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ABSTRACT Background: Driving pressure has been suggested to be the main driver of ventilator-induced lung injury and mortality in observational studies of acute respiratory distress syndrome. Whether a driving pressure-limiting strategy can improve clinical outcomes is unclear. Objective: To describe the protocol and statistical analysis plan that will be used to test whether a driving pressure-limiting strategy including positive end-expiratory pressure titration according to the best respiratory compliance and reduction in tidal volume is superior to a standard strategy involving the use of the ARDSNet low-positive end-expiratory pressure table in terms of increasing the number of ventilator-free days in patients with acute respiratory distress syndrome due to community-acquired pneumonia. Methods: The ventilator STrAtegy for coMmunIty acquired pNeumoniA (STAMINA) study is a randomized, multicenter, open-label trial that compares a driving pressure-limiting strategy to the ARDSnet low-positive end-expiratory pressure table in patients with moderate-to-severe acute respiratory distress syndrome due to community-acquired pneumonia admitted to intensive care units. We expect to recruit 500 patients from 20 Brazilian and 2 Colombian intensive care units. They will be randomized to a driving pressure-limiting strategy group or to a standard strategy using the ARDSNet low-positive end-expiratory pressure table. In the driving pressure-limiting strategy group, positive end-expiratory pressure will be titrated according to the best respiratory system compliance. Outcomes: The primary outcome is the number of ventilator-free days within 28 days. The secondary outcomes are in-hospital and intensive care unit mortality and the need for rescue therapies such as extracorporeal life support, recruitment maneuvers and inhaled nitric oxide. Conclusion: STAMINA is designed to provide evidence on whether a driving pressure-limiting strategy is superior to the ARDSNet low-positive end-expiratory pressure table strategy for increasing the number of ventilator-free days within 28 days in patients with moderate-to-severe acute respiratory distress syndrome. Here, we describe the rationale, design and status of the trial.

RESUMO Contexto: Em estudos observacionais sobre a síndrome do desconforto respiratório agudo, sugeriu-se que a driving pressure é o principal fator de lesão pulmonar induzida por ventilador e de mortalidade. Não está claro se uma estratégia de limitação da driving pressure pode melhorar os desfechos clínicos. Objetivo: Descrever o protocolo e o plano de análise estatística que serão usados para testar se uma estratégia de limitação da driving pressure envolvendo a titulação da pressão positiva expiratória final de acordo com a melhor complacência respiratória e a redução do volume corrente é superior a uma estratégia padrão envolvendo o uso da tabela de pressão positiva expiratória final baixa do protocolo ARDSNet, em termos de aumento do número de dias sem ventilador em pacientes com síndrome do desconforto respiratório agudo devido à pneumonia adquirida na comunidade. Métodos: O estudo STAMINA (ventilator STrAtegy for coMmunIty acquired pNeumoniA) é randomizado, multicêntrico e aberto e compara uma estratégia de limitação da driving pressure com a tabela de pressão positiva expiratória final baixa do protocolo ARDSnet em pacientes com síndrome do desconforto respiratório agudo moderada a grave devido à pneumonia adquirida na comunidade internados em unidades de terapia intensiva. Esperamos recrutar 500 pacientes de 20 unidades de terapia intensiva brasileiras e duas colombianas. Eles serão randomizados para um grupo da estratégia de limitação da driving pressure ou para um grupo de estratégia padrão usando a tabela de pressão positiva expiratória final baixa do protocolo ARDSnet. No grupo da estratégia de limitação da driving pressure, a pressão positiva expiratória final será titulada de acordo com a melhor complacência do sistema respiratório. Desfechos: O desfecho primário é o número de dias sem ventilador em 28 dias. Os desfechos secundários são a mortalidade hospitalar e na unidade de terapia intensiva e a necessidade de terapias de resgate, como suporte de vida extracorpóreo, manobras de recrutamento e óxido nítrico inalado. Conclusão: O STAMINA foi projetado para fornecer evidências sobre se uma estratégia de limitação da driving pressure é superior à estratégia da tabela de pressão positiva expiratória final baixa do protocolo ARDSnet para aumentar o número de dias sem ventilador em 28 dias em pacientes com síndrome do desconforto respiratório agudo moderada a grave. Aqui, descrevemos a justificativa, o desenho e o status do estudo.

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OBJECTIVE: To evaluate the acute effects of expiratory positive airway pressure (EPAP) on exercise tolerance, dyspnea, leg discomfort, and breathing pattern in patients with COPD. METHODS: Fifteen patients with COPD were assessed with the following three different protocols: EPAP of 7.5 cmH2O used during a constant cycle ergometer exercise test (Protocol-1); EPAP of 7.5 cmH2O used for 15 minutes before the test (Protocol-2); and a sham system without pressure used for 15 minutes before the test (Protocol-3). Dyspnea and leg discomfort were assessed using Borg scale, whereas breathing pattern by optoelectronic plethysmography. Statistical analyses were performed using generalized estimating equations and Bonferroni tests (α = 5%), considering the protocols (1, 2, and 3) and moment (resting and the end of exercise). RESULTS: Exercise tolerance was lower in protocol 1: 108 ± 45 seconds compared to protocols 2: 187 ± 99 seconds (p= .011) and 3: 183 ± 101 seconds (p= .021). No difference was observed between protocols 2 and 3 (p> .999). Dyspnea in protocol 1: 7.0 ± 2.08 was higher than protocols 2: 4.10 ± 2.45 (p= .001) and 3: 3.90 ± 2.21 (p< .001), but no differences were observed between protocols 2 and 3 (p> .999). No significant difference was observed for leg discomfort among the protocols (p= .137). There were no statistically significant differences for most variables of breathing pattern among the protocols. CONCLUSION: A reduction on exercise tolerance and an increase in dyspnea were found with EPAP of 7.5 cm H2O during a constant cycle ergometer exercise test in patients with COPD.

