Browsing by Author "Bachmann Barron, María Consuelo"

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    Acute lung injury secondary to hydrochloric acid instillation induces small airway hyperresponsiveness
    (2021) Basoalto Escobar, Roque Ignacio; Damiani Rebolledo, Luis Felipe; Bachmann Barron, María Consuelo; Fonseca, Marcelo; Barros, Marisol; Soto Muñoz, Dagoberto Igor; Araos, Joaquin; Jalil Contreras, Yorschua Frederick; Dubo, Sebastian; Retamal, Jaime; Bugedo Tarraza, Guillermo Jaime; Henriquez, Mauricio; Bruhn Cruz, Alejandro Rodrigo
    Background: Acute respiratory distress syndrome (ARDS) is a severe form of respiratory failure characterized by altered lung mechanics and poor oxygenation. Bronchial hyperresponsiveness has been reported in ARDS survivors and animal models of acute lung injury. Whether this hyperreactivity occurs at the small airways or not is unknown. Objective: To determine ex-vivo small airway reactivity in a rat model of acute lung injury (ALI) by hydrochloric acid (HCl) instillation. Methods: Twelve anesthetized rats were connected to mechanical ventilation for 4-hour, and randomly allocated to either ALI group (HCl intratracheal instillation; n=6) or Sham (intratracheal instillation of 0.9% NaCl; n=6). Oxygenation was assessed by arterial blood gases. After euthanasia, tissue samples from the right lung were harvested for histologic analysis and wet-dry weight ratio assessment. Precision cut lung slice technique (100-200 pm diameter) was applied in the left lung to evaluate ex vivo small airway constriction in response to histamine and carbachol stimulation, using phase-contrast video microscopy. Results: Rats from the ALI group exhibited hypoxemia, worse histologic lung injury, and increased lung wet-dry weight ratio as compared with the sham group. The bronchoconstrictor responsiveness was significantly higher in the ALI group, both for carbachol (maximal contraction of 84.5 +/- 2.5% versus 61.4 +/- 4.2% in the Sham group, P<0.05), and for histamine (maximal contraction of 78.6 +/- 5.3% versus 49.6 +/- 5.3% in the Sham group, P<0.05). Conclusion: In an animal model of acute lung injury secondary to HCL instillation, small airway hyperresponsiveness to carbachol and histamine is present. These results may provide further insight into the pathophysiologi of ARDS.
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    Beta-Lactam Antibiotics Can Be Measured in the Exhaled Breath Condensate in Mechanically Ventilated Patients: a Pilot Study
    (2023) Escalona Solari, José Antonio; Soto Muñoz, Dagoberto Igor; Oviedo Álvarez, Vanessa Andrea; Rivas Garrido, Elizabeth Alexis; Severino, Nicolás; Kattan Tala, Eduardo José; Andresen Hernández, Max Alfonso; Bravo Morales, Sebastián Ignacio; Basoalto Escobar, Roque Ignacio; Bachmann Barron, María Consuelo; Kwok-Yin, Wong; Pavez, Nicolás; Bruhn Cruz, Alejandro Rodrigo; Bugedo Tarraza, Guillermo Jaime; Retamal Montes, Jaime Alejandro
    Different techniques have been proposed to measure antibiotic levels within the lung parenchyma; however, their use is limited because they are invasive and associated with adverse effects. We explore whether beta-lactam antibiotics could be measured in exhaled breath condensate collected from heat and moisture exchange filters (HMEFs) and correlated with the concentration of antibiotics measured from bronchoalveolar lavage (BAL). We designed an observational study in patients undergoing mechanical ventilation, which required a BAL to confirm or discard the diagnosis of pneumonia. We measured and correlated the concentration of beta-lactam antibiotics in plasma, epithelial lining fluid (ELF), and exhaled breath condensate collected from HMEFs. We studied 12 patients, and we detected the presence of antibiotics in plasma, ELF, and HMEFs from every patient studied. The concentrations of antibiotics were very heterogeneous over the population studied. The mean antibiotic concentration was 293.5 (715) ng/mL in plasma, 12.3 (31) ng/mL in ELF, and 0.5 (0.9) ng/mL in HMEF. We found no significant correlation between the concentration of antibiotics in plasma and ELF (R2 = 0.02, p = 0.64), between plasma and HMEF (R2 = 0.02, p = 0.63), or between ELF and HMEF (R2 = 0.02, p = 0.66). We conclude that beta-lactam antibiotics can be detected and measured from the exhaled breath condensate accumulated in the HMEF from mechanically ventilated patients. However, no correlations were observed between the antibiotic concentrations in HMEF with either plasma or ELF.
