Browsing by Author "Damiani Rebolledo, L. Felipe"

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    Automated detection and quantification of reverse triggering effort under mechanical ventilation
    (2021) Pham, Tài; Montanya, Jaume; Telias, Irene; Piraino, Thomas; Magrans, Rudys; Coudroy, Rémi; Damiani Rebolledo, L. Felipe; Mellado Artigas, Ricard; Madorno, Matías; Blanch, Lluis
    Abstract Background Reverse triggering (RT) is a dyssynchrony defined by a respiratory muscle contraction following a passive mechanical insufflation. It is potentially harmful for the lung and the diaphragm, but its detection is challenging. Magnitude of effort generated by RT is currently unknown. Our objective was to validate supervised methods for automatic detection of RT using only airway pressure (Paw) and flow. A secondary objective was to describe the magnitude of the efforts generated during RT. Methods We developed algorithms for detection of RT using Paw and flow waveforms. Experts having Paw, flow and esophageal pressure (Pes) assessed automatic detection accuracy by comparison against visual assessment. Muscular pressure (Pmus) was measured from Pes during RT, triggered breaths and ineffective efforts. Results Tracings from 20 hypoxemic patients were used (mean age 65 ± 12 years, 65% male, ICU survival 75%). RT was present in 24% of the breaths ranging from 0 (patients paralyzed or in pressure support ventilation) to 93.3%. Automatic detection accuracy was 95.5%: sensitivity 83.1%, specificity 99.4%, positive predictive value 97.6%, negative predictive value 95.0% and kappa index of 0.87. Pmus of RT ranged from 1.3 to 36.8 cmH20, with a median of 8.7 cmH20. RT with breath stacking had the highest levels of Pmus, and RTs with no breath stacking were of similar magnitude than pressure support breaths. Conclusion An automated detection tool using airway pressure and flow can diagnose reverse triggering with excellent accuracy. RT generates a median Pmus of 9 cmH2O with important variability between and within patients. Trial registration BEARDS, NCT03447288.
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    Duration of diaphragmatic inactivity after endotracheal intubation of critically ill patients
    (2021) Sklar, Michael Chaim; Damiani Rebolledo, L. Felipe; Madotto, Fabiana; Jonkman, Annemijn; Rauseo, Michela; Soliman, Ibrahim; Telias, Irene; Dubo, Sebastian; Chen, Lu; Rittayamai, Nuttapol
    Abstract Background In patients intubated for mechanical ventilation, prolonged diaphragm inactivity could lead to weakness and poor outcome. Time to resume a minimal diaphragm activity may be related to sedation practice and patient severity. Methods Prospective observational study in critically ill patients. Diaphragm electrical activity (EAdi) was continuously recorded after intubation looking for resumption of a minimal level of diaphragm activity (beginning of the first 24 h period with median EAdi > 7 µV, a threshold based on literature and correlations with diaphragm thickening fraction). Recordings were collected until full spontaneous breathing, extubation, death or 120 h. A 1 h waveform recording was collected daily to identify reverse triggering. Results Seventy-five patients were enrolled and 69 analyzed (mean age ± standard deviation 63 ± 16 years). Reasons for ventilation were respiratory (55%), hemodynamic (19%) and neurologic (20%). Eight catheter disconnections occurred. The median time for resumption of EAdi was 22 h (interquartile range 0–50 h); 35/69 (51%) of patients resumed activity within 24 h while 4 had no recovery after 5 days. Late recovery was associated with use of sedative agents, cumulative doses of propofol and fentanyl, controlled ventilation and age (older patients receiving less sedation). Severity of illness, oxygenation, renal and hepatic function, reason for intubation were not associated with EAdi resumption. At least 20% of patients initiated EAdi with reverse triggering. Conclusion Low levels of diaphragm electrical activity are common in the early course of mechanical ventilation: 50% of patients do not recover diaphragmatic activity within one day. Sedatives are the main factors accounting for this delay independently from lung or general severity. Trial Registration ClinicalTrials.gov (NCT02434016). Registered on April 27, 2015. First patients enrolled June 2015.
