Ultrastructural characterization of alveolar microvascular damage in severe COVID-19 respiratory failure.

Endothelial dysfunction is a key phenomenon in COVID-19, induced by direct viral endothelial infection and secondary inflammation, mainly affecting the microvascular circulation. However, few studies described the subcellular aspects of the lung microvasculature and the associated thrombotic phenomena, which are widely present in severe COVID-19 cases. To that end, in this transversal observational study we performed transmission and scanning electron microscopy in nine lung samples of patients who died due to COVID-19, obtained via minimally invasive autopsies in Sao Paulo, Brazil, in 2020. All patients died due to acute respiratory failure and had microvascular thrombosis at histology. Electron microscopy revealed areas of endothelial damage with basal lamina disruption and virus infection in endothelial cells. In the capillary lumens, the ultrastructure of the thrombi is depicted, with red blood cells stacking, dysmorphism and hemolysis, fibrin meshworks, and extracellular traps. Our description illustrates the complex pathophysiology of microvascular thrombosis at the cellular level, which leads to some of the peculiar characteristics of severe COVID-19.NEW & NOTEWORTHY In this study, electron microscopy was used to explain the pathophysiology of respiratory failure in severe COVID-19. Before the advent of vaccination, as the virus entered the respiratory system, it rapidly progressed to the alveolar capillary network and, before causing exudative alveolar edema, it caused mainly thrombosis of the pulmonary microcirculation with preserved lung compliance explaining "happy hypoxia." Timing of anticoagulation is of pivotal importance in this disease.

Effectiveness of therapeutic heparin versus prophylactic heparin on death, mechanical ventilation, or intensive care unit admission in moderately ill patients with covid-19 admitted to hospital: RAPID randomised clinical trial.

OBJECTIVE: To evaluate the effects of therapeutic heparin compared with prophylactic heparin among moderately ill patients with covid-19 admitted to hospital wards. DESIGN: Randomised controlled, adaptive, open label clinical trial. SETTING: 28 hospitals in Brazil, Canada, Ireland, Saudi Arabia, United Arab Emirates, and US. PARTICIPANTS: 465 adults admitted to hospital wards with covid-19 and increased D-dimer levels were recruited between 29 May 2020 and 12 April 2021 and were randomly assigned to therapeutic dose heparin (n=228) or prophylactic dose heparin (n=237). INTERVENTIONS: Therapeutic dose or prophylactic dose heparin (low molecular weight or unfractionated heparin), to be continued until hospital discharge, day 28, or death. MAIN OUTCOME MEASURES: The primary outcome was a composite of death, invasive mechanical ventilation, non-invasive mechanical ventilation, or admission to an intensive care unit, assessed up to 28 days. The secondary outcomes included all cause death, the composite of all cause death or any mechanical ventilation, and venous thromboembolism. Safety outcomes included major bleeding. Outcomes were blindly adjudicated. RESULTS: The mean age of participants was 60 years; 264 (56.8%) were men and the mean body mass index was 30.3 kg/m2. At 28 days, the primary composite outcome had occurred in 37/228 patients (16.2%) assigned to therapeutic heparin and 52/237 (21.9%) assigned to prophylactic heparin (odds ratio 0.69, 95% confidence interval 0.43 to 1.10; P=0.12). Deaths occurred in four patients (1.8%) assigned to therapeutic heparin and 18 patients (7.6%) assigned to prophylactic heparin (0.22, 0.07 to 0.65; P=0.006). The composite of all cause death or any mechanical ventilation occurred in 23 patients (10.1%) assigned to therapeutic heparin and 38 (16.0%) assigned to prophylactic heparin (0.59, 0.34 to 1.02; P=0.06). Venous thromboembolism occurred in two patients (0.9%) assigned to therapeutic heparin and six (2.5%) assigned to prophylactic heparin (0.34, 0.07 to 1.71; P=0.19). Major bleeding occurred in two patients (0.9%) assigned to therapeutic heparin and four (1.7%) assigned to prophylactic heparin (0.52, 0.09 to 2.85; P=0.69). CONCLUSIONS: In moderately ill patients with covid-19 and increased D-dimer levels admitted to hospital wards, therapeutic heparin was not significantly associated with a reduction in the primary outcome but the odds of death at 28 days was decreased. The risk of major bleeding appeared low in this trial. TRIAL REGISTRATION: ClinicalTrials.gov NCT04362085.

Heparin for Moderately Ill Patients with Covid-19.

