Browsing by Author "Bruhn Cruz, Alejandro Rodrigo"

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    Acute Bronchiolitis in Infants on Invasive Mechanical Ventilation: Physiology Study of Airway Closure
    (2025) Varela Ortiz, Javier Humberto; Aranis, Nadine; Varas, Francisca; Vallejos, Martina; Bruhn Cruz, Alejandro Rodrigo
    Objectives: This study aimed to explore whether airway closure can be detected in patients with severe acute bronchiolitis on invasive mechanical ventilation.Design: Single-center prospective physiologic study carried out in 2023-2024.Setting: PICU in a tertiary-care general hospital.Patients: Infants with acute bronchiolitis undergoing invasive mechanical ventilation.Interventions: Under deep sedation and neuromuscular blockade, the mechanical ventilator, in a volume-controlled mode, was transiently set with a respiratory rate of five breaths/min, a tidal volume of 6 mL/kg of ideal body weight, positive end-expiratory pressure 0 cm H2O, a flow rate of 2 L/min, an inspiratory-expiratory ratio of 1:1, and a Fio2 of 1.0. After recording three breath cycles, the patient was returned to baseline ventilatory settings.Measurements and main results: We identified the presence of airway closure through the low-flow pressure-volume curve obtained from a pneumotachometer with a flow sensor placed at the Y-piece and simultaneously from the pressure-impedance curve and ventilation maps acquired using electrical impedance tomography. We included 12 patients, and airway closure was detected in seven of them. The median (interquartile range [IQR]) airway opening pressure was 14 cm H2O (IQR, 11-17 cm H2O). Patients with airway closure exhibited high levels of driving pressure, with a median of 16 cm H2O (IQR, 11-17 cm H2O), and low levels of respiratory system compliance, with a median of 0.41 mL/cm H2O/kg (IQR, 0.38-0.59 mL/cm H2O/kg). When these parameters were corrected for airway opening pressure, there was a significant decrease in driving pressure to 9 cm H2O (IQR, 8-12 cm H2O; p = 0.018) and a significant increase in respiratory system compliance to 0.70 mL/cm H2O/kg (IQR, 0.53-0.81 mL/cm H2O/kg; p = 0.018).Conclusions: Airway closure requiring high opening pressures can be detected in ventilated infants with acute bronchiolitis, and this phenomenon may impact respiratory mechanics.
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    Acute effect of dobutamine and amrinone on hemodynamics and splanchnic perfusion in septic shock patients
    (1999) Hernández, P. Glenn; Gigoux Muller, Jorge Alberto; Bugedo Tarraza, Guillermo; Castillo Fuenzalida, Luis Benito; Bruhn Cruz, Alejandro Rodrigo; Tomicic, Vinko; Dagnino Sepúlveda, Jorge Álvaro
    Background: Vasoactive drugs used in the reanimation of septic patients, can modify splanchnic perfusion. Aim: To compare the effects of dobutamine and amrinone on gastric intramucosal pH (pHi), lactate levels and hemodynamics in surgical patients with compensated septic shock. Patients and methods: Fourteen postoperative patients with abdominal sepsis and compensated septic shock (pHi < 7.32 or lactate > 2.5 mmol/l) were studied in a prospective, randomized, unblinded study. Patients were randomized to receive (Group 1, n = 7) dobutamine at 5 micrograms/Kg/min or (Group 2, n = 7) amrinone at 5 micrograms/Kg/min. Hemodynamic data, arterial lactate and pHi were measured before and 30, 60 and 120 minutes after starting drug infusion. Results: Both drugs were associated with a decrease in lactate levels. Dobutamine infusion, but not amrinone, increased gastric pHi, as well as cardiac index and oxygen delivery. Conclusions: An improvement in gastric pHi associated with an increase in oxygen delivery, was observed with dobutamine. Amrinone showed no effect at the fixed, low dose used in the study.