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    Eccentric Contractions of the Diaphragm During Mechanical Ventilation
    (2023) García Valdés, Patricio Hernán; Fernandez Mincone, Tiziana Rita; Jalil Contreras, Yorschua Frederick; Peñailillo, Luis; Damiani Rebolledo, L. Felipe
    Diaphragm dysfunction is a highly prevalent phenomenon in patients receiving mechanical ventilation, mainly due to ventilatory over-assistance and the development of diaphragm disuse atrophy. Promoting diaphragm activation whenever possible and facilitating an adequate interaction between the patient and the ventilator is encouraged at the bedside to avoid myotrauma and further lung injury. Eccentric contractions of the diaphragm are defined as muscle activation while muscle fibers are lengthening within the exhalation phase. There is recent evidence that suggests that eccentric activation of the diaphragm is very frequent and may occur during post-inspiratory activity or under different types of patient-ventilator asynchronies, which include ineffective efforts, premature cycling, and reverse triggering. The consequences of this eccentric contraction of the diaphragm may have opposite effects, depending on the level of breathing effort. For instance, during high or excessive effort, eccentric contractions can result in diaphragm dysfunction and injured muscle fibers. Conversely, when eccentric contractions of the diaphragm occur along with low breathing effort, a preserved diaphragm function, better oxygenation, and more aerated lung tissue are observed. Despite this controversial evidence, evaluating the level of breathing effort at the bedside seems crucial and is highly recommended to optimize ventilatory therapy. The impact of eccentric contractions of the diaphragm on the patient's outcome remains to be elucidated.
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    Effect 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.
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    Extracorporeal membrane oxygenation improves survival in a novel 24-hour pig model of severe acute respiratory distress syndrome
    (2016) Araos, J.; Alegría Aguirre, Luz Katiushka; Garcia, P.; Damiani Rebolledo, L. Felipe; Tapia, P.; Soto, D.; Salomon, T.; Retamal Montes, Jaime; Bugedo Tarraza, Guillermo; Bruhn, Alejandro; Rodriguez, F.; Amthauer, M.; Erranz, B.; Castro, G.; Carreno, P.; Medina, T.; Cruces, P.
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    Geographic latitude and sleep duration: A population-based survey from the Tropic of Capricorn to the Antarctic Circle
    (2017) Brockmann Veloso, Pablo Edmundo; Gozal, D.; Villarroel del Pino, Luis A.; Damiani Rebolledo, L. Felipe; Nunez, F.; Cajochen, C.
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    Impact of a Noninvasive Ventilation Protocol in Hospitalized Children With Acute Respiratory Failure
    (2017) Jalil Contreras, Yorschua Frederick; Damiani Rebolledo, L. Felipe; Astudillo, C.; Villarroel S, G.; Barañao Garcés, Patricio; Bustos, E.; Silva, A.; Méndez Lesser, Manuel
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    Impact of Awake Prone Positioning on Inspiratory Effort and Work of Breathing. A Physiological Study in Healthy Subjects
    (American Thoracic Society, 2022) Damiani Rebolledo, L. Felipe; Basoalto Escobar, Roque Ignacio; Bachmann Barrón, María Consuelo; Jalil Contreras, Yorschua Frederick; Acuña, V.; Díaz, G.; Mella, J.; García Valdés, Patricio Hernán; Moya Gallardo, Eduardo Sebastián; Villarroel, G.; Retamal Montes, Jaime; Bugedo Tarraza, Guillermo; Bruhn, Alejandro
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    Impact of television on the quality of sleep in preschool children
    (2016) Brockmann Veloso, Pablo Edmundo; Diaz, B.; Damiani Rebolledo, L. Felipe; Villarroel del Pino, Luis A.; Nuñez, F.; Bruni, O.
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    Long-term effects of adenotonsillectomy in children with obstructive sleep apnoea : protocol for a systematic review
    (2016) Damiani Rebolledo, L. Felipe; Rada G., Gabriel; Gana Ansaldo, Juan Cristóbal; Brockmann Veloso, Pablo Edmundo; Alberti, Gigliola
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    Low Spontaneous Breathing Effort during Extracorporeal Membrane Oxygenation in a Porcine Model of Severe Acute Respiratory Distress Syndrome
    (2020) Dubo, S.; Oviedo, V.; Garcia, A.; Alegría Aguirre, Luz Katiushka; Garcia, P.; Valenzuela, E. D.; Damiani Rebolledo, L. Felipe; Araos, J.; Medina, T.; Retamal Montes, Jaime; Bachmann, M. C.; Basoalto, R.; Bravo, S.; Soto, D.; Cruces, P.; Guzman, P.; Cornejo, R.; Bugedo Tarraza, Guillermo; Brebi, P.; Bruhn, Alejandro
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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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    Metabolic consequences of snoring in adolescents and younger adults : a population study in Chile
    (2016) Brockmann Veloso, Pablo Edmundo; Damiani Rebolledo, L. Felipe; Smith, D.; Castet, A.; Nunez, F.; Villarroel del Pino, Luis A.; Gozal, D.
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    Near-apneic ventilation decreases lung injury and fibroproliferation in an acute respiratory distress syndrome model with extracorporeal membrane oxygenation
    (2019) Araos, J.; Alegría Aguirre, Luz Katiushka; Garcia, P.; Cruces, P.; Soto, D.; Erranz, B.; Amthauer, M.; Ayala, Pedro; Borzone, Gisella; Damiani Rebolledo, L. Felipe
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    Physiological 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, Alejandro
    Abstract: 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.
