Browsing by Author "Retamal, Jaime"

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    A machine-learning regional clustering approach to understand ventilator-induced lung injury: a proof-of-concept experimental study
    (2024) Cruces, Pablo; Retamal, Jaime; Damián, Andrés; Lago, Graciela; Blasina, Fernanda; Oviedo, Vanessa; Medina, Tania; Pérez, Agustín; Vaamonde, Lucía; Dapueto, Rosina; González-Dambrauskas, Sebastian; Serra, Alberto; Monteverde-Fernandez, Nicolas; Namías, Mauro; Martínez, Javier; Hurtado, Daniel E.
    Background The spatiotemporal progression and patterns of tissue deformation in ventilator-induced lung injury (VILI) remain understudied. Our aim was to identify lung clusters based on their regional mechanical behavior over space and time in lungs subjected to VILI using machine-learning techniques. Results Ten anesthetized pigs (27±2 kg) were studied. Eight subjects were analyzed. End-inspiratory and endexpiratory lung computed tomography scans were performed at the beginning and after 12 h of one-hit VILI model. Regional image-based biomechanical analysis was used to determine end-expiratory aeration, tidal recruitment, and volumetric strain for both early and late stages. Clustering analysis was performed using principal component analysis and K-Means algorithms. We identifed three diferent clusters of lung tissue: Stable, Recruitable Unstable, and Non-Recruitable Unstable. End-expiratory aeration, tidal recruitment, and volumetric strain were signifcantly diferent between clusters at early stage. At late stage, we found a step loss of end-expiratory aeration among clusters, lowest in Stable, followed by Unstable Recruitable, and highest in the Unstable Non-Recruitable cluster. Volumetric strain remaining unchanged in the Stable cluster, with slight increases in the Recruitable cluster, and strong reduction in the Unstable Non-Recruitable cluster. Conclusions VILI is a regional and dynamic phenomenon. Using unbiased machine-learning techniques we can identify the coexistence of three functional lung tissue compartments with diferent spatiotemporal regional biomechanical behavior.
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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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    Airway humidification practices in Chilean intensive care units
    (SOC MEDICA SANTIAGO, 2012) Retamal, Jaime; Castillo, Juan; Bugedo, Guillermo; Bruhn, Alejandro
    Airway humidification practices in Chilean intensive care units Background: In patients with an artificial airway, inspired gases can be humidified and heated using a passive (heat and moisture exchange filter - HMEF), or an active system (heated humidifier). Aim: To assess how humidification is carried out and what is the usual clinical practice in this field in Chilean intensive care units (ICUs). Material and Methods: A specific survey to evaluate humidification system features as well as caregivers' preferences regarding humidification systems, was carried out on the same day in all Chilean ICUs. Results: Fifty-five ICUs were contacted and 44 of them completed the survey. From a total of 367 patients, 254 (69%) required humidification because they were breathing through an artificial airway. A heated humidifier was employed only in 12 patients (5%). Forty-three ICUs (98%) used HMEF as their routine humidification system. In 52% of surveyed ICUs, heated humidifiers were not available. Conclusions: In Chile the main method to humidify and heat inspired gases in patients with an artificial airway is the HMEE Although there are clear indications for the use of heated humidifiers, they are seldom employed. (Rev Med Chile 2012; 140: 1425-1430).
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    Dynamic changes of hepatic vein Doppler velocities predict preload responsiveness in mechanically ventilated critically ill patients
    (2024) Bruna, Mario; Alfaro, Sebastián; Muñoz Ferrada, Felipe Ignacio; Cisternas, Liliana; González, Cecilia; Conlledo, Rodrigo; Ulloa Morrison, Rodrigo; Huilcaman, Marcos; Retamal, Jaime; Castro López, Ricardo; Rola, Philippe; Wong, Adrian; Argaiz, Eduardo R.; Contreras, Roberto; Hernández P., Glenn; Kattan Tala, Eduardo José
    Background: Assessment of dynamic parameters to guide fluid administration is one of the mainstays of current resuscitation strategies. Each test has its own limitations, but passive leg raising (PLR) has emerged as one of the most versatile preload responsiveness tests. However, it requires real-time cardiac output (CO) measurement either through advanced monitoring devices, which are not routinely available, or echocardiography, which is not always feasible. Analysis of the hepatic vein Doppler waveform change, a simpler ultrasound-based assessment, during a dynamic test such as PLR could be useful in predicting preload responsiveness. The objective of this study was to assess the diagnostic accuracy of hepatic vein Doppler S and D-wave velocities during PLR as a predictor of preload responsiveness. Methods: Prospective observational study conducted in two medical–surgical ICUs in Chile. Patients in circulatory failure and connected to controlled mechanical ventilation were included from August to December 2023. A baseline ultrasound assessment of cardiac function was performed. Then, simultaneously, ultrasound measurements of hepatic vein Doppler S and D waves and cardiac output by continuous pulse contour analysis device were performed during a PLR maneuver. Results: Thirty-seven patients were analyzed. 63% of the patients were preload responsive defined by a 10% increase in CO after passive leg raising. A 20% increase in the maximum S wave velocity after PLR showed the best diagnostic accuracy with a sensitivity of 69.6% (49.1–84.4) and specificity of 92.8 (68.5–99.6) to detect preload responsiveness, with an area under curve of receiving operator characteristic (AUC–ROC) of 0.82 ± 0.07 (p = 0.001 vs. AUC–ROC of 0.5). D-wave velocities showed worse diagnostic accuracy. Conclusions: Hepatic vein Doppler assessment emerges as a novel complementary technique with adequate predictive capacity to identify preload responsiveness in patients in mechanical ventilation and circulatory failure. This technique could become valuable in scenarios of basic hemodynamic monitoring and when echocardiography is not feasible. Future studies should confirm these results.