BACKGROUND: Heparin, in addition to its anticoagulant properties, has anti-inflammatory and potential anti-viral effects, and may improve endothelial function in patients with Covid-19. Early initiation of therapeutic heparin could decrease the thrombo-inflammatory process, and reduce the risk of critical illness or death. METHODS: We randomly assigned moderately ill hospitalized ward patients admitted for Covid-19 with elevated D-dimer level to therapeutic or prophylactic heparin. The primary outcome was a composite of death, invasive mechanical ventilation, non-invasive mechanical ventilation or ICU admission. Safety outcomes included major bleeding. Analysis was by intention-to-treat. RESULTS: At 28 days, the primary composite outcome occurred in 37 of 228 patients (16.2%) assigned to therapeutic heparin, and 52 of 237 patients (21.9%) assigned to prophylactic heparin (odds ratio, 0.69; 95% confidence interval [CI], 0.43 to 1.10; p=0.12). Four patients (1.8%) assigned to therapeutic heparin died compared with 18 patients (7.6%) assigned to prophylactic heparin (odds ratio, 0.22; 95%-CI, 0.07 to 0.65). The composite of all-cause mortality or any mechanical ventilation occurred in 23 (10.1%) in the therapeutic heparin group and 38 (16.0%) in the prophylactic heparin group (odds ratio, 0.59; 95%-CI, 0.34 to 1.02). Major bleeding occurred in 2 patients (0.9%) with therapeutic heparin and 4 patients (1.7%) with prophylactic heparin (odds ratio, 0.52; 95%-CI, 0.09 to 2.85). CONCLUSIONS: In moderately ill ward patients with Covid-19 and elevated D-dimer level, therapeutic heparin did not significantly reduce the primary outcome but decreased the odds of death at 28 days. Trial registration numbers: NCT04362085 ; NCT04444700.

Expression patterns of peroxiredoxin genes in bronchial epithelial cells exposed to diesel exhaust particles.

Several mechanisms have been suggested to explain the adverse effects of air pollutants on airway cells. One such explanation is the presence of high concentrations of oxidants and pro-oxidants in environmental pollutants. All animal and plant cells have developed several mechanisms to prevent damage by oxidative molecules. Among these, the peroxiredoxins (PRDXs) are of interest due to a high reactivity with reactive oxygen species (ROS) through the functioning of the thioredoxin/thioredoxin reductase system. This study aimed to verify the gene expression patterns of the PRDX family in bronchial epithelial airway cells (BEAS-2B) cells exposed to diesel exhaust particles (DEPs) at a concentration of 15 µg/mL for 1 or 2 h because this it is a major component of particulate matter in the atmosphere. There was a significant decrease in mRNA fold changes of PRDX2 (0.43 ± 0.34; *p = 0.0220), PRDX5 (0.43 ± 0.34; *p = 0.0220), and PRDX6 (0.33 ± 0.25; *p = 0.0069) after 1 h of exposure to DEPs. The reduction in mRNA levels may consequently lead to a decrease in the levels of PRDX proteins, increasing oxidative stress in bronchial epithelial cells BEAS-2B and thus, negatively affecting cellular functions.

Randomized trials of therapeutic heparin for COVID-19: A meta-analysis.

BACKGROUND: Pulmonary endothelial injury and microcirculatory thromboses likely contribute to hypoxemic respiratory failure, the most common cause of death, in patients with COVID-19. Randomized controlled trials (RCTs) suggest differences in the effect of therapeutic heparin between moderately and severely ill patients with COVID-19. We did a systematic review and meta-analysis of RCTs to determine the effects of therapeutic heparin in hospitalized patients with COVID-19. METHODS: We searched PubMed, Embase, Web of Science, medRxiv, and medical conference proceedings for RCTs comparing therapeutic heparin with usual care, excluding trials that used oral anticoagulation or intermediate doses of heparin in the experimental arm. Mantel-Haenszel fixed-effect meta-analysis was used to combine odds ratios (ORs). RESULTS AND CONCLUSIONS: There were 3 RCTs that compared therapeutic heparin to lower doses of heparin in 2854 moderately ill ward patients, and 3 RCTs in 1191 severely ill patients receiving critical care. In moderately ill patients, there was a nonsignificant reduction in all-cause death (OR, 0.76; 95% CI, 0.57-1.02), but significant reductions in the composite of death or invasive mechanical ventilation (OR, 0.77; 95% CI, 0.60 0.98), and death or any thrombotic event (OR, 0.58; 95% CI, 0.45-0.77). Organ support-free days alive (OR, 1.29; 95% CI, 1.07-1.57) were significantly increased with therapeutic heparin. There was a nonsignificant increase in major bleeding. In severely ill patients, there was no evidence for benefit of therapeutic heparin, with significant treatment-by-subgroup interactions with illness severity for all-cause death (P = .034). In conclusion, therapeutic heparin is beneficial in moderately ill patients but not in severely ill patients hospitalized with COVID-19.

