquisition. Reconstructed studies were visually analyzed. Imaging results were compared with clinical scenarios during acute infection and follow-up. Result(s): The severity of acute disease was mild and moderate in 6/10 (60 %) and 2/10 (20 %) children, respectively;there were no significant symptoms in the remaining 2 cases. Persisting symptoms after the acute phase were observed in 7/10 (70%) patients. Five out of 10 (50.0%) children showed perfusion defects on MAA SPECT/CT scan, without morphological alterations on co-registered CT. In particular, 4/5 (80%) children with lung perfusion abnormalities were previously affected by a mild acute infection, whereas a single child (20%) was asymptomatic. However, during the follow-up, persisting symptoms (e.g., headache and dyspnea after the cardiopulmonary test) were detected in 5/5 (100%) patients. Conversely, among the five children without lung perfusion defects, only 2 (40%) showed persisting symptoms (in particular, headache), while 3 (60%) children had dyspnea after the cardiopulmonary test. Conclusion(s): This pilot study showed lung perfusion defects in Long-COVID children. Despite the small patient sample, perfusion abnormalities on MAA SPECT/CT seem to occur more frequently in children with persisting symptoms following the acute infection and dyspnea after the cardiopulmonary test. Larger cohort studies are needed to confirm these preliminary results, providing a better selection among children who can benefit the most from MAA SPECT/CT imaging.

Lung VQ scan in COVID-19: Various patterns of perfusion defects

Aim/Introduction: While COVID-19 infection is associated with the increased risk of pulmonary thromboembolism (PTE), it may also affects the lungs that causes ventilation-perfusion (VQ) patterns other than PTE. Although extensive research has been done to address different anatomical patterns of COVID-19, there is a knowledge gap in terms of VQ lung scintigraphy in these patients. The purpose of this study is to demonstrate these patterns and to show how important it is to use SPECT/CT in addition to planar images to differ these patterns from PTE [1, 2, 3]. Material(s) and Method(s): We collected lung scans performed in 64 patients with history of past/recent COVID-19 infection (in the preceding 1.5 years) who were referred for VQ scintigraphy. The scan was performed using Q-SPECT/Q-planar (26.6%), Q-SPECT/CT (42.2%), VQ-SPECT (14%) and VQ-SPECT/CT (17.2%). Interpretation was based on the EANM criteria. Result(s): Of these patients 10 (15.6%) had positive scan for PTE. Moreover, in 49 (76.6%) of these patients, anatomical abnormalities were observed compatible with COVID-19 infection. The patterns seen were as follows: 1) apparent hot spot due to focal sparing of lung, 2) zones of decreased and increased perfusion, 3) zones of normal and increased perfusion, 4) small sub-segmental defects matching with CT findings, and 5) reverse mismatched defects. Also, a case of loculated pleural effusion in CT with Q abnormalities was observed. Conclusion(s): Lung perfusion abnormalities are common findings in COVID-19 patients. They are usually either due to pulmonary embolism, parenchymal infiltrates, or other causes of mosaic attenuation related to, but not specific of the pathophysiology of COVID-19 infection. The value of VQ SPECT/CT imaging to detect and differentiate the various types of Q abnormalities was noticeable.

Scintigraphic Patterns In Planar Pulmonary Perfusion-Only Studies In Patients With Dyspnea and Clinical Suspicion of COVID-19 Infection

Aim/Introduction: The purpose of this study is to perform a descriptive analysis of the scintigraphic patterns in pulmonary perfusion studies in patients with COVID-19 clinical suspicion, and its relation with biological (PCR positiviy) and biochemical parameters (D dimer plasmatic levels (DD)) as well as the presence of comorbidities. Material(s) and Method(s): 84 patients (44 male: 52.4% and 40 female: 47.6%, mean age: 68.08+/-15.85), either outpatients or hospitalized, with clinical COVID-19 suspicion, with conduction of the study from the onset of symptoms to even 19 months after it, in case of clinical persistence, and their pulmonary perfusion studies have been analyzed by three nuclear medicine physicians. The different patterns observed have been categorized in homogeneous, heterogeneous and segmental, and independence test have been run, by means of Chi square test (X2) or Fisher's exact test (FET), to detect a possible association of the latter with laboratory confirmation of COVID-19 infection, DD plasmatic levels (normal: <500ng/ml, high: 500-1.000ng/ ml, and very high:>1.000ng/ml) and the absence or presence of comorbidity (pulmonary disease, cardiovascular disease or both).Odds Ratio (OR) calculation has been run to estimate the probability of presenting a heterogeneous scintigraphic pattern in COVID infected vs. not infected patients, as well as in patients with very high vs. high DD levels. Result(s): Different scintigraphic patterns (31% homogeneous, 58.3% heterogeneous or 10,7% segmental) have been observed in patients with suspected COVID-19, of whom 65.5% were confirmed cases. Independence tests showed association between scintigraphic perfusion patterns and COVID-19 confirmation [X2= 8.0, p<0.05, Phi=0,324], while it did not in relation to DD levels [FET= 2.74, p>0.05]. The relative risk of presenting a heterogeneous scintigraphy in COVID+ patients is 0.16 ([0.043-0.595] %95 CI), thus infection can be considered a mild protector factor for heterogeneity. With regard to absence of previous disease (27.4%) or presence of pulmonary (4.8%), cardiac (57.1%) or coexistence of both diseases (10.7%), no significant association to the scintigraphic pattern could be found (chi2= 7.511, p>0.05]). Conclusion(s): Different scintigraphic patterns in pulmonary perfusion studies have been observed in patients with COVID-19 suspicion, being the heterogeneous one remarkably more frequent. It is significantly associated to positive microbiological test results but not to plasmatic DD levels or presence of comorbidity. Covid-infected patients have lower probability of presenting a heterogeneous scintigraphy pattern than not infected ones.