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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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    Adherence to low tidal volume in the transition to spontaneous ventilation in patients with acute respiratory failure in intensive care units in Latin America (SPIRAL): a study protocol
    (Associacao de Medicina Intensiva Brasileira - AMIB, 2024) Diniz-Silva, Fabia; Pinheiro, Bruno Valle; Reyes, Luis Felipe; Cavalcanti, Alexandre Biasi; Figueredo, Belinda; Rios, Fernando; Machado, Flávia Ribeiro; Preda, Gabriel; Bugedo Tarraza, Guillermo Jaime; Maia, Israel Silva; da Silveira, Leda Tomiko Yamada; Herrera, Luis; Jibaja, Manuel; Ibarra-Estrada, Miguel; Cestari, Mino; Nin, Nicolás; Roldan, Rollin; Dos Santos, Tiago Mendonça; Veiga, Viviane Cordeiro; Bruhn Cruz, Alejandro Rodrigo; Ferreira, Juliana Carvalho
    © 2024, Associacao de Medicina Intensiva Brasileira - AMIB. All rights reserved.Objective: Patients with acute respiratory failure often require mechanical ventilation to reduce the work of breathing and improve gas exchange; however, this may exacerbate lung injury. Protective ventilation strategies, characterized by low tidal volumes (≤ 8mL/kg of predicted body weight) and limited plateau pressure below 30cmH2O, have shown improved outcomes in patients with acute respiratory distress syndrome. However, in the transition to spontaneous ventilation, it can be challenging to maintain tidal volume within protective levels, and it is unclear whether low tidal volumes during spontaneous ventilation impact patient outcomes. We developed a study protocol to estimate the prevalence of low tidal volume ventilation in the first 24 hours of spontaneous ventilation in patients with hypoxemic acute respiratory failure and its association with ventilator-free days and survival. Methods: We designed a multicenter, multinational, cohort study with a 28-day follow-up that will include patients with acute respiratory failure, defined as a partial oxygen pressure/ fraction of inspired oxygen ratio < 300mmHg, in transition to spontaneous ventilation in intensive care units in Latin America. Results: We plan to include 422 patients in ten countries. The primary outcomes are the prevalence of low tidal volume in the first 24 hours of spontaneous ventilation and ventilator-free days on day 28. The secondary outcomes are intensive care unit and hospital mortality, incidence of asynchrony and return to controlled ventilation and sedation. Conclusion: In this study, we will assess the prevalence of low tidal volume during spontaneous ventilation and its association with clinical outcomes, which can inform clinical practice and future clinical trials.
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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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    Closing the critical care knowledge gap: the importance of publications from low-income and middle-income countries
    (2024) Figueira Salluh, Jorge Ibrain; Maccagnan Pinheiro Besen, Bruno Adler; González-Dambrauskas, Sebastián; Mer, Mervyn; Bruhn Cruz, Alejandro Rodrigo; Ranzani, Otavio T.; Nassar Junior, Antonio Paulo; Pisani, Luigi
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    Efectos fisiológicos de la ventilación mecánica no invasiva y cánula nasal de alto flujo en el periodo postextubación de pacientes críticamente enfermos con alto riesgo de falla de destete
    (2024) Basoalto Escobar, Roque Ignacio; Bruhn Cruz, Alejandro Rodrigo; Pontificia Universidad Católica de Chile. Facultad de Medicina