Heparin Therapy Improving Hypoxia in COVID-19 Patients - A Case Series.

INTRODUCTION: Elevated D-dimer is a predictor of severity and mortality in COVID-19 patients, and heparin use during in-hospital stay has been associated with decreased mortality. COVID-19 patient autopsies have revealed thrombi in the microvasculature, suggesting that hypercoagulability is a prominent feature of organ failure in these patients. Interestingly, in COVID-19, pulmonary compliance is preserved despite severe hypoxemia corroborating the hypothesis that perfusion mismatch may play a significant role in the development of respiratory failure. METHODS: We describe a series of 27 consecutive COVID-19 patients admitted to Sirio-Libanes Hospital in São Paulo-Brazil and treated with heparin in therapeutic doses tailored to clinical severity. RESULTS: PaO2/FiO2 ratio increased significantly over the 72 h following the start of anticoagulation, from 254(±90) to 325(±80), p = 0.013, and 92% of the patients were discharged home within a median time of 11 days. There were no bleeding complications or fatal events. DISCUSSION: Even though this uncontrolled case series does not offer absolute proof that micro thrombosis in the pulmonary circulation is the underlying mechanism of respiratory failure in COVID-19, patient's positive response to heparinization contributes to the understanding of the pathophysiological mechanism of the disease and provides valuable information for the treatment of these patients while we await the results of further prospective controlled studies.

Heparin therapy improving hypoxia in COVID-19 patients - a case series [preprint]

INTRODUCTION: Elevated D-dimer is predictor of severity and mortality in COVID-19 patients and heparin use during in hospital stay has been associated to decreased mortality. COVID-19 patient autopsies have revealed thrombi in the microvasculature, suggesting intravascular coagulation as a prominent feature of organ failure in these patients. Interestingly, in COVID19, pulmonary compliance is preserved despite severe hypoxemia corroborating the hypothesis that perfusion mismatch may play a significant role in the development of respiratory failure. METHODS: We describe a series of 27 consecutive COVID-19 patients admitted to the Pulmonology service at Sirio-Libanes Hospital in São Paulo-Brazil treated with heparin in therapeutic doses tailored to clinical severity. RESULTS: PaO2/FiO2 ratio increased significantly over the 72 hours following the start of anticoagulation, from 254(±90) to 325(±80), p=0.013, and over half of the patients were discharged home within an average time of 7.3 (±4.0) days. Half of mechanically ventilated patients were extubated within 10.3 (±1.5) days. The remaining patients showed progressive improvement and there were no bleeding complications or fatal events. DISCUSSION: Even though this uncontrolled case series does not offer absolute proof of DIC as the underlying mechanism of respiratory failure in COVID-19, as well as patients positive response to tailored dose heparinization, it contributes to the understanding of the physiopathological mechanism of the disease and provides valuable information for the treatment of these very sick patients while we await the results of further prospective controlled studies

Prognostic factors of recurrence of malignant pleural effusion: what is the role of neoplasia progression?

BACKGROUND: It is known that malignant pleural effusion (MPE) recurs rapidly, in a considerable number of patients. However, some patients do not have MPE recurrence. Since MPE is associated with an average survival of 4-7 months, accurate prediction of prognosis may help recognize patients at higher risk of pleural recurrence, aiming to individualize more intensive treatment strategies. METHODS: A prospectively assembled database of cases with pleural effusion treated at a single institution analyzed a subset of patients with symptomatic MPE. Prognostic factors for pleural recurrence were identified by univariable analysis using Kaplan-Meier method and the log-rank test was used for the comparison between the curves. Univariate and multiple Cox regression models were used to evaluate the risk (HR) of recurrence. Receiver operating characteristics (ROC) analysis determined the cutoff points for continuous variables. RESULTS: A total of 288 patients were included in the analysis. Recurrence-free survival was of 76.6% at 6 months and 73.3% at 12 months. Univariable analysis regarding factors affecting postoperative recurrence was: lymphocytes, platelets, pleural procedure, chemotherapy lines and number of metastases. The independent factors for recurrence-free survival were pleural procedure and chemotherapy lines. Patients who were submitted to pleurodesis had a protective factor for recurrence, with an HR =0.34 (95% CI, 0.15-0.74, P=0.007). On the other hand, patients submitted to the 1st and 2nd line of palliative CT had, respectively, an HR risk = 2.81 (95% CI, 1.10-7.28, P=0.034) and HR =3.23 (95% CI, 1.33-7.84, P=0.010). CONCLUSIONS: patients receiving the first or second line of systemic treatment have a higher risk of MPE recurrence when compared to patients who underwent MPE treatment before starting the systemic treatment. The definitive treatment of MPE, such as pleurodesis, was associated with a lower risk of MPE recurrence.