Utility of dual-energy computed tomography in the association of COVID-19 pneumonia severity.

Aim: Coronavirus disease 2019 pneumonia differs from ordinary pneumonia in that it is associated with lesions that reduce pulmonary perfusion. Dual-energy computed tomography is well suited to elucidate the etiology of coronavirus disease 2019 pneumonia, because it highlights changes in organ blood flow. In this study, we investigated whether dual-energy computed tomography could be used to determine the severity of coronavirus disease 2019 pneumonia. Methods: Patients who were diagnosed with coronavirus disease 2019 pneumonia, admitted to our hospital, and underwent dual-energy computed tomography were included in this study. Dual-energy computed tomography findings, plane computed tomography findings, disease severity, laboratory data, and clinical features were compared between two groups: a critical group (18 patients) and a non-critical group (30 patients). Results: The dual-energy computed tomography results indicated that the percentage of flow loss was significantly higher in the critical group compared with the non-critical group (P < 0.001). Additionally, our data demonstrated that thrombotic risk was associated with differences in clinical characteristics (P = 0.018). Receiver operating characteristic analysis revealed that the percentage of flow loss, evaluated using dual-energy computed tomography, could predict severity in the critical group with 100% sensitivity and 77% specificity. However, there were no significant differences in the receiver operating characteristic values for dual-energy computed tomography and plane computed tomography. Conclusion: Dual-energy computed tomography can be used to associate the severity of coronavirus disease 2019 pneumonia with high accuracy. Further studies are needed to draw definitive conclusions.

Nebivolol: an effective option against long-lasting dyspnoea following COVID-19 pneumonia - a pivotal double-blind, cross-over controlled study.

Background: Pulmonary microvascular occlusions can aggravate SARS-CoV-2 pneumonia and result in a variable decrease in capillary blood volume (Vc). Dyspnoea may persist for several weeks after hospital discharge in many patients who have "radiologically recovered" from COVID-19 pneumonia. Dyspnoea is frequently "unexplained" in these cases because abnormalities in lung vasculature are understudied. Furthermore, even when they are identified, therapeutic options are still lacking in clinical practice, with nitric oxide (NO) supplementation being used only for severe respiratory failure in the hospital setting. Nebivolol is the only selective ß1 adrenoceptor antagonist capable of inducing nitric oxide-mediated vasodilation by stimulating endothelial NO synthase via ß3 agonism. The purpose of this study was to compare the effect of nebivolol versus placebo in patients who had low Vc and complained of dyspnoea for several weeks after COVID-19 pneumonia. Methods: Patients of both genders, aged ≥18 years, non-smokers, who had a CT scan that revealed no COVID-related parenchymal lesions but still complaining of dyspnoea 12-16 weeks after hospital discharge, were recruited. Spirometrical volumes, blood haemoglobin, SpO2, simultaneous diffusing capacity for carbon monoxide (CO) and NO (DLCO and DLNO, respectively), DLNO/DLCO ratio, Vc and exhaled NO (eNO) were measured together with their dyspnoea score (DS), heart frequency (HF), and blood arterial pressure (BAP). Data were collected before and one week after both placebo (P) and nebivolol (N) (2.5 mg od) double-blind cross-over administered at a two-week interval. Data were statistically compared, and p<0.05 assumed as statistically significant. Results: Eight patients (3 males) were investigated. In baseline, their mean DS was 2.5±0.6 SD, despite the normality of lung volumes. DLCO and DLNO mean values were lower than predicted, while mean DLNO/DLCO ratio was higher. Mean Vc proved substantially reduced. Placebo did not modify any variable (all p=ns) while N improved DLco and Vc significantly (+8.5%, p<0.04 and +17.7%, p<0.003, respectively). eNO also was significantly increased (+17.6%, p<0.002). Only N lowered the dyspnoea score (-76%, p<0.001). Systolic and diastolic BAP were slightly lowered (-7.5%, p<0.02 and -5.1%, p<0.04, respectively), together with HF (-16.8%, p<0.03). Conclusions: The simultaneous assessment of DLNO, DLCO, DLNO/DLCO ratio, and Vc confirmed that long-lasting dyspnoea is related to hidden abnormalities in the lung capillary vasculature. These abnormalities can persist even after the complete resolution of parenchymal lesions regardless of the normality of lung volumes. Nebivolol, but not placebo, improves DS and Vc significantly. The mechanism suggested is the NO-mediated vasodilation via the ß3 adrenoceptor stimulation of endothelial NO synthase. This hypothesis is supported by the substantial increase of eNO only assessed after nebivolol. As the nebivolol tolerability in these post-COVID normotensive patients was very good, the therapeutic use of nebivolol against residual and symptomatic signs of long-COVID can be suggested in out-patients.