    Introducción: se estima que entre el 10% y el 20% de los pacientes experimentan falla de destete de la ventilación mecánica (VM), incrementándose al 30% en aquellos considerados de alto riesgo. Frente a este escenario, la ventilación no invasiva (VNI) y la cánula nasal de alto flujo (CNAF) son las estrategias que han demostrado ser efectivas para prevenir la falla de destete. Los efectos fisiológicos de ambas podrían diferir lo cual podría tener implicancias para una selección más personalizada del soporte postextubación. Sin embargo, no existen estudios que hayan comparado los efectos fisiológicos de VNI versus CNAF en la fase postextubación.Objetivo: Comparar los efectos de la VNI versus CNAF sobre el trabajo respiratorio, función respiratoria, aireación pulmonar, hemodinamia y estrés cardiovascular, durante el periodo postextubación de pacientes críticamente enfermos con alto riesgo de falla de destete.Método: El estudio corresponde a un ensayo clínico aleatorizado de tipo cruzado en pacientes con VM por más de 48 horas y categorizados con alto riesgo de falla de destete. Durante el estudio los pacientes fueron monitorizados con un catéter esofágico/gástrico y electromiografía de diafragma para evaluar el trabajo respiratorio. Adicionalmente, fueron monitoreados con tomografía por impedancia eléctrica para evaluar cambios en la aireación pulmonar. Postextubación fueron sometidos secuencialmente a VNI y CNAF por una hora en orden aleatorio. Al final de cada periodo de intervención se evaluó trabajo respiratorio, función respiratoria, patrón de ventilación, hemodinamia, NT-ProBNP y troponinas T ultrasensibles.Resultados: La población estudiada (n= 22) presentó una edad 66 [47 – 76] años, con una mediana de conexión a VM 7 [4 - 10] días. El análisis de esfuerzo respiratorio mostró una reducción significativa en el producto presión tiempo (PTP) por minuto y en la variación de presión esofágica (ΔPes) con VNI en comparación con CNAF (90 [63 - 125] vs. 109 [76 - 183] cmH2O.s/min; p= 0,013 y 6,1 [4,0 – 8,1] vs. 7,05 [4,9 – 9,7] cmH2O; p= 0,021, respectivamente). Además, se observó una reducción de frecuencia respiratoria durante el período de VNI (20 [15 - 24] vs. 22 [17 -23]; p= 0,022), un aumento significativo en el volumen corriente (473 ± 153 vs. 371 ± 141 ml; p= 0,001) y en el volumen minuto (9,5 ± 3,1 vs. 8,3 ± 2,8 L/min; p= 0,036) durante el periodo de VNI. Sin embargo, no se encontraron diferencias en el volumen de fin de espiración global (ΔEELV), actividad eléctrica del diafragma, hemodinamia ni en los biomarcadores de estrés cardiovascular. Notablemente, al compararlas con el periodo basal de oxigenoterapia convencional tanto VNI como CNAF demostraron una reducción en el esfuerzo respiratorio, frecuencia respiratoria y un aumento significativo en ΔEELV. Conclusión: Tanto VNI como CNAF producen una marcada disminución del trabajo respiratorio en pacientes con alto riesgo de falla de destete durante la fase postextubación. Sin embargo, el impacto de VNI es superior a la CNAF, particularmente en los pacientes que presentan un mayor nivel de trabajo respiratorio basal. Además, tanto VNI como CNAF inducen un aumento del EELV de magnitud comparable, pero sólo VNI aumenta el volumen corriente y modifica el patrón respiratorio.
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    Efectos fisiologicos de las terapias de soporte respiratorio no invasivo y su potencial rol postextubación
    (2021) Basoalto Escobar, Roque Ignacio; Jalil Contreras, Yorschua Frederick; Díaz Patino, Orlando Alberto; Bruhn Cruz, Alejandro Rodrigo
    Posterior a una extubación programada existe un porcentaje de pacientes que fracasa y requiere reintubación (~20%), este evento es conocido como fracaso de extubación, el cual se asocia con mayor morbimortalidad. Para prevenir el fracaso de extubación se han propuesto terapias como la ventilación no invasiva (VNI) y la cánula nasal de alto flujo (CNAF). Estas terapias son capaces de entregar soporte respiratorio postextubación y justifican su uso en los efectos fisiológicos que son capaces de inducir, en dónde el impacto sobre el esfuerzo respiratorio e intercambio de gases sería fundamental. Con esta racionalidad fisiológica se han desarrollado diversos estudios en diferentes contextos clínicos, esto con el fin de dilucidar cuál terapia es la mejor alternativa. En esta revisión narrativa pretendemos describir y analizar los diversos efectos fisiológicos que induce la VNI y la CNAF