Wet M1a non-small cell lung cancer: is it possible to predict recurrence of pleural effusion?

BACKGROUND: The propose was to recognize risk factors of malignant pleural effusion (MPE) recurrence in patients with symptomatic M1a non-small cell lung cancer (NSCLC). METHODS: All patients with NSCLC and MPE submitted to pleural palliative procedures were enrolled in a prospective study. Group I contained patients who had pleural recurrence, and Group II with no pleural recurrence. Prognostic factors for pleural recurrence were identified by univariable analysis, using Fisher's exact test for categorical variables and Student's t test for quantitative variables. Afterwards the significant variables were entered into a multivariable logistic regression analysis (with P<0.05 considered significant). Receiver operating characteristics (ROC) analysis determined the cutoff points for continuous variables. RESULTS: A total of 82 patients were included in the analysis. There were 15 patients (18.3%) in Group I and 67 patients (81.7%) in Group II. Univariable analysis regarding factors affecting postoperative recurrence was: adenosine deaminase concentration in pleural fluid <16 mg/dL (P=0.04), albumin concentration in pleural fluid <2.4 mg/dL (P=0.03), administration of second-line palliative chemotherapy (P=0.018) and type of procedure [therapeutic pleural aspiration (TPA)] (P=0.023). At the multivariable analysis, only the type of procedure (TPA) (P=0.031) was identified as independent predictor of recurrence. CONCLUSIONS: The identification of this factor may assist the choice of the optimal palliative technique; at the first episode of MPE in NSCLC patients and definitive procedure as pleurodesis or indwelling pleural catheter are recommended.

Lung Perfusion and Ventilation During Cardiopulmonary Bypass Reduces Early Structural Damage to Pulmonary Parenchyma.

BACKGROUND: It is unclear whether maintaining pulmonary perfusion and ventilation during cardiopulmonary bypass (CPB) reduces pulmonary inflammatory tissue injury compared with standard CPB where the lungs are not ventilated and are minimally perfused. In this study, we tested the hypothesis that maintenance of lung perfusion and ventilation during CPB decreases regional lung inflammation, which may result in less pulmonary structural damage. METHODS: Twenty-seven pigs were randomly allocated into a control group only submitted to sternotomy (n = 8), a standard CPB group (n = 9), or a lung perfusion group (n = 10), in which lung perfusion and ventilation were maintained during CPB. Hemodynamics, gas exchanges, respiratory mechanics, and systemic interleukins (ILs) were determined at baseline (T0), at the end of 90 minutes of CPB (T90), and 180 minutes after CPB (T180). Bronchoalveolar lavage (BAL) ILs were obtained at T0 and T180. Dorsal and ventral left lung tissue samples were examined for optical and electron microscopy. RESULTS: At T90, there was a transient reduction in PaO2/FIO2 in CPB (126 ± 64 mm Hg) compared with the control and lung perfusion groups (296 ± 46 and 244 ± 57 mm Hg; P < 0.001), returning to baseline at T180. Serum ILs were not different among the groups throughout the study, whereas there were significant increases in BAL IL-6 (P < 0.001), IL-8 (P < 0.001), and IL-10 (P < 0.001) in both CPB and lung perfusion groups compared with the control group. Polymorphonuclear counts within the lung tissue were smaller in the lung perfusion group than in the CPB group (P = 0.006). Electron microscopy demonstrated extrusion of surfactant vesicles into the alveolar spaces and thickening of the alveolar septa in the CPB group, whereas alveolar and capillary histoarchitecture was better preserved in the lung perfusion group. CONCLUSIONS: Maintenance of lung perfusion and ventilation during CPB attenuated early histologic signs of pulmonary inflammation and injury compared with standard CPB. Although increased compared with control animals, there were no differences in serum or BAL IL in animals receiving lung ventilation and perfusion during CPB compared with standard CPB.

