Browsing by Author "Retamal Montes, Jaime Alejandro"

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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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    Mechanical Power of Ventilation: From Computer to Clinical Implications
    (2023) Damiani Rebolledo, L. Felipe; Basoalto Escobar, Roque Ignacio; Retamal Montes, Jaime Alejandro; Bruhn Cruz, Alejandro Rodrigo; Bugedo Tarraza, Guillermo Jaime
    Mechanical ventilation is a lifesaving intervention that may also induce further lung injury by exerting excessive mechanical forces on susceptible lung tissue, a phenomenon termed ventilator-induced lung injury (VILI). The concept of mechanical power (MP) aims to unify in one single variable the contribution of the different ventilatory parameters that could induce VILI by measuring the energy transfer to the lung over time. Despite an increasing amount of evidence demonstrating that high MP values can be associated with VILI development in experimental studies, the evidence regarding the association of MP and clinical outcomes remains controversial. In the present review, we describe the different determinants of VILI, the concept and computation of MP, and discuss the experimental and clinical studies related to MP. Currently, due to different limitations, the clinical application of MP is debatable. Further clinical studies are required to enhance our understanding of the relationship between MP and the development of VILI, as well as its potential impact on clinical outcomes.
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    Role of endothelial dysfunction on tolerance to supine position in patients with acute respiratory distress syndrome on mechanical ventilation
    (2024) Bachmann Barron, Maria Consuelo; Retamal Montes, Jaime Alejandro; Pontificia Universidad Católica de Chile . Facultad de Medicina
    Introduction: The prone position is a maneuver frequently used to improve oxygenation inpatients with ARDS on mechanical ventilation. Physiologically, optimization of gas exchangeoccurs by recruiting the dorsal regions of the lung, improving the ventilation/perfusion (V/Q)ratio. Despite the benefits, this position presents complications. Therefore, it is important toclearly know its indications and duration time. Prolonged use of the prone position (more than16 hours) can be associated with severe muscle weakness among other complications, whileits use for short and repeated periods is associated with accidents, increase workload, and agreater number of days in IMV. Therefore, it is important to be able to precisely determine themoment in which the patient is ready to be supinated.Through EIT it has been shown that both in healthy and ARDS conditions, the distribution ofpulmonary ventilation is predominantly dorsal in prone, and ventral in supine position. Whileperfusion under normal and pathological conditions presents a dorsal predominance. Itwould be expected that, with adequate endothelial function, the presence of hypoxicpulmonary vasoconstriction allows the redistribution of pulmonary perfusion towardsnormally aerated regions, allowing optimal gas exchange. We hypothesized thatmechanically ventilated in prone position ARDS patients, with endothelial dysfunction are notcapable of regulate pulmonary perfusion and, therefore, increasing their V/Q imbalance, withthe position change worsening oxygenation.Methods: Observational quasi-experimental clinical study in patients admitted to the ICU ofthe UC-CHRISTUS Clinical Hospital, in Santiago, Chile. Patients with diagnosis of ARDSconnected to IMV in prone position were included. Endothelial function was assessed atbaseline through flow-mediated vasodilation and NIRS. Hemodynamic and ventilatoryparameters, ABG, and distribution of ventilation and perfusion through EIT were evaluated inprone and supine for analysis of shunt, dead space, and V/Q mismatch. Lung aeration wasevaluated with lung ultrasound and computed tomography. Supine position intolerance wasdefined as the need for a second prone cycle within the first 24 hours after the switch.Results: This analysis included 20 patients, of whom 13 tolerated the change in position. Nocorrelation was found between the V/Q ratio and tolerance to position change. There werealso no associations found between clinical (NIRS and FMD) and biochemical (bloodmarkers) assessments of endothelial dysfunction and V/Q ratio imbalance. However, othervariables were shown to play a relevant role in tolerance outcomes. The failed group exhibiteda more widespread distribution of lung injury assessed by CT compared to the successfulgroup (local injury). Additionally, the failed group showed significantly higher values of drivingpressure and PaCO2 than the successful group, and these differences were found during boththe prone and supine periods.Conclusions: No relation was observed between tolerance to position change and thepresence of endothelial dysfunction, and we have not been able to find the existence ofpredictive patterns of tolerance. Respiratory mechanics and pulmonary injury distributioncould be the determining factor.