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Resumo Objetivo Avaliar o efeito do uso de ventilação mecânica com pressão positiva expiratória final (PEEP) na função renal dos pacientes internados em Unidade de Terapia Intensiva (UTI). Métodos Estudo de coorte retrospectivo, quantitativo, desenvolvido na UTI de um hospital público de Brasília, Distrito Federal. A amostra foi constituída de 52 prontuários de pacientes internados na UTI de novembro de 2016 a dezembro de 2018. A coleta dos dados foi realizada por meio de um questionário com dados demográficos, clínicos e laboratoriais. Os pacientes foram alocados em grupos: (1) PEEP ≤ 5 cmH2O, (2) PEEP > 5 cmH2O e < 10 cmH2O e (3) PEEP ≥ 10 cmH2O. Resultados A média de idade dos pacientes foi de 59 anos e 50% deles tinha mais de 63 anos. Constatou-se que 63,16% dos pacientes que estavam em ventilação mecânica com pressão positiva ao final da expiração ≥ 10 cmH2O evoluíram no estágio 1 (menor gravidade de lesão renal aguda (LRA)) e 21,5% no estágio 2 (moderada gravidade). Ainda assim, um pequeno percentual (5,8%) de pacientes evoluiu a óbito. Pacientes sem sucesso no desmame da ventilação mecânica apresentaram 10,24 vezes a chance de evoluir com LRA. Conclusão o emprego da ventilação mecânica pode determinar danos à função renal dos pacientes internados em unidade de terapia intensiva e que aqueles com maior necessidade de oferta de PEEP evoluíram com diferentes gravidades e persistência da LRA.

Resumen Objetivo Evaluar el efecto del uso de la ventilación mecánica con presión positiva espiratoria final (PEEP) en la función renal de los pacientes internados en Unidad de Cuidados Intensivos (UTI). Métodos Estudio de corte retrospectivo, cuantitativo, desarrollado en la UCI de un hospital público de Brasília, Distrito Federal. La amuestra estuvo constituida por 52 prontuarios de pacientes internados en la UCI de noviembre de 2016 a diciembre de 2018. La recolección de los datos se realizó por medio de un cuestionario con datos demográficos, clínicos y laboratoriales. Los pacientes fueron distribuidos en grupos: (1) PEEP ≤ 5 cmH2O, (2) PEEP > 5 cmH2O y < 10 cmH2O y (3) PEEP ≥ 10 cmH2O. Resultados El promedio de edad de los pacientes era de 59 años y el 50 % de ellos tenía más de 63 años. Se constató que el 63,16 % de los pacientes que estaban en ventilación mecánica con presión positiva al final de la expiración ≥ 10 cmH2O evolucionaron en la etapa 1 (menor gravedad de lesión renal aguda (LRA)) y 21,5 % en la etapa 2 (moderada gravedad). Aun así, un pequeño porcentaje (5,8 %) de pacientes falleció. Pacientes sin éxito en la descontinuación de la ventilación mecánica presentaron 10,24 veces la posibilidad de evolucionar con LRA. Conclusión el uso de la ventilación mecánica puede determinar daños a la función renal de los pacientes internados en una unidad de cuidados intensivos y que los que tengan una mayor necesidad de oferta de PEEP evolucionaron con distintas gravedades y persistencia de la LRA.

Abstract Objective To assess the effect of using mechanical ventilation with positive end-expiratory pressure (PEEP) on the renal function of patients admitted to the Intensive Care Unit (ICU). Methods This is a quantitative retrospective cohort study developed in the ICU of a public hospital in Brasília, Distrito Federal. The sample consisted of 52 medical records of patients admitted to the ICU from November 2016 to December 2018. Data collection was performed through a questionnaire with demographic, clinical and laboratory data. Patients were allocated in two groups: (1) PEEP ≤ 5 cmH2O, (2) PEEP > 5 cmH2O and < 10 cmH2O, and (3) PEEP ≥ 10 cmH2O. Results The mean age of patients was 59 years and 50% of them were over 63 years. It was found that 63.16% of patients who were on mechanical ventilation with positive end-expiratory pressure ≥ 10 cmH2O evolved in stage 1 (less severe acute kidney injury (AKI)) and 21.5% in stage 2 (moderate gravity). Even so, a small percentage (5.8%) of patients died. Patients who were unsuccessful in weaning from mechanical ventilation had a 10.24-fold chance of developing AKI. Conclusion mechanical ventilation use can cause damage to the renal function of patients hospitalized in the intensive care unit and that those with greater need to offer PEEP evolved with different severities and persistence of AKI.

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Patients with hemodynamic instability have a sustained systolic blood pressure less or equal to 90 mmHg, a heart rate greater or equal to 120 beats per minute and an acute compromise of the ventilation/oxygenation ratio and/or an altered state of consciousness upon admission. These patients have higher mortality rates due to massive hemorrhage, airway injury and/or impaired ventilation. Damage control resuscitation is a systematic approach that aims to limit physiologic deterioration through strategies that address the physiologic debt of trauma. This article aims to describe the experience earned by the Trauma and Emergency Surgery Group (CTE) of Cali, Colombia in the management of the severely injured trauma patient in the emergency department following the basic principles of damage control surgery. Since bleeding is the main cause of death, the management of the severely injured trauma patient in the emergency department requires a multidisciplinary team that performs damage control maneuvers aimed at rapidly controlling bleeding, hemostatic resuscitation, and/or prompt transfer to the operating room, if required.

