Browsing by Author "Bruhn, Alejandro"
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- ItemA deep look into the rib cage compression technique in mechanically ventilated patients: a narrative review(2022) Jalil Contreras, Yorschua Frederick; Damiani, L. Felipe; Basoalto, Roque; Bachmman, María Consuelo; Bruhn, AlejandroDefective management of secretions is one of the most frequent complications in invasive mechanically ventilated patients. Clearance of secretions through chest physiotherapy is a critical aspect of the treatment of these patients. Manual rib cage compression is one of the most practiced chest physiotherapy techniques in ventilated patients; however, its impact on clinical outcomes remains controversial due to methodological issues and poor understanding of its action. In this review, we present a detailed analysis of the physical principles involved in rib cage compression technique performance, as well as the physiological effects observed in experimental and clinical studies, which show that the use of brief and vigorous rib cage compression, based on increased expiratory flows (expiratory-inspiratory airflow difference of > 33L/minute), can improve mucus movement toward the glottis. On the other hand, the use of soft and gradual rib cage compression throughout the whole expiratory phase does not impact the expiratory flows, resulting in ineffective or undesired effects in some cases. More physiological studies are needed to understand the principles of the rib cage compression technique in ventilated humans. However, according to the evidence, rib cage compression has more potential benefits than risks, so its implementation should be promoted.
- ItemAirway closure in infants with acute bronchiolitis on mechanical ventilation(2025) Varela Ortiz, Javier; Bruhn, Alejandro; Pontificia Universidad Católica de Chile. Facultad de MedicinaBackground: The pathophysiology of acute bronchiolitis is thought to be explained by the classical mechanism of distal airway obstruction by debris and mucus plugs. However, the alterations in respiratory mechanics described in previous studies suggest that other mechanisms may be involved. Airway closure is a phenomenon mainly characterized by the cyclic collapse of the distal airways, leading to alveolar air trapping, denitrogenation atelectasis, and bronchiolar inflammation. This study aimed to determine whether airway closure is present in patients with severe acute bronchiolitis. Methods: Prospective and observational study in a tertiary-care pediatric intensive care unit at a general hospital in Infants with acute bronchiolitis under mechanical ventilation. We identified the presence of airway closure through a quasistatic pressure-volume curve obtained from a pneumotachometer with a proximal flow sensor. Our findings were corroborated by simultaneously acquiring a pressure-impedance curve and ventilation maps using electrical impedance tomography. Results: Airway closure was confirmed in 7 out of 12 patients with a median airway opening pressure of 14 cmH2O (IQR 11-16). Patients with airway closure exhibited high levels of driving pressure, with a median of 16 cmH2O (IQR 11-17) and low levels of respiratory system compliance, with a median of 0.41 ml/cmH2O/kg (IQR 0.38-0.59). When these parameters were corrected for airway opening pressure, there was a significant decrease in driving pressure, with a median of 9 cmH2O (IQR 9-13), p = 0.027, and a significant increase in respiratory system compliance, with a median of 0.63 ml/cmH2O/kg (IQR 0.51-0.81), p = 0.028. Conclusions: Airway closure is common in ventilated infants with acute bronchiolitis, and its assessment may play a significant role in interpreting respiratory mechanics.
- ItemAirway humidification practices in Chilean intensive care units(SOC MEDICA SANTIAGO, 2012) Retamal, Jaime; Castillo, Juan; Bugedo, Guillermo; Bruhn, AlejandroAirway 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).