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    How far are we from predicting multi-drug interactions during treatment for COVID-19 infection?
    (WILEY, 2022) Lozano, Benjamin; Santibanez, Javier; Severino, Nicolas; Saldias, Cristina; Vera, Magdalena; Retamal, Jaime; Torres, Soledad; Barrera, Nelson P.
    Seriously ill patients infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and hospitalized in intensive care units (ICUs) are commonly given a combination of drugs, a process known as multi-drug treatment. After extracting data on drug-drug interactions with clinical relevance from available online platforms, we hypothesize that an overall interaction map can be generated for all drugs administered. Furthermore, by combining this approach with simulations of cellular biochemical pathways, we may be able to explain the general clinical outcome. Finally, we postulate that by applying this strategy retrospectively to a cohort of patients hospitalized in ICU, a prediction of the timing of developing acute kidney injury (AKI) could be made. Whether or not this approach can be extended to other diseases is uncertain. Still, we believe it represents a valuable pharmacological insight to help improve clinical outcomes for severely ill patients.
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    Physiological and clinical effects of trunk inclination adjustment in patients with respiratory failure: a scoping review and narrative synthesis
    (2024) Benites, Martín H.; Zapata Canivilo, Marcelo; Poblete, Fabian; Labbe, Francisco; Battiato, Romina; Ferre, Andrés; Dreyse, Jorge; Bugedo, Guillermo; Bruhn, Alejandro; Costa, Eduardo L. V.; Retamal, Jaime
    Background Adjusting trunk inclination from a semi-recumbent position to a supine-flat position or vice versa in patients with respiratory failure significantly affects numerous aspects of respiratory physiology including respiratory mechanics, oxygenation, end-expiratory lung volume, and ventilatory efficiency. Despite these observed effects, the current clinical evidence regarding this positioning manoeuvre is limited. This study undertakes a scoping review of patients with respiratory failure undergoing mechanical ventilation to assess the effect of trunk inclination on physiological lung parameters. Methods The PubMed, Cochrane, and Scopus databases were systematically searched from 2003 to 2023. Interventions: Changes in trunk inclination. Measurements: Four domains were evaluated in this study: 1) respiratory mechanics, 2) ventilation distribution, 3) oxygenation, and 4) ventilatory efficiency. Results After searching the three databases and removing duplicates, 220 studies were screened. Of these, 37 were assessed in detail, and 13 were included in the final analysis, comprising 274 patients. All selected studies were experimental, and assessed respiratory mechanics, ventilation distribution, oxygenation, and ventilatory efficiency, primarily within 60 min post postural change. Conclusion In patients with acute respiratory failure, transitioning from a supine to a semi-recumbent position leads to decreased respiratory system compliance and increased airway driving pressure. Additionally, C-ARDS patients experienced an improvement in ventilatory efficiency, which resulted in lower PaCO2 levels. Improvements in oxygenation were observed in a few patients and only in those who exhibited an increase in EELV upon moving to a semi-recumbent position. Therefore, the trunk inclination angle must be accurately reported in patients with respiratory failure under mechanical ventilation.
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    Reduction of Respiratory Rate in COVID-19-Associated ARDS
    (2022) Damiani, L. Felipe; Oviedo, Vanessa; Alegria, Leyla; Soto, Dagoberto; Basoalto, Roque; Consuelo Bachmann, M.; Jalil Contreras, Yorschua Frederick; Santis, Cesar; Vera, Magdalena; Retamal, Jaime; Bruhn, Alejandro; Bugedo, Guillermo
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    The impact of norepinephrine dose reporting heterogeneity on mortality prediction in septic shock patients
    (2024-07-03) Morales, Sebastian; Wendel-Garcia, Pedro D.; Ibarra-Estrada, Miguel; Jung, Christian; Castro, Ricardo; Retamal, Jaime; Cortinez, Luis I.; Severino, Nicolás; Kiavialaitis, Greta E.; Ospina-Tascón, Gustavo; Bakker, Jan; Hernández, Glenn; Kattan, Eduardo
    Background: Norepinephrine (NE) is a cornerstone drug in the management of septic shock, with its dose being used clinically as a marker of disease severity and as mortality predictor. However, variations in NE dose reporting either as salt formulations or base molecule may lead to misinterpretation of mortality risks and hinder the process of care. Methods: We conducted a retrospective analysis of the MIMIC-IV database to assess the impact of NE dose reporting heterogeneity on mortality prediction in a cohort of septic shock patients. NE doses were converted from the base molecule to equivalent salt doses, and their ability to predict 28-day mortality at common severity dose cut-offs was compared. Results: 4086 eligible patients with septic shock were identified, with a median age of 68 [57–78] years, an admission SOFA score of 7 [6–10], and lactate at diagnosis of 3.2 [2.4–5.1] mmol/L. Median peak NE dose at day 1 was 0.24 [0.12–0.42] μg/kg/min, with a 28-day mortality of 39.3%. The NE dose showed significant heterogeneity in mortality prediction depending on which formulation was reported, with doses reported as bitartrate and tartrate presenting 65 (95% CI 79–43)% and 67 (95% CI 80–47)% lower ORs than base molecule, respectively. This divergence in prediction widened at increasing NE doses. When using a 1 μg/kg/min threshold, predicted mortality was 54 (95% CI 52–56)% and 83 (95% CI 80–87)% for tartrate formulation and base molecule, respectively. Conclusions: Heterogeneous reporting of NE doses significantly affects mortality prediction in septic shock. Standardizing NE dose reporting as base molecule could enhance risk stratification and improve processes of care. These findings underscore the importance of consistent NE dose reporting practices in critical care settings.