Human bronchial epithelial cells exposed in vitro to diesel exhaust particles exhibit alterations in cell rheology and cytotoxicity associated with decrease in antioxidant defenses and imbalance in pro- and anti-apoptotic gene expression.

Diesel exhaust particles (DEPs) from diesel engines produce adverse alterations in cells of the airways by activating intracellular signaling pathways and apoptotic gene overexpression, and also by influencing metabolism and cytoskeleton changes. This study used human bronchial epithelium cells (BEAS-2B) in culture and evaluates their exposure to DEPs (15ug/mL for 1 and 2 h) in order to determine changes to cell rheology (viscoelasticity) and gene expression of the enzymes involved in oxidative stress, apoptosis, and cytotoxicity. BEAS-2B cells exposed to DEPs were found to have a significant loss in stiffness, membrane stability, and mitochondrial activity. The genes involved in apoptosis [B cell lymphoma 2 (BCL-2 and caspase-3)] presented inversely proportional expressions (p = 0.05, p = 0.01, respectively), low expression of the genes involved in antioxidant responses [SOD1 (superoxide dismutase 1); SOD2 (superoxide dismutase 2), and GPx (glutathione peroxidase) (p = 0.01)], along with an increase in cytochrome P450, family 1, subfamily A, polypeptide 1 (CYP1A1) (p = 0.01). These results suggest that alterations in cell rheology and cytotoxicity could be associated with oxidative stress and imbalance between pro- and anti-apoptotic genes.

Impact of Cardiopulmonary Bypass on Respiratory Mucociliary Function in an Experimental Porcine Model.

BACKGROUND: The impact of cardiac surgery using cardiopulmonary bypass (CPB) on the respiratory mucociliary function is unknown. This study evaluated the effects of CPB and interruption of mechanical ventilation on the respiratory mucociliary system. METHODS: Twenty-two pigs were randomly assigned to the control (n = 10) or CPB group (n = 12). After the induction of anesthesia, a tracheostomy was performed, and tracheal tissue samples were excised (T0) from both groups. All animals underwent thoracotomy. In the CPB group, an aorto-bicaval CPB was installed and maintained for 90 minutes. During the CPB, mechanical ventilation was interrupted, and the tracheal tube was disconnected. A second tracheal tissue sample was obtained 180 minutes after the tracheostomy (T180). Mucus samples were collected from the trachea using a bronchoscope at T0, T90 and T180. Ciliary beat frequency (CBF) and in situ mucociliary transport (MCT) were studied in ex vivo tracheal epithelium. Mucus viscosity (MV) was assessed using a cone-plate viscometer. Qualitative tracheal histological analysis was performed at T180 tissue samples. RESULTS: CBF decreased in the CPB group (13.1 ± 1.9 Hz vs. 11.1 ± 2.1 Hz, p < 0.05) but not in the control group (13.1 ± 1 Hz vs. 13 ± 2.9 Hz). At T90, viscosity was increased in the CPB group compared to the control (p < 0.05). No significant differences were observed in in situ MCT. Tracheal histology in the CPB group showed areas of ciliated epithelium loss, submucosal edema and infiltration of inflammatory cells. CONCLUSION: CPB acutely contributed to alterations in tracheal mucocilliary function.

Myocardial protection induced by fentanyl in pigs exposed to high-dose adrenaline.

The use of high doses of adrenaline is common in critical patients, especially during cardiac arrest. During these situations, myocardial dysfunction can be a result of multiple factors, including adrenaline use. In addition, opioids have been shown to have anti-arrhythmic and anti-ischemic mechanisms that may confer cardiac protection. This study aimed to evaluate the effects of fentanyl on myocardial function in pigs exposed to high-dose adrenaline. After institutional ethics committee approval, 26 pigs were randomly allocated to receive either 20 µg/kg fentanyl (n = 10; fentanyl group) administered 5 min before five doses of adrenaline (20 µg/kg), equivalent-volume saline (n = 10; saline group) using the same adrenaline dosing protocol, or neither fentanyl nor adrenaline (n = 6; sham group). The fentanyl group showed lower levels of troponin at the end of the sixth hour compared with the saline group (1.91 ± 1.47 vs 5.44 ± 5.35 ng/mL, P = 0.019). Transmission electron microscopy and immunohistochemistry also showed less myocardial injury in the fentanyl group. The conclusion was reached that fentanyl attenuates myocardial injury caused by high-dose adrenaline without blunting the hemodynamic effect of adrenaline.

Diesel exhaust particulates affect cell signaling, mucin profiles, and apoptosis in trachea explants of Balb/C mice.