- ItemAn evidence-based resuscitation algorithm applied from the emergency room to the ICU improves survival of severe septic shock(2008) Castro López, Ricardo; Regueira Heskia, Tomás; Aguirre Zúniga, Marcia Lorena; Llanos Valdés, Osvaldo Pablo; Bruhn, Alejandro; Bugedo Tarraza, Guillermo; Dougnac Labatut, Alberto; Castillo Fuenzalida, Luis Benito; Andresen Hernández, Max; Hernández P., GlennBackground. Septic shock is highly lethal. We recently implemented an algorithm (advanced resuscitation algorithm for septic shock, ARAS 1) with a global survival of 67%, but with a very high mortality (72%) in severe cases [norepinephrine (NE) requirements >0.3 µg/kg/min for mean arterial pressure ≥70 mmHg]. As new therapies with different levels of evidence were proposed [steroids, drotrecogin alpha, high-volume hemofiltration (HVHF)], we incorporated them according to severity (NE requirements; algorithm ARAS-2), and constructed a multidisciplinary team to manage these patients from the emergency room (ER) to the ICU. The aim of this study was to compare the outcome of severe septic shock patients under both protocols. Methods. Adult patients with severe septic shock were enrolled consecutively and managed prospectively with ARAS1 (1999-2001), and ARAS-2 (2002-05). ARAS-2 incorporates HVHF for intractable shock. Results. Thirty-three patients were managed with each protocol, without statistical differences in baseline demographics, APACHE II (22.2 vs 23.8), SOFA (11.4 vs 12.7) and NE peak levels (0.62 vs 0.8 µg/kg/min). The 28-day mortality and epinephrine use were higher with ARAS-1 (72.7% vs 48.5%; 87.9% vs 18.2 %); and low-dose steroids (35.9% vs 72.7%), drotrecogin (0 vs 15 %) and HVHF use (3.0% vs 39.4%) were higher for ARAS-2 (P<0.05 for all). Conclusion. Management of severe septic shock with a multidisciplinary team and an updated protocol (according to the best current evidence), with precise entry criteria for every intervention at different stages of severity, may improve survival in these patients. Multidisciplinary management, rationalization of the use of vasoactives and rescue therapy based on HVHF instead of epinephrine may have contributed to these results. Management of severe septic shock with these kinds of algorithms is feasible and should be encouraged.
- ItemAssociation 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, JaimeBackground 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.
- ItemCan venous-to-arterial carbon dioxide differences reflect microcirculatory alterations in patients with septic shock?(2016) Arango Dávila, C.; De Backer, D.; Ospina Tascón, Gustavo A. ; Umaña, M.; Bermúdez, W.; Bautista Rincón, D.; Valencia, J.; Madriñán, H.; Hernández P., Glenn; Bruhn, Alejandro
- ItemCateterización venosa suprahepática en cuatro casos de shock séptico severo(2001) Inzunza Pérez, Carlos; Cornu A., M.; Bruhn, Alejandro; Castillo Fuenzalida, Luis Benito; Bugedo Tarraza, Guillermo; Acuña C., D.; Medeiros U., S.; Hernández P., Glenn
- ItemChallenges and limitations of using ventilator-free days as an outcome in critical care trials(2024) Bruhn, Alejandro; Kattan Tala, Eduardo José; Biasi Cavalcanti, Alexandre
- ItemClinical characteristics, systemic complications, and in-hospital outcomes for patients with COVID-19 in Latin America. LIVEN-Covid-19 study: A prospective, multicenter, multinational, cohort study(PUBLIC LIBRARY SCIENCE, 2022) Reyes, Luis F.; Bastidas, Alirio; Narvaez, Paula O.; Parra-Tanoux, Daniela; Fuentes, Yuli, V; Serrano-Mayorga, Cristian C.; Ortiz, Valentina; Caceres, Eder L.; Ospina Tascón, Gustavo A.; Diaz, Ana M.; Jibaja, Manuel; Vera, Magdalena; Silva, Edwin; Gorordo-Delsol, Luis Antonio; Maraschin, Francesca; Varon-Vega, Fabio; Buitrago, Ricardo; Poveda, Marcela; Saucedo, Lina M.; Estenssoro, Elisa; Ortiz, Guillermo; Nin, Nicolas; Calderon, Luis E.; Montano, Gina S.; Chaar, Aldair J.; Garcia, Fernanda; Ramirez, Vanessa; Picoita, Fabricio; Pelaez, Cristian; Unigarro, Luis; Friedman, Gilberto; Cucunubo, Laura; Bruhn, Alejandro; Hernandez, Glenn; Martin-Loeches, IgnacioPurpose