Un paciente politraumatizado hemodinámicamente inestable es aquel que ingresa al servicio de urgencias con una presión arterial sistólica menor o igual de 90 mmHg, una frecuencia cardiaca mayor o igual a 120 latidos por minuto y un compromiso agudo de la relación ventilación/oxigenación y/o del estado de conciencia. Por esta razón, existe una alta mortalidad dentro de las primeras horas de un trauma severo ya sea por una hemorragia masiva, una lesión de la vía aérea y/o una alteración de la ventilación. Siendo el objetivo de este artículo describir el manejo en urgencias del paciente politraumatizado hemodinámicamente inestable de acuerdo con los principios de control de daños. El manejo del paciente politraumatizado es una estrategia dinámica de alto impacto que requiere de un equipo multidisciplinario de experiencia. El cual debe de evolucionar conjunto a las nuevas herramientas de diagnóstico y tratamiento endovascular que buscan ser un puente para lograr una menor repercusión hemodinámica en el paciente y una más rápida y efectiva estabilización con mayores tasas de sobrevida.

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Abstract Patients with hemodynamic instability have a sustained systolic blood pressure less or equal to 90 mmHg, a heart rate greater or equal to 120 beats per minute and an acute compromise of the ventilation/oxygenation ratio and/or an altered state of consciousness upon admission. These patients have higher mortality rates due to massive hemorrhage, airway injury and/or impaired ventilation. Damage control resuscitation is a systematic approach that aims to limit physiologic deterioration through strategies that address the physiologic debt of trauma. This article aims to describe the experience earned by the Trauma and Emergency Surgery Group (CTE) of Cali, Colombia in the management of the severely injured trauma patient in the emergency department following the basic principles of damage control surgery. Since bleeding is the main cause of death, the management of the severely injured trauma patient in the emergency department requires a multidisciplinary team that performs damage control maneuvers aimed at rapidly controlling bleeding, hemostatic resuscitation, and/or prompt transfer to the operating room, if required.

Resumen Un paciente politraumatizado hemodinámicamente inestable es aquel que ingresa al servicio de urgencias con una presión arterial sistólica menor o igual de 90 mmHg, una frecuencia cardiaca mayor o igual a 120 latidos por minuto y un compromiso agudo de la relación ventilación/oxigenación y/o del estado de conciencia. Por esta razón, existe una alta mortalidad dentro de las primeras horas de un trauma severo ya sea por una hemorragia masiva, una lesión de la vía aérea y/o una alteración de la ventilación. Siendo el objetivo de este artículo describir el manejo en urgencias del paciente politraumatizado hemodinámicamente inestable de acuerdo con los principios de control de daños. El manejo del paciente politraumatizado es una estrategia dinámica de alto impacto que requiere de un equipo multidisciplinario de experiencia. El cual debe de evolucionar conjunto a las nuevas herramientas de diagnóstico y tratamiento endovascular que buscan ser un puente para lograr una menor repercusión hemodinámica en el paciente y una más rápida y efectiva estabilización con mayores tasas de sobrevida.

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The CLIC system in the Dräger Apollo anesthesia workstation allows a successful pre-use machine checkout without the presence of a carbon dioxide absorbent canister. It also allows the canister to be changed without interrupting controlled ventilation. However, this canister can be easily installed improperly with the CLIC adapter. We report a case in which a patient could not be ventilated by mask after the induction of general anesthesia, resulting in oxygen desaturation before successful ventilation was achieved with a bag valve mask. This case illustrates the importance of a leak test after components of the breathing circuit are changed.

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BACKGROUND: Patients with decreased consciousness are prone to prolonged bed rest and respiratory complications. If effective in reducing atelectasis, lung expansion maneuvers could be used to prevent these complications. In comatose, bedridden subjects, we aimed to assess the acute effect on regional lung aeration of 2 lung expansion techniques: expiratory positive airway pressure and the breath-stacking maneuver. Our secondary aim was to evaluate the influence of these lung expansion techniques on regional ventilation distribution, regional ventilation kinetics, respiratory pattern, and cardiovascular system. METHODS: We enrolled 10 subjects status post neurosurgery, unable to follow commands, and with prolonged bed rest. All subjects were submitted to both expansion techniques in a randomized order. Regional lung aeration, ventilation distribution, and regional ventilation kinetics were measured with electrical impedance tomography. RESULTS: Lung aeration increased significantly during the application of both expiratory positive airway pressure and breath-stacking (P < .001) but returned to baseline values seconds afterwards. The posterior lung regions had the largest volume increase (P < .001 for groups). Both maneuvers induced asynchronous inflation and deflation between anterior and posterior lung regions. There were no significant differences in cardiovascular variables. CONCLUSIONS: In comatose subjects with prolonged bed rest, expiratory positive airway pressure and breath-stacking promoted brief increases in lung aeration. (ClinicalTrials.gov registration NCT02613832.).

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RESUMO A pandemia por COVID-19 tem deixado os gestores, os profissionais de saúde e a população preocupados com a potencial escassez de ventiladores pulmonares para suporte de pacientes graves. No Brasil, há diversas iniciativas com o intuito de produzir ventiladores alternativos para ajudar a suprir essa demanda. Para auxiliar as equipes que atuam nessas iniciativas, são expostos alguns conceitos básicos sobre fisiologia e mecânica respiratória, os termos comumente utilizados no contexto da ventilação mecânica, as fases do ciclo ventilatório, as diferenças entre disparo e ciclagem, os modos ventilatórios básicos e outros aspectos relevantes, como mecanismos de lesão pulmonar induzida pela ventilação mecânica, pacientes com drive respiratório, necessidade de umidificação de vias aéreas, risco de contaminação cruzada e disseminação de aerossóis. Após a fase de desenvolvimento de protótipo, são necessários testes pré-clínicos de bancada e em modelos animais, a fim de determinar a segurança e o desempenho dos equipamentos, seguindo requisitos técnicos mínimos exigidos. Então, é imprescindível passar pelo processo regulatório exigido pela Agência Nacional de Vigilância Sanitária (ANVISA). A empresa responsável pela fabricação do equipamento deve estar regularizada junto à ANVISA, que também deve ser notificada da condução dos testes clínicos em humanos, seguindo protocolo de pesquisa aprovado pelo Comitê de Ética em Pesquisa. O registro do ventilador junto à ANVISA deve ser acompanhado de um dossiê, composto por documentos e informações detalhadas neste artigo, que não tem o propósito de esgotar o assunto, mas de nortear os procedimentos necessários.