Particulate matter from diesel exhaust (DEP) has toxic properties and can activate intracellular signaling pathways and induce metabolic changes. This study was conducted to evaluate the activation of extracellular signal-regulated kinase (ERK) and c-Jun N-terminal kinase (JNK) and to analyze the mucin profile (acid (AB(+) ), neutral (PAS(+) ), or mixed (AB/PAS(+) ) mucus) and vacuolization (V) of tracheal explants after treatment with 50 or 100 µg/mL DEP for 30 or 60 min. Western blot analyses showed small increases in ERK1/2 and JNK phosphorylation after 30 min of 100 µg/mL DEP treatment compared with the control. An increase in JNK phosphorylation was observed after 60 min of treatment with 50 µg/mL DEP compared with the control. We did not observe any change in the level of ERK1/2 phosphorylation after treatment with 50 µg/mL DEP. Other groups of tracheas were subjected to histological sectioning and stained with periodic acid-Schiff (PAS) reagent and Alcian Blue (AB). The stained tissue sections were then subjected to morphometric analysis. The results obtained were compared using ANOVA. Treatment with 50 µg/mL DEP for 30 min or 60 min showed a significant increase (p < 0.001) in the amount of acid mucus, a reduction in neutral mucus, a significant reduction in mixed mucus, and greater vacuolization. Our results suggest that compounds found in DEPs are able to activate acid mucus production and enhance vacuolization and cell signaling pathways, which can lead to airway diseases.

Pentraxin 3 accelerates lung injury in high tidal volume ventilation in mice.

Mechanical ventilation is the major cause of iatrogenic lung damage in intensive care units. Although inflammation is known to be involved in ventilator-induced lung injury (VILI), several aspects of this process are still unknown. Pentraxin 3 (PTX3) is an acute phase protein with important regulatory functions in inflammation which has been found elevated in patients with acute respiratory distress syndrome. This study aimed at investigating the direct effect of PTX3 production in the pathogenesis of VILI. Genetically modified mice deficient and that over express murine Ptx3 gene were subjected to high tidal volume ventilation (V(T)=45 mL/kg, PEEP(zero)). Morphological changes and time required for 50% increase in respiratory system elastance were evaluated. Gene expression profile in the lungs was also investigated in earlier times in Ptx3-overexpressing mice. Ptx3 knockout and wild-type mice developed same lung injury degree in similar times (156±42 min and 148±41 min, respectively; p=0.8173). However, Ptx3 over-expression led to a faster development of VILI in Ptx3-overexpressing mice (77±29 min vs 118±41 min, p=0.0225) which also displayed a faster kinetics of Il1b expression and elevated Ptx3, Cxcl1 and Ccl2 transcripts levels in comparison with wild-type mice assessed by quantitative real-time polymerase chain reaction. Ptx3 deficiency did not impacted the time for VILI induced by high tidal volume ventilation but Ptx3-overexpression increased inflammatory response and reflected in a faster VILI development.

Avaliação dos níveis de citocinas e da função pulmonar de pacientes submetidos à cirurgia cardíaca com circulação extracorpórea / Evaluation of cytokine levels and pulmonary function in patients undergoing coronary artery bypass graft / Evaluación de los niveles de citocinas y de la función pulmonar de pacientes sometidos a la cirugía cardíaca con circulación extracorpórea

JUSTIFICATIVA E OBJETIVOS: A Síndrome da Resposta Inflamatória Sistêmica é uma ocorrência habitual em cirurgias cardíacas com circulação extracorpórea (CEC). O objetivo deste estudo foi avaliar os níveis sistêmicos e pulmonares de citocinas e a correlação com a função pulmonar em pacientes submetidos à revascularização miocárdica (RM) com CEC. MÉTODOS: O estudo foi aprovado pela Comissão de Ética institucional, com a avaliação de 13 pacientes submetidos à RM com CEC. Após a indução anestésica, ao término da CEC, realizaram-se dosagens plasmáticas e no lavado broncoalveolar de IL-1β, IL-6, IL-8, IL-10 e TNF-α. Foram avaliados o tempo de CEC e de cirurgia, a relação PaO2/FiO2, o gradiente alvéolo-arterial de oxigênio (GA-aO2), o shunt e a complacência pulmonares. Os resultados foram submetidos à análise de variância para medidas repetidas (*p < 0,05) e coeficiente de correlação de Spearman. RESULTADOS: Observaram-se aumento dos níveis de citocinas no plasma e no lavado broncoalveolar após a CEC e relação direta entre o aumento da IL-1β e a diminuição da complacência pulmonar (p = 0,0439), assim como relação inversa entre o aumento da IL-10 e a redução da complacência (p = 0,0325). O aumento da IL-6 teve relação direta com o tempo de CEC (p = 0,012), enquanto o aumento da IL-8 teve relação direta com o tempo de cirurgia (p < 0,0001). Os níveis de IL-1β, IL-8 e TNF-α foram maiores no LBA em relação ao plasma. CONCLUSÕES: Ocorre aumento dos níveis de citocinas no plasma e lavado broncoalveolar após a CEC e há correlação entre o aumento dos níveis de citocinas e o tempo de CEC e de cirurgia e as alterações na complacência pulmonar.