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    Global guidelines, local realities: toward equitable neurocritical care, local data generation and practice patterns in low- and middle-income countries
    (2025) Cordeiro Veiga, Viviane; Chohfi Atallah, Fernanda; Bruhn Cruz, Alejandro Rodrigo; Aryal, Diptesh
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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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    Liquid extracorporeal carbon dioxide removal: Use Of Tham (tris Hydroxymethyl Aminomethane) Coupled To Hemofiltration To Control Hypercapnic Acidosis In A Porcine Model Of Protective Mechanical Ventilation: A Pilot Study
    (2016) Tapia Batalla, Pablo; Lillo, Felipe; Escobar, Leslie; Simón, Felipe; Hernandez, Karina; Alegría, Leyla; Bruhn Cruz, Alejandro Rodrigo
    A promising approach to facilitate protective mechanical ventilation is the use of extracorporeal CO2 removal techniques. Several strategies based on membrane gas exchangers have been developed. However, these techniques are still poorly available. The goal of this study was to assess the efficacy and safety of THAM infusion coupled to hemofiltration for the management of hypercapnic acidosis. A severe respiratory acidosis was induced in seven anesthetized pigs. Five of them were treated with THAM 8-mmol·kg-1·h-1 coupled to hemofiltration (THAM+HF group) at 100 mL·kg-1·h-1. After 18-hours of treatment the THAM infusion was stopped but hemofiltration was kept on until 24-hours. The 2 other animals were treated with THAM but without hemofiltration. After 1-hour of treatment in THAM+HF, PaCO2 rapidly decreased from a median of 89.0 (IQR) (80.0, 98.0) to 71.3 (65.8, 82.0) mmHg (P<0.05), while pH increased from 7.12 (7.01, 7.15) to 7.29 (7.27, 7.30) (P<0.05). Thereafter PaCO2 remained stable between 60-70 mmHg, while pH increased above 7.4. After stopping THAM at 18 hours of treatment a profound rebound effect was observed with severe hypercapnic acidosis. The most important side effect we observed was hyperosmolality, which reached a maximum of 330 (328, 332) mOsm·kg H2O-1 at T18. The animals treated only with THAM developed severe hypercapnia, despite the fact that pH returned to normal values, and died after 12 hours. Control-group had an uneven evolution until the end of the experiment. A combined treatment with THAM coupled to hemofiltration may be an effective treatment to control severe hypercapnic acidosis.
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    Manejo del paciente en shock séptico
    (Ediciones Doyma, S.L., 2011) Bruhn Cruz, Alejandro Rodrigo; Pairumani Medrano, Ronald; Hernández Poblete, Glenn Wilson
    El shock séptico es la manifestación más grave de una infección. Esta se produce como consecuencia de una respuesta inflamatoria sistémica severa que lleva a un colapso cardiovascular y/o microcirculatorio, y a hipoperfusión tisular. La hipoperfusión constituye el elemento central que define la condición de shock y esta debe ser detectada y revertida en forma urgente desde la atención inicial. La evaluación de la perfusión periférica, la diuresis, y la medición del lactato y de la saturación venosa central, son las principales herramientas para evaluar la perfusión sistémica.La reanimación debe comenzar en forma inmediata con la administración agresiva de fluidos, la cual puede ser guiada por parámetros dinámicos de respuesta a fluidos, y continuada hasta normalizar u optimizar las metas de perfusión. En forma paralela se debe iniciar vasopresores en caso de hipotensión marcada, siendo el agente de elección noradrenalina, y conectar precozmente al paciente a ventilación mecánica frente a hipoperfusión severa que no responde a fluidos, o frente a un aumento del trabajo respiratorio. Adicionalmente, el foco infeccioso debe ser tratado agresivamente iniciando antibióticos lo antes posible.