ABSTRACT The COVID-19 pandemic has brought concerns to managers, healthcare professionals, and the general population related to the potential mechanical ventilators' shortage for severely ill patients. In Brazil, there are several initiatives aimed at producing alternative ventilators to cover this gap. To assist the teams that work in these initiatives, we provide a discussion of some basic concepts on physiology and respiratory mechanics, commonly used mechanical ventilation terms, the differences between triggering and cycling, the basic ventilation modes and other relevant aspects, such as mechanisms of ventilator-induced lung injury, respiratory drive, airway heating and humidification, cross-contamination risks, and aerosol dissemination. After the prototype development phase, preclinical bench-tests and animal model trials are needed to determine the safety and performance of the ventilator, following the minimum technical requirements. Next, it is mandatory going through the regulatory procedures as required by the Brazilian Health Regulatory Agency (Agência Nacional de Vigilância Sanitária - ANVISA). The manufacturing company should be appropriately registered by ANVISA, which also must be notified about the conduction of clinical trials, following the research protocol approval by the Research Ethics Committee. The registration requisition of the ventilator with ANVISA should include a dossier containing the information described in this paper, which is not intended to cover all related matters but to provide guidance on the required procedures.

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BACKGROUND: Protective mechanical ventilation is recommended for patients with acute respiratory distress syndrome (ARDS), but it usually requires controlled ventilation and sedation. Using neurally adjusted ventilatory assist (NAVA) or pressure support ventilation (PSV) could have additional benefits, including the use of lower sedative doses, improved patient-ventilator interaction and shortened duration of mechanical ventilation. We designed a pilot study to assess the feasibility of keeping tidal volume (VT) at protective levels with NAVA and PSV in patients with ARDS. METHODS: We conducted a prospective randomized crossover trial in five ICUs from a university hospital in Brazil and included patients with ARDS transitioning from controlled ventilation to partial ventilatory support. NAVA and PSV were applied in random order, for 15 min each, followed by 3 h in NAVA. Flow, peak airway pressure (Paw) and electrical activity of the diaphragm (EAdi) were captured from the ventilator, and a software (Matlab, Mathworks, USA), automatically detected inspiratory efforts and calculated respiratory rate (RR) and VT. Asynchrony events detection was based on waveform analysis. RESULTS: We randomized 20 patients, but the protocol was interrupted for five (25%) patients for whom we were unable to maintain VT below 6.5 mL/kg in PSV due to strong inspiratory efforts and for one patient for whom we could not detect EAdi signal. For the 14 patients who completed the protocol, VT was 5.8 ± 1.1 mL/kg for NAVA and 5.6 ± 1.0 mL/kg for PSV (p = 0.455) and there were no differences in RR (24 ± 7 for NAVA and 23 ± 7 for PSV, p = 0.661). Paw was greater in NAVA (21 ± 3 cmH2O) than in PSV (19 ± 3 cmH2O, p = 0.001). Most patients were under continuous sedation during the study. NAVA reduced triggering delay compared to PSV (p = 0.020) and the median asynchrony Index was 0.7% (0-2.7) in PSV and 0% (0-2.2) in NAVA (p = 0.6835). CONCLUSIONS: It was feasible to keep VT in protective levels with NAVA and PSV for 75% of the patients. NAVA resulted in similar VT, RR and Paw compared to PSV. Our findings suggest that partial ventilatory assistance with NAVA and PSV is feasible as a protective ventilation strategy in selected ARDS patients under continuous sedation. Trial registration ClinicalTrials.gov (NCT01519258). Registered 26 January 2012, https://clinicaltrials.gov/ct2/show/NCT01519258.

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La enfermedad por coronavirus 2019 o COVID-19 se transmite principalmente a través de gotas respiratorias, contacto cercano no protegido y procedimientos generadores de aerosoles (1). Las pruebas realizadas en un laboratorio de sueño y la terapia con presión positiva, como la CPAP o la BPAP, pueden aumentar el riesgo de exposición de transmisión de COVID-19 al personal médico y a los pacientes. Las decisiones basadas en la evidencia son el estándar ideal; sin embargo, esta evidencia va apareciendo poco a poco, a un ritmo más lento que la emergencia de salud pública que estamos viviendo; por tanto, por el momento debemos basar nuestras decisiones en la experiencia, en documentos de consenso, cuando estén disponibles, y en el juicio clínico, cuando no exista evidencia. Nuestro objetivo es proporcionar unas recomendaciones, teniendo como marco de referencia las dictadas por organismos nacionales e internacionales, como la Asociación Colombiana de Medicina del Sueño, la Academia Americana de Medicina del Sueño, la Academia Mexicana de Medicina del Dormir y otras publicaciones en revistas indexadas (2,3).

The coronavirus disease 2019 or COVID-19 is transmitted primarily through respiratory drops, unprotected close contact, and aerosol-generating procedures (1). Tests performed in a sleep laboratory and positive pressure therapy such as CPAP or BPAP, may increase the risk of exposure of transmission of COVID-19 to clinicians and patients. Evidence-based making decisions are the ideal standard, however, this evidence appears little by little, at a slower rate than the public health emergency that we are experiencing; therefore, for the moment, our decisions must be based on our experience, on consensus documents, when they are available, and clinical judgment when there is no evidence. Our objective is to give recommendations, taking as a reference framework those issued by national and international organizations, such as Colombian Asociation of Sleep Medicine, the American Academy of Sleep Medicine, the Mexican Academy of Sleep Medicine, and other publications in indexed journals.

