Browsing by Author "Retamal, Jaime"
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Item A physiological approach to understand the role of respiratory effort in the progression of lung injury in SARS-CoV-2 infection(2020) Cruces, Pablo; Retamal, Jaime; Hurtado, Daniel E.; Erranz, Benjamín; Iturrieta, Pablo; González, Carlos; Díaz, FrancoDeterioration of lung function during the first week of COVID-19 has been observed when patients remain with insufficient respiratory support. Patient self-inflicted lung injury (P-SILI) is theorized as the responsible, but there is not robust experimental and clinical data to support it. Given the limited understanding of P-SILI, we describe the physiological basis of P-SILI and we show experimental data to comprehend the role of regional strain and heterogeneity in lung injury due to increased work of breathing. In addition, we discuss the current approach to respiratory support for COVID-19 under this point of viewItem Extracorporeal membrane oxygenation improves survival in a novel 24-hour pig model of severe acute respiratory distress syndrome(e-Century Pub. Corp, 2016) Araos, Joaquín; Alegría, Leyla; García, Patricio; Damiani, Felipe; Tapia, Pablo; Soto, Dagoberto; Salomón, Tatiana; Rodríguez, Felipe; Amthauer, Macarena; Erranz, Benjamín; Castro, Gabriel; Carreño, Pamela; Medina, Tania; Retamal, Jaime; Cruces, Pablo; Bugedo, Guillermo; Bruhn, AlejandroExtracorporeal membrane oxygenation (ECMO) is increasingly being used to treat severe acute respiratory distress syndrome (ARDS). However, there is limited clinical evidence about how to optimize the technique. Experimental research can provide an alternative to fill the actual knowledge gap. The purpose of the present study was to develop and validate an animal model of acute lung injury (ALI) which resembled severe ARDS, and which could be successfully supported with ECMO. Eighteen pigs were randomly allocated into three groups: sham, ALI, and ALI + ECMO. ALI was induced by a double-hit consisting in repeated saline lavage followed by a 2-hour period of injurious ventilation. All animals were followed up to 24 hours while being ventilated with conventional ventilation (tidal volume 10 ml/kg). The lung injury model resulted in severe hypoxemia, increased airway pressures, pulmonary hypertension, and altered alveolar membrane barrier function, as indicated by an increased protein concentration in bronchoalveolar fluid, and increased wet/dry lung weight ratio. Histologic examination revealed severe diffuse alveolar damage, characteristic of ARDS. Veno-venous ECMO was started at the end of lung injury induction with a flow > 60 ml/kg/min resulting in rapid reversal of hypoxemia and pulmonary hypertension. Mortality was 0, 66.6 and 16.6% in the SHAM, ALI and ALI + ECMO groups, respectively (p < 0.05). This is a novel clinically relevant animal model that can be used to optimize the approach to ECMO and foster translational research in extracorporeal lung support.Item Near-apneic ventilation decreases lung injury and fibroproliferation in an ARDS model with ECMO(2019) Araos, Joaquín; Alegría, Leyla; Garcia, Patricio; Cruces, Pablo; Soto, Dagoberto; Erranz, Benjamín; Amthauer, Macarena; Salomon, Tatiana; Medina, Tania; Rodríguez, Felipe; Ayala, Pedro; Borzone, Gisella R.; Meneses, Manuel; Damiani, Felipe; Retamal, Jaime; Cornejo, Rodrigo; Bugedo, Guillermo; Bruhn, AlejandroRationale: There is wide variability in mechanical ventilation settings during ECMO in ARDS patients. Although lung rest is recommended to prevent further injury, there is no evidence to support it. Objectives: To determine whether near-apneic ventilation decreases lung injury in a pig model of ARDS supported with ECMO. Methods: Pigs (26-36kg; n=24) were anesthetized and connected to mechanical ventilation. In 18 animals lung injury was induced by a double-hit consisting in repeated saline lavages followed by 2 hours of injurious ventilation. Then, animals were connected to high-flow veno-venous ECMO, and randomized into 3 groups: Non-protective (PEEP 5 cmH2O, tidal volume 10 ml/kg, respiratory rate 20 bpm); Conventional-protective (PEEP 10 cmH2O, tidal volume 6 ml/kg, respiratory rate 20 bpm); Near-apneic (PEEP 10 cmH2O, driving pressure 10 cmH2O, respiratory rate 5 bpm). Six other pigs were used as Sham. All groups were maintained during the 24-hour study period. Measurements and Main Results: Minute ventilation and mechanical power were lower in the Near-apneic group, but no differences were observed in oxygenation or compliance. Lung histology revealed less injury in the Near-apneic group. Extensive immunohistochemical staining for myofibroblasts and pro-collagen III was observed in the Non-protective group, with the Near-apneic group exhibiting the least alterations. Near- apneic group showed significantly less matrix-metalloproteinase-2 and -9 activity. Histological lung injury and fibroproliferation scores were positively correlated with driving pressure and mechanical power.