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    Physiological effects of high-flow nasal cannula oxygen therapy after extubation: a randomized crossover study
    (Springer Open, 2023) Basoalto Escobar, Roque Ignacio; Damiani Rebolledo, L. Felipe; Jalil Contreras, Yorschua Frederick; Bachmann Barrón, Maria Consuelo; Oviedo, Vanessa; Alegria Vargas, Leyla; Valenzuela Espinoza Emilio Daniel; Rovegno Echavarria, David Maximiliano; Ruiz-Rudolph, Pablo; Cornejo, Rodrigo; Retamal Montes, Jaime; Bugedo Tarraza, Guillermo; Thille, Arnaud W.; Bruhn, Alejandro
    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. Trial registration January 15, 2021. NCT04711759.
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    Post-insufflation diaphragm contractions in patients receiving various modes of mechanical ventilation
    (2024) Rodrigues, Antenor; Vieira, Fernando; Sklar, Michael Chaim; Damiani Rebolledo, L. Felipe; Piraino, Thomas; Telias, Irene; Goligher, Ewan C.; Reid, W. Darlene; Brochard, Laurent
    Background: During mechanical ventilation, post-insufflation diaphragm contractions (PIDCs) are non-physiologic and could be injurious. PIDCs could be frequent during reverse-triggering, where diaphragm contractions follow the ventilator rhythm. Whether PIDCs happens with different modes of assisted ventilation is unknown. In mechanically ventilated patients with hypoxemic respiratory failure, we aimed to examine whether PIDCs are associated with ventilator settings, patients’ characteristics or both. Methods: One-hour recordings of diaphragm electromyography (EAdi), airway pressure and flow were collected once per day for up to five days from intubation until full recovery of diaphragm activity or death. Each breath was classified as mandatory (without-reverse-triggering), reverse-triggering, or patient triggered. Reverse triggering was further subclassified according to EAdi timing relative to ventilator cycle or reverse triggering leading to breath-stacking. EAdi timing (onset, offset), peak and neural inspiratory time (Tineuro) were measured breath-by-breath and compared to the ventilator expiratory time. A multivariable logistic regression model was used to investigate factors independently associated with PIDCs, including EAdi timing, amplitude, Tineuro, ventilator settings and APACHE II. Results: Forty-seven patients (median[25%-75%IQR] age: 63[52–77] years, BMI: 24.9[22.9–33.7] kg/m2, 49% male, APACHE II: 21[19–28]) contributed 2 ± 1 recordings each, totaling 183,962 breaths. PIDCs occurred in 74% of reverse-triggering, 27% of pressure support breaths, 21% of assist-control breaths, 5% of Neurally Adjusted Ventilatory Assist (NAVA) breaths. PIDCs were associated with higher EAdi peak (odds ratio [OR][95%CI] 1.01[1.01;1.01], longer Tineuro (OR 37.59[34.50;40.98]), shorter ventilator inspiratory time (OR 0.27[0.24;0.30]), high peak inspiratory flow (OR 0.22[0.20;0.26]), and small tidal volumes (OR 0.31[0.25;0.37]) (all P ≤ 0.008). NAVA was associated with absence of PIDCs (OR 0.03[0.02;0.03]; P < 0.001). Reverse triggering was characterized by lower EAdi peak than breaths triggered under pressure support and associated with small tidal volume and shorter set inspiratory time than breaths triggered under assist-control (all P < 0.05). Reverse triggering leading to breath stacking was characterized by higher peak EAdi and longer Tineuro and associated with small tidal volumes compared to all other reverse-triggering phenotypes (all P < 0.05). Conclusions: In critically ill mechanically ventilated patients, PIDCs and reverse triggering phenotypes were associated with potentially modifiable factors, including ventilator settings. Proportional modes like NAVA represent a solution abolishing PIDCs.
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    Reverse triggering ? a novel or previously missed phenomenon?
    (2024) Jackson, Robert; Kim, Audery; Moroz, Nikolay; Damiani Rebolledo, L. Felipe; Luca Grieco, Domenico; Piraino, Thomas; Friedrich, Jan O.; Mercat, Alain; Telias, Irene; Brochard, Laurent J.