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Abstract Objective: To evaluate the impact of different levels of positive end-expiratory pressure (PEEP) on gas exchange in patients undergoing coronary artery bypass grafting (CABG). Methods: A randomized clinical trial was conducted with patients undergoing CABG surgery. Patients were randomized into three groups: Group 10, PEEP of 10 cmH2O; Group 12, PEEP of 12 cmH2O; and Group 15, PEEP of 15 cmH2O. After the randomization, all patients underwent gas analysis at three moments: (1) before lung expansion therapy (LET); (2) 30 minutes after LET; and (3) one hour after extubation. Results: Sixty-six patients were studied, of which 61.7% were men, with mean age of 64 ± 8.9 years. Patients allocated to Group 15 showed a significant improvement in gas exchange comparing pre- and post-expansion values (239±21 vs. 301±19, P<0,001) and the increase was maintained after extubation (278±26). Despite the use of high levels of PEEP, no significant hemodynamic change was evidenced. Conclusion: It is concluded that high levels of PEEP (15 cmH2O) are beneficial for the improvement of gas exchange in patients undergoing CABG.

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OBJECTIVE: To evaluate the impact of different levels of positive end-expiratory pressure (PEEP) on gas exchange in patients undergoing coronary artery bypass grafting (CABG). METHODS: A randomized clinical trial was conducted with patients undergoing CABG surgery. Patients were randomized into three groups: Group 10, PEEP of 10 cmH2O; Group 12, PEEP of 12 cmH2O; and Group 15, PEEP of 15 cmH2O. After the randomization, all patients underwent gas analysis at three moments: (1) before lung expansion therapy (LET); (2) 30 minutes after LET; and (3) one hour after extubation. RESULTS: Sixty-six patients were studied, of which 61.7% were men, with mean age of 64 ± 8.9 years. Patients allocated to Group 15 showed a significant improvement in gas exchange comparing pre- and post-expansion values (239±21 vs. 301±19, P<0,001) and the increase was maintained after extubation (278±26). Despite the use of high levels of PEEP, no significant hemodynamic change was evidenced. CONCLUSION: It is concluded that high levels of PEEP (15 cmH2O) are beneficial for the improvement of gas exchange in patients undergoing CABG.

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RESUMO Objetivo: Avaliar os efeitos da hiperinsuflação com o ventilador sobre a mecânica respiratória. Métodos: Foi realizado ensaio clínico cruzado randomizado com 38 pacientes ventilados mecanicamente com infecção pulmonar. A ordem da hiperinsuflação ou controle (sem alterações nos parâmetros) foi randomizada. A hiperinsuflação foi realizada por 5 minutos no modo ventilação com pressão controlada, com aumentos progressivos de 5cmH2O até atingir pressão máxima de 35cmH2O, mantendo-se a pressão positiva expiratória final. Após atingir 35cmH2O, o tempo inspiratório e a frequência respiratória foram ajustados para que os fluxos inspiratório e expiratório atingissem a linha de base, respectivamente. As medidas de complacência estática, resistências total e de vias aéreas e pico de fluxo expiratório foram avaliadas antes, imediatamente após a manobra e após aspiração. Foi utilizada a análise de variância two-way para medidas repetidas com pós-teste de Tukey, considerando significativo p < 0,05. Resultados: A hiperinsuflação com o ventilador aumentou a complacência estática, mantendo-se após aspiração (46,2 ± 14,8 versus 52,0 ± 14,9 versus 52,3 ± 16,0mL/cmH2O; p < 0,001). Houve aumento transitório da resistência de vias aéreas (6,6 ± 3,6 versus 8,0 ± 5,5 versus 6,6 ± 3,5cmH2O/L.s-1; p < 0,001) e redução transitória do pico de fluxo expiratório (32,0 ± 16,0 versus 29,8 ± 14,8 versus 32,1 ± 15,3Lpm; p < 0,05) imediatamente após a manobra, com redução após aspiração traqueal. Não foram observadas modificações no controle e nem alterações hemodinâmicas. Conclusão: A hiperinsuflação com o ventilador promoveu aumento da complacência associado ao aumento transitório da resistência de vias aéreas e do pico de fluxo expiratório, com redução após aspiração.

ABSTRACT Objective: To evaluate the effects of ventilator hyperinflation on respiratory mechanics. Methods: A randomized crossover clinical trial was conducted with 38 mechanically ventilated patients with pulmonary infection. The order of the hyperinflation and control (without changes in the parameters) conditions was randomized. Hyperinflation was performed for 5 minutes in pressure-controlled ventilation mode, with progressive increases of 5cmH2O until a maximum pressure of 35cmH2O was reached, maintaining positive end expiratory pressure. After 35cmH2O was reached, the inspiratory time and respiratory rate were adjusted so that the inspiratory and expiratory flows reached baseline levels. Measurements of static compliance, total resistance and airway resistance, and peak expiratory flow were evaluated before the technique, immediately after the technique and after aspiration. Two-way analysis of variance for repeated measures was used with Tukey's post hoc test, and p < 0.05 was considered significant. Results: Ventilator hyperinflation increased static compliance, which remained at the same level after aspiration (46.2 ± 14.8 versus 52.0 ± 14.9 versus 52.3 ± 16.0mL/cmH2O; p < 0.001). There was a transient increase in airway resistance (6.6 ± 3.6 versus 8.0 ± 5.5 versus 6.6 ± 3.5cmH2O/Ls-1; p < 0.001) and a transient reduction in peak expiratory flow (32.0 ± 16.0 versus 29.8 ± 14.8 versus 32.1 ± 15.3Lpm; p <0.05) immediately after the technique; these values returned to pretechnique levels after tracheal aspiration. There were no changes in the control condition, nor were hemodynamic alterations observed. Conclusion: Ventilator hyperinflation promoted increased compliance associated with a transient increase in airway resistance and peak expiratory flow, with reduction after aspiration.