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    Effect of positive end expiratory pressure on lung injury and haemodynamics during experimental acute respiratory distress syndrome treated with extracorporeal membrane oxygenation and near-apnoeic ventilation
    (2021) Araos, Joaquin; Alegría Vargas, Leyla; Garcia, Aline; Cruces, Pablo; Soto Muñoz, Dagoberto Igor; Erranz, Benjamín; Salomon, Tatiana; Medina, Tania; García Valdes, Patricio Hernán; Dubo, Sebastian; Bachmann Barron, María Consuelo; Basoalto Escobar, Roque Ignacio; Valenzuela, Emilio Daniel; Rovegno Echavarría, Maximiliano David; Vera Alarcón, María Magdalena; Retamal Montes, Jaime; Cornejo Rosas, Rodrigo Alfredo; Bugedo Tarraza, Guillermo; Bruhn, Alejandro
    Background: Lung rest has been recommended during extracorporeal membrane oxygenation (ECMO) for severe acute respiratory distress syndrome (ARDS). Whether positive end-expiratory pressure (PEEP) confers lung protection during ECMO for severe ARDS is unclear. We compared the effects of three different PEEP levels whilst applying near-apnoeic ventilation in a model of severe ARDS treated with ECMO. Methods: Acute respiratory distress syndrome was induced in anaesthetised adult male pigs by repeated saline lavage and injurious ventilation for 1.5 h. After ECMO was commenced, the pigs received standardised near-apnoeic ventilation for 24 h to maintain similar driving pressures and were randomly assigned to PEEP of 0, 10, or 20 cm H2O (n¼7 per group). Respiratory and haemodynamic data were collected throughout the study. Histological injury was assessed by a pathologist masked to PEEP allocation. Lung oedema was estimated by wet-to-dry-weight ratio. Results: All pigs developed severe ARDS. Oxygenation on ECMO improved with PEEP of 10 or 20 cm H2O, but did not in pigs allocated to PEEP of 0 cm H2O. Haemodynamic collapse refractory to norepinephrine (n¼4) and early death (n¼3) occurred after PEEP 20 cm H2O. The severity of lung injury was lowest after PEEP of 10 cm H2O in both dependent and non-dependent lung regions, compared with PEEP of 0 or 20 cm H2O. A higher wet-to-dry-weight ratio, indicating worse lung injury, was observed with PEEP of 0 cmH2O. Histological assessment suggested that lung injury was minimised with PEEP of 10 cm H2O. Conclusions: During near-apnoeic ventilation and ECMO in experimental severe ARDS, 10 cm H2O PEEP minimised lung injury and improved gas exchange without compromising haemodynamic stability.