- ItemCombination of arterial lactate levels and venous-arterial CO2 to arterial-venous O-2 content difference ratio as markers of resuscitation in patients with septic shock(2015) Ospina Tascón, Gustavo A.; Umana, Mauricio; Bermudez, William; Bautista-Rincon, Diego F.; Hernández P., Glenn; Bruhn, Alejandro; Granados, Marcela; Salazar, Blanca; Arango-Dávila, César; De Backer, Daniel
- ItemContinuous prolonged prone positioning in COVID-19-related ARDS: a multicenter cohort study from Chile(2022) Cornejo, Rodrigo A.; Montoya, Jorge; Gajardo, Abraham I. J.; Graf, Jerónimo; Alegría Vargas, Leyla; Baghetti, Romyna; Irarrázaval, Anita; Santis, César; Pavez, Nicolás; Leighton, Sofía; Tomicic, Vinko; Morales, Daniel; Ruiz Balart, Carolina; Navarrete, Pablo; Vargas, Patricio; Gálvez, Roberto; Espinosa, Victoria; Lazo, Marioli; Pérez-Araos, Rodrigo A.; Garay, Osvaldo; Sepúlveda, Patrick; Martinez, Edgardo; Bruhn, Alejandro; The SOCHIMI Prone-COVID-19 Group; Pontificia Universidad Católica de Chile. Escuela de MedicinaBackground Prone positioning is currently applied in time-limited daily sessions up to 24 h which determines that most patients require several sessions. Although longer prone sessions have been reported, there is scarce evidence about the feasibility and safety of such approach. We analyzed feasibility and safety of a continuous prolonged prone positioning strategy implemented nationwide, in a large cohort of COVID-19 patients in Chile. Methods: Retrospective cohort study of mechanically ventilated COVID-19 patients with moderate-to-severe acute respiratory distress syndrome (ARDS), conducted in 15 Intensive Care Units, which adhered to a national protocol of continuous prone sessions ≥ 48 h and until PaO2:FiO2 increased above 200 mm Hg. The number and extension of prone sessions were registered, along with relevant physiologic data and adverse events related to prone positioning. The cohort was stratified according to the first prone session duration: Group A, 2–3 days; Group B, 4–5 days; and Group C, > 5 days. Multivariable regression analyses were performed to assess whether the duration of prone sessions could impact safety. Results: We included 417 patients who required a first prone session of 4 (3–5) days of whom 318 (76.3%) received only one session. During the first prone session the main adverse event was grade 1–2 pressure sores in 97 (23.9%) patients; severe adverse events were infrequent with 17 non-scheduled extubations (4.2%). 90-day mortality was 36.2%. Ninety-eight patients (24%) were classified as group C; they exhibited a more severe ARDS at baseline, as reflected by lower PaO2:FiO2 ratio and higher ventilatory ratio, and had a higher rate of pressure sores (44%) and higher 90-day mortality (48%). However, after adjustment for severity and several relevant confounders, prone session duration was not associated with mortality or pressure sores. Conclusions: Nationwide implementation of a continuous prolonged prone positioning strategy for COVID-19 ARDS patients was feasible. Minor pressure sores were frequent but within the ranges previously described, while severe adverse events were infrequent. The duration of prone session did not have an adverse effect on safety.
- ItemDevelopment of mechanical ventilators in Chile. Chronicle of the initiative "Un Respiro para Chile(2022) Bugedo, Guillermo; Tobar, Eduardo; Alegria, Leyla; Oviedo, Vanessa; Arellano, Daniel; Basoalto, Roque; Enberg, Luis; Suarez, Pablo; Bitran, Eduardo; Chabert, Steren; Bruhn, AlejandroAt the beginning of the COVID-19 pandemic in Chile, in March 2020, a projection indicated that a significant group of patients with pneumonia would require admission to an Intensive Care Unit and connection to a mechanical ventilator. Therefore, a paucity of these devices and other supplies was predicted. The initiative "Un respiro para Chile" brought together many people and institutions, public and private. In the course of three months, it allowed the design and building of several ventilatory assistance devices, which could be used in critically ill patients.