    Background Reverse triggering (RT) was described in 2013 as a form of patient-ventilator asynchrony, where patient’s respiratory effort follows mechanical insufflation. Diagnosis requires esophageal pressure (Pes) or diaphragmatic electrical activity (EAdi), but RT can also be diagnosed using standard ventilator waveforms. Hypothesis We wondered (1) how frequently RT would be present but undetected in the figures from literature, especially before 2013; (2) whether it would be more prevalent in the era of small tidal volumes after 2000. Methods We searched PubMed, EMBASE, and the Cochrane Central Register of Controlled Trials, from 1950 to 2017, with key words related to asynchrony to identify papers with figures including ventilator waveforms expected to display RT if present. Experts labelled waveforms. ‘Definite’ RT was identified when Pes or EAdi were in the tracing, and ‘possible’ RT when only flow and pressure waveforms were present. Expert assessment was compared to the author’s descriptions of waveforms. Results We found 65 appropriate papers published from 1977 to now, containing 181 ventilator waveforms. 21 cases of ‘possible’ RT and 25 cases of ‘definite’ RT were identified by the experts. 18.8% of waveforms prior to 2013 had evidence of RT. Most cases were published after 2000 (1 before vs. 45 after, p=0.03). 54% of RT cases were attributed to different phenomena. A few cases of identified RT were already described prior to 2013 using different terminology (earliest in 1997). While RT cases attributed to different phenomena decreased after 2013, 60% of ‘possible’ RT remained missed. RT has been present in the literature as early as 1997, but most cases were found after the introduction of low tidal volume ventilation in 2000. Following 2013, the number of undetected cases decreased, but RT are still commonly missed
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    Reverse triggering dyssynchrony and its impact on diaphragm injury during mechanical ventilation.
    (2020) Damiani Rebolledo, L. Felipe; Bruhn, Alejandro; Brochard, Laurent; Pontificia Universidad Católica de Chile. Escuela de Medicina
    Mechanical ventilation (MV) is used to sustain life in patients admitted to the intensive care unit for a wide spectrum of indications such as elective surgical procedures, septic shock, multiple organic failure and acute respiratory distress syndrome. Safe and effective ventilation depends on a smooth interaction between these two independent systems: the patient and the mechanical ventilator. Any mismatch between the patient and mechanical ventilator in terms of breath delivery timing, as well as the inability of the ventilator’s flow delivery to match the patient’s flow demand, is referred to as patient-ventilator dyssynchrony (PVD). Reverse Triggering (RT) is a type of PVD where muscle contractions are delayed, starting a certain amount of time after the machine triggered breath and occurring under different entrainment patterns. RT was originally described in 2013, in sedated patients admitted to the intensive care unit. Unfortunately, data about RT until now is scarce and its relevance remains totally uncertain. If any, the relevance of RT might be attributed to 2 main factors: the frequency of this PVD and its potential consequences in both lung and diaphragm injury. The group of different adverse patient–ventilator interactions leading to diaphragm atrophy and injury and resulting in a final common pathway of diaphragm weakness are denominated myotrauma. Particularly, RT is thought to cause eccentric myotrauma, which is a muscle contraction while muscle is lengthening during the ventilator’s expiratory phase while lung volume is decreasing. Based on animal and human studies, the impact of RT (if any) might be mediated by the level of breathing effort. In this thesis we aimed to describe the incidence of RT in patients early after intubation and admission to the intensive care unit and also to study the impact of RT with different levels of breathing effort on diaphragm injury (function and structure) in an animal model of RT with acute respiratory distress syndrome. To determine RT incidence, we conducted ancillary study in patients with continuous monitorization of the electrical activity of the diaphragm (EAdi). We developed a method for automatic detection of reverse triggering using EAdi and airway pressure curve. We additionally compared patients’ demographics, sedation depth and ventilation settings according to the median rate of reverse triggering, including time to transition to assisted ventilation or extubation. We found that our new automatic method presented a good diagnostic accuracy (98% total accuracy). Using a threshold of 1 µV for EAdi, median reverse triggering rate was 8% (range 0.1 to 75) with 44% (17 out of 39) of patients having ≥10% of breaths with reverse triggering. With 3 µV threshold, 26% (10 out of 39) of patients had ≥10% reverse triggered breaths. Importantly, patients who resented more reverse triggering were more likely to be on an assisted mode or extubated in the following 24 hours than patients who had low rate of RT (68% vs 35%; p=0.039). We also developed a 3 hours model of reverse triggering in pigs by modifying tidal volume, respiratory rate and level of sedation. Our approach to induce reverse triggering was not only feasible, but consistently reproducible in all animals, although with different presentations in terms of breathing effort and entrainment pattern. The most frequent entrainment pattern observed was 1:1, occurring in 83% of the total animals. Compared to passive ventilation (no breathing effort), RT group had significantly lower tidal volume (7 vs 10 ml/kg) and higher respiratory rate (45 vs 31 bpm) whereas no differences were found in other cardiorespiratory and sedation variables, nor in lung injury indicators after the study period. In order to study the impact of RT on diaphragm injury, we divided the RT group in 3 subgroups based on the level of breathing effort calculated by the pressure time product. Thus, 4 experimental groups were analyzed: Passive (no breathing effort), RT with low effort, RT with middle effort and RT with high effort. Function of the diaphragm was assessed by the ability to generate force, which correspond to the transdiaphragmatic pressure whilst diaphragm structure was evaluated using histological samples and serum troponin I as biomarker of muscle injury. We found that RT affects diaphragm function in two opposite directions. On one hand, animals with RT and low breathing effort showed a significant increase in force of 10% as compared to baseline. On the other hand, animals with RT and high breathing effort showed a larger decrease in force (34%) as compared to baseline. This difference was significantly different with the other experimental groups. Moreover, histologic analysis of diaphragm myofibers showed that RT with high breathing effort had significant lower myofiber cross-sectional area than passive group. Also, when comparing abnormal myofibers between groups, a significantly lower proportion of small fiber size were found in RT whit high breathing effort in comparison to passive group. No differences were found in serum troponin I neither overtime nor between groups. In conclusion, an EAdi-based automated reverse triggering detection showed that this asynchrony is highly prevalent early after intubation under assist-control ventilation; the incidence depends on the magnitude of the activity detected and that reverse triggering seems to occur during the transition phase between deep sedation and the onset of patient triggering. In addition, the creation of a reverse triggering model revealed this phenomenon very complex, with high variability in terms of entrainment pattern and level of breathing effort. Finally, we have confirmed that RT dyssynchrony affects diaphragm function and this effect is modulated by the level of respiratory effort. Reverse triggering with low breathing effort seems to have a protective role on diaphragm function whereas reverse triggering with high breathing effort may favor eccentric myotrauma.Mechanical ventilation (MV) is used to sustain life in patients admitted to the intensive care unit for a wide spectrum of indications such as elective surgical procedures, septic shock, multiple organic failure and acute respiratory distress syndrome. Safe and effective ventilation depends on a smooth interaction between these two independent systems: the patient and the mechanical ventilator. Any mismatch between the patient and mechanical ventilator in terms of breath delivery timing, as well as the inability of the ventilator’s flow delivery to match the patient’s flow demand, is referred to as patient-ventilator dyssynchrony (PVD). Reverse Triggering (RT) is a type of PVD where muscle contractions are delayed, starting a certain amount of time after the machine triggered breath and occurring under different entrainment patterns. RT was originally described in 2013, in sedated patients admitted to the intensive care unit. Unfortunately, data about RT until now is scarce and its relevance remains totally uncertain. If any, the relevance of RT might be attributed to 2 main factors: the frequency of this PVD and its potential consequences in both lung and diaphragm injury. The group of different adverse patient–ventilator interactions leading to diaphragm atrophy and injury and resulting in a final common pathway of diaphragm weakness are denominated myotrauma. Particularly, RT is thought to cause eccentric myotrauma, which is a muscle contraction while muscle is lengthening during the ventilator’s expiratory phase while lung volume is decreasing. Based on animal and human studies, the impact of RT (if any) might be mediated by the level of breathing effort. In this thesis we aimed to describe the incidence of RT in patients early after intubation and admission to the intensive care unit and also to study the impact of RT with different levels of breathing effort on diaphragm injury (function and structure) in an animal model of RT with acute respiratory distress syndrome. To determine RT incidence, we conducted ancillary study in patients with continuous monitorization of the electrical activity of the diaphragm (EAdi). We developed a method for automatic detection of reverse triggering using EAdi and airway pressure curve. We additionally compared patients’ demographics, sedation depth and ventilation settings according to the median rate of reverse triggering, including time to transition to assisted ventilation or extubation. We found that our new automatic method presented a good diagnostic accuracy (98% total accuracy). Using a threshold of 1 µV for EAdi, median reverse triggering rate was 8% (range 0.1 to 75) with 44% (17 out of 39) of patients having ≥10% of breaths with reverse triggering. With 3 µV threshold, 26% (10 out of 39) of patients had ≥10% reverse triggered breaths. Importantly, patients who resented more reverse triggering were more likely to be on an assisted mode or extubated in the following 24 hours than patients who had low rate of RT (68% vs 35%; p=0.039). We also developed a 3 hours model of reverse triggering in pigs by modifying tidal volume, respiratory rate and level of sedation. Our approach to induce reverse triggering was not only feasible, but consistently reproducible