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SUMMARY OBJECTIVE: To verify the association between prone position, increased diuresis, and decreased cumulative fluid balance in critically ill pediatric patients who underwent mechanical ventilation (MV) for pulmonary causes and describe adverse events related to the use of the position. METHODS: This is a retrospective observational study. Patients aged between 1 month and 12 years who underwent MV for pulmonary causes, between January 2013 and December 2015, were selected and divided between those who were put on prone position (PG) and those who were not (CG) during the hospitalization at the Pediatric Intensive Care Unit (PICU). Data were analyzed longitudinally from D1 to D4. RESULTS: A total of 77 patients (PG = 37 and CG = 40) were analyzed. The general characteristics of both groups were similar. In the comparison between the groups, there was no increase in diuresis or decrease in cumulative fluid balance in the prone group. In the longitudinal analysis of D1 to D4, we saw that the PG presented higher diuresis (p = 0.034) and a lower cumulative fluid balance (p = 0.001) in D2. Regarding the use of diuretics, there was greater use of furosemide (P <0.001) and spironolactone (P = 0.04) in the PG. There was no increase in adverse events during the use of the prone position. CONCLUSION: The prone position was not associated with increased diuresis or decreased cumulative fluid balance in critically ill pediatric patients who underwent to MV for pulmonary causes.

RESUMO OBJETIVO: Verificar a associação entre posição prona, aumento da diurese e diminuição do balanço hídrico em pacientes pediátricos criticamente enfermos e submetidos à ventilação mecânica (VM) por causa pulmonar, além de descrever eventuais intercorrências relacionadas à aplicação dessa posição. MÉTODOS: Estudo observacional retrospectivo. Pacientes submetidos à VM por causa pulmonar, com idade entre 1 mês e 12 anos no período entre janeiro de 2013 e dezembro de 2015, foram selecionados e divididos entre os que receberam posição prona (GP) e os que não receberam (GC) durante a internação na Unidade de Terapia Intensiva Pediátrica (Utip). Os dados foram analisados longitudinalmente de D1 a D4. RESULTADOS: Foram analisados77 pacientes (GP=37 e GC=40). Em termos de características gerais, os grupos foram semelhantes entre si. Na comparação entre os grupos, não houve aumento da diurese ou diminuição do balanço hídrico cumulativo no grupo prona. Na análise longitudinal de D1 a D4, evidenciou-se que o GP apresentou maior diurese (p=0,034) e menor balanço hídrico cumulativo (p = 0,001) no D2. Com relação ao uso de diuréticos, houve maior uso de furosemida (P<0,001) e de espironolactona (P=0,04) no GP. Não houve aumento de eventos adversos durante a utilização da posição prona. CONCLUSÃO: A posição prona não demonstrou associação com aumento da diurese ou diminuição de balanço hídrico cumulativo em pacientes críticos pediátricos submetidos à VM por causa pulmonar.

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Abstract Objective: To compare the effects of extended- versus short-time noninvasive positive pressure ventilation on pulmonary function, tissue perfusion, and clinical outcomes in the early postoperative period following coronary artery bypass surgery in patients with preserved left ventricular function. Methods: Patients were randomized into two groups according to noninvasive positive pressure ventilation intensity: short-time noninvasive positive pressure ventilation n=20 (S-NPPV) and extended-time noninvasive positive pressure ventilation n=21 (E-NPPV). S-NPPV was applied for 60 minutes during immediate postoperative period and 10 minutes, twice daily, from postoperative days 1-5. E-NPPV was performed for at least six hours during immediate postoperative period and 60 minutes, twice daily, from postoperative days 1-5. As a primary outcome, tissue perfusion was determined by central venous oxygen saturation and blood lactate level measured after anesthetic induction, immediately after extubation and following noninvasive positive pressure ventilation protocols. As a secondary outcome, pulmonary function tests were performed preoperatively and in the postoperative days 1, 3, and 5; clinical outcomes were recorded. Results: Significant drop in blood lactate levels and an improvement in central venous oxygen saturation values in the E-NPPV group were observed when compared with S-NPPV group after study protocol (P<0.01). The E-NPPV group presented higher preservation of postoperative pulmonary function as well as lower incidence of respiratory events and shorter postoperative hospital stay (P<0.05). Conclusion: Prophylactic E-NPPV administered in the early postoperative period of coronary artery bypass surgery resulted in greater improvements in tissue perfusion, pulmonary function and clinical outcomes than S-NPPV, in patients with preserved left ventricular function. Trial Registration: Brazilian Registry of Clinical trial - RBR7sqj78 - http://www.ensaiosclinicos.gov.br

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ABSTRACT CONTEXT: Mounier-Kuhn syndrome is a rare congenital condition with distinct dilatation and diverticulation of the tracheal wall. The symptoms may vary and the treatment usually consists of support. CASE REPORT: The patient was a 60-year-old male with recurrent hospital admission. He was admitted in this case due to dyspnea, cough and sputum production. An arterial blood sample revealed decompensated respiratory acidosis with moderate hypoxemia. A chest computed tomography (CT) scan showed dilatation of the trachea and bronchi, tracheal diverticula and bronchiectasis. Flexible bronchoscopy was performed, which revealed enlarged airways with expiratory collapse. Furthermore, orifices of tracheal diverticulosis were also detected. Non-invasive positive pressure ventilation (NPPV) was added, along with long-term oxygen therapy. At control visits, the patient's clinical and laboratory findings were found to have improved. CONCLUSION: Flexible bronchoscopy can be advocated for establishing the diagnosis and non-invasive mechanical ventilation can be used with a high success rate, for clinical wellbeing in Mounier-Kuhn syndrome.