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    Impact of Decreasing Respiratory Rate While Tolerating Moderate Hypercapnia on Lung Injury Markers in Patients with Covid-19 Related Acute Respiratory Distress Syndrome
    (2021) Damiani Rebolledo, Luis Felipe; Oviedo Álvarez, Vanessa Andrea; Alegria Aguirre, Luz Katiushka; Basoalto Escobar, Roque Ignacio; Bachmann Barron, María Consuelo; Jalil Contreras, Yorschua Frederick; Bruhn Cruz, Alejandro Rodrigo; Retamal Montes, A.; Santis Fuentes, César Antonio; Vera, M.; Bugedo Tarraza, Guillermo Jaime
    Rationale: Acute respiratory distress syndrome (ARDS) secondary to SARS-CoV-2 pneumonia is associated with a high mortality rate. Protective ventilationstrategies, by decreasing ventilator induced lung injury (VILI), have reduced mortality in patients with ARDS. However, the role of respiratory rate (RR), a centraldeterminant of the energy applied to the lung parenchyma remains uncertain. Objective: To evaluate the role of respiratory rate on systemic pro-inflammatory mediators, as markers of VILI, in patients with Covid-19-associated ARDS (CARDS) Methods: Prospective, randomized crossover trial in patients with CARDS,PaO2:FIO2 ratio less than 200 mmHg, and requiring deep sedation and neuromuscular blockade. All patients were ventilated with a tidal volume of 6 ml/kg IBW,and PEEP and FiO2 according to the ARDSNet table. If PaO2:FIO2 ratio was less than 150 mmHg, patients were positioned in the prone position.Two 12 hoursperiods with a low RR and a high RR, randomly selected, was conducted. Low RR and high RR periods were set to obtain an 8-10 breaths/min difference betweengroups while maintaining pH and PaCO2 within recommended limits. I:E ratio was held constant during the study.Hemodynamic and respiratory mechanics wereregistered, and arterial blood samples drawn for gas exchange and quantification of inflammatory biomarkers at baseline and repeated at 12 and 24 hours. Results: We enrolled 11 patients (10 males, median age 54 [51-66] years, PaO2:FIO2 108 [86-132]), and all of them were in prone position. The low RR (20 [16-23]) vs the high RR (28 [26-32]) was associated with a significantly lower energy applied to the lung (16 [12-19] vs 23 [20-32] J / min, respectively). PaCO2 and pH were kept within the recommended limits (pH 7.30 [7.25-7.35] vs 7.46 [7.43-7.50]; PaCO2 48 (45-63) vs 36 (32-38) mmHg for low and high RR, respectively).There were no significant changes in any of the respiratory mechanics parameters.The change in RR did not induce differences in any inflammatory marker (IL-6,IL-8, TNF-R1) or in the markers of epithelial (receptor for advanced glycation end products, s-RAGE; Surfactant protein D, SP-D), endothelial damage (Angiopoietin2) or the marker of profibrotic activity (transforming growth factor ß, TGF-ß) (table 1). Conclusion: These preliminary results reveal that a decrease in respiratoryrate, tolerating moderate hypercapnia, does not modify the biomarkers of lung damage compared to a strategy of high respiratory rate in patients with CARDS.
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    Physiologic Effects of High Flow Nasal Cannula Compared to Conventional Oxygen Therapy Postextubation: A Randomized Crossover Study
    (2022) Basoalto Escobar, Roque Ignacio; Damiani Rebolledo, Luis Felipe; Jalil Contreras, Yorschua Frederick; Garcia, P.; Carpio Cordero, David Bernardo; Bachmann Barron, María Consuelo; Alegria Aguirre, Luz Katiushka; Oviedo Álvarez, Vanessa Andrea; Bugedo Tarraza, Guillermo Jaime; Retamal, J.; Bruhn Cruz, Alejandro Rodrigo
    Rationale: High flow nasal cannula (HFNC) has been shown to generate several physiological which would be responsible forreducing weaning failure rates. However, there are not many physiological studies focused on the post-extubationstage.Objective: To determine the physiological effects of HFNC in the post-extubation period.Methods:Prospective randomizedcrossover study in the post-extubation period of patients with acute respiratory failure (ARF), which was approved by the HealthSciences Scientific Ethics Committee of Pontificia Universidad Católica de Chile. Critically ill patients connected to mechanicalventilation (MV) more than 48 hours, with PaO2/FiO2 <300 mmHg, and in whom the physician planned to perform a