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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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    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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    Physiological effects of high-flow nasal cannula during sustained high-intensity exercise in healthy volunteers: a randomised crossover trial
    (2024) Moya Gallardo, Eduardo Sebastián; García Valdés, Patricio Hernán; Marambio Coloma, Consuelo Belén; Gutiérrez Escobar, Constanza Isidora; Hernández Vargas, Betsabeth Scarlet; Muñoz Castro, Carolina Andrea; Riquelme Sánchez, Santiago Martin; Moo-Millán, Joel; Basoalto Escobar, Roque Ignacio; Bruhn Cruz, Alejandro Rodrigo; Díaz Patino, Orlando Alberto; Damiani Rebolledo, Luis Felipe
    IntroductionHigh-flow nasal cannula (HFNC) has increased exercise capacity in patients with chronic respiratory diseases. However, it remains unknown whether HFNC impacts respiratory physiological variables during exercise. This study aimed to evaluate the effect of HFNC on respiratory physiological variables during sustained high-intensity exercise in healthy volunteers.MethodsWe performed a single-center, open-label, and randomised crossover trial to compare HFNC (60 L·min−1) and Sham-HFNC (2 L·min−1) interventions during a constant work-rate exercise (CWRET) through randomised order. The primary outcome was ΔPes, and the secondary outcomes were other variables of inspiratory effort, ventilation distribution, ventilatory variables, and clinical assessment. We evaluated volunteers at seven-time points (Baseline= T0; CWRET= T1-T2-T3 (minutes: 1′, 4′ and 6′); Cooldown-period= T4-T5-T6 (minutes: 1′; 6′;10′)) in both interventions.ResultsFourteen healthy volunteers (50% women; age: 22 [21–27] years) were enrolled. Mean differences in ΔPes decreased to favor the HFNC intervention compared to Sham-HFNC at T2 (−2.8 cmH2O; 95%CI −5.3 to −0.3), as well as the sPTPmin at T2 (−86.1 cmH2O×s·min−1;95%CI −146.2 to −26.1), and T3 (−79.9 cmH2O×s·min−1;95%CI −142.3 to −17.6). The standard deviation of the regional ventilation delay index was also lower with HFNC compared to Sham-HFNC (T1: −1.38; 95%CI −1.93 to −0.83; T2: −0.71; 95%CI −1.27 to −0.16). There was decreased dyspnea to favor the HFNC, but sPTP-per-breath, spatial distribution ventilation indexes, ventilatory variables, and clinical assessments were nonsignificant between interventions.ConclusionHFNC intervention reduces respiratory effort, dyspnea and improves temporal ventilation distribution in healthy volunteers during CWRET.
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    Preenchendo a lacuna de conhecimento em cuidados intensivos: a importância das publicações de países de baixa e média renda
    (2024) Figueira Salluh, Jorge Ibrain; Maccagnan Pinheiro Besen, Bruno Adler; González-Dambrauskas, Sebastián; Ranjit, Suchitra; Souza, Daniela Carla; Cordeiro Veiga, Viviane; Mer, Mervyn; Bruhn Cruz, Alejandro Rodrigo; Ranzani, Otavio T.; Pisani, Luigi; Aryal, Diptesh; Hashmi, Madiha; Nainan Myatra, Sheila; Carvalho Ferreira, Juliana; Nassar Junior, Antonio Paulo
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    Preenchendo a lacuna de conhecimento em cuidados intensivos: a importância das publicações de países de baixa e média renda
    (2024) Figueira Salluh, Jorge Ibrain; Maccagnan Pinheiro Besen, Bruno Adler; González-Dambrauskas, Sebastián; Ranjit, Suchitra; Souza, Daniela Carla; Cordeiro Veiga, Viviane; Mer, Mervyn; Bruhn Cruz, Alejandro Rodrigo; Ranzani, Otavio T.; Pisani, Luigi; Aryal, Diptesh; Hashmi, Madiha; Nainan Myatra, Sheila; Carvalho Ferreira, Juliana; Nassar Junior, Antonio Paulo
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    Reflections on a Respiratory Therapy Postgraduate Certificate Program in Chile
    (American Thoracic Society, 2024) Kattan Tala, Eduardo José; Basoalto Escobar, Roque Ignacio; Retamal Montes, Jaime Alejandro; Oviedo Álvarez, Vanessa Andrea; Bruhn Cruz, Alejandro Rodrigo; Bugedo Tarraza, Guillermo Jaime
    Chile is a South American country that spans 4,300 km from north to south. Population density and access to critical care are highly concentrated in Santiago’s metropolitan region. After the educational challenges posed by the 2009 H1N1 influenza pandemic, our critical care department at the Pontificia Universidad Catolica de Chile in Santiago created the Respiratory Therapy Postgraduate Certificate as an educational intervention to address the shortage of healthcare professionals with knowledge and skills in performing respiratory support in critically ill patients. Throughout this Perspective, we aim to delineate the program design, major educational results, implementation of educational innovations that allowed us to adapt to the geographical challenges of the country and those imposed by the coronavirus disease (COVID-19) pandemic, and future challenges identified for the next decade.