RESUMO CONTEXTO: A síndrome de Mounier-Kuhn é uma condição congênita rara com dilatação e diverticulação distintas da parede traqueal. Os sintomas podem ser variáveis ​e o tratamento geralmente é de suporte. RELATO DE CASO: Paciente do sexo masculino, de 60 anos, com internação hospitalar recorrente, foi internado neste caso devido a dispneia, tosse e produção de expectoração. A amostra de sangue arterial revelou acidose respiratória descompensada, com hipoxemia moderada. A tomografia computadorizada de tórax mostrou dilatação da traqueia e brônquios, divertículos traqueais e bronquiectasias. Realizou-se broncoscopia flexível, que revelou aumento das vias aéreas com colapso expiratório. Além disso, também foram detectados orifícios de diverticulose traqueal. Foi adicionada ventilação com pressão positiva não invasiva (NPPV) juntamente com a oxigenoterapia a longo prazo. Foram verificadas melhoras dos resultados clínicos e laboratoriais do doente nas visitas de controle. CONCLUSÃO: A broncoscopia flexível pode ser defendida para estabelecer o diagnóstico, e a ventilação mecânica não invasiva pode ser utilizada com alta taxa de sucesso, para bem-estar clínico, na síndrome de Mounier-Kuhn.

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The aim of this study was to evaluate the effect of expiratory positive airway pressure (EPAP) on heart rate variability (HRV) indices at rest and during 6-min walk test (6MWT) in chronic obstructive pulmonary disease (COPD) patients. Fifteen moderate to severe COPD patients were randomized and evaluated with and without (Non-EPAP) a 5 cmH2O EPAP device. Respiratory rate (RR) was collected at rest (5 min), during the 6MWT (5 min), and at recovery (5 min). Indices of HRV were computed in the time domain, in the frequency domain, and nonlinear analysis. For EPAP and Non-EPAP during the 6MWT, we found an increased mean heart rate (HR) (P=0.001; P=0.001) while mean RR (P=0.001; P=0.015) and RR tri index decreased (P=0.006; P=0.028). Peripheral oxygen saturation (P=0.019) increased at rest only in the EPAP group. In EPAP, correlations were found between forced expiratory volume in 1 s (FEV1) and low frequency (LF) sympathetic tonus (P=0.05; r=-0.49), FEV1 and high frequency (HF) parasympathetic tonus at rest (P=0.05; r=0.49), lactate at rest and LF during the 6MWT (P=0.02; r=-0.57), and lactate at rest and HF during 6MWT (P=0.02; r=0.56). Through a linear regression model, we found that lactate at rest explained 27% of the alterations of LF during 6MWT. The use of 5 cmH2O EPAP improved autonomic cardiac modulation and its complexity at rest in COPD patients. Although it did not influence the performance of the 6MWT, the EPAP device caused alterations in resting lactate concentration with an effect on sympatho-vagal control during the test.

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RESUMO O objetivo deste trabalho foi realizar revisão sistemática de estudos que investigaram protocolos de desmame da ventilação não invasiva (VNI) em indivíduos adultos ou idosos hospitalizados. Por meio dessa revisão, baseada no protocolo Prisma, foram selecionados estudos de oito bases de dados publicados em português, inglês ou espanhol. Os desfechos primários desta revisão foram taxa de sucesso de desmame da VNI, duração da VNI e duração da permanência na unidade de terapia intensiva (UTI) e no hospital, e como desfecho secundário foram considerados os efeitos adversos associados aos protocolos de desmame da VNI. A qualidade metodológica dos ensaios clínicos foi avaliada por meio da escala PEDro, e a escala de Downs e Black foi utilizada para a avaliação dos estudos observacionais. Das 18.476 referências iniciais, quatro atenderam aos critérios de inclusão e foram incluídas nesta revisão. Dois dos quatro artigos eram ensaios clínicos randomizados e os outros dois eram estudos observacionais. Os estudos envolveram pacientes idosos com insuficiência respiratória, principalmente por exacerbação da doença pulmonar obstrutiva crônica (DPOC) e edema agudo de pulmão cardiogênico. Foram observadas elevadas taxas de sucesso de desmame em três dos quatro estudos, e um destes demonstrou a superioridade da implementação de um protocolo de desmame imediato na redução da duração da VNI e da permanência na UTI. No entanto, devido à heterogeneidade e à baixa qualidade metodológica dos estudos, não foi possível fazer recomendação sobre a implementação dos protocolos de desmame nessa população.

RESUMEN El objetivo de este trabajo ha sido realizar una revisión sistemática de estudios que investigaron protocolos de destete de la ventilación no invasiva (VNI) en individuos adultos o ancianos hospitalizados. A través de esta revisión, basada en el protocolo Prisma, se seleccionaron estudios de ocho bases de datos publicadas en portugués, inglés o español. Los resultados preliminares de esta revisión fueron la tasa de éxito de destete de la VNI, la duración de la VNI y la duración de la estancia en la unidad de cuidados intensivos (UCI) y en el hospital, y como resultado secundario se consideraron los efectos adversos asociados a los protocolos de destete de la VNI. La calidad metodológica de los ensayos clínicos ha sido evaluada a través de la escala PEDro, y la escala de Downs y Black ha sido utilizada para la evaluación de los estudios observacionales. De las 18.476 referencias iniciales, cuatro cumplieron los criterios de inclusión y se incluyeron en esta revisión. Dos de los cuatro artículos consistían en ensayos clínicos aleatorizados y los otros dos consistían en estudios observacionales. Los estudios incluyeron pacientes ancianos con insuficiencia respiratoria, principalmente por exacerbación de la enfermedad pulmonar obstructiva crónica (EPOC) y edema agudo de pulmón cardiogénico. Se observaron elevadas tasas de éxito de destete en tres de los cuatro estudios, y uno de éstos demostró la superioridad de la implementación de un protocolo de destete inmediato en la reducción de la duración de la VNI y de la permanencia en la UTI. Sin embargo, debido a la heterogeneidad y a la baja calidad metodológica de los estudios, no se pudo hacer recomendación sobre la implementación de los protocolos de destete en esa población.