Xenogeneic support for the recovery of human donor organs.

VIDEO ABSTRACT.

COMPARATIVE EFFECTIVENESS OF INHALED NITRIC OXIDE IN ARDS AND VIRAL PNEUMONIA WITH AND WITHOUT COVID-19

SESSION TITLE: ECMO and ARDS in COVID-19 Infections SESSION TYPE: Rapid Fire Original Inv PRESENTED ON: 10/17/2022 12:15 pm - 1:15 pm PURPOSE: Inhaled nitric oxide (iNO) is a potent vasodilator of pulmonary vasculature improving perfusion to ventilated alveoli in ARDS and other lung pathologies. During the pandemic, intensivists turned to iNO as “salvage” therapy in COVID-19 patients. Rationale was driven by vasodilatory effect and antiviral properties despite lack of evidence of clear benefit even in patients without COVID. We hypothesized that iNO would provide reduced increases in pulmonary perfusion and subsequent gas exchange improvement in COVID-19 patients due to extensive endothelial damage and coagulopathy throughout the pulmonary vasculature. METHODS: Our IRB exempt analysis examined patients hospitalized with and without COVID-19 from January 2020 to September 2021 who received at least 24h of invasive mechanical ventilation with iNO (15-20ppm). Effectiveness outcomes were PaO2/FIO2 ratio(PFR), PEEP/CPAP level, and PaCO2 serially measured and observed up to 24 hours prior to initiation of iNO and for up to 120h post iNO administration. Data were statistically controlled for age, sex, race, time to initiation of therapy and COVID-19 directed treatment. RESULTS: From January 2020 and September 2021, 42 patients were admitted to the ICU and received invasive mechanical ventilation and iNO. Results are sequenced as ARDS COVID-negative, ARDS COVID-positive, viral pneumonia COVID-negative, viral-pneumonia COVID-positive. Patient n = 8/14/6/14. Median age was 56/55/63/62 years. Demographics split 64-62% male vs 36-38% female in ARDS without/with COVID, 50%/83% male vs 50%/17% female in viral pneumonia without/with COVID. Racial distribution resulted 75%/93%/86%/83% White vs 25%/0%/17%/14% Black. Other races constituted less than 7% of patient total in any category. PFR delta from -24h to +120h post-iNO = +35/+35/+41/+22. PEEP/CPAP delta from -24h to +120h = -4/-1/-3/-2. PaCO2 delta mmHg from -24h to +120h = -21/-23/-9/-13. Median Hospital LOS = 26/26.5/17/19 days. Median ICU LOS = 15.8/19.0/13.8/17.6 days. Hospital mortality = 100% across all 4 subgroups. CONCLUSIONS: ARDS patients with or without COVID showed similar rates of PFR response to iNO, however viral pneumonia patients with COVID exhibited a blunted PFR response vs those without COVID. No statistically significant difference was observed with respect to PEEP/CPAP levels, PaCO2 mmHg, hospital or ICU LOS, or mortality. CLINICAL IMPLICATIONS: Our findings suggest that the presence of COVID-19 did not significantly inhibit response to iNO in ARDS or other viral pneumonia patients. Further evaluation of other indirect markers of gas exchange could provide further evidence of responsiveness. DISCLOSURES: No relevant relationships by Katherine Burns No relevant relationships by Karen Hamad No relevant relationships by Bobby Malik No relevant relationships by Richard Walo Jr No relevant relationships by Wilhelmine Wiese-Rometsch No relevant relationships by Stephanie Williams