Browsing by Author "Oviedo Álvarez, Vanessa Andrea"

Now showing 1 - 4 of 4
  • Thumbnail Image
    Item
    Association between controlled mechanical ventilation and systemic inflammation in acute hypoxemic respiratory failure: an observational cohort study
    (2025) Bachmann Barrón, María Consuelo; Benites, Martín H.; Oviedo Álvarez, Vanessa Andrea; Hamidi Vadeghani, Majd Niki; Soto Muñoz, Dagoberto Igor; Basoalto Escobar, Roque Ignacio; Cruces, Pablo; Jalil Contreras, Yorschua Frederick; Damiani Rebolledo, L. Felipe; Bugedo Tarraza, Guillermo; Bruhn, Alejandro; Retamal Montes, Jaime
    Background In patients with acute hypoxemic respiratory failure, spontaneous breathing efforts may contribute to patient self-inflicted lung injury through increased ventilation inhomogeneity and systemic inflammation. Whether early transition to controlled mechanical ventilation (CMV) mitigates these effects remains uncertain. Methods This observational, prospective cohort study included 40 ICU patients with acute hypoxemic respiratory failure who initially breathed spontaneously. Based on clinical decisions, patients were managed with either continued spontaneous breathing (SB group, n = 12) or transitioned to CMV (CMV group, n = 28). Arterial blood gases, hemodynamics, plasma cytokines (IL-6 and IL-8), and ventilation distribution via electrical impedance tomography (EIT) were recorded at baseline and after 24 h. In the CMV group, intermediate time points (T2, T6, T12) were also assessed after intubation. The trial was registered in ClinicalTrials.gov (NCT03513809). Results In the CMV group, respiratory rate and heart rate decreased significantly over time. IL-6 levels dropped markedly from 305 ± 938 pg/mL at baseline to 27 ± 58 pg/mL at 24 h (p = 0.0195), accompanied by a significant improvement in oxygenation (PaO₂/FiO₂ from 140 ± 51 to 199 ± 67, p = 0.0004). EIT data showed improved ventilation distribution with increased end-expiratory lung impedance, decreased global inhomogeneity, and a shift in the center of ventilation toward dorsal regions. In contrast, the SB group showed no significant changes over 24 h in gas exchange, systemic inflammation, or EIT-derived parameters. Conclusions In patients with acute hypoxemic respiratory failure initially breathing spontaneously, transition to CMV was associated with reduced IL-6 levels and improved ventilatory homogeneity over 24 h. These exploratory findings indicate that connection to controlled mechanical ventilation was associated with reduced systemic inflammation, a relationship that warrants confirmation in larger prospective studies.
  • Thumbnail Image
    Item
    Effect of decreasing respiratory rate on the mechanical power of ventilation and lung injury biomarkers: a randomized cross-over clinical study in COVID-19 ARDS patients
    (Springer Nature, 2025) Damiani Rebolledo, L. Felipe; Basoalto Escobar, Roque Ignacio; Oviedo Álvarez, Vanessa Andrea; Alegría Vargas, Leyla; Soto Muñoz, Dagoberto Igor; Bachmann Barrón, María Consuelo; Jalil Contreras, Yorschua Frederick; Santis Fuentes, César Antonio; Carpio Cordero, David Bernardo; Ulloa Morrison, Rodrigo; Valenzuela Espinoza, Emilio Daniel; Vera Alarcón, María Magdalena; Schultz, Marcus J.; Retamal Montes, Jaime; Bruhn, Alejandro; Bugedo Tarraza, Guillermo
    Background The respiratory rate (RR) is a key determinant of the mechanical power of ventilation (MP). The effect of reducing the RR on MP and its potential to mitigate ventilator-induced lung injury remains unclear. Objectives To compare invasive ventilation using a lower versus a higher RR with respect to MP and plasma biomarkers of lung injury in COVID-19 ARDS patients. Methods In a randomized cross-over clinical study in COVID-19 ARDS patients, we compared ventilation using a lower versus a higher RR in time blocks of 12 h. Patients were ventilated with tidal volumes of 6 ml/kg predicted body weight, and positive-end-expiratory pressure and fraction of inspired oxygen according to an ARDS network table. Respiratory mechanics and hemodynamics were assessed at the end of each period, and blood samples were drawn for measurements of inflammatory cytokines, epithelial and endothelial lung injury markers. In a subgroup of patients, we performed echocardiography and esophageal pressure measurements. Results We enrolled a total of 32 patients (26 males [81%], aged 52 [44–64] years). The median respiratory rate during ventilation with a lower and a higher RR was 20 [16–22] vs. 30 [26–32] breaths/min (p < 0.001), associated with a lower median minute ventilation (7.3 [6.5–8.5] vs. 11.6 [10–13] L/min [p < 0.001]) and a lower median MP (15 [11–18] vs. 25 [21–32] J/min [p < 0.001]). No differences were observed in any inflammatory (IL-6, IL-8, and TNF-R1), epithelial (s-RAGE and SP-D), endothelial (Angiopoietin-2), or pro-fibrotic activity (TGF-ß) marker between high or low RR. Cardiac function by echocardiography, and respiratory mechanics using esophageal pressure measurements were also not different. Conclusions Reducing the respiratory rate decreases mechanical power in COVID-19 ARDS patients but does not reduce plasma lung injury biomarkers levels in this cross-over study. Study registration This study is registered at clinicaltrials.gov (study identifier NCT04641897)
  • No Thumbnail Available
    Item
    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.
  • No Thumbnail Available
    Item
    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.