ABSTRACT The aim of this study was to perform a systematic review of studies that investigated non-invasive ventilation (NIV) weaning protocols in adult or hospitalized elderly individuals. Through a systematic review based on the Prisma protocol, studies of eight databases published in Portuguese, English or Spanish were considered. The primary outcomes of this review were the success rate of NIV weaning, NIV duration and duration of intensive care unit (ICU) and hospital stay, and secondary endpoint were adverse events associated with protocols for NIV weaning. The methodological quality of clinical trials was assessed using the PEDro scale and for observational studies the Dows and Black scale. Four of the 18,476 initial references met the inclusion criteria and were included in this review. Two of the four articles were randomized clinical trials and two were observational studies. The studies assessed elderly patients with respiratory failure, mainly due to exacerbation of chronic obstructive pulmonary disease (COPD), and acute cardiogenic pulmonary edema. High weaning success rates were observed in three of the four studies, and one study demonstrated the superiority of implementing an immediate protocol for weaning to reduce NIV duration and ICU stay. However, because of the heterogeneity and poor methodological quality of the studies, it is not possible to make recommendations on the implementation of weaning protocols in this population.

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BACKGROUND: Neurally Adjusted Ventilatory Assist (NAVA) is a proportional ventilatory mode that uses the electrical activity of the diaphragm (EAdi) to offer ventilatory assistance in proportion to patient effort. NAVA has been increasingly used for critically ill patients, but it has not been evaluated during spontaneous breathing trials (SBT). We designed a pilot trial to assess the feasibility of using NAVA during SBTs, and to compare the breathing pattern and patient-ventilator asynchrony of NAVA with Pressure Support (PSV) during SBTs. METHODS: We conducted a crossover trial in the ICU of a university hospital in Brazil and included mechanically ventilated patients considered ready to undergo an SBT on the day of the study. Patients underwent two SBTs in randomized order: 30 min in PSV of 5 cmH2O or NAVA titrated to generate equivalent peak airway pressure (Paw), with a positive end-expiratory pressure of 5 cmH2O. The ICU team, blinded to ventilatory mode, evaluated whether patients passed each SBT. We captured flow, Paw and electrical activity of the diaphragm (EAdi) from the ventilator and used it to calculate respiratory rate (RR), tidal volume (VT), and EAdi. Detection of asynchrony events used waveform analysis and we calculated the asynchrony index as the number of asynchrony events divided by the number of neural cycles. RESULTS: We included 20 patients in the study. All patients passed the SBT in PSV, and three failed the SBT in NAVA. Five patients were reintubated and the extubation failure rate was 25% (95% CI 9-49%). Respiratory parameters were similar in the two modes: VT = 6.1 (5.5-6.5) mL/Kg in NAVA vs. 5.5 (4.8-6.1) mL/Kg in PSV (p = 0.076) and RR = 27 (17-30) rpm in NAVA vs. 26 (20-30) rpm in PSV, p = 0.55. NAVA reduced AI, with a median of 11.5% (4.2-19.7) compared to 24.3% (6.3-34.3) in PSV (p = 0.033). CONCLUSIONS: NAVA reduces patient-ventilator asynchrony index and generates a respiratory pattern similar to PSV during SBTs. Patients considered ready for mechanical ventilation liberation may be submitted to an SBT in NAVA using the same objective criteria used for SBTs in PSV. TRIAL REGISTRATION: ClinicalTrials.gov ( NCT01337271 ), registered April 12, 2011.

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INTRODUCTION: The application of expiratory positive airway pressure (EPAP) in patients with COPD during exercise may reduce dynamic hyperinflation, while, on the other hand, it can increase the resistive work of breathing. Therefore, we evaluated the effects of 2 intensities of EPAP during exercise on tolerance, dynamic hyperinflation, and dyspnea in subjects with moderate to very severe COPD. METHODS: We performed a cross-sectional, experimental, 4-visit study. In visit 1, subjects performed symptom-limited cycling incremental cardiopulmonary exercise test (CPET). In visits 2-4, at least 48 h apart, in a randomized order, subjects performed constant CPET without EPAP, EPAP with 5 cm H2O (EPAP5), or EPAP with 10 cm H2O (EPAP10). RESULTS: The study included 15 non-hypoxemic subjects ranging from moderate to very severe COPD (mean FEV1 = 35 ± 11% predicted). Increasing intensities of EPAP during constant CPET tended to cause progressive reduction in exercise tolerance (P = .11). Of note, 10 of 15 subjects demonstrated significantly shorter average exercise duration with EPAP10 compared to the test without EPAP (-151 ± 105 s, P = .03 or -41 ± 26%). Minute ventilation increment was constrained by EPAP, secondary to a limited increase in tidal volume (P = .01). Finally, dyspnea sensation and serial measurements of inspiratory capacity during exercise were similar when comparing the three interventions at isotime and at end-constant CPETs. CONCLUSIONS: The application of EPAP5 or EPAP10 during exercise tended to cause a progressive reduction in exercise tolerance in subjects with COPD without improvement in dyspnea or dynamic hyperinflation at equivalent exercise duration.

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