in all animals, although with different presentations in terms of breathing effort and entrainment pattern. The most frequent entrainment pattern observed was 1:1, occurring in 83% of the total animals. Compared to passive ventilation (no breathing effort), RT group had significantly lower tidal volume (7 vs 10 ml/kg) and higher respiratory rate (45 vs 31 bpm) whereas no differences were found in other cardiorespiratory and sedation variables, nor in lung injury indicators after the study period. In order to study the impact of RT on diaphragm injury, we divided the RT group in 3 subgroups based on the level of breathing effort calculated by the pressure time product. Thus, 4 experimental groups were analyzed: Passive (no breathing effort), RT with low effort, RT with middle effort and RT with high effort. Function of the diaphragm was assessed by the ability to generate force, which correspond to the transdiaphragmatic pressure whilst diaphragm structure was evaluated using histological samples and serum troponin I as biomarker of muscle injury. We found that RT affects diaphragm function in two opposite directions. On one hand, animals with RT and low breathing effort showed a significant increase in force of 10% as compared to baseline. On the other hand, animals with RT and high breathing effort showed a larger decrease in force (34%) as compared to baseline. This difference was significantly different with the other experimental groups. Moreover, histologic analysis of diaphragm myofibers showed that RT with high breathing effort had significant lower myofiber cross-sectional area than passive group. Also, when comparing abnormal myofibers between groups, a significantly lower proportion of small fiber size were found in RT whit high breathing effort in comparison to passive group. No differences were found in serum troponin I neither overtime nor between groups. In conclusion, an EAdi-based automated reverse triggering detection showed that this asynchrony is highly prevalent early after intubation under assist-control ventilation; the incidence depends on the magnitude of the activity detected and that reverse triggering seems to occur during the transition phase between deep sedation and the onset of patient triggering. In addition, the creation of a reverse triggering model revealed this phenomenon very complex, with high variability in terms of entrainment pattern and level of breathing effort. Finally, we have confirmed that RT dyssynchrony affects diaphragm function and this effect is modulated by the level of respiratory effort. Reverse triggering with low breathing effort seems to have a protective role on diaphragm function whereas reverse triggering with high breathing effort may favor eccentric myotrauma.Mechanical ventilation (MV) is used to sustain life in patients admitted to the intensive care unit for a wide spectrum of indications such as elective surgical procedures, septic shock, multiple organic failure and acute respiratory distress syndrome. Safe and effective ventilation depends on a smooth interaction between these two independent systems: the patient and the mechanical ventilator. Any mismatch between the patient and mechanical ventilator in terms of breath delivery timing, as well as the inability of the ventilator’s flow delivery to match the patient’s flow demand, is referred to as patient-ventilator dyssynchrony (PVD). Reverse Triggering (RT) is a type of PVD where muscle contractions are delayed, starting a certain amount of time after the machine triggered breath and occurring under different entrainment patterns. RT was originally described in 2013, in sedated patients admitted to the intensive care unit. Unfortunately, data about RT until now is scarce and its relevance remains totally uncertain. If any, the relevance of RT might be attributed to 2 main factors: the frequency of this PVD and its potential consequences in both lung and diaphragm injury. The group of different adverse patient–ventilator interactions leading to diaphragm atrophy and injury and resulting in a final common pathway of diaphragm weakness are denominated myotrauma. Particularly, RT is thought to cause eccentric myotrauma, which is a muscle contraction while muscle is lengthening during the ventilator’s expiratory phase while lung volume is decreasing. Based on animal and human studies, the impact of RT (if any) might be mediated by the level of breathing effort. In this thesis we aimed to describe the incidence of RT in patients early after intubation and admission to the intensive care unit and also to study the impact of RT with different levels of breathing effort on diaphragm injury (function and structure) in an animal model of RT with acute respiratory distress syndrome. To determine RT incidence, we conducted ancillary study in patients with continuous monitorization of the electrical activity of the diaphragm (EAdi). We developed a method for automatic detection of reverse triggering using EAdi and airway pressure curve. We additionally compared patients’ demographics, sedation depth and ventilation settings according to the median rate of reverse triggering, including time to transition to assisted ventilation or extubation. We found that our new automatic method presented a good diagnostic accuracy (98% total accuracy). Using a threshold of 1 µV for EAdi, median reverse triggering rate was 8% (range 0.1 to 75) with 44% (17 out of 39) of patients having ≥10% of breaths with reverse triggering. With 3 µV threshold, 26% (10 out of 39) of patients had ≥10% reverse triggered breaths. Importantly, patients who resented more reverse triggering were more likely to be on an assisted mode or extubated in