Browsing by Author "Ruiz-Rudolph, Pablo"
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- ItemPendelluft 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.
- ItemPhysiological effects of high-flow nasal cannula oxygen therapy after extubation: a randomized crossover study(2023) Basoalto Escobar, Roque Ignacio; Damiani Rebolledo, L. Felipe; Jalil, Yorschua; Bachmann, María Consuelo; Oviedo, Vanessa; Alegría Vargas, Leyla; Valenzuela, Emilio Daniel; Rovegno Echavarria, Maxiliano; Ruiz-Rudolph, Pablo; Cornejo, Rodrigo; Retamal Montes, Jaime; Bugedo Tarraza, Guillermo; Thille, Arnaud W.; Bruhn, AlejandroAbstract: Background: Prophylactic high-flow nasal cannula (HFNC) oxygen therapy can decrease the risk of extubation failure. It is frequently used in the postextubation phase alone or in combination with noninvasive ventilation. However, its physiological effects in this setting have not been thoroughly investigated. The aim of this study was to determine comprehensively the effects of HFNC applied after extubation on respiratory effort, diaphragm activity, gas exchange, ventilation distribution, and cardiovascular biomarkers. Methods: This was a prospective randomized crossover physiological study in critically ill patients comparing 1 h of HFNC versus 1 h of standard oxygen after extubation. The main inclusion criteria were mechanical ventilation for at least 48 h due to acute respiratory failure, and extubation after a successful spontaneous breathing trial (SBT). We measured respiratory effort through esophageal/transdiaphragmatic pressures, and diaphragm electrical activity (ΔEAdi). Lung volumes and ventilation distribution were estimated by electrical impedance tomography. Arterial and central venous blood gases were analyzed, as well as cardiac stress biomarkers. Results: We enrolled 22 patients (age 59 ± 17 years; 9 women) who had been intubated for 8 ± 6 days before extubation. Respiratory effort was significantly lower with HFNC than with standard oxygen therapy, as evidenced by esophageal pressure swings (5.3 [4.2–7.1] vs. 7.2 [5.6–10.3] cmH2O; p < 0.001), pressure–time product (85 [67–140] vs. 156 [114–238] cmH2O*s/min; p < 0.001) and ΔEAdi (10 [7–13] vs. 14 [9–16] µV; p = 0.022). In addition, HFNC induced increases in end-expiratory lung volume and PaO2/FiO2 ratio, decreases in respiratory rate and ventilatory ratio, while no changes were observed in systemic hemodynamics, Troponin T, or in amino-terminal pro-B-type natriuretic peptide. Conclusions: Prophylactic application of HFNC after extubation provides substantial respiratory support and unloads respiratory muscles.