BACKGROUND AND OBJECTIVES: Systemic inflammatory response syndrome is commonly observed in coronary artery bypass grafts (CABG) with cardiopulmonary bypass (CB). The objective of this study was to evaluate the systemic and pulmonary levels of cytokines and their correlation with lung function in patients undergoing myocardial revascularization (MR) with CB. METHODS: This study was approved by the Institutional Ethics Committee, and 13 patients undergoing MR with CB were evaluated. After anesthetic induction and at the end of CB, plasma and bronchoalveolar lavage levels of IL-1β, IL-6, IL-8, IL-10, and TNF-α were determined. The dur ation of CB and surgery, PaO2/FiO2 ratio, alveolar-arterial oxygen gradient (A-a gradient), shunt, and lung compliance were evaluated. Results were submitted to analysis of variance for repeated measurements (*p < 0.05) and Spearman's correlation coefficient. RESULTS: We observed increased levels of cytokines in plasma and bronchoalveolar lavage after CB and a direct relationship between the increase in IL-1β and decrease in lung compliance (p = 0.0439), as well as the inverse relationship between the increase in IL-10 and a decrease in compliance (p = 0.0325). The increase in IL-6 was directly related to the duration of CB (p = 0.012), while the increase in IL-8 was directly related to the duration of surgery (p < 0.0001). Levels of interleukin-1β, IL-8, and TNF-α in bronchoalveolar lavage were higher than in plasma. CONCLUSIONS: There is an increase in cytokine levels in plasma and bronchoalveolar lavage after CB, as well as a correlation between increased cytokine levels and CB duration and surgery and changes in lung compliance.

JUSTIFICATIVA Y OBJETIVOS: El Síndrome de la Respuesta Inflamatoria Sistémica es algo habitual en las cirugías cardíacas con circulación extracorpórea (CEC). El objetivo de este estudio fue evaluar los niveles sistémicos y pulmonares de citocinas y la correlación con la función pulmonar en los pacientes sometidos a la revascularización miocárdica (RM) con CEC. MÉTODOS: El estudio fue aprobado por la Comisión de Ética Institucional, con la evaluación de 13 pacientes sometidos a la RM con CEC. Después de la inducción anestésica al término de la CEC, se realizaron dosificaciones plasmáticas y también en el lavado broncoalveolar de IL-1β, IL-6, IL-8, IL-10 y TNF-α. Se evaluaron el tiempo de CEC y de cirugía, la relación PaO2/FiO2, el gradiente alvéolo-arterial de oxígeno (GA-aO2), el shunt y la complacencia pulmonares. Los resultados fueron sometidos al análisis de variancia para medidas repetidas (*p < 0,05) y al coeficiente de correlación de Spearman. RESULTADOS: Se observó un aumento en los niveles de citocinas en el plasma y en el lavado broncoalveolar después de la CEC y una relación directa entre el aumento de la IL-1β y la disminución de la complacencia pulmonar (p = 0,0439), como también una relación inversa entre el aumento de la IL-10 y la reducción de la complacencia (p = 0,0325). El aumento de la IL-6 tuvo una relación directa con el tiempo de CEC (p = 0,012), mientras que el aumento de la IL-8 tuvo una relación directa con el tiempo de cirugía (p < 0,0001). Los niveles de IL-1β, IL-8 y TNF-α fueron mayores en el LBA con relación al plasma. CONCLUSIONES: Ocurre un aumento de los niveles de citocinas en el plasma y en el lavado broncoalveolar después de la CEC, con una correlación entre el aumento de los niveles de citocinas y el tiempo de CEC y de cirugía, y las alteraciones en la complacencia pulmonar.

[Evaluation of cytokine levels and pulmonary function in patients undergoing coronary artery bypass graft]. / Evaluación de los niveles de citocinas y de la funciónpulmonar de pacientes sometidos a la cirugía cardíaca concirculación extracorpórea.

BACKGROUND AND OBJECTIVES: Systemic inflammatory response syndrome is commonly observed in coronary artery bypass grafts (CABG) with cardiopulmonary bypass (CB). The objective of this study was to evaluate the systemic and pulmonary levels of cytokines and their correlation with lung function in patients undergoing myocardial revascularization (MR) with CB. METHODS: This study was approved by the Institutional Ethics Committee, and 13 patients undergoing MR with CB were evaluated. After anesthetic induction and at the end of CB, plasma and bronchoalveolar lavage levels of IL-1ß, IL-6, IL-8, IL-10, and TNF-α were determined. The duration of CB and surgery, PaO(2)/FiO(2) ratio, alveolar-arterial oxygen gradient (A-a gradient), shunt, and lung compliance were evaluated. Results were submitted to analysis of variance for repeated measurements (*p < 0.05) and Spearman's correlation coefficient. RESULTS: We observed increased levels of cytokines in plasma and bronchoalveolar lavage after CB and a direct relationship between the increase in IL-1ß and decrease in lung compliance (p = 0.0439), as well as the inverse relationship between the increase in IL-10 and a decrease in compliance (p = 0.0325). The increase in IL-6 was directly related to the duration of CB (p = 0.012), while the increase in IL-8 was directly related to the duration of surgery (p < 0.0001). Levels of interleukin-1ß, IL-8, and TNF-α in bronchoalveolar lavage were higher than in plasma. CONCLUSIONS: There is an increase in cytokine levels in plasma and bronchoalveolar lavage after CB, as well as a correlation between increased cytokine levels and CB duration and surgery and changes in lung compliance.

Cholinergic hyperresponsiveness of peripheral lung parenchyma in chronic obstructive pulmonary disease.

BACKGROUND: Up to 60% of chronic obstructive pulmonary disease (COPD) patients can present airway hyperresponsiveness. However, it is not known whether the peripheral lung tissue also shows an exaggerated response to agonists in COPD. OBJECTIVES: To investigate the in vitro mechanical behavior and the structural and inflammatory changes of peripheral lung tissue in COPD patients and compare to nonsmoking controls. METHODS: We measured resistance and elastance at baseline and after acetylcholine (ACh) challenge of lung strips obtained from 10 COPD patients and 10 control subjects. We also assessed the alveolar tissue density of neutrophils, eosinophils, macrophages, mast cells and CD8+ and CD4+ cells, as well as the content of α-smooth muscle actin-positive cells and elastic and collagen fibers. We further investigated whether changes in in vitro parenchymal mechanics correlated to structural and inflammatory parameters and to in vivo pulmonary function. RESULTS: Values of resistance after ACh treatment and the percent increase in tissue resistance (%R) were higher in the COPD group (p ≤ 0.03). There was a higher density of macrophages and CD8+ cells (p < 0.05) and a lower elastic content (p = 0.003) in the COPD group. We observed a positive correlation between %R and eosinophil and CD8+ cell density (r = 0.608, p = 0.002, and r = 0.581, p = 0.001, respectively) and a negative correlation between %R and the ratio of forced expiratory volume in 1 s to forced vital capacity (r = -0.451, p < 0.05). CONCLUSIONS: The cholinergic responsiveness of parenchymal lung strips is increased in COPD patients and seems to be related to alveolar tissue eosinophilic and CD8 lymphocytic inflammation and to the degree of airway obstruction on the pulmonary function test.

Cytoskeleton and mechanotransduction in the pathophysiology of ventilator-induced lung injury.

Although mechanical ventilation is an important therapy, it can result in complications. One major complication is ventilator-induced lung injury, which is caused by alveolar hyperdistension, leading to an inflammatory process, with neutrophilic infiltration, hyaline membrane formation, fibrogenesis and impaired gas exchange. In this process, cellular mechanotransduction of the overstretching stimulus is mediated by means of the cytoskeleton and its cell-cell and cell-extracellular matrix interactions, in such a way that the mechanical stimulus of ventilation is translated into an intracellular biochemical signal, inducing endothelial activation, pulmonary vascular permeability, leukocyte chemotaxis, cytokine production and, possibly, distal organ failure. Clinical studies have shown the relationship between pulmonary distension and mortality in patients with ventilator-induced lung injury. However, although the cytoskeleton plays a fundamental role in the pathogenesis of ventilator-induced lung injury, there have been few in vivo studies of alterations in the cytoskeleton and in cytoskeleton-associated proteins during this pathological process.