the following 24 hours than patients who had low rate of RT (68% vs 35%; p=0.039). We also developed a 3 hours model of reverse triggering in pigs by modifying tidal volume, respiratory rate and level of sedation. Our approach to induce reverse triggering was not only feasible, but consistently reproducible in all animals, although with different presentations in terms of breathing effort and entrainment pattern. The most frequent entrainment pattern observed was 1:1, occurring in 83% of the total animals. Compared to passive ventilation (no breathing effort), RT group had significantly lower tidal volume (7 vs 10 ml/kg) and higher respiratory rate (45 vs 31 bpm) whereas no differences were found in other cardiorespiratory and sedation variables, nor in lung injury indicators after the study period. In order to study the impact of RT on diaphragm injury, we divided the RT group in 3 subgroups based on the level of breathing effort calculated by the pressure time product. Thus, 4 experimental groups were analyzed: Passive (no breathing effort), RT with low effort, RT with middle effort and RT with high effort. Function of the diaphragm was assessed by the ability to generate force, which correspond to the transdiaphragmatic pressure whilst diaphragm structure was evaluated using histological samples and serum troponin I as biomarker of muscle injury. We found that RT affects diaphragm function in two opposite directions. On one hand, animals with RT and low breathing effort showed a significant increase in force of 10% as compared to baseline. On the other hand, animals with RT and high breathing effort showed a larger decrease in force (34%) as compared to baseline. This difference was significantly different with the other experimental groups. Moreover, histologic analysis of diaphragm myofibers showed that RT with high breathing effort had significant lower myofiber cross-sectional area than passive group. Also, when comparing abnormal myofibers between groups, a significantly lower proportion of small fiber size were found in RT whit high breathing effort in comparison to passive group. No differences were found in serum troponin I neither overtime nor between groups. In conclusion, an EAdi-based automated reverse triggering detection showed that this asynchrony is highly prevalent early after intubation under assist-control ventilation; the incidence depends on the magnitude of the activity detected and that reverse triggering seems to occur during the transition phase between deep sedation and the onset of patient triggering. In addition, the creation of a reverse triggering model revealed this phenomenon very complex, with high variability in terms of entrainment pattern and level of breathing effort. Finally, we have confirmed that RT dyssynchrony affects diaphragm function and this effect is modulated by the level of respiratory effort. Reverse triggering with low breathing effort seems to have a protective role on diaphragm function whereas reverse triggering with high breathing effort may favor eccentric myotrauma.Mechanical ventilation (MV) is used to sustain life in patients admitted to the intensive care unit for a wide spectrum of indications such as elective surgical procedures, septic shock, multiple organic failure and acute respiratory distress syndrome. Safe and effective ventilation depends on a smooth interaction between these two independent systems: the patient and the mechanical ventilator. Any mismatch between the patient and mechanical ventilator in terms of breath delivery timing, as well as the inability of the ventilator’s flow delivery to match the patient’s flow demand, is referred to as patient-ventilator dyssynchrony (PVD). Reverse Triggering (RT) is a type of PVD where muscle contractions are delayed, starting a certain amount of time after the machine triggered breath and occurring under different entrainment patterns. RT was originally described in 2013, in sedated patients admitted to the intensive care unit. Unfortunately, data about RT until now is scarce and its relevance remains totally uncertain. If any, the relevance of RT might be attributed to 2 main factors: the frequency of this PVD and its potential consequences in both lung and diaphragm injury. The group of different adverse patient–ventilator interactions leading to diaphragm atrophy and injury and resulting in a final common pathway of diaphragm weakness are denominated myotrauma. Particularly, RT is thought to cause eccentric myotrauma, which is a muscle contraction while muscle is lengthening during the ventilator’s expiratory phase while lung volume is decreasing. Based on animal and human studies, the impact of RT (if any) might be mediated by the level of breathing effort. In this thesis we aimed to describe the incidence of RT in patients early after intubation and admission to the intensive care unit and also to study the impact of RT with different levels of breathing effort on diaphragm injury (function and structure) in an animal model of RT with acute respiratory distress syndrome. To determine RT incidence, we conducted ancillary study in patients with continuous monitorization of the electrical activity of the diaphragm (EAdi). We developed a method for automatic detection of reverse triggering using EAdi and airway pressure curve. We additionally compared patients’ demographics, sedation depth and ventilation settings according to the median rate of reverse triggering, including time to transition to assisted ventilation or extubation. We found that our new automatic method presented a good diagnostic accuracy (98% total accuracy). Using a threshold of 1 µV for EAdi, median reverse triggering rate was 