- ItemDexmedetomidine ameliorates gut lactate production and impairment of exogenous lactate clearance in an endotoxic sheep model(2015) Hernández P., Glenn; Tapia, Pablo; Bruhn, Alejandro; Soto, Dagoberto; Alegría, Leyla; Jarufe Cassis, Nicolás; Menchaca, Rodrigo; Meissner, Arturo; Vives, María Ignacia; Ospina Tascón, Gustavo A.; Luengo, Cecilia; Bakker, Jan
- ItemDoes Regional Lung Strain Correlate With Regional Inflammation in Acute Respiratory Distress Syndrome During Nonprotective Ventilation? An Experimental Porcine Study(2018) Retamal Montes, Jaime; Hurtado Sepúlveda, Daniel; Villarroel, Nicolás; Bruhn, Alejandro; Bugedo Tarraza, Guillermo; Amato, Marcelo; Costa, Eduardo L. V.; Hedenstierna, Goran; Larsson, Anders; Borges, Joäo Batista
- ItemDoes the use of high PEEP levels prevent ventilator-induced lung injury?(2017) Bugedo Tarraza, Guillermo; Retamal Montes, Jaime; Bruhn, Alejandro
- ItemDouble cycling with breath-stacking during partial support ventilation in ARDS: Just a feature of natural variability?(2025) Brito, Roberto; Morais, Caio C. A.; Arellano, Daniel H.; Gajardo, Abraham I. J.; Bruhn, Alejandro; Brochard, L.; Amato, Marcelo B. P.; Cornejo, Rodrigo A.Background Double cycling with breath-stacking (DC/BS) during controlled mechanical ventilation is considered potentially injurious, reflecting a high respiratory drive. During partial ventilatory support, its occurrence might be attributable to physiological variability of breathing patterns, reflecting the response of the mode without carrying specific risks. Methods This secondary analysis of a crossover study evaluated DC/BS events in hypoxemic patients resuming spontaneous breathing in cross-over under neurally adjusted ventilatory assist (NAVA), proportional assist ventilation (PAV +), and pressure support ventilation (PSV). DC/BS was defined as two inspiratory cycles with incomplete exhalation. Measurements included electrical impedance signal, airway pressure, esophageal and gastric pressures, and flow. Breathing variability, dynamic compliance (CLdyn), and end-expiratory lung impedance (EELI) were analyzed. Results Twenty patients under assisted breathing, with a median of 9 [5–14] days on mechanical ventilation, were included. DC/BS was attributed to either a single (42%) or two apparent consecutive inspiratory efforts (58%). The median [IQR] incidence of DC/BS was low: 0.6 [0.1–2.6] % in NAVA, 0.0 [0.0–0.4] % in PAV + , and 0.1 [0.0–0.4] % in PSV (p = 0.06). DC/BS events were associated with patient’s coefficient of variability for tidal volume (p = 0.014) and respiratory rate (p = 0.011). DC/BS breaths exhibited higher tidal volume, muscular pressure and regional stretch compared to regular breaths. Post-DC/BS cycles frequently exhibited improved EELI and CLdyn, with no evidence of expiratory muscle activation in 63% of cases. Conclusions DC/BS events during partial ventilatory support were infrequent and linked to breathing variability. Their frequency and physiological effects on lung compliance and EELI resemble spontaneous sighs and may not be considered a priori as harmful.
- ItemDriving pressure : a marker of severity, a safety limit, or a goal for mechanical ventilation?(2017) Bugedo Tarraza, Guillermo; Retamal Montes, Jaime; Bruhn, Alejandro
- ItemEarly and severe impairment of lactate clearance in endotoxic shock is not related to liver hypoperfusion: preliminary report(2014) Tapia, Pablo; Soto, Dagoberto; Bruhn, Alejandro; Regueira Heskia, Tomás; Jarufe Cassis, Nicolás; Alegría, Leyla; Bachler, J. P.; Leon, F.; Vicuña, C.; Hernández P., Glenn
- ItemEffect of a lung rest strategy during ECMO in a porcine acute lung injury model(2015) Araos, J.; Tapia, Pablo; Alegría, Leyla; García Cañete, Patricia; Rodríguez, F.; Amthauer, M.; Castro, G.; Soto, Dagoberto; Damiani Rebolledo, L. Felipe; Bugedo Tarraza, Guillermo; Bruhn, Alejandro; Cruces, Pablo; Salomon, Tatiana; Erranz, B.; Carreño, P.; Medina, T.
- ItemEffect 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, GuillermoBackground 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)