Browsing by Author "Brito, Roberto"

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    Double cycling with breath-stacking during partial support ventilation in ARDS: Just a feature of natural variability?
    (2025) Brito, Roberto; Morais, Caio C. A.; Arellano, Daniel H.; Gajardo, Abraham I. J.; Bruhn, Alejandro; Brochard, L.; Amato, Marcelo B. P.; Cornejo, Rodrigo A.
    Background Double cycling with breath-stacking (DC/BS) during controlled mechanical ventilation is considered potentially injurious, reflecting a high respiratory drive. During partial ventilatory support, its occurrence might be attributable to physiological variability of breathing patterns, reflecting the response of the mode without carrying specific risks. Methods This secondary analysis of a crossover study evaluated DC/BS events in hypoxemic patients resuming spontaneous breathing in cross-over under neurally adjusted ventilatory assist (NAVA), proportional assist ventilation (PAV +), and pressure support ventilation (PSV). DC/BS was defined as two inspiratory cycles with incomplete exhalation. Measurements included electrical impedance signal, airway pressure, esophageal and gastric pressures, and flow. Breathing variability, dynamic compliance (CLdyn), and end-expiratory lung impedance (EELI) were analyzed. Results Twenty patients under assisted breathing, with a median of 9 [5–14] days on mechanical ventilation, were included. DC/BS was attributed to either a single (42%) or two apparent consecutive inspiratory efforts (58%). The median [IQR] incidence of DC/BS was low: 0.6 [0.1–2.6] % in NAVA, 0.0 [0.0–0.4] % in PAV + , and 0.1 [0.0–0.4] % in PSV (p = 0.06). DC/BS events were associated with patient’s coefficient of variability for tidal volume (p = 0.014) and respiratory rate (p = 0.011). DC/BS breaths exhibited higher tidal volume, muscular pressure and regional stretch compared to regular breaths. Post-DC/BS cycles frequently exhibited improved EELI and CLdyn, with no evidence of expiratory muscle activation in 63% of cases. Conclusions DC/BS events during partial ventilatory support were infrequent and linked to breathing variability. Their frequency and physiological effects on lung compliance and EELI resemble spontaneous sighs and may not be considered a priori as harmful.
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    Estimation of changes in cyclic lung strain by electrical impedance tomography: Proof-of-concept study
    (2021) Cornejo, Rodrigo; Iturrieta, Pablo Cristián; Olegári, Tayran M. M.; Hurtado Sepúlveda, Daniel; Kajiyama, Carolina; Arellan, Daniel; Bruhn, Alejandro; Guiñez, Dannette; Cerda, María A.; Brito, Roberto; Gajardo, Abraham I. J.; Lazo, Marioli; López, Lorena; Morais, Caio C. A.; Gonzále, Sedric; Zavala, Miguel; Rojas, Verónica; Medel, Juan N.; Ramos, Cristóbal; Estuardo, Nivia
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    Pendelluft in hypoxemic patients resuming spontaneous breathing: proportional modes versus pressure support ventilation
    (2023) Arellano, Daniel H.; Brito, Roberto; Morais, Caio C. A.; Ruiz-Rudolph, Pablo; Gajardo, Abraham I. J.; Guiñez, Dannette V.; Lazo, Marioli T.; Ramirez, Ivan; Rojas, Verónica A.; Bruhn, Alejandro; Cerda, María A.; Medel, Juan N.; Illanes, Victor; Estuardo, Nivia R.; Brochard, Laurent J.; Amato, Marcelo B. P.; Cornejo, Rodrigo A.