8% (range 0.1 to 75) with 44% (17 out of 39) of patients having ≥10% of breaths with reverse triggering. With 3 µV threshold, 26% (10 out of 39) of patients had ≥10% reverse triggered breaths. Importantly, patients who resented more reverse triggering were more likely to be on an assisted mode or extubated in the following 24 hours than patients who had low rate of RT (68% vs 35%; p=0.039). We also developed a 3 hours model of reverse triggering in pigs by modifying tidal volume, respiratory rate and level of sedation. Our approach to induce reverse triggering was not only feasible, but consistently reproducible in all animals, although with different presentations in terms of breathing effort and entrainment pattern. The most frequent entrainment pattern observed was 1:1, occurring in 83% of the total animals. Compared to passive ventilation (no breathing effort), RT group had significantly lower tidal volume (7 vs 10 ml/kg) and higher respiratory rate (45 vs 31 bpm) whereas no differences were found in other cardiorespiratory and sedation variables, nor in lung injury indicators after the study period. In order to study the impact of RT on diaphragm injury, we divided the RT group in 3 subgroups based on the level of breathing effort calculated by the pressure time product. Thus, 4 experimental groups were analyzed: Passive (no breathing effort), RT with low effort, RT with middle effort and RT with high effort. Function of the diaphragm was assessed by the ability to generate force, which correspond to the transdiaphragmatic pressure whilst diaphragm structure was evaluated using histological samples and serum troponin I as biomarker of muscle injury. We found that RT affects diaphragm function in two opposite directions. On one hand, animals with RT and low breathing effort showed a significant increase in force of 10% as compared to baseline. On the other hand, animals with RT and high breathing effort showed a larger decrease in force (34%) as compared to baseline. This difference was significantly different with the other experimental groups. Moreover, histologic analysis of diaphragm myofibers showed that RT with high breathing effort had significant lower myofiber cross-sectional area than passive group. Also, when comparing abnormal myofibers between groups, a significantly lower proportion of small fiber size were found in RT whit high breathing effort in comparison to passive group. No differences were found in serum troponin I neither overtime nor between groups. In conclusion, an EAdi-based automated reverse triggering detection showed that this asynchrony is highly prevalent early after intubation under assist-control ventilation; the incidence depends on the magnitude of the activity detected and that reverse triggering seems to occur during the transition phase between deep sedation and the onset of patient triggering. In addition, the creation of a reverse triggering model revealed this phenomenon very complex, with high variability in terms of entrainment pattern and level of breathing effort. Finally, we have confirmed that RT dyssynchrony affects diaphragm function and this effect is modulated by the level of respiratory effort. Reverse triggering with low breathing effort seems to have a protective role on diaphragm function whereas reverse triggering with high breathing effort may favor eccentric myotrauma.
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    Riesgo de Retención de Secreciones en Pacientes con Ventilación Mecánica Invasiva
    (2023) García Valdés, Patricio Hernán; Marambio Coloma, Consuelo Belén; Chamorro Gine, Magdalena; Basoalto Escobar, Roque Ignacio; Arellano, Daniel; Moya Gallardo, Eduardo Sebastián; Jalil Contreras, Yorschua Frederick; Damiani Rebolledo, L. Felipe
    Introducción. Los pacientes conectados a ventilación mecánica invasiva pueden presentar complicaciones respiratorias, donde la retención de secreciones es una de las más frecuentes. El drenaje y eliminación de las secreciones depende entre otras variables de los flujos respiratorios generados, donde una diferencia absoluta entre el flujo espiratorio máximo (FEM) y flujo inspiratorio máximo (FIM) menor a 17 L•min-1 o una relación FIM/FEM mayor a 0.9 favorecerían la retención de secreciones. Sin embargo, falta por determinar los flujos respiratorios resultantes y la proporción de pacientes con riesgo de retención de secreciones según estos parámetros. Objetivo. Determinar los flujos respiratorios durante la ventilación mecánica invasiva y la proporción de pacientes que se encuentra en riesgo de retención de secreciones. Métodos. Estudio descriptivo transversal desarrollado en la Unidad de Paciente Crítico Médico-Quirúrgico del “Hospital Clínico de la Red de Salud UC-CHRISTUS”. Se incluyeron pacientes adultos intubados y conectados a ventilación mecánica, en quienes se determinó los flujos respiratorios resultantes y se estimó la diferencia absoluta FEM-FIM, la relación FIM/FEM y la proporción de pacientes con riesgo de retención de secreciones. Resultados. Se incluyeron 100 pacientes, 45% presentaba entre sus diagnósticos patología respiratoria. La mediana de la diferencia absoluta entre FEM y FIM fue de 6 L•min-1 (-5 - 14.5) y la mediana de la tasa FIM/FEM de 0.87 (0.7 - 1.13). Un 84% presentó una diferencia absoluta entre FEM y FIM menor a 17 L•min-1, mientras que el 46% presentó una relación FIM/FEM mayor a 0.9. Conclusión. Una alta proporción de pacientes conectados a ventilación mecánica presenta riesgo de retención de secreciones independiente de la presencia o ausencia de patología respiratoria. Se requieren futuras investigaciones para evaluar el impacto de este criterio sobre complicaciones respiratorias.