spontaneousventilation test (SBT) were included. After obtaining consent informed a catheter with an esophageal and gastric balloon andelectrodes to record the electrical activity of the diaphragm (EAdi) were installed. Moreover, an electrical impedance tomography(EIT) around the chest was connected, arterial and venous blood gases were recorded, in addition to the usual clinical signs.After extubation, the patients were connected to HFNC set at 50 L/min for one hour and conventional oxygen therapy (venturimask) for one hour in a random sequence.Results:Nine patients (6 men) aged 60.7 ± 10.0 years were included. Patients wereconnected to MV for 6.6 ± 3.2 days. Compared with conventional oxygen therapy, HFNC significantly reduces the respiratoryeffort observed by a reduction of esophageal pressure swings (ΔPes)(p= 0.006) and pressure-time product (PTPes) (p= 0.047)of 30% and 27%, respectively. In the HFNC period, the end-expiratory lung impedance (p< 0.001) and dynamic lung compliance(VT/ΔPes) (p= 0.041) was significantly higher. However, no differences were observed in tidal volume (p= 0.255), electricalactivity of the diaphragm (ΔEAdi) (p= 0.104), Neuro-ventilatory efficiency (p= 0.262), and respiratory rate (RR) (p= 0.299)compared to the period of conventional oxygen therapy. Finally, the PaO2 / FiO2 ratio was also higher in the HFNC period (p =0.029).Conclusion:The use of HFNC in the post-extubation period in patients with acute respiratory failure reduces work ofbreathing and is capable of increasing end-expiratory lung volume, dynamic compliance, and gas exchange.
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    The Challenge by Multiple Environmental and Biological Factors Induce Inflammation in Aging: Their Role in the Promotion of Chronic Disease
    (2020) Bachmann Barron, María Consuelo; Bellalta Bremer, Sofia Paz; Basoalto Escobar, Roque Ignacio; Gómez Valenzuela, Fernán Daniel; Jalil Contreras, Yorschua Frederick; Lepez Rivera, Macarena Paz; Matamoros, José Anibal; Von Bernhardi Montgomery, Rommy Edth B.
    The aging process is driven by multiple mechanisms that lead to changes in energy production, oxidative stress, homeostatic dysregulation and eventually to loss of functionality and increased disease susceptibility. Most aged individuals develop chronic low-grade inflammation, which is an important risk factor for morbidity, physical and cognitive impairment, frailty, and death. At any age, chronic inflammatory diseases are major causes of morbimortality, affecting up to 5-8% of the population of industrialized countries. Several environmental factors can play an important role for modifying the inflammatory state. Genetics accounts for only a small fraction of chronic-inflammatory diseases, whereas environmental factors appear to participate, either with a causative or a promotional role in 50% to 75% of patients. Several of those changes depend on epigenetic changes that will further modify the individual response to additional stimuli. The interaction between inflammation and the environment offers important insights on aging and health. These conditions, often depending on the individual's sex, appear to lead to decreased longevity and physical and cognitive decline. In addition to biological factors, the environment is also involved in the generation of psychological and social context leading to stress. Poor psychological environments and other sources of stress also result in increased inflammation. However, the mechanisms underlying the role of environmental and psychosocial factors and nutrition on the regulation of inflammation, and how the response elicited for those factors interact among them, are poorly understood. Whereas certain deleterious environmental factors result in the generation of oxidative stress driven by an increased production of reactive oxygen and nitrogen species, endoplasmic reticulum stress, and inflammation, other factors, including nutrition (polyunsaturated fatty acids) and behavioral factors (exercise) confer protection against inflammation, oxidative and endoplasmic reticulum stress, and thus ameliorate their deleterious effect. Here, we discuss processes and mechanisms of inflammation associated with environmental factors and behavior, their links to sex and gender, and their overall impact on aging.