    Background: Internal redistribution of gas, referred to as pendelluft, is a new potential mechanism of effort-dependent lung injury. Neurally-adjusted ventilatory assist (NAVA) and proportional assist ventilation (PAV +) follow the patient’s respiratory effort and improve synchrony compared with pressure support ventilation (PSV). Whether these modes could prevent the development of pendelluft compared with PSV is unknown. We aimed to compare pendelluft magnitude during PAV + and NAVA versus PSV in patients with resolving acute respiratory distress syndrome (ARDS). Methods: Patients received either NAVA, PAV + , or PSV in a crossover trial for 20-min using comparable assistance levels after controlled ventilation (> 72 h). We assessed pendelluft (the percentage of lost volume from the non-dependent lung region displaced to the dependent region during inspiration), drive (as the delta esophageal swing of the first 100 ms [ΔPes 100 ms]) and inspiratory effort (as the esophageal pressure–time product per minute [PTPmin]). We performed repeated measures analysis with post-hoc tests and mixed-effects models. Results: Twenty patients mechanically ventilated for 9 [5–14] days were monitored. Despite matching for a similar tidal volume, respiratory drive and inspiratory effort were slightly higher with NAVA and PAV + compared with PSV (ΔPes 100 ms of –2.8 [−3.8–−1.9] cm H2O, −3.6 [−3.9–−2.4] cm H2O and −2.1 [−2.5–−1.1] cm H2O, respectively, p < 0.001 for both comparisons; PTPmin of 155 [118–209] cm H2O s/min, 197 [145–269] cm H2O s/min, and 134 [93–169] cm H2O s/min, respectively, p < 0.001 for both comparisons). Pendelluft magnitude was higher in NAVA (12 ± 7%) and PAV + (13 ± 7%) compared with PSV (8 ± 6%), p < 0.001. Pendelluft magnitude was strongly associated with respiratory drive (β = -2.771, p-value < 0.001) and inspiratory effort (β = 0.026, p  < 0.001), independent of the ventilatory mode. A higher magnitude of pendelluft in proportional modes compared with PSV existed after adjusting for PTPmin (β = 2.606, p = 0.010 for NAVA, and β = 3.360, p = 0.004 for PAV +), and only for PAV + when adjusted for respiratory drive (β = 2.643, p = 0.009 for PAV +). Conclusions: Pendelluft magnitude is associated with respiratory drive and inspiratory effort. Proportional modes do not prevent its occurrence in resolving ARDS compared with PSV.
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    Small extracellular vesicles from pregnant women with maternal supraphysiological hypercholesterolemia impair endothelial cell function in vitro
    (2023) Contreras-Duarte, Susana; Escalona-Rivano, Rodrigo; Cantin, Claudette; Valdivia, Pascuala; Zapata, David; Carvajal, Lorena; Brito, Roberto; Cerda, Alvaro; Illanes, Sebastian; Gutierrez, Jaime; Leiva, Andrea
    Maternal physiological hypercholesterolemia MPH, maternal total cholesterol (TC) levels at term of pregnancy <280 mg/dL) occurs to assure fetal development. Maternal supraphysiological hypercholesterolemia (MSPH, TC levels >280 mg/dL) is a pathological condition associated with maternal, placental, and fetal endothelial dysfunction and early neonatal atherosclerosis development. Small extracellular vesicles (sEVs) are delivered to the extracellular space by different cells, where they modulate cell functions by transporting active signaling molecules, including proteins and miRNA.Aim: To determine whether sEVs from MSPH women could alter the function of endothelial cells (angiogenesis, endothelial activation and nitric oxide synthesis capacity).Methods: This study included 24 Chilean women (12 MPH and 12 MSPH). sEVs were isolated from maternal plasma and characterized by sEV markers (CD9, Alix and HSP70), nanoparticle tracking analysis, transmission electron microscopy, and protein and cholesterol content. The endothelial cell line HMEC-1 was used to determine the uptake of labeled sEVs and the effects of sEVs on cell viability, endothelial tube formation, endothelial cell activation, and endothelial nitric oxide expression and function.Results: In MSPH women, the plasma concentration of sEVs was increased compared to that in MPH women. MSPH-sEVs were highly taken up by HMEC-1 cells and reduced angiogenic capacity and the expression and activity of eNOS without changing cell viability or endothelial activation compared to MPH-sEVs. Conclusion: sEVs from MSPH women impair angiogenesis and nitric oxide synthesis in endothelial cells, which could contribute to MSPH